JP2009189214A - Drive system and method for determining abnormality in capacitor provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more properly determine abnormality of a capacitor provided to a drive system. <P>SOLUTION: When an overcurrent is generated in either of inverters, or an overvoltage is generated between terminals of the capacitor, a system main relay is turned off (S100). A charge accumulated in the capacitor is discharged to a motor at a constant current (S140 or S150). When a discharge continuation time T at the time is smaller than a threshold Tref based on a discharge calculation time Tcal calculated by the capacitance of the capacitor, the voltage between the terminals, and the constant current, the system determines that the capacitor is abnormal (S200, S220). Accordingly, the system can determine abnormality of the capacitor more properly. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a drive device and a method for determining abnormality of a capacitor included in the drive device. More specifically, the motor, an inverter circuit that drives the motor, a DC power source that supplies power to the inverter circuit, a DC power source, and the inverter circuit are disconnected. The present invention relates to a drive device including a power supply circuit having a shut-off means for performing the operation and a capacitor connected between output terminals of the power supply circuit, and an abnormality determination method for determining an abnormality of the capacitor provided in the drive device.

Conventionally, this type of drive device is based on the voltage between terminals of a capacitor provided on the high voltage side of the boost converter in a device that boosts the voltage from the battery by the boost converter and supplies it to the inverter of the motor for driving. In order to discriminate between the abnormality of the inverter and the abnormality of the voltage sensor, for example, refer to Patent Document 1. In this device, when an abnormality is detected by the voltage across the terminals of the capacitor, the operation of the inverter and the boost converter is stopped, the battery is shut off, and the charge from the capacitor is applied to the resistor connected to the positive and negative buses of the inverter. Based on the time change of the voltage between the terminals of the capacitor when discharging, it is determined whether the inverter is abnormal or the voltage sensor is abnormal.
JP 2007-252134 A

  In the above-described driving device, it is possible to determine whether the inverter circuit is abnormal or the voltage sensor is abnormal, but it is not possible to determine this when the capacitor is abnormal. In addition, it is necessary to provide a resistor connected in parallel to the capacitor, and this resistor consumes some power even during normal operation, which is not preferable from the viewpoint of energy efficiency.

  The main purpose of the drive device and the capacitor abnormality determination method provided in the drive device of the present invention is to more appropriately determine the abnormality of the capacitor provided in the drive device.

  The drive device of the present invention and the capacitor abnormality determination method provided therein employ the following means in order to achieve the above-described main object.

The drive device of the present invention is
A power supply circuit having an electric motor, an inverter circuit for driving the electric motor, a DC power supply for supplying electric power to the inverter circuit, and a shut-off means for cutting off the connection between the DC power supply and the inverter circuit; and an output of the power supply circuit A drive device comprising a capacitor connected between the terminals,
Voltage detecting means for detecting a voltage between terminals of the capacitor;
When an abnormality occurs in the inverter circuit or when an overvoltage is detected by the voltage detection means, a predetermined current flows to the motor in a state where the connection between the DC power source and the inverter circuit is cut off by the interruption means. Capacitor abnormality determining means for determining abnormality of the capacitor based on a discharge duration time during which the predetermined current was able to flow when the inverter circuit was controlled;
It is a summary to provide.

  In the drive device of the present invention, when an abnormality occurs in the inverter circuit or an overvoltage occurs in the capacitor, the inverter circuit is controlled so that a predetermined current flows to the motor with the connection between the DC power source and the inverter circuit cut off. The abnormality of the capacitor is determined based on the discharge continuation time during which a predetermined current can be passed. Thereby, abnormality of a capacitor can be determined more appropriately. In addition, it is not necessary to provide a special circuit or element for determining the abnormality of the capacitor.

  In such a driving apparatus of the present invention, the capacitor abnormality determining means sets the voltage detected by the voltage detecting means when the predetermined current starts to flow to the electric motor to V, sets the capacitance of the capacitor to C, and sets the predetermined current. It is also possible to determine that the capacitor is abnormal when the discharge duration is less than the time based on T calculated by T = CV / I. Here, as the “time based on T”, the time of T itself or a time slightly shorter than T can be used.

