WO2020059095A1

WO2020059095A1 - Motor driving device and refrigeration cycle device

Info

Publication number: WO2020059095A1
Application number: PCT/JP2018/034902
Authority: WO
Inventors: 雅也野木; 嘉隆内山
Original assignee: 東芝キヤリア株式会社
Priority date: 2018-09-20
Filing date: 2018-09-20
Publication date: 2020-03-26
Also published as: JP6980930B2; JPWO2020059095A1

Abstract

If, at the time of a switchover from open winding mode to star connection mode, the on/off duty (or voltage utilization rate) of the switching of the pre-switchover open winding mode exceeds a set value, a motor controller lowers the on/off duty (or voltage utilization rate) to or below the set value, and after the lowering, executes a switchover from the open winding mode to the star connection mode.

Description

Motor drive device and refrigeration cycle device

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

永久 A permanent magnet synchronous motor having a plurality of phase windings is used as a motor for driving a compressor mounted on a refrigeration cycle device such as an air conditioner or a heat source device. 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.

A motor drive device that drives this open-winding motor (abbreviated as a motor) includes a first inverter that controls energization of one end of each phase winding of the motor, and energization of the other end of each phase winding of the motor. A second inverter to be controlled and a switch connected between the other ends of the respective phase windings are provided. By closing the switches, each phase winding is star-connected and only the first inverter is independently switched. The open winding mode in which the first inverter and the second inverter are switched in cooperation with each other by setting the respective phase windings to a disconnected state (open state) by opening the switch, is selectively set. .

In the open winding mode, a high-level voltage approximately twice as high as that in the star connection mode can be applied to each phase winding. In this case, the star connection mode is set, and the ON / OFF duty of the independent switching of the first inverter is controlled so that the motor speed becomes the target speed. In a high speed operation region where the motor speed is equal to or higher than a threshold, 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 motor speed becomes the target speed. By switching in this manner, operation at a high rotation speed becomes possible, and high efficiency can be obtained in a wide operation speed range.

When switching from the star connection mode to the open winding mode without stopping the motor and continuing operation without stopping the motor, when the open winding mode after the switching is turned on, the ON / OFF of the 1/2 of the star connection mode is performed. Set the off duty. Conversely, when switching from the open winding mode to the star connection mode, in the switched star connection mode, on / off duty twice as high as in the open winding mode is set.

Patent No. 4990636

When switching from open winding mode to star connection mode, if the on / off duty of open winding mode before switching exceeds 50%, on / off exceeding 100% in star connection mode after switching It is necessary to set the duty. It is impossible to set the 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 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 be the highest efficiency depending on the motor specifications, the specifications of the equipment (refrigeration cycle device) and the operating conditions. Accordingly, it is desired that the open winding mode can be smoothly switched to the star connection mode even when the on / off duty exceeds 50%.

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

The motor drive of claim 1 is a motor drive for a motor having a plurality of phase windings disconnected from each other; including a plurality of switching elements, one end of each phase winding of the motor by the switching elements. A first inverter for controlling energization of the motor; a second inverter including a plurality of switching elements, and controlling the energization of the other end of each phase winding of the motor by the switching elements; A switch connected between the ends; a star connection mode in which each phase winding is star-connected by closing the switch and the first inverter is switched; and the switch is opened by opening the switch. A motor controller having an open winding mode for switching the first inverter and the second inverter with each phase winding being in a non-connected state. When switching from the open winding mode to the star connection mode, the motor controller sets an on / off duty of switching in the open winding mode before switching or a voltage utilization rate corresponding to the on / off duty to a set value. Is exceeded, the on / off duty or the voltage utilization rate is reduced to the set value or less, and after this reduction, the switching from the open winding mode to the star connection mode is executed.

The figure which shows the structure of the refrigeration cycle apparatus which concerns on 1st and 2nd embodiment. FIG. 2 is a block diagram showing a configuration of the first and second embodiments. FIG. 3 is a block diagram illustrating a configuration of an inverter control unit in FIG. 2. FIG. 6 is a diagram illustrating mode selection conditions according to the first and second embodiments. 5 is a flowchart illustrating control of the motor controller according to the first embodiment. The figure which shows a part of electric current path at the time of the star connection mode of 1st and 2nd embodiment. 9 is a flowchart illustrating control of the motor controller according to the second embodiment.

