JPWO2019021450A1 - Air conditioner, air conditioning system, and control method of air conditioner - Google Patents

Abstract

The air conditioner (500) receives a converter (102) that generates a bus voltage applied to the coil (3), a connection switching unit (60) that switches a connection state of the coil (3), and an operation mode signal. A signal receiving unit (56) and a control device (50) for controlling the operation mode based on the operation mode signal are provided.

Description

  The present invention relates to an air conditioner.

  For motors used in air conditioners and the like, in order to improve the operation efficiency at the time of low speed rotation and high speed rotation, the connection state of the motor coil is Y connection (star connection) and delta connection (also called triangle connection or Δ connection). (For example, refer to Patent Document 1).

JP 2009-216324 A

  However, the conventional technology has a problem in that it cannot quickly respond to a sudden change in air conditioning load because the connection state of the coil of the motor is not properly controlled according to the operation mode of the air conditioner.

  An object of this invention is to control the connection state of a coil appropriately according to the operation mode of an air conditioner.

  An air conditioner according to the present invention is an air conditioner including an electric motor having a coil, wherein the converter generates a bus voltage applied to the coil, the connection state of the coil, the first connection state, and the A connection switching unit that switches between a second connection state that lowers the line voltage of the coil from the first connection state, and a signal reception that receives an operation mode signal for controlling the operation mode of the air conditioner And a control device that receives the operation mode signal from the signal reception unit and controls the operation mode based on the operation mode signal.

  ADVANTAGE OF THE INVENTION According to this invention, the connection state of a coil can be appropriately controlled according to the operation mode of an air conditioner.

1 is a cross-sectional view illustrating a configuration of an electric motor according to a first embodiment. FIG. 3 is a cross-sectional view illustrating a configuration of the rotary compressor according to the first embodiment. 1 is a block diagram illustrating a configuration of an air conditioner according to Embodiment 1. FIG. 2 is a conceptual diagram illustrating a basic configuration of a control system of the air conditioner according to Embodiment 1. FIG. It is a block diagram (A) which shows the control system of the air conditioner of Embodiment 1, and a block diagram (B) which shows the part which controls the electric motor of a compressor based on room temperature. FIG. 2 is a block diagram illustrating a configuration of the drive device according to the first embodiment. FIG. 2 is a block diagram illustrating a configuration of the drive device according to the first embodiment. FIG. 4 is a schematic diagram (A) and (B) illustrating a switching operation of a coil connection state according to the first embodiment. FIG. 3 is a schematic diagram illustrating a connection state of a coil according to the first embodiment. 3 is a flowchart showing a basic operation of the air conditioner of the first embodiment. 3 is a flowchart illustrating connection switching operation of the air conditioner according to the first embodiment. 3 is a flowchart illustrating connection switching operation of the air conditioner according to the first embodiment. It is the flowcharts (A) and (B) which show the other example of the connection switching operation | movement of the air conditioner of Embodiment 1. FIG. 3 is a timing chart illustrating an example of an operation of the air conditioner according to the first embodiment. In an electric motor, it is a graph which shows the relationship between the line voltage at the time of connecting a coil by Y connection, and rotation speed. In an electric motor, it is a graph which shows the relationship between the line voltage at the time of connecting a coil by Y connection and performing field-weakening control, and rotation speed. It is a graph which shows the relationship between the motor efficiency at the time of performing the field weakening control shown in FIG. 16, and rotation speed. It is a graph which shows the relationship between the motor torque at the time of performing the field weakening control shown in FIG. 16, and rotation speed. It is a graph which shows the relationship between a line voltage and a rotation speed in each of the case where the connection state of a coil is set to Y connection, and the case where it is set as delta connection. It is a graph which shows the relationship between the line voltage at the time of switching from Y connection to delta connection, and rotation speed. It is a graph which shows the relationship between an electric motor efficiency and rotation speed in each of the case where the connection state of a coil is set to Y connection, and the case where it is set as a delta connection. Motor efficiency when the coil connection state is Y connection, the number of turns is adjusted so that the line voltage reaches the inverter maximum output voltage at a slightly lower rotation speed than the heating intermediate condition, and the Y connection is switched to the delta connection It is a graph which shows the relationship between and rotation speed. It is a graph which shows the relationship between an electric motor torque and the rotation speed in each of the case where the connection state of a coil is set to Y connection, and the case where it is set as delta connection. Motor torque when the coil connection state is Y connection, the number of turns is adjusted so that the line voltage reaches the inverter maximum output voltage at a slightly lower rotation speed than the heating intermediate condition, and the Y connection is switched to the delta connection It is a graph which shows the relationship between rotation speed. It is a graph which shows the relationship between the line voltage at the time of switching a bus-line voltage with a converter, and rotation speed. In Embodiment 1, it is a graph which shows the relationship between the line voltage at the time of switching the connection state of a coil, and switching of the bus-line voltage of a converter, and rotation speed. It is a graph which shows the relationship between an electric motor efficiency and rotation speed in each of the case where the connection state of a coil is set to Y connection, and the case where it is set as a delta connection. In Embodiment 1, it is a graph which shows the relationship between the motor efficiency at the time of switching the connection state of a coil, and switching the bus-line voltage of a converter, and rotation speed. It is a graph which shows the relationship between an electric motor torque and the rotation speed in each of the case where the connection state of a coil is set to Y connection, and the case where it is set as delta connection. In Embodiment 1, it is a graph which shows the relationship between the motor efficiency at the time of switching the connection state of a coil, and switching the bus-line voltage of a converter, and rotation speed. It is the graphs (A) and (B) which show the relationship between the motor efficiency in the 1st modification of Embodiment 1, and rotation speed. 10 is a graph showing the relationship between line voltage and rotation speed in the second modification of the first embodiment. FIG. 10 is a schematic diagram (A) and (B) for explaining the coil connection state switching operation of the third modification of the first embodiment. FIG. 10 is a schematic diagram (A) and (B) for explaining another example of the coil connection state switching operation of the third modification of the first embodiment. 10 is a flowchart showing a connection switching operation in a fourth modification of the first embodiment. 10 is a flowchart showing a connection switching operation in a fifth modification of the first embodiment. It is a block diagram which shows the structure of the air conditioning system which has the air conditioner of Embodiment 2. FIG. It is a block diagram which shows the structure of the air conditioner of Embodiment 2. 6 is a block diagram illustrating a control system of an air conditioner according to Embodiment 2. FIG. FIG. 6 is a block diagram illustrating a control system of a drive device according to a second embodiment. It is a figure which shows the structure of a communication apparatus. It is a flowchart which shows an example of operation | movement of a control apparatus. It is a flowchart which shows an example of other operation | movement of a control apparatus. It is a flowchart which shows an example of other operation | movement of a control apparatus.

Embodiment 1 FIG.
<Configuration of motor>
Embodiment 1 of the present invention will be described. FIG. 1 is a cross-sectional view showing a configuration of an electric motor 1 according to Embodiment 1 of the present invention. The electric motor 1 is a permanent magnet embedded electric motor, and is used, for example, in a rotary compressor. The electric motor 1 includes a stator 10 and a rotor 20 that is rotatably provided inside the stator 10. For example, an air gap of 0.3 to 1 mm is formed between the stator 10 and the rotor 20. FIG. 1 is a cross-sectional view of a plane orthogonal to the rotation axis of the rotor 20.

  Hereinafter, the axial direction of the rotor 20 (direction of the rotation axis) is simply referred to as “axial direction”. The direction along the outer circumference (circumference) of the stator 10 and the rotor 20 is simply referred to as “circumferential direction”. The radial direction of the stator 10 and the rotor 20 is simply referred to as “radial direction”.

  The stator 10 includes a stator core 11 and a coil 3 wound around the stator core 11. The stator core 11 is formed by laminating a plurality of electromagnetic steel plates having a thickness of 0.1 to 0.7 mm (here 0.35 mm) in the direction of the rotation axis and fastening them by caulking.

  The stator core 11 has an annular yoke portion 13 and a plurality of (here, nine) tooth portions 12 projecting radially inward from the yoke portion 13. A slot is formed between adjacent teeth portions 12. Each tooth portion 12 has a tooth tip portion having a wide width (dimension in the circumferential direction of the stator core 11) at the radially inner tip.

  A coil 3, which is a stator winding, is wound around each tooth portion 12 via an insulator (insulator) 14. For example, the coil 3 is obtained by winding a magnet wire having a wire diameter (diameter) of 0.8 mm around each tooth portion 12 by 110 winding (110 turns) by concentrated winding. The number of turns and the wire diameter of the coil 3 are determined in accordance with characteristics (rotation speed, torque, etc.) required for the electric motor 1, supply voltage, or cross-sectional area of the slot.

  The coil 3 is composed of U-phase, V-phase, and W-phase three-phase coils (referred to as coils 3U, 3V, and 3W). Both terminals of the coil 3 of each phase are open. That is, the coil 3 has a total of six terminals. As will be described later, the connection state of the coil 3 is configured to be switchable between a Y connection and a delta connection. The insulator 14 is made of, for example, a film made of PET (polyethylene terephthalate) and has a thickness of 0.1 to 0.2 mm.

  The stator core 11 has a configuration in which a plurality of (here, nine) blocks are connected via a thin portion. In a state where the stator core 11 is developed in a band shape, a magnet wire is wound around each tooth portion 12, and then the stator core 11 is bent in an annular shape and both ends are welded.

  As described above, it is effective to increase the number of turns of the coil 3 in the slot by forming the insulator 14 with a thin film and making the stator core 11 in a divided structure so that winding is easy. The stator core 11 is not limited to one having a configuration in which a plurality of blocks (divided cores) are connected as described above.

  The rotor 20 includes a rotor core 21 and a permanent magnet 25 attached to the rotor core 21. The rotor core 21 is formed by laminating a plurality of electromagnetic steel plates having a thickness of 0.1 to 0.7 mm (here 0.35 mm) in the direction of the rotation axis and fastening them by caulking.

  The rotor core 21 has a cylindrical shape, and a shaft hole 27 (center hole) is formed at the center in the radial direction. In the shaft hole 27, a shaft (for example, the shaft 90 of the rotary compressor 8) serving as the rotation axis of the rotor 20 is fixed by shrink fitting or press fitting.

  A plurality (six in this case) of magnet insertion holes 22 into which the permanent magnets 25 are inserted are formed along the outer peripheral surface of the rotor core 21. The magnet insertion hole 22 is a gap, and one magnet insertion hole 22 corresponds to one magnetic pole. Here, since six magnet insertion holes 22 are provided, the rotor 20 as a whole has six poles.

  Here, the magnet insertion hole 22 has a V shape in which a central portion in the circumferential direction protrudes radially inward. The magnet insertion hole 22 is not limited to the V shape, and may be, for example, a straight shape.

  Two permanent magnets 25 are arranged in one magnet insertion hole 22. That is, two permanent magnets 25 are arranged for one magnetic pole. Here, since the rotor 20 has six poles as described above, a total of twelve permanent magnets 25 are arranged.

  The permanent magnet 25 is a flat plate-like member that is long in the axial direction of the rotor core 21, has a width in the circumferential direction of the rotor core 21, and has a thickness in the radial direction. The permanent magnet 25 is composed of, for example, a rare earth magnet mainly composed of neodymium (Nd), iron (Fe), and boron (B).

  The permanent magnet 25 is magnetized in the thickness direction. The two permanent magnets 25 arranged in one magnet insertion hole 22 are magnetized such that the same magnetic poles face the same radial direction.

  Flux barriers 26 are formed on both sides of the magnet insertion hole 22 in the circumferential direction. The flux barrier 26 is a space formed continuously from the magnet insertion hole 22. The flux barrier 26 is for suppressing leakage magnetic flux between adjacent magnetic poles (that is, magnetic flux flowing through the poles).

  In the rotor core 21, a first magnet holding portion 23, which is a protrusion, is formed at the center portion in the circumferential direction of each magnet insertion hole 22. Moreover, in the rotor core 21, the 2nd magnet holding | maintenance part 24 which is a protrusion is formed in the both ends of the circumferential direction of the magnet insertion hole 22, respectively. The first magnet holding part 23 and the second magnet holding part 24 position and hold the permanent magnet 25 in each magnet insertion hole 22.

  As described above, the number of slots of the stator 10 (that is, the number of teeth portions 12) is 9, and the number of poles of the rotor 20 is 6. That is, in the electric motor 1, the ratio between the number of poles of the rotor 20 and the number of slots of the stator 10 is 2: 3.

  In the electric motor 1, the connection state of the coil 3 is switched between the Y connection and the delta connection. However, when the delta connection is used, there is a possibility that the circulating current flows and the performance of the electric motor 1 is deteriorated. The circulating current is caused by the third harmonic generated in the induced voltage in the winding of each phase. In the case of concentrated winding in which the ratio of the number of poles to the number of slots is 2: 3, the third harmonic is not generated in the induced voltage unless there is an influence of magnetic saturation or the like, and therefore performance degradation due to circulating current occurs. Not known.

<Configuration of rotary compressor>
Next, the rotary compressor 8 using the electric motor 1 will be described. FIG. 2 is a cross-sectional view showing the configuration of the rotary compressor 8. The rotary compressor 8 includes a shell 80, a compression mechanism 9 disposed in the shell 80, and an electric motor 1 that drives the compression mechanism 9. The rotary compressor 8 further includes a shaft 90 (crankshaft) that couples the electric motor 1 and the compression mechanism 9 so that power can be transmitted. The shaft 90 is fitted into the shaft hole 27 (FIG. 1) of the rotor 20 of the electric motor 1.

  The shell 80 is a sealed container formed of, for example, a steel plate and covers the electric motor 1 and the compression mechanism 9. The shell 80 has an upper shell 80a and a lower shell 80b. The upper shell 80a has a glass terminal 81 as a terminal for supplying electric power to the electric motor 1 from the outside of the rotary compressor 8, and a discharge pipe for discharging the refrigerant compressed in the rotary compressor 8 to the outside. 85 is attached. Here, a total of six lead wires corresponding to two of each of the U phase, the V phase, and the W phase of the coil 3 of the electric motor 1 (FIG. 1) are drawn out from the glass terminal 81. The lower shell 80b houses the electric motor 1 and the compression mechanism 9.

  The compression mechanism 9 has an annular first cylinder 91 and second cylinder 92 along the shaft 90. The first cylinder 91 and the second cylinder 92 are fixed to the inner peripheral portion of the shell 80 (lower shell 80b). An annular first piston 93 is disposed on the inner peripheral side of the first cylinder 91, and an annular second piston 94 is disposed on the inner peripheral side of the second cylinder 92. The first piston 93 and the second piston 94 are rotary pistons that rotate with the shaft 90.

  A partition plate 97 is provided between the first cylinder 91 and the second cylinder 92. The partition plate 97 is a disk-shaped member having a through hole in the center. The cylinder chambers of the first cylinder 91 and the second cylinder 92 are provided with vanes (not shown) that divide the cylinder chamber into a suction side and a compression side. The first cylinder 91, the second cylinder 92, and the partition plate 97 are integrally fixed by bolts 98.

  An upper frame 95 is arranged on the upper side of the first cylinder 91 so as to close the upper side of the cylinder chamber of the first cylinder 91. A lower frame 96 is disposed below the second cylinder 92 so as to close the lower side of the cylinder chamber of the second cylinder 92. The upper frame 95 and the lower frame 96 support the shaft 90 in a rotatable manner.

  Refrigerating machine oil (not shown) that lubricates the sliding portions of the compression mechanism 9 is stored at the bottom of the lower shell 80 b of the shell 80. The refrigerating machine oil ascends in the hole 90 a formed in the axial direction inside the shaft 90, and is supplied to each sliding portion from oil supply holes 90 b formed in a plurality of locations of the shaft 90.