  Furthermore, in the driving apparatus of the present invention, the capacitor abnormality determining means may be means for controlling the inverter circuit so that the predetermined current flows to the electric motor as a d-axis current. If it carries out like this, electric power can be consumed, without producing a torque in an electric motor.

  Furthermore, in the drive device according to the present invention, the electric motor is a plurality of electric motors, the inverter circuit is a plurality of inverter circuits for the plurality of electric motors, and the capacitor abnormality determining means is abnormal in any of the plurality of inverter circuits. An inverter circuit in which the abnormality does not occur so that the predetermined current flows to an electric motor corresponding to the inverter circuit in which the abnormality does not occur using an inverter circuit in which no abnormality has occurred among the plurality of inverter circuits. It can also be a means for controlling

  In addition, in the driving device of the present invention, the power supply circuit may be a circuit having a booster circuit that boosts the power of the DC power supply and supplies the boosted power to the inverter circuit.

The capacitor abnormality determination method of the present invention is:
A power supply circuit having an electric motor, an inverter circuit for driving the electric motor, a DC power supply for supplying electric power to the inverter circuit, and a shut-off means for cutting off the connection between the DC power supply and the inverter circuit; and an output of the power supply circuit An abnormality determination method for determining abnormality of the capacitor in a driving device including a capacitor connected between terminals,
When an abnormality occurs in the inverter circuit or when an overvoltage occurs in the capacitor, the inverter is configured such that a predetermined current flows through the motor in a state where the connection between the DC power source and the inverter circuit is interrupted by the interrupting means. Discharge calculated based on a voltage between terminals of the capacitor and a capacitance of the capacitor when the predetermined duration of current when the circuit was controlled was able to flow the predetermined current starts to flow to the electric motor Determining that the capacitor is abnormal when it is shorter than a time based on a calculation time;
It is characterized by that.

  In the capacitor abnormality determination method according to the present invention, when an abnormality occurs in the inverter circuit or when an overvoltage occurs in the capacitor, the inverter is configured such that a predetermined current flows to the motor with the connection between the DC power source and the inverter circuit cut off. The time based on the discharge calculation time calculated based on the voltage between the terminals of the capacitor and the capacity of the capacitor when the predetermined current begins to flow to the motor when the predetermined current can flow when the circuit is controlled When it is shorter, it is determined that the capacitor is abnormal. Thereby, abnormality of a capacitor can be determined more appropriately. In addition, it is not necessary to provide a special circuit or element for determining the abnormality of the capacitor.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of a configuration of a drive system 20 as an embodiment of the present invention. The drive system 20 according to the embodiment includes motors MG1 and MG2 capable of generating and outputting power, inverters 41 and 42 as drive circuits for the motors MG1 and MG2, and a battery 50 that exchanges power with the inverters 41 and 42. The system main relay 56 that disconnects the battery 50 from the inverters 41 and 42 and the electronic control unit 70 that controls the entire drive system 20 are provided.

  Both the motor MG1 and the motor MG2 are configured as well-known synchronous generator motors. The inverters 41 and 42 include six transistors T11 to T16 and T21 to 26, and six diodes D11 to D16 and D21 to D26 connected in parallel to the transistors T11 to T16 and T21 to T26 in the reverse direction. Yes. Two transistors T11 to T16 and T21 to T26 are arranged in pairs so that each of the inverters 41 and 42 serves as a source side and a sink side with respect to the positive electrode bus 54a and the negative electrode bus 54b shared by the power line 54. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motors MG1, MG2 is connected to each connection point between the paired transistors. Therefore, a rotating magnetic field is formed in the three-phase coil by controlling the ratio of the on-time of the transistors T11 to T16 and T21 to T26 that make a pair while a voltage is acting between the positive electrode bus 54a and the negative electrode bus 54b. The motors MG1, MG2 can be driven to rotate. A capacitor 57 for smoothing the voltage is attached between the positive electrode bus 54a and the negative electrode bus 54b.

