CN111264026B - Motor driving device, refrigeration cycle device, air conditioner, water heater, and refrigerator - Google Patents
Motor driving device, refrigeration cycle device, air conditioner, water heater, and refrigerator Download PDFInfo
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- CN111264026B CN111264026B CN201780096150.9A CN201780096150A CN111264026B CN 111264026 B CN111264026 B CN 111264026B CN 201780096150 A CN201780096150 A CN 201780096150A CN 111264026 B CN111264026 B CN 111264026B
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
- H02P27/04—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage
- H02P27/06—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using variable-frequency supply voltage, e.g. inverter or converter supply voltage using DC to AC converters or inverters
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- Power Engineering (AREA)
- Control Of Ac Motors In General (AREA)
Abstract
The motor drive device (2) has a connection switching device (60), an inverter (30), and a control device (100), wherein the connection switching device (60) performs switching operations of the switches (61-63) during rotation operations of the motor (7) to switch connection states of windings (71-73) of the motor (7), the inverter (30) applies alternating voltage to the windings (71-73) via the switches (61-63), and back electromotive force is applied to the windings (71-73) of the motor (7) during self-rotation operations of the switches (61-63), and the control device (100) controls the inverter (30) and the connection switching device (60) to control rotation operations of the motor (7), and performs switching operations of the switches (61-63) during current control periods in which the 1 st effective value of alternating current flowing through the windings (71-73) is closer to zero than the 2 nd effective value of alternating current flowing through the windings (71-73) before switching operations of the switches (61-63).
Description
Technical Field
The present invention relates to a motor drive device, a refrigeration cycle device provided with the motor drive device, and an air conditioner, a water heater, and a refrigerator provided with the refrigeration cycle device.
Background
Conventionally, there is known a technique of switching a state of connection of stator windings (hereinafter also referred to as "windings") of an electric motor to any one of star connection (Y-connection) and delta connection (delta connection), in which a current is applied to a standby load of a drive circuit, and the switching is performed in a state in which the current is applied (for example, refer to patent document 1).
In addition, there is known a technique of operating a switching relay to select a Y-type connection when the frequency of an ac voltage applied to a winding of a motor is lower than a predetermined frequency, and operating a switching relay to select a delta-type connection when the frequency is equal to or higher than the predetermined frequency (for example, refer to patent document 2).
Prior art literature
Patent literature
Patent document 1: japanese patent laid-open publication 2016-86587 (for example, as set forth in claim 1, FIGS. 2 to 9)
Patent document 2: japanese patent laid-open No. 2008-228513 (for example, claims 1, 15, and 20)
Disclosure of Invention
Problems to be solved by the invention
In the technique described in patent document 1, the connection state of the winding is switched in a state in which current is supplied to the backup load. However, the following problems exist: in an environment where a large current flows in the motor, it is necessary to increase the power capacity of the backup load, thereby not only increasing the size of the apparatus but also generating heat in the backup load.
In the technique described in patent document 2, a mechanical relay or a semiconductor relay is used as a wire switching relay for switching the wire connection state of the winding. However, when the contacts of the mechanical relay are switched during operation of the inverter, arc discharge may occur between the contacts, and the contacts may be welded to cause a failure. In addition, when the semiconductor relay is operated during the operation of the inverter, a wiring state in which the plurality of semiconductor relays are not Y-type-connected or delta-type-connected may be caused by a difference in operation timings, and an excessive current may flow in the semiconductor relay to cause a failure.
In addition, when the switching operation of the wire switching relay is performed after stopping the rotation operation of the motor in order to avoid the failure of the wire switching relay, there are problems as follows: if the time required for the device using the motor (for example, several minutes before the state of the refrigerant stabilizes in the case of the compressor) does not elapse, the motor cannot be restarted.
The present invention has been made in view of the above circumstances, and an object thereof is to provide a motor drive device capable of performing switching operation of a switch for switching connection states of windings of a motor without stopping rotation operation of the motor, and being less likely to cause a failure due to switching of connection states, and a device provided with the motor drive device.
Means for solving the problems
The motor driving device of the present invention is a motor driving device for driving a permanent magnet synchronous motor, and includes a connection switching device including a switcher for switching a connection state of windings of the motor between a Y-type coupling and a delta-type coupling by performing a switching operation of the switcher during a rotation operation of the motor, an inverter for applying an ac voltage to the windings via the switcher, and applying a back electromotive force to the windings of the motor during a self-rotation operation of the switcher (japanese: counter-voltage), the current detection means detecting a current supplied to the inverter, the control means controlling the inverter based on the current detected by the current detection means, thereby controlling a rotation operation of the motor, the inverter being controlled such that a current of a protection level or less flows in the motor, the protection level being a set current value switched in accordance with the connection state, the switching operation of the switcher being performed during a current control period in which a 1 st effective value of an alternating current flowing in the winding is made to be closer to zero than a 2 nd effective value of an alternating current flowing in the winding before the switching operation of the switcher, and an alternating voltage is applied to the motor such that a rotation speed of the motor is not zero and counter electromotive force generated by the rotation operation of the motor is offset, the 1 st protection level being the protection level when the connection state is the Y-type connection, the 2 nd protection level being the protection level when the connection state is the delta-type connection, the 1 st protection level is set lower than the 2 nd protection level, and the protection level at the time of starting control that is closer to zero than the 2 nd effective value of the alternating current flowing through the winding or the protection level during the period from the start of control that is closer to zero than the 2 nd effective value of the alternating current flowing through the winding until the completion of switching of the connection state is set to the 1 st protection level.
Effects of the invention
According to the present invention, since the switching operation of the switching device is performed during the current control period in which the effective value of the ac current flowing through the winding is controlled to be close to zero, the failure of the connection switching device is less likely to occur, and the life of the motor driving device can be prolonged.
In addition, according to the present invention, the connection state of the winding is switched during the current control period in which the rotation operation of the motor is not stopped. Therefore, it is not necessary to temporarily stop the rotation operation of the motor and restart the motor after that in order to switch the connection state of the windings.
Drawings
Fig. 1 is a schematic diagram showing a configuration example of an air conditioner (including a refrigeration cycle apparatus) according to an embodiment.
Fig. 2 is a schematic diagram showing a configuration example of a water heater (including a refrigeration cycle apparatus) according to the embodiment.
Fig. 3 is a schematic diagram showing a configuration example of a refrigerator (including a refrigeration cycle apparatus) according to the embodiment.
Fig. 4 is a schematic wiring diagram showing a motor driving device according to embodiment 1 of the present invention.
Fig. 5 is a diagram showing a structure of the inverter of fig. 4.
Fig. 6 is a wiring diagram showing the windings and connection switching device of the motor of fig. 1 in detail.
Fig. 7 is a wiring diagram showing a detailed structure of a switcher of the connection switching apparatus of fig. 4.