  The stator 10 of the electric motor 1 is attached to the inside of the shell 80 by shrink fitting. Electric power is supplied to the coil 3 of the stator 10 from a glass terminal 81 attached to the upper shell 80a. A shaft 90 is fixed to the shaft hole 27 (FIG. 1) of the rotor 20.

  An accumulator 87 for storing the refrigerant gas is attached to the shell 80. The accumulator 87 is held by, for example, a holding portion 80c provided outside the lower shell 80b. A pair of suction pipes 88 and 89 are attached to the shell 80, and refrigerant gas is supplied from the accumulator 87 to the first cylinder 91 and the second cylinder 92 via the suction pipes 88 and 89.

  For example, R410A, R407C, or R22 may be used as the refrigerant. However, from the viewpoint of preventing global warming, it is desirable to use a low GWP (global warming potential) refrigerant. For example, the following refrigerants can be used as the low GWP refrigerant.

(1) First, a halogenated hydrocarbon having a carbon double bond in its composition, for example, HFO (Hydro-Fluoro-Orefin) -1234yf (CF3CF = CH2) can be used. The GWP of HFO-1234yf is 4.
(2) A hydrocarbon having a carbon double bond in the composition, for example, R1270 (propylene) may be used. R1270 has a GWP of 3, which is lower than HFO-1234yf, but flammability is higher than HFO-1234yf.
(3) A mixture containing at least one of a halogenated hydrocarbon having a carbon double bond in the composition or a hydrocarbon having a carbon double bond in the composition, for example, a mixture of HFO-1234yf and R32 It may be used. Since HFO-1234yf described above is a low-pressure refrigerant, the pressure loss tends to increase, and there is a possibility that the performance of the refrigeration cycle (especially the evaporator) will deteriorate. Therefore, it is practically desirable to use a mixture with R32 or R41, which is a high-pressure refrigerant, rather than HFO-1234yf.

  The basic operation of the rotary compressor 8 is as follows. The refrigerant gas supplied from the accumulator 87 is supplied to the cylinder chambers of the first cylinder 91 and the second cylinder 92 through the suction pipes 88 and 89. When the electric motor 1 is driven and the rotor 20 rotates, the shaft 90 rotates together with the rotor 20. Then, the first piston 93 and the second piston 94 fitted to the shaft 90 rotate eccentrically in each cylinder chamber, and compress the refrigerant in each cylinder chamber. The compressed refrigerant rises in the shell 80 through a hole (not shown) provided in the rotor 20 of the electric motor 1 and is discharged from the discharge pipe 85 to the outside.

<Configuration of air conditioner>
Next, the air conditioner 5 including the drive device of Embodiment 1 will be described. FIG. 3 is a block diagram showing the configuration of the air conditioner 5. The air conditioner 5 includes an indoor unit 5A installed indoors (air-conditioning target space) and an outdoor unit 5B installed outdoors. The indoor unit 5A and the outdoor unit 5B are connected by connection pipes 40a and 40b through which the refrigerant flows. The liquid refrigerant that has passed through the condenser flows through the connection pipe 40a. The gas refrigerant that has passed through the evaporator flows through the connection pipe 40b.

  The outdoor unit 5B includes a compressor 41 that compresses and discharges the refrigerant, a four-way valve (refrigerant flow switching valve) 42 that switches the flow direction of the refrigerant, and an outdoor heat exchanger 43 that performs heat exchange between the outside air and the refrigerant. And an expansion valve (decompression device) 44 for depressurizing the high-pressure refrigerant to a low pressure. The compressor 41 is composed of the rotary compressor 8 (FIG. 2) described above. In the indoor unit 5A, an indoor heat exchanger 45 that performs heat exchange between the indoor air and the refrigerant is disposed.

  The compressor 41, the four-way valve 42, the outdoor heat exchanger 43, the expansion valve 44, and the indoor heat exchanger 45 are connected by the pipe 40 including the connection pipes 40a and 40b described above, and constitute a refrigerant circuit. These components constitute a compression refrigeration cycle (compression heat pump cycle) in which the refrigerant is circulated by the compressor 41.

  In order to control the operation of the air conditioner 5, an indoor control device 50a is disposed in the indoor unit 5A, and an outdoor control device 50b is disposed in the outdoor unit 5B. Each of the indoor control device 50a and the outdoor control device 50b has a control board on which various circuits for controlling the air conditioner 5 are formed. The indoor control device 50a and the outdoor control device 50b are connected to each other by a communication cable 50c. The connection cable 50c is bundled together with the connection pipes 40a and 40b described above.

  In the outdoor unit 5 </ b> B, an outdoor blower fan 46 that is a blower is disposed so as to face the outdoor heat exchanger 43. The outdoor blower fan 46 generates an air flow passing through the outdoor heat exchanger 43 by rotation. The outdoor blower fan 46 is composed of, for example, a propeller fan.

  The four-way valve 42 is controlled by the outdoor control device 50b and switches the direction in which the refrigerant flows. When the four-way valve 42 is in the position indicated by the solid line in FIG. 3, the gas refrigerant discharged from the compressor 41 is sent to the outdoor heat exchanger 43 (condenser). On the other hand, when the four-way valve 42 is at the position indicated by the broken line in FIG. 3, the gas refrigerant flowing from the outdoor heat exchanger 43 (evaporator) is sent to the compressor 41. The expansion valve 44 is controlled by the outdoor control device 50b, and depressurizes the high-pressure refrigerant to a low pressure by changing the opening degree.

  In the indoor unit 5A, an indoor blower fan 47, which is a blower, is disposed so as to face the indoor heat exchanger 45. The indoor blower fan 47 generates an air flow that passes through the indoor heat exchanger 45 by rotation. The indoor blower fan 47 is constituted by, for example, a cross flow fan.

  The indoor unit 5A is provided with an indoor temperature sensor 54 as a temperature sensor that measures the indoor temperature Ta, which is the air temperature of the room (the air conditioning target space), and sends the measured temperature information (information signal) to the indoor control device 50a. ing. The indoor temperature sensor 54 may be a temperature sensor used in a general air conditioner, or a radiation temperature sensor that detects a surface temperature of an indoor wall or floor.

  The indoor unit 5A is also provided with a signal receiving unit 56 that receives an instruction signal (driving instruction signal) transmitted from a remote controller 55 (remote operation device) operated by the user. The remote controller 55 is used by the user to instruct the air conditioner 5 for operation input (operation start and stop) or operation details (set temperature, wind speed, etc.).

  The compressor 41 is configured to be able to change the operating rotational speed in the range of 20 to 130 rps during normal operation. As the rotational speed of the compressor 41 increases, the amount of refrigerant circulating in the refrigerant circuit increases. The number of revolutions of the compressor 41 depends on the temperature difference ΔT between the current room temperature Ta obtained by the room temperature sensor 54 and the set temperature Ts set by the user with the remote controller 55 (more specifically, the control device 50). The outdoor control device 50b) controls. The larger the temperature difference ΔT, the higher the rotation of the compressor 41 and increases the amount of refrigerant circulation.

  The rotation of the indoor fan 47 is controlled by the indoor control device 50a. The number of rotations of the indoor fan 47 can be switched between a plurality of stages. Here, for example, the number of rotations can be switched in three stages of strong wind, medium wind, and weak wind. When the wind speed setting is set to the automatic mode with the remote controller 55, the rotational speed of the indoor fan 47 is switched according to the temperature difference ΔT between the measured indoor temperature Ta and the set temperature Ts.

  The rotation of the outdoor fan 46 is controlled by the outdoor control device 50b. The number of rotations of the outdoor fan 46 can be switched between a plurality of stages. Here, the rotational speed of the outdoor blower fan 46 is switched according to the temperature difference ΔT between the measured indoor temperature Ta and the set temperature Ts.

  The indoor unit 5 </ b> A also includes a left / right wind direction plate 48 and an up / down wind direction plate 49. The left and right wind direction plates 48 and the up and down wind direction plates 49 change the blowing direction when the conditioned air heat-exchanged by the indoor heat exchanger 45 is blown into the room by the indoor fan 47. The left and right wind direction plates 48 change the blowing direction to the left and right, and the upper and lower wind direction plates 49 change the blowing direction to the up and down directions. The indoor control device 50 a controls the angles of the left and right wind direction plates 48 and the upper and lower wind direction plates 49, that is, the wind direction of the blown airflow, based on the settings of the remote controller 55.

  The basic operation of the air conditioner 5 is as follows. During the cooling operation, the four-way valve 42 is switched to the position indicated by the solid line, and the high-temperature and high-pressure gas refrigerant discharged from the compressor 41 flows into the outdoor heat exchanger 43. In this case, the outdoor heat exchanger 43 operates as a condenser. When the air passes through the outdoor heat exchanger 43 due to the rotation of the outdoor blower fan 46, the heat of heat condenses the refrigerant. The refrigerant condenses into a high-pressure and low-temperature liquid refrigerant, and adiabatically expands at the expansion valve 44 to become a low-pressure and low-temperature two-phase refrigerant.

  The refrigerant that has passed through the expansion valve 44 flows into the indoor heat exchanger 45 of the indoor unit 5A. The indoor heat exchanger 45 operates as an evaporator. When the air passes through the indoor heat exchanger 45 due to the rotation of the indoor blower fan 47, the refrigerant takes heat of evaporation by heat exchange, and the air thus cooled is supplied indoors. The refrigerant evaporates into a low-temperature and low-pressure gas refrigerant, and is compressed again by the compressor 41 into a high-temperature and high-pressure refrigerant.

  During the heating operation, the four-way valve 42 is switched to the position indicated by the dotted line, and the high-temperature and high-pressure gas refrigerant discharged from the compressor 41 flows into the indoor heat exchanger 45. In this case, the indoor heat exchanger 45 operates as a condenser. When the air passes through the indoor heat exchanger 45 due to the rotation of the indoor fan 47, the heat is deprived of the condensation heat from the refrigerant, and the heated air is supplied indoors. The refrigerant condenses into a high-pressure and low-temperature liquid refrigerant, and adiabatically expands at the expansion valve 44 to become a low-pressure and low-temperature two-phase refrigerant.

  The refrigerant that has passed through the expansion valve 44 flows into the outdoor heat exchanger 43 of the outdoor unit 5B. The outdoor heat exchanger 43 operates as an evaporator. When the air passes through the outdoor heat exchanger 43 due to the rotation of the outdoor blower fan 46, the heat is deprived of the evaporation heat by the heat exchange. The refrigerant evaporates into a low-temperature and low-pressure gas refrigerant, and is compressed again by the compressor 41 into a high-temperature and high-pressure refrigerant.

  FIG. 4 is a conceptual diagram showing the basic configuration of the control system of the air conditioner 5. The indoor control device 50a and the outdoor control device 50b described above exchange information with each other via the communication cable 50c to control the air conditioner 5. Here, the indoor control device 50a and the outdoor control device 50b are collectively referred to as a control device 50.

  FIG. 5A is a block diagram showing a control system of the air conditioner 5. The control device 50 is configured by a microcomputer, for example. The control device 50 incorporates an input circuit 51, an arithmetic circuit 52, and an output circuit 53.

  An instruction signal received by the signal receiving unit 56 from the remote controller 55 is input to the input circuit 51. The instruction signal includes, for example, a signal for setting an operation input, an operation mode, a set temperature, an air volume or a wind direction. The input circuit 51 also receives temperature information indicating the room temperature detected by the room temperature sensor 54. The input circuit 51 outputs the input information to the arithmetic circuit 52.

  The arithmetic circuit 52 includes a CPU (Central Processing Unit) 57 and a memory 58. The CPU 57 performs calculation processing and determination processing. The memory 58 stores various set values and programs used for controlling the air conditioner 5. The arithmetic circuit 52 performs calculation and determination based on the information input from the input circuit 51 and outputs the result to the output circuit 53.

  The output circuit 53 is based on information input from the arithmetic circuit 52, and includes a compressor 41, a connection switching unit 60 (described later), a converter 102, an inverter 103, a compressor 41, a four-way valve 42, an expansion valve 44, and an outdoor fan. 46, a control signal is output to the indoor fan 47, the left / right wind direction plate 48 and the up / down wind direction plate 49.

  As described above, the indoor control device 50a and the outdoor control device 50b (FIG. 4) exchange information with each other via the communication cable 50c and control various devices of the indoor unit 5A and the outdoor unit 5B. Here, the indoor control device 50a and the outdoor control device 50b are collectively expressed as a control device 50. Actually, each of the indoor control device 50a and the outdoor control device 50b is constituted by a microcomputer. Note that a control device may be mounted on only one of the indoor unit 5A and the outdoor unit 5B, and various devices of the indoor unit 5A and the outdoor unit 5B may be controlled.

  FIG. 5B is a block diagram illustrating a portion of the control device 50 that controls the electric motor 1 of the compressor 41 based on the indoor temperature Ta. The arithmetic circuit 52 of the control device 50 includes a reception content analysis unit 52a, an indoor temperature acquisition unit 52b, a temperature difference calculation unit 52c, and a compressor control unit 52d. These are included in the CPU 57 of the arithmetic circuit 52, for example.

  The reception content analysis unit 52 a analyzes the instruction signal input from the remote controller 55 via the signal reception unit 56 and the input circuit 51. Based on the analysis result, the reception content analysis unit 52a outputs, for example, the operation mode and the set temperature Ts to the temperature difference calculation unit 52c. The room temperature acquisition unit 52b acquires the room temperature Ta input from the room temperature sensor 54 via the input circuit 51, and outputs it to the temperature difference calculation unit 52c.

  The temperature difference calculation unit 52c calculates a temperature difference ΔT between the room temperature Ta input from the room temperature acquisition unit 52b and the set temperature Ts input from the received content analysis unit 52a. When the operation mode input from the received content analysis unit 52a is the heating operation, the temperature difference ΔT = Ts−Ta is calculated. When the operation mode is the cooling operation, the temperature difference ΔT = Ta−Ts is calculated. The temperature difference calculation unit 52c outputs the calculated temperature difference ΔT to the compressor control unit 52d.

  The compressor control unit 52d controls the drive device 100 based on the temperature difference ΔT input from the temperature difference calculation unit 52c, thereby controlling the rotational speed of the electric motor 1 (that is, the rotational speed of the compressor 41).

<Configuration of drive device>
Next, the drive device 100 that drives the electric motor 1 will be described. FIG. 6 is a block diagram illustrating a configuration of the driving device 100. The drive device 100 includes a converter 102 that rectifies the output of the power source 101, an inverter 103 that outputs an AC voltage to the coil 3 of the electric motor 1, a connection switching unit 60 that switches a connection state of the coil 3, and a control device 50. Configured. Power is supplied to the converter 102 from a power source 101 which is an alternating current (AC) power source.

  The power source 101 is an AC power source of 200 V (effective voltage), for example. The converter 102 is a rectifier circuit and outputs a direct current (DC) voltage of, for example, 280V. The voltage output from converter 102 is referred to as bus voltage. The inverter 103 is supplied with a bus voltage from the converter 102 and outputs a line voltage (also referred to as a motor voltage) to the coil 3 of the motor 1. Wirings 104, 105, 106 connected to the coils 3U, 3V, 3W, respectively, are connected to the inverter 103.

  The coil 3U has terminals 31U and 32U. The coil 3V has terminals 31V and 32V. The coil 3W has terminals 31W and 32W. The wiring 104 is connected to the terminal 31U of the coil 3U. The wiring 105 is connected to the terminal 31V of the coil 3V. The wiring 106 is connected to the terminal 31W of the coil 3W.

