JP5353025B2 - Control device for electric compressor - Google Patents

Description

  The present invention relates to an inverter device capable of diagnosing an electrical resistance on a DC power supply side before operation.

  The circuit and operation of an inverter device that has been conventionally performed will be described below. FIG. 10 shows an electrical circuit diagram of a conventional inverter device 120 and its periphery. Prior to operation, the magnet rotor 5 constituting the sensorless DC brushless motor 11 (hereinafter referred to as a motor) is positioned. The positioning is performed by outputting a direct current from the inverter device 120 to the stator winding 4 constituting the motor 11 (see, for example, Patent Document 1). FIG. 11A shows a case where the magnet rotor 5 is positioned with the U and V phases of the stator winding 4 as the S pole and the W phase as the N pole in the case of four poles. The N pole of the magnet rotor 5 is positioned on the S pole of the stator winding 4 and the S pole of the magnet rotor 5 is positioned on the N pole of the stator winding 4 so as to be opposed to each other. . At this time, the control circuit 107 of the inverter device 120 controls the switching element 2 so that current flows from the W phase to the U phase and the V phase of the stator winding 4 as shown in FIG. Further, the control circuit 107 detects the phase current of the motor with the current sensor 106.

During operation, the control circuit 107 controls the switching element 2 (IGBT, FET, transistor, etc.) constituting the inverter circuit, so that the DC voltage from the battery 1 is switched by PWM modulation and is sinusoidal. Is output to the stator winding 4 constituting the motor 11. Thereby, the motor 11 is driven. The diode 3 serves as a circulation route for the current flowing through the stator winding 4. The detected current value of the current sensor 106 is sent to the control circuit 107, used for power consumption calculation, switching element 2 protection, and the like, and further used for position estimation of the magnet rotor 5.
Japanese Patent Laid-Open No. 11-356088 (page 7, FIG. 6)

  As described above, in the conventional inverter device, the operation is started immediately after the positioning of the magnet rotor. For this reason, when the internal resistance of the DC power supply is large, or when the wiring resistance on the DC power supply side is large, the power loss is increased by the resistance when the motor in which a large current flows is started. Therefore, it is desirable to diagnose the electrical resistance on the DC power supply side before operation and take appropriate measures. In addition, when operating, it is desirable to take measures so that power loss does not increase.

  The present invention solves such a conventional problem, and it is possible to diagnose an electrical resistance on the side of a DC power source before operation, and further, an inverter device that prevents an increase in power loss when the electrical resistance is large. For the purpose of provision.

In order to solve the above-described problems, an electric compressor control device according to the present invention includes an electric compressor including a compression mechanism unit that compresses refrigerant, a motor that drives the compression mechanism unit, and an inverter device that controls the motor. The inverter device comprises an inverter circuit having an upper arm switching element connected to the positive side of the DC power source and a lower arm switching element connected to the negative side, and a voltage detection for detecting a DC voltage from the DC power source And a control circuit that outputs a DC current from the inverter circuit to the motor before operation to position the magnet rotor of the motor and outputs an AC current from the inverter circuit to the motor during operation. , when the magnet rotor positioning, the positioning current detected by predetermined positioning current or shunt resistor value and the voltage Out device by calculating the electrical resistance of the DC power source side based on the DC voltage value detected, when the electric resistance of the DC power supply side is diagnosed with greater than a predetermined threshold value, the motor operation start Slowly start the motor while suppressing the current.

  On the DC power supply side, there are electrical resistances such as internal resistance and wiring resistance of the DC power supply. For this reason, a voltage will fall if an electric current flows. The direct current power supply has an increased internal resistance due to a decrease in performance. In addition, the wiring resistance increases due to a wiring defect or the like. As a result, the voltage drop due to current flow increases. When positioning the magnet rotor, a direct current is passed. Therefore, the magnitude of the electric resistance on the DC power supply side can be diagnosed by examining the magnitude of the voltage drop when positioning the magnet rotor. The electrical resistance diagnosis on the DC power supply side before the operation can be realized without preparing an inspection device. Moreover, since only the magnetic rotor positioning software that is always performed before the start-up operation is applied, the addition of the function has a small burden in terms of software.

