JPWO2020059095A1 - Motor drive and refrigeration cycle equipment - Google Patents

Abstract

When switching from the open winding mode to the star connection mode, the motor controller turns on the switching of the open winding mode before switching, and if the off-duty (or voltage utilization rate) exceeds the set value, turns it on. The off-duty (or voltage utilization rate) is reduced to the set value or less, and after this reduction, switching from the open winding mode to the star-shaped connection mode is executed.

Description

The present invention relates to a motor drive device and a refrigeration cycle device for driving a permanent magnet synchronous motor, a so-called open winding motor, which has a plurality of phase windings that are not connected to each other.

A permanent magnet synchronous motor having a plurality of phase windings is used as a driving motor for a compressor mounted on a refrigeration cycle device such as an air conditioner or a heat source machine. Further, as an example of a permanent magnet synchronous motor, an open winding motor (Open-Windings Motor) having a configuration in which a plurality of phase windings are not connected to each other is known.

The motor drive device that drives this open winding motor (abbreviated as a motor) energizes the first inverter that controls energization of one end of each phase winding of the motor and the other end of each phase winding of the motor. It is equipped with a second inverter to control and a switch connected between the other ends of each phase winding, and by closing this switch, each phase winding is connected in a star shape and only the first inverter is switched independently. Selectively set the star-shaped connection mode and the open winding mode in which each phase winding is disconnected (open state) by opening the switch and the first inverter and the second inverter are switched in cooperation with each other. ..

In the open winding mode, a high level voltage that is about twice as high as in the star connection mode can be applied to each phase winding, so the motor speed is in the low speed operation range (low / medium speed operation) below the threshold value. In the region), the star-shaped connection mode is set, and the on / off duty of the independent switching of the first inverter is controlled so that the speed of the motor becomes the target speed. In the high speed operation range where the speed of the motor is equal to or higher than the threshold value, the open winding mode is set, and the on / off duty of the cooperative switching of the first inverter and the second inverter is controlled so that the speed of the motor becomes the target speed. By switching in this way, it is possible to operate at a high speed, and high efficiency can be obtained in a wide operating speed range.

When switching from the star connection mode to the open winding mode while continuing the operation without stopping the motor, the motor drive device turns on 1/2 of the star connection mode in the open winding mode after switching. Set off duty. On the contrary, when switching from the open winding mode to the star connection mode, the on / off duty is set twice as much as in the open winding mode in the star connection mode after the switching.

Patent No. 4906836

When switching from the open winding mode to the star connection mode, if the on / off duty of the open winding mode before switching exceeds 50%, the on / off of over 100% in the star connection mode after switching It is necessary to set the duty. It is not possible to set on / off duty exceeding 100%, and it is not possible to shift to the star connection mode.

For this reason, the switching point to the star-shaped connection mode had to be set when the on / off duty of the open winding mode was 50% or less.

However, it is preferable that the switching point from the open winding mode to the star connection mode has the highest efficiency depending on the specifications of the motor, the specifications of the equipment (refrigeration cycle device), and the operating conditions. Therefore, it is desirable to be able to smoothly switch to the star connection mode even when the on / off duty of the open winding mode exceeds 50%.

An object of the embodiment of the present invention is a motor drive device and a refrigeration cycle device capable of reliably shifting from the open winding mode to the star connection mode even when the on / off duty of the open winding mode is high. Is to provide.

The motor drive device of claim 1 is a motor drive device of a motor having a plurality of phase windings that are not connected to each other; a plurality of switching elements are included, and these switching elements allow one end of each phase winding of the motor. A first inverter that controls energization to the motor; a second inverter that includes a plurality of switching elements and controls energization of the other end of each phase winding of the motor by these switching elements; With a switch connected between the ends; a star connection mode in which each phase winding is connected in a star shape by closing the switch to switch the first inverter, and the switch is opened by opening the switch. It includes a motor controller having an open winding mode for switching between the first inverter and the second inverter with each phase winding disconnected. In this motor controller, when switching from the open winding mode to the star-shaped connection mode, the set value is the voltage utilization rate corresponding to the on / off duty or the on / off duty of the switching of the open winding mode before the switching. If it exceeds, the on / off duty or voltage utilization rate is reduced to the set value or less, and after this reduction, switching from the open winding mode to the star connection mode is executed.

The figure which shows the structure of the refrigerating cycle apparatus which concerns on 1st and 2nd Embodiment. The block diagram which shows the structure of 1st and 2nd Embodiment. The block diagram which shows the structure of the inverter control part in FIG. The figure which shows the mode selection condition of 1st and 2nd Embodiment. The flowchart which shows the control of the motor controller of 1st Embodiment. The figure which shows a part of the current path in the star-shaped connection mode of 1st and 2nd embodiments. The flowchart which shows the control of the motor controller of 2nd Embodiment.

[1] The first embodiment will be described. The configuration of the refrigeration cycle device for the air conditioner according to the first embodiment is shown in FIG.

One end of the outdoor heat exchanger 3 is connected to the discharge port of the compressor 1 having the Open-Windings Motor 1M as a drive motor via a four-way valve 2, and the outdoor heat exchanger 3 is connected to the outlet. One end of the indoor heat exchanger 5 is connected to the other end by a pipe via an electric expansion valve 4 which is a compressor. The other end of the indoor heat exchanger 5 is connected to the suction port of the compressor 1 via the four-way valve 2. The outdoor fan 6 is arranged in the vicinity of the outdoor heat exchanger 3, and the indoor fan 7 is arranged in the vicinity of the indoor heat exchanger 5. The open winding motor 1M is hereinafter abbreviated as the motor 1M.