  The connection switching unit 60 includes switches 61, 62, and 63. The switch 61 connects the terminal 32U of the coil 3U to either the wiring 105 or the neutral point 33. The switch 62 connects the terminal 32V of the coil 3V to either the wiring 106 or the neutral point 33. The switch 63 connects the terminal 32 </ b> W of the coil 3 </ b> V to either the wiring 104 or the neutral point 33. Here, the switches 61, 62, 63 of the connection switching unit 60 are constituted by relay contacts. However, you may comprise with a semiconductor switch.

  The control device 50 controls the converter 102, the inverter 103, and the connection switching unit 60. The configuration of the control device 50 is as described with reference to FIG. The controller 50 receives the operation instruction signal from the remote controller 55 received by the signal receiver 56 and the room temperature detected by the room temperature sensor 54. Based on the input information, control device 50 outputs a voltage switching signal to converter 102, outputs an inverter drive signal to inverter 103, and outputs a connection switching signal to connection switching unit 60.

  In the state shown in FIG. 6, the switch 61 connects the terminal 32U of the coil 3U to the neutral point 33, the switch 62 connects the terminal 32V of the coil 3V to the neutral point 33, and the switch 63 Connects the terminal 32W of the coil 3W to the neutral point 33. That is, the terminals 31U, 31V, 31W of the coils 3U, 3V, 3W are connected to the inverter 103, and the terminals 32U, 32V, 32W are connected to the neutral point 33.

  FIG. 7 is a block diagram illustrating a state in which the switches 61, 62, and 63 of the connection switching unit 60 are switched in the driving device 100. In the state shown in FIG. 7, the switch 61 connects the terminal 32U of the coil 3U to the wiring 105, the switch 62 connects the terminal 32V of the coil 3V to the wiring 106, and the switch 63 is connected to the coil 3W. Terminal 32 </ b> W is connected to the wiring 104.

  FIG. 8A is a schematic diagram illustrating a connection state of the coils 3U, 3V, and 3W when the switches 61, 62, and 63 are in the state illustrated in FIG. Coils 3U, 3V, and 3W are connected to neutral point 33 at terminals 32U, 32V, and 32W, respectively. For this reason, the connection state of the coils 3U, 3V, and 3W is the Y connection (star connection).

  FIG. 8B is a schematic diagram illustrating a connection state of the coils 3U, 3V, and 3W when the switches 61, 62, and 63 are in the state illustrated in FIG. The terminal 32U of the coil 3U is connected to the terminal 31V of the coil 3V via the wiring 105 (FIG. 7). The terminal 32V of the coil 3V is connected to the terminal 31W of the coil 3W via the wiring 106 (FIG. 7). The terminal 32W of the coil 3W is connected to the terminal 31U of the coil 3U via the wiring 104 (FIG. 7). Therefore, the connection state of the coils 3U, 3V, 3W is a delta connection (triangular connection).

  As described above, the connection switching unit 60 switches the switches 61, 62, and 63 to change the connection state of the coils 3U, 3V, and 3W of the electric motor 1 from the Y connection (first connection state) and the delta connection (second connection). (Connection state) can be switched.

  FIG. 9 is a schematic diagram showing the coil portions of the coils 3U, 3V, and 3W. As described above, the electric motor 1 has nine tooth portions 12 (FIG. 1), and the coils 3U, 3V, and 3W are wound around the three tooth portions 12, respectively. That is, the coil 3U is obtained by connecting U-phase coil portions Ua, Ub, Uc wound around three teeth portions 12 in series. Similarly, the coil 3V is formed by connecting V-phase coil portions Va, Vb, and Vc wound around three teeth portions 12 in series. The coil 3W is formed by connecting W-phase coil portions Wa, Wb, Wc wound around three tooth portions 12 in series.

<Operation of air conditioner>
10 to 12 are flowcharts showing the basic operation of the air conditioner 5. The control device 50 of the air conditioner 5 starts operation by receiving the activation signal from the remote controller 55 by the signal receiving unit 56 (step S101). Here, the CPU 57 of the control device 50 is activated. As will be described later, since the air conditioner 5 has been completed by switching the connection state of the coil 3 to the delta connection at the end of the previous time, the connection state of the coil 3 becomes the delta connection at the start of operation (at the time of activation). ing.

  Next, the control apparatus 50 performs the starting process of the air conditioner 5 (step S102). Specifically, for example, the fan motors of the indoor fan 47 and the outdoor fan 46 are driven.

  Next, control device 50 outputs a voltage switching signal to converter 102, and boosts the bus voltage of converter 102 to a bus voltage (eg, 390 V) corresponding to the delta connection (step S103). The bus voltage of the converter 102 is the maximum voltage applied from the inverter 103 to the electric motor 1.

  Next, the control apparatus 50 starts the electric motor 1 (step S104). Thereby, as for the electric motor 1, the connection state of the coil 3 is started by the delta connection. Further, the control device 50 controls the output voltage of the inverter 103 to control the rotation speed of the electric motor 1.

  Specifically, control device 50 increases the rotational speed of electric motor 1 stepwise at a predetermined speed in accordance with temperature difference ΔT. The allowable maximum number of rotations of the rotation speed of the electric motor 1 is, for example, 130 rps. Thereby, the refrigerant | coolant circulation amount by the compressor 41 is increased, the cooling capability is improved in the cooling operation, and the heating capability is increased in the heating operation.

  Further, when the room temperature Ta approaches the set temperature Ts due to the air conditioning effect and the temperature difference ΔT shows a decreasing tendency, the control device 50 decreases the rotation speed of the electric motor 1 according to the temperature difference ΔT. When the temperature difference ΔT decreases to a predetermined near-zero temperature (however, greater than 0), the control device 50 operates the electric motor 1 at an allowable minimum rotational speed (for example, 20 rps).

  When the room temperature Ta reaches the set temperature Ts (that is, when the temperature difference ΔT is 0 or less), the control device 50 stops the rotation of the electric motor 1 to prevent overcooling (or overheating). To do. As a result, the compressor 41 is stopped. When the temperature difference ΔT becomes larger than 0 again, the control device 50 restarts the rotation of the electric motor 1. Note that the control device 50 regulates the resumption of rotation of the electric motor 1 in a short time so as not to repeat the rotation and stop of the electric motor 1 in a short time.

  Moreover, when the rotation speed of the electric motor 1 reaches a preset rotation speed, the inverter 103 starts field weakening control. The field weakening control will be described later with reference to FIGS.

  The control device 50 determines whether or not an operation stop signal (operation stop signal for the air conditioner 5) is received from the remote controller 55 via the signal receiving unit 56 (step S105). If the operation stop signal has not been received, the process proceeds to step S106. On the other hand, when the operation stop signal is received, the control device 50 proceeds to step S109.

  The control device 50 acquires a temperature difference ΔT between the room temperature Ta detected by the room temperature sensor 54 and the set temperature Ts set by the remote controller 55 (step S106), and based on this temperature difference ΔT, the delta of the coil 3 is obtained. It is determined whether or not switching from the connection to the Y connection is necessary. That is, it is determined whether the connection state of the coil 3 is a delta connection and the absolute value of the temperature difference ΔT is equal to or less than the threshold value ΔTr (step S107). The threshold value ΔTr is a temperature difference corresponding to an air conditioning load that is small enough to be switched to Y connection (also simply referred to as “load”).

  As described above, ΔT is represented by ΔT = Ts−Ta when the operation mode is the heating operation, and ΔT = Ta−Ts when the operation mode is the cooling operation. It is determined whether or not it is necessary to switch to Y connection by comparing ΔTr.

  As a result of the comparison in step S107, if the connection state of the coil 3 is delta connection and the absolute value of the temperature difference ΔT is equal to or less than the threshold value ΔTr, the process proceeds to step S121 (FIG. 11).

  As shown in FIG. 11, in step S <b> 121, control device 50 outputs a stop signal to inverter 103 to stop rotation of electric motor 1. Thereafter, the control device 50 outputs a connection switching signal to the connection switching unit 60, and switches the connection state of the coil 3 from the delta connection to the Y connection (step S122). Subsequently, control device 50 outputs a voltage switching signal to converter 102, reduces the bus voltage of converter 102 to a voltage (280 V) corresponding to the Y connection (step S123), and restarts rotation of electric motor 1 (step S123). S124). Then, it returns to step S105 (FIG. 10) mentioned above.

  As a result of the comparison in step S107, when the connection state of the coil 3 is not delta connection (Y connection), or when the absolute value of the temperature difference ΔT is larger than the threshold value ΔTr (that is, there is no need to switch to Y connection). In the case), the process proceeds to step S108.

  In step S108, it is determined whether or not switching from the Y connection to the delta connection is necessary. That is, it is determined whether or not the connection state of the coil 3 is the Y connection and the absolute value of the temperature difference ΔT is larger than the threshold value ΔTr.

  As a result of the comparison in step S108, if the connection state of the coil 3 is Y-connection and the absolute value of the temperature difference ΔT is larger than the threshold value ΔTr, the process proceeds to step S131 (FIG. 12).

  As shown in FIG. 12, in step S131, the control device 50 stops the rotation of the electric motor 1. Thereafter, the control device 50 outputs a connection switching signal to the connection switching unit 60, and switches the connection state of the coil 3 from the Y connection to the delta connection (step S132). Subsequently, control device 50 outputs a voltage switching signal to converter 102, boosts the bus voltage of converter 102 to a voltage (390 V) corresponding to the delta connection (step S133), and restarts rotation of electric motor 1 (step S133). S134).

  In the case of the delta connection, the electric motor 1 can be driven to a higher rotational speed than the Y connection, so that a larger load can be handled. Therefore, the temperature difference ΔT between the room temperature and the set temperature can be converged in a short time. Then, it returns to step S105 (FIG. 10) mentioned above.

  As a result of the comparison in step S108, when the connection state of the coil 3 is not the Y connection (when the delta connection is used), or when the absolute value of the temperature difference ΔT is equal to or less than the threshold value ΔTr (that is, it is necessary to switch to the delta connection). If not, the process returns to step S105.

  When the operation stop signal is received in the above step S105, the rotation of the electric motor 1 is stopped (step S109). Thereafter, the control device 50 switches the connection state of the coil 3 from the Y connection to the delta connection (step S110). When the connection state of the coil 3 is already a delta connection, the connection state is maintained. Although omitted in FIG. 10, also during steps S106 to S108, when the operation stop signal is received, the process proceeds to step S109 and the rotation of the electric motor 1 is stopped.

  Then, the control apparatus 50 performs the stop process of the air conditioner 5 (step S111). Specifically, the fan motors of the indoor fan 47 and the outdoor fan 46 are stopped. Then, CPU57 of the control apparatus 50 stops and the driving | operation of the air conditioner 5 is complete | finished.

  As described above, when the absolute value of the temperature difference ΔT between the room temperature Ta and the set temperature Ts is relatively small (that is, when the absolute value is equal to or less than the threshold value ΔTr), the electric motor 1 is operated with a highly efficient Y connection. When it is necessary to cope with a larger load, that is, when the absolute value of the temperature difference ΔT is larger than the threshold value ΔTr, the electric motor 1 is operated with a delta connection capable of accommodating a larger load. Therefore, the operation efficiency of the air conditioner 5 can be improved.

  In the switching operation from the Y connection to the delta connection (FIG. 12), as shown in FIG. 13 (A), the rotation speed of the motor 1 is detected before step S131 for stopping the rotation of the motor 1 (step S131). In S135, it may be determined whether or not the detected rotation speed is equal to or greater than a threshold value (reference value for rotation speed) (step S136). The rotation speed of the electric motor 1 is detected as the frequency of the output current of the inverter 103.

  In step S136, for example, a rotation speed of 35 rps corresponding to a heating intermediate condition described later and a rotation speed of 85 rps corresponding to a heating rated condition are used as the rotation speed threshold of the electric motor 1. If the rotation speed of the electric motor 1 is equal to or greater than the threshold value, the rotation of the electric motor 1 is stopped, switching to the delta connection is performed, and the bus voltage of the converter 102 is increased (steps S131, S132, S133). If the rotation speed of the electric motor 1 is less than the threshold value, the process returns to step S105 in FIG.

  In this way, in addition to determining whether connection switching is necessary based on the temperature difference ΔT (step S108), by determining whether connection switching is necessary based on the number of rotations of the motor 1, the connection switching is frequently repeated. It can be surely suppressed.

  As shown in FIG. 13B, the output voltage of the inverter 103 is detected before step S131 for stopping the rotation of the electric motor 1 (step S137), and the detected output voltage is a threshold value (reference value of the output voltage). It may be determined whether or not the above is satisfied (step S138).

  FIGS. 13A and 13B show the switching operation from the Y connection to the delta connection. At the time of switching from the delta connection to the Y connection, determination based on the rotation speed of the electric motor 1 or the output voltage of the inverter 103 is performed. May be performed.

  FIG. 14 is a timing chart showing an example of the operation of the air conditioner 5. FIG. 14 shows the operating state of the air conditioner 5 and the driving state of the outdoor blower fan 46 and the electric motor 1 (compressor 41). The outdoor blower fan 46 is shown as an example of a component other than the electric motor 1 of the air conditioner 5.

  When the signal receiving unit 56 receives an operation activation signal (ON command) from the remote controller 55, the CPU 57 is activated and the air conditioner 5 is activated (ON state). When the air conditioner 5 is activated, the fan motor of the outdoor fan 46 starts rotating after the time t0 has elapsed. The time t0 is a delay time due to communication between the indoor unit 5A and the outdoor unit 5B.

  After the start of the air conditioner 5, after the time t1 has elapsed, the rotation of the electric motor 1 by delta connection is started. Time t1 is a waiting time until the rotation of the fan motor of the outdoor fan 46 is stabilized. By rotating the outdoor blower fan 46 before the rotation of the electric motor 1 is started, the temperature of the refrigeration cycle is prevented from rising more than necessary.

  In the example of FIG. 14, switching from the delta connection to the Y connection is performed, and after switching from the Y connection to the delta connection, an operation stop signal (OFF command) is received from the remote controller 55. The time t2 required for switching the connection is a waiting time required for restarting the electric motor 1, and is set to a time required until the refrigerant pressure in the refrigeration cycle becomes substantially equal.

  When the operation stop signal is received from the remote controller 55, the rotation of the electric motor 1 is stopped, and then the rotation of the fan motor of the outdoor fan 46 is stopped after the time t3 has elapsed. Time t3 is a waiting time necessary for sufficiently reducing the temperature of the refrigeration cycle. Thereafter, after time t4 has elapsed, the CPU 57 stops and the air conditioner 5 enters an operation stop state (OFF state). Time t4 is a waiting time set in advance.

<About connection switching based on temperature detection>
In the operation of the air conditioner 5 described above, whether or not the connection state of the coil 3 needs to be switched (steps S107 and S108) can be determined based on, for example, the rotational speed of the electric motor 1 or the inverter output voltage. However, since the rotational speed of the electric motor 1 may fluctuate in a short time, it is necessary to determine whether or not the state where the rotational speed is equal to or lower than the threshold value (or higher than the threshold value) continues for a certain time. The same applies to the inverter output voltage.

  In particular, when the set temperature by the remote controller 55 is greatly changed, or when the load of the air conditioner 5 is suddenly changed by opening a window of the room or the like, it is necessary to switch the connection state of the coil 3. If time is required for the determination, the response of the operation state of the compressor 41 to the load fluctuation is delayed. As a result, the comfort of the air conditioner 5 may be reduced.

  On the other hand, in this embodiment, the temperature difference ΔT (absolute value) between the room temperature Ta detected by the room temperature sensor 54 and the set temperature Ts is compared with a threshold value. Since the temperature hardly fluctuates in a short time, it is not necessary to continue the detection of the temperature difference ΔT and the comparison with the threshold value, and it is possible to determine whether connection switching is necessary in a short time. Therefore, the operation state of the compressor 41 can be made to respond quickly to load fluctuations, and the comfort of the air conditioner 5 can be improved.

