JP4200885B2 - Motor drive device for electric compressor - Google Patents

Description

  The present invention relates to an electric compressor motor drive device for driving an electric compressor including a compression mechanism and a motor for driving the compression mechanism.

Conventionally, what is indicated by patent documents 1 is known as a protection device of motor drive devices, such as an inverter, in an inverter integrated electric compressor. In this prior art, a motor housing cooled by suction refrigerant is attached with a heat-generating component that generates heat during operation, such as a power device that drives the motor, and the temperature of this heat-generating component is detected and protected. The operation is performed. As a protection operation, when the temperature of the exothermic component exceeds a predetermined value, the motor is operated even when the temperature of the exothermic component rises by increasing the number of revolutions of the motor to increase the cooling effect of the suction refrigerant. Without stopping, the temperature of the heat-generating component is lowered and the motor driving device is continuously operated.
JP 2003-139069 A

  However, in the prior art, the motor drive device can be protected by cooling the heat-generating component among the heat-generating components provided in the motor drive device and the other non-heat-generating components that generate a small amount of heat. The protection against non-heat-generating parts was insufficient. For this reason, the non-heat-generating component may malfunction and lead to malfunction of the motor drive device itself.

  Here, the non-heat-generating component in the motor drive device is a component other than a heat-generating component such as a power device that drives the motor, and the motor generates less heat (power consumption or loss) than the power device. Elements or components such as a photocoupler, CPU, internal power supply circuit, and communication circuit on the control circuit of the driving device. Furthermore, among these non-heat-generating components, the photocoupler is an element that hardly generates heat and has the lowest heat resistance.

  That is, the exothermic parts used in the motor drive device of the electric compressor are normally arranged so as to be able to exchange heat with the motor housing cooled by the suction refrigerant, and the cooling effect by the suction refrigerant during motor operation is exhibited. The temperature rise of the exothermic component is suppressed. On the other hand, non-heat-generating components that generate a small amount of heat during operation are usually arranged on an electronic circuit board to form a control circuit for a motor drive device. The electronic circuit board is placed in a state where there is almost no heat exchange with the suction refrigerant and the heat-generating parts, and the non-heat-generation parts also have little heat exchange with the suction refrigerant and the heat-generation parts. Furthermore, the operation guarantee temperature and the storage guarantee temperature of the non-heat-generating parts are designed to be lower than the operation guarantee temperature and the storage guarantee temperature of the exothermic parts. Note that the guaranteed operating temperature refers to the upper limit of the ambient temperature range that allows normal operation without impairing the function of the component (or element). The guaranteed storage temperature refers to a state where the component (or element) is not operated. This is the upper limit of the ambient temperature range that can be stored, and is designed to be higher than the guaranteed operating temperature. In other words, if the temperature of the element exceeds the guaranteed operating temperature while the element is operating, or if the temperature of the element exceeds the guaranteed storage temperature while the element is not operating, the element will not function normally and the element will return to a low temperature. However, it will be in a damaged state that does not function properly.

  Therefore, in the conventional technology, even when the motor is operated and the refrigerant is sucked into the motor housing and the heat-generating component is cooled, for example, the atmosphere is affected by the heat in the engine room where the motor driving device is disposed. When the temperature rises, the heat from this atmosphere causes the temperature of the non-exothermic components that are difficult to exchange heat with the suction refrigerant to rise, exceeding the guaranteed operating temperature and the guaranteed storage temperature of the non-exothermic components. For this reason, the reliability of the non-heat-generating component is lowered, and the non-heat-generating component may be damaged.

  Furthermore, after the motor is stopped, the possibility of damage to the non-heat-generating parts increases. That is, after the motor is stopped, the temperature of the heat-generating component that easily exchanges heat with the suction refrigerant and the motor housing gradually increases with a first order delay due to the heat capacity of the suction refrigerant and the motor housing. At this time, since the degree of temperature rise of the heat-generating component is small, refrigerant suction for cooling is not performed in the prior art. However, since it is difficult for the non-heat-generating component to exchange heat with the motor housing, the temperature rises almost coincident with the rise in ambient temperature. Due to the heat from this atmosphere, the temperature of the non-heat-generating component rises above the operation guarantee temperature, and the operation reliability may be impaired. In particular, among the non-heat-generating parts, the photocoupler generates little heat and has the lowest heat resistance, so it is most susceptible to heat (heat damage) from the heat and atmosphere generated by the heat-generating parts, and the reliability of the motor drive device It was a hindrance to improvement in sex.

  In view of the above points, an object of the present invention is to improve the reliability of a motor drive device by protecting the temperature of non-heat-generating components included in the motor drive device of an electric compressor.

