JP7034368B1 - Motor drive control device, drive control method and refrigeration air conditioner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a drive control device, a drive control method and a refrigeration air conditioner for controlling a motor used in a refrigeration cycle. A drive control device for controlling a motor used in a refrigeration cycle is provided. The drive control device 100 sends an inverter circuit 122 connected to the motor 102 and a positioning current for fixing or adjusting the position of the rotor of the motor 102 to the motor 102 when the motor 102 is started. The control unit 128 includes a control unit 128 that controls the size of the positioning current according to the state of the refrigeration cycle. [Selection diagram] Fig. 2

Description

The present invention relates to a motor drive control device, a motor drive control method, and a refrigerating air conditioner including a compressor provided with the motor.

When controlling a permanent magnet synchronous motor with an inverter, it is desirable to detect the phase of the motor rotor, but since the inside of a device such as a compressor usually has a high temperature and high pressure, the phase of a hall element or the like inside the device. Difficult to install a detector. Conventionally, for inverter circuits for devices such as compressors, a technique called sensorless control, in which the phase is estimated from the current (motor current) flowing in the motor winding, has been used.

On the other hand, sensorless control is a control method that uses the induced voltage generated when the motor rotates, so the phase estimation accuracy of the motor rotor deteriorates in the low rotation region when a device such as a compressor is started. Will end up. Therefore, a control method called positioning control is known in which a direct current called a positioning current is passed through a motor winding to generate a fixed magnetic field to fix the phase of the rotor. After the positioning control, the phase of the motor current is gradually advanced, that is, the direct current is changed to the alternating current to rotate the motor.

When starting the motor, it is necessary to set the motor current to be sufficiently larger than the expected load torque so that the start does not fail. Therefore, in the past, this motor current was determined from the hardware specifications of the inverter circuit and was set to a fixed value.

US Pat. Disclose the configuration that determines the starting current value. The prior art of Patent Document 1 determines the starting current value which is the amplitude in the synchronous operation mode. On the other hand, with respect to the initial excitation mode before the synchronous operation mode, the current value flowing in each phase is set during normal operation. In the range below the maximum current value (current peak value) that can be passed through each phase, the value is gradually increased from zero. Where a DC component current such as a positioning current exerts thermal stress on an inverter circuit, Patent Document 1 does not disclose an improvement in such a positioning current, and there is still room for improvement in positioning control. rice field.

Japanese Unexamined Patent Publication No. 2008-15782

The present disclosure has been made in view of the above points in the prior art, and the present disclosure stabilizes the start-up of the motor used in the refrigeration cycle and reduces the thermal stress on the inverter circuit during the start-up. To provide a motor drive control device, a drive control method, and a refrigerating air conditioner capable of suppressing fatigue and deterioration of elements of an inverter circuit, and eventually preventing failure and prolonging the life of a device including an inverter circuit. With the goal.

The present disclosure provides a drive control device for controlling a motor used in a refrigeration cycle, which has the following features in order to solve the above problems. The drive control device includes an inverter circuit connected to the motor and a control unit. When the motor is started, the control unit controls the inverter circuit so that a positioning current for fixing or adjusting the position of the rotor of the motor flows through the motor. The control unit adjusts the magnitude of the positioning current according to the state of the refrigeration cycle.

Further, according to the present disclosure, a refrigerating air conditioner having the following features may be provided. The refrigerating air conditioner includes a heat exchanger, a compressor including a motor, an inverter circuit connected to the motor, and a control unit for controlling the inverter circuit. When the motor is started, the control unit controls the inverter circuit so that a positioning current for fixing or adjusting the position of the rotor of the motor flows through the motor. The control unit determines the magnitude of the positioning current according to the state of the refrigeration cycle.

Further, according to the present disclosure, a drive control method for controlling a motor used in a refrigeration cycle may be provided, which has the following characteristics. The drive control method is a step of determining the magnitude of the positioning current to be passed to fix or adjust the position of the rotor of the motor according to the state of the refrigeration cycle, and the magnitude determined when the motor is started. Includes a step of controlling the inverter circuit connected to the motor so that the positioning current flows through the motor according to.

In addition, the problems disclosed in the present application and the solutions thereof will be clarified by the columns and drawings of the mode for carrying out the invention.

According to the above configuration, the start of the motor used in the refrigeration cycle is stabilized, the thermal stress on the inverter circuit at the time of start is reduced, the fatigue and deterioration of the elements of the inverter circuit are suppressed, and the inverter circuit is formed. It is possible to prevent failures of the including devices and extend their life.

FIG. 1 is a configuration diagram of an air conditioner according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a motor drive control device according to an embodiment of the present invention. FIG. 3 is a flowchart showing a process of determining the magnitude of the current value at the time of starting the compressor executed by the inverter controller in the motor drive control device according to the embodiment of the present invention. FIG. 4 is a diagram schematically showing a time change of a current value during positioning control and synchronous control based on a determination by a motor drive control device according to the present embodiment. FIG. 5 is a graph plotting the time change of the current value and the load torque during the positioning control, the synchronous control, and the sensorless control in the motor drive control device according to the present embodiment. FIG. 6 is a graph plotting changes in the current value over time and changes in the phase of the rotor during positioning control and synchronous control when starting from various initial phases. FIG. 7 is a diagram schematically showing a time change of a current value during positioning control and synchronous control accompanied by phase adjustment according to a preferred embodiment. FIG. 8 is a graph plotting changes in the current value over time and changes in the phase of the rotor during positioning control and synchronous control with phase adjustment according to a preferred embodiment when starting from various initial phases.

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but the embodiments of the present invention are not limited to the specific embodiments described below. In the drawings, the same reference numerals indicate the same or corresponding parts.