  In the operation of the air conditioner 5 described above, the determination of whether or not to switch from the delta connection to the Y connection (step S107) and the determination of whether or not to switch from the Y connection to the delta connection (step S108) are continued. However, switching from the delta connection to the Y connection is performed when the air conditioning load is low (the room temperature is approaching the set temperature), and then the air conditioning load suddenly increases. Therefore, it is unlikely that the connection is frequently switched.

  In the operation of the air conditioner 5 described above, the connection state of the coil 3 is switched (steps S122 and S132) in a state where the rotation of the electric motor 1 is stopped (that is, a state where the output of the inverter 103 is stopped). . Although it is possible to switch the connection state of the coil 3 while continuing to supply power to the electric motor 1, from the viewpoint of the reliability of the relay contacts constituting the switches 61, 62, 63 (FIG. 6) of the connection switching unit 60, It is desirable to perform switching in a state where power supply to the electric motor 1 is stopped.

  It is also possible to switch the connection state of the coil 3 in a state where the rotational speed of the electric motor 1 is sufficiently reduced, and then return to the original rotational speed.

  Here, the switches 61, 62, and 63 of the connection switching unit 60 are configured by relay contacts. However, when configured by a semiconductor switch, it is necessary to stop the rotation of the electric motor 1 when the connection state of the coil 3 is switched. There is no.

  Further, when the state in which the temperature difference ΔT (absolute value) between the room temperature Ta and the set temperature Ts is not more than the threshold value ΔTr is repeated a plurality of times (a preset number of times), the connection state of the coil 3 may be switched. . If it does in this way, it can suppress that connection switching is repeated by a small temperature change.

  As described above, when the temperature difference ΔT between the room temperature and the set temperature becomes 0 or less (ΔT ≦ 0), the control device 50 stops the rotation of the electric motor 1 to prevent overcooling (or overheating). The connection state of the coil 3 may be switched from the delta connection to the Y connection at this timing. Specifically, in step S107 described above, it is determined whether or not the temperature difference ΔT is 0 or less. If the temperature difference ΔT is 0 or less, the rotation of the motor 1 is stopped and the connection state of the coil 3 is changed to Y. What is necessary is just to switch to a connection.

  In the operation of the air conditioner 5 described above, since the bus voltage of the converter 102 is boosted when switching from the Y connection to the delta connection, a high torque can be generated by the electric motor 1. Therefore, the difference ΔT between the room temperature and the set temperature can be converged in a shorter time. The boosting of the bus voltage of converter 102 will be described later.

<About the connection status at startup>
As described above, when the air conditioner 5 according to Embodiment 1 receives the operation start signal and starts the electric motor 1, the air conditioner 5 starts control with the connection state of the coil 3 as the delta connection. Further, when the operation of the air conditioner 5 is stopped, the connection state of the coil 3 is switched to the delta connection.

  When the operation of the air conditioner 5 is started, it is difficult to accurately detect the air conditioning load. In particular, when the operation of the air conditioner 5 is started, the difference between the room temperature and the set temperature is generally large and the air conditioning load is generally large. Therefore, in the first embodiment, the electric motor 1 is activated in a state where the connection state of the coil 3 is a delta connection that can cope with a larger load (that is, can rotate to a higher rotational speed). Thereby, at the start of operation of the air conditioner 5, the difference ΔT between the room temperature Ta and the set temperature Ts can be converged in a shorter time.

  In addition, when the air conditioner 5 is stopped for a long period of time and an abnormality occurs in the connection switching unit 60 during the stop (for example, the relays of the switches 61 to 63 are stuck and do not operate), the air conditioner 5 Since the switching from the Y connection to the delta connection is performed before the operation is stopped, the electric motor 1 can be started by the delta connection. For this reason, it is possible to prevent the performance of the air conditioner 5 from being lowered, and the comfort is not impaired.

  In addition, when the motor 1 is started with the connection state of the coil 3 as the delta connection and the switching to the Y connection is not performed, the connection state of the coil is always the delta connection (no connection switching function) Motor efficiency equivalent to that of a simple motor can be obtained.

<Motor efficiency and motor torque>
Next, improvements in motor efficiency and motor torque will be described. In general, home air conditioners are regulated by the Energy Conservation Law, and CO ₂ emission reduction is obligated from the viewpoint of the global environment. Advances in technology have improved the compression efficiency of the compressor, the operating efficiency of the motor of the compressor, the heat transfer rate of the heat exchanger, etc., and the energy consumption efficiency COP (Coefficient of Performance) of the air conditioner has improved year by year. Running costs (power consumption) and CO ₂ emissions are also reduced.

  The COP evaluates the performance when operated under a certain temperature condition, and does not take into account the operating condition of the air conditioner according to the season. However, during actual use of the air conditioner, the capacity and power consumption required for cooling or heating change due to changes in the outside air temperature. Therefore, in order to evaluate in a state close to actual use, a certain model case is determined, the total load and the total power consumption throughout the year are calculated, and the APF (Annual Performance Factor) for obtaining the efficiency is It is used as an index for energy saving.

  In particular, the current mainstream inverter motor has a problem in performing an evaluation close to actual use only under rated conditions because the capacity varies depending on the rotation speed of the compressor.

  The APF of a home air conditioner calculates the amount of power consumption according to the annual total load at five evaluation points of cooling rating, cooling middle, heating rating, heating middle, and heating low temperature. The larger this value, the higher the energy saving performance.

  As a breakdown of annual total load, the ratio of heating intermediate conditions is very large (50%), and then the ratio of heating rated conditions is large (25%). Therefore, improving the motor efficiency in the heating intermediate condition and the heating rated condition is effective for improving the energy saving performance of the air conditioner.

  The rotation speed of the compressor motor under the APF evaluation load condition varies depending on the capacity of the air conditioner and the performance of the heat exchanger. For example, in a home air conditioner having a refrigeration capacity of 6.3 kW, the rotation speed N1 (first rotation speed) under the heating intermediate condition is 35 rps, and the rotation speed N2 (second rotation) under the heating rated condition Number) is 85 rps.

  The electric motor 1 of this embodiment is intended to obtain high electric motor efficiency and electric motor torque at the rotational speed N1 corresponding to the heating intermediate condition and the rotational speed N2 corresponding to the heating rated condition. That is, of the two load conditions that are targets for performance improvement, the low-speed rotation speed is N1, and the high-speed rotation speed is N2.

  In the electric motor 1 in which the permanent magnet 25 is mounted on the rotor 20, when the rotor 20 rotates, the magnetic flux of the permanent magnet 25 is linked to the coil 3 of the stator 10, and an induced voltage is generated in the coil 3. The induced voltage is proportional to the number of rotations (rotational speed) of the rotor 20 and is also proportional to the number of turns of the coil 3. The induced voltage increases as the number of rotations of the electric motor 1 increases and the number of turns of the coil 3 increases.

  The line voltage (motor voltage) output from the inverter 103 is equal to the sum of the induced voltage and the voltage generated by the resistance and inductance of the coil 3. Since the resistance and inductance of the coil 3 are negligibly small compared to the induced voltage, the line voltage is effectively controlled by the induced voltage. The magnet torque of the electric motor 1 is proportional to the product of the induced voltage and the current flowing through the coil 3.

  The induced voltage increases as the number of turns of the coil 3 increases. Therefore, as the number of turns of the coil 3 is increased, the current for generating the necessary magnet torque can be reduced. As a result, loss due to energization of the inverter 103 can be reduced and the operating efficiency of the electric motor 1 can be improved. On the other hand, as the induced voltage rises, the line voltage governed by the induced voltage reaches the inverter maximum output voltage (that is, the bus voltage supplied from the converter 102 to the inverter 103) at a lower rotational speed, and the rotational speed is reduced. It can't be faster.

  Further, when the number of turns of the coil 3 is reduced, the induced voltage is lowered, so that the line voltage governed by the induced voltage does not reach the inverter maximum output voltage up to a higher rotational speed, and high-speed rotation is possible. However, since the current for generating the necessary magnet torque increases due to the reduction of the induced voltage, the loss due to energization of the inverter 103 increases, and the operating efficiency of the electric motor 1 decreases.

  Further, in terms of the switching frequency of the inverter 103, the harmonic component due to the ON / OFF duty of switching of the inverter 103 decreases when the line voltage is closer to the inverter maximum output voltage. The resulting iron loss can be reduced.

  15 and 16 are graphs showing the relationship between the line voltage and the rotation speed in the electric motor 1. The connection state of the coil 3 is a Y connection. The line voltage is proportional to the product of the field magnetic field and the rotational speed. If the field magnetic field is constant, the line voltage and the rotation speed are proportional as shown in FIG. In FIG. 15, the rotation speed N1 corresponds to the heating intermediate condition, and the rotation speed N2 corresponds to the heating rated condition.

  The line voltage increases with the increase in the number of revolutions. However, as shown in FIG. 16, when the line voltage reaches the inverter maximum output voltage, the line voltage cannot be further increased. Is started. Here, it is assumed that field-weakening control is started at a rotational speed between rotational speeds N1 and N2.

  In the field weakening control, the induced voltage is weakened by passing a current having a d-axis phase (direction in which the magnetic flux of the permanent magnet 25 is canceled) through the coil 3. This current is referred to as a weakening current. Since it is necessary to flow a weak current in addition to the current for generating the normal motor torque, the copper loss due to the resistance of the coil 3 increases and the conduction loss of the inverter 103 also increases.

  FIG. 17 is a graph showing the relationship between the motor efficiency and the rotation speed when the field weakening control shown in FIG. 16 is performed. As shown in FIG. 17, the motor efficiency increases with the rotation speed, and immediately after starting the field weakening control, the motor efficiency reaches a peak as indicated by an arrow P.

  As the number of rotations further increases, the weakening current that flows through the coil 3 also increases, thereby increasing the copper loss and lowering the motor efficiency. Note that a change represented by a curve similar to FIG. 17 is also seen in the overall efficiency, which is the product of the motor efficiency and the inverter efficiency.

  FIG. 18 is a graph showing the relationship between the maximum torque and the rotational speed of the electric motor when the field weakening control shown in FIG. 16 is performed. Before starting the field weakening control, the maximum torque of the motor is constant (for example, due to a restriction by the current threshold). When field-weakening control is started, the maximum torque of the electric motor 1 decreases with an increase in the rotational speed. The maximum torque of the electric motor 1 is set to be larger than the load (necessary load) actually generated by the electric motor 1 when the product is used. Hereinafter, for convenience of explanation, the maximum torque of the electric motor is referred to as electric motor torque.

  FIG. 19 is a graph showing the relationship between the line voltage and the rotational speed for each of the Y connection and the delta connection. The phase impedance of the coil 3 when the connection state of the coil 3 is a delta connection is 1 / √3 times that when the connection state of the coil 3 is a Y connection when the number of turns is the same. Therefore, the interphase voltage (dotted line) when the connection state of the coil 3 is a delta connection is 1 / √ of the interphase voltage (solid line) when the connection state of the coil 3 is a Y connection when the rotation speed is the same. Tripled.

  That is, when the coil 3 is connected by delta connection, if the number of turns is √3 times that of Y connection, the line voltage (motor voltage) is equivalent to that of Y connection for the same rotation speed N. Therefore, the output current of the inverter 103 is also equivalent to the case of Y connection.

  In an electric motor in which the number of windings on the teeth is several tens or more, the Y connection is often used rather than the delta connection for the following reason. One reason is that since the delta connection has a larger number of coil turns than the Y connection, the time required for winding the coil in the manufacturing process becomes longer. Another reason is that a circulating current may be generated in the case of delta connection.

  In general, in a motor employing Y connection, the line voltage (motor voltage) reaches the inverter maximum output voltage at the rotation speed N2 (that is, the rotation speed on the high speed side among the rotation speeds targeted for performance improvement). In addition, the number of turns of the coil is adjusted. However, in this case, the motor is operated in a state where the line voltage is lower than the inverter maximum output voltage at the rotation speed N1 (that is, the low-speed rotation speed among the rotation speeds targeted for performance improvement). It is difficult to obtain high motor efficiency.

  Therefore, the coil connection state is set to Y connection, the number of turns is adjusted so that the line voltage reaches the inverter maximum output voltage at a number of revolutions slightly lower than the number of revolutions N1, and the time until the number of revolutions N2 is reached. The control of switching the connection state of the coil to the delta connection is performed.

  FIG. 20 is a graph showing the relationship between the line voltage and the rotation speed when switching from the Y connection to the delta connection. In the example shown in FIG. 20, when the rotational speed reaches slightly lower than the rotational speed N1 (heating intermediate condition) (the rotational speed is N11), the above-described field weakening control is started. When the rotational speed N further increases and reaches the rotational speed N0, switching from the Y connection to the delta connection is performed. Here, the rotational speed N11 is 5% lower than the rotational speed N1 (that is, N11 = N1 × 0.95).

  By switching to the delta connection, the line voltage decreases to 1 / √3 times that of the Y connection, so that the field weakening can be suppressed to a small extent (that is, the weakening current can be reduced). Thereby, the copper loss resulting from the weak current can be suppressed, and the reduction of the motor efficiency and the motor torque can be suppressed.

  FIG. 21 is a graph showing the relationship between the motor efficiency and the rotation speed for each of the Y connection and the delta connection. Since the connection state of the coil 3 is set to the Y connection as described above, and the number of turns is adjusted so that the line voltage reaches the inverter maximum output voltage at the rotation speed N11 slightly lower than the rotation speed N1, FIG. As indicated by the solid line, high motor efficiency is obtained at the rotational speed N1.

  On the other hand, if the number of turns of the coil 3 is the same, in the case of delta connection, as shown by a one-dot chain line in FIG. 21, higher motor efficiency is obtained at the rotation speed N2 than in the case of Y connection. Therefore, if the Y connection is switched to the delta connection at the intersection of the solid line and the alternate long and short dash line shown in FIG. 21, high motor efficiency can be obtained at both the rotational speed N1 (heating intermediate condition) and the rotational speed N2 (heating rated condition).

  Therefore, as described with reference to FIG. 20, the connection state of the coil 3 is Y connection, and the line voltage becomes the inverter maximum output voltage at the rotation speed N11 (the rotation speed slightly lower than the rotation speed N1). The number of turns is adjusted so as to reach, and control is performed to switch from the Y connection to the delta connection at a rotation speed N0 higher than the rotation speed N1.

  However, simply switching the connection state of the coil 3 from the Y connection to the delta connection cannot sufficiently improve the motor efficiency. This will be described below.

  In FIG. 22, the connection state of the coil 3 is Y connection, the winding number is adjusted so that the line voltage reaches the inverter maximum output voltage at the rotation speed N11, and the Y connection is switched from the Y connection to the delta connection at the rotation speed N0. It is a graph which shows the relationship between the motor efficiency of a case (solid line), and rotation speed. In addition, a broken line is a graph which shows the relationship between the motor efficiency and rotation speed at the time of performing field-weakening control by making the connection state of the coil 3 into Y connection as shown in FIG.

  The line voltage is proportional to the rotation speed. For example, in a home air conditioner having a refrigeration capacity of 6.3 kW, the rotation speed N1 (heating intermediate condition) is 35 rps and the rotation speed N2 (heating rated condition) is 85 rps. As a reference, the line voltage under the heating rated condition is 2.4 times (= 85/35).

  After switching the connection state of the coil 3 to the delta connection, the line voltage under the heating rated condition (rotation speed N2) is 1.4 times (= 85/35 / √3) with respect to the inverter maximum output voltage. . Since the line voltage cannot be made larger than the maximum output voltage of the inverter, field weakening control is started.