[1] The first embodiment will be described. FIG. 1 shows a configuration of a refrigeration cycle device for an air conditioner according to the first embodiment.

One end of an outdoor heat exchanger 3 is connected to a discharge port of a compressor 1 having an open-winding motor 1M as a driving motor via a four-way valve 2 by piping. One end of the indoor heat exchanger 5 is connected to the other end via an electric expansion valve 4 which is a pressure reducer. 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 by piping. An outdoor fan 6 is arranged near the outdoor heat exchanger 3, and an indoor fan 7 is arranged near the indoor heat exchanger 5. The open winding motor 1M is hereinafter abbreviated as the motor 1M.

時 During the cooling operation, the gas refrigerant discharged from the compressor 1 flows to the outdoor heat exchanger 3 via the four-way valve 2 as shown by a solid line arrow in FIG. The gas refrigerant flowing to the outdoor heat exchanger 3 emits 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 while being decompressed by the electric expansion valve 4. The liquid refrigerant that has flowed into the indoor heat exchanger 5 evaporates by removing heat from the indoor air. The gas refrigerant flowing out of the indoor heat exchanger (evaporator) 5 is drawn 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 so that the gas refrigerant discharged from the compressor 1 is subjected to the indoor heat exchange through the four-way valve 2 as shown by a dashed arrow in FIG. Flow into vessel 5 The gas refrigerant flowing into the indoor heat exchanger 5 emits 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 that has flowed into the outdoor heat exchanger 3 evaporates by removing heat from the outside air. The gas refrigerant flowing out of the outdoor heat exchanger (evaporator) 3 is drawn 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 controls the driving of the motor 1M via the motor driving device 11 of the present embodiment. The motor drive device 11 includes a drive circuit 12 and a 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, 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 that the efficiency is improved 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 increases as the speed of the motor 1M increases, and the induced voltage and the inverter The difference between the voltage supplied to the phase windings Lu, Lv, and Lw decreases at an early stage, and the speed of the motor 1M cannot be increased any more. Therefore, the motor controller 13 sets a star connection mode in which the phase windings Lu, Lv, and Lw are star-connected in the low-speed operation range and only the inverter 30 is switched alone in a low-speed operation range, as described later. In the region, an open winding mode in which the phase windings Lu, Lv, and Lw are disconnected (open state) to switch the

inverters

30 and 40 in cooperation with each other is set. With this setting, it is possible to obtain a wide speed variable width from the low-speed operation range to the high-speed operation range while enabling high-efficiency operation in the low-speed operation range.

[Description of drive circuit 12]
A full-wave rectifier circuit 22 of a diode bridge is connected to a three-phase AC power supply 20 via a noise filter 21, and a capacitor 24 is connected to an output terminal 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 (referred to also as a first inverter or a master inverter) for controlling energization of one end of the phase windings Lu, Lv, Lw between the DC power supply 25 and one end of the phase windings Lu, Lv, Lw of the motor 1M. 30 are connected. An inverter (also referred to as a second inverter or a slave inverter) for controlling energization of the other ends of the phase windings Lu, Lv, Lw between the DC power supply 25 and the other ends of the phase windings Lu, Lv, Lw of the motor 1M. ) 40 is connected. A common power supply system in which the

inverters

30 and 40 are connected to a common DC power supply 25 is employed. Not limited to the common power supply system, a power supply insulation system in which the

inverters

30 and 40 are connected to different DC power supplies may be employed.

Inverter 30 is a U-phase series circuit in which switching elements such as

IGBTs

31 and 32 are connected in series, and an interconnection point of the

IGBTs

31 and 32 is connected to one end of phase winding Lu of open winding motor 1M, and

IGBTs

33 and 34 are connected in series. The

IGBTs

33 and 34 are connected in series to a V-phase series circuit in which one end of the phase winding Lv of the open winding motor 1M is connected to IGBTs 35 and 36, and the

IGBTs

35 and 36 are connected in an open winding. It includes a W-phase series circuit connected to one end of the phase winding Lw of the motor 1M, converts the DC voltage Vdc of the DC power supply 25 into a three-phase AC voltage of a predetermined frequency by switching of the IGBTs 31 to 36, and converts the three-phase AC voltage. Is supplied to one end of each of the phase windings Lu, Lv, Lw of the open winding motor 1M. Regeneration diodes (also referred to as free wheel diodes) 31a to 36a are connected in anti-parallel to the IGBTs 31 to 36, respectively.