In the present disclosure, a drive control device for controlling a motor used in a refrigeration cycle, a drive control method for controlling a motor used in a refrigeration cycle, and a refrigerated air conditioner including a drive control device (hereinafter, air conditioning is abbreviated as air conditioning). There is.) Target the machine. The drive control device according to the embodiment of the present invention determines the position of the inverter circuit connected to the motor used in the compressor, for example, and the position of the rotor of the motor when the motor is started, for example, in the refrigeration cycle of the refrigerating air conditioner. It is provided with a control unit that controls an inverter circuit so that a positioning current for fixing or adjusting flows to a motor, and the control unit is characterized in that the magnitude of the positioning current is adjusted according to the state of the refrigeration cycle. .. As a result, the start-up of the motor used in the refrigeration cycle is stabilized, the thermal stress on the inverter circuit at the time of start-up is reduced, the fatigue and deterioration of the elements of the inverter circuit are suppressed, and the failure of the device is prevented. Aim to extend the service life.

Hereinafter, with reference to the drawings, a freezing device comprising a drive control device for controlling a motor used in a refrigeration cycle, a drive control method for controlling a motor used in the refrigeration cycle, and a drive control device with a more specific embodiment. The air conditioner will be described.

Hereinafter, a motor drive control device and a drive control method thereof according to the embodiment of the present invention will be described with reference to FIGS. 1 to 5. The embodiments shown in FIGS. 1 to 5 correspond to a motor drive control device for an air conditioner as an example of a refrigerating air conditioner and a drive control method thereof. Here, the refrigerating air conditioner (frozen air conditioning equipment) is a general term for equipment using a refrigerant and a refrigerating cycle, such as an air conditioner, a refrigerator, and a freezer. More specifically, examples of refrigerated air conditioners include air conditioners such as room air conditioners and gas engine heat pump air conditioners, heat source equipment such as refrigerators and chilling units, showcases, refrigerators and freezers, unit coolers, and ice makers. Refrigerators for transportation, refrigerating equipment for transportation such as car air conditioners, heat pump water heaters, etc. may be included, but in the following description, an air conditioner will be described as an example.

Hereinafter, the overall configuration of an air conditioner 1 as an example of a refrigerating air conditioner to which a motor drive control device and a drive control method thereof are mounted will be described with reference to FIG. 1.

FIG. 1 is a configuration diagram of an air conditioner 1 according to the present embodiment. The air conditioner 1 shown in FIG. 1 is a device that switches between a cooling operation and a heating operation, and includes a refrigerant circuit Q and a control device 30. In FIG. 1, the direction in which the refrigerant flows in the refrigerant circuit Q during the cooling operation is indicated by a solid arrow. Hereinafter, unless otherwise specified, the cooling operation is assumed, but the direction is reversed during the heating operation. The refrigerant will circulate.

The refrigerant circuit Q is configured by sequentially connecting a compressor 11, an outdoor heat exchanger 13, an indoor expansion valve 21, and an indoor heat exchanger 22. The refrigerant circuit Q includes each device installed in the outdoor unit 10, each device installed in the indoor unit 20, and connection pipes k1 and k3.

The outdoor unit 10 includes a compressor 11, an accumulator 12, an outdoor heat exchanger 13, an outdoor fan 14, a four-way valve 15, a gas blocking valve 18a, a liquid blocking valve 18b, and sensors 19.

The compressor 11 compresses the gaseous refrigerant flowing in through the accumulator 12 according to a command from the control device 30. The compressor 11 includes a motor that is controlled and driven by the inverter circuit in this embodiment. The compressor 11 is not particularly limited, but a scroll compressor can be used.

The accumulator 12 is installed on the suction side of the compressor 11 and separates the refrigerant flowing from the indoor heat exchanger 22 into gas and liquid. By providing the accumulator 12, liquid compression in the compressor 11 is prevented, and the dryness of the refrigerant sucked into the compressor 11 is appropriately adjusted.

The outdoor heat exchanger 13 is a heat exchanger in which heat exchange is performed between the high-temperature and high-pressure refrigerant discharged from the compressor 11 and the outside air sent by the outdoor fan 14. The outdoor heat exchanger 13 functions as a condenser that condenses the refrigerant compressed by the compressor 11 in the cooling operation. In the example shown in FIG. 1, the upstream end of the outdoor heat exchanger 13 is connected to the discharge port of the compressor 11 via the four-way valve 15. The downstream end of the outdoor heat exchanger 13 is connected to the indoor heat exchanger 22 via a liquid blocking valve 18b, a connection pipe k3, and an indoor expansion valve 21 in that order.

The outdoor fan 14 is installed in the vicinity of the outdoor heat exchanger 13, and sends outside air to the outdoor heat exchanger 13 in accordance with a command from the control device 30.

The four-way valve 15 is a valve that switches the direction in which the refrigerant flows in the refrigerant circuit Q. During the cooling operation, the four-way valve 15 is switched to the flow path shown by the solid line, and the compressor 11, the outdoor heat exchanger 13 (acts as a condenser in the cooling operation), the indoor expansion valve 21, and the indoor heat exchange. The refrigerant circulates in the refrigerant circuit Q in which the vessel 22 (which functions as an evaporator in the cooling operation) is sequentially connected in an annular shape. On the other hand, during the heating operation, the four-way valve 15 is switched to the flow path shown by the broken line, and the compressor 11, the indoor heat exchanger 22 (acts as a condenser in the heating operation), and the indoor expansion valve 21. And the outdoor heat exchanger 13 (which functions as an evaporator in the heating operation) are sequentially connected in a ring shape, and the refrigerant circulates in the refrigerant circuit Q.

The gas blocking valve 18a and the liquid blocking valve 18b are valves for spreading the refrigerant sealed in the outdoor unit 10 to the entire refrigerant circuit Q by opening the valves after the installation work of the air conditioner 1. One side of the gas blocking valve 18a (downstream side of the cooling operation) is connected to the four-way valve 15, and the other side (upstream side of the cooling operation) is connected to the indoor heat exchanger 22 via the connection pipe k1. There is. One side (upstream side of cooling operation) of the liquid blocking valve 18b is connected to the outdoor heat exchanger 13, and the other side (downstream side of cooling operation) is connected to the indoor expansion valve 21 via the connection pipe k3. ing.