  The electronic control unit 70 is configured as a microprocessor centered on the CPU 72, and includes a ROM 74 that stores a processing program, a RAM 76 that temporarily stores data, an input / output port, and a communication port in addition to the CPU 72. The electronic control unit 70 includes phase currents from current sensors 45U, 45V, 45W, 46U, 46V, and 46W that detect phase currents flowing in the respective phases of the three-phase coils of the motors MG1 and MG2, a positive bus 54a, and a negative bus 54b. The voltage V of the capacitor 57 from the voltage sensor 57a attached to the input terminal is input via the input port. The electronic control unit 70 outputs a drive signal to the system main relay 56 and switching control signals to the transistors T11 to T16 and T21 to T26 of the inverters 41 and 42 via the output port. The electronic control unit 70 executes an overcurrent detection routine (not shown), and applies a predetermined current to each of the inverters 41 and 42 based on the phase currents input from the current sensors 45U, 45V, 45W, 46U, 46V, and 46W. It detects that an overcurrent exceeding the allowable current flows, and outputs overcurrent errors Finv1 and Finv2, respectively. Further, the electronic control unit 70 executes an overvoltage detection routine (not shown) so that the voltage V of the capacitor 57 is set to an upper limit value of a voltage that can be applied without damaging the inverters 41 and 42 or a value slightly lower than the upper limit value. When an overvoltage state exceeding the allowable voltage Vhi (for example, 750 [V] when the normal drive voltage Vo that can normally drive the inverters 41 and 42 is 650 [V]) is detected, an overvoltage error OV is output.

  Next, the operation of the drive system 20 of the embodiment configured as described above, particularly when an abnormality occurs in which one of the inverters 41 and 42 has an overcurrent exceeding the allowable current, or the voltage between the terminals of the capacitor 57 is increased. An operation for determining abnormality of the capacitor 57 when an overvoltage is detected will be described. FIG. 2 is a flowchart showing an example of an abnormality determination routine executed by the electronic control unit 70. This routine is executed when one of the overcurrent errors Finv1 and Finv2 is output, or when the overvoltage error OV is output.

  When the abnormality determination routine is executed, the CPU 72 of the electronic control unit 70 first executes a process of turning off the system main relay 56 in order to cut off the supply of power from the battery 50 to the inverters 41 and 42 (steps). S100), processing for inputting data used for control such as the voltage V of the capacitor 57 from the voltage sensor 57a and overcurrent errors Finv1 and Finv2 is executed (step S110), and the capacitor 57 is turned on when the system main relay 56 is turned off. As shown in the following equation (1), a discharge calculation time Tcal, which is a calculated value of the discharge duration when the stored charge is discharged at a constant current I, is input to the normal capacity C of the capacitor 57 and the input voltage. Calculated by dividing the product of V by the constant current I, and used to determine abnormality of the capacitor 57 in the processing described later. Reduced set by a predetermined time α from the discharge calculation time Tcal to indicate threshold Tref as electrodeposition time following equation (2) (step S120). Here, the constant current I is determined in advance by the characteristics of the motors MG1 and MG2, the voltage of the battery 50, and the like as the current value when discharging the electric charge stored in the capacitor 57. Further, the threshold value Tref is set as a lower limit value of the discharge time during which the capacitor 57 can be determined to be normal, and when the capacitor 57 is normal when the capacity C of the capacitor 57 decreases and the original performance cannot be exhibited. Compared to the fact that the stored charge is reduced and the discharge time is shortened, this is used when determining an abnormality in the processing described later. Note that the value obtained by subtracting the predetermined time α from the discharge calculation time Tcal is set as the threshold Tref in consideration of the fact that the actual discharge time slightly decreases from the discharge calculation time Tcal due to loss during discharge, or the drive system 20 This is because it is determined to be normal until the capacitor capacity decreases to such an extent that does not hinder the operation. The predetermined time α can be set using an experimental value or the like.