The inverter 40 connects the

IGBTs

41 and 42 in series, and connects the

IGBTs

43 and 44 in series with the U-phase series circuit in which the interconnection point of the

IGBTs

41 and 42 is 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,

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. Including a W-phase series circuit connected to the other end of the winding Lw, the DC voltage Vdc of the DC power supply 25 is converted into a three-phase AC voltage of a predetermined frequency by switching of the IGBTs 41 to 46, and the three-phase AC voltage is To the other ends of the phase windings Lu, Lv, Lw. Regeneration diodes (also referred to as free wheel diodes) 41a to 46a are connected in anti-parallel to the IGBTs 41 to 46.

The inverter 30 houses a main circuit formed by connecting three sets of series circuits of two switching elements 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 normally open contact (referred to as a relay contact) 51a of a switch, for example, a relay 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. Between the other end of the phase winding Lv of the motor 1M and the other end of the phase winding Lw, a normally open contact (referred to as a relay contact) 52a of a switch, for example, a relay 52 is connected. The energization and de-energization of the

relays

51 and 52 are controlled by the motor controller 13 in synchronization with each other. When the

relay contacts

51a, 52a are closed, the other ends of the phase windings Lu, Lv, Lw are interconnected, and the phase windings Lu, Lv, Lw are in a star connection state. The interconnection point at the other end of the phase windings Lu, Lv, Lw is the neutral point of the star connection. When the

relay contacts

51a, 52a are opened, the phase windings Lu, Lv, Lw are disconnected (open state), and the phase windings Lu, Lv, Lw are electrically separated.

(4)

Current sensors

53, 53v, and 53w are arranged on each energizing line between the inverter 30 and the motor 1M, and detection signals from the

current sensors

53, 53v, and 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 includes a main control unit 60, a voltage detection unit 61, an inverter control unit 62, a relay drive unit 63, a

relay

51, 52 and the like. Voltage detector 61 detects output voltage Vdc of DC power supply 25. Relay drive section 63 energizes or deactivates

relays

51 and 52 in response to a command from main control section 60.

Inverter control unit 62 estimates the speed (rotation speed) ωest of motor 1M based on the detection results of

current sensors

53, 53v, 53w, and converts

inverters

30, 40 according to the difference between the estimated speed ωest and target speed ωref. , A current detection unit 71, a speed estimation calculation unit 72, an integration unit 73, a subtraction unit 74, a speed control unit 75, an Id control unit 76, and a subtraction, as shown in FIG.

Units

77 and 78, current control units 81 and 82, and a PWM signal generation unit 83.

The current detection unit 71 captures currents (motor currents) flowing through the phase windings Lu, Lv, Lw of the motor 1M from the outputs of the

current sensors

53, 53v, 53w, and a field component (d-axis component) Id of the captured current. And a torque component (q-axis component) Iq. The field component Id of the current is called a field component current Id, and the torque component Iq of the current is called a torque component current Iq. The field component current Id is a current converted to a field axis (d-axis) coordinate on the rotor axis, and is also referred to as a d-axis current or a reactive current. The torque component current Iq is a current converted to a torque axis (q axis) coordinate on the rotor shaft, and is also referred to as 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 integrator 73, the subtractor 74, and the main controller 60.

The speed estimation calculation unit 72 estimates the speed (rotor rotation speed) 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 integrator 73 and the main controller 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 the deviation ωerr is sent to the speed control unit 75.

The speed control unit 75 calculates a target value Iqref of the torque component current Iq by performing a proportional / integral control (PI control) on the deviation ωerr. The data of the target value Iqref is sent to the Id control unit 76. The Id control unit 76 calculates a 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. When the main control unit 60 instructs the main control unit 60 to execute the field weakening control for injecting the negative field component current “−Id” into the phase windings Lu, Lv, and Lw, the Id control unit 76 performs the control. Is added to the target value Idref obtained above. The subtracting unit 77 calculates a deviation ΔId between the target value Idref and the field component current Id. The subtraction unit 78 obtains a 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 controllers 81 and 82, respectively.