The sensors 19 of the outdoor unit 10 include a suction pressure sensor 19a, a discharge pressure sensor 19b, a discharge temperature sensor 19c, a temperature sensor 19d, an outside air temperature sensor 19g, and an outdoor heat exchanger intermediate temperature sensor 19h.

The suction pressure sensor 19a is installed on the suction side of the compressor 11 and detects the pressure of the refrigerant sucked into the compressor 11. The discharge pressure sensor 19b is installed on the discharge side of the compressor 11 and detects the pressure of the refrigerant discharged from the compressor 11. The discharge temperature sensor 19c is installed near the discharge port of the compressor 11 and detects the temperature of the refrigerant discharged from the compressor 11. The temperature sensor 19d is installed on the upstream side of the accumulator 12 and detects the temperature thereof. The outside air temperature sensor 19g is installed at a predetermined position of the outdoor unit 10 and detects the temperature of the outside air. The outdoor heat exchanger intermediate temperature sensor 19h is installed in the outdoor heat exchanger 13 and has a temperature near the intermediate portion of the outdoor heat exchanger 13 (the intermediate portion of the heat transfer tube through which the refrigerant flows) (hereinafter referred to as the intermediate temperature). Refer to.) Is detected.

In FIG. 1, the signal line is indicated by a broken line arrow, and the detected values of these sensors 19 are output to the control device 30.

The indoor unit 20 includes an indoor expansion valve 21, an indoor heat exchanger 22, an indoor fan 23, an indoor solenoid valve 24, and an indoor heat exchanger intermediate temperature sensor 25.

The indoor expansion valve 21 is a valve that reduces the pressure of the refrigerant condensed by the outdoor heat exchanger 13. The indoor expansion valve 21 has a function of reducing the pressure of the refrigerant from the outdoor heat exchanger 13 toward the indoor heat exchanger 22 via the connection pipe k3 in the cooling operation. The opening degree of the indoor expansion valve 21 is adjusted by the control device 30.

The indoor heat exchanger 22 is a heat exchanger in which heat exchange is performed between the refrigerant decompressed by the indoor expansion valve 21 and the indoor air (air in the air-conditioned space). In the cooling operation, the indoor heat exchanger 22 functions as an evaporator that evaporates the refrigerant decompressed by the indoor expansion valve 21. Then, the indoor air is cooled by the latent heat of vaporization of the refrigerant flowing through the indoor heat exchanger 22.

The indoor fan 23 is installed near the indoor heat exchanger 22, and sends indoor air to the indoor heat exchanger 22 according to a command from the control device 30. The indoor solenoid valve 24 is installed on the upstream side of the indoor expansion valve 21 and is opened to allow the refrigerant to flow when operating the indoor unit 20. If the indoor expansion valve 21 has a structure that can be fully closed, the indoor solenoid valve 24 can be omitted.

The indoor heat exchanger intermediate temperature sensor 25 is installed in the indoor heat exchanger 22 and detects the temperature in the vicinity of the intermediate portion of the indoor heat exchanger 22.

In FIG. 1, the signal line is indicated by a broken line arrow, but the detection value of the indoor heat exchanger intermediate temperature sensor 25 is output to the control device 30.

Although not shown, the control device 30 includes a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and various interfaces. The program stored in the ROM is read out and expanded in the RAM, and the CPU executes various processes. Further, the control device 30 includes a motor drive control device described later, and includes a compressor 11 and an indoor expansion valve 21 based on the detection values of the sensors 19 and 25 described above and the operation signal from the remote controller. Control each device.

Hereinafter, the motor drive control device 100 and the drive control method thereof according to the embodiment of the present invention will be described with reference to FIG. The embodiment shown in FIG. 2 corresponds to a drive control device and a drive control method for the motor 102 for an air conditioner included in the compressor 11. The motor 102 is an AC motor, more specifically, a synchronous motor, and typically, a permanent magnet synchronous motor (PMSM, Permanent Magnet Synchronous Motor) having a predetermined number of magnetic poles is used.

FIG. 2 is a diagram showing the overall configuration of the motor drive control device 100 according to the present embodiment. The motor drive control device 100 shown in FIG. 2 is not particularly limited, but can be mounted on the control device 30 shown in FIG. As shown in FIG. 2, the AC power supply 101 and the motor 102 are connected to the motor drive control device 100, and the motor drive control device 100 mainly includes a converter unit 110 and an inverter unit 120.

The converter unit 110 includes a rectifier circuit 111, a smoothing reactor 113, and a smoothing capacitor 114.

The AC power supply 101 is a three-phase AC power supply, and correspondingly, the rectifier circuit 111 is configured as a three-phase full-wave rectifier circuit. The rectifier circuit 111 has a three-phase bridge configuration using six diodes (a thyristor may be used instead of the diode) 112. The rectifier circuit 111 is connected to the AC power supply 101, converts the AC voltage from the AC power supply 101 into a DC voltage, and outputs the AC voltage to the inverter unit 120.

The smoothing reactor 113 and the smoothing capacitor 114 are connected to the DC output terminal of the rectifier circuit 111. The smoothing reactor 113 and the smoothing capacitor 114 form a DC filter and smooth the DC voltage output from the rectifier circuit 111.

The inverter unit 120 includes a DC voltage detection unit 121, an inverter circuit 122, current sensors 125 and 126, a gate drive circuit 127, and an inverter controller 128. The DC voltage from the converter unit 110 is input to the inverter unit 120.

The DC voltage detection unit 121 is provided on the input side of the inverter circuit 122, detects the DC voltage of the output of the rectifier circuit 111 (both ends of the smoothing capacitor 114), and outputs the detected voltage value to the inverter controller 128.

The inverter circuit 122 converts the DC power from the converter unit 110 into AC power and outputs it to the motor 102, which is an AC load. The inverter circuit 122 constitutes a three-phase bridge circuit by six semiconductor switching elements 123 and diodes 124 connected in antiparallel to each semiconductor switching element 123, corresponding to three-phase AC. The diode 124 connected in antiparallel to each switching element 123 is a diode for commutation operation when each switching element 123 is off.