Tcal = C ・ V / I (1)
Tref = Tcal-α (2)

  When the threshold value Tref is thus set, the outputs of the overcurrent errors Finv1 and Finv2 of the inverters 41 and 42 are checked (step S130). When the overcurrent error Finv1 is output, the constant current I is set as the d-axis current to the motor MG2. The inverter 42 is subjected to switching control so as to flow through the three-phase coil (step S140). On the other hand, when the overcurrent error Finv2 is output in step S130, or when no overcurrent error is output, the inverter 41 is configured so that the constant current I flows through the three-phase coil of the motor MG1 as the d-axis current. Is controlled to be switched (step S150). That is, in the processing of steps S130 to S150, the electric charge stored in the capacitor 57 is discharged by passing the constant current I as the d-axis current through the three-phase coil of the motor MG1 or MG2 on the inverter side where no overcurrent error has occurred. It becomes processing. Here, the d-axis current is caused to flow through the three-phase coil of the motor MG1 or the motor MG2 because the torque for rotating the rotors of the motors MG1 and MG2 is not output and the copper of the three-phase coil of the motors MG1 and MG2 is output. This is because power is consumed due to loss. By such control, the electric charge stored in the capacitor 57 can be discharged without using a discharging resistor.

  When the discharge to the motor MG1 or the motor MG2 is started in this way, the measurement of the time during which the discharge continues (discharge duration T) is started (step S160), and the voltage V between terminals of the capacitor 57 measured by the voltage sensor 57a. Until the value becomes 0 (steps S170 and S180), the control of flowing the constant current I as the d-axis current to the three-phase coil of the motor MG1 or MG2 is stopped (step S190), and the measured discharge duration T and The set threshold value Tref is compared (step S200). When the discharge duration time T is equal to or greater than the threshold value Tref, the capacitor 57 is determined to be normal (step S210), and when the discharge duration time T is less than the threshold value Tref, the capacitor 57 is abnormal. Is determined (step S220), and the abnormality determination routine is terminated. Here, when the discharge duration T is less than the threshold value Tref, it can be considered that the capacitance C of the capacitor 57 is lower than that in the normal state and the stored charge is reduced. Therefore, the discharge duration T is defined as the threshold value Tref. By comparing, the abnormality of the capacitor 57 can be determined more appropriately.

  According to the drive system 20 of the embodiment described above, when an overcurrent flows through either of the inverters 41 and 42 or when an overvoltage occurs in the voltage between terminals of the capacitor 57, the charge stored in the capacitor 57 is stored. Is discharged to the motor MG1 or the motor MG2 with the constant current I, and the discharge duration time T is compared with the threshold value Tref, whereby the abnormality of the capacitor 57 can be determined more appropriately. In addition, since the constant current I flows as the d-axis current, it is possible to determine the abnormality of the capacitor 57 by consuming electric power without generating torque in the motors MG1 and MG2. Furthermore, since the electric charge stored in the capacitor 57 is discharged to the motor MG1 or the motor MG2 to consume electric power, it is possible to determine the abnormality of the capacitor 57 without using a discharging resistor.

  In the drive system 20 of the embodiment, the threshold Tref as the discharge time used for determining the abnormality of the capacitor 57 is set by subtracting the predetermined time α from the discharge calculation time Tcal, but the predetermined time α is set to the value 0. It is good also as what uses discharge calculation time Tcal as what is set, ie, threshold value Tref.

  In the drive system 20 of the embodiment, the d-axis current flows through the three-phase coils of the motor MG1 or the motor MG2, and the charge stored in the capacitor 57 is consumed. However, the drive system 20 is not limited to the d-axis current. As long as a constant current flows, it is sufficient.

  In the drive system 20 of the embodiment, the two motors MG1 and MG2 are provided via the inverters 41 and 42. However, the drive system 20 may be provided with one motor, or may be provided with three or more motors.

