JP5256837B2 - Inverter device - Google Patents

Description

  The present invention relates to an inverter device for diagnosing the state of electrical connection between an inverter circuit and a motor based on a positioning current value of a magnet rotor before the operation of the motor.

  Conventionally, there has been proposed an inverter device that diagnoses whether or not electrical connection is made, that is, whether or not there is electrical connection (see, for example, Patent Document 1). This will be described below. FIG. 10 is an example of a conventional automobile air conditioner diagram. A capacitor 103 is provided between the battery 101 as a DC power source and the electric compressor driving device 104 (inverter circuit) in order to smooth the current. An electric compressor 105 is connected to the electric compressor driving device 104 by a connector 119, the battery 101 and the electric compressor driving device 104 are connected by a connector 111, and a fuse 106 for circuit protection is provided at an intermediate portion. . A charging resistor 109 for charging the capacitor 103, a relay 108 for supplying electric power from the battery 1 to the electric compressor driving device 4, a relay 108, and a control circuit 110 for operating the electric compressor driving device 104 are also provided. The diode 112 is provided so that the capacitor 103 is not charged and the circuit is not damaged even when the battery 101 which is a DC power supply is connected in reverse polarity. A charging current detection circuit 114 is connected in parallel with the charging resistor 109, and an output of the charging current detection circuit 114 is connected to the control circuit 110.

  Here, it is assumed that both the connector 111 and the connector 119 are normally connected. The control circuit 110 operates the electric compressor driving device 104 while keeping the relay 108 open. At this time, current flows from the battery 101 to the fuse 106, the connector 111, the diode 112, the charging resistor 109, the electric compressor driving device 104, the connector 119, and the electric compressor 105. Therefore, the current flows through the charging resistor 109 to generate a voltage. At this voltage, the LED of the charging current detection circuit 114 is turned on, the phototransistor is turned on, and the voltage of the control circuit power supply 107 is transmitted to the control circuit 110. For this reason, the control circuit 110 determines that both the connector 111 and the connector 119 are normally connected.

Here, it is assumed that the connector 119 is not connected. The control circuit 110 operates the electric compressor driving device 104 while keeping the relay 108 open. At this time, no current flows to the electric compressor driving device 104, the connector 119, and the electric compressor 105. Therefore, no current flows through the charging resistor 109 and no voltage is generated. The LED of the charging current detection circuit 114 is not lit, so that the phototransistor remains OFF, and the voltage of the control circuit power supply 107 is not transmitted to the control circuit 110. Therefore, the control circuit 110 determines that either the connector 111 or the connector 119 is not connected.
JP-A-10-193960 (page 4, FIG. 1)

  As described above, in the conventional inverter device, it is possible to diagnose whether or not electrical connection is made, that is, the presence or absence of electrical connection. However, it is impossible to diagnose the state of electrical connection such as connection failure or contact failure of the connector 119 or the like. If there is a connection failure or contact failure, it can cause failure, so it is desirable to be able to detect it early. In the case of poor connection or poor contact, the resistance value is larger than that in the normal case, but the value is small, several Ω. Therefore, a small current has a small potential difference and is difficult to diagnose. Moreover, it is difficult to calculate a resistance value with an alternating current. If a dedicated diagnostic circuit is added to the inverter device, the size will increase. Moreover, when not diagnosing with an inverter apparatus, it is necessary to prepare a test | inspection apparatus etc. and work is also required.

  The present invention solves such a conventional problem, and it is not necessary to add a special diagnostic circuit, and it is possible to diagnose the state of electrical connection such as connection failure and contact failure without preparing an inspection device or the like. An object of the present invention is to provide an inverter device capable of

  In order to solve the above problems, an inverter device according to the present invention includes an inverter circuit including an upper arm switching element connected to the plus side of a DC power source and a lower arm switching element connected to the minus side, and an inverter circuit. A motor circuit that outputs a motor current to a sensorless DC brushless motor by energizing PWM modulation and a current sensor that detects the motor current, and outputs a DC current from the inverter circuit to the motor before the motor is operated. When the positioning is performed, the control circuit diagnoses the state of the electrical connection between the inverter circuit and the motor based on the direct current value detected by the current sensor with the PWM modulation fixed.

  Thereby, since the current value for positioning is large and direct current, a small resistance value necessary for diagnosing the state of electrical connection can be easily calculated. Therefore, it is not necessary to add a special diagnostic circuit, and the state of electrical connection can be diagnosed without preparing an inspection device or the like. In addition, if a diagnosis is made at each start-up, a connection failure, a contact failure, etc. can be detected early. You can make a practical application simply by modifying and adding control software for positioning.