The gate drive circuit 127 is a circuit that drives the pulse width modulation of the inverter circuit 122 (hereinafter, the pulse width modulation may be referred to as PWM (Pulse Width Modulation)) under the control of the inverter controller 128.

The inverter circuit 122 turns on a semiconductor switching element 123 such as an IGBT (Insulated Gate Bipolar Transistor) or a power MOS (Metal-Oxide-Semiconductor) FET (Field-Effect Transistor) according to a PWM signal input from the gate drive circuit 127. The OFF operation is performed, the DC voltage which is the output of the converter unit 110 is converted into an AC voltage and output, and the rotation speed of the motor 102 is controlled.

The current sensors 125 and 126 detect the AC voltage of the AC output and output the measured value to the inverter controller 128.

The inverter controller 128 controls the gate drive circuit 127 based on the detection signals of the DC voltage value from the DC voltage detection unit 121 and the AC current value from the current sensors 125 and 126 to generate a PWM signal. As the inverter controller 128, an arithmetic processing unit such as a microcomputer or a DSP (Digital Signal Processor) can be used. The inverter controller 128 also includes a sampling hold circuit and an A / D (Analog / Digital) converter, and each input voltage / current detection signal is converted into a digital signal.

In the circuit configuration shown in FIG. 2, the inverter controller 128 passes through the gate drive circuit 127 to the inverter circuit in response to the condition (power on, etc.) that triggers the activation of the compressor 11 is satisfied. By inputting a predetermined PWM signal to 122, the compressor 11 (and its motor 102) is started, and the compressor 11 is operated at a required rotation speed.

As described above, when the motor built in the compressor (for example, a permanent magnet synchronous motor) is controlled by an inverter, it is desirable to detect the phase (mechanical angle) of the motor rotor. However, since the inside of the compressor has a high temperature and high pressure, it is difficult to install an element for phase detection such as a Hall element inside the compressor. Therefore, in general, sensorless control is performed in which the phase is estimated from the current (motor current) flowing in the motor winding.

On the other hand, sensorless control is a control method that uses the induced voltage generated when the motor rotates, so there is a possibility that the accuracy of rotor phase estimation will decrease in the low rotation region when the compressor is started. be. This is because the induced voltage of the motor increases in proportion to the rotation speed. Therefore, when the compressor 11 is started, it is configured so that the phase information of the motor rotor is not required. Specifically, a DC current called a positioning current is passed through the motor winding to generate a fixed magnetic field. Positioning control for fixing the phase of the rotor and then synchronous control for gradually advancing the phase of the motor current, that is, changing the DC current to an AC current and rotating the motor are performed.

On the other hand, a direct current (direct current component) such as this positioning current exerts a large thermal stress on the inverter circuit, which promotes fatigue and deterioration of the elements constituting the inverter circuit, resulting in failure of the inverter circuit and eventually a device equipped with the inverter circuit. It may cause a decrease in life. Therefore, it is desirable that the initial DC current at the time of starting the motor is as small as possible and short. On the other hand, if the positioning current is made small, the generated torque becomes small, so that if the generated torque is lower than the load torque, step-out is caused and the compressor 11 fails to start.

Therefore, conventionally, from the viewpoint of preventing the step-out of the motor and eventually the start failure of the compressor 11, the design emphasizes the stability at the time of starting, and the motor current is set sufficiently larger than the expected load torque. Therefore, from the hardware specifications of the inverter circuit, a fixed value was used so that sufficient generated torque could be secured. However, since the fixed value is a value with a margin, there is room for further reduction of the positioning current.

Therefore, in the present embodiment, in the motor drive control device 100 including the inverter circuit 122 connected to the motor 102 used in the compressor 11 in the refrigeration cycle of the air conditioner 1 shown in FIG. 1, the inverter controller 128 However, when starting the motor 102, the inverter circuit is controlled so that a positioning current for fixing or adjusting the position of the rotor of the motor flows through the motor, and at that time, the positioning current is adjusted according to the state of the refrigeration cycle. It is configured to adjust the size of the. As a result, the start-up of the motor used in the refrigeration cycle is stabilized, the thermal stress on the inverter circuit at the time of start-up is reduced, the fatigue and deterioration of the elements of the inverter circuit are suppressed, and the failure of the device is prevented. We are trying to extend the service life.

The measured values of various sensors 19a, 19b, 19h, and 25 and the information on the operating state of the air conditioner are input to the inverter controller 128. The state of the refrigerating cycle detected for adjusting the positioning current described above includes the discharge pressure sensor 19b for detecting the discharge pressure of the compressor 11 shown in FIG. 1, the suction pressure sensor 19a for detecting the suction pressure of the compressor 11, and the heat. Detection based on at least one means selected from the group consisting of intermediate temperature sensors 19h, 25 for detecting the intermediate temperature of the exchangers 13 and 22, and means for measuring the elapsed time from stopping the compressor to starting the compressor. Can be done.

More specifically, the state of the refrigeration cycle may be detected based on, for example, the differential pressure between the discharge pressure and the suction pressure of the compressor 11 immediately before the start-up, in which case the positioning current is when the differential pressure is large. It may be adjusted to be large. Further, the state of the refrigeration cycle may be detected based on the intermediate temperature of the heat exchanger. In this case, the positioning current is the heating when the intermediate temperature of the outdoor unit heat exchanger is high in the case of cooling operation. In the case of operation, it may be adjusted to increase when the intermediate temperature is low. Further, in one or a plurality of embodiments, the state of the refrigeration cycle may be detected based on the measured stop elapsed time by measuring the stopped elapsed time from once stopping the compressor 11 to starting the compressor 11. In this case, the positioning current may be adjusted so as to increase in a field where the elapsed time is short.

Hereinafter, how to detect the state of the refrigeration cycle and how to adjust the magnitude of the positioning current based on the detected refrigeration cycle will be described more specifically with reference to FIGS. 3 and 4. ..

FIG. 3 is a flowchart illustrating a process of determining the magnitude of the current value at the time of starting the compressor 11 executed by the inverter controller 128 in the motor drive control device 100 according to the embodiment of the present invention.