The 制御 current control unit 81 calculates a field component (d-axis component) Vd of the drive voltage to be supplied to the motor 1M by performing a proportional / integral control (PI control) calculation of the deviation ΔId. The field component voltage Vd is a voltage converted into a field axis (d-axis) coordinate on the rotor axis, and is also called a d-axis voltage or an invalid voltage. The current control unit 82 calculates a torque component (q-axis component) Vq of the drive voltage to be supplied to the motor 1M by performing a proportional / integral control (PI control) operation on the deviation ΔIq. The torque component voltage Vq is a voltage converted into a torque axis (q axis) coordinate on the rotor shaft, and is also referred to as 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 generator 83 and the main controller 60.

When the main control unit 60 sets the star connection mode, the PWM signal generation unit 83 converts the PWM signal (pulse width modulation signal) P1 for independently switching the inverter 30 into the field component voltage Vd and the torque component voltage. It is generated based on Vq, rotor position θest, and the like. When the main control unit 60 sets the open winding mode, the PWM signal generation unit 83 outputs the PWM signal P2 for switching the

inverters

30 and 40 in cooperation with each other to the field component voltage Vd and the torque component voltage. It is generated based on Vq, rotor position θest, and the like. The switching elements of the

inverters

30 and 40 are turned on and off according to the generated PWM signals P1 and P2. Data of the on / off duties Du1 and Du2 of these PWM signals P1 and P2 are sent to the main control unit 60.

The main control unit 60 is constituted by a microcomputer and its peripheral circuits. It controls switching of the

switches

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 instructs the set target speed ωref to the inverter control unit 62. In addition, the first control unit 60a determines that when the on / off duties Du1 and Du2 of the PWM signals P1 and P2 generated by the inverter control unit 62 reach the control upper limit and the motor speed cannot be increased, In order to further increase the motor speed, the controller 62 instructs the inverter control unit 62 to perform field weakening control in which a negative field component current “−Id” is applied to the phase windings Lu, Lv, Lw.

The second control unit 60b connects the phase windings Lu, Lv, and Lw in a star-shape by closing the

relay contacts

51a and 52a, and switches only the inverter 30 alone. The second control unit 60b controls the

relay contacts

51a and 52a. The open winding mode in which the phase windings Lu, Lv and Lw are disconnected (open state) by opening and the

inverters

30 and 40 are switched in cooperation with each other is stored in the estimated speed ωest of the inverter control unit 62 and the internal memory. 4 by referring to the mode selection condition of FIG.

The mode selection condition specifies a highly efficient star connection mode when the estimated speed ωest is in a low speed operation range less than the threshold ωest2 when the estimated speed ωest changes in the rising direction, and the estimated speed ωest is equal to or larger than the threshold ωest2. If it is in the high speed operation range, specify the open winding mode. When the estimated speed ωest changes in the descending direction when the estimated speed ωest is in the high speed operation range exceeding the threshold ωest1 (<ωest2), the mode selection condition specifies the open winding mode, and the estimated speed ωest If the vehicle is in the low-speed operation range below ωest1, specify the star connection mode.

When switching from the open winding mode to the star connection mode by the second control unit 60b, the third control unit 60c sets the on / off duty Du2 or the on / off duty Du2 of the switching of the open winding mode before the switching. When the corresponding voltage utilization factor X is equal to or less than a set value (for example, 50%), the switching from the open winding mode to the star connection mode by the second control unit 60b is immediately permitted (executed). Further, when the second control unit 60b switches from the open winding mode to the star connection mode by the second control unit 60b, the third control unit 60c switches ON / OFF duty Du2 of the switching of the open winding mode before switching or ON / OFF duty thereof. When the voltage utilization factor X corresponding to Du2 exceeds the set value, the target speed ωref is decreased to lower the on / off duty Du2 or the voltage utilization factor X to the set value or less. Then, the switching from the open winding mode to the star connection mode by the second control unit 60b is permitted (executed). Further, the third controller 60c cancels the decrease in the target speed ωref after the switching from the open winding mode to the star connection mode by the second controller 60b is completed.

Note that 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 among 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 the value is equal to or less than the 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 maximum rated output voltage of the

inverters

30 and 40 in accordance with the on / off duty Du2. Equation (1) below 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 referred to as S1, S2,.

[Star connection mode]
When an 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 alone. A star connection mode for switching is set (S2).