During the cooling operation, as shown by the solid arrow in FIG. 1, the gas refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3 via the four-way valve 2. The gas refrigerant flowing through the outdoor heat exchanger 3 releases heat to the outside air and condenses. The liquid refrigerant flowing out of the outdoor heat exchanger (condenser) 3 flows to the indoor heat exchanger 5 in a state of being depressurized by the electric expansion valve 4. The liquid refrigerant flowing through the indoor heat exchanger 5 takes heat from the indoor air and evaporates. The gas refrigerant flowing out of the indoor heat exchanger (evaporator) 5 is sucked into the compressor 1 through the four-way valve 2. During the heating operation, the flow path of the four-way valve 2 is switched by the controller 10, and as shown by the broken line arrow in FIG. 1, the gas refrigerant discharged from the compressor 1 exchanges indoor heat via the four-way valve 2. It flows into the vessel 5. The gas refrigerant flowing through the indoor heat exchanger 5 releases heat to the indoor air and condenses. The liquid refrigerant flowing out of the indoor heat exchanger (condenser) 5 is decompressed by the electric expansion valve 4 and flows to the outdoor heat exchanger 3. The liquid refrigerant flowing through the outdoor heat exchanger 3 takes heat from the outside air and evaporates. The gas refrigerant flowing out of the outdoor heat exchanger (evaporator) 3 is sucked into the compressor 1 through the four-way valve 2.

The controller 10 controls the four-way valve 2, the electric expansion valve 4, the outdoor fan 6, and the indoor fan 7, and also controls the driving of the motor 1M via the motor driving device 11 of the present embodiment. The motor drive device 11 includes the drive circuit 12 and the motor controller 13 shown in FIG.

The motor 1M is a permanent magnet synchronous motor having a plurality of, for example, three phase windings Lu, Lv, and Lw that are not connected to each other. The phase windings Lu, Lv, and Lw of the motor 1M are configured by winding a small diameter copper wire at a high density so as to improve efficiency in a low speed operation range (also referred to as a low / medium speed operation range). However, when the small-diameter phase windings Lu, Lv, and Lw are used, the voltage induced in the phase windings Lu, Lv, and Lw rises early as the speed of the motor 1M increases, and the induced voltage and the inverter increase. The difference from the voltage supplied to the phase windings Lu, Lv, and Lw becomes small at an early stage, and the speed of the motor 1M cannot be increased any more. Therefore, as will be described later, the motor controller 13 sets a star-shaped connection mode in which the phase windings Lu, Lv, and Lw are connected in a star shape to switch only the inverter 30 independently in the low-speed operation range, and the motor controller 13 operates at high speed. In the region, the open winding mode in which the inverters 30 and 40 are switched in cooperation with each other is set with the phase windings Lu, Lv, and Lw in the non-connected state (open state). With this setting, it is possible to obtain a wide speed variable range from the low speed operation range to the high speed operation range while enabling high efficiency operation in the low speed operation range.

[Explanation of drive circuit 12]
A diode bridge full-wave rectifier circuit 22 is connected to the three-phase AC power supply 20 via a noise filter 21, and a capacitor 24 is connected to the output end of the full-wave rectifier circuit 22 via a reactor 23. The full-wave rectifier circuit 22, the reactor 23, and the capacitor 24 constitute a DC power supply 25 that outputs a DC voltage Vdc.

An inverter (also referred to as a first inverter or a master inverter) that controls energization of one end of the phase winding Lu, Lv, Lw between the DC power supply 25 and one end of the phase winding Lu, Lv, Lw of the motor 1M. 30 is connected. An inverter (also referred to as a second inverter or a slave inverter) that controls energization of the other ends of the phase windings Lu, Lv, and Lw between the DC power supply 25 and the other ends of the phase windings Lu, Lv, and Lw of the motor 1M. ) 40 is connected. A common power supply system is adopted in which the inverters 30 and 40 are connected to a common DC power supply 25. Not limited to the common power supply method, a power supply insulation method in which the inverters 30 and 40 are connected to separate DC power supplies may be adopted.

The inverter 30 connects the switching elements, for example, the IGBTs 31 and 32 in series, and connects the IGBTs 33 and 34 in series to the U-phase series circuit in which the interconnection points of the IGBTs 31 and 32 are connected to one end of the phase winding Lu of the open winding motor 1M. A V-phase series circuit in which the interconnection points of the IGBTs 33 and 34 are connected to one end of the phase winding Lv of the open winding motor 1M, the IGBTs 35 and 36 are connected in series, and the interconnection points of the IGBTs 35 and 36 are open windings. A W-phase series circuit connected to one end of the phase winding Lw of the motor 1M is included, and the DC voltage Vdc of the DC power supply 25 is converted into a three-phase AC voltage of a predetermined frequency by switching the IGBT 31 to 36, and the three-phase AC voltage thereof. Is supplied to one end of each of the phase windings Lu, Lv, and Lw of the open winding motor 1M. Regenerative diodes (also referred to as freewheel diodes) 31a to 36a are connected in antiparallel to the IGBTs 31 to 36.