The process shown in FIG. 3 starts from step S100, and in step S101, the inverter controller 128 has a pressure difference (differential pressure) between the discharge pressure and the suction pressure of the compressor 11 before (immediately before) starting, and outdoor heat exchange. Find the intermediate temperature of the vessel and the duration of shutdown of the compressor 11. The pressure difference (differential pressure) is obtained by reading the measured values of the discharge pressure sensor 19b and the suction pressure sensor 19a at a time before starting and calculating the difference. The intermediate temperature is obtained by reading the measured value of the intermediate temperature sensor 19h (25 when an indoor heat exchanger is used) at the time before starting. The difference and the intermediate temperature may be the values at one time point before the start-up, or may be the average values at a plurality of time points before the start-up. The stop duration of the compressor 11 can be obtained from the difference between the time stored at the timing when the compressor 11 is stopped, the time acquired at the time before the start, and the stored stop time.

In step S102, the inverter controller 128 compares the obtained pressure difference between the discharge pressure and the suction pressure with a threshold value (hereinafter, the threshold value for the differential pressure is referred to as a threshold value 1), and the obtained pressure difference is the threshold value 1. Judge whether or not it exceeds. If it is determined in step S102 that the obtained pressure difference exceeds the threshold value 1 (YES), the process is branched to step S103. In step S103, the stage is raised by one and the process proceeds to step S104. This is because when the differential pressure is large, the load torque applied to the compressor 11 is large, and it is necessary to increase the motor current. On the other hand, if it is determined in step S102 that the obtained pressure difference does not exceed the threshold value 1 (NO), the process directly proceeds to step 104.

In step S104, the inverter controller 128 compares the obtained intermediate temperature with the threshold value (hereinafter, the threshold value for the intermediate temperature is referred to as the threshold value 2), and determines whether or not the obtained intermediate temperature exceeds the threshold value 2. judge. If it is determined in step S104 that the obtained intermediate temperature exceeds the threshold value 2 (YES), the process is branched to step S105. In step S105, the stage is raised by one and the process proceeds to step S106. For example, in the cooling operation, when the intermediate temperature of the outdoor heat exchanger 13 is higher than the outside air temperature, it is estimated that the discharge pressure is high, so it is necessary to increase the motor current. On the other hand, if it is determined in step S104 that the obtained intermediate temperature does not exceed the threshold value 2 (NO), the process directly proceeds to step 106. In the case of heating operation, the load torque increases when the intermediate temperature of the outdoor heat exchanger 13 is lower than the outside air temperature, so it is necessary to increase the motor current when the intermediate temperature is lower than another threshold value. If there is, you can raise the stage by one. Also, when using the intermediate temperature of the indoor heat exchanger, these are reversed.

In step S106, the inverter controller 128 compares the obtained stop duration with the threshold value (hereinafter, the threshold value for the stop duration is referred to as the threshold value 3), and whether the obtained stop duration is below the threshold value 3. Judge whether or not. If it is determined in step S106 that the obtained stop duration is below the threshold value 3 (YES), the process is branched to step S107. In step S107, the stage is raised by one and the process proceeds to step S108. This is because when the elapsed stop time from stopping the compressor 11 to starting the compressor 11 is short, it is assumed that the pressure difference in the refrigeration cycle remains, so that the motor current needs to be increased. On the other hand, if it is determined in step S106 that the obtained stop duration does not fall below the threshold value 3 (NO), the process directly proceeds to step 108.

In step S108, the inverter controller 128 determines the magnitude of the motor current (positioning current and optionally synchronous current) at the initial stage of startup based on the determination results so far. In the embodiment to be described, assuming that the initial value of the stage is 0, the determination result of any one of the four stages from 0 to 3 is obtained through steps S102 to S107. In step S108, it is possible to select the corresponding stage from the preset positioning currents prepared for each stage from stage 0 to stage 3 and optionally the magnitude of the synchronization current. In this way, threshold values are set for the differential pressure between the discharge pressure and the suction pressure, the intermediate temperature of the heat exchanger, and the elapsed stop time from when the compressor is stopped until when the compressor is started. , The magnitude of the motor current at startup is adjusted step by step.

In the embodiment to be described, the judgment result is described as having one judgment condition for each of the three judgment items and having a total of four stages assuming that each judgment condition has the same score. However, the number of steps may be less than 4 or 5 or more, and the steps may be obtained by weighting and adding. In addition, a table may be prepared that holds eight ways in total depending on the authenticity of each determination result. Further, a plurality of threshold value determinations may be provided for each item of differential pressure, heat exchanger intermediate temperature and stop duration, one of the items may be excluded from the conditions, or another determination item may be provided. You may join. Further, instead of the threshold determination, the magnitude of the motor current may be determined using a function of pressure difference, intermediate temperature and stop duration.

Subsequently, this process is terminated in step S109. After that, positioning control and synchronous control are performed according to the determined magnitude of the motor current.

4 (A) and 4 (B) schematically show the time change of the current value during the positioning control and the synchronous control based on the determination of the motor drive control device 100 according to the present embodiment. The control state of the inverter (separate from positioning control and synchronous control) is indicated by double-headed arrows. In the above description, it is assumed that the determination result has four stages, but FIG. 4A shows the case where the motor current during the positioning control and the synchronous start control is the largest (all the determination conditions of the above three items are satisfied). Case) is illustrated, and FIG. 4B schematically shows the case where the motor current during the positioning control and the synchronous start control is the smallest (when all the judgment conditions of the above three items are not satisfied). .. In addition, FIG. 4 shows the time change of the current value for three phases, and the three-phase signal is identified by the solid line, the broken line, and the alternate long and short dash line.

The time change of the three-phase current during the positioning control and the synchronous control is expressed by the following equation, for example.