In order to achieve the above object, according to the first aspect of the present invention, a compression mechanism (11) for sucking and compressing refrigerant, an electric motor (12) for driving the compression mechanism, and a motor drive device (13) for driving and controlling the electric motor. An electric compressor (10), wherein the motor driving device is arranged so as to be able to exchange heat with the sucked refrigerant, and generates heat in response to the operation of the electric motor; Non-exothermic components (4, 5, 7a, 8, 61), temperature detecting means (7b) for detecting the temperature of the non-exothermic components, and motor drive based on the detected temperature of the non-exothermic components A protection control unit (5, 9) that performs protection control of the device, and the protection control unit is non-exothermic when the detected temperature of the non-exothermic component exceeds a predetermined temperature set in advance. It is characterized in that the power supply to the parts is cut off .

  According to the present invention, the temperature of the non-heat-generating component that is a component other than the heat-generating component that generates heat when the electric motor is operated is detected, and the protection control of the motor drive device is performed based on the temperature of the non-heat-generating component. Even when the electric motor is stopped, protection control of the motor drive device can be performed against the temperature rise of the non-heat generating component, and the reliability of the motor drive device can be improved.

In addition, according to the present invention, when the temperature of the non-heat-generating component rises above a predetermined temperature, the power supply to the non-heat-generating component is cut off. Therefore, the reliability of the non-heat-generating component against temperature rise can be ensured.

In the invention according to claim 2, the protection control unit turns off the electric motor when the temperature of the detected non-heat generating component exceeds a predetermined temperature when the electric motor is in a stopped state. It is characterized by being driven.

According to the present invention, when the temperature of the non-heat-generating component rises above a predetermined temperature, the electric motor in a stopped state is driven. Done. With this suction refrigerant, the exothermic component is cooled, the heat transferred from the exothermic component to the non-exothermic component can be reduced, and the heat resistance performance of the non-exothermic component can be improved.

That is, conventionally, in order to enable temperature protection even when the electric motor is stopped and the circulation of the suction refrigerant is stopped, it is necessary to cool the motor driving device as much as possible. It was.

However, in the present invention, even if the electric motor is stopped, the temperature rise of the non-heat-generating component is monitored and the electric motor is driven based on this, so that it is possible to prevent forced cooling more than necessary. This makes it possible to save energy and reduce noise.

According to a third aspect of the present invention, the temperature detecting means detects the temperature of the exothermic component, and the protection control unit detects the temperature of the electric motor when the detected temperature of the exothermic component exceeds a predetermined temperature. The rotational speed is increased by a predetermined amount.

According to the present invention, fine protection control is possible by performing in parallel the protection control against the temperature rise of the non-heat-generating component and the protection control against the temperature rise of the heat-generating component, that is, the increase in the rotation speed of the electric motor. It is effective in terms of energy saving and low noise in the operation of the electric motor.

The heat-generating component can be a power device (20) that drives an electric motor.

Further, the non-heat-generating component includes the photocoupler (7a, 61), the internal power supply circuit (4), the CPU (5), the temperature detection circuit (7b), and the communication circuit (8). It can be at least one of them.

Further, as described in claim 6, the non-heat-generating component can be a component having the lowest heat resistance among the components constituting the motor driving device. The heat resistance performance is usually evaluated by the guaranteed operation temperature or the guaranteed storage temperature, and the low heat resistance performance means that the guaranteed operation temperature or the guaranteed storage temperature is low. Therefore, if protection control is performed according to the temperature of the non-heat-generating component having the lowest heat resistance performance, protection control can be performed on all the components constituting the motor drive device, further improving the reliability of the motor drive device. Can be improved.

According to a seventh aspect of the present invention, the protection control unit increases the rotational speed of the electric motor by a predetermined amount when the detected temperature of the non-heat-generating component exceeds a predetermined temperature set in advance. Features.

According to the present invention, when the temperature of the non-heat-generating component rises above a predetermined temperature, the number of rotations of the electric motor is increased by a predetermined amount, so that the amount of refrigerant sucked increases as the rotation of the electric motor increases. This suction refrigerant increases the cooling effect on the exothermic component, so that the reliability of the exothermic component can be improved. In addition, due to an increase in the cooling effect on the heat-generating component, heat transferred from the heat-generating component to the non-heat-generating component can be reduced, and the heat resistance performance of the non-heat-generating component can be improved.

In the conventional temperature detection of the exothermic component, since the exothermic component is directly cooled by the refrigerant, the temperature of the exothermic component completely depends on the temperature of the intake refrigerant, and is caused by the temperature rise of the outside air atmosphere. The effect on non-heat-generating parts could not be determined. However, the temperature of non-heat-generating parts with low heat resistance reflects the influence of both the cooling effect of the suction refrigerant and the heat from the outside atmosphere, and this temperature is detected to protect the temperature as in the present invention. By using it, the reliability of the motor drive device can be improved.

  In addition, the code | symbol in the bracket | parenthesis of each said means shows the correspondence with the specific means as described in embodiment mentioned later.