The inverter 40 connects the IGBTs 41 and 42 in series and connects the IGBTs 43 and 44 in series to the U-phase series circuit in which the interconnection points of the IGBTs 41 and 42 are connected to the other end of the phase winding Lu of the open winding motor 1M. A V-phase series circuit in which the interconnection points of the IGBTs 43 and 44 are connected to the other end of the phase winding Lv of the motor 1M, the IGBTs 45 and 46 are connected in series, and the interconnection point of the IGBTs 45 and 46 is the phase of the open winding motor 1M. A W-phase series circuit connected to the other end of the winding Lw is included, and the DC voltage Vdc of the DC power supply 25 is converted into a three-phase AC voltage of a predetermined frequency by switching the IGBTs 41 to 46, and the three-phase AC voltage is converted to the motor 1M. It is supplied to the other end of each of the phase windings Lu, Lv, and Lw. Regenerative diodes (also referred to as freewheel diodes) 41a to 46a are connected in antiparallel to the IGBTs 41 to 46.

The inverter 30 contains a main circuit in which three sets of series circuits of two switching elements are connected in parallel and peripheral circuits such as a drive circuit for driving the six switching elements of the main circuit in a single package. This is a so-called IPM (Intelligent Power Module). The inverter 40 is also an IPM having the same configuration.

A switch, for example, a normally open contact (referred to as a relay contact) 51a of a switch 51 is connected between the other end of the phase winding Lu of the motor 1M and the other end of the phase winding Lv. A switch, for example, a normally open contact (referred to as a relay contact) 52a of a switch 52, for example, is connected between the other end of the phase winding Lv of the motor 1M and the other end of the phase winding Lw. The relays 51 and 52 are urged and de-energized by the motor controller 13 in a state of being synchronized with each other. When the relay contacts 51a and 52a are closed, the other ends of the phase windings Lu, Lv and Lw are interconnected and the phase windings Lu, Lv and Lw are in a star-shaped connection state. The interconnection point at the other ends of the phase windings Lu, Lv, and Lw is the neutral point of the star connection. When the relay contacts 51a and 52a are opened, the phase windings Lu, Lv and Lw are disconnected (open state) and the phase windings Lu, Lv and Lw are electrically separated.

Current sensors 53, 53v, 53w are arranged on each energizing line between the inverter 30 and the motor 1M, and the detection signals of these current sensors 53, 53v, 53w are sent to the motor controller 13. The motor controller 13 controls the drive circuit 12 in response to a command from the controller 10, and is a main control unit 60, a voltage detection unit 61, an inverter control unit 62, a relay drive unit 63, a relay 51, which are the centers of control. Including 52 and the like. The voltage detection unit 61 detects the output voltage Vdc of the DC power supply 25. The relay drive unit 63 urges or deenergizes the relays 51 and 52 in response to a command from the main control unit 60.

The inverter control unit 62 estimates the speed (rotation speed) ωest of the motor 1M based on the detection results of the current sensors 53, 53v, 53w, and the inverters 30, 40 according to the difference between the estimated speed ωest and the target speed ωref. As shown in FIG. 3, the current detection unit 71, the speed estimation calculation unit 72, the integration unit 73, the subtraction unit 74, the speed control unit 75, the Id control unit 76, and the subtraction are performed. It includes units 77 and 78, current control units 81 and 82, and PWM signal generation unit 83.

The current detection unit 71 captures the current (motor current) flowing through the phase windings Lu, Lv, Lw of the motor 1M from the outputs of the current sensors 53, 53v, 53w, and the field component (d-axis component) Id of the captured current. And the torque component (q-axis component) Iq is detected. The field component Id of the current is called the field component current Id, and the torque component Iq of the current is called the torque component current Iq. The field component current Id is a current converted into field axis (d-axis) coordinates on the rotor axis, and is also called a d-axis current or a reactive current. The torque component current Iq is a current converted into torque axis (q-axis) coordinates on the rotor shaft, and is also called a q-axis current or an effective current. The data of the field component current Id and the torque component current Iq are sent to the integrating unit 73, the subtracting unit 74, and the main control unit 60.

The speed estimation calculation unit 72 estimates the speed (rotational speed of the rotor) ωest of the motor 1M by calculation based on the field component current Id and the torque component current Iq. The data of the estimated speed ωest is sent to the integrating unit 73 and the main control unit 60. The integrating unit 73 detects the rotor position θest of the motor 1M by integrating the estimated speed ωest. The data of the rotor position θest is sent to the current detection unit 71, the PWM signal generation unit 83, and the main control unit 60. The subtraction unit 74 obtains the deviation ωerr between the target speed ωref and the estimated speed ωest by subtracting the estimated speed ωest from the target speed ωref set by the main control unit 60. The data of this deviation ωerr is sent to the speed control unit 75.

The speed control unit 75 obtains the target value Iqref of the torque component current Iq by calculating the deviation ωerr in proportional / integral control (PI control). The data of the target value Iqref is sent to the Id control unit 76. The Id control unit 76 obtains the target value Idref of the field component current Id from the target value Iqref. The data of the target value Idref is sent to the subtraction unit 77. The Id control unit 76 has a predetermined level of negative field control when the main control unit 60 commands the execution of the field weakening control for injecting the negative field component current “−Id” into the phase windings Lu, Lv, Lw. The field component current "-Id" of is added to the above-determined target value Idref. The subtraction unit 77 obtains the deviation ΔId between the target value Idref and the field component current Id. The subtraction unit 78 obtains the deviation ΔIq between the target value Iqref and the torque component current Iq. The data of the deviations ΔId and ΔIq are sent to the current control units 81 and 82, respectively.