  In the field weakening control, a weakening current necessary for weakening the field is passed through the coil 3, so that the copper loss increases and the motor efficiency and the motor torque decrease. Therefore, as shown by the solid line in FIG. 22, the motor efficiency under the heating rated condition (rotation speed N2) cannot be improved.

  In order to suppress the degree of field weakening under the heating rated condition (rotation speed N2) (reduce the weakening current), it is necessary to reduce the number of turns of the coil 3 to lower the interphase voltage. The interphase voltage in the heating intermediate condition (rotation speed N1) also decreases, and the effect of improving the motor efficiency by switching the connection is reduced.

  That is, when there are two load conditions for performance improvement, and the rotation speed N1 on the low speed side and the rotation speed N2 on the high speed side satisfy (N2 / N1)> √3, from the Y connection Even if switching to the delta connection, field-weakening control is required. Therefore, a sufficient improvement effect of the motor efficiency cannot be obtained simply by switching from the Y connection to the delta connection.

  FIG. 23 is a graph showing the relationship between the motor torque and the rotational speed for each of the Y connection and the delta connection. In the case of Y connection, as described with reference to FIG. 18, the motor torque is constant with respect to the increase in the rotational speed N, but when field weakening control is started, the motor torque is increased with the increase in the rotational speed N. Decreases. In the case of delta connection, field weakening control is started at a higher rotational speed than in the case of Y connection (N11). When field weakening control is started, the motor torque decreases as the rotational speed N increases.

  FIG. 24 shows that the connection state of the coil 3 is Y-connection, and the number of turns is adjusted so that the line voltage reaches the inverter maximum output voltage at the rotation speed N11 (the rotation speed slightly lower than the rotation speed N1). It is a graph which shows the relationship between the motor torque at the time of switching from Y connection to delta connection at the rotation speed N0 higher than rotation speed N1, and rotation speed. As shown in FIG. 24, when the rotational speed reaches the rotational speed N11 and field weakening control is started, the motor torque decreases as the rotational speed N increases.

  When the number of rotations further increases and reaches the number of rotations N0 and switching from the Y connection to the delta connection is performed, the field weakening control is temporarily stopped, and the motor torque increases. However, when the rotational speed N further increases and field-weakening control is started, the motor torque decreases as the rotational speed N increases. Thus, simply switching from the Y connection to the delta connection cannot suppress a reduction in motor torque, particularly in the high rotation speed range.

  In view of this, the driving apparatus 100 according to the first embodiment switches the bus voltage by the converter 102 in addition to switching the connection state of the coil 3 by the connection switching unit 60. The converter 102 is supplied with a power supply voltage (200 V) from the power supply 101 and supplies a bus voltage to the inverter 103. It is desirable that converter 102 be composed of an element with a small loss accompanying voltage rise (boost), for example, an SiC element or a GaN element.

  Specifically, the bus voltage V1 (first bus voltage) when the connection state of the coil 3 is the Y connection is set to 280 V (DC). On the other hand, the bus voltage V2 (second bus voltage) when the connection state of the coil 3 is a delta connection is set to 390 V (DC). That is, the bus voltage V2 in the case of delta connection is set to 1.4 times the bus voltage V1 in the case of Y connection. The bus voltage V2 may be V2 ≧ (V1 / √3) × N2 / N1 with respect to the bus voltage V1. The inverter 103 supplied with the bus voltage from the converter 102 supplies the line voltage to the coil 3. The inverter maximum output voltage is 1 / √2 of the bus voltage.

  FIG. 25 is a graph showing the relationship between the line voltage and the rotational speed when the bus voltage is switched by the converter 102 for each of the Y connection and the delta connection. As shown in FIG. 25, the line voltage (solid line) when the connection state of the coil 3 is Y connection is 1 / √2 (that is, V1 × 1 / √2) of the bus voltage V1 at the maximum. When the connection state of the coil 3 is a delta connection, the line voltage (one-dot chain line) is 1 / √2 (that is, V2 × 1 / √2) of the bus voltage V2 at the maximum.

  FIG. 26 is a graph showing the relationship between the line voltage and the rotation speed when the connection state is switched by the connection switching unit 60 and the bus voltage is switched by the converter 102. As shown in FIG. 26, in the rotation speed range including the rotation speed N1 (heating intermediate condition), the connection state of the coil 3 is the Y connection. The line voltage increases with the increase in the number of revolutions, and the line voltage reaches the inverter maximum output (V1 × 1 / √2) at the number of revolutions N11 slightly lower than the number of revolutions N1. Thereby, field weakening control is started.

  When the rotational speed further increases and reaches the rotational speed N0, the connection switching unit 60 switches the connection state of the coil 3 from the Y connection to the delta connection. At the same time, converter 102 boosts the bus voltage from V1 to V2. By boosting, the maximum inverter output becomes V2 × 1 / √2. At this time, since the interphase voltage is lower than the inverter maximum output, the field-weakening control is not performed.

  Thereafter, the line voltage increases as the rotation speed N increases, and the line voltage reaches the inverter maximum output (V2 × 1 / √2) at the rotation speed N21 slightly lower than the rotation speed N2 (heating rated condition). This starts field weakening control. The rotation speed N21 is 5% lower than the rotation speed N2 (that is, N21 = N2 × 0.95).

  In the first embodiment, as described above, the connection state of the coil 3 is switched based on the comparison result between the temperature difference ΔT between the room temperature Ta and the set temperature Ts and the threshold value ΔTr. The switching from the Y connection to the delta connection at the rotational speed N0 corresponds to the switching from the Y connection to the delta connection shown in step S108 in FIG. 10 and steps S131 to S134 in FIG.

  The effect of improving the motor efficiency in this case will be described. FIG. 27 is a graph showing the relationship between the motor efficiency and the rotational speed for each of the Y connection and the delta connection. In FIG. 27, the motor efficiency (solid line) when the connection state of the coil 3 is the Y connection is the same as the motor efficiency in the Y connection shown in FIG. On the other hand, the motor efficiency (one-dot chain line) in the case where the connection state of the coil 3 is a delta connection is higher than the motor efficiency in the delta connection shown in FIG. 21 because the bus voltage of the converter 102 increases.

  FIG. 28 is a graph showing the relationship between the motor efficiency and the number of revolutions when the connection state is switched by the connection switching unit 60 and the bus voltage is switched by the converter 102. Since the connection state of the coil 3 is Y-connection, and the number of turns is set so that the line voltage reaches the inverter maximum output voltage at the rotation speed N11 (rotation speed slightly lower than the rotation speed N1). High motor efficiency can be obtained in the rotational speed range including the number N1.

  When the number of revolutions reaches the number of revolutions N11, field-weakening control is started. When the number of revolutions reaches N0, the connection state of the coil 3 is switched from the Y connection to the delta connection, and the bus voltage is increased by the converter 102. To do.

  Since the inverter maximum output voltage also rises due to the rise of the bus voltage, the line voltage becomes lower than the inverter maximum output voltage, and as a result, field weakening control stops. By stopping the field weakening control, the copper loss due to the field weakening current is reduced, so that the motor efficiency is increased.

  Further, when the rotation speed N reaches the rotation speed N21 that is slightly smaller than the rotation speed N2 (heating rating condition), the line voltage reaches the inverter maximum output voltage, and field weakening control is started. Although the copper loss increases due to the start of the field weakening control, a high motor efficiency can be obtained because the bus voltage is increased by the converter 102.

  That is, as shown by a solid line in FIG. 28, high motor efficiency can be obtained at both the rotational speed N1 (heating intermediate condition) and the rotational speed N2 (heating rated condition).

  Next, the effect of improving the motor torque will be described. FIG. 29 is a graph showing the relationship between the motor torque and the rotational speed for each of the case where the connection state of the coil 3 is the Y connection and the delta connection. The motor torque (solid line) in the case of Y connection is the same as that in FIG. When the field weakening control is started at the rotational speed N21 slightly lower than the rotational speed N2 (heating rated condition), the electric motor torque (one-dot chain line) in the case of the delta connection decreases as the rotational speed N increases.

  FIG. 30 shows that the connection state of the coil 3 is Y connection, the winding number is adjusted so that the line voltage reaches the inverter maximum output voltage at the rotation speed N11, and the delta from the Y connection at the rotation speed N0 (> N1). It is a graph which shows the relationship between the motor torque at the time of switching to a connection and raising the bus-line voltage further, and rotation speed. As shown in FIG. 30, when field-weakening control is started at a rotational speed N11 slightly lower than the rotational speed N1 (heating intermediate condition), the motor torque decreases as the rotational speed N increases.

  When the rotation speed N further increases and reaches the rotation speed N0, the connection state of the coil 3 is switched from the Y connection to the delta connection, and the bus voltage further increases. Since the line voltage becomes lower than the inverter maximum output voltage due to the switching to the delta connection and the rise of the bus voltage, the field-weakening control is stopped. As a result, the motor torque increases. Thereafter, when field-weakening control is started at a rotational speed N21 slightly lower than the rotational speed N2 (heating rated condition), the motor torque decreases as the rotational speed N increases.

  In this way, after switching to the delta connection, field-weakening control is not performed until the rotational speed N reaches the rotational speed N21 (the rotational speed slightly smaller than the rotational speed N2). ), The reduction of the motor torque can be suppressed.

  That is, as shown by a solid line in FIG. 30, high motor torque is obtained at both the rotational speed N1 (heating intermediate condition) and the rotational speed N2 (heating rated condition). That is, high performance (motor efficiency and motor torque) can be obtained in both the heating intermediate condition and the heating rated condition of the air conditioner 5.

  When the voltage of the converter 102 is boosted, a loss due to the boosting is generated. Therefore, the power supply voltage is used without being boosted in the connection state in the heating intermediate condition (that is, the Y connection) having the largest contribution ratio to the motor efficiency. It is preferable to do. The power supply voltage of the power supply 101 is 200 V (effective value), and the maximum value is 280 V (= 200 V × √2). Therefore, it can be said that the bus voltage (280 V) of converter 102 in the case of Y connection is the same as the maximum value of the power supply voltage.

  The bus voltage supplied to the inverter 103 may be switched by boosting or lowering the power supply voltage.

  Further, in the operation control of the air conditioner 5 described above, Y connection is made at the rotational speed N1 (heating intermediate condition) and delta connection is made at the rotational speed N2 (heating rated condition), but specific load conditions are not decided. In this case, the voltage level may be adjusted with the rotation speed N1 as the maximum rotation speed operated with the Y connection and the rotation speed N2 as the maximum rotation speed operated with the delta connection. Even if it controls in this way, the efficiency of the electric motor 1 can be improved.

  As described above, in the home air conditioner 5, the efficiency of the electric motor 1 can be improved by setting the rotation speed N <b> 1 to the rotation speed of the heating intermediate condition and the rotation speed N <b> 2 to the rotation speed of the heating rated condition. it can.

<Effect of Embodiment 1>
As described above, in the first embodiment, since the connection state of the coil 3 is switched based on the room temperature Ta, the connection state can be switched in a short time. Therefore, for example, the operating state of the compressor 41 can be quickly dealt with against a sudden load fluctuation of the air conditioner 5 such as when a room window is opened, and the comfort can be improved.

  In addition, since the rotation of the electric motor 1 is stopped before the connection state of the coil 3 is switched, the reliability of the connection switching operation can be ensured even when the connection switching unit 60 is configured with a relay contact.

  Moreover, since the connection state of the coil 3 is switched between the Y connection (first connection state) and the delta connection (second connection state) having a lower line voltage than the first connection state, the rotation of the motor 1 The connection state suitable for the number can be selected.

  Further, when the absolute value of the difference (temperature difference ΔT) between the room temperature Ta detected by the room temperature sensor 54 and the set temperature Ts is larger than the threshold value ΔTr, the connection state of the coil 3 is changed to the delta connection (second connection state). Therefore, when the air conditioning load is large, the number of revolutions of the electric motor 1 can be increased and a high output can be generated.

  Moreover, when the absolute value of temperature difference (DELTA) T is below threshold value (DELTA) Tr, since the connection state of the coil 3 is switched to a Y connection (1st connection state), the operating efficiency when an air-conditioning load is low can be improved. .

  Further, in each of the Y connection (first connection state) and the delta connection (second connection state), field weakening control is performed according to the number of revolutions of the motor 1, so that the line voltage reaches the inverter maximum output voltage. Also, the rotational speed of the electric motor 1 can be increased.

  In addition, since the converter 102 changes the magnitude of the bus voltage in accordance with the switching of the connection state of the coil 3 by the connection switching unit 60, high motor efficiency and high motor torque are obtained both before and after switching of the connection state. Obtainable.

  In addition to comparing the difference between the room temperature Ta and the set temperature Ts and the threshold value, the rotational speed of the electric motor 1 is compared with a reference value, and the connection state of the coil 3 is switched based on the comparison result. , It is possible to effectively suppress frequent connection switching.

  In addition to the comparison between the room temperature Ta and the set temperature Ts, if the output voltage of the inverter 103 is compared with a reference value and the connection state of the coil 3 is switched based on the comparison result, the connection switching is frequent. Can be effectively suppressed.

  Further, when the control device 50 receives an operation stop signal from the remote controller 55 via the signal receiving unit 56, the control device 50 is connected to the air conditioner 5 after the connection state of the coil 3 is switched from the Y connection to the delta connection. End driving. When the connection state of the coil 3 is already a delta connection, the connection state is maintained. Therefore, when the operation of the air conditioner 5 is started (starting up), the operation of the air conditioner 5 can be started with the connection state of the coil 3 being in the delta connection state. Thereby, even when the temperature difference ΔT between the room temperature Ta and the set temperature Ts is large, the operation of the air conditioner 5 can be started in a delta connection state, and the room temperature Ta is quickly brought close to the set temperature Ts. Can do.

First modification.
Next, a first modification of the first embodiment will be described. In the first embodiment, the rotational speed N0 (that is, the rotational speed when the temperature difference ΔT and the threshold value ΔTr are the same) is switched from the Y connection to the delta connection, and the delta connection is changed to the Y connection. Although the rotation speed N0 (temperature difference) to be switched is the same, a different rotation speed may be used.

  FIGS. 31A and 31B are graphs showing the relationship between the motor efficiency and the number of revolutions when the connection state is switched by the connection switching unit 60 and the bus voltage is switched by the converter 102. FIG. As shown in FIGS. 31A and 31B, the rotational speed N4 for switching the connection state of the coil 3 from the Y connection to the delta connection is different from the rotational speed N5 for switching from the delta connection to the Y connection.

  The switching of the bus voltage by the converter 102 is performed simultaneously with the switching of the connection state of the coil 3. That is, the bus voltage is boosted at the rotational speed N4 at which the Y connection is switched to the delta connection. On the other hand, at the rotation speed N5 where the delta connection is switched to the Y connection, the bus voltage is stepped down.

  Such control can be executed, for example, by setting the threshold value ΔTr in step S107 in FIG. 10 and the threshold value ΔTr in step S108 to different values. In the example shown in FIGS. 31A and 31B, the rotation speed N4 for switching from the Y connection to the delta connection is larger than the rotation speed N5 for switching from the delta connection to the Y connection, but the magnitude may be reversed. . Other operations and configurations in the first modification are the same as those in the first embodiment.

  Also in the first modification, the operating state of the compressor 41 can be made to respond quickly to sudden load fluctuations of the air conditioner 5 by switching the connection state of the coil 3 based on the room temperature Ta. Can do. Moreover, high motor efficiency can be obtained by switching the bus voltage of the converter 102 in accordance with switching of the connection state of the coil 3.

Second modification.
Next, a second modification of the first embodiment will be described. In Embodiment 1 described above, the bus voltage of converter 102 is switched to two stages (V1 / V2), but may be switched to three stages as shown in FIG.