Fig. 8 (a) and (b) are diagrams conceptually showing windings in different wiring states of the motor.
Fig. 9 is a functional block diagram showing an example of a control device used in embodiment 1.
Fig. 10 is a diagram showing the voltage command calculation unit of fig. 9 in detail.
Fig. 11 is a waveform diagram showing the operation of the motor drive device according to embodiment 1.
Fig. 12 is a wiring diagram showing windings and connection switching devices of the motor according to embodiment 2 of the present invention.
Fig. 13 is a circuit diagram showing a configuration example in which a MOS transistor is used for the switch of the connection switching device of fig. 12.
Fig. 14 is a diagram showing an example of on and off states of the MOS transistor of the switch of fig. 13 in a table format.
Fig. 15 is a wiring diagram showing windings and a connection switching device of the motor according to embodiment 3 of the present invention.
Detailed Description
Hereinafter, a motor driving device, a refrigeration cycle device as a refrigeration cycle application apparatus provided with the motor driving device, and an air conditioner, a water heater, and a refrigerator provided with the refrigeration cycle device according to embodiments of the present invention will be described with reference to the drawings. The embodiments described below are merely examples, and the motor driving device and each device provided with the motor driving device can be variously modified within the scope of the present invention. In the following description, the same reference numerals are given to the same or similar functions.
Fig. 1 is a schematic diagram showing a configuration example of an air conditioner (including a refrigeration cycle apparatus 900) according to an embodiment. As shown in fig. 1, the refrigeration cycle apparatus 900 can perform a heating operation or a cooling operation by switching operation of the four-way valve 902.
In the heating operation, as shown by solid arrows, the refrigerant is pressurized by the compressor 904 and sent out, and returns to the compressor 904 through the four-way valve 902, the indoor heat exchanger 906, the expansion valve 908, the outdoor heat exchanger 910, and the four-way valve 902. In the cooling operation, as indicated by the broken-line arrows, the refrigerant is pressurized by the compressor 904 and sent out, and returns to the compressor 904 through the four-way valve 902, the outdoor heat exchanger 910, the expansion valve 908, the indoor heat exchanger 906, and the four-way valve 902.
During heating operation, the heat exchanger 906 functions as a condenser to emit heat (heat is generated in the room), and the heat exchanger 910 functions as an evaporator to absorb heat. During cooling operation, heat exchanger 910 functions as a condenser to emit heat, and heat exchanger 906 functions as an evaporator to absorb heat (cool the room). The expansion valve 908 decompresses and expands the refrigerant. The compressor 904 is driven by a motor 7 that can be controlled in a variable speed by the motor driving device 2.
Fig. 2 is a schematic diagram showing a configuration example of a heat pump water heater (including a refrigeration cycle apparatus 900 a) according to the embodiment. As shown in fig. 2, in the refrigeration cycle apparatus 900a, the heat exchanger 906 functions as a condenser to emit heat (heat water), and the heat exchanger 910 functions as an evaporator to absorb heat. The compressor 904 is driven by a motor 7 that can be controlled in a variable speed by the motor driving device 2.
Fig. 3 is a schematic diagram showing a configuration example of a refrigerator (including a refrigeration cycle apparatus 900 b) according to the embodiment. As shown in fig. 3, in the refrigeration cycle apparatus 900b, the heat exchanger 910 functions as a condenser to emit heat, and the heat exchanger 906 functions as an evaporator to absorb heat (cool the inside of the refrigerator). The compressor 904 is driven by a motor 7 that can be controlled in a variable speed by the motor driving device 2.
Embodiment 1.
1-1 summary of embodiment 1
Fig. 4 is a schematic wiring diagram showing the motor driving device 2 according to embodiment 1 of the present invention together with the motor 7 and the ac power supply 4. The motor driving device 2 is for driving the motor 7. As shown in fig. 4, the motor drive device 2 includes an inverter 30, a connection switching device 60, and a control device 100. The motor drive device 2 may include ac power input terminals 2a and 2b, a reactor 8, a rectifier circuit 10, a capacitor 20, a control power generation circuit 80, a bus current detection unit 85, and an electric quantity detection unit 90.
The connection switching device 60 has switches (switching circuits) 61 to 63, and switches the connection states (connection states) of the windings 71 to 73 of the motor 7 by performing switching operations of the switches 61 to 63 during rotation operations of the motor 7. The inverter 30 applies an ac voltage to the windings 71 to 73 via the switches 61 to 63, and applies a back electromotive force to the windings 71 to 73 of the motor 7 in the self-rotation operation via the switches 61 to 63.
The control device 100 controls the rotation of the motor 7 by controlling the inverter 30. In addition, the control device 100 causes the connection switching device 60 to perform switching of the connection state of the windings. In embodiment 1, the control device 100 performs the switching operation of the switches 61 to 63 in a current control period Pc (also referred to as "zero current control period") in which the value (1 st effective value) of the alternating current flowing through the windings 71 to 73 is made to be closer to zero than the value (2 nd effective value) of the alternating current flowing through the windings before the switching operation of the switches 61 to 63.
In addition, in the present application, the connection state of the winding includes both the wiring state of the winding (for example, Y-type bond and delta-type bond) and the number of turns of the winding. The switching of the number of turns of the winding is described in embodiment 3. In addition, when the switches 61 to 63 are configured by mechanical relays, the current control period Pc can be set to several hundred milliseconds or less. When the switches 61 to 63 are constituted by semiconductor switches, the current control period Pc can be set to several milliseconds or less. In addition, when the motor 7 is used for a compressor of a refrigeration cycle apparatus such as an air conditioner, a heat pump type water heater, or a refrigerator, the current control period Pc can be set in a range of several milliseconds to 1 second.
1-2 Structure of embodiment 1
The control device 100 is constituted by a microcomputer (micro computer) or DSP (Digital Signal Processor) or the like, and the microcomputer includes, for example, a memory as a storage device storing control information as a software program and a CPU (Central Processing Unit ) as an information processing device executing the program. The control device 100 may be configured by dedicated hardware (e.g., a processing circuit). The following describes a case where the control device 100 is constituted by a microcomputer.
The ac power input terminals 2a and 2b are connected to an external ac power source 4. Ac voltage is applied from the ac power supply 4 to the ac power supply input terminals 2a and 2 b. The applied voltage has an amplitude (effective value) of 100V or 200V, for example, and a frequency of 50Hz or 60Hz, for example.
The rectifier circuit 10 receives ac power from the ac power supply 4 via the input terminals 2a and 2b and the reactor 8, and rectifies the ac power to generate a dc voltage. The rectifier circuit 10 is a full-wave rectifier circuit formed by bridging rectifier elements 11 to 14 such as diodes.
The capacitor 20 smoothes the dc voltage generated by the rectifier circuit 10 to output a dc voltage V20.