The current control unit 81 obtains the field component (d-axis component) Vd of the drive voltage to be supplied to the motor 1M by calculating the deviation ΔId in proportional / integral control (PI control). This field component voltage Vd is a voltage converted into field axis (d axis) coordinates on the rotor axis, and is also called a d-axis voltage or an invalid voltage. The current control unit 82 obtains the torque component (q-axis component) Vq of the drive voltage to be supplied to the motor 1M by calculating the deviation ΔIq in proportional / integral control (PI control). This torque component voltage Vq is a voltage converted into torque axis (q-axis) coordinates on the rotor axis, and is also called a q-axis voltage or an effective voltage. The data of the field component voltage Vd and the torque component voltage Vq are sent to the PWM signal generation unit 83 and the main control unit 60.

When the main control unit 60 sets the star connection mode, the PWM signal generation unit 83 sets the PWM signal (pulse width modulation signal) P1 for switching the inverter 30 independently, the field component voltage Vd, and the torque component voltage. Generated based on Vq, rotor position θest, etc. Further, when the main control unit 60 sets the open winding mode, the PWM signal generation unit 83 transmits the PWM signal P2 for switching the inverters 30 and 40 in cooperation with each other with the field component voltage Vd and the torque component voltage. Generated based on Vq, rotor position θest, etc. The switching elements of the inverters 30 and 40 operate on and off according to the generated PWM signals P1 and P2. The on / off-duty Du1 and Du2 data of the PWM signals P1 and P2 are sent to the main control unit 60.

The main control unit 60 is composed of a microcomputer and its peripheral circuits. The relay contacts 51a and 52a are opened and closed and the inverter is opened and closed according to a command from the controller 10, a detection result of the voltage detection unit 61, a control content of the inverter control unit 62, and the like. It controls the switching of 30 and 40, and includes a first control unit 60a, a second control unit 60b, and a third control unit 60c.

The first control unit 60a sets the target speed ωref of the motor 1M according to the air conditioning load notified from the controller 10, and commands the set target speed ωref to the inverter control unit 62. Further, when the on / off duty Du1 and Du2 of the PWM signals P1 and P2 generated by the inverter control unit 62 reach the upper limit value in the control, the first control unit 60a cannot increase the motor speed. In order to enable the motor speed to be further increased, the inverter control unit 62 is instructed to perform field weakening control in which a negative field component current “−Id” is applied to the phase windings Lu, Lv, and Lw.

The second control unit 60b has a star-shaped connection mode in which the phase windings Lu, Lv, and Lw are connected in a star shape by closing the relay contacts 51a and 52a to switch only the inverter 30 independently, and the relay contacts 51a and 52a. The open winding mode in which the inverters 30 and 40 are switched in cooperation with each other with the phase windings Lu, Lv, and Lw disconnected (open state) by opening is stored in the estimated speed ωest of the inverter control unit 62 and the internal memory. It is selectively set by referring to the mode selection condition of FIG.

The mode selection condition specifies a highly efficient star-shaped connection mode when the estimated speed ωest changes in the ascending direction and the estimated speed ωest is in the low-speed operating range less than the threshold ωest2, and the estimated speed ωest is the threshold ωest2 or more. If it is in the high speed operating range, specify the open winding mode. As for the mode selection condition, when the estimated speed ωest changes in the descending direction, the open winding mode is specified when the estimated speed ωest exists in the high speed operation range exceeding the threshold value ωest1 (<ωest2), and the estimated speed ωest is the threshold value. If it exists in the low speed operation range of ωest1 or less, specify the star connection mode.

When the second control unit 60b switches from the open winding mode to the star connection mode, the third control unit 60c sets the switching of the open winding mode before switching to on, off-duty Du2 or its on, off-duty Du2. When the corresponding voltage utilization rate X is equal to or less than the set value (for example, 50%), the second control unit 60b immediately allows (executes) switching from the open winding mode to the star-shaped connection mode. Further, when the second control unit 60b switches from the open winding mode to the star connection mode, the third control unit 60c turns on the switching of the open winding mode before switching, and off-duty Du2 or its on-off duty. When the voltage utilization rate X corresponding to Du2 exceeds the above set value, the on / off duty Du2 or the voltage utilization rate X is lowered to the above set value or less by lowering the target speed ωref, and after this decrease. , Allows (executes) switching from the open winding mode to the star connection mode by the second control unit 60b. Further, the third control unit 60c releases the decrease in the target speed ωref after the switching from the open winding mode to the star connection mode by the second control unit 60b is completed.

The third control unit 60c recognizes one rotation of the motor 1M based on the rotor position θest detected by the inverter control unit 62, and of the on / off-duty Du2 and the voltage utilization rate X during the one rotation, The maximum on / off duty Du2 or the maximum voltage utilization rate X is used to determine whether or not it is equal to or less than the above set value.

The voltage utilization rate X is supplied as data from the inverter control unit 62 by the ratio of the voltage output from the inverters 30 and 40 to the rated maximum output voltage of the inverters 30 and 40 according to the on / off duty Du2. It can be obtained by the calculation of the following equation (1) using the field component voltage Vd and the torque component voltage Vq.

Next, the control executed by the motor controller 13 will be described with reference to the flowchart of FIG. Steps S1, S2 ... In the flowchart are simply abbreviated as S1, S2 ...

[Star-shaped connection mode]
When the operation start command is received from the controller 10 (YES in S1), the motor controller 13 closes the relay contacts 51a and 52a, connects the phase windings Lu, Lv, and Lw in a star shape, and connects the inverter 30 independently. The star-shaped connection mode to be switched is set (S2).