  FIG. 32 is a graph showing the relationship between the line voltage and the rotation speed when the connection state is switched and the bus voltage of the converter 102 is switched in the second modification. In the example of FIG. 32, at the rotation speed N1 (Y connection) corresponding to the heating intermediate condition, the bus voltage of the converter 102 is V1, and the rotation speed N6 between the rotation speed N1 and the rotation speed N2 (heating rated condition) The Y connection is switched to the delta connection, and at the same time, the bus voltage is boosted to V2.

  Further, at the rotation speed N7 higher than the rotation speed N2, the bus voltage of the converter 102 is boosted to V3 while maintaining the connection state. From this rotational speed N7 to the maximum rotational speed N8, the bus voltage of the converter 102 is V3. Other operations and configurations in the second modification are the same as those in the first embodiment.

  As described above, in the second modification, the bus voltage of the converter 102 is switched to the three stages of V1, V2, and V3, so that high motor efficiency and high motor torque can be obtained particularly in the high rotation speed range. .

  The bus voltage switching is not limited to two steps or three steps, and may be four steps or more. In the first modification (FIG. 31), the bus voltage of converter 102 may be switched between three or more stages.

Third modification.
Next, a third modification of the first embodiment will be described. In the first embodiment, the connection state of the coil 3 is switched between the Y connection and the delta connection. However, the connection state of the coil 3 may be switched between a series connection as the first connection state and a parallel connection as the second connection state.

  FIGS. 33A and 33B are schematic diagrams for explaining switching of the connection state of the coil 3 of the third modified example. In FIG. 33A, the three-phase coils 3U, 3V, and 3W are connected by Y connection. Further, the coil portions Ua, Ub, Uc of the coil 3U are connected in series, the coil portions Va, Vb, Vc of the coil 3V are connected in series, and the coil portions Wa, Wb, Wc of the coil 3W are connected in series. Yes. That is, the coil 3 that is a three-phase coil is connected in series for each phase.

  On the other hand, in FIG. 33B, the three-phase coils 3U, 3V, 3W are connected by Y connection, but the coil portions Ua, Ub, Uc of the coil 3U are connected in parallel, and the coil portion Va of the coil 3V is connected. , Vb, Vc are connected in parallel, and coil portions Wa, Wb, Wc of the coil 3W are connected in parallel. That is, the coil 3 that is a three-phase coil is connected in parallel for each phase. The switching of the connection state of the coil 3 shown in FIGS. 33A and 33B can be realized by providing a changeover switch in each coil portion of the coils 3U, 3V, 3W, for example.

  When the number of coil portions (that is, the number of columns) connected in parallel in each phase is n, the line voltage is 1 by switching from the series connection (FIG. 33A) to the parallel connection (FIG. 33B). / N times. Therefore, when the line voltage approaches the inverter maximum output voltage, the degree of field weakening can be reduced (that is, the current weakening can be reduced) by switching the connection state of the coil 3 from series connection to parallel connection. it can.

  If there are two load conditions for performance improvement and the low-speed rotation speed N1 and the high-speed rotation speed N2 satisfy (N2 / N1)> n, the connection state of the coil 3 is Since the line voltage becomes larger than the inverter maximum output voltage simply by switching from the series connection to the parallel connection, field-weakening control is required. Therefore, as described in the first embodiment, the connection state of the coil 3 is switched from serial connection to parallel connection, and at the same time, the bus voltage of the converter 102 is boosted. As a result, high motor efficiency and high motor torque can be obtained in both the rotational speed range including the rotational speed N1 and the rotational speed range including the rotational speed N2.

  FIGS. 34A and 34B are schematic views for explaining another configuration example of the third modification. In FIG. 34A, the three-phase coils 3U, 3V, and 3W are connected by delta connection. Further, the coil portions Ua, Ub, Uc of the coil 3U are connected in series, the coil portions Va, Vb, Vc of the coil 3V are connected in series, and the coil portions Wa, Wb, Wc of the coil 3W are connected in series. Yes. That is, the coil part of each phase of the coil 3 is connected in series.

  On the other hand, in FIG. 34B, the three-phase coils 3U, 3V, 3W are connected by delta connection, but the coil portions Ua, Ub, Uc of the coil 3U are connected in parallel, and the coil portion Va of the coil 3V is connected. , Vb, Vc are connected in parallel, and coil portions Wa, Wb, Wc of the coil 3W are connected in parallel. That is, the coil portions of the respective phases of the coil 3 are connected in parallel.

  In this case as well, as in the example shown in FIGS. 33A and 33B, of the two load conditions targeted for performance improvement, the low-speed rotation speed N1 and the high-speed rotation speed N2 are ( When N2 / N1)> n is satisfied, the connection state of the coil 3 is switched from the series connection (FIG. 33A) to the parallel connection (FIG. 33B), and the bus voltage of the converter 102 is boosted at the same time. Other operations and configurations in the third modification are the same as those in the first embodiment. The bus voltage V2 after boosting may be V2 ≧ (V1 / n) × N2 / N1 with respect to the bus voltage V1 before boosting.

  As described above, in the third modified example, by switching the connection state of the converter 102 between the series connection and the parallel connection, it is possible to suppress the degree of field weakening and to improve the motor efficiency. Further, when the bus voltage V1, V2 and the rotational speeds N1, N2 satisfy V2 ≧ (V1 / n) × N2 / N1, high motor efficiency and motor torque can be obtained at the rotational speeds N1, N2.

  In the first modification and the second modification, the series connection (first connection state) and the parallel connection (second connection state) may be switched.

Fourth modification.
In the first embodiment described above, the absolute value of the difference ΔT between the room temperature Ta detected by the room temperature sensor 54 and the set temperature Ts is compared with the threshold value ΔTr, and the connection state of the coil 3 and the bus voltage of the converter 102 are switched. However, the air conditioning load may be calculated based on the room temperature Ta, and the connection state of the coil 3 and the bus voltage of the converter 102 may be switched based on the air conditioning load.

  FIG. 35 is a flowchart showing the basic operation of the air conditioner of the fourth modified example. Steps S101 to S105 are the same as those in the first embodiment. If the operation stop signal is not received after starting the motor 1 in step S104 (step S105), the control device 50 detects the indoor temperature Ta detected by the indoor temperature sensor 54 and the set temperature Ts set by the remote controller 55. Is obtained (step S201), and the air conditioning load is calculated based on the temperature difference ΔT (step S202).

  Next, based on the calculated air conditioning load, it is determined whether or not switching from the delta connection to the Y connection of the coil 3 is necessary. That is, it is determined whether the connection state of the coil 3 is a delta connection and the air conditioning load calculated in step S202 is equal to or less than a threshold value (reference value of the air conditioning load) (step S203).

  As a result of the comparison in step S203, if the connection state of the coil 3 is a delta connection and the air conditioning load is equal to or less than the threshold value, the processes of steps S121 to S124 shown in FIG. 11 are performed. In steps S121 to S124 in FIG. 11, as described in the first embodiment, switching from the delta connection to the Y connection and boosting of the bus voltage by the converter 102 are performed.

  As a result of the comparison in step S203, when the connection state of the coil 3 is not delta connection (when it is Y connection), or when the air conditioning load is larger than the threshold (that is, when it is not necessary to switch to Y connection), Proceed to step S204.

  In step S204, it is determined whether or not switching from the Y connection to the delta connection is necessary. That is, it is determined whether the connection state of the coil 3 is the Y connection and the air conditioning load calculated in step S202 is greater than the threshold value.

  As a result of the comparison in step S204, if the connection state of the coil 3 is Y-connection and the air conditioning load is larger than the threshold value, the processing in steps S131 to S134 shown in FIG. 12 is performed. In steps S131 to S134 in FIG. 12, as described in the first embodiment, switching from the Y connection to the delta connection and the step-down of the bus voltage by the converter 102 are performed.

  As a result of the comparison in step S204, when the connection state of the coil 3 is not Y connection (when delta connection), or when the air conditioning load is larger than a threshold value (that is, when it is not necessary to switch to delta connection), The process returns to step S105. The processing (steps S109 to S111) when the operation stop signal is received is the same as that in the first embodiment. Other operations and configurations in the fourth modification are the same as those in the first embodiment.

  Thus, in the fourth modification, the air conditioning load is calculated based on the room temperature Ta, and the connection state of the coil 3 and the bus voltage of the converter 102 are switched based on the calculated air conditioning load. Thus, the operating state of the compressor 41 can be quickly responded to the load fluctuation of 5, and the comfort can be improved.

  In the first modification, the second modification, and the third modification, the connection state of the coil 3 and the bus voltage of the converter 102 may be switched based on the air conditioning load.

Fifth modification.
In the first embodiment described above, the connection state of the coil 3 and the bus voltage of the converter 102 are switched based on the temperature difference ΔT between the room temperature Ta detected by the room temperature sensor 54 and the set temperature Ts. The connection state of the coil 3 and the bus voltage of the converter 102 may be switched based on the number.

  FIG. 36 is a flowchart showing the basic operation of the air conditioner of the fifth modified example. Steps S101 to S105 are the same as those in the first embodiment. After starting the electric motor 1 in step S104, if the operation stop signal has not been received (step S105), the control device 50 acquires the rotational speed of the electric motor 1 (step S301). The rotation speed of the electric motor 1 is the frequency of the output current of the inverter 103 and can be detected using a current sensor or the like attached to the electric motor 1.

  Next, based on the rotational speed of the electric motor 1, it is determined whether or not it is necessary to switch the coil 3 from the delta connection to the Y connection. That is, it is determined whether the connection state of the coil 3 is a delta connection and the rotation speed of the electric motor 1 is equal to or less than a threshold value (reference value of the rotation speed) (step S302).

  In the case of heating operation, the threshold value used in step S302 is preferably a value (more preferably an intermediate value) between the rotation speed N1 corresponding to the heating intermediate condition and the rotation speed N2 corresponding to the heating rated condition. In the case of the cooling operation, the threshold used in step S302 is a value (more preferably an intermediate value) between the rotation speed N1 corresponding to the cooling intermediate condition and the rotation speed N2 corresponding to the cooling rated condition. desirable.

  For example, in the case of a domestic air conditioner having a refrigeration capacity of 6.3 kW, the rotation speed N1 corresponding to the heating intermediate condition is 35 rps, and the rotation speed N2 corresponding to the heating rated condition is 85 rps. Is preferably 60 rps, which is an intermediate value between the rotational speed N1 and the rotational speed N2.

  However, the rotation speed of the electric motor 1 may fluctuate. Therefore, in this step S302, it is determined whether or not the state where the rotational speed of the electric motor 1 is equal to or greater than the threshold value continues for a preset time.

  As a result of the comparison in step S302, if the connection state of the coil 3 is delta connection and the rotation speed of the electric motor 1 is equal to or less than the threshold value, the processing of steps S121 to S124 shown in FIG. 11 is performed. In steps S121 to S124 in FIG. 11, as described in the first embodiment, switching from delta connection to Y connection and boosting of the bus voltage of converter 102 are performed.

  As a result of the comparison in step S302, when the connection state of the coil 3 is not delta connection (when it is Y connection), or when the rotation speed of the motor 1 is larger than the threshold value (that is, when it is not necessary to switch to Y connection). In step S303, the process proceeds to step S303.

  In step S303, it is determined whether or not switching from the Y connection to the delta connection is necessary. That is, it is determined whether or not the connection state of the coil 3 is the Y connection and the rotation speed of the electric motor 1 is greater than the threshold value.

  As a result of the comparison in step S303, if the connection state of the coil 3 is Y-connection and the rotation speed of the electric motor 1 is larger than the threshold value, the processing of steps S131 to S134 shown in FIG. 12 is performed. In steps S131 to S134 in FIG. 12, as described in the first embodiment, switching from the Y connection to the delta connection and the reduction of the bus voltage of the converter 102 are performed.

  As a result of the comparison in step S303, when the connection state of the coil 3 is not the Y connection (when it is a delta connection), or when the rotation speed of the electric motor 1 is larger than the threshold (that is, when it is not necessary to switch to the delta connection). Returns to step S105. The processing (steps S109 to S111) when the operation stop signal is received is the same as that in the first embodiment. Other operations and configurations in the fifth modification are the same as those in the first embodiment.

  Thus, in the fifth modification, high motor efficiency and high motor torque can be obtained by switching the connection state of the coil 3 and the bus voltage of the converter 102 based on the rotation speed of the motor 1.

  In the first modification, the second modification, and the third modification, the connection state of the coil 3 and the bus voltage of the converter 102 may be switched based on the rotation speed of the electric motor 1.

  Here, the rotary compressor 8 has been described as an example of the compressor, but the electric motor of each embodiment may be applied to a compressor other than the rotary compressor 8.

Embodiment 2. FIG.
Next, a second embodiment of the present invention will be described.

<Configuration of air conditioner>
FIG. 37 is a block diagram showing a configuration of an air conditioning system 600 having the air conditioner 500 of the second embodiment. FIG. 38 is a block diagram showing the configuration of the air conditioner 500 according to the second embodiment. FIG. 39 is a block diagram illustrating a control system of air conditioner 500 according to the second embodiment. FIG. 40 is a block diagram illustrating a control system of drive device 100a according to the second embodiment.

  In Embodiment 2, the air conditioning system 600 includes an air conditioner 500 and a communication device 501. The air conditioner 500 of Embodiment 2 further includes a compressor temperature sensor 71 as a compressor state detection unit (FIG. 39). The compressor temperature sensor 71 is a temperature sensor that detects a compressor temperature indicating the state of the rotary compressor 8. However, the compressor state detection part should just be a detector which can detect the state of the rotary compressor 8, and is not restricted to a temperature sensor.

  In the example shown in FIG. 40, the drive device 100 a switches the converter 102 that generates the bus voltage applied to the coil 3, the inverter 103 that outputs an AC voltage to the coil 3 of the electric motor 1, and the connection state of the coil 3. The connection switching part 60, the control apparatus 50, and the compressor temperature sensor 71 are comprised. Power is supplied to the converter 102 from a power source 101 which is an alternating current (AC) power source.

  Except for the compressor temperature sensor 71, the configuration of the drive device 100a of the second embodiment is the same as the configuration of the drive device 100 of the first embodiment. However, the compressor temperature sensor 71 may not be a component of the drive device 100a. The driving device 100 a is used together with the rotary compressor 8 and drives the electric motor 1.

FIG. 41 is a diagram illustrating a configuration of the communication device 501.
The communication device 501 is a remote controller (for example, the remote controller 55 described in Embodiment 1), a personal computer, a server computer, or a smartphone. The communication device 501 includes an input device 501a for inputting an operation mode (hereinafter also simply referred to as “operation mode”) of the air conditioner 500, and a display 501b for displaying the operation mode.

  The communication device 501 can communicate with the air conditioner 500 by wireless communication or wired communication. The communication device 501 transmits an operation mode signal as a control signal for controlling the operation mode of the air conditioner 500 to the air conditioner 500.

  The input device 501a is an input interface such as a button, a touch panel, or a keyboard. The user can input the operation mode and the set temperature to the air conditioner 500 using the input device 501a. Information (for example, operation mode or set temperature) input to the communication device 501 by the user is transmitted to the air conditioner 500 (specifically, the signal receiving unit 56) as a control signal. The signal receiver 56 of the air conditioner 500 receives a control signal (for example, an operation mode signal indicating an operation mode or a set temperature signal indicating a set temperature) transmitted from the communication device 501.

  Information (for example, operation mode) input by the user is displayed on the display 501b. Further, when the communication device 501 receives the current operation mode of the air conditioner 500 from the air conditioner 500, the current operation mode of the air conditioner 500 is displayed on the display 501b. The indicator 501b may include a lamp such as an LED (light emitting diode) for informing the operation mode. The air conditioner 500 may be provided with a display device having the same function as the display device 501b.