FIG. 6 shows a part of the current path formed in the star connection mode. First, the upstream IGBT 31 in the inverter 30 is turned on, and the

downstream IGBTs

34 and 36 repeat the on and off of the on / off duty Du1 while synchronizing with each other. As a result, as indicated by the dashed arrow, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lu through the IGBT 31, and the current passing through the phase winding Lu passes through the

relay contacts

51a and 52a to form a phase winding. The current flows through the lines Lv and Lw, and the current passing through the 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 in the inverter 30 is turned on, and the

IGBTs

32 and 36 on the downstream side repeat the on / off of the on / off duty Du1 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lv through the IGBT 33, and a 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 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 IGBT 35 on the upstream side in the inverter 30 is turned on, and the

IGBTs

32 and 34 on the downstream side repeat the on / off of the on / off duty Du1 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lw through the IGBT 35, and a 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 kept in a stopped state, that is, a state in which the switching operation is not performed. When the motor 1M is started in the star connection mode, the motor controller 13 determines whether the estimated speed ωest has increased to the threshold ωest2 (S4). While the estimated speed ωest is lower than the threshold ωest2 (NO in S4, NO in S5), if there is no operation stop command from the controller 10 (NO in S12), the motor controller 13 returns to S3, and the estimated speed ωest is reduced. The on / off duty Du1 of the switching of the inverter 30 is controlled so as to reach the target speed ωref (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 to reach the threshold ωest2 (high rotation speed region; YES in S4), that is, from the star connection mode to the open winding mode When switching to the required state is performed, the motor controller 13 sets the other ends of the phase windings Lu, Lv, Lw to the non-connected (open: open) state by opening the relay contacts 51a, 52a. , 40 are set in an open winding mode for switching in cooperation with each other (S6). If there is no operation stop command from the controller 10 (NO in S12), the motor controller 13 shifts to S3 and turns on and off duty of the switching of the

inverters

30 and 40 so that the estimated speed ωest becomes the target speed ωref. Du2 is controlled (S3).

(2) A part of the current path in the open winding mode is shown by a broken line in FIG. First, the upstream IGBT 31 of the inverter 30 is turned on, the downstream IGBT 42 of the inverter 40 repeats the on / off of the on / off duty Du2, and the

upstream IGBTs

43 and 45 of the inverter 40 are both turned on. The on / off duty Du2 is repeatedly turned on and off while the

downstream IGBTs

34 and 36 in 30 are synchronized with each other. As a result, as indicated by a broken line arrow, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lu through the IGBT 31, and the current passing through the phase winding Lu passes through the IGBT 42 to the negative side of the DC power supply 25. The current flows from the positive terminal of the DC power supply 25 to the phase windings Lv and Lw through the

IGBTs

43 and 45, 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 IGBT 33 of the inverter 30 is turned on, the downstream IGBT 44 of the inverter 40 repeats the on / off of the on / off duty Du2, and the

upstream IGBTs

41 and 45 of the inverter 40 are both turned on. The

IGBTs

32 and 36 on the downstream side of the inverter 30 repeat the on / off of the on / off duty Du2 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lv through the IGBT 33, the current passing through the phase winding Lv flows to the negative terminal of the DC power supply 25 through the IGBT 44, and the DC power supply Current flows from the positive terminal of the DC power supply 25 to the phase windings Lu and Lw through the

IGBTs

41 and 45, and the current passing through the phase windings Lu and Lw flows to the negative terminal of the DC power supply 25 through the

IGBTs

32 and 36. Next, the upstream IGBT 35 of the inverter 30 is turned on, the downstream IGBT 46 of the inverter 40 repeats the on / off of the on / off duty Du2, and the

upstream IGBTs

41 and 43 of the inverter 40 are both turned on. The

IGBTs

32 and 34 on the downstream side of the inverter 30 repeat the on / off of the on / off duty Du2 while synchronizing with each other. As a result, a current flows from the positive terminal of the DC power supply 25 to the phase winding Lw through the IGBT 35, the current passing through the phase winding Lw flows to the negative terminal of the DC power supply 25 through the IGBT 46, and the DC power supply A current flows from the positive terminal of the DC power supply 25 to the phase windings Lu and Lv through the

IGBTs

41 and 43, and a current passing through the phase windings Lu and Lv flows to the negative terminal of the DC power supply 25 through the

IGBTs

32 and 34. The rotor of the motor 1M rotates by sequentially switching these three patterns of current paths.