A part of the current path formed in this star-shaped connection mode is shown in FIG. First, the IGBT 31 on the upstream side of the inverter 30 is turned on, and the IGBTs 34 and 36 on the downstream side are repeatedly turned on and off of the on and off duty Du1 while synchronizing with each other. As a result, as shown by the broken line arrow, a current flows from the positive terminal of the DC power supply 25 through the IGBT 31 to the phase winding Lu, and the current passing through the phase winding Lu passes through the relay contacts 51a and 52a and is phase-wound. The current flows through the lines Lv and Lw, and the current passing through these phase windings Lv and Lw flows through the IGBTs 34 and 36 to the negative terminal of the DC power supply 25. Next, the IGBT 33 on the upstream side of the inverter 30 is turned on, and the IGBTs 32 and 36 on the downstream side are repeatedly turned on and off of the on and off duty Du1 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 through the IGBT 33 to the phase winding Lv, and the current passing through the phase winding Lv flows to the phase windings Lu and Lw through the relay contacts 51a and 52a. The current passing through these phase windings Lu and Lw flows through the IGBTs 32 and 36 to the negative terminal of the DC power supply 25. Next, the IGBT 35 on the upstream side of the inverter 30 is turned on, and the IGBTs 32 and 34 on the downstream side are repeatedly turned on and off of the on and off duty Du1 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 through the IGBT 35 to the phase winding Lw, and the current passing through the phase winding Lw flows to the phase windings Lu and Lv through the relay contacts 51a and 52a. The current passing through these phase windings Lu and Lv flows through the IGBTs 32 and 34 to the negative terminal of the DC power supply 25. By sequentially switching the current paths of these three patterns, the rotor of the motor 1M rotates. In this case, the inverter 40 is held in a stopped state, that is, a state in which the switching operation is not performed. When the motor 1M is started in this star-shaped connection mode, the motor controller 13 determines whether or not the estimated speed ωest has risen to the threshold value ωest2 (S4). While the estimated speed ωest is lower than the threshold value ωest2 (NO in S4, NO in S5), the motor controller 13 returns to S3 if there is no stop command from the controller 10 (NO in S12), and the estimated speed ωest becomes The switching on / off duty Du1 of the inverter 30 is controlled so that the target speed ωref is obtained (S3).

[Switching from star connection mode to open winding mode]
In the star connection mode, when the target speed ωref increases and the estimated speed ωest increases and reaches the threshold value ωest2 (high rotation speed region; YES in S4), that is, from the star connection mode to the open winding mode. When the state where switching to is required is reached, the motor controller 13 sets the other ends of the phase windings, phase windings Lu, Lv, and Lw in a non-connected (open: open) state by opening the relay contacts 51a and 52a, and sets the inverter 30. , 40 are switched in cooperation with each other to set an open winding mode (S6). Then, if there is no operation stop command from the controller 10 (NO in S12), the motor controller 13 shifts to the above S3, and the switching on / off duty of the inverters 30 and 40 is set so that the estimated speed ωest becomes the target speed ωref. Du2 is controlled (S3).

A part of the current path in this open winding mode is shown by a broken line in FIG. First, the upstream side IGBT 31 of the inverter 30 is turned on, the downstream side IGBT 42 of the inverter 40 is turned on and the off-duty Du2 is turned on and off repeatedly, and the upstream side IGBTs 43 and 45 of the inverter 40 are both turned on and the inverter. The downstream side IGBTs 34 and 36 in 30 repeat the on and off duty Du2 on and off while synchronizing with each other. As a result, as shown by the broken line arrow, a current flows from the positive terminal of the DC power supply 25 through the IGBT 31 to the phase winding Lu, and the current passing through the phase winding Lu passes through the IGBT 42 to the negative side of the DC power supply 25. Along with flowing to the terminal, a current flows from the positive terminal of the DC power supply 25 through the IGBTs 43 and 45 to the phase windings Lv and Lw, and the current passing through the phase windings Lv and Lw passes through the IGBTs 34 and 36 and the DC power supply 25. Flows to the negative terminal of. Next, the upstream side IGBT 33 of the inverter 30 is turned on, the downstream side IGBT 44 of the inverter 40 is turned on and the off-duty Du2 is turned on and off repeatedly, and the upstream side IGBTs 41 and 45 of the inverter 40 are turned on together. The IGBTs 32 and 36 on the downstream side of the inverter 30 repeatedly turn on and off the on and off duty Du2 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 through the IGBT 33 to the phase winding Lv, and the current passing through the phase winding Lv flows through the IGBT 44 to the negative terminal of the DC power supply 25 and the DC power supply. A current flows from the positive terminal of 25 through the IGBTs 41 and 45 to the phase windings Lu and Lw, and a current passing through the phase windings Lu and Lw flows through the IGBTs 32 and 36 to the negative terminal of the DC power supply 25. Next, the upstream side IGBT 35 of the inverter 30 is turned on, the downstream side IGBT 46 of the inverter 40 is turned on and the off-duty Du2 is turned on and off repeatedly, and the upstream side IGBTs 41 and 43 of the inverter 40 are turned on together. The IGBTs 32 and 34 on the downstream side of the inverter 30 repeat the on and off duty Du2 on and off while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 through the IGBT 35 to the phase winding Lw, and the current passing through the phase winding Lw flows through the IGBT 46 to the negative terminal of the DC power supply 25 and the DC power supply. A current flows from the positive terminal of 25 through the IGBTs 41 and 43 to the phase windings Lu and Lv, and a current passing through the phase windings Lu and Lv flows through the IGBTs 32 and 34 to the negative terminal of the DC power supply 25. By switching the current paths of these three patterns in order, the rotor of the motor 1M rotates.