Fig. 5 is a diagram showing a structure of inverter 30 in fig. 4. As shown in fig. 5, the inverter 30 has an inverter main circuit 310 and a driving circuit 350. An input terminal of the inverter main circuit 310 is connected to an electrode of the capacitor 20. The line connecting the output of the rectifier circuit 10 and the electrode of the capacitor 20 and the input terminal of the inverter main circuit 310 is referred to as a dc bus.
The inverter 30 is controlled by the control device 100 to turn on and off the switching elements 311 to 316 of the 6 branches of the inverter main circuit 310. Inverter 30 generates a three-phase ac current of variable frequency and variable voltage by the on and off operation, and supplies the three-phase ac current to motor 7. The rectifying elements 321 to 326 for the current are connected in parallel with the switching elements 311 to 316, respectively.
The motor 7 is a three-phase permanent magnet synchronous motor, and the ends of the stator windings (hereinafter also referred to as "windings") are led out of the motor 7, so that switching to either star connection (Y connection) or delta connection (delta connection) can be performed. The switching is performed by the connection switching device 60. In addition, in the case where the Y-type connection is referred to as the 1 st wiring, the Δ -type connection is referred to as the 2 nd wiring, and in the case where the Δ -type connection is referred to as the 1 st wiring, the Y-type connection is referred to as the 2 nd wiring. The connection state of the windings may be 3 or more.
Fig. 6 is a wiring diagram showing the stator winding of the motor 7 and the connection switching device 60 in more detail. As shown in fig. 6, the 1 st ends 71a, 72a, 73a of the 3-phase windings 71, 72, 73 of the U-phase, V-phase, and W-phase of the motor 7 are connected to external terminals 71c, 72c, 73c, respectively. The 2 nd ends 71b, 72b, 73b of the U-, V-, and W-phase windings 71, 72, 73 of the motor 7 are connected to external terminals 71d, 72d, 73d, respectively. In this way, the motor 7 can be connected to the connection switching device 60. The output lines 331, 332, 333 of the U-phase, V-phase, and W-phase of the inverter 30 are connected to the external terminals 71c, 72c, 73 c.
In the illustrated example, the connection switching device 60 is constituted by switches 61 to 63. As the switches 61, 62, 63, electromagnetic contactors in which contacts are opened and closed electromagnetically are used. Such electromagnetic contactors include devices called relays, contactors (contactors), and the like.
Fig. 7 is a wiring diagram showing a configuration example of the switches 61 to 63. The switches 61 to 63 are configured to take different connection states when current is applied to the exciting coils 611, 621, 631 and when current is not applied thereto, as shown in fig. 7, for example. The exciting coils 611, 621, 631 are connected to receive the switching power supply voltage V60 via the semiconductor switch 604. The semiconductor switch 604 is controlled to be opened and closed according to the switching control signal Sc output from the control device 100. In addition, when the supply of current from the microcomputer included in the control device 100 is sufficiently ensured, the microcomputer may directly operate to apply current to the exciting coil.
The common contact 61c of the switch 61 is connected to the external terminal 71d via a lead 61 e. The normally closed contact 61b is connected to the neutral point node 64, and the normally open contact 61a is connected to the V-phase output line 332 of the inverter 30.
The common contact 62c of the switch 62 is connected to the external terminal 72d via a lead 62 e. Normally closed contact 62b is connected to neutral node 64, and normally open contact 62a is connected to output line 333 of the W phase of inverter 30.
The common contact 63c of the switch 63 is connected to the external terminal 73d via a lead 63 e. Normally closed contact 63b is connected to neutral node 64, and normally open contact 63a is connected to output line 331 of the U-phase of inverter 30.
When no current flows in the exciting coils 611, 621, 631, the switches 61, 62, 63 are switched to the normally closed contact side, that is, the common contacts 61c, 62c, 63c are connected to the normally closed contacts 61b, 62b, 63b, as shown in fig. 7. In this state, the motor 7 is in a Y-coupled state.
When current flows in the exciting coils 611, 621, 631, the switches 61, 62, 63 are switched to the normally open contact side, that is, the common contacts 61c, 62c, 63c are connected to the normally open contacts 61a, 62a, 63a, contrary to the illustration. In this state, the motor 7 is in a delta-coupled state.
Here, the advantage of using a structure that can be switched to either of the Y-type coupling and the delta-type coupling as the motor 7 will be described with reference to fig. 8 (a) and (b). Fig. 8 (a) conceptually shows the wiring state of the winding when the Y-type connection is made, and fig. 8 (b) conceptually shows the wiring state of the winding when the delta-type connection is made.
The line-to-line voltage at the time of Y-type connection is set as V Y Let the current flowing into the winding be I Y The line-to-line voltage at the delta connection is set as V Δ Let the current flowing into the winding be I Δ When voltages applied to windings of respective phases are equalized to each other, there is a relationship of the following formulas (1) and (2).
Voltage V at Y-junction Y Current I Y And voltage V at delta connection Δ Current I Δ When the relationships of the formulas (1) and (2) are given, the electric power supplied to the motor at the time of Y-coupling and the electric power supplied to the motor at the time of Δ -coupling are equal to each other. That is, when the electric power supplied to the motors are equal to each other, the current at the time of delta-type coupling is large, and the voltage required for driving is largeLower.
The wiring state is selected in consideration of the above properties depending on the load condition or the like. For example, it is considered to perform low-speed operation with Y-type coupling at low load and high-speed operation with delta-type coupling at high load. By this arrangement, the efficiency at the time of low load is improved, and the high output at the time of high load can be realized.
In this regard, the case of the motor for driving the compressor of the air conditioner will be described in further detail. As the motor 7 for driving the compressor of the air conditioner, a synchronous motor having permanent magnets in a rotor is widely used in response to a request for energy saving. In recent air conditioners, when the difference between the room temperature and the set temperature is large, the room temperature is brought closer to the set temperature relatively quickly by the high-speed operation in which the motor 7 is rotated at a high speed, and when the room temperature and the set temperature are closer to each other, the room temperature is maintained by the low-speed operation in which the motor 7 is rotated at a low speed. In the case of such control, the time of the low-speed operation is large in proportion to the total operation time.
In the case of using a synchronous motor, as the rotation speed increases, the counter potential increases, and the voltage value required for driving increases. As described above, the counter potential is higher in the Y-type junction than in the delta-type junction.
In order to suppress the back electromotive force at high speed, it is considered to reduce the magnetic force of the permanent magnet or to reduce the number of turns of the stator winding. However, in that case, since the current for obtaining the same output torque increases, the current flowing through the motor 7 and the inverter 30 increases, and the efficiency decreases.
Thus, it is considered to switch the wiring state depending on the rotation speed. For example, when operation at a high speed is required, the connection state is a delta connection state. By providing this, the voltage required for driving (compared with Y-type coupling) can be made to beTherefore, it is not necessary to reduce the number of turns of the winding, nor to use the flux weakening control.