(Number 1)
Iu = A (t) * sin (ωt)
Iv = A (t) * sin (ωt + 120 °)
Iw = A (t) * sin (ωt + 240 °)

ω is an angular frequency, which is a function that gradually increases to a predetermined frequency during the period of synchronous control. A (t) is a function representing the amplitude of the current, and the time is within the range below the maximum current that can be passed through each phase during normal operation and within the range below the upper limit according to the above-mentioned determination result. It is a function that monotonically increases (for example, linearly increases) from 0 at 0. The rate of increase of A (t) (in the case of linear increase, the slope) can also be a value according to the above-mentioned determination result. Although A (t) is a function of time, it is uniquely determined by determining the upper limit value and the rate of increase based on the determination result in step S108 shown in FIG. Note that ωt is fixed during the positioning control period, so that the current is direct current during the positioning control period and the frequency ω (synchronous) of the amplitude A (t) during the synchronous control period. It is a function of time that increases during the control period.) It becomes an alternating current. In the example shown in FIG. 4, the ωt during the positioning control period is fixed at 90 ° for convenience of explanation. The three-phase currents are maintained in a state of being 120 ° out of phase with each other.

FIG. 4A shows the case where the maximum current is reached, and A (t) shown by the thick broken line linearly increases to the upper limit value (maximum value) during the entire positioning control period, and thereafter, synchronous control is performed. The inside is constant. On the other hand, FIG. 4B shows the case where the current is the smallest, and A (t) shown by the thick broken line increases linearly during the period of positioning control and synchronous control. In the example shown in FIG. 4 (B), A (t) is limited to a range of a lower upper limit value or less than in the case of FIG. 4 (A). However, the present invention is not limited to this, and only the rate of increase (in the case of linear increase, the slope) may be changed without changing the upper limit value.

In FIG. 4A, the peak value of the motor current during synchronous control is constant, but in FIG. 4B, the peak value of the motor current during synchronous control gradually increases. Adjusting the motor current during positioning control and synchronous control is to reduce the thermal stress given by the direct current (component), so if the frequency increases during synchronous control, the peak value of the motor current will be lowered. The need is reduced, but rather the motor current can be increased to ensure start-up stability.

The time change of the current value shown in FIG. 4 is an example, and there is an intermediate stage between FIGS. 4 (A) and 4 (B), and the rate of increase of A (t) is appropriately set according to each stage. It is possible to do. Further, although the shape of the function of A (t) has been described by using linear as an example, the shape is not limited to this, and any monotonically increasing function can be used.

5 (A) and 5 (B) are graphs plotting the time change of the current value at the time of positioning control and synchronous control in the motor drive control device according to the present embodiment and the load torque at that time. The control state of the inverter is indicated by double-headed arrows. Further, FIG. 5 shows the time change of the current of one phase as a representative.

As shown in FIGS. 4 and 5, the inverter control state starts with the positioning control, is followed by the synchronous (start) control, and further transitions to the sensorless control (normal control) as shown in FIG. During positioning control, a positioning current (direct current) is passed through the motor. That is, the polarity of the positioning current does not change. During synchronous control, an alternating current called synchronous current is passed. The frequency of this alternating current gradually increases, and the rotation speed of the compressor increases. When the rotation speed of the compressor 11 reaches a predetermined value, the process shifts to sensorless control.

During sensorless control, the phase of the motor rotor is estimated from the motor current detection value, and the load torque is estimated from the motor current detection value and the rotor phase. If the load torque can be estimated, the motor current can be adjusted to the minimum necessary value according to the load torque. On the other hand, during the positioning control and the synchronous start control at the initial stage of starting, the phase information of the rotor is not used for adjusting the motor current, and the open loop control is performed at that point. During open loop control, it is necessary to pass a sufficiently large motor current with respect to the load torque, but in the embodiment described above, the magnitude of the current value is adjusted according to the determination result representing the state of the refrigeration cycle described above. Will be done. Therefore, the motor current is adjusted to the minimum necessary value in the positioning control (further, during the synchronous start control) while avoiding the event that the motor current is too small and the motor is out of step. Therefore, it is possible to prevent the life of the inverter circuit from being shortened. In this way, by adjusting the motor current during positioning control at the initial start-up and optionally synchronous control to the smallest possible value within the range where step-out does not occur, based on the state of the refrigeration cycle at start-up, the inverter It is possible to reduce the loss of circuits and motors and improve efficiency.

As described above, FIG. 5 follows a process of performing positioning control and synchronous control and then transitioning to sensorless control, but the present invention is not necessarily limited to this. For example, the positioning control (direct current) and the synchronous control (alternating current) are not clearly separated, and the alternating current may have a small frequency (for example, a frequency of about 1 or less) even during the positioning control period. In that case, the DC component in the region where the frequency ω is close to 0 plays the role of the positioning current.

In the above-described embodiment, it is assumed that there is only one compressor 11. However, in other embodiments, a plurality of compressors 11 may be provided. When a plurality of compressors 11 are arranged in one refrigeration cycle, it is assumed that the load torque differs depending on whether the other compressors are driven or stopped. For example, when starting the compressor from the state where all the compressors are stopped and when starting the compressor when one or more other compressors are already driven, the former is the difference at the time of starting. The pressure is low and the load torque is small. Therefore, the former can set the motor current peak value during positioning control and at the start of synchronous control lower, and the latter can set the motor current peak value during positioning control and at the start of synchronous start control higher. That is, when starting the motor provided in one compressor, the state of the refrigeration cycle can be detected based on whether or not another compressor is driven, and in that case, the positioning current can be detected. May be adjusted to be larger when any of the other compressors is being driven. This determination condition may be used alone or in combination with some or all of the differential pressure, intermediate temperature and stop duration described above.

Hereinafter, preferred embodiments will be described with reference to FIGS. 6 to 8. In the above-described embodiment, the current of each phase is direct current during the positioning control, so that the phase of the motor current during the positioning control does not change. On the other hand, in a preferred embodiment described below, by further adjusting the phase of the positioning current during the positioning control, the start-up stability can be further improved even when the positioning current is reduced. Is.

As described above, the phase of the motor current during positioning control does not change. However, the phase (mechanical angle) of the motor rotor changes according to the initial phase of the rotor. FIG. 6 is a graph plotting changes in the current value over time and changes in the phase of the rotor during positioning control and synchronous control when starting from various initial phases.