By setting this open winding mode, a high level voltage of about 1.7 times that in the star connection mode is applied to the phase windings Lu, Lv, and Lw, and the motor 1M can be rotated at a high speed.

When the operation stop command is received from the controller 10 (YES in S12), the motor controller 13 stops the switching of the inverters 30 and 40 (S13).

[Switching from open winding mode to star connection mode]
In the open winding mode, when the estimated speed ωest decreases as the target speed ωref decreases and reaches the threshold value ωest1 (low rotation speed region; NO in S4, YES in S5), that is, a star shape from the open winding mode. When switching to the connection mode is required, the motor controller 13 monitors whether the on / off duty Du2 is 50% or less of the set value (S7).

When the on / off duty Du2 of the open winding mode is 50% or less, for example 40%, the same level voltage as in the open winding mode is applied to the phase winding Lu, Lv, Lw in the star-shaped connection mode after switching. In order to apply it, it is necessary to set 80% (= 40% × 2) on / off duty Du1 in the star-shaped connection mode after switching. The 80% on / off duty Du1 can be set in the star connection mode.

Therefore, when the open winding mode on / off duty Du2 is 50% or less (YES in S7), the motor controller 13 connects the phase windings Lu, Lv, and Lw in a star shape by closing the relay contacts 51a and 52a. Then, the star-shaped connection mode for switching the inverter 30 independently is immediately set (S9). In this way, after the switching from the open winding mode to the star-shaped connection mode is completed, the motor controller 13 confirms whether or not there is a reduction process of the target speed ωref by S8 described later (S10). At this point, since there is no reduction process of the target speed ωref (NO in S10), the motor controller 13 confirms the operation stop command from the controller 10 without executing the next release process of S11 (S12).

When there is no operation stop command (NO in S12), the motor controller 13 shifts to S3 and controls the switching on / off duty Du1 of the inverter 30 so that the estimated speed ωest becomes the target speed ωref (S3).

On the other hand, when the on / off duty Du2 of the open winding mode exceeds 50%, for example, 55%, the same level voltage as in the open winding mode is applied in the star-shaped connection mode after switching to the phase winding Lu, Lv, In order to apply to Lw, it is necessary to set 110% (= 55% × 2) on / off duty Du1 in the star-shaped connection mode after switching. Of course, on / off duty Du1 exceeding 100% cannot be set.

Therefore, when the on / off duty Du2 in the open winding mode exceeds 50% (NO in S7) as in the case of 55%, the motor controller 13 reduces the target speed ωref by a predetermined value (S8). .. Due to this decrease in the target speed ωref, the on / off duty Du2 in the open winding mode changes in the decreasing direction. Subsequently, the motor controller 13 returns to S7 and monitors whether or not the on / off duty Du2 is 50% or less (S7).

When the on / off duty Du2 still exceeds 50% (NO in S7) even though the target speed ωref is lowered, the motor controller 13 further lowers the target speed ωref by a predetermined value (S8). .. Then, the motor controller 13 returns to S7 and monitors again whether or not the on / off duty Du2 is 50% or less (S7). The motor controller 13 repeats the processes of S7 and S8 until the on / off duty Du2 is reduced to 50% or less. The decrease in the target speed ωref due to S8 is a temporary measure, and the original target speed ωref is based on an external command and exists as it is.

When the on / off duty Du2 of the open winding mode drops to 50% or less, for example, 48%, the same level voltage as in the open winding mode is applied in the star connection mode after switching to the phase winding Lu, Lv, Lw. It is necessary to set 96% (= 48% × 2) on / off duty Du1 in the star-shaped connection mode after switching. 96% on-duty Du1 can be set in star connection mode.

Therefore, when the on / off duty Du2 in the open winding mode is reduced to 48% or less, which is 50% or less (YES in S7), the motor controller 13 closes the relay contacts 51a and 52a to 96%. The star-shaped connection mode is set by switching the inverter 30 independently with the on / off duty Du1 (S9). In this way, after the switching from the open winding mode to the star connection mode is completed, the motor controller 13 confirms whether or not there is a reduction process of the target speed ωref in S8 (S10). At this point, since there is a reduction process of the target speed ωref (YES in S10), the motor controller 13 cancels the reduction of the target speed ωref (S11). As a result, the target speed ωref returns to the original target speed ωref based on an external command. After this release, the motor controller 13 confirms the operation stop command from the controller 10 (S12).

When there is no operation stop command from the controller 10 (NO in S12), the motor controller 13 shifts to the above S3 and turns on / off-duty Du1 of the switching of the inverter 30 so that the estimated speed ωest becomes the original target speed ωref. Controlled (S3), if the target speed ωref has been lowered before, the speed is increased so as to return to the original speed. When the operation stop command is received from the controller 10 (YES in S12), the motor controller 13 stops the switching of the inverter 30 (S13).

As described above, when switching from the open winding mode to the star connection mode, if the on / off duty Du2 (or voltage utilization rate X) of the open winding mode exceeds the set value, the on / off duty Du2 (or voltage utilization rate X) is lowered below the set value, and after this drop, switching from the open winding mode to the star connection mode is executed, so what value is the on / off duty of the open winding mode? Even so, it is possible to reliably shift from the open winding mode to the star connection mode.

The motor controller 13 switches both of the inverters 30 and 40 so as to coordinately synchronize the inverters 30 and 40 when switching from the open winding mode to the star connection mode and switching from the star connection mode to the open winding mode. Control. As a result, switching between the open winding mode and the star connection mode is completed without stopping the motor 1M.