  Embodiments of the present invention will be described below with reference to the drawings. The present embodiment is applied to an electric compressor of an in-vehicle air conditioner mounted on a hybrid vehicle or the like. FIG. 1 is a schematic diagram of a vapor compression refrigerator using an electric compressor 10 with an integrated motor driving device 10 (hereinafter referred to as an electric compressor) according to the present embodiment. Moreover, FIG. 2 is a figure which shows the arrangement | positioning condition in the engine room at the time of vehicle mounting of the electric compressor 10. FIG. FIG. 3 is a schematic configuration diagram of the motor drive device. FIG. 4 is a diagram showing the configuration of the gate driver circuit.

  As is well known, the vapor compression refrigerator has a radiator 14 that cools the compressed high-pressure and high-temperature refrigerant, a decompressor 15 that decompresses the cooled high-pressure refrigerant, and evaporates the decompressed low-pressure refrigerant. It consists of an evaporator 16 that exhibits refrigeration capacity, a gas-liquid separator 17 that stores excess refrigerant in the refrigerator as a liquid-phase refrigerant, and the like.

  In the present embodiment, as the decompressor 15, a temperature type expansion valve that controls the throttle opening degree so that the degree of refrigerant superheating on the refrigerant outlet side of the evaporator 16 becomes a predetermined value is adopted, and the gas-liquid separator 17 is used. A receiver installed on the refrigerant inlet side of the decompressor 15 is employed.

  The electric compressor 10 includes a scroll type compression mechanism 11 that sucks and compresses refrigerant, a DC brushless type electric motor 12 that drives the compression mechanism 11, an inverter 13 as a motor driving device that drives the electric motor 12, and the like. Therefore, the compression mechanism 11 and the electric motor 12 are integrated coaxially and in series.

  As shown in FIG. 2, the electric compressor 10 is located in the engine room so that the inverter 13 is positioned on the opposite side of the electric power generation / traveling engine 101 and the exhaust manifold 102 with the electric motor 12 interposed therebetween, and The vehicle body is fixed with bolts so as to face the radiator condenser 104 and the electric fan 103 in front of the vehicle.

  Therefore, the inverter 13 is exposed to exhaust heat from the engine 101, the exhaust manifold 102, the radiator condenser 104, the electric fan 103, etc., and at least the casing 13a of the inverter 13 reaches a high temperature of 100 ° C. or higher during normal traveling. For this reason, it is necessary to improve the reliability of the motor drive device (inverter) by lowering the temperature of each circuit element of the inverter 13 accommodated in the casing 13a to a temperature at which normal operation is possible.

  The inverter 13 is housed in a casing 13a as shown in a partial sectional view in FIG. The casing 13 a is assembled with the compression mechanism 11 and the electric motor 12 by being assembled with bolts on the outer cylindrical surface side of the substantially cylindrical motor housing 12 a in which the electric motor 12 is accommodated.

  The IGBT 20, which is a power device constituting the inverter 13, is fixed on the motor housing 12a so as to be able to exchange heat with the motor housing 12a. Further, the circuit board 21 of the inverter 13 is coupled to the motor housing 12 a via the insulator support member 22 and is electrically connected to the IGBT 20.

  On the surface of the circuit board 21 on the motor housing 12a side, a thermistor of a photocoupler 7a as a non-heat-generating component which is a circuit component of the inverter 13 and a temperature detection circuit 7b for detecting the temperature of the photocoupler 7a, which will be described later. Circuit components and elements (not shown in FIG. 1) of the inverter 13 including 70 are arranged so as to minimize the influence of exhaust heat from the engine or the like. The thermistor 70 is arranged at a position where a temperature correlation can be directly obtained with the photocoupler 7a to be measured. In the present embodiment, the thermistor 70 is disposed in the vicinity of the photocoupler 7 a on the circuit board 21.

  Thus, in the present embodiment, the temperature of the photocoupler 7a is detected as a non-heat-generating component that is disposed at a position where heat resistance is the lowest among the components constituting the inverter 13 and heat exchange directly with the suction refrigerant is difficult. Like to do.

  In the present embodiment, the motor housing 12 is all made of an aluminum alloy so as to increase the efficiency of heat exchange with the inverter 13.

  For this reason, in the present embodiment, the refrigerant flowing out of the evaporator 16 and sucked into the electric compressor 10 first flows in the motor housing 12a to cool the electric motor 12 and the inverter 13, and then enters the compression mechanism 11. It is configured to be sucked and compressed and to flow into the radiator 14. Therefore, the refrigerant sucked into the motor housing 12a can directly exchange heat with the IGBT 20 that is a heat generating component of the inverter 13 through the motor housing 12a made of aluminum alloy. Thus, while the electric motor 12 is rotating, the suction refrigerant flows in the motor housing 12a, efficiently cools the IGBT 20, suppresses the temperature increase of the IGBT 20, and improves the reliability of the inverter 13. be able to.