  The inverter device according to the present invention can make an electrical resistance diagnosis on the DC power supply side before operation, and can further prevent an increase in power loss when the electrical resistance is large.

  According to a first aspect of the present invention, there is provided an inverter device including an inverter circuit including an upper arm switching element connected to a plus side of a DC power source and a lower arm switching element connected to a minus side, and detecting a DC voltage from the DC power source. It is equipped with a voltage detector and a control circuit that outputs a direct current from the inverter circuit to the motor before operation to position the magnet rotor of the motor and outputs an alternating current from the inverter circuit to the motor during operation. The circuit diagnoses the electric resistance on the DC power source side based on the DC voltage value detected by the voltage detector when positioning the magnet rotor.

  Thereby, the magnitude of the electrical resistance on the DC power supply side can be diagnosed before operation. The electrical resistance diagnosis on the DC power supply side before the operation can be realized without preparing an inspection device.

  According to a second aspect of the present invention, in the inverter device according to the first aspect of the present invention, the diagnosis of electrical resistance on the DC power supply side is performed in consideration of the temperature on the DC power supply side. When the temperature is low, the internal resistance of the DC power supply is large. Therefore, the electrical resistance diagnosis on the DC power supply side can be accurately performed by considering the temperature.

  According to a third invention, in the inverter device of the second invention, the temperature on the DC power supply side is calculated based on the resistance value obtained by calculating the resistance value of the stator winding of the motor when the magnet rotor is positioned. The temperature is used as a substitute. Therefore, it is not necessary to install a special temperature sensor or the like.

  According to a fourth aspect of the present invention, in the inverter device according to the first to third aspects, when it is diagnosed that the electric resistance is large, the rise at the start of operation is made gentle. Thereby, even at the time of starting the motor in which a large current flows, it is possible to suppress power loss due to the electric resistance on the DC power supply side.

  According to a fifth aspect of the present invention, in the inverter device according to the first to fourth aspects, when the electrical resistance is diagnosed, the maximum output during operation is limited. Thereby, it can prevent that a big electric current flows and can suppress the power loss by the electrical resistance by the side of a DC power supply.

  A sixth invention drives the motor of the electric compressor in the inverter device of the first to fifth inventions. In an electric compressor, since the current at the start of air conditioning is large and the current at steady state is also large, this inverter device that diagnoses the electrical resistance on the DC power source side and prevents an increase in power loss when the electrical resistance is large is useful. is there.

  A seventh invention is an inverter device according to the first to sixth inventions, which is mounted on a vehicle. The DC power supply and wiring mounted on the vehicle are severe in environment such as vibration. Therefore, this inverter device that diagnoses the electrical resistance on the DC power supply side and prevents an increase in power loss when the electrical resistance is large is useful.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiment.

(Embodiment 1)
FIG. 1 shows an inverter device 20 according to Embodiment 1 of the present invention and an electric circuit around it. The positioning energization of the magnet rotor 5 before operation will be described below. FIG. 2A shows a case where the magnet rotor 5 is positioned with the U phase and V phase of the stator winding 4 set to the S pole and the W phase set to the N pole in the case of four poles. The N pole of the magnet rotor 5 is positioned on the S pole of the stator winding 4 and the S pole of the magnet rotor 5 is positioned on the N pole of the stator winding 4 so as to be opposed to each other. . At this time, the control circuit 7 of the inverter device 20 controls the switching element 2 so that current flows from the W phase to the U phase and the V phase of the stator winding 4 as shown in FIG. The control circuit 7 detects the phase current of the motor based on the voltage from the shunt resistor 6.