Further, when switching between the open winding mode and the star-shaped connection mode, the motor controller 13 appropriately controls the switching of the inverters 30 and 40 so that no current flows through the relay contacts 51a and 52a, and the relay contacts 51a and 52a. Opens and closes. Since the relay contacts 51a and 52a open and close while no current flows through the relay contacts 51a and 52a, it is possible to prevent sparks from occurring at the relay contacts 51a and 52a, and eventually to prevent failures such as welding of the relay contacts 51a and 52a. It can be avoided.

A decrease in on / off-duty Du2 (or voltage utilization rate X) leads to a decrease in motor speed, but the amount of decrease in on / off-duty Du2 (or voltage utilization rate X) is a small amount until it falls below the set value. Moreover, since the decrease in on / off duty Du2 (or voltage utilization rate X) is temporary at the time of mode switching, the decrease in motor speed can be almost ignored in terms of both magnitude and time.

[2] A second embodiment will be described.

In the second embodiment, the control / operation at the time of switching from the open winding mode to the star-shaped connection mode is different from that in the first embodiment. Others are the same as in the first embodiment.

When the second control unit 60b switches from the open winding mode to the star connection mode, the third control unit 60c of the main control unit 60 turns on the switching of the open winding mode before switching, and off-duty Du2 (or voltage). When the utilization rate X) is equal to or less than the set value (for example, 50%), the second control unit 60b immediately allows (executes) switching from the open winding mode to the star-shaped connection mode. Further, in the third control unit 60c, when the second control unit 60b switches from the open winding mode to the star-shaped connection mode, the on / off duty Du2 of the switching of the open winding mode before the switching exceeds the above set value. If so, the on / off duty Du2 is lowered to the above set value or less by executing the field weakening control in which a negative field component current is applied to each of the phase windings, and then the open winding by the second control unit 60b is performed. Allows (executes) switching from line mode to star connection mode. Further, the third control unit 60c releases the decrease in the target speed ωref after the switching from the open winding mode to the star connection mode by the second control unit 60b is completed.

Normally, field weakening control further increases the rotation speed when the motor rotates at high speed and the on / off duty is 100%, the induced voltage of the winding increases, and the rotation speed cannot be increased any more. However, in the present embodiment, it is used to reduce the on / off duty Du2 while keeping the rotation speed of the motor constant.

As shown in the flowchart of FIG. 7, the motor controller 13 executes the processes of S8', S10', and S11'instead of the processes of S8, S10, and S11 of the flowchart of FIG.

That is, when the motor controller 13 needs to switch from the open winding mode to the star connection mode, and the on / off duty Du2 of the open winding mode exceeds the set value of 50% (S7). NO), field weakening control is performed by injecting a negative field component current “−ΔId” of a predetermined magnitude into the phase windings Lu, Lv, Lw (S8 ′). This weakening field control reduces the on / off duty Du2 of the open winding mode.

After injecting the negative field component current “−ΔId”, the motor controller 13 returns to S7 and monitors again whether the on / off duty Du2 reaches 50% or less (S7).

If the on / off duty Du2 still exceeds 50% (NO in S7) despite the injection of the negative field component current “−ΔId”, the motor controller 13 further has a predetermined magnitude of negative. The field component current “−ΔId” of the above is further injected into the phase windings Lu, Lv, and Lw (S8 ′). As a result, the negative field component current is doubled to "-2 · ΔId".

As a result, when the motor 1M is rotated at the same speed, the on / off duty Du2 is further reduced. Then, the motor controller 13 returns to S7 and monitors again whether or not the on / off duty Du2 is 50% or less (S7). The process of S7 and S8'is repeated until the on / off duty Du2 is reduced to 50% or less, and the negative field component current is increased.

When the on / off duty Du2 drops to 50% or less (YES in S7), the motor controller 13 closes the relay contacts 51a and 52a and sets the star connection mode instead of the open winding mode up to that point. (S9). Then, the motor controller 13 confirms whether or not there is the field weakening control of S8'(S10'). At this point, since the field weakening control is included (YES in S10'), the motor controller 13 subsequently shifts to the field weakening control in the star connection mode, and the field weakening amount (negative field component current "". -ΔId ") is adjusted (S11'), whereby the speed of the motor 1M is appropriately controlled. After that, the motor controller 13 confirms the operation stop command from the controller 10 (S12).

As described above, when switching from the open winding mode to the star connection mode, if the on / off duty Du2 (or voltage utilization rate X) of the open winding mode exceeds the set value, its negative field. By executing field weakening control that injects the component current "-Id", the on / off-duty Du2 (or voltage utilization rate X) is lowered, and after the on / off-duty Du2 drops to 50% or less, the star is released from the open winding mode. Since the switching to the shape connection mode is executed, it is possible to reliably shift from the open winding mode to the star connection mode without changing (decreasing) the motor speed as in the first embodiment. As a result, the stability of the refrigeration cycle is enhanced.

Other configurations and controls are the same as in the first embodiment.

[Modification example]
In each of the above embodiments, the case where the set value for the on / off duty Du2 (or the maximum voltage utilization rate X) is 50% has been described as an example, but the set value is appropriately selected within the range of 50% or less. It is possible.