  In addition, the circuit board 21 and the circuit components on the circuit board 21 cannot directly exchange heat with the motor housing 12a and the suction refrigerant. However, when the temperature of the suction refrigerant is low due to the operation of the electric motor 12, the circulation state is continued. The space in which the circuit board 21 is housed between the motor housing 12a and the casing 13a is also cooled. Thereby, the influence of the heat of an atmosphere can be made small, the temperature rise of the circuit components (element) on the circuit board 21 can be suppressed, and the reliability of the inverter 13 can be improved.

  An air conditioning control circuit (hereinafter referred to as ECU) 9 of the air conditioner 100 is configured by a computer. The ECU 9 receives an air conditioning request signal and various signals representing environmental conditions for air conditioning, and based on these signals, the target temperature in the air conditioning and the target rotational speed of the compression mechanism 11 necessary to realize the target temperature. That is, the target rotational speed N of the electric motor 12 is calculated, and further, a command value signal that can be processed by the inverter 13 is calculated and output to the inverter 13. The ECU 9 is operated by a normal low voltage battery 9a (for example, VBL = 12V). The low voltage battery 9a is body earth.

  The inverter 13 includes a switching circuit 2 and a control circuit 3. The switching circuit 2 includes six IGBTs 20, and each IGBT 20 is ON / OFF controlled by the gate driver circuit 6. The switching circuit 2 is connected to the high voltage battery 1 and converts a DC high voltage (for example, VHB = 288V) from the high voltage battery 1 into a three-phase AC voltage by ON / OFF control of the IGBT 20. By applying a three-phase AC voltage to the electric motor 12, the electric motor 12 is rotated at a desired rotation speed N. Thereby, the compression mechanism 11 that rotates coaxially with the electric motor 12 can suck and compress the refrigerant. The high voltage battery 1 has a closed circuit configuration that is electrically floated from the body to prevent an electric shock, and is not a common ground with the body. Further, a smoothing capacitor 1a for smoothing the power supply is provided at the high voltage input terminal of the switching circuit 2.

  The control circuit 3 includes an internal power supply circuit 4, a central processing element (hereinafter referred to as CPU) 5, a gate driver circuit 6, a photocoupler 7a, a temperature detection circuit 7b, and a communication circuit 8. The internal power supply circuit 4 generates 15V as the first voltage from the high voltage VBH, and further generates 5V as the second voltage from the first voltage. The first voltage (15 V) is supplied as operating power to other analog circuits such as the gate driver circuit 6 that drives the gate of the IGBT 20, and the second voltage (5 V) is supplied to the digital circuit such as the CPU 5. Supplied as operating power.

  The CPU 5 inputs a command value signal corresponding to the target rotational speed of the compression mechanism 11 from the ECU 9, that is, the target rotational speed N of the electric motor 12, via the communication circuit 8 and the photocoupler 7a, and performs switching based on the command value signal. An ON / OFF timing signal of each IGBT 20 in the circuit 2 is calculated and output to the gate driver circuit 6. Further, the temperature detection circuit 7b is connected to the CPU 5, and a signal indicating the temperature Tph of the photocoupler 7a detected by the thermistor 70 is input from the temperature detection circuit 7b.

  Further, the CPU 5 executes processing of a control routine for protecting the temperature of the motor drive device described later based on each input signal.

  The gate driver circuit 6 drives the gate of each IGBT 20 on and off based on the timing signal. FIG. 4 shows an outline of a circuit configuration for generating a gate drive signal for one IGBT 20 of the gate driver circuit 6. A timing signal from the CPU 5 operating at the first voltage (5V) is converted into an input signal of the amplifier 62 operating at the second voltage (15V) by the photocoupler 61. The timing signal amplified by the amplifier 62 is amplified in power by the push-pull output circuit 63 and is output to one IGBT 20 as a gate signal. Thereby, each IGBT 20 is ON-OFF controlled at a desired timing to rotate the electric motor 12 at the target rotational speed N.

  In the control circuit 3, the internal power supply circuit 4, the CPU 5, the gate driver circuit 6, and the temperature detection circuit 7b are at a potential (high voltage system) based on the high voltage VBH. On the other hand, both the communication circuit 8 and the ECU 9 are at a potential (low voltage system) based on the low voltage VBL, and the communication circuit 8 is in the low voltage system, and transmits and receives signals to and from the ECU 9.

  The photocoupler 7a has an insulating structure made of an optical semiconductor and operates when supplied with power from the internal power supply circuit 4. As described above, since the high-voltage battery 1 and the low-voltage battery 9a are not connected to a common ground, the photocoupler 7a allows the high-voltage CPU 5 and the low-voltage communication circuit. Signals are transmitted to and received from 8.

  In the inverter 13 as the motor driving apparatus configured as described above, the IGBT 20 that is a power device corresponds to a heat-generating component that generates heat when it is operating, that is, when the electric motor 12 is being driven.

  On the other hand, the photocouplers 7a and 61 correspond to non-heat-generating components that hardly generate heat even during operation. The internal power supply circuit 4, the CPU 5, the temperature detection circuit 7b, and the communication circuit 8 are elements or parts that do not generate a large amount of heat, such as a power device, although they generate heat during operation. The power supply circuit 4, the CPU 5, the temperature detection circuit 7b, and the communication circuit 8 can also be considered as non-heat-generating components.