  The inverter device of the present invention does not require any special diagnostic circuit, and can diagnose the state of electrical connection such as connection failure and contact failure without preparing an inspection device or the like.

  According to a first aspect of the present invention, there is provided an inverter circuit having an upper arm switching element connected to the plus side of a DC power source and a lower arm switching element connected to the minus side, and sensorless motor current by applying PWM modulation to the inverter circuit. In an inverter device that includes a control circuit that outputs to a DC brushless motor and a current sensor that detects motor current, outputs a DC current from the inverter circuit to the motor before the motor is operated, and positions the magnet rotor of the motor. When positioning the rotor, the control circuit diagnoses the state of the electrical connection between the inverter circuit and the motor based on the direct current value detected by the current sensor with the PWM modulation fixed.

  Thereby, since the current value for positioning is large and direct current, a small resistance value necessary for diagnosing the state of electrical connection can be easily calculated. Therefore, the state of electrical connection can be diagnosed without adding a special diagnostic circuit or preparing an inspection device. In addition, if a diagnosis is made at each start-up, a connection failure, a contact failure, etc. can be detected early.

  According to a second aspect of the invention, in the inverter device of the first aspect of the invention, the state of electrical connection is diagnosed by taking into account the direct-current voltage value of the direct-current power supply. Thereby, even if the DC voltage value of the DC power supply is changed, the state of electrical connection can be accurately diagnosed by adjusting the PWM modulation or changing the current reference value for determination.

According to a third invention, in the inverter device of the first or second invention, the state of the electrical connection is diagnosed in consideration of the temperature of the motor. Thus, even if the resistance value of the stator winding is changed, the state of electrical connection can be accurately diagnosed by adjusting the PWM modulation or changing the determination current reference value.

  A fourth invention drives the motor of the electric compressor in the inverter devices of the first to third inventions. The motor of the electric compressor is accommodated in the container. Therefore, it is necessary to use an inspection device to confirm the state of electrical connection around the motor. Therefore, this inverter device that can diagnose the state of electrical connection by the inverter device itself is useful.

  According to a fifth invention, in the inverter device of the fourth invention, the electric compressor is a high pressure type. In a high-pressure type electric compressor, the motor becomes hot, that is, the stator winding becomes hot. Therefore, when the temperature of the stator winding is high at the time of restart or the like, the present inverter device that can diagnose the state of electrical connection in consideration of the temperature is useful.

  According to a sixth invention, in the inverter device of the fourth or fifth invention, the inverter device is mounted on an electric compressor. In this case, the electrical connection from the inverter device to the electric compressor is also accommodated in the container. Therefore, it is necessary to use an inspection apparatus in the same manner. Therefore, this inverter device that can diagnose the state of electrical connection by the inverter device itself is useful.

  A seventh invention is an inverter device according to the first to sixth inventions, which is mounted on a vehicle. For vehicles, there are restrictions on the mounting space, and it is often mounted in a place where various devices and parts are involved. Therefore, inspection / confirmation becomes difficult. Therefore, the present inverter device that can diagnose the state of electrical connection by the device itself 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 22 according to Embodiment 1 of the present invention and an electric circuit around it. The control circuit 7 of the inverter device 22 detects the phase current of each phase of the motor current based on the voltage from the shunt resistor 6. If phase currents for two phases are detected, the phase currents for the remaining phases can be calculated from the two current values (Kirchhoff's current law is applied at the neutral point of the stator winding 4).

  During operation, the control circuit 7 calculates the induced voltage of the stator winding 4 by the magnet rotor 5 constituting the motor 11 based on the current values for these three phases, and detects the position of the magnet rotor 5. Do. Then, based on this position detection, 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 diode 3 constituting the inverter circuit 10 serves as a circulation route for the current flowing through the stator winding 4. For the switching element 2, upper arm switching elements are defined as U, V, W, and lower arm switching elements are defined as X, Y, Z, and diodes corresponding to the switching elements U, V, W, X, Y, Z Is defined as 3U, 3V, 3W, 3X, 3Y, 3Z. 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 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, as shown in FIG. 2B, the control circuit 7 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.

  FIG. 3 shows an example of the ON period within the carrier cycle of the upper arm switching element at the initial stage of 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. FIG. 3A shows a case where the energization period is set small in order to gradually increase the current in the initial stage of positioning. In the initial stage of positioning, the energization period is gradually increased as shown in FIGS. 3 (B) and 3 (C). Here, the time until the current has risen (initial positioning) is 50 mS. FIG. 4 shows the impedance of the stator winding 4. An inductance L exists along with a resistor R. Therefore, the current is gradually increased.