Further, in each of the above embodiments, as a mode selection condition, switching from the open winding mode to the star-shaped connection mode is performed according to the estimated speed ωest, but the open winding mode is changed to the star according to the target speed ωref. Switching to the shape connection mode may be performed. The threshold value, which is the switching point from the open winding mode to the star connection mode, may be variably set according to the refrigeration cycle condition and the motor current value. In addition, the open winding mode may be switched to the star connection mode based on data other than the motor speed such as the estimated speed ωest and the target speed ωref. In the first embodiment, the on / off duty Du2 (or voltage utilization rate X) is reduced by the operation of lowering the target speed ωref, but the PWM signal P2 generated by the inverter control unit 62 is turned on / off duty. The Du2 (or the voltage utilization rate X) may be directly lowered.

In each of the above embodiments, the case where the switch has relay contacts 51a and 52a has been described as an example, but a semiconductor switch can also be used as the switch.

In each of the above embodiments, the open winding motor used as the driving motor of the compressor has been described as an example, but the same can be applied to the open winding motor used for other purposes.

In each of the above embodiments, a case where a three-phase inverter device composed of six switching elements is used as the inverter 30 and a three-phase inverter device composed of six switching elements is used as the inverter 40 has been described as an example, but from four switching elements The inverter 30 and the inverter 40 may be configured by using three single-phase inverter devices.

Further, the reduction of the on / off duty Du2 (or the voltage utilization rate X) at the time of switching from the open winding mode to the star connection mode is reduced at the same time as the rotation speed of the motor 1M as in the first embodiment. 2 It may be executed by adding the field weakening control in the embodiment.

In addition, each of the above embodiments and modifications is presented as an example, and is not intended to limit the scope of the invention. Each of the novel embodiments and modifications can be implemented in various other forms, and various omissions, rewrites, and changes can be made without departing from the gist of the invention. These embodiments and modifications are included in the gist of the invention as well as in the scope of the invention described in the claims and the equivalent scope thereof.

1 ... Compressor, 1M ... Open winding motor, Lu, Lv, Lw ... Phase winding, 2 ... Four-way valve, 3 ... Outdoor heat exchanger, 4 ... Electric expansion valve, 5 ... Indoor heat exchanger, 10 ... Controller , 11 ... Motor drive device, 12 ... Drive circuit, 13 ... Motor controller, 20 ... 3-phase AC power supply, 25 ... DC power supply, 30 ... Inverter (first inverter), 40 ... Inverter (second inverter), 51, 52 ... Relay, 51a, 52a ... Relay contact, 60 ... Main control unit, 62 ... Inverter control unit, 63 ... Relay drive unit

Claims (7)

A motor drive for a motor that has multiple phase windings that are disconnected from each other.
A first inverter that includes a plurality of switching elements and controls the energization of one end of each phase winding of the motor by these switching elements.
A second inverter that includes a plurality of switching elements and controls the energization of the other end of each phase winding of the motor by these switching elements.
A switch connected between the other ends of each phase winding and
A star-shaped connection mode in which each phase winding is connected in a star shape by closing the switch to switch the first inverter, and the first phase winding is disconnected by opening the switch. A motor controller having an open winding mode for switching the inverter and the second inverter,
With
The motor controller is
When switching from the open winding mode to the star connection mode, when the voltage utilization rate corresponding to the on / off duty or its on / off duty of the switching of the open winding mode before the switching exceeds the set value. , The motor drive device characterized in that the on / off duty or the voltage utilization rate is lowered to the set value or less, and after the reduction, the switching from the open winding mode to the star connection mode is executed. The motor controller is
When switching from the open winding mode to the star connection mode, when the voltage utilization rate corresponding to the on / off duty or the on / off duty of the switching of the open winding mode before the switching is equal to or less than the set value, The motor drive device according to claim 1, wherein the switching from the open winding mode to the star connection mode is immediately executed. The motor controller is
A star-shaped connection mode in which each phase winding is connected in a star shape by closing the switch, the first inverter is switched, and the on / off duty of this switching is controlled so that the speed of the motor becomes the target speed. By opening the switch, the first inverter and the second inverter are switched with each phase winding disconnected, and the on / off duty of this switching is controlled so that the speed of the motor becomes the target speed. The motor drive device according to claim 1, wherein the open winding mode to be used is selectively set. The motor controller is
When switching from the open winding mode to the star connection mode, the voltage utilization rate corresponding to the on / off duty or the on / off duty of the switching of the open winding mode before the switching exceeds the set value. In this case, the on / off duty or voltage utilization rate of the motor is reduced to the set value or less by reducing the speed of the motor, and then the switching from the open winding mode to the star connection mode is executed. The motor drive device according to claim 1. The controller
When switching from the open winding mode to the star connection mode, the voltage utilization rate corresponding to the on / off duty or the on / off duty of the switching of the open winding mode before the switching exceeds the set value. In this case, the on / off duty or voltage utilization rate is reduced to the set value or less by executing a field weakening control in which a negative field component current is applied to each of the phase windings, and then the open winding mode is performed. The motor drive device according to claim 1, wherein the switching to the star connection mode is performed. The controller
Any one of claims 1 to 5, wherein the star-shaped connection mode is set in the low-speed operation range of the motor, and the open winding mode is set in the high-speed operation range of the motor. The motor drive device according to. A refrigeration cycle device including the motor drive device according to claim 1.
A compressor that has the open winding motor as a drive motor and sucks in refrigerant, compresses it, and discharges it.
The compressor, the four-way valve, the condenser, the decompressor, and the evaporator are connected by piping, and the refrigerant discharged from the compressor is passed through the four-way valve, the condenser, the decompressor, and the evaporator to compress the compressor. A heat pump refrigeration cycle that returns to the suction side of the machine,
A refrigeration cycle device characterized by being equipped with.

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