  In the drive system 20 of the embodiment, the power of the battery 50 is supplied to the inverters 41 and 42 via the system main relay 56. However, as illustrated in the drive system 120 of the modified example of FIG. 42 positive and negative buses 54a and 54b, two transistors T31 and T32 arranged in series so as to be in parallel with the smoothing capacitor 57, and two diodes D31 and D32 attached to hold a voltage in parallel with each transistor. And a reactor L attached to the middle of the two transistors T31 and T32 and the positive side of the battery 50 via a system main relay 56, and a reactor L on the system main relay 56 side of the booster circuit 80. And a smoothing capacitor 58 connected to the negative electrode bus 54b; A voltage sensor 58a that detects the voltage of the capacitor 58, may be as comprising. In this case, in the process of step S120 of the abnormality determination routine of FIG. 2, the discharge calculation time Tcal is based on the capacitances C1 and C2 of the capacitors 57 and 58, the voltages V1 and V2 detected by the voltage sensors 57a and 58a, and the constant current I. What is calculated by the following equation (3) can be used. Thereby, it can be determined that at least one of the capacitors 57 and 58 is abnormal.

Tcal = (C1 ・ V1 + C2 ・ V2) / I (3)

  In the embodiment, the drive system 20 has been described. However, a capacitor abnormality determination method provided in such a drive system may be used.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motors MG1 and MG2 correspond to “motors”, the inverters 41 and 42 correspond to “inverter circuits”, the battery 50 and the system main relay 56 correspond to “power supply circuits”, and the capacitor 57 When the voltage sensor 57a corresponds to the “voltage detection means” and outputs one of the overcurrent errors Finv1 and Finv2 or the overvoltage error OV, the system main relay 56 is turned off, A threshold value Tref is set based on the capacitance C of the capacitor 57 and the voltage V and the constant current I when the system main relay 56 is turned off. The constant current I is set as the d-axis current in the motor on the inverter side without an overcurrent error. The inverter 41 or the inverter 42 is subjected to switching control until the voltage V becomes a value 0 so that the voltage V becomes 0. The electronic control unit 70 that executes the processing of steps S100 to S220 of the abnormality determination routine of FIG. 2 that compares the time until the threshold value Tref with the set threshold value Tref to determine abnormality of the capacitor 57 corresponds to “capacitor abnormality determination means”. To do. Here, the “motor” is not limited to the motors MG1 and MG2 configured as well-known synchronous generator motors, and may be any type of motor such as an induction motor. The “inverter circuit” is not limited to the inverters 41 and 42, and may be any circuit as long as it drives an electric motor. The “power supply circuit” is not limited to the one provided with the battery 50 and the system main relay 56, and a DC power supply for supplying power to the inverter circuit and a blocking means for cutting off the connection between the DC power supply and the inverter circuit; As long as it has, it does not matter. The “capacitor” is not limited to the capacitor 57 that is connected between the positive electrode bus 54a and the negative electrode bus 54b and smoothes the voltage, but may be any capacitor as long as it is connected between the output terminals of the power supply circuit. I do not care. The “voltage detection means” is not limited to the voltage sensor 57a attached to the positive electrode bus 54a and the negative electrode bus 54b, but may be any device as long as it detects the voltage across the terminals of the capacitor. As the “capacitor abnormality determining means”, when the electronic control unit 70 outputs one of the overcurrent errors Finv1 and Finv2 or the overvoltage error OV, the system main relay 56 is turned off and the capacitance C of the capacitor 57 is set. The threshold value Tref is set based on the voltage V and the constant current I when the system main relay 56 is turned off, and the inverter 41 so that the constant current I flows as a d-axis current to the motor on the inverter side without an overcurrent error. Alternatively, the inverter 42 is subjected to switching control until the voltage V reaches the value 0, and the time until the voltage V reaches the value 0 is compared with the set threshold value Tref to determine the abnormality of the capacitor 57 in the abnormality determination routine of FIG. It is not limited to the electronic control unit 70 that executes the processes of steps S100 to S220. When the inverter circuit is controlled so that a predetermined current flows to the motor when the connection between the DC power source and the inverter circuit is interrupted by the shut-off means when an abnormality occurs in the inverter circuit or when an overvoltage is detected by the voltage detecting means Any capacitor may be used as long as it determines the abnormality of the capacitor based on the discharge duration time during which the predetermined current can be passed. The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. It is an example for specifically explaining the best mode for doing so, and does not limit the elements of the invention described in the column of means for solving the problem. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention can be used in the manufacturing industry of drive devices.