  FIG. 3 shows an example of the ON period within the carrier cycle of the upper arm switching element in positioning in relation to the above switching. The thin line is the U phase, the middle line is the V phase, and the thick line is the W phase. The energization period is set so that a predetermined constant current flows. As an example, the DC voltage of the battery 1 is set to DC 300 V, the resistance value R of each phase of the stator winding 4 shown in FIG. 4 is set to 1Ω, and the carrier frequency is 10 kHz (carrier cycle is 100 μS). Here, in order to set the phase current value of the W phase in positioning to 20 A, the equivalent resistance value of the stator winding 4 is 1.5Ω, and therefore it is necessary to apply a DC equivalent of 30 V. DC30V is 10% of DC300V. Therefore, the total of the first half and the second half displayed as Duty of the energization period, that is, Δt may be set to 10% (10 μS). Approximately 100 mS (carrier cycle 1000 times) is executed. FIG. 5 shows the time course of the W-phase phase current. As the current rises and the predetermined constant DC current flows, the magnet rotor 5 is positioned.

  The operation will be described below. The control circuit 7 calculates the induced voltage of the stator winding 4 by the magnet rotor 5 constituting the motor 11 and estimates the position of the magnet rotor 5. Then, based on the position estimation, the rotation speed command signal (not shown), etc., the switching element 2 constituting the inverter circuit 10 is controlled, and the DC voltage from the battery 1 is switched by PWM modulation. An alternating current is output to the stator winding 4 of the motor 11. The control circuit 7 is connected to the upper arm switching elements U, V, W and the lower arm switching elements X, Y, Z by a connection line 18 via a drive circuit or the like, and controls each switching element. When the switching element 2 is an IGBT or a power MOSFET, the gate voltage is controlled. When the switching element 2 is a power transistor, the base current is controlled. The diodes 3 corresponding to the switching elements U, V, W, X, Y, and Z are defined as 3U, 3V, 3W, 3X, 3Y, and 3Z.

  Next, the electrical resistance diagnosis on the DC power source side during positioning will be described below. FIG. 6 is a flowchart showing an example of the operation of the inverter device 20. In step 10, the above-described positioning is performed. At this time, a positioning current (20 A in the above embodiment) flows through the DC power supply line of the battery 1 in the first half and the latter half of the period indicated by Δt in FIG. This current is detected by the voltage from the shunt resistor 6. Further, since this current flows through the electric resistance 25 on the battery 1 (DC power supply) side, the DC voltage from the battery 1 decreases. This voltage drop is detected by the battery voltage detector 8. The voltage detector 8 can be easily configured by dividing the battery voltage by a resistor. Further, a battery voltage detector provided to accurately output the voltage even when the DC voltage of the battery 1 fluctuates may be used.

  In step 20, the electric resistance 25 is calculated from this voltage drop. If the positioning current is 20 A and the voltage drop is 20 V, 1Ω is obtained. As the positioning current, a value detected by the shunt resistor 6 may be used. Here, if the determination of pass / fail of the electrical resistance is 1Ω, if it is 0.5Ω (Y), the process proceeds to step 60 and the normal operation is performed. If the electrical resistance is 1.5Ω (N), the process proceeds to step 30, and information that the electrical resistance is large is transmitted to a controller (not shown). As a result, the user or the like can be recognized. Then, the process proceeds to step 40, where the rise at the start of operation is moderated. Thereby, even when the motor 11 in which a large current flows is started, power loss due to the electric resistance on the battery 1 side can be suppressed. Moreover, it moves to step 50 and limits the maximum output during operation. Thereby, it can prevent that a big electric current flows and can suppress the power loss by the electrical resistance of the battery 1 side. Only one of step 40 and step 50 may be used.

  As a result, it is possible to diagnose the electric resistance on the battery 1 side before operation without preparing an inspection device, and it is possible to prevent an increase in power loss when the electric resistance is large. And since only the positioning software of the magnet rotor 5 that is always performed before the start-up operation is applied, the addition of the function has a small burden in terms of software. Here, the electrical resistance quality determination 1Ω in step 20 may be changed in consideration of the temperature of the battery 1. Since the internal resistance of the battery 1 increases when the temperature is low, the electrical resistance diagnosis of the battery 1 can be accurately performed by changing to 1.5Ω or the like when the temperature is low. This temperature may be received from a controller (not shown) or the like. Further, this temperature may be substituted with the temperature calculated based on the resistance value of the stator winding 4 of the motor 11 calculated when the magnet rotor 5 is positioned. This is because the resistance value of the stator winding 4 and the temperature of the stator winding 4 are in a linear relationship. According to this, it is not necessary to install a special temperature sensor or the like.