  The control signal transmitted from the communication device 501 may not be input directly to the air conditioner 500. For example, the user may transmit the operation mode to the air conditioner 500 using cloud computing. In this case, the control signal transmitted from the communication device 501 is transmitted to the air conditioner 500 via a computer that is communicably connected to the communication device 501.

  The operation mode signal input to the signal receiving unit 56 is transferred to the control device 50. In the present embodiment, the operation mode signal input to the signal receiving unit 56 is input to the indoor control device 50a. Further, a signal based on the operation mode signal transferred from the signal receiving unit 56 is transferred from the indoor control device 50a to the outdoor control device 50b. The signal transferred from the indoor control device 50a may be the same signal as the operation mode signal, or may be a signal converted based on the operation mode signal.

  The control device 50 receives the operation mode signal from the signal receiving unit 56 and controls the operation mode of the air conditioner 500 based on the operation mode signal. Specifically, the control apparatus 50 controls the connection state of the coil 3 according to the operation mode designated by the user. That is, the control device 50 controls the operation mode by controlling the connection switching unit 60 based on the operation mode signal. It is desirable that the control device 50 controls the connection switching unit 60 so as to maintain the connection state of the coil 3 until the operation mode is changed. Thereby, the control for switching the connection can be simplified, and the number of times of switching the connection can be reduced.

  The connection switching unit 60 switches the connection state of the coil 3 between the Y connection (first connection state) and the delta connection (second connection state) according to the control of the control device 50. In the delta connection, the line voltage of the coil 3 is lower than that of the Y connection.

  When the connection state of the coil 3 is a Y connection, the efficiency of the low speed rotation of the electric motor 1 can be increased. On the other hand, when the connection state of the coil 3 is a delta connection, the efficiency of high-speed rotation of the electric motor 1 can be increased. The maximum output of the electric motor 1 when the connection state of the coil 3 is a delta connection is larger than the maximum output of the electric motor 1 when the connection state of the coil 3 is a Y connection.

  Further, control device 50 controls the operation mode by controlling converter 102 based on the operation mode signal. In the present embodiment, control device 50 controls converter 102 so that the bus voltage is maintained constant until the operation mode is changed. Thereby, the control of the bus voltage can be simplified.

  As the number of revolutions of the electric motor 1 increases, the induced voltage generated in the coil 3 increases, and thereby the bus voltage becomes insufficient. Therefore, as described in the first embodiment, when the rotation speed of electric motor 1 reaches a preset rotation speed, control device 50 controls inverter 103, and inverter 103 starts field weakening control. In field weakening control, control device 50 controls converter 102 so that the bus voltage is boosted. Thereby, the efficiency of the electric motor 1 can be improved.

  On the other hand, when motor 1 is rotating at a low speed, control device 50 controls converter 102 so that the bus voltage is not boosted. Thereby, the energy loss accompanying boosting of the bus voltage can be avoided, and the efficiency of the electric motor 1 can be improved.

  The optimum bus voltage depends on the rotational speed of the electric motor 1 and the connection state of the coil 3. As described above, the effect of improving the efficiency of the electric motor 1 by increasing the bus voltage increases as the rotational speed of the electric motor 1 increases. However, when the rotation speed of the motor 1 in the Y connection is the same as the rotation speed of the motor 1 in the delta connection, the delta connection reduces the induced voltage in the coil 3 and increases the margin of the bus voltage compared to the Y connection. Improve. Therefore, when the connection state of the coil 3 is a delta connection, the necessity for boosting the bus voltage is small. That is, since the optimal bus voltage changes according to the combination of the rotation speed and the connection state of the electric motor 1, the control device 50 controls the bus voltage according to the rotation speed and the connection state of the electric motor 1.

  When the motor 1 is started, it is desirable that the connection state of the coil 3 is a delta connection. For example, so that the connection state of the coil 3 is a delta connection from when the operation mode signal indicating power-on for starting the operation of the air conditioner is input to the control device 50 until the motor 1 starts driving, The control device 50 controls the connection switching unit 60. After the electric motor 1 starts driving, the control device 50 controls the connection state of the coil 3 according to the operation mode.

  Switching of the operation mode may be performed after elapse of a predetermined time from when the user inputs the operation mode by using the timer reservation function. Furthermore, a control program for automatically determining the switching timing of the operation mode based on various personal data such as the user's use history of the air conditioner 500, the user's preference, or the power consumption data regardless of the direct instruction of the user. In use, the operation mode may be switched. In particular, when a control signal is transmitted to the air conditioner 500 by cloud computing, various personal data can be stored in the server, and operation mode switching timing can be determined using the various personal data stored in the server. Arithmetic can be performed.

  When using cloud computing, a sufficient data storage capacity and calculation processing speed can be obtained, which is suitable for a configuration for automatically switching operation modes. However, various personal data may be stored in the control device 50, and a calculation unit provided in the control device 50 may calculate the automatic switching timing of the operation mode.

  The control device 50 selects an appropriate connection state based on the table data indicating the correspondence relationship between the operation mode and the connection state, and controls the connection switching unit 60. Table data indicating the correspondence between the operation mode and the bus voltage is stored in the memory 58 in advance. The boost of the bus voltage for each operation mode is determined based on the load and connection state of the electric motor 1 assumed in the operation mode.

  Furthermore, the control device 50 may control the connection state and the bus voltage of the coil 3 based on the room temperature detected by the room temperature sensor 54 and the set temperature. For example, when the difference between the room temperature and the set temperature is 3 ° C. or more, the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is a delta connection, and the bus output from the converter 102 The converter 102 is controlled so that the voltage is boosted. As a result, a high-load operation can be performed in order to follow a sudden change in the set temperature.

  The air conditioner 500 has a plurality of operation modes. In the present embodiment, as the first operation mode, “cooling mode (hereinafter also referred to as cooling)”, “weak cooling and dehumidification mode (hereinafter also referred to as weak cooling and dehumidification)”, and “air blowing mode (hereinafter also referred to as air blowing). ) ”,“ Weak operation mode (hereinafter also referred to as weak operation) ”, and“ power saving mode (hereinafter also referred to as power saving) ”. As the second operation mode, “heating mode (hereinafter also referred to as heating)”, “reheat dehumidification mode (hereinafter also referred to as reheat dehumidification)”, “clothing drying mode (hereinafter also referred to as clothing drying)”, and The “strong driving mode (hereinafter also referred to as strong driving)” is used.

Next, an example of the operation in each operation mode in the air conditioner 500 will be described.
In the present embodiment, the air conditioner 500 is for 4.0 kw. When the connection state of the coil 3 is a delta connection, the rated rotational speed of the electric motor 1 is 60 rps. When the converter 102 boosts, the bus voltage increases up to 1.5 times.

  In the first operation mode, since the load of the electric motor 1 is smaller than that in the second operation mode, the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is the Y connection. On the other hand, in the second operation mode, since the load of the electric motor 1 is larger than that in the first operation mode, the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is a delta connection. To do. In particular, “strong operation” is an operation mode that is assumed to be used in a situation where the room temperature fluctuates severely. Therefore, in the “strong operation”, it is desirable that the connection state of the coil 3 is a delta connection excellent in the maximum output of the electric motor 1.

  The cooling mode is an operation mode for the purpose of lowering the room temperature. In the cooling mode, the air conditioner 500 is operated in a state where the outside air temperature is higher than the target room temperature, the heat exchanger on the outdoor unit 5B side becomes relatively high by heat exchange via the refrigerant, and the heat on the indoor unit 5A side The exchanger becomes relatively cold. By blowing air through the heat exchanger on the indoor unit 5A side that has become low temperature, cold air is sent into the room.

  The weak cooling and dehumidifying mode is an operation mode for the purpose of reducing indoor humidity. In the weak cooling and dehumidifying mode, dehumidification is performed using a cooling refrigeration cycle. Specifically, the outside air is cooled in the heat exchanger on the indoor unit 5A side, a part of the water vapor contained in the outside air is condensed, and moisture adheres to the surface of the heat exchanger. After the moisture adhering to the surface of the heat exchanger is removed, the indoor humidity can be lowered by sending the outside air with a reduced amount of moisture into the room. Generally, the temperature of the user's sensation decreases as the humidity decreases. In the weak cooling and dehumidifying mode, it is necessary to suppress the dehumidifying operation to such an extent that the user's sensible temperature does not decrease too much, so the load on the electric motor 1 is smaller than in the cooling mode.

  The air blowing mode is an operation mode in which air is blown in the air conditioner 500 without using a refrigeration cycle, or air is blown using a refrigeration cycle slightly. Since the load of the refrigeration cycle is small, the load of the electric motor 1 is small compared to other operation modes. In the air blowing mode, when the air is blown without using the refrigeration cycle, the connection state of the coil 3 may not be switched. When the refrigeration cycle is not used, the electric motor 1 in the compressor 41 is not driven, so that the connection state of the coil 3 does not affect the operation characteristics of the air conditioner 500.

  The weak operation mode is an operation mode in which cooling operation or heating operation is performed. However, as compared with the cooling mode and the heating mode, the heat exchange amount of the refrigeration cycle is reduced, and the air flow rate is reduced. Thereby, an air-conditioning capability (cooling intensity | strength or heating intensity | strength) falls and electric power consumption is suppressed. Since the load of the refrigeration cycle is small, the load of the electric motor 1 is small compared to the cooling mode and the heating mode.

  The power saving mode is an operation mode in which cooling operation or heating operation is performed. Specifically, the power saving mode automatically adjusts the operation load of the air conditioner 500 (including the operation load of the electric motor 1) so that the efficiency of the air conditioner 500 is maximized, thereby reducing power consumption over the long term. This is an operation mode to be reduced. In the power saving mode, since the operation is continuously performed with a small load for a long time, the load on the electric motor 1 is small compared to the cooling mode and the heating mode.

  The heating mode is an operation mode for the purpose of raising the room temperature. In the heating mode, the air conditioner 500 is operated in a state where the outside air temperature is lower than the target room temperature, the heat exchanger on the outdoor unit 5B side becomes relatively low temperature by heat exchange via the refrigerant, and the heat on the indoor unit 5A side The exchanger becomes relatively hot. By blowing air through the heat exchanger on the indoor unit 5A side that has become high temperature, warm air is sent into the room. In the heating operation, frost is generated on the surface of the heat exchanger on the low temperature side (for example, the heat exchanger on the outdoor unit 5B side), and the surface area effective for heat exchange is reduced. Thereby, the efficiency of a heat exchanger falls and the work of the required rotary compressor 8 increases. In addition, in order to remove the generated frost, the defrosting operation is periodically performed. However, since the work of the rotary compressor 8 at the time of the defrosting operation does not contribute to the air conditioning capacity, the total amount of work of the rotary compressor 8 is Further increase. Therefore, the heating mode is an operation mode with a higher load than the cooling mode, and the load on the electric motor 1 is larger in the heating mode than in the cooling mode.

  The reheat dehumidification mode is an operation mode for reducing the humidity in the room. The difference from the weak cooling and dehumidifying mode is that in the reheating and dehumidifying mode, the air taken into the air conditioner is cooled and dehumidified, then heated again and then released into the room, thereby suppressing a decrease in room temperature. In the reheat dehumidification mode, energy loss occurs due to reheating after dehumidification. Furthermore, in the reheat dehumidification mode, there is no operation restriction due to a decrease in room temperature accompanying dehumidification, unlike the weak cooling dehumidification mode. Therefore, the load of the electric motor 1 is large.

  The clothes drying mode is an operation mode for the purpose of drying clothes. The operation principle is the same as in the reheat dehumidification mode. However, since the clothes are dried, the dehumidifying amount, the blowing temperature, and the blowing amount can be adjusted. Compared to the reheat dehumidification mode, the air flow rate is set large in order to promote heat exchange between the clothing and the air. Similar to the reheat dehumidification mode, energy loss occurs due to reheating after dehumidification, and there is no operation restriction due to a decrease in room temperature due to dehumidification as in the weak cooling dehumidification mode. Therefore, the load of the electric motor 1 is large.

  The strong operation mode is an operation mode in which cooling operation or heating operation is performed. In the strong operation mode, air conditioning is performed at the maximum capacity. Compared with the cooling mode and the heating mode, the air exchange capacity is increased by increasing the heat exchange amount in the refrigeration cycle and increasing the air flow rate. Since the load of the refrigeration cycle is increased, the load on the electric motor 1 is larger than that in the cooling mode and the heating mode.

  As described above, in the first operation mode, which is the cooling mode, the weak cooling / dehumidifying mode, the air blowing mode, the weak operation mode, and the power saving mode, the load of the motor 1 is low. The connection switching unit 60 is controlled so that the state is the Y connection. In contrast, in the second operation mode, which is the heating mode, the reheat dehumidification mode, the clothes drying mode, and the strong operation mode, the load of the electric motor 1 is high. The connection switching part 60 is controlled so that it is a connection.

Next, an example of the control method of the air conditioner 500 will be described.
FIG. 42 is a flowchart illustrating an example of the operation of the control device 50.

  In step S <b> 201, the control device 50 is waiting for an operation mode signal from the communication device 501.

  When the control device 50 receives the operation mode signal (step S202), the control device 50 controls the connection state of the coil 3 based on the operation mode signal (step S203 to step S205).

  In step S203, the control device 50 determines whether to switch the connection state of the coil 3 based on the operation mode signal. In other words, the control device 50 determines whether to switch the connection state of the coil 3 according to the operation mode.

  When control device 50 switches the connection state (Yes in step S203), control device 50 controls inverter 103 so that electric motor 1 stops. Thereby, the electric motor 1 stops (step S204).

  After the electric motor 1 stops, the control device 50 switches the connection state (step S205).

  When switching of the connection state is not necessary (No in step S203), the control device 50 controls the connection switching unit 60 so that the connection state is maintained.

  In step S206, control device 50 determines whether to boost the bus voltage based on the operation mode signal. In other words, the control device 50 determines whether to boost the bus voltage according to the operation mode.

  When boosting the bus voltage (Yes in step S206), control device 50 controls converter 102 so that the bus voltage is boosted (step S207).

  When the bus voltage is not increased (No in step S206), control device 50 controls converter 102 so that the bus voltage is maintained constant. Also when boosting the bus voltage, after boosting, control device 50 may control converter 102 so that the bus voltage is maintained constant.

  In step S208, the control device 50 determines whether the electric motor 1 is stopped.

  When electric motor 1 is stopped (Yes in step S208), control device 50 controls inverter 103 so that electric motor 1 is driven (step S209). Thereby, the electric motor 1 starts.

  When electric motor 1 is not stopped (No in step S208), the process returns to step S201.

  Each operation mode is associated in advance with the maximum rotational speed Nm of the electric motor 1. Maximum rotation speed Nm is determined according to the load of electric motor 1 assumed in each operation mode. The control device 50 determines the connection switching unit 60 (specifically, the connection state of the coil 3) and the converter 102 (specifically, the bus voltage) based on the relationship between the maximum rotation speed Nm and a predetermined threshold value. Control. The threshold value of the rotation speed of the electric motor 1 is common between the respective operation modes.

  When the maximum rotation speed Nm is smaller than a predetermined threshold value D1 (first threshold value), the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is the Y connection, and from the converter 102 Converter 102 is controlled such that the output bus voltage is maintained constant. The threshold value D1 is the rotation speed of the electric motor 1 when the line voltage reaches the maximum output voltage from the inverter 103 in a state where the connection state of the coil 3 is Y connection and the bus voltage is maintained constant. In the present embodiment, the threshold value D1 is 34 rps. When the maximum rotational speed Nm is smaller than the threshold value D1, the maximum output voltage from the inverter 103 is sufficient with respect to the line voltage, so that it is not necessary to boost the bus voltage.