It is a block diagram which shows the outline of a structure of the drive system 20 as one Example of this invention. 4 is a flowchart illustrating an example of an abnormality determination routine that is executed by an electronic control unit 70 of the drive system 20. It is a block diagram which shows the outline of a structure of the drive system 120 of a modification.

Explanation of symbols

  20, 120 drive system, 41, 42 inverter, 45U, 45V, 45W, 46U, 46V, 46W current sensor, 50 battery, 54 power line, 54a positive bus, 54b negative bus, 56 system main relay, 57, 58 capacitor, 57a, 58a voltage sensor, 70 electronic control unit, 72 CPU, 74 ROM, 76 RAM, 80 booster circuit, MG1, MG2 motor, D11-D16, D21-D26, D31, D32 diode, T11-T16, T21-T26, T31, T32 Transistor, L reactor.

Claims (6)

A power supply circuit having an electric motor, an inverter circuit for driving the electric motor, a DC power supply for supplying electric power to the inverter circuit, and a shut-off means for cutting off the connection between the DC power supply and the inverter circuit; and an output of the power supply circuit A drive device comprising a capacitor connected between the terminals,
Voltage detecting means for detecting a voltage between terminals of the capacitor;
When an abnormality occurs in the inverter circuit or when an overvoltage is detected by the voltage detection means, a predetermined current flows to the motor in a state where the connection between the DC power source and the inverter circuit is cut off by the interruption means. Capacitor abnormality determining means for determining abnormality of the capacitor based on a discharge duration time during which the predetermined current was able to flow when the inverter circuit was controlled;
A drive device comprising:   The capacitor abnormality determining means has a voltage detected by the voltage detecting means when starting the flow of the predetermined current to the motor as V, a capacitance of the capacitor as C, and a predetermined current as I. 2. The driving apparatus according to claim 1, wherein the capacitor is determined to be abnormal when the discharge duration is less than a time based on T calculated by T = CV / I.   3. The drive device according to claim 1, wherein the capacitor abnormality determination unit is a unit that controls the inverter circuit so that the predetermined current flows as a d-axis current to the electric motor. The drive device according to any one of claims 1 to 3,
The electric motor is a plurality of electric motors,
The inverter circuit is a plurality of inverter circuits for the plurality of electric motors;
The capacitor abnormality determination means uses the inverter circuit in which no abnormality has occurred among the plurality of inverter circuits when the abnormality has occurred in any of the plurality of inverter circuits, and the abnormality has not occurred in the predetermined current. A means for controlling the inverter circuit in which the abnormality does not occur so as to flow to the electric motor corresponding to the inverter circuit.
Drive device.   5. The drive device according to claim 1, wherein the power supply circuit is a circuit having a booster circuit that boosts power of the DC power supply and supplies the boosted power to the inverter circuit. 6. A power supply circuit having an electric motor, an inverter circuit for driving the electric motor, a DC power supply for supplying electric power to the inverter circuit, and a shut-off means for cutting off the connection between the DC power supply and the inverter circuit; and an output of the power supply circuit An abnormality determination method for determining abnormality of the capacitor in a driving device including a capacitor connected between terminals,
When an abnormality occurs in the inverter circuit or when an overvoltage occurs in the capacitor, the inverter is configured such that a predetermined current flows through the motor in a state where the connection between the DC power source and the inverter circuit is interrupted by the interrupting means. Discharge calculated based on a voltage between terminals of the capacitor and a capacitance of the capacitor when the predetermined duration of current when the circuit was controlled was able to flow the predetermined current starts to flow to the electric motor Determining that the capacitor is abnormal when it is shorter than a time based on a calculation time;
An abnormality determination method characterized by the above.

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