  In FIG. 5, the energization period is set so that a predetermined constant current flows in the stationary positioning period. Approximately 100 ms is executed. As an example, the DC voltage of the battery 1 is DC 300 V, the resistance value R of each phase of the stator winding 4 is 1Ω, and the carrier frequency is 10 kHz (carrier cycle 100 μS). Here, in order to set the phase current value of the W phase in the stationary positioning period to 20 A, since the equivalent resistance value of the stator winding 4 is 1.5Ω, it is necessary to apply a DC equivalent to 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).

  At this time, PWM modulation is fixed and phase current feedback control is not performed. The current detection by the shunt resistor 6 can be detected during a period in which the W-phase current is indicated as Δt. Although detailed explanation is omitted, it is impossible to detect a period in which all three phases are ON and a period in which both three phases are OFF. When only one phase is ON, the current of the phase can be detected. When only two phases are ON, the current of the remaining phase can be detected.

  Since the PWM modulation is fixed and the phase current feedback control is not performed, there is a connection failure, a contact failure, or the like between the inverter circuit 10 and the motor 11, and if there is a resistance value, the phase current value 20A becomes small. Assuming that the resistance value is 0.5Ω, the load is 2.0Ω from the equivalent resistance value 1.5Ω + 0.5Ω of the stator winding 4 with respect to DC30V, and therefore 15A. From this current value, a resistance value of 0.5Ω can be calculated. The connection state can be diagnosed using 20A as a reference value. Therefore, the state of the electrical connection between the inverter circuit 10 and the motor 11 can be diagnosed based on the phase current value (DC current value) detected by the shunt resistor 6 with the PWM modulation fixed.

  Thereby, since the current value for positioning is large and direct current, a small resistance value necessary for diagnosing the state of electrical connection can be easily calculated. Therefore, the state of electrical connection can be diagnosed without adding a special diagnostic circuit or preparing an inspection device. In addition, if a diagnosis is made at each start-up, a connection failure, a contact failure, etc. can be detected early.

  FIG. 6 shows the W-phase current from positioning to operation. The DC current during positioning shifts to a sinusoidal AC current during operation. In the stationary positioning period, the period in which the PWM modulation is fixed and the period in which the current is detected by the shunt resistor 6 is not limited to the whole period, but may be a part of the period in which current detection is possible. The latter half of the current stabilization is desirable. Moreover, if this diagnostic result is transmitted to a controller etc. which command a rotation speed command signal (not shown) by communication, a user can recognize a diagnostic result via the said controller.

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 to position the 4-pole magnet rotor 5, 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).

(Embodiment 2)
FIG. 7 shows an inverter device 23 according to the second embodiment of the present invention and its surrounding electric circuit. Compared to FIG. 1, a battery voltage detector 8 is added. In the numerical example, when the DC voltage DC300V of the battery 1 changes to 330V (10% increase), when there is no connection failure or contact failure, the current is 22A. Therefore, it is necessary to change the determination criterion to 22A. Alternatively, the reference value may be kept at 20 A, and the duty 10% (10 μS) of the energization period may be reduced by 10% to obtain a Duty 9% (9 μS). By providing a battery voltage detector 8, this is possible. The voltage information of the battery 1 may be obtained by communication from the controller without detecting the voltage of the battery 1 without providing the battery voltage detector 8.

  Thereby, even if the DC voltage value of the battery 1 changes, the state of electrical connection can be accurately diagnosed by adjusting the PWM modulation or changing the determination current reference value.

(Embodiment 3)
Since the PWM modulation is fixed and the phase current feedback control is not performed, when the temperature of the motor 11 is high, the resistance value of the stator winding 4 increases and the phase current value 20A decreases. In the above example, when the equivalent resistance value of the stator winding 4 is 1.5Ω to 2.0Ω, the phase current value is 15A. Accordingly, at this temperature, 15A may be set as a reference value. Alternatively, the reference value may be kept at 20 A, and Duty 10% (10 μS) of the energization period may be increased 33% to Duty 13.3% (13.3 μS).

  In FIG. 7, a motor temperature detector 9 for detecting the temperature of the motor 11 is installed in the vicinity of the stator winding 4. Based on the temperature detected by the motor temperature detector 9, as described above, the state of electrical connection can be accurately diagnosed by changing the current reference value or changing the current reference value without changing the current reference value. Can do. The temperature detector is not limited to the above, and an ambient temperature detector or the like may be substituted.