Although FIG. 6 shows the initial phases (A) to (C) of the three rotors, the phases of the motor currents during the positioning control are all 0 rad (0 °). In FIG. 6A, the initial phase of the rotor is −0.87 rad (-50 °), which is delayed. Therefore, the phase of the rotor changes from −0.87 rad (-50 °) to 0 rad (0 °) during the positioning control. In FIG. 6B, the initial phase of the rotor is 0 rad (0 °), which coincides with the phase of the current. Therefore, the phase of the rotor does not change during the positioning control. In FIG. 6C, the initial phase of the rotor is 1.04 rad (+ 60 °), which is advanced. Therefore, the phase of the rotor changes from 1.04 rad (+ 60 °) to 0 rad (0 °) during the positioning control.

From the above, when the initial phase of the rotor is delayed with respect to the phase of the motor current, the phase of the rotor advances in the positive direction during the positioning control, and conversely, when the initial phase of the rotor advances, the positioning control is performed. It can be seen that the phase of the rotor advances in the negative direction. Note that FIG. 6 shows the behavior of a permanent magnet synchronous motor with a 3-pole pair, and in the case of a 3-pole pair, the amount of change in the phase of the rotor is 1/3 of the amount of phase change in the motor current. Please note.

Considering the change in the phase of the rotor and the compression of the refrigerant, when the phase of the rotor is advanced in the positive direction, load torque is generated due to the compression of the refrigerant, but on the other hand, the phase of the rotor is negative. When advancing in the direction, no load torque is generated due to the compression of the refrigerant. Therefore, the load torque is smaller when the phase of the rotor is advanced in the negative direction than in the positive direction, which means that there is more room for reducing the positioning current.

Therefore, in a preferred embodiment, the inverter controller 128 performs control so that the phase of the rotor advances in the negative direction during the positioning control regardless of the initial phase of the rotor.

The time change of the three-phase current at the time of positioning control accompanied by phase adjustment is expressed by the following equation, for example.

(Number 2)
Iu = A (t) * sin (ωt + θ (t))
Iv = A (t) * sin (ωt + 120 ° + θ (t))
Iw = A (t) * sin (ωt + 240 ° + θ (t))

Similar to the above, ω is an angular frequency, which is a function that gradually increases to a predetermined frequency during the period of synchronous control. A (t) is a function representing the amplitude of the current, and the time is within the range below the maximum current that can be passed through each phase during normal operation and within the range below the upper limit according to the above-mentioned determination result. It is a function that monotonically increases (for example, linearly increases) from 0 at 0. The rate of increase of A (t) (in the case of linear increase, the slope) can also be a value according to the above-mentioned determination result. Similar to the above-described embodiment, ωt is fixed during the positioning control period, but the phase θ (t) is added, and the phase of the three-phase currents is maintained in a state of being 120 ° out of phase with each other. However, it means that the phase changes by θ (t) even during the positioning control. Then, θ (t) becomes a function that changes to −2πrad (rotation in the reverse direction of 360 °) over the entire period of positioning control.

FIG. 7 schematically shows the time change of the current value during the positioning control and the synchronous control with the phase adjustment according to the preferred embodiment. As in FIG. 4, FIG. 7 also shows the time change of the current value for three phases, and the three-phase signal is identified by the solid line, the broken line, and the alternate long and short dash line. FIG. 8 is a graph plotting changes in the current value over time and changes in the phase of the rotor during positioning control and synchronous control with phase adjustment according to a preferred embodiment when starting from various initial phases. FIG. 8 typically shows the time variation of the one-phase current. FIG. 8 also shows the behavior of the permanent magnet synchronous motor of the 3-pole pair, and it should be noted that in the case of the 3-pole pair, the amount of change in the phase of the rotor is 1/3 with respect to the amount of phase change in the motor current. I want to be.

As shown in FIGS. 7 and 8, during the positioning control, the phase of the motor current is changed in the negative direction by 2πrad (360 °) in the electric angle. In FIG. 8A, the phase of the rotor changes from −0.87 rad (−50 °) to −2.09 rad (−120 °) during positioning control. In FIG. 8C, the phase of the rotor changes from 1.04 rad (60 °) to 0 rad during positioning control. By advancing the positioning current whose phase is fixed in the negative direction in this way, it is possible to reliably advance the phase of the rotor in the negative direction regardless of the initial phase of the rotor. Therefore, since the load torque due to the compression of the refrigerant is not generated, the load torque can be made smaller, and the positioning current can be further reduced by that amount.

As described above, according to the present disclosure, the start-up of the motor used in the refrigeration cycle is stabilized, the thermal stress on the inverter circuit applied at the time of start-up is reduced, and the fatigue and deterioration of the elements of the inverter circuit are suppressed. As a result, it becomes possible to provide a motor drive control device, a drive control method, and a refrigerating / air conditioner capable of preventing failure of a device including an inverter circuit and extending the life of the device.

In the motor drive control device, drive control method, and inverter circuit in the refrigeration and air conditioner according to the present embodiment, the current flowing at the time of starting the motor is minimized according to the state of the refrigeration cycle, and heat stress is as much as possible. It will be reduced. In particular, in a device such as a compressor of a refrigerating air conditioner, it is possible to prevent a failure of the device such as a refrigerating air conditioner and extend the life by preferably reducing the wear of the inverter circuit for driving the motor.

In the above-mentioned prior art of Patent Document 1, in the initial excitation mode in which a direct current is passed through each phase, which is performed before the synchronous operation mode, the direct current of each phase can flow to each phase at the maximum during normal operation. Only the point where the current value is gradually increased from zero in the range below the current peak value is disclosed, and the peak value during synchronous control is also controlled to be constant. On the other hand, in the control according to the present disclosure, during the period of positioning control and optionally synchronous control from the differential pressure of the discharge pressure and the suction pressure, the intermediate temperature of the heat exchanger, the stop duration, and the operating state of other compressors. By adjusting the magnitude of the current value, the starting current more suitable for the load of the compressor can be determined.