  When the maximum rotation speed Nm is larger than the threshold D1 and smaller than a predetermined threshold D2 (second threshold), the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is the Y connection. Then, the converter 102 is controlled so that the bus voltage output from the converter 102 is boosted. The threshold value D2 is when the line voltage reaches the maximum output voltage from the inverter 103 in a state where the connection state of the coil 3 is Y connection and the bus voltage is boosted to the maximum voltage (predetermined maximum value). This is the rotational speed of the electric motor 1. In the present embodiment, the threshold value D2 is 50 rps.

  When the bus voltage is not boosted under the condition of D1 <Nm <D2, the inverter maximum output voltage is insufficient with respect to the line voltage. Therefore, control device 50 starts field weakening control. If the rotational speed exceeds the rotational speed (starting rotational speed) when the field-weakening control operation is started, the motor current may increase and the efficiency of the motor 1 may be reduced. Therefore, under the condition of D1 <Nm <D2, the controller 50 controls the converter 102 so that the bus voltage is boosted, so that a sufficient maximum output voltage is supplied from the inverter 103 to the electric motor 1. Thereby, the increase in the motor current by the field weakening control and the decrease in the efficiency of the motor 1 can be suppressed.

  When the maximum rotation speed Nm is larger than the threshold value D2 and smaller than a predetermined threshold value D3 (third threshold value), the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is a delta connection. Then, the converter 102 is controlled so that the bus voltage output from the converter 102 is kept constant. The threshold value D3 is the number of revolutions of the electric motor 1 when the line voltage reaches the maximum output voltage from the inverter 103 when the connection state of the coil 3 is a delta connection and the bus voltage is maintained constant. In the present embodiment, the threshold value D3 is 60 rps.

  Under the condition of D2 <Nm <D3, when the connection state of the coil 3 is Y connection, the maximum output voltage from the inverter 103 is insufficient, and field weakening control is started. Therefore, the control device 50 controls the connection switching unit 60 so that the connection state of the coil 3 is a delta connection. When the connection state of the coil 3 is a delta connection under the condition of D2 <Nm <D3, the maximum output voltage sufficient for the line voltage is supplied from the inverter 103 to the electric motor 1, so that the bus voltage needs to be boosted. There is no.

  When maximum rotational speed Nm is larger than threshold value D3, control device 50 controls connection switching unit 60 so that the connection state of coil 3 is a delta connection, so that the bus voltage output from converter 102 is boosted. The converter 102 is controlled.

  When the bus voltage is not boosted under the condition of D3 <Nm, the inverter maximum output voltage is insufficient with respect to the line voltage. Therefore, control device 50 starts field weakening control. Therefore, under the condition of D3 <Nm, the control device 50 controls the converter 102 so that the bus voltage is boosted, so that a sufficient maximum output voltage is supplied from the inverter 103 to the electric motor 1. Thereby, the increase in the motor current by the field weakening control and the decrease in the efficiency of the motor 1 can be suppressed.

  In the weak cooling and dehumidifying mode, the air blowing mode, the weak operation mode, and the power saving mode, the maximum rotation speed Nm of the electric motor 1 is, for example, 0 to 30 rps, and the load of the electric motor 1 is small. Therefore, in these operation modes, control device 50 controls connection switching unit 60 so that the connection state of coil 3 is the Y connection, and the converter 50 maintains the bus voltage output from converter 102 constant. 102 is controlled. That is, converter 102 does not boost the bus voltage.

  In the reheat dehumidification mode, the clothes drying mode, and the strong operation mode, the maximum rotation speed Nm of the electric motor 1 is, for example, 60 rps to 100 rps, and the load on the electric motor 1 is large. Therefore, in these operation modes, control device 50 controls connection switching unit 60 so that the connection state of coil 3 is a delta connection, and controls converter 102 so that the bus voltage output from converter 102 is boosted. Control.

  In the cooling mode and the heating mode, the range of the maximum rotation speed Nm is wide as compared with other operation modes. For example, in the cooling mode, the maximum rotational speed Nm of the electric motor 1 is 10 rps to 60 rps. In the cooling mode, the operation load is relatively small compared to the heating mode, and the time of low-speed operation at 30 rps or less occupies most of the operation time. Therefore, in the cooling mode, control device 50 controls connection switching unit 60 so that the connection state of coil 3 is the Y connection, and controls converter 102 so that the bus voltage output from converter 102 is maintained constant. Control. Even when field weakening control is started, the rotational speed can be increased to 60 rps without increasing the bus voltage.

  In the heating mode, the maximum rotation speed Nm of the electric motor 1 is, for example, 20 rps to 100 rps. In the heating mode, the operation load is relatively large compared to the cooling mode, and it is desirable to maintain the maximum heating capacity in a cold region. Therefore, in the heating mode, control device 50 controls connection switching unit 60 so that the connection state of coil 3 is a delta connection, and controls converter 102 so that the bus voltage output from converter 102 is boosted. .

Next, another example of the control method of the air conditioner 500 will be described.
43 and 44 are flowcharts illustrating another example of the operation of the control device 50.

  In step S <b> 301, the control device 50 is waiting for an operation mode signal from the communication device 501.

  When control device 50 receives the operation mode signal (step S302), control device 50 sets maximum rotation speed Nm based on the operation mode signal, and controls the bus voltage and the connection state of coil 3. These operations will be specifically described below.

  In step S401, the control device 50 sets the maximum rotation speed Nm based on the operation mode signal.

  In step S402, the control device 50 determines whether the maximum rotation speed Nm set in step S401 is smaller than the threshold value D2.

  When maximum rotation speed Nm is smaller than threshold value D2 (Yes in step S402), control device 50 determines whether maximum rotation speed Nm is smaller than threshold value D1 (step S403).

  When maximum rotation speed Nm is smaller than threshold value D1 (Yes in step S403), control device 50 determines the connection state and bus voltage control method. Specifically, control device 50 selects Y connection as the connection state, and selects non-boosting of bus voltage (step S404).

  When maximum rotation speed Nm is greater than threshold value D1 (No in step S403), control device 50 determines a connection state control method. Specifically, the control device 50 selects the Y connection as the connection state (step S405). In step S405, it is desirable to boost the bus voltage.

  When maximum rotation speed Nm is larger than threshold value D2 (No in step S402), control device 50 determines whether maximum rotation speed Nm is larger than threshold value D3 (step S406).

  When maximum rotation speed Nm is larger than threshold value D3 (Yes in step S406), control device 50 determines a connection state and a bus voltage control method. Specifically, control device 50 selects delta connection as the connection state, and selects boosting of bus voltage (step S407).

  When maximum rotation speed Nm is smaller than threshold value D3 (No in step S406), control device 50 determines a connection state and a bus voltage control method. Specifically, control device 50 selects delta connection as the connection state, and selects non-boosting of bus voltage (step S408).

  In step S303, the control device 50 determines whether to switch the connection state of the coil 3 based on the operation mode signal. In other words, the control device 50 determines whether to switch the connection state of the coil 3 according to the processing results from step S401 to step S408.

  When control device 50 switches the connection state (Yes in step S303), control device 50 controls inverter 103 so that electric motor 1 stops. Thereby, the electric motor 1 stops (step S304).

  After the electric motor 1 stops, the control device 50 switches the connection state (step S305).

  When it is not necessary to switch the connection state (No in step S303), the control device 50 controls the connection switching unit 60 so that the connection state is maintained.

  In step S306, control device 50 determines whether to increase the bus voltage according to the results of the processing from step S401 to step S408.

  When boosting the bus voltage (Yes in step S306), control device 50 controls converter 102 so that the bus voltage is boosted (step S307).

  When the bus voltage is not increased (No in step S306), control device 50 controls converter 102 so that the bus voltage is maintained constant.

  In step S308, the control device 50 determines whether the electric motor 1 is stopped.

  When the electric motor 1 is stopped (Yes in Step S308), the control device 50 controls the inverter 103 so that the electric motor 1 is driven (Step S309). Thereby, the electric motor 1 starts.

  When electric motor 1 is not stopped (No in step S308), the process returns to step S301.

  As described above, according to the second embodiment, the connection state of the coil 3 can be appropriately controlled according to the operation mode of the air conditioner 500. Thereby, since the connection state of the coil 3 is set to an optimal state according to the operation mode of the air conditioner 500, air conditioning comfortable for the user can be performed.

  The features in each embodiment and each modification described above can be appropriately combined with each other.

  The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the above-described embodiments, and various improvements or modifications are made without departing from the scope of the present invention. be able to.

  DESCRIPTION OF SYMBOLS 1 Electric motor, 3, 3U, 3V, 3W coil, 5,500 Air conditioner, 5A indoor unit, 5B Outdoor unit, 8 Rotary compressor (compressor), 9 Compression mechanism, 10 Stator, 11 Stator core, 12 Teeth part, 20 rotor, 21 rotor core, 25 permanent magnet, 41 compressor, 42 four-way valve, 43 outdoor heat exchanger, 44 expansion valve, 45 indoor heat exchanger, 46 outdoor blower fan, 47 indoor blower fan, 50 control device, 50a indoor Control device, 50b outdoor control device, 50c communication cable, 51 input circuit, 52 arithmetic circuit, 53 output circuit, 54 indoor temperature sensor, 55 remote control, 56 signal receiving unit, 57 CPU, 58 memory, 60 connection switching unit, 61, 62, 63 switch, 71 compressor Degree sensor, 80 shell, 81 a glass terminal, 85 discharge pipe, 90 a shaft, 100, 100a drives, 101 power supply, 102 converter, 103 inverter, 501 communication device, 600 an air conditioning system.

An air conditioner according to the present invention is an air conditioner including an electric motor having a coil, wherein the converter generates a bus voltage applied to the coil, the connection state of the coil, the first connection state, and the A connection switching unit that switches between a second connection state that lowers the line voltage of the coil from the first connection state, and a signal reception that receives an operation mode signal for controlling the operation mode of the air conditioner And a control device that receives the operation mode signal from the signal reception unit and controls the operation mode based on the operation mode signal, the control device switching the connection based on the operation mode signal The operation mode is controlled by controlling the unit, and the connection switching unit is controlled so as to maintain the connection state of the coil until the operation mode is changed .

Claims (25)

An air conditioner including an electric motor having a coil,
A converter that generates a bus voltage applied to the coil;
A connection switching unit that switches a connection state of the coil between a first connection state and a second connection state in which a line voltage of the coil is lower than the first connection state;
A signal receiving unit for receiving an operation mode signal for controlling an operation mode of the air conditioner;
An air conditioner comprising: a control device that receives the operation mode signal from the signal receiving unit and controls the operation mode based on the operation mode signal.   The air conditioner according to claim 1, wherein the control device controls the operation mode by controlling the connection switching unit based on the operation mode signal.   The air conditioner according to claim 1 or 2, wherein the control device controls the operation mode by controlling the converter based on the operation mode signal.   The air conditioner according to any one of claims 1 to 3, wherein the control device controls the converter so that the bus voltage is kept constant until the operation mode is changed. The coil is a three-phase coil;
5. The first connection state is a state in which the three-phase coil is connected by Y connection, and the second connection state is a state in which the three-phase coil is connected by delta connection. The air conditioner according to any one of the above. The coil is a three-phase coil connected by Y connection or delta connection,
The first connection state is a state in which the three-phase coils are connected in series for each phase,
The air conditioner according to any one of claims 1 to 4, wherein the second connection state is a state in which the three-phase coils are connected in parallel for each phase.   When the operation mode is the weak cooling / dehumidification mode, the control device controls the connection switching unit so that the connection state of the coil is the first connection state, and the bus voltage is maintained constant. The air conditioner according to any one of claims 1 to 6, wherein the converter is controlled as described above.   When the operation mode is the air blowing mode, the control device controls the connection switching unit so that the connection state of the coil is the first connection state, so that the bus voltage is maintained constant. The air conditioner of any one of Claim 1 to 6 which controls the said converter.   When the operation mode is the weak operation mode, the control device controls the connection switching unit so that the connection state of the coil is the first connection state, so that the bus voltage is maintained constant. The air conditioner according to any one of claims 1 to 6, wherein the converter is controlled.   When the operation mode is the power saving mode, the control device controls the connection switching unit so that the connection state of the coil is the first connection state, so that the bus voltage is maintained constant. The air conditioner of any one of Claim 1 to 6 which controls the said converter.   When the operation mode is the reheat dehumidification mode, the control device controls the connection switching unit so that the connection state of the coil is the second connection state, so that the bus voltage is boosted. The air conditioner of any one of Claim 1 to 6 which controls the said converter.   When the operation mode is the clothes drying mode, the control device controls the connection switching unit so that the connection state of the coil is the second connection state, so that the bus voltage is increased. The air conditioner of any one of Claim 1 to 6 which controls a converter.   When the operation mode is the strong operation mode, the control device controls the connection switching unit so that the connection state of the coil is the second connection state, and the bus voltage is boosted. The air conditioner of any one of Claim 1 to 6 which controls a converter. A temperature sensor for detecting the room temperature;
The signal receiving unit receives a set temperature signal indicating a set temperature of the air conditioner,
When the difference between the room temperature detected by the temperature sensor and the set temperature is 3 ° C. or more,
The control device controls the connection switching unit so that a connection state of the coil is the second connection state, and controls the converter so that a bus voltage output from the converter is boosted. The air conditioner according to any one of 1 to 6.   15. The control device according to claim 1, wherein the control device controls the connection switching unit and the converter based on a maximum rotational speed of the electric motor associated with the operation mode and a predetermined threshold value. Air conditioner.   The control device controls the connection switching unit so that the connection state of the coil is the first connection state when the maximum rotational speed is smaller than a predetermined first threshold. The air conditioner described.   When the maximum rotation speed is larger than the first threshold and smaller than a predetermined second threshold, the control device causes the connection so that the connection state of the coil is the first connection state. The air conditioner according to claim 15 or 16, wherein the converter is controlled so as to control a switching unit so that the bus voltage is boosted.   When the maximum rotational speed is larger than the second threshold and smaller than a predetermined third threshold, the control device causes the connection so that the connection state of the coil is the second connection state. The air conditioner according to any one of claims 15 to 17, which controls the switching unit.   When the maximum rotational speed is greater than the third threshold, the control device controls the connection switching unit so that the connection state of the coil is the second connection state, and the bus voltage is boosted. The air conditioner according to claim 18, wherein the converter is controlled such that the air conditioner is controlled. An air conditioner,
A communication device that transmits an operation mode signal for controlling an operation mode of the air conditioner to the air conditioner;
The air conditioner
An electric motor having a coil;
A converter that generates a bus voltage applied to the coil;
A connection switching unit that switches a connection state of the coil between a first connection state and a second connection state in which a line voltage of the coil is lower than the first connection state;
A signal receiving unit for receiving an operation mode signal for controlling an operation mode of the air conditioner;
An air conditioning system comprising: a control device that receives the operation mode signal from the signal reception unit and controls the operation mode based on the operation mode signal.   The air conditioning system according to claim 20, wherein the communication device is a remote controller, a personal computer, a server computer, or a smartphone.   The air conditioning system according to claim 20 or 21, wherein the communication device has an input device for inputting the operation mode.   The air conditioning system according to any one of claims 20 to 22, wherein the communication device includes a display for displaying the operation mode. A method for controlling an air conditioner including an electric motor having a coil,
Receiving an operation mode signal for controlling an operation mode of the air conditioner;
Controlling the connection state of the coil based on the operation mode signal.   The method of controlling an air conditioner according to claim 24, further comprising a step of controlling a bus voltage applied to the coil based on the operation mode signal.

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