(4) By setting the open winding mode, a high-level voltage approximately 1.7 times that in the star connection mode is applied to the phase windings Lu, Lv, and Lw, and the motor 1M can rotate at 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]
During the open winding mode, when the estimated speed ωest decreases with the decrease of the target speed ωref and reaches the threshold ωest1 (low rotation speed region; NO in S4, YES in S5), that is, from the open winding mode to the star shape When switching to the connection mode is necessary, the motor controller 13 monitors whether the on / off duty Du2 is equal to or less than the set value of 50% (S7).

When the on / off duty Du2 in 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 windings Lu, Lv, Lw in the switched star connection mode. In order to apply the voltage, it is necessary to set an on / off duty Du1 of 80% (= 40% × 2) in the star connection mode after switching. The on / off duty Du1 of 80% can be set in the star connection mode.

Then, when the on / off duty Du2 in the open winding mode is 50% or less (YES in S7), the motor controller 13 connects the phase windings Lu, Lv, Lw by star connection by closing the

relay contacts

51a, 52a. Then, the star connection mode in which the inverter 30 is independently switched is immediately set (S9). After the switching from the open winding mode to the star connection mode is completed, the motor controller 13 checks whether or not there is a process of lowering the target speed ωref in S8 described later (S10). At this time, since there is no process of lowering 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).

If there is no operation stop command (NO in S12), the motor controller 13 proceeds to S3 and controls the on / off duty Du1 of the switching 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 is more than 50%, for example, 55%, the same level voltage as in the open winding mode in the star connection mode after switching is applied to the phase windings Lu, Lv,. In order to apply the voltage to Lw, it is necessary to set an on / off duty Du1 of 110% (= 55% × 2) in the star connection mode after switching. Of course, the on / off duty Du1 exceeding 100% cannot be set.

Therefore, when the on / off duty Du2 in the open winding mode exceeds 50% as in the case of the above 55% (NO in S7), the motor controller 13 reduces the target speed ωref by a predetermined value (S8). . Due to the decrease in the target speed ωref, the on / off duty Du2 in the open winding mode changes in a decreasing direction. Subsequently, the motor controller 13 returns to S7 and monitors whether the on / off duty Du2 has become 50% or less (S7).

If the on / off duty Du2 still exceeds 50% despite the reduction of the target speed ωref (NO in S7), the motor controller 13 further reduces the target speed ωref by a predetermined value (S8). . Then, the motor controller 13 returns to S7, and monitors again whether the on / off duty Du2 is 50% or less (S7). The motor controller 13 repeats the processing of S7 and S8 until the on / off duty Du2 decreases to 50% or less. Note that the decrease in the target speed ωref in S8 is a temporary measure, and the original target speed ωref is based on a command from the outside and exists as it is.

When the on / off duty Du2 of the open winding mode is reduced to 50% or less, for example, 48%, the same level voltage as in the open winding mode is applied to the phase windings Lu, Lv, Lw in the switched star connection mode. , It is necessary to set an on / off duty Du1 of 96% (= 48% × 2) in the star connection mode after switching. The 96% on / off duty Du1 can be set in the 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 inverter 30 is independently switched with the on / off duty Du1 of the power supply to set the star connection mode (S9). After the switching from the open winding mode to the star connection mode is completed in this way, the motor controller 13 checks whether there is a process of decreasing the target speed ωref in S8 (S10). At this point, since there is a process of decreasing the target speed ωref (YES in S10), the motor controller 13 cancels the decrease in 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).

If there is no operation stop command from the controller 10 (NO in S12), the motor controller 13 proceeds to S3, and changes the on / off duty Du1 of the switching of the inverter 30 so that the estimated speed ωest becomes the original target speed ωref. Control (S3), if the target speed ωref has been reduced before, the speed is increased to return to the original speed. When receiving the operation stop command 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 factor X) of the open winding mode exceeds the set value, the on / off duty Du2 (or voltage utilization factor X) is reduced to a set value or less, and after this decrease, switching from the open winding mode to the star connection mode is performed. However, it is possible to reliably shift from the open winding mode to the star connection mode.