On the other hand, when the motor rotates at a low speed, the motor is in a Y-shaped connection state, and the current value is set to be smaller than the delta-shaped connectionFurther, the winding can be designed to be suitable for driving at a low speed in the Y-junction state, and the current value can be reduced as compared with the case where Y-junction is used over the entire speed range. As a result, the loss of the inverter 30 can be reduced, and the efficiency can be improved.
As described above, it is meaningful to switch the wiring state according to the load condition, and the connection switching device 60 is provided to perform such switching.
The bus current detection section 85 shown in fig. 4 detects a bus current, that is, a direct current Idc input to the inverter 30. The bus current detecting unit 85 includes a shunt resistor inserted into the dc bus, and supplies an analog signal indicating the detection result to the control device 100. This signal (detection signal) is converted into a digital signal by an a/D (Analog to Digital) conversion unit (not shown) in the control device 100, and is used for internal processing of the control device 100.
As described above, the control device 100 controls the switching of the connection state by the connection switching device 60, and controls the operation of the inverter 30. In order to control the inverter 30, the control device 100 generates PWM (Pulse Width Modulation ) signals Sm1 to Sm6 and supplies the PWM signals Sm1 to Sm6 to the inverter 30.
As shown in fig. 5, inverter 30 includes a driving circuit 350 in addition to an inverter main circuit 310, and driving circuit 350 generates driving signals Sr1 to Sr6 based on the PWM signal. The drive circuit 350 controls the on and off of the switching elements 311 to 316 based on the drive signals Sr1 to Sr6, thereby applying a variable-frequency and variable-voltage three-phase ac voltage to the motor 7.
The PWM signals Sm1 to Sm6 are signals having the magnitudes of signal levels (0V to 5V) of the logic circuits, whereas the drive signals Sr1 to Sr6 are signals having the magnitudes of, for example, +15v to-15v, which are required for controlling the switching elements 311 to 316. The PWM signals Sm1 to Sm6 have the ground potential of the control device 100 as a reference potential, whereas the drive signals Sr1 to Sr6 have the potentials of the terminals (emitter terminals) on the negative sides of the corresponding switching elements as reference potentials.
Fig. 9 is a functional block diagram showing an example of the control device 100 of fig. 4. As shown in fig. 9, the control device 100 includes an operation control unit 102 and an inverter control unit 110.
The operation control unit 102 outputs an instruction signal based on the instruction signal Qe supplied from the power detection unit 90. The electric quantity detection unit 90 receives an electric quantity command signal based on an electric signal indicating a room temperature (temperature of the air-conditioning target space) detected by a temperature sensor (not shown) and a command signal indicating instruction information from an operation unit (not shown) such as a remote controller, and controls the operation of each part of the air conditioner. The instruction from the operation unit includes information indicating the set temperature, selection of the operation mode, and instructions for starting and ending the operation.
The operation control unit 102 determines, for example, whether the stator winding of the motor 7 is connected in a Y-type or delta-type, and determines the target rotation speed, and outputs the switching control signal Sc and the frequency command value ω based on the determination * . For example, when the difference between the room temperature and the set temperature is large, it is determined that the delta-type connection is established, the target rotation speed is set to a relatively high value, and after the start, a frequency command value ω for gradually increasing the frequency to a frequency corresponding to the target rotation speed is output * 。
After reaching the frequency corresponding to the target rotation speed, the state is maintained until the room temperature approaches the set temperature, after the room temperature becomes closer to the set temperature, the motor is stopped once, the motor is switched to Y-type connection, and the frequency command value omega gradually rising to the frequency corresponding to the relatively low target rotation speed is output * . After the frequency corresponding to the target rotation speed is reached, control for maintaining the state where the room temperature is close to the set temperature is performed. The control includes adjustment of the frequency, stopping and restarting of the motor, and the like.
As shown in fig. 9, the inverter control unit 110 includes a current restoration unit 111, a three-phase/two-phase conversion unit 112, a frequency compensation unit 113, a primary frequency calculation unit 114, a voltage command calculation unit 115, a two-phase/three-phase conversion unit 116, a PWM generation unit 117, an electrical angle phase calculation unit 118, and an excitation current command control unit 119.
The current restoring unit 111 restores the phase current i flowing through the motor 7 based on the value of the dc current Idc detected by the bus current detecting means 85 (fig. 4) u 、i v 、i w And (5) recovering. The current restoring unit 111 samples the dc current Idc detected by the bus current detecting means 85 at a timing determined based on the PWM signal supplied from the PWM generating unit 117, thereby generating a phase current i u 、i v 、i w And (5) recovering.
The three-phase/two-phase conversion unit 112 uses the electrical angle phase θ generated by the electrical angle phase calculation unit 118 described later to restore the current value i restored by the current restoration unit 111 u 、i v 、i w Converted into exciting current component (also called gamma-axis current) i γ Torque current component (also referred to as "delta-axis current") i δ The current value of the gamma-delta axis is shown.
The excitation current command control unit 119 controls the torque current component (delta-axis current) i δ The most suitable excitation current command value i that is optimal in efficiency for driving the motor 7 is obtained γ * . In fig. 9, the torque current component i is shown as δ Obtaining exciting current command value i γ * But according to the exciting current component i γ And a frequency command value omega * Obtaining exciting current command value i γ * The same effect can be obtained.
The excitation current command control unit 119 is based on the torque current component i δ (or excitation current component i) γ Frequency command value ω * ) Output exciting current command value i γ * The exciting current command value i γ * For example, the current phase angle βm (not shown) is such that the output torque is equal to or higher than a predetermined value (or maximum), that is, the current value is equal to or lower than a predetermined value (or minimum).
Fig. 10 is a diagram showing the voltage command calculation unit 115 of fig. 9 in detail. As shown in fig. 10, the voltage command operation unit 115 is based on the γ -axis current i obtained by the three-phase two-phase conversion unit 112 γ Delta-axis current i δ Frequency command value ω * And an excitation current command value i obtained by the excitation current command control section 119 γ * To perform an operation to output a voltage command value V γ * 、V δ * 。
The controller 1152 is, for example, a proportional-integral (PI) controller, and is based on a frequency command value ω * A difference (ω) from the frequency estimation value ωest generated by the frequency estimation unit 1151 * - ωest), outputting the frequency estimate ωest and the frequency command value ω * Delta-axis current command value i as uniform δ * 。
Frequency estimation unit 1151 is based on gamma-axis current i γ Delta-axis current i δ And a voltage command value V γ * 、V δ * The frequency of the motor 7 is estimated to generate a frequency estimation value ωest.