  In the above embodiment, the case where the U-phase and V-phase of the stator winding 4 are set to the S-pole and the W-phase is set to the N-pole is shown, and the 4-pole magnet rotor 5 is positioned. The phase of the S pole and the N pole of the stator winding 4 is arbitrary, and is applicable to two poles, six poles, etc., and also when a current is passed through only two phases of the stator winding 4. it can. The shunt resistor 6 may be provided on the plus side of the power supply line. Further, it may be provided on the negative side of the lower arm switching element and the power supply line. The current sensor is not limited to a shunt resistor, and may be any sensor that can detect an instantaneous peak current, such as a current sensor using a Hall element. It may be provided between the inverter circuit 10 and the motor 11 to directly detect the motor current (phase current). The period of the startup operation is not limited to the example in FIG. Although the W-phase current is shown, the U-phase and the V-phase behave in the same way only with different phases.

(Embodiment 2)
FIG. 7 is an electric circuit diagram of the inverter device 21 according to the second embodiment of the present invention and its periphery. Compared to FIG. 1 in the first embodiment, a smoothing capacitor 24 and an electric resistor 26 on the smoothing capacitor side are added, and the control circuit 7 is changed to the control circuit 9. In this case, the parallel circuit of the battery 1 and the smoothing capacitor 24 is regarded as one DC power source and may be handled in the same manner as in the first embodiment. The same applies even if the smoothing capacitor 24 is installed not on the inverter device 21 but on the battery 1 side.

(Embodiment 3)
FIG. 8 is a diagram in which the inverter device 20 is attached in close contact with the right side of the electric compressor 40. The compression mechanism 28, the motor 11, and the like are installed in the metal casing 32. The refrigerant is sucked from the suction port 33 and compressed by the compression mechanism 28 (scroll in this example) being driven by the motor 11. The compressed refrigerant cools the motor 11 when passing through the motor 11 and is discharged from the discharge port 34.

  The inverter device 20 uses a case 30 so as to be attached to the electric compressor 40. The inverter circuit unit 10 serving as a heat source is cooled by the low-pressure refrigerant through the low-pressure pipe 38. A terminal 39 connected to the stator winding 4 of the motor 11 inside the electric compressor 40 is connected to the output section of the inverter circuit section 10. The connection line 36 fixed to the inverter device 22 by the holding unit 35 includes a power line to the battery 1 and a signal line to an air conditioner controller (not shown) that transmits a rotation speed signal.

  In an electric compressor, since the current at the start of air conditioning is large and the current at steady state is also large, this inverter device that diagnoses the electrical resistance on the battery 1 side and prevents an increase in power loss when the electrical resistance is large is useful. is there. Further, since the vibration is received from the compression mechanism 28, the present inverter device that can diagnose the electric resistance on the battery 1 side is useful.

  In the above embodiment, the compression mechanism of the electric compressor is a scroll. However, the present invention is not limited to this. Moreover, although the compressed refrigerant showed about the high voltage | pressure type which cools a motor, a low voltage | pressure type may be sufficient. The temperature of the inverter device 20 may be substituted for the temperature of the battery 1 in the embodiment.

(Embodiment 4)
FIG. 9 shows an example in which the inverter device of the present invention is configured integrally with a compressor (Embodiment 3) and applied to an air conditioner and mounted on a vehicle 60. The inverter device-integrated electric compressor 61, the outdoor heat exchanger 63, and the outdoor fan 62 are mounted in an engine room (or motor room) in front of the vehicle 60. On the other hand, an indoor fan 65, an indoor heat exchanger 67, and an air conditioner controller 64 are disposed in the vehicle compartment. Air outside the vehicle is sucked from the air introduction port 66, and the air heat-exchanged by the indoor heat exchanger 67 is blown into the vehicle interior.

  The battery 1 and wiring mounted on the vehicle are severe in environment such as vibration. Therefore, the present inverter device that diagnoses the electrical resistance on the battery 1 side and prevents an increase in power loss when the electrical resistance is large is useful.

  In each of the above embodiments, the DC power source is a battery. However, the present invention is not limited to this, and a DC power source rectified from a commercial AC power source may be used. Although the motor is a sensorless DC brushless motor, it can be applied to a motor that requires positioning, such as a reluctance motor. The present invention is not limited to sinusoidal driving, and can be applied to a driving method that requires detection of a phase current during positioning. It can also be applied to PWM two-phase modulation.

  As described above, the inverter device according to the present invention can make an electrical resistance diagnosis on the DC power supply side before operation, and can further prevent an increase in power loss when the electrical resistance is large. Therefore, it can be applied to various consumer products and various industrial equipment.

The inverter apparatus which concerns on Embodiment 1 of this invention, and its surrounding electric circuit diagram (A) Positional relationship diagram of stator winding and magnet rotor during positioning, (B) Current explanation diagram of stator winding during positioning Explanatory drawing showing an example of energization during the same positioning Explanatory drawing showing impedance of the same stator winding Illustration of phase current of W phase from the same positioning to operation Flow chart showing an operation example of the inverter device The inverter apparatus which concerns on Embodiment 2 of this invention, and its surrounding electric circuit diagram Sectional drawing of the inverter apparatus integrated electric compressor which concerns on Embodiment 3 of this invention. Schematic diagram of a vehicle equipped with an inverter device according to Embodiment 4 of the present invention Conventional inverter device and peripheral electrical circuit diagram (A) Positional relationship diagram of stator winding and magnet rotor during positioning, (B) Current diagram of stator winding during positioning

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery 2 Switching element 4 Stator winding 5 Magnet rotor 7 Control circuit (inverter apparatus 20)
9 Control circuit (inverter device 21)
DESCRIPTION OF SYMBOLS 8 Battery voltage detector 10 Inverter circuit 11 Sensorless DC brushless motor 20 Inverter apparatus 21 Inverter apparatus 24 Smoothing capacitor 25 Electric resistance on the DC power supply side 26 Electric resistance on the smoothing capacitor side 40 Electric compressor 60 Vehicle

Claims (5)

An electric compressor including a compression mechanism unit that compresses the refrigerant and a motor that drives the compression mechanism unit, and an inverter device that controls the motor, and the inverter device is connected to the positive side of a DC power source. An inverter circuit having an arm switching element and a lower arm switching element connected to the negative side, a voltage detector for detecting a DC voltage from the DC power supply, and outputting a DC current from the inverter circuit to the motor before operation A control circuit for positioning the magnet rotor of the motor and outputting an alternating current from the inverter circuit to the motor during operation, and the control circuit is predetermined when positioning the magnet rotor. value and the detection of the voltage detector was positioned current or positioning current detected by the shunt resistor That based on the DC voltage value to calculate the electric resistance of the DC power supply side, when said electrical resistance of the DC power supply side is diagnosed with greater than a predetermined threshold value, during operation starting of the motor The control apparatus of the electric compressor which suppresses the electric current and starts the motor gently. The electrical resistance diagnosis on the DC power supply side is performed by making the threshold value large as the temperature on the DC power supply side decreases and decreasing as the temperature on the DC power supply side increases. Control device for electric compressor. The temperature on the DC power supply side is substituted by a temperature calculated based on the resistance value calculated from the resistance value of the stator winding of the motor when the magnet rotor is positioned. Control device for electric compressor. 4. In the electrical resistance diagnosis on the DC power supply side, when the electrical resistance is diagnosed to be greater than a predetermined threshold value , the maximum output during operation is limited. The control apparatus of the electric compressor of description. The control apparatus of the electric compressor as described in any one of Claims 1-4 mounted in a vehicle.

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