When switching from the open winding mode to the star connection mode and when switching from the star connection mode to the open winding mode, the motor controller 13 switches both of the

inverters

30 and 40 so as to cooperate and synchronize. Control. Thus, the 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 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 switches the

relay contacts

51a and 52a. Open and close. Since the

relay contacts

51a and 52a open and close in a state where no current flows through the

relay contacts

51a and 52a, it is possible to prevent the occurrence of sparks and the like at the

relay contacts

51a and 52a, and to prevent a failure such as welding of the

relay contacts

51a and 52a. Can be avoided.

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

[2] A second embodiment will be described.

制御 The second embodiment is different from the first embodiment in control and operation when switching from the open winding mode to the star connection mode. Others are the same as the first embodiment.

When switching from the open winding mode to the star connection mode by the second control unit 60b, the third control unit 60c of the main control unit 60 controls the on / off duty Du2 (or the voltage) of the switching in the open winding mode before the switching. When the utilization rate X) is equal to or less than the set value (for example, 50%), the switching from the open winding mode to the star connection mode by the second control unit 60b is immediately permitted (executed). Further, when switching from the open winding mode to the star connection mode by the second control unit 60b, the third control unit 60c causes the on / off duty Du2 of the switching in the open winding mode before the switching to exceed the set value. In this case, the on / off duty Du2 is reduced to the set value or less by executing the field weakening control in which a negative field component current is applied to the respective phase windings, and thereafter, the open winding by the second control unit 60b is performed. The switch from the line mode to the star connection mode is permitted (executed). Further, the third controller 60c cancels the decrease in the target speed ωref after the switching from the open winding mode to the star connection mode by the second controller 60b is completed.

Normally, the field-weakening control further increases the rotation speed when the motor rotates at a high speed and the on / off duty is 100%, and the induced voltage of the winding increases and the rotation speed cannot be further increased. In the present embodiment, the control 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 'in place of the processes of S8, S10, and S11 in the flowchart of FIG.

That is, the motor controller 13 determines that the on / off duty Du2 of the open winding mode exceeds the set value of 50% in a situation where switching from the open winding mode to the star connection mode is required (S7). NO), field weakening control of injecting a negative field component current "-ΔId" of a predetermined magnitude into the phase windings Lu, Lv, Lw is performed (S8 '). Due to this field weakening control, the on / off duty Du2 of the open winding mode is reduced.

After the injection of the negative field component current “−ΔId”, the motor controller 13 returns to S7 and monitors again whether or not the on / off duty Du2 has reached 50% or less (S7).

If the on / off duty Du2 still exceeds 50% despite the injection of the negative field component current “−ΔId” (NO in S7), the motor controller 13 further reduces the predetermined magnitude of negative current. Is further injected into the phase windings Lu, Lv, Lw (S8 '). As a result, the negative field component current becomes twice “−2 · ΔId”.

As a result, when the motor 1M is rotating at the same speed, the on / off duty Du2 further decreases. Then, the motor controller 13 returns to S7, and monitors again whether the on / off duty Du2 is 50% or less (S7). Until the on / off duty Du2 decreases to 50% or less, the processes of S7 and S8 'are repeated, and the negative field component current is increased.

When the on / off duty Du2 has decreased to 50% or less (YES in S7), the motor controller 13 closes the

relay contacts

51a and 52a and sets the star connection mode in place of the open winding mode up to that time. (S9). Then, the motor controller 13 checks whether or not there is the field weakening control in S8 '(S10'). At this point, since the field weakening control is in operation (YES in S10 '), the motor controller 13 thereafter shifts to the field weakening control in the star connection mode, and the field weakening amount (negative field component current " −ΔId ″) (S11 ′), thereby appropriately controlling the speed of the motor 1M. Thereafter, 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 the voltage utilization factor X) of the open winding mode exceeds the set value, the negative field is set. The on / off duty Du2 (or the voltage utilization factor X) is reduced by executing the field weakening control injecting the component current “−Id”, and after the on / off duty Du2 has dropped to 50% or less, the star is switched from the open winding mode. Since the switching to the 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 increases.

Other configurations and controls are the same as those of the first embodiment.

[Modification]
In 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 a range of 50% or less. It is possible.

In each of the above embodiments, as the mode selection condition, switching from the open winding mode to the star connection mode is performed according to the estimated speed ωest, but the mode is switched from the open winding mode to the star connection mode according to the target speed ωref. Switching to the connection mode may be performed. The threshold value at which the switching from the open winding mode to the star connection mode may be variably set according to the state of the refrigeration cycle and the motor current value. In addition, switching from the open winding mode to the star connection mode may be performed 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 the voltage utilization rate X) is reduced by the operation of decreasing the target speed ωref. However, the on / off duty of the PWM signal P2 generated by the inverter control unit 62 is reduced. Du2 (or voltage utilization factor X) may be configured to directly decrease the operation.