(Embodiment 4)
FIG. 8 shows a diagram in which the inverter device 22 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. That is, it is a high pressure type.

  The inverter device 22 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.

  The motor 11 of the electric compressor 40 is accommodated in a metal casing 32. Therefore, it is necessary to use an inspection device to confirm the state of electrical connection around the motor 11. Therefore, this inverter device that can diagnose the state of electrical connection by the inverter device 22 itself is useful. The inverter device 22 is mounted on the electric compressor 40. In this case, the terminal 39 and the like, which are electrical connections from the inverter device 22 to the electric compressor 40, are also accommodated in the case 30 and the like. Therefore, it is necessary to use an inspection apparatus in the same manner. Therefore, this inverter device that can diagnose the state of electrical connection by the inverter device 22 itself is very suitable. Further, since the electric compressor 40 is a high-pressure type, the motor 11 becomes high temperature, that is, the stator winding 4 becomes high temperature. Therefore, when the temperature of the stator winding 4 is high at the time of restart or the like, the resistance value of the stator winding 4 is large. Even in such a case, since the inverter device 22 diagnoses the state of electrical connection in consideration of the temperature, an accurate diagnosis can be performed.

  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.

(Embodiment 5)
FIG. 9 shows an example in which the inverter device of the present invention is configured integrally with a compressor (Embodiment 4) 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 inlet 66 and the air heat-exchanged by the indoor heat exchanger 67 is blown out into the vehicle interior.

  For vehicles, there is a limitation in the mounting space, and it is often mounted in a place where various devices and parts such as a motor room (or engine room) are complicated. Therefore, inspection / confirmation becomes difficult. Therefore, the present inverter device that can diagnose the state of electrical connection by the device itself is useful. In particular, in a hybrid car, since both the motor and the engine are mounted, the area around the electric compressor is complicated, and inspection and confirmation are not easy, and this inverter device is very suitable.

  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, since the inverter device according to the present invention can diagnose the state of electrical connection such as a connection failure without preparing an inspection device or the like, 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 explanatory diagram of stator winding during positioning (A) 1st explanatory drawing which shows the example of electricity supply in the initial stage of positioning (B) 2nd explanatory drawing (C) 3rd explanatory drawing Explanatory diagram showing impedance of stator winding Explanatory drawing showing an example of energization in the stationary positioning period Illustration of phase current of W phase from the same positioning to operation Inverter device according to Embodiment 2 and Embodiment 3 of the present invention and its surrounding electric circuit diagram Sectional drawing of the inverter apparatus integrated electric compressor which concerns on Embodiment 4 of this invention. Schematic diagram of a vehicle equipped with an inverter device according to Embodiment 5 of the present invention Conventional inverter device for diagnosing the presence or absence of electrical connection and the surrounding electrical circuit diagram

Explanation of symbols

1 Battery 2 Switching Element 3 Diode 4 Stator Winding 5 Magnet Rotor 6 Shunt Resistance (Current Sensor)
7 Control Circuit 8 Battery Voltage Detector 9 Motor Temperature Detector 10 Inverter Circuit 11 Sensorless DC Brushless Motor 22 Inverter Device (Embodiment 1)
23 Inverter device (Embodiment 2)
40 electric compressor 60 vehicle

Claims (7)

An inverter circuit having an upper arm switching element connected to the plus side of the DC power source and a lower arm switching element connected to the minus side, and outputting motor current to the sensorless DC brushless motor by applying PWM modulation to the inverter circuit And an inverter device for positioning a magnet rotor of the motor by outputting a direct current from the inverter circuit to the motor before operation of the motor. When positioning the magnet rotor, the control circuit diagnoses the state of electrical connection between the inverter circuit and the motor based on a direct current value detected by the current sensor with the PWM modulation fixed . The inverter apparatus according to claim 1, wherein a state diagnosis of the electrical connection is performed in consideration of a DC voltage value of the DC power supply. The inverter device according to claim 1, wherein a state diagnosis of the electrical connection is performed in consideration of a temperature of the motor. The inverter apparatus as described in any one of Claims 1-3 which drives the motor of an electric compressor. The inverter device according to claim 4, wherein the electric compressor is a high-pressure type. The inverter apparatus of Claim 4 or Claim 5 mounted in the said electric compressor. The inverter apparatus as described in any one of Claims 1-6 mounted in a vehicle.