The switching unit 1155 outputs the delta-axis current command value i δ * And 0 selects a delta-axis current command value i δ ** A controller 1156, such as a PI controller, outputs a delta-axis current i δ And delta-axis current command value i δ ** Delta-axis voltage command value V as uniform δ * 。
Switching unit 1153 outputs gamma-axis current command value i γ * And 0 selects a gamma-axis current command value i δ ** A controller 1154, such as a PI controller, outputs a gamma current i γ With gamma-axis current command value i γ ** Gamma-axis voltage command value V as uniform γ * 。
The two-phase/three-phase conversion unit 116 shown in fig. 9 uses the electrical angular phase θ obtained by the electrical angular phase calculation unit 118 to obtain the γ -axis voltage command value V obtained by the voltage command calculation unit 115 γ * Delta-axis voltage command value V δ * (voltage command value of two-phase coordinate system) to output voltage command value (three-phase voltage command value) V of three-phase coordinate system u * 、V v * 、V w * And output.
PWM generation unit 117 rootBased on the three-phase voltage command value V obtained by the two-phase/three-phase conversion unit 116 u * 、V v * 、V w * PWM signals Sm1 to Sm6 are generated and outputted.
The stop signal St supplied from the operation control unit 102 is supplied to the PWM generation unit 117, for example, and when the PWM generation unit 117 receives the stop signal St, the output of the PWM signals Sm1 to Sm6 is stopped immediately.
The driving circuit 350 shown in fig. 5 generates driving signals Sr1 to Sr6 from the PWM signals Sm1 to Sm 6.
In the example of fig. 9, the recovery phase current i from the dc current Idc at the input side of the inverter 30 is described u 、i v 、i w However, a current detector may be provided in the output lines 331, 332, 333 of the inverter 30, and the phase current may be detected by the current detector. In this case, the current detected by the current detector may be used instead of the current restored by the current restoration unit 111.
When a three-phase permanent magnet synchronous motor is used for the motor 7, if an excessive current flows in the motor 7, irreversible demagnetization of the permanent magnet occurs, and the magnetic force decreases. When such a state occurs, the current for outputting the same torque increases, and thus there is a problem that the loss increases. Thus, in the phase current i u 、i v 、i w Or, when the direct current Idc is input to the control device 100 and an excessive current flows in the motor 7, the PWM signals Sm1 to Sm6 are stopped to stop the energization of the motor 7, whereby irreversible demagnetization can be prevented. In addition, by setting the slave phase current i u 、i v ，i w Or LPF (Low Pass Filter) for removing noise from DC Idc, the PWM signals Sm 1-Sm 6 can be prevented from being stopped by noise, thereby further improving reliability.
Here, when a structure switchable between either of the Y-coupling and the Δ -coupling is used as the motor 7, an irreversible demagnetization current occurs between the Y-coupling and the Δ -couplingValue (I of FIG. 8) Y And I Δ ) Presumably hasThe delta-type bond is higher than the Y-type bond by a multiple of the difference>Multiple times. Therefore, when the protection level of irreversible demagnetization is set in match with the Y-type coupling, I Δ The protection of (c) is applied earlier, so that it is difficult to expand the operation range. Accordingly, the protection level is switched in the control device 100 in accordance with the Y-type connection and the delta-type connection, so that the motor 7 can be reliably protected from irreversible demagnetization in each winding, and a motor drive device with improved reliability can be obtained.
The protection level may be set to a current value (for example, a current value at which the magnetic force is reduced to 97%) within a range that the magnetic force in the initial state of the motor 7 is set to 100% and the protection level is set to a value that does not affect the performance when irreversible demagnetization occurs, but there is no problem in changing the set current value of the protection level depending on the equipment used.
1-3 operations according to embodiment 1
The operation of the motor drive device 2 when the switching of the switches 61 to 63 connected to the switching device 60 is performed during the operation of the motor 7 (that is, during the rotation operation) will be described below. First, the operation of the motor drive device according to the prior art, which does not have the features of the present invention, will be briefly described with reference to fig. 4.
Operation of the motor drive device of comparative example
During motor operation, that is, when current flows in the switches 61, 62, 63 constituting the connection switching device 60, and current flowing in the exciting coils 611, 621, 631 is operated, the common contacts 61c, 62c, 63c are switched to be connected to the normally closed contacts 61b, 62b, 63b or the normally open contacts 61a, 62a, 63 a. When switching occurs, power supply from inverter 30 to motor 7 is continued, and when rotation speed Nm of motor 7 has not become zero, arc discharge occurs between the contacts of switches 61, 62, 63, and thus a failure such as contact welding may occur.
In order to avoid such a failure, the power supply from inverter 30 to motor 7 is stopped before connection switching device 60 is operated, and the rotation speed Nm of motor 7 is set to zero (that is, the rotation operation is stopped), so that switching can be performed without arcing between the contacts of switches 61, 62, 63.
However, when the rotation speed Nm of the motor 7 is set to zero, the load applied to the motor 7 when restarting the motor 7, for example, in the case of the compressor 904 (fig. 1), is unstable, and therefore the torque required for restarting increases, the current at the time of starting increases, and in the worst case, the restarting may not be possible. Therefore, it is necessary to restart the refrigerant after a lapse of time before the state of the refrigerant is sufficiently stabilized without operating the motor 7. Therefore, the compressor 904 is no longer capable of pressurizing the refrigerant, and the temperature may not be kept constant because of the increase or decrease in the room temperature caused by the decrease in the cooling and heating capacities.
Operation of the motor drive device 2
In the motor 7 according to embodiment 1, the value (effective value) of the current flowing through the winding of the motor 7 or the connection switching device 60 during the rotation operation of the motor 7 (during the operation) is controlled to be close to zero, and the switching of the connection switching device 60 is completed without arc discharge occurring between the contacts of the switches 61, 62, 63 by operating the switches in this state (during the current control period Pc).
The current control period Pc is a period in which an ac voltage is applied to the motor to cancel back electromotive force generated by the rotation operation of the motor 7. In this way, the connection state of the windings 71 to 73 can be switched without setting the rotation speed Nm of the motor 7 to zero, that is, without stopping the rotation operation. Therefore, in the case of the air conditioner, the rotation operation of the motor 7 does not need to be stopped at the time of switching the connection state, and therefore, the waiting time before the refrigerant is stabilized by stopping the rotation operation is not required, and the rise or fall of the room temperature can be suppressed.
In fig. 10, the voltage command operation unit 115 uses the switching unit 1155 to command the delta-axis current command value i δ ** The mode of 0 is selected to operate, so that delta-axis current i is output δ And delta-axis current command value i δ * As a coincidence, i.e. delta-axis current command value i δ ** Delta-axis voltage command value V equal to 0 δ * . The voltage command operation unit 115 uses the switching unit 1153 to command the value i to the γ -axis current γ ** The mode of 0 is selected to operate, thereby outputting gamma-axis current i γ With gamma-axis current command value i γ * As a coincidence, i.e. gamma-axis current command value i γ ** Gamma-axis voltage command value V equal to 0 γ * 。
1-4 effects of embodiment 1
With the above operation, control (preferably control to zero) is performed such that the value (effective value) of the current flowing through the windings of the motor 7, that is, the current flowing through the switches 61 to 63, is close to zero as in the current control period Pc shown in fig. 11 (hereinafter referred to as "zero current control"). This makes it possible to perform switching operation of the switches 61 to 63 in a state where no current flows in the switches 61 to 63, and arc discharge does not occur between the contacts of the switches 61 to 63. Therefore, when the mechanical relay is used as the switches 61 to 63, the contact welding can be prevented, and the highly reliable motor driving device can be realized. The term "control to zero" as used herein means not to accurately set the value (effective value) of the current flowing through the switches 61 to 63 to zero but to be close to zero to the extent that the current can be regarded as substantially zero.
In addition, when the switching operation of the switches 61 to 63 is performed during the current control period, the switching can be performed without causing a large current change in the drive current supplied to the winding. Therefore, abrupt changes in the rotational speed of the motor 7 due to switching can be suppressed, and noise (japanese: sound) and vibration of the motor 7 can be suppressed to switch the wiring state.
As a method of setting the drive current supplied to the windings to 0, there is also a method of stopping the output of the PWM signals Sm1 to Sm6, but the motor 7 continues to generate the counter electromotive force corresponding to the rotation speed Nm. When the counter electromotive force is higher than the bus voltage V20 (i.e., the voltage between the two electrodes of the capacitor 20), the counter electromotive force acts as a regenerative voltage, and a charging current from the motor 7 to the capacitor 20 flows through the connection switching device 60 and the rectifying elements 321 to 326. When the connection switching device 60 is operated in this state to perform the switching operation of the switches 61 to 63, arc discharge may occur, and in this case, a failure such as welding of the contact may occur.
Then, when the motor 7 rotates at a high speed, the control device 100 according to embodiment 1 controls the value (for example, the effective value) of the current flowing through the motor 7 or the connection switching device 60 to be close to zero (preferably, to be approximately 0), and controls the switching operation of the switches 61 to 63 of the connection switching device 60 in this state. By providing this, occurrence of noise and vibration due to current change at the time of switching operation of the switches 61 to 63 can be suppressed. In addition, a failure such as contact welding in the case where the mechanical relay is used for the connection switching device 60 can be prevented, and a highly reliable motor driving device can be obtained.
In other words, even when the connection switching device 60 is configured by inexpensive components, the motor driving device 2 according to embodiment 1 can achieve a reduction in the failure occurrence rate and a longer life of the device, and therefore can reduce the product cost.
Further, since the current values at which irreversible demagnetization occurs in the Y-type coupling and the Δ -type coupling are different, protection corresponding to each winding can be performed by switching the protection level at the timing of switching the Y-type coupling and the Δ -type coupling. However, in the case of using a mechanical relay, a time delay occurs from when a current is applied to the exciting coils 611, 621, 631 until the switches 61, 62, 63 are switched to the normally open contacts 61a, 62a, 63a or the normally closed contacts 61b, 62b, 63 b. Therefore, for example, in the case where the Y-type coupling has been switched to the Δ -type coupling, the protection level is switched to the Δ -type coupling, but the motor 7 is in the transition of the switching to the Δ -type coupling, so it is estimated that the state of the Y-type coupling is still maintained. In this case, when an excessive current is erroneously applied, irreversible demagnetization of the motor 7 may occur.
Then, the protection level of the Y-type coupling, which is set to be a low protection level, is set in advance at the time of starting the control to set the current to zero at the time of switching the wiring, or in the period from the time of starting the control to set the current to zero to the time of switching the wiring, whereby irreversible demagnetization can be prevented from occurring in either the Y-type coupling or the delta-type coupling at the time of switching the wiring. Since the control to zero the current is performed at the time of switching the wiring, it is needless to say that the operation of the motor 7 is not affected.
As described above, the protection level may be set to a current value (for example, a current value at which the magnetic force is reduced to 97%) within a range that the magnetic force in the initial state of the motor 7 is set to 100% and the performance is not affected when irreversible demagnetization occurs, and the current value in the delta connection is set in advance to the Y connectionThe value of the factor of two, so that no irreversible demagnetization occurs, regardless of the wiring state, can be reliably protected. Wherein I is not detected in FIG. 8 (b) Δ But in the case of protection by detecting the value of the current flowing in the winding, it is preferable to add +.>The current value of (a) is set to the protection level (equal to the current value of the protection level in the Y-type connection). In addition, there is no problem even if the set current value of the protection level is changed according to the apparatus used.
1-5 modification of embodiment 1
As the rectifying elements 11 to 14 of the rectifying circuit 10, diodes or the like are generally used. However, the structure of the rectifier circuit 10 is not limited to the example of fig. 2. For example, the structure may be as follows: instead of the rectifying elements 11 to 14 of the rectifying circuit 10, a Transistor element (semiconductor switch) such as a MOSFET (Metal-Oxide-Semiconductor Field-Effect-Transistor) is used, and the rectifying is performed by turning on the rectifying element in accordance with the polarity of the voltage (input ac voltage) supplied from the ac power supply 4.
As the switching elements 311 to 316 of the inverter main circuit 310, IGBTs (Insulated Gate Bipolar Transistor, insulated gate bipolar transistors) or MOSFETs are used, but the present invention is not limited thereto. The switching elements 311 to 316 may be any elements as long as they can be switched. In addition, when MOSFETs are used as the switching elements 311 to 316, since MOSFETs have parasitic diodes in structure, it is not necessary to connect the rectifying elements 321 to 326 (fig. 5) for current return in parallel.
The materials constituting the rectifying elements 11 to 14 and the switching elements 311 to 316 are not only made of silicon (Si), but also made of silicon carbide (SiC), gallium nitride (GaN), diamond, or the like, which are wide band gap semiconductors, so that loss can be further reduced.
Embodiment 2.
The motor drive device according to embodiment 2 of the present invention is different from the motor drive device according to embodiment 1 in that a connection switching device 260 is used instead of the connection switching device 60. In the configuration of fig. 4, a selector switch (selector switch) is used for the switches 61 to 63 connected to the switching device 60. In embodiment 2, each of the switches of the connection switching device 260 is constituted by a combination of a normally closed switch and a normally open switch, that is, a combination of on/off switches.
Fig. 12 is a wiring diagram showing windings 71 to 73 of motor 7 and connection switching device 260 in embodiment 2. In the connection switching device 260 of fig. 12, the switch 61 is configured by a combination of the normally closed switch 615 and the normally open switch 616, the switch 62 is configured by a combination of the normally closed switch 625 and the normally open switch 626, and the switch 63 is configured by a combination of the normally closed switch 635 and the normally open switch 636.