  Furthermore, circuit components are generally designed with a guaranteed operating temperature and a guaranteed storage temperature. In other words, the guaranteed operating temperature is the upper limit of the ambient temperature range that allows normal operation without impairing the function of the component (or element), and the guaranteed storage temperature is the state in which the component (or element) is not operated. This is the upper limit of the ambient temperature range that can be stored, and is designed to be higher than the guaranteed operating temperature. In other words, if the temperature of the element exceeds the guaranteed operating temperature while the element is operating, or if the temperature of the element exceeds the guaranteed storage temperature while the element is not operating, the element will not function normally and the element will return to a low temperature. However, it will be in a damaged state that does not function properly.

  In general, the guaranteed operating temperature and the guaranteed storage temperature of the heat-generating component (element) are higher than the guaranteed operating temperature and the guaranteed storage temperature of the non-heat-generating component (element).

  As described above, the IGBT 20, which is a power device as a heat-generating component, also directly exchanges heat with the suction refrigerant and the motor housing 12a in the prior art. Therefore, during operation of the IBGT 20, that is, the electric motor 12 rotates. When the motor housing 12a is in use, it is cooled by the refrigerant sucked into the motor housing 12a, and the temperature rise due to the self-heating of the heat-generating parts is alleviated, and the reliability as the motor driving device is improved.

  However, there are the following problems that are difficult to solve with the prior art. This will be described with reference to FIGS. In the figure, Tat is the ambient temperature of the casing 13a and its vicinity, Tph is the temperature of the photocoupler 7a (61) as a non-heat-generating component disposed on the circuit board 21, and Tph1 is the operation of the non-heat-generating component. Guaranteed temperature, Tph2 is the guaranteed storage temperature of the non-exothermic component, Td is the temperature of the IGBT 20 as the exothermic component arranged so as to be able to exchange heat with the motor housing 12a, Td1 is the guaranteed operation temperature of the exothermic component, and Tph1 < Td1 <Tph2.

  FIG. 7 shows the temperature transition of each part from the time when the electric motor 12 in the stopped state starts rotating. As the electric motor 12 starts to rotate, the temperature Td of the heat-generating component such as the power device decreases due to the cooling effect by the suction refrigerant, and a constant temperature is maintained in the thermal equilibrium state. At this time, when the rotation speed of the electric motor 12 is small, and therefore the temperature of the suction refrigerant is relatively high and the flow rate of the circulating refrigerant is small, the cooling effect by the suction refrigerant is sufficient to ensure the reliability of the power device. However, the non-heat-generating component on the circuit board 21 that is not directly cooled by the suction refrigerant has a greater heat generation effect of the power device than the indirect cooling effect by the suction refrigerant. Further, due to the influence of heat from the outside air atmosphere due to the rise in the outside air atmosphere temperature Tat, the temperature Tph of the non-heat-generating component rises, and there is a case where a heat equilibrium state is reached when the temperature exceeds a relatively low guaranteed operating temperature Tph1. In this case, the non-heat-generating component is thermally damaged and reliability cannot be ensured.

  Furthermore, when the electric motor 12 is stopped because the air conditioner 100 is not used, the non-heat-generating component is placed in a thermally severe state as follows.

  FIG. 8 shows how the temperature of each part changes due to the influence of exhaust heat from the engine and the like from the time when the electric motor 12 is in a stopped state and Tat≈Tph≈Td. As time elapses, the temperature Tph of the non-heat-generating component on the circuit board 21 increases while maintaining the relationship of Tph≈Tat as the ambient air temperature Tat increases. On the other hand, the heat-generating component causes a first-order delay in the rise of the temperature Td according to the heat capacity of the motor housing 12a for heat exchange. For this reason, the non-heat-generating component rises to a temperature exceeding the operation guarantee temperature Tph1 earlier than the heat-generating component, and is thermally damaged.

  Usually, the components and elements arranged on the circuit board 21 operate even when the electric motor 12 is stopped, such as the internal power supply circuit 4, the CPU 5, the photocoupler 7 a, the temperature detection circuit 7 b, and the communication circuit 8. The majority of things. The components and elements arranged on the circuit board 21 include a large number of non-heat generating components. For this reason, components such as non-exothermic components and elements on the circuit board 21 that are not in direct heat exchange with the suction refrigerant are damaged by heat prior to the exothermic components. The problem arises that the operational reliability of the system is impaired.

  Next, a temperature protection control routine in the present embodiment for solving the above problem will be described with reference to the flowchart of FIG. FIG. 5 shows a processing procedure of a computer program in which the CPU 5 as the protection control unit performs processing repeatedly at predetermined time intervals.

  The CPU 5 sets a state as shown in FIG. 6 according to the temperature Tph of the photocoupler 7a detected by the thermistor 70. In FIG. 6, the relationship between the temperatures is T1 <T2 <T3≈Tph1. That is, the CPU 5 monitors the change state of the temperature Tph of the non-heat generating element, which is a detection signal from the temperature detection circuit 7b. When the detection temperature Tph rises, the CPU 5 sets the normal state when Tph is less than T2, and the self-shutoff signal: None. , Overheat signal: None. Further, when the temperature Tph rises and T2 ≦ Tph <T3, the alarm state is set as the self-shutoff signal: none and the overheat signal: yes. Further, when the temperature Tph rises and T3 ≦ Tph, an abnormal state is assumed and the self-cutoff signal is set to “present”. Further, if Tph falls below T1 from the alarm state (with an overheat signal), it is determined that the normal state has been restored, and the overheat signal is canceled. For the purpose of preventing hunting when the temperature Tph rises and falls near the threshold temperatures T1 and T2, hysteresis of the alarm state occurrence T2 and the alarm state release T1 is provided.

  At the start time, before the operation of the air conditioner 100 is started, that is, the electric motor 12 is in a stopped state. First, in step S100, the presence / absence of a self-interruption signal is determined. If yes, that is, if it is determined that there is an abnormal state, Tph is equal to or greater than Tph1, and therefore, in step S102, self-interruption is performed. Stop processing based on the flow.

  In this self-interruption, the CPU 5 issues a command signal to the internal power supply circuit 4 so as to shut off (suppress energization) the power supply to at least the photocoupler 7a to be measured. In this case, energization may be stopped at the same time for non-heat-generating components other than the photocoupler 7a, for example, the internal power supply circuit 4, the CPU 5, the temperature detection circuit 7b, the communication circuit 8, and the like.

  With this self-interruption, the non-heat-generating component that has been de-energized can be increased in temperature margin from the guaranteed operating temperature to the guaranteed storage temperature, and thus can be less susceptible to thermal damage as an element. Therefore, when the air conditioner 100 is operated again when the external ambient temperature Tat is lowered to the operation guarantee temperature or lower, the inverter 13 can be normally operated as a motor drive device.

  If there is no self-blocking signal in step S100, it is determined in step S104 whether there is a normal activation signal for the air conditioner 100. Specifically, this normal activation signal is a signal for instructing the target rotational speed N to the electric motor 12 calculated by the ECU 9 in the normal operating state of the air conditioner 100.

  If it is determined in step S104 that the normal activation signal is present, the process proceeds to the normal operation mode, and the electric motor 12 is activated or driven in step S106. If it is determined in step S104 that there is no normal activation signal, the process proceeds to the forced drive mode (step S122).

  In the normal operation mode, after the electric motor 12 is started or driven, the mode shifts to the motor rotation speed control mode based on the target rotation speed N. First, in step S108, the presence or absence of the self-cutoff signal is determined as in step S100. . When it is determined that the self-blocking signal is present, the self-blocking is performed in step S110 as in step S102, and this control flow is terminated.

  If it is determined that there is no self-interruption signal, the presence or absence of an overheat signal is then determined in step S112. If it is determined that there is an overheat signal, that is, an alarm state is present, Tph is lower than the guaranteed operating temperature Tph1 (T3≈Tph1> Tph> T2 or T1), that is, within the guaranteed operating temperature range. The temperature is close to the upper limit. Therefore, if this state continues, the temperature Tph of the non-exothermic component may exceed the operation guarantee temperature Tph1 due to the influence of the heat of the outside atmosphere or the heat generated by the exothermic component. In order to increase the cooling effect by the sucked refrigerant, the rotational speed of the electric motor 12 is increased.

  That is, in step S116, the current target rotational speed N of the electric motor 12 is increased by the rotational speed n, and the electric motor 12 is controlled to rotate based on the new target rotational speed N + n. The increment n is a rotational speed sufficient to lower the temperature Tph of the non-heat generating component in the range of T1 <Tph <T2 to the range of Tph <T1, and is set in advance.

  On the other hand, if it is determined in step S112 that there is no overheat signal, it is determined in step S108 that there is no self-interruption signal, so that the normal state is determined from FIG. 6, and the process proceeds to step S114. In step S114, the electric motor 12 is rotationally controlled based on the current target rotational speed N.

  Next, in step S118, the presence / absence of a stop signal is determined. The case where there is no stop signal is a state where the target rotational speed N is being output from the ECU 9, and at this time, the process returns to step S108 and the process is repeated. The case where the stop signal is present is a case where the switch (so-called A / C switch) of the air conditioner 100 is in the off state, the ignition off state, and the target rotational speed N = 0 calculated by the ECU 9, at this time in step S120. The operation of the electric motor 12 is stopped, the routine of the normal operation mode is exited, and the process proceeds to step S122.

In step S122, the presence or absence of an overheat signal is determined based on the same determination criteria as in step S112 as the forced drive mode. If it is determined that there is no overheat signal, the process returns to step S100 and the process of the control routine is repeated. If it is determined that the overheat signal is present, the stopped electric motor 12 is forcibly started (step S124), and its rotation is increased to a predetermined rotation speed n (0 → n) (step S126). As a result, the compression mechanism 11 is activated to circulate the suction refrigerant into the motor housing 12a, and the temperature Td of the exothermic component is lowered by starting cooling and continuing cooling of the exothermic component that directly exchanges heat with the suction refrigerant. In addition, the cooling of the non-exothermic components that do not directly exchange heat with the suction refrigerant can be gradually advanced.

  That is, in the forced drive mode, even when the electric motor 12 is stopped, the temperature Tph of the non-heat-generating component having the lowest heat resistance exceeds the temperature T2 (<T3≈Tph1) close to the operation guarantee temperature Tph1. At the time, the electric motor 12 is forcibly started and the rotation control at the rotation speed n is performed. Thereby, the temperature rise of a non-heat-generating component can be suppressed under the influence of the cooling effect of the motor housing 12a and the heat-generating component by the suction refrigerant, and the reliability of the motor drive device can be improved.

  Conventionally, the cooling effect is increased in accordance with the temperature of the heat-generating component, so that the temperature of the motor drive device can be protected even if the electric motor stops and the circulation of the suction refrigerant stops. Therefore, it is necessary to cool the motor driving device as much as possible, and the electric motor is driven extra. However, in this embodiment, even when the electric motor 12 is stopped, the temperature rise of the non-heat-generating component (photocoupler 7a) is monitored and the electric motor 12 is driven based on this, so that forced cooling is performed more than necessary. This can save energy and reduce noise.

  As described above, in the present embodiment, the temperature Tph of the photocoupler 7a having the lowest heat resistance among non-heat-generating components arranged in a state in which direct heat exchange with the suction refrigerant is difficult is detected, and this temperature Tph is detected. Protection control is performed in response to the rise of. Specifically, when the temperature Tph of the photocoupler 7a exceeds a predetermined temperature T2 lower than the operation guarantee temperature Tph1, the target rotational speed N (including N = 0) of the electric motor 12 is forcibly set from the current value. Since the amount is increased by a fixed amount n, the amount of refrigerant sucked into the motor housing 12a is increased, thereby improving the cooling effect of the IGBT 20, which is a heat-generating component capable of directly exchanging heat with the sucked refrigerant, and improving the reliability of the inverter 13. Can be improved. That is, the reliability of the inverter 13 can be improved in both the stopped state (N = 0) and the activated state (N> 0) of the electric motor 12.

  When the temperature Tph of the photocoupler 7a further rises and exceeds the temperature T3 in the vicinity of the operation guarantee temperature Tph2, the non-heat-generating component is turned off and the component and the element are stored. As a result, the heat-resistant temperature margin can be increased from the guaranteed operating temperature to the guaranteed storage temperature even when the temperature of the non-exothermic component rises in a high-temperature atmosphere for a non-exothermic component that has been turned off. Thermal damage to the element can be avoided.

  Moreover, since the photocoupler 7a is a non-heat-generating component having the lowest heat resistance, the reliability of the entire inverter 13 can be improved by performing protection control according to the temperature of the photocoupler 7a.

(Other embodiments)
The above embodiment can be modified in various ways as follows.
(1) In the above embodiment, the temperature of the photocoupler 7a having the lowest heat resistance as the non-heat-generating component is detected, but the present invention is not limited to this. For example, the thermistor 70 is arranged in the vicinity of at least one of the internal power supply circuit 4, the CPU 5, the temperature detection circuit 7b, the communication circuit 8, and the like as a non-heat generating component arranged on the circuit board 21, thereby The detected temperature may be the temperature of the non-heat-generating component.
(2) In the above embodiment, the inverter 13 as the motor driving device is attached to the motor housing 12a, and the IGBT 20 which is a heat generating element in the inverter 13 is made to exchange heat with the suction refrigerant via the motor housing 12a. However, the mounting position of the inverter 13 is not limited to this. For example, the inverter 13 may be attached to the suction pipe to the electric motor 12 so that the IGBT 20 exchanges heat with the suction refrigerant through the suction pipe.
(3) In the above embodiment, the increase in the number of rotations of the electric motor 12 in the presence of the overheat signal (steps S116 and S122 in FIG. 5) is performed by the preset increase amount n, but is not limited thereto. For example, an increment Δn every predetermined time may be provided, and the number of rotations of the electric motor 12 may be increased stepwise every predetermined time. At this time, in the stepwise increase process, if the temperature Tph decreases and the overheat signal disappears, the rotation speed increase control stops, and the rotation speed can be decreased to the original target rotation speed N (step S114). ). Thereby, compared with the case where a rotation speed is increased in steps, the energy consumption and generated noise of the electric motor 12 can be reduced.
(4) Although the temperature protection control routine shown in FIG. 5 is executed by the CPU 5 in the above embodiment, the present invention is not limited to this. For example, the ECU 9 higher than the CPU 5 inputs the detected temperature signal from the temperature detection circuit 7b via the communication circuit 8, generates a self-shutoff signal and an overheat signal based on the detected temperature signal, and executes the control routine shown in FIG. This may be executed to transmit the new target rotational speed N (= 0 to N + n) to the CPU 5 via the communication circuit 8.
(5) In the above embodiment, for temperature protection of the motor drive device, the temperature Tph of the non-heat-generating component arranged at a position where heat resistance is the lowest and heat exchange with the suction refrigerant is difficult is detected. In response to the increase in Tph, the rotation speed of the electric motor 12 is increased when the temperature Tph is in the alarm state temperature range, and when the temperature Tph is further increased to the abnormal state temperature range, the non-heat-generating component is energized. Although it turned off, it is not restricted to this. That is, the temperature detection processing routine based on the temperature detection of the non-heat-generating component used in the above-described embodiment and the temperature protection based on the temperature Tph is used to detect the temperature Td of the heat-generating component known in the related art and to increase the temperature Td. A processing routine for increasing the number of rotations of the motor 12 may be added to perform the process twice.

It is a mimetic diagram of a vapor compression refrigeration machine using a motor drive unit integrated electric compressor concerning this embodiment. It is a figure which shows the arrangement | positioning condition in the engine room at the time of vehicle-mounted electric compressors. It is a schematic block diagram of a motor drive device. It is a schematic block diagram of a gate driver circuit. It is a flowchart showing the control routine of the temperature protection of a motor drive device. It is a figure which shows the relationship between the detection temperature of a non-heat-generating component, abnormality, an alarm, and each normal state. It is a figure which shows the temperature change of each part of an inverter immediately after the electric motor starting in a prior art. It is a figure which shows the temperature change of each part of an inverter during the electric motor stop in a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Electric compressor, 11 ... Compression mechanism, 12 ... Motor, 12a ... Motor housing,
13 ... Motor drive device (inverter), 2 ... switching circuit, 20 ... IGBT,
21 ... Circuit board, 22 ... Insulator support member, 3 ... Control circuit, 4 ... Internal power supply circuit,
5 ... CPU, 6 ... gate driver circuit, 7a ... photocoupler, 7b ... temperature detection circuit,
70: thermistor, 9 ... air conditioning control circuit (ECU).

Claims (7)

An electric compressor (10) comprising a compression mechanism (11) for sucking and compressing refrigerant, an electric motor (12) for driving the compression mechanism, and a motor drive device (13) for driving and controlling the electric motor,
The motor driving device is
An exothermic component (20) disposed so as to be able to exchange heat with the sucked refrigerant and generating heat in response to the operation of the electric motor;
Non-exothermic components (4, 5, 7a, 8, 61) other than the exothermic components;
Temperature detecting means (7b) for detecting the temperature of the non-heat-generating component;
A protection control unit (5, 9) for performing protection control of the motor drive device based on the detected temperature of the non-heat-generating component ,
The electric compressor characterized in that the protection control unit cuts off the energization to the non-heat-generating component when the detected temperature of the non-heat-generating component exceeds a preset predetermined temperature. . An electric compressor (10) comprising a compression mechanism (11) for sucking and compressing refrigerant, an electric motor (12) for driving the compression mechanism, and a motor drive device (13) for driving and controlling the electric motor,
The motor driving device is
An exothermic component (20) disposed so as to be able to exchange heat with the sucked refrigerant and generating heat in response to the operation of the electric motor;
Non-exothermic components (4, 5, 7a, 8, 61) other than the exothermic components;
Temperature detecting means (7b) for detecting the temperature of the non-heat-generating component;
A protection control unit (5, 9) for performing protection control of the motor drive device based on the detected temperature of the non-heat-generating component ,
The protection control unit drives the electric motor when the detected temperature of the non-heat-generating component exceeds a predetermined temperature when the electric motor is in a stopped state. Electric compressor. The temperature detection means detects the temperature of the exothermic component,
3. The electric compressor according to claim 2 , wherein the protection control unit increases the rotational speed of the electric motor by a predetermined amount when the temperature of the detected heat-generating component exceeds a predetermined temperature. . The electric compressor according to any one of claims 1 to 3, wherein the heat generating component is a power device (20) for driving the electric motor. The non-heat-generating component is at least one of a photocoupler (7a, 61), an internal power supply circuit (4), a CPU (5), a temperature detection circuit (7b), and a communication circuit (8). The electric compressor according to any one of claims 1 to 4 . Wherein the non-heat generating component is an electric compressor according to any one of claims 1 to 4, wherein the heat resistance of the parts constituting the motor drive device is the lowest part. The said protection control part increases the rotation speed of the said electric motor by a predetermined amount, when the temperature of the said non-heat-emitting component exceeds the predetermined temperature set beforehand. The electric compressor as described in any one of thru | or 6 .

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