The embodiment of the present invention is not limited to the above-described embodiment, and may include various modifications. For example, the above-described embodiment has been described in detail for the sake of easy understanding, and is not necessarily limited to the one including all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

Further, some or all of the above configurations, functions, processing units, processing means and the like may be realized by hardware, for example, by designing with an integrated circuit. Furthermore, some or all of the above configurations, functions, etc. are written in legacy programming languages such as assembler, C, C ++, C #, Java (registered trademark), object-oriented programming languages, etc. Computers that realize functions This can be realized by executable programs, and information such as programs, tables, and files that realize each function can be found in HDD (Hard Disk Drive), SSD (Solid State Drive) ROM, EEPROM, EPROM, flash memory, etc. Storage device, flexible disc, CD-ROM, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, Blu-ray disc, SD (registered trademark) card, MO, etc. It can be distributed through telecommunications lines.

Further, a part or all of each of the above configurations, functions, etc. can be mounted on a programmable device (PD) such as a field programmable gate array (FPGA), and the above functional unit can be mounted on the PD. Circuit configuration data (bit stream data) to be downloaded to PD to realize the above, HDL (Hardware Description Language) for generating circuit configuration data, VHDL (Very High Speed Integrated Circuits Hardware Description Language), Verilog-HDL, etc. It can be distributed by a recording medium as the data described by. In addition, the control lines and information lines indicate what is considered necessary for explanation, and do not necessarily indicate all the control lines and information lines in the product. In practice, it can be considered that almost all configurations are interconnected. Further, the various data formats exemplified in the above description can be configured by, for example, CSV (Comma-Separated Values), XML (eXtensible Markup Language), binary (binary), etc., but are not necessarily limited to these. It's not a thing.

1 ... air conditioner, Q ... refrigerant circuit, 10 ... outdoor unit, 11 ... compressor, 12 ... accumulator, 13 ... outdoor heat exchanger, 14 ... outdoor fan, 15 ... four-way valve, 18a ... gas stop valve, 18b ... Liquid blocking valve, 19a ... Suction pressure sensor, 19b ... Discharge pressure sensor, 19c ... Discharge temperature sensor, 19d ... Temperature sensor, 19g ... Outside air temperature sensor, 19h ... Outdoor heat exchanger intermediate temperature sensor, 20 ... Indoor unit, 21 ... Indoor expansion valve, 22 ... Indoor heat exchanger, 23 ... Indoor fan, 24 ... Indoor electromagnetic valve, 25 ... Indoor heat exchanger intermediate temperature sensor, 30 ... Control device, 100 ... Motor drive control device 100, 101 ... AC power supply, 102 ... motor, 110 ... converter unit, 111 ... rectifying circuit, 112 ... diode, 113 ... smoothing reactor, 114 ... smoothing capacitor, 120 ... inverter unit, 121 ... DC voltage detection unit, 122 ... inverter circuit, 123 ... semiconductor switching element , 124 ... Diode, 125, 126 ... Current sensor, 127 ... Gate drive circuit, 128 ... Inverter controller

Claims (10)

A drive control device that controls the motor used in the refrigeration cycle.
An inverter circuit connected to the motor and a control unit that controls the inverter circuit so that a positioning current for fixing or adjusting the position of the rotor of the motor is passed through the motor when the motor is started. , A drive control device including a control unit that adjusts the magnitude of the positioning current according to the state of the refrigeration cycle. The control unit controls the inverter circuit so that the positioning current is passed for a predetermined period and then changed to an alternating current to allow the synchronous current to flow to the motor, and the magnitude of the synchronous current is increased according to the state of the refrigeration cycle. The drive control device according to claim 1, further adjusting the current. The motor is provided in the compressor, the state of the refrigeration cycle is detected based on the differential pressure of the discharge pressure and the suction pressure of the compressor, and the positioning current is increased when the differential pressure is large. The drive control device according to claim 1 or 2, which is adjusted to the above. The motor is provided in a compressor connected to a heat exchanger, and the state of the refrigeration cycle is detected based on the temperature of the heat exchanger and the elapsed stop time from stopping the compressor to starting it. The drive control device according to any one of claims 1 to 3, wherein the positioning current is adjusted to have a magnitude corresponding to the temperature, the elapsed stop time, or both of them. The motor is provided in the compressor, a plurality of the compressors are provided, and when the motor provided in one compressor is started, the state of the refrigeration cycle is driven by any of the other compressors. The drive control device according to any one of claims 1 to 4, which is detected based on whether or not the compressor is used, and the positioning current is adjusted to be large when the other compressor is being driven. .. The control unit is characterized in that when the motor is started, the phase of the rotor of the motor is advanced in the opposite direction by at least one electric angle within the period in which the positioning current is passed, and then the forward rotation is started. The drive control device according to any one of claims 1 to 5. The drive control device according to any one of claims 1 to 6, wherein the motor is a permanent magnet synchronous motor. With a heat exchanger,
A compressor with a motor and
The inverter circuit connected to the motor and
The inverter circuit includes a control unit that controls the inverter circuit, and the control unit causes the inverter circuit to pass a positioning current for fixing or adjusting the position of the rotor of the motor to the motor when the motor is started. A refrigerating air conditioner, characterized in that the magnitude of the positioning current is determined according to the state of the refrigerating cycle. The refrigerating air conditioner further
Discharge pressure sensor that detects the discharge pressure of the compressor, suction pressure sensor that detects the suction pressure of the compressor, temperature sensor that detects the temperature of the heat exchanger, from stopping the compressor to starting it. The state of the refrigeration cycle is detected based on the at least one means, including at least one means selected from the group consisting of a means for measuring the elapsed stop time and a means for detecting the drive state of another compressor. The refrigerating air conditioner according to claim 8. A drive control method that controls the motor used in the refrigeration cycle.
A step of determining the magnitude of the positioning current to be passed to fix or adjust the position of the rotor of the motor according to the state of the refrigeration cycle, and
A drive control method comprising the step of controlling an inverter circuit connected to the motor so that the positioning current flows through the motor according to the determined magnitude when the motor is started.

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