As shown in fig. 12, the windings 71 to 73 of the motor 7 are in a Y-junction state in a state where the normally closed switches 615, 625, 635 are closed (on) and the normally open switches 616, 626, 636 are open (off). In contrast to the illustrated state, the motor is in a delta-type coupled state with normally closed switches 615, 625, 635 open (off) and normally open switches 616, 626, 636 closed (on).
As shown in fig. 12, when each of the switches is constituted by a combination of normally closed switches 615, 625, 635 and normally open switches 616, 626, 636, an electromagnetic contactor can be used as each of the switches. The electromagnetic contactor is preferably small in conduction loss at the time of turning on.
As shown in fig. 12, each of the switches may be configured using a semiconductor switch. Fig. 13 is a circuit diagram showing a configuration example in which MOS transistors are used for the switches 61 (62, 63) of the connection switching device 260 of fig. 12. One of the switches 61, 62, 63 is shown in fig. 13. The switches 61, 62, 63 have the same configuration as each other, and operate similarly. Fig. 14 is a diagram showing an example of on and off states of the MOS transistor of the switch of fig. 13 in a table format.
As shown in fig. 13, the switch 61 (62, 63) includes a MOS transistor 616a (626 a, 636 a) and a diode 616c (626 c, 636 c) connected in series between the lead 61e (62 e, 63 e) and the output line 332 (333, 331), and a MOS transistor 616b (626 b, 636 b) and a diode 616d (626 d, 636 d) connected in series between the lead 61e (62 e, 63 e) and the output line 332 (333, 331).
Further, the switches 61 (62, 63) include MOS transistors 615a (625 a, 635 a) and diodes 615c (625 c, 635 c) connected in series between the leads 61e (62 e, 63 e) and the neutral point node 64, and MOS transistors 615b (625 b, 635 b) and diodes 615d (625 d, 635 d) connected in series between the leads 61e (62 e, 63 e) and the neutral point node 64.
Each MOS transistor 616a (626 a, 636 a), 616b (626 b, 636 b), 615a (625 a, 635 a), 615b (625 b, 635 b) has a parasitic diode with its anode connected to the diode and its cathode connected to the lead (or neutral node or output line).
As shown in fig. 14, the windings 71 to 73 can be connected in delta by turning on the MOS transistors 616a, 626a, 636a, turning on the MOS transistors 616b, 626b, 636b, turning off the MOS transistors 615a, 625a, 635a, and turning off the MOS transistors 615b, 625b, 635 b.
As shown in fig. 14, the windings 71 to 73 can be connected in a Y-type configuration by turning off the MOS transistors 616a, 626a, 636a, turning off the MOS transistors 616b, 626b, 636b, turning on the MOS transistors 615a, 625a, 635a, and turning on the MOS transistors 615b, 625b, 635 b.
In addition, the MOS transistor as the semiconductor switch is preferably constituted by a Wide Band Gap (WBG) semiconductor. The WBG semiconductor includes silicon carbide (SiC), gallium nitride (GaN), and calcium oxide (Ga 2 O 3 ) And diamond as a constituent material. When the WBG semiconductor is used, the on-resistance is small, the loss is low, the element heat generation is small, and the switching operation can be performed quickly.
Even when semiconductor switches are used in this way, the switching operation can be performed at a high speed, but the operation unevenness of about several μs occurs in each semiconductor switch. Therefore, when the time constant L/R based on the winding resistance R and the winding inductance L of the motor 7 is extremely small, there is a possibility that not only a rapid current change occurs and a rapid rotational speed change of the motor 7 occurs to generate vibration and noise, but also semiconductor heat generation may occur to cause a failure.
Therefore, in the connection switching device 260 made of a semiconductor, switching operations of the normally closed switches 615, 625, 635 and the normally open switches 616, 626, 636 are performed in the current control period Pc shown in fig. 11, whereby switching operations of the wiring state can be performed without causing large current changes. Therefore, abrupt changes in the rotational speed of the motor 7 caused by the switching operation in the switcher can be suppressed. Therefore, the wiring state can be switched while suppressing noise and vibration.
In addition, a failure such as contact welding in the case where the mechanical relay is used for the connection switching device 260 can be prevented, and a highly reliable motor driving device can be obtained.
In addition, when the connection switching device 260 uses a semiconductor switch, a failure due to heat generated by the semiconductor switch can be prevented, and a highly reliable motor driving device can be obtained.
In other words, in the motor drive device according to embodiment 2, even when the connection switching device 260 is configured by inexpensive components, the failure occurrence rate can be reduced and the lifetime of the device can be prolonged, so that the product cost can be reduced.
Except for the above points, the motor drive device of embodiment 2 is the same as the motor drive device 2 of embodiment 1.
Embodiment 3.
In embodiments 1 and 2, an example in which the motor driving device to which the present invention is applied is connected to the motor 7 in which the windings 71 to 73 can be switched between the Y-type coupling and the delta-type coupling is described. In embodiment 3, an example in which a motor driving device to which the present invention is applied is connected to a motor 7a capable of switching the number of turns of each of windings 71 to 73 is described. In embodiment 3, for example, a structure in which two or more winding portions are used for the windings 71 to 73 of each phase. In this case, both ends of each of two or more winding portions constituting the windings 71 to 73 of each phase are connected to the outside of the motor 7a, and the connection state (the number of turns of the windings in embodiment 3) of the stator windings 71, 72, 73 is switched by the connection switching device 360. The connection switching device according to the present invention can be applied to a motor in which a winding portion can be switched to any of a parallel connection and a series connection.
Fig. 15 shows a structure in which windings of each phase are formed by two winding portions in a Y-type coupled motor, both ends of each winding portion can be connected to the outside of the motor 7a, and the connection state is switched by a connection switching device 360.
Specifically, the U-phase winding 71 is composed of two winding portions 711 and 712, the V-phase winding 72 is composed of two winding portions 721 and 722, and the W-phase winding 73 is composed of two winding portions 731 and 732.
The 1 st end portions of the winding portions 711, 721, 731 are connected to the output lines 331, 332, 333 of the inverter 30 via the external terminals 71c, 72c, 73c, respectively. The 2 nd ends of the winding portions 711, 721, 731 are connected to common contacts of the switching switches 617, 627 via external terminals 71g, 72g, 73g, respectively.
The 1 st end portions of the winding portions 712, 722, 732 are connected to the common contacts of the switches 618, 628, 638 via the external terminals 71h, 72h, 73h, respectively. The 2 nd end portions of the winding portions 712, 722, 732 are connected to the neutral point node 64 via external terminals 71d, 72d, 73d, respectively.
The normally-closed contacts of the switches 617, 627, 637 are connected to the normally-closed contacts of the switches 618, 628, 638, respectively. The normally open contact of the change-over switch 617, 627, 637 is connected to the neutral node 64.
The normally open contacts of the switches 618, 628, 638 are connected to the output lines 331, 332, 333 of the inverter 30.
The connection switching means 360 is constituted by switching switches 617, 627, 637, 618, 628, 638.
Even when such a connection switching device 360 is used, the switching operation of the switch of the connection switching device 360 is performed in the current control period Pc in the same manner as in the cases of embodiments 1 and 2, and the mechanical relay or the semiconductor switch can be protected.
In the case of the configuration shown in fig. 15, the motor 7a is in the series connection state in a state in which the changeover switches 617, 627, 637, 618, 628, 638 are switched to the normally closed contact side as shown in the figure, and the motor 7a is in the parallel connection state in a state in which the changeover switches 617, 627, 637, 618, 628, 638 are switched to the normally open contact side opposite to the figure.
In embodiment 3, a combination of a normally closed switch and a normally open switch may be used instead of the change-over switch as described in embodiment 2. In addition, a normally closed switch and a normally open switch can be used as the semiconductor switch.
Although the case where the series connection state and the parallel connection state are switched in the Y-type coupled motor 7a has been described above, the present invention can be applied to the motor drive device of the delta-type coupled motor in the case where the series connection state and the parallel connection state are switched in the same manner as described above.
The present invention can also be applied to a motor drive device having a motor with the following structure: in the Y-type connection or delta-type connection state, a center tap is provided in the winding, and a part of the winding is short-circuited by a switching member, thereby changing the voltage required for driving. In short, the present invention can be applied to any structure in which the motor can switch the connection state of the windings and the counter electromotive force is switched by the switching of the connection state.
Except for the above points, the motor driving device of embodiment 3 is the same as that of embodiment 1 or 2.
The configurations described in embodiments 1 to 3 are examples of the configuration of the present invention, and may be combined with other known techniques.
Description of the reference numerals
2. A motor driving device; 4. an alternating current power supply; 7. 7a, a motor; 8. a reactor; 10. a rectifying circuit; 20. a capacitor; 30. a transducer; 60. 260, 360, connection switching means; 61-63, a switcher; 71-73, winding; 80. a control power supply generating circuit; 85. a bus current detecting section; 100. a control device; 102. an operation control unit; 110. a converter control unit; 900. 900a, 900b, a refrigeration cycle apparatus; 902. a four-way valve; 904. a compressor; 906. a heat exchanger; 908. an expansion valve; 910. a heat exchanger.
Claims (10)
1. A motor driving apparatus that drives a permanent magnet synchronous motor, wherein,
the motor driving device is provided with a connection switching device, an inverter, a current detecting component and a control device,
the connection switching device has a switch which performs a switching operation of the switch during a rotation operation of the motor to switch a connection state of windings of the motor between Y-type coupling and delta-type coupling,
the inverter applies an alternating voltage to the windings by means of the switch, and a back electromotive force is applied to the windings of the motor during a self-rotation action by means of the switch,
the current detection means detects a current supplied to the inverter,
the control means controls the inverter based on the current detected by the current detecting means to control the rotation of the motor, controls the inverter so that a current of a protection level or less flows in the motor, causes the connection switching means to perform switching of the connection state, the protection level being a set current value switched in accordance with the connection state,
The switching operation of the switcher is performed during a current control period in which the 1 st effective value of the alternating current flowing through the winding is close to zero than the 2 nd effective value of the alternating current flowing through the winding before the switching operation of the switcher, and an alternating voltage is applied to the motor so that the rotational speed of the motor is not zero and counter electromotive force generated by the rotational operation of the motor is canceled,
a 1 st protection level is the protection level when the connection state is the Y-type connection, a 2 nd protection level is the protection level when the connection state is the delta-type connection, the 1 st protection level is set lower than the 2 nd protection level,
the protection level at the time when control is started with the 2 nd effective value of the alternating current flowing through the winding being close to zero, or the protection level during the period from the start of control with the 2 nd effective value of the alternating current flowing through the winding being close to zero to the completion of switching of the connection state is set to the 1 st protection level.
2. The motor driving device according to claim 1, wherein,
During the current control, the inverter applies an alternating voltage to the windings, and a back electromotive force is applied from the windings of the motor.
3. The motor drive apparatus according to claim 1 or 2, wherein,
the switcher has an electromagnetic contactor and,
the electromagnetic contactor has an exciting coil and a contact driven by a current flowing through the exciting coil,
and controlling the current supplied to the exciting coil.
4. The motor drive apparatus according to claim 1 or 2, wherein,
the switcher has a semiconductor switch controlled in accordance with a signal input to a control terminal,
and controlling a signal input to the control terminal.
5. The motor driving device according to claim 4, wherein,
the semiconductor switch is formed of a wide bandgap semiconductor.
6. The motor drive apparatus according to claim 1 or 2, wherein,
the motor is provided with a compressor and,
the current control period is 1 second or less.
7. A refrigerating cycle apparatus, wherein,
the refrigeration cycle apparatus includes the motor drive apparatus according to any one of claims 1 to 5.
8. An air conditioner, wherein,
The air conditioner includes the refrigeration cycle apparatus according to claim 7.
9. A water heater, wherein,
the water heater includes the refrigeration cycle apparatus according to claim 7.
10. A refrigerator, wherein,
the refrigerator includes the refrigeration cycle apparatus according to claim 7.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/JP2017/039117 WO2019087243A1 (en) | 2017-10-30 | 2017-10-30 | Electric motor drive device, refrigeration cycle device, air conditioner, water heater, and refrigerator |
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| CN111264026A CN111264026A (en) | 2020-06-09 |
| CN111264026B true CN111264026B (en) | 2023-09-15 |
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| JP (1) | JP6921221B2 (en) |
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| WO2021084617A1 (en) * | 2019-10-29 | 2021-05-06 | 三菱電機株式会社 | Electric motor drive device, refrigeration cycle device, air conditioner, water heater, and refrigerator |
| WO2021111598A1 (en) * | 2019-12-05 | 2021-06-10 | 東芝キヤリア株式会社 | Motor driving device and refrigeration cycle device |
| WO2021214980A1 (en) * | 2020-04-24 | 2021-10-28 | 三菱電機株式会社 | Electric motor drive device, refrigeration cycle device, air conditioner, water heater, and refrigerator |
| KR102478881B1 (en) | 2020-12-28 | 2022-12-16 | 엘지전자 주식회사 | Motor driving apparatus and air conditioner including the same |
| CN116830451A (en) | 2021-02-17 | 2023-09-29 | 三菱电机株式会社 | Motor driving device, refrigeration cycle device, air conditioner, water heater, and refrigerator |
| AU2021429850B2 (en) * | 2021-02-25 | 2025-01-23 | Mitsubishi Electric Corporation | Electric motor drive device and refrigeration cycle application device |
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Also Published As
| Publication number | Publication date |
|---|---|
| JPWO2019087243A1 (en) | 2020-11-12 |
| JP6921221B2 (en) | 2021-08-18 |
| WO2019087243A1 (en) | 2019-05-09 |
| CN111264026A (en) | 2020-06-09 |
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