In the above embodiments, the case where the switches are the

relay contacts

51a and 52a has been described as an example. However, a semiconductor switch can be used as the switches.

In the above embodiments, the open winding motor used as the motor for driving the compressor has been described as an example. However, the present invention can be similarly applied to an open winding motor used for other purposes.

In each of the above embodiments, the case where the three-phase inverter device including six switching elements is used as the inverter 30 and the three-phase inverter device including six switching elements is used as the inverter 40 has been described as an example. Inverter 30 and Inverter 40 may be configured using three single-phase inverter devices.

Further, the decrease 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 can be reduced simultaneously with decreasing the rotation speed of the motor 1M as in the first embodiment. It may be executed by adding the field weakening control in the second embodiment.

Otherwise, the above-described embodiments and modified examples have been presented as examples, and are not intended to limit the scope of the invention. Each of the new embodiments and modifications can be implemented in other various forms, and various omissions, rewrites, and changes can be made without departing from the spirit of the invention. In these embodiments and modifications, the scope of the invention is included in the gist, and is included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 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: three-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

A motor drive device for a motor having a plurality of phase windings that are not connected to each other,
A first inverter including a plurality of switching elements, and controlling the energization of one end of each phase winding of the motor by the switching elements;
A second inverter including a plurality of switching elements, and controlling the energization of the other end of each phase winding of the motor by the switching elements;
A switch connected between the other ends of the phase windings,
The first connection is switched to the star connection mode by switching the first inverter by star-connecting the phase windings by closing the switch, and the first phase winding is disconnected by opening the switch. A motor controller having an open winding mode for switching an inverter and the second inverter;
With
The motor controller comprises:
When switching from the open winding mode to the star connection mode, the ON / OFF duty of the switching of the open winding mode before switching or the voltage utilization rate corresponding to the ON / OFF duty exceeds a set value. A motor drive device that reduces the on / off duty or the voltage utilization rate to a value equal to or less than the set value, and after the decrease, switches from the open winding mode to the star connection mode.
The motor controller comprises:
When switching from the open winding mode to the star connection mode, when the on / off duty of switching of the open winding mode before switching or the voltage utilization rate corresponding to the on / off duty is equal to or less than the set value, The motor drive device according to claim 1, wherein switching from the open winding mode to the star connection mode is performed immediately.
The motor controller comprises:
A star connection mode in which the phase windings are star-connected by closing the switch, the first inverter is switched, and the on / off duty of the switching is controlled so that the speed of the motor becomes a target speed; And opening the switch to disconnect the phase windings to switch the first inverter and the second inverter, and control the on / off duty of the switching so that the speed of the motor becomes the target speed. The motor driving device according to claim 1, wherein the open winding mode to be set is selectively set.
The motor controller comprises:
When switching from the open winding mode to the star connection mode, the ON / OFF duty of switching in the open winding mode before switching or the voltage utilization rate corresponding to the ON / OFF duty exceeds the set value. In this case, the on / off duty or the voltage utilization rate of the motor is reduced below the set value by reducing the speed of the motor, and thereafter, the switching from the open winding mode to the star connection mode is performed. The motor drive device according to claim 1, wherein
The controller is
When switching from the open winding mode to the star connection mode, the switching on / off duty of the open winding mode before switching or the voltage utilization rate corresponding to the on / off duty exceeds the set value. In the case, the on / off duty or the voltage utilization rate is reduced to the 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. The motor drive device according to claim 1, wherein switching to the star connection mode is performed.
The controller is
The star winding mode is set in a low-speed operation range of the motor, and the open winding mode is set in a high-speed operation range of the motor. A motor drive device according to claim 1.
A refrigeration cycle device comprising the motor drive device according to claim 1,
A compressor that has the open winding motor as a driving motor, and that sucks and compresses and discharges refrigerant.
The compressor, a four-way valve, a condenser, a decompressor, and an 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 refrigerant. A heat pump refrigeration cycle that returns to the suction side of the machine,
A refrigeration cycle device comprising: