JP2012044847A - Motor controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a motor controller where a current does not flow in a motor when a smoothing capacitor is discharged.SOLUTION: The motor controller includes: the smoothing capacitors; an inverter circuit; and a control circuit. The inverter circuit is constituted by connecting in parallel three switching circuits 110 to 112 consisting of two IGBT connected in series. In each of the switching circuits 110 to 112, one end is connected to one end of the smoothing capacitor and an other end is connected to an other end of the smoothing capacitor. When the smoothing capacitor is discharged, the control circuit turns off the switching circuit 110, turns on the switching circuits 111 and 112 and discharges the smoothing capacitor 10. The control circuit 12 fully turns on IGBT 111a and 112a at one end side of the switching circuits 111 and 112 and synchronously turns on/off IGBT 111b and 112b on the other end side. Thus, the current flowing in the motor can be suppressed when the smoothing capacitor is discharged.

Description

  The present invention relates to a motor control device including a smoothing capacitor and a power conversion circuit configured by a switching element.

  2. Description of the Related Art Conventionally, as a motor control device including a smoothing capacitor and a power conversion circuit configured by a switching element, for example, there is a power conversion device disclosed in Patent Document 1.

  This power conversion device includes a smoothing capacitor, a power conversion circuit, and a control device. One end of the smoothing capacitor is connected to the positive terminal of the DC power source, and the other end of the smoothing capacitor is connected to the negative terminal of the DC power source. The power conversion circuit is configured by connecting three sets of legs composed of two switching elements connected in series in parallel. One end of the leg is connected to one end of the smoothing capacitor, and the other end of the leg is connected to the other end of the smoothing capacitor. The series connection point of the two switching elements forming the leg is connected to the electric motor. The control device is connected to each switching element.

  This power conversion device converts a DC voltage output from a DC power source into an AC voltage and supplies it to an electric motor. When the power conversion device starts operation, electric charges are accumulated in the smoothing capacitor, and the DC voltage output from the DC power supply is smoothed. After that, when the power conversion device stops operating, the charge remains accumulated in the smoothing capacitor. Therefore, there is a possibility of electric shock due to the electric charge accumulated in the smoothing capacitor. However, the control device turns on all the switching elements for a predetermined time during which no overcurrent occurs. Thereby, the electric charge accumulated in the smoothing capacitor can be discharged. Therefore, an electric shock can be prevented.

JP 2009-232620 A

  In the power conversion device described above, all the switching elements are turned on for a predetermined time to discharge the charge accumulated in the smoothing capacitor. However, just before all the switching elements are turned on due to timing differences, the switching element on one end side of one leg connected to the positive end of the DC power supply and the other leg connected to the negative end of the DC power supply If only the switching element on the other end side is turned on, a current that should not flow originally flows to the electric motor. In this case, the electric motor may rotate.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a motor control device in which no current flows through the motor when the smoothing capacitor is discharged.

  In view of this, the present inventor has conducted intensive research to solve this problem, and as a result of repeated trial and error, at least two switching elements on one end side and the other end side of the at least two switching circuits that discharge the charge accumulated in the smoothing capacitor. It was found that the current flowing to the motor can be suppressed during the discharge of the smoothing capacitor by turning on or off one of them synchronously, and the present invention has been completed.

  That is, the power conversion device according to claim 1 is configured by connecting in parallel a plurality of switching circuits each including a smoothing capacitor that smoothes a DC voltage and two switching elements connected in series, and one end of the switching circuit is smoothed. The other end of the switching circuit is connected to one end of the capacitor, the other end of the smoothing capacitor, and the series connection point of two switching elements forming the switching circuit is connected to the motor, and the switching element is controlled. A control circuit, wherein the control circuit turns on two switching elements forming the switching circuit by at least two switching circuits and discharges the electric charge accumulated in the smoothing capacitor. At least two switches that discharge the charge stored in the capacitor Synchronously on at least one of one end and the other end of the switching element of the road, characterized by off.

  According to this configuration, the control circuit turns on the two switching elements forming the switching circuit by at least two switching circuits to discharge the electric charge accumulated in the smoothing capacitor. Moreover, at least one of the switching elements on one end side and the other end side of these switching circuits is turned on and off in synchronization. Therefore, unlike the prior art, only the switching element on one end side of one switching circuit and the switching element on the other end side of another switching circuit are not turned on. Therefore, the current flowing through the motor can be suppressed when the smoothing capacitor is discharged.

  The power conversion device according to claim 2 is characterized in that the control circuit controls the switching elements so that the discharge currents flowing in at least two switching circuits for discharging the charge accumulated in the smoothing capacitor are equal.

  According to this configuration, the switching element is damaged when it generates heat exceeding the allowable range. The heat generation of the switching element is proportional to the power consumption of the switching element, that is, the product of the current flowing through the switching element and the voltage between the terminals. However, the control circuit controls the switching element so that the discharge currents flowing in at least two switching circuits that discharge the charge accumulated in the smoothing capacitor are equal. Therefore, the heat generation of the switching elements forming these switching circuits can be equalized. Accordingly, it is possible to prevent the switching element from being damaged due to the bias of heat generation.

  The power conversion device according to claim 3, wherein the control circuit discharges the electric charge accumulated in the smoothing capacitor, the voltage between terminals of the switching element on one end side of at least two switching circuits, and the switching element on the other end side. The switching element is controlled so that at least one of the terminal voltages becomes equal.

  According to this configuration, the switching element is damaged when it generates heat exceeding the allowable range. The heat generation of the switching element is proportional to the power consumption of the switching element, that is, the product of the current flowing through the switching element and the voltage between the terminals. However, in the control circuit, at least one of the terminal voltage of the switching element on one end side of the at least two switching circuits that discharges the electric charge accumulated in the smoothing capacitor and the terminal voltage of the switching element on the other end side are equal. The switching element is controlled so that Therefore, the heat generation of the switching elements forming these switching circuits can be equalized. Accordingly, it is possible to prevent the switching element from being damaged due to the bias of heat generation.

  The power conversion device according to claim 4, wherein the control circuit discharges the electric charge accumulated in the smoothing capacitor, the power consumption of the switching element on one end side of at least two switching circuits, and the consumption of the switching element on the other end side. The switching element is controlled so that at least one of the electric power becomes equal.

  According to this configuration, the switching element is damaged when it generates heat exceeding the allowable range. The heat generation of the switching element is proportional to the power consumption of the switching element. However, the control circuit is configured such that at least one of the power consumption of the switching element on one end side of the at least two switching circuits for discharging the charge accumulated in the smoothing capacitor and the power consumption of the switching element on the other end side become equal. The switching element is controlled. Therefore, the heat generation of the switching elements forming these switching circuits can be equalized. Accordingly, it is possible to prevent the switching element from being damaged due to the bias of heat generation.

  According to a fifth aspect of the present invention, the control circuit is configured to control the temperature of the switching element on one end side of the at least two switching circuits for discharging the charge accumulated in the smoothing capacitor and the temperature of the switching element on the other end side. The switching element is controlled so that at least one of them is equal.

  According to this configuration, the switching element is damaged when it generates heat exceeding the allowable range. However, the control circuit switches so that at least one of the temperature of the switching element on one end of the at least two switching circuits that discharges the electric charge accumulated in the smoothing capacitor and the temperature of the switching element on the other end are equal. Control the element. Therefore, the heat generation of the switching elements forming these switching circuits can be equalized. Accordingly, it is possible to prevent the switching element from being damaged due to the bias of heat generation.

  The power conversion device according to claim 6 controls a vehicle driving motor. According to this configuration, in the power conversion device that controls the motor for driving the vehicle, the current flowing through the motor can be suppressed when the smoothing capacitor is discharged.

It is a circuit diagram of the motor control device in the present embodiment. It is a timing chart which shows the switching state of IGBT at the time of smoothing capacitor discharge. It is a timing chart which shows the switching state of IGBT at the time of the smoothing capacitor discharge in another form.

  Next, an embodiment is given and this invention is demonstrated in detail. In the present embodiment, an example in which the motor control device according to the present invention is applied to a motor control device that is mounted on a vehicle and controls a vehicle driving motor is shown.

  First, the configuration of the motor control device of this embodiment will be described with reference to FIG. Here, FIG. 1 is a circuit diagram of the motor control device according to the present embodiment.

  A motor control device 1 shown in FIG. 1 converts a DC high voltage (for example, 288V) output from a high voltage battery B1 insulated from a vehicle body into a three-phase AC voltage, and supplies it to a vehicle drive motor M1 for vehicle drive. It is a device for controlling the motor M1. The motor control device 1 includes a smoothing capacitor 10, an inverter circuit 11 (power conversion circuit), and a control circuit 12.

  The smoothing capacitor 10 is an element for smoothing the DC high voltage of the high voltage battery B1. One end of the smoothing capacitor 10 is connected to the positive terminal of the high voltage battery B1 via the relay R10. Moreover, the other end is connected to the negative electrode end of the high voltage battery B1 via the relay R11.

  The inverter circuit 11 is a circuit that converts the DC voltage smoothed by the smoothing capacitor 10 into a three-phase AC voltage and supplies it to the vehicle drive motor M1. Further, it is also a circuit for discharging the electric charge accumulated in the smoothing capacitor 10. The inverter circuit 11 includes three switching circuits 110 to 112 (a plurality of switching circuits) and current sense resistors 113 to 115.

  The switching circuit 110 is a circuit that converts a DC voltage into an AC voltage by turning on and off. Further, it is also a circuit that discharges the electric charge accumulated in the smoothing capacitor 10 by being turned on. The switching circuit 110 includes two IGBTs 110a and 110b (switching elements). The IGBT 110b includes a current sense terminal through which a current that is proportional to the collector current and smaller than the collector current flows. The IGBTs 110a and 110b are connected in series. Specifically, the emitter of the IGBT 110a is connected to the collector of the IGBT 110b.

  The switching circuit 111 is a circuit that converts a DC voltage into an AC voltage by turning on and off. Further, it is also a circuit that discharges the electric charge accumulated in the smoothing capacitor 10 by being turned on. The switching circuit 111 includes two IGBTs 111a and 111b (switching elements). The IGBT 111b has a current sense terminal through which a current that is proportional to the collector current and smaller than the collector current flows. The IGBTs 111a and 111b are connected in series. Specifically, the emitter of the IGBT 111a is connected to the collector of the IGBT 111b.

  The switching circuit 112 is a circuit that converts a DC voltage into an AC voltage by turning on and off. Further, it is also a circuit that discharges the electric charge accumulated in the smoothing capacitor 10 by being turned on. The switching circuit 112 includes two IGBTs 112a and 112b (switching elements). The IGBT 112b includes a current sense terminal through which a current that is proportional to the collector current and smaller than the collector current flows. The IGBTs 112a and 112b are connected in series. Specifically, the emitter of the IGBT 112a is connected to the collector of the IGBT 112b.

  The three switching circuits 110 to 112 are connected in parallel (a plurality of parallel connections). Specifically, the collectors of the IGBTs 110a to 112a that are one end of the switching circuits 110 to 112 and the emitters of the IGBTs 110b to 112b that are the other ends of the switching circuits 110 to 112 are respectively connected. The collectors of the IGBTs 110 a to 112 a are connected to one end of the smoothing capacitor 10, and the emitters of the IGBTs 110 b to 112 b are connected to the other end of the smoothing capacitor 10, respectively. The gates and emitters of the IGBTs 110a, 110b, 111a, 111b, 112a, 112b are connected to the control circuit 12, respectively. Further, the series connection points of the IGBTs 110a and 110b, the IGBTs 111a and 111b, and the IGBTs 112a and 112b that are connected in series are respectively connected to the vehicle driving motor M1.

  The current sense resistors 113 to 115 are elements for detecting a discharge current flowing through the switching circuits 110 to 112 when the smoothing capacitor 10 is discharged. Specifically, it is an element that converts a current flowing through a current sense terminal into a voltage. One ends of the current sense resistors 113 to 115 are connected to the current sense terminals of the IGBTs 110b to 112b, and the other ends are connected to the emitters of the IGBTs 110b to 1120b. Further, both ends of the current sense resistors 113 to 115 are connected to the control circuit 12 respectively.

  The control circuit 12 is a circuit that controls the switching circuits 110 to 112. Specifically, this is a circuit for controlling the IGBTs 110a, 110b, 111a, 111b, 112a, 112b. The control circuit 12 is connected to the gates and emitters of the IGBTs 110a, 110b, 111a, 111b, 112a, and 112b. The current sense resistors 113 to 115 are connected to both ends, respectively.

  Next, the operation of the motor control device will be described with reference to FIGS. Here, FIG. 2 is a timing chart showing the switching state of the IGBT during smoothing capacitor discharge.

  When an ignition switch (not shown) of the vehicle is turned on, relays R10 and R11 shown in FIG. 1 are turned on, and the motor control device 1 starts operating. When the relays R10 and R11 are turned on, the DC high voltage of the high voltage battery B1 is smoothed by the smoothing capacitor 10. The control circuit 12 controls the switching circuits 110 to 112 constituting the inverter circuit 11 based on a command input from the outside. Specifically, the IGBTs 110a, 110b, 111a, 111b, 112a, and 112b are controlled. The inverter circuit 11 converts the DC high voltage smoothed by the smoothing capacitor 10 into a three-phase AC voltage and supplies it to the vehicle drive motor M1. In this way, the motor control device 1 controls the vehicle drive motor M1.

  Thereafter, when the ignition switch is turned off, the relays R10 and R11 are turned off. The motor control device 1 stops the supply of voltage to the vehicle drive motor M1. When the supply of the voltage to the vehicle drive motor M1 is stopped, the electric charge is accumulated in the smoothing capacitor 10.

  The control circuit 12 turns off the two IGBTs 110a and 110b constituting the switching circuit 110. Then, the two IGBTs 111 a and 111 b constituting the switching circuit 111 are turned on, and the two IGBTs 112 a and 112 b constituting the switching circuit 112 are turned on to discharge the electric charge accumulated in the smoothing capacitor 10. At this time, as shown in FIG. 2, the control circuit 12 fully turns on the IGBTs 111 a and 112 a on one end side of the switching circuits 111 and 112, and turns on and off the IGBTs 111 b and 112 b on the other end side multiple times in synchronization.

  The control circuit 12 detects the discharge current flowing through the switching circuits 111 and 112 based on the voltages of the current sense resistors 114 and 115. Then, the IGBTs 111a, 111b, 112a, and 112b are controlled so that the discharge currents flowing through the two switching circuits 111 and 112 become equal. Specifically, the IGBTs 111a and 112a are fully turned on, and are turned on and off synchronously while adjusting the gate voltages of the IGBTs 110b and 112b.

  As a result, the charges accumulated in the smoothing capacitor 10 are discharged by the switching circuits 111 and 112. Therefore, electric shock due to the electric charge accumulated in the smoothing capacitor 10 can be prevented.

  Next, the effect will be described. According to the present embodiment, the control circuit 12 turns on the two IGBTs 111 a and 111 b constituting the switching circuit 111 and turns on the two IGBTs 112 a and 112 b constituting the switching circuit 112 and accumulates them in the smoothing capacitor 10. Discharge the charge. In addition, the IGBTs 111b and 112b on the other end side of the switching circuits 111 and 112 are turned on and off in synchronization. Therefore, only the IGBT 111a on one end side of the switching circuit 111 and the IGBT 112b on the other end side of the switching circuit 112 are not turned on. Further, only the IGBT 112a on one end side of the switching circuit 112 and the IGBT 111b on the other end side of the switching circuit 111 are not turned on. Therefore, in the motor control device 1 that controls the vehicle drive motor M1, it is possible to suppress the current flowing through the vehicle drive motor M1 when the smoothing capacitor 10 is discharged.

  Further, according to the present embodiment, the IGBT is damaged when it generates heat exceeding the allowable range. The heat generation of the IGBT is proportional to the power consumption of the IGBT, that is, the product of the current flowing through the IGBT and the voltage between the terminals. However, the control circuit 12 controls the IGBTs 111a, 111b, 112a, and 112b so that the discharge currents flowing through the two switching circuits 111 and 112 become equal. Therefore, the heat generation of the IGBTs 111a, 111b, 112a, 112b forming the switching circuits 111, 112 can be equalized. Therefore, it is possible to prevent the IGBT from being damaged due to the uneven heat generation.

  In the present embodiment, when the smoothing capacitor 10 is discharged, the control circuit 12 fully turns on the IGBTs 111a and 112a on one end side of the switching circuits 111 and 112 and simultaneously turns on and off the IGBTs 111b and 112b on the other end side. However, this is not a limitation. As shown in FIG. 3, the one end side and the other end side are interchanged so that the IGBTs 111 b and 112 b on the other end side of the switching circuits 111 and 112 are fully turned on, and the IGBTs 111 a and 112 a on one end side are turned on and off in synchronization. May be. Further, the IGBTs 111a and 112a on one end side of the switching circuits 111 and 112 and the IGBTs 111b and 112b on the other end side may be turned on and off in synchronization with each other. It suffices that at least one of the switching elements on one end side and the other end side of the switching circuit is turned on and off in synchronization.

  In the present embodiment, an example in which the electric charge accumulated in the smoothing capacitor 10 is discharged by the two switching circuits 111 and 112 is described, but the present invention is not limited to this. It may be discharged by the two switching circuits 110 and 111, or may be discharged by the two switching circuits 110 and 112. Moreover, you may discharge by the three switching circuits 110-112. What is necessary is just to discharge by at least two switching circuits.

  Furthermore, in this embodiment, although the example which controls IGBT111a, 111b, 112a, 112b so that the discharge current which flows into the two switching circuits 111,112 becomes equal is given, it is not restricted to this. The collector-emitter voltage (terminal voltage) of the IGBT on one end side of the at least two switching circuits that discharge the electric charge accumulated in the smoothing capacitor 10 and the collector-emitter voltage (terminal voltage) of the IGBT on the other end side. The IGBT may be controlled such that at least one of the above is equal. Further, the IGBT is controlled so that at least one of the power consumption of the IGBT on one end side of the at least two switching circuits for discharging the electric charge accumulated in the smoothing capacitor and the power consumption of the IGBT on the other end side become equal. It may be. Here, the power consumption can be obtained from the current flowing through the IGBT and the collector-emitter voltage. Further, the IGBT is controlled so that at least one of the temperature of the IGBT on one end side of the at least two switching circuits for discharging the electric charge accumulated in the smoothing capacitor and the temperature of the IGBT on the other end side becomes equal. Also good.

  An IGBT breaks when it generates heat exceeding an allowable range. The heat generation of the IGBT is proportional to the power consumption of the IGBT, that is, the product of the current flowing through the IGBT and the voltage between the terminals. Therefore, in any case, it is possible to equalize the heat generation of the IGBT forming the switching circuit that discharges the smoothing capacitor. Therefore, it is possible to prevent the IGBT from being damaged due to the uneven heat generation.

  In this case, considering the heat generation of the IGBT, the IGBT may be controlled so that the discharge current, the voltage between terminals, the power consumption, or the temperature is within an allowable range.

  In addition, in the present embodiment, an example of the inverter circuit 11 configured by connecting the three switching circuits 110 to 112 in parallel is given as the power conversion circuit, but is not limited thereto. Any power conversion circuit configured by connecting a plurality of switching circuits in parallel may be used.

DESCRIPTION OF SYMBOLS 1 ... Motor control apparatus, 10 ... Smoothing capacitor, 11 ... Inverter circuit (power conversion circuit), 110-112 ... Switching circuit, 110a, 110b, 111a, 111b, 112a, 112b ... IGBT (switching element), 113-115 ... current sense resistor, 12 ... control circuit, B1 ... high voltage battery, M1 ... vehicle drive motor, R10, R11 ... relay

Claims (6)

A smoothing capacitor that smoothes the DC voltage;
A plurality of switching circuits composed of two switching elements connected in series are connected in parallel. One end of the switching circuit is connected to one end of the smoothing capacitor, and the other end of the switching circuit is connected to the other end of the smoothing capacitor. And a power conversion circuit in which a series connection point of the two switching elements forming the switching circuit is connected to a motor;
A control circuit for controlling the switching element;
In the motor control device, wherein the control circuit turns on the two switching elements forming the switching circuit and discharges the electric charge accumulated in the smoothing capacitor by at least two of the switching circuits.
The control circuit synchronously turns on and off at least one of the switching elements on one end side and the other end side of the at least two switching circuits that discharge the charge accumulated in the smoothing capacitor. Motor control device.   2. The motor control according to claim 1, wherein the control circuit controls the switching element so that discharge currents flowing in at least two of the switching circuits for discharging the charge accumulated in the smoothing capacitor are equal. apparatus.   The control circuit includes at least one of a voltage between terminals of the switching element on one end side of at least two switching circuits and a voltage between terminals of the switching element on the other end side that discharge electric charges accumulated in the smoothing capacitor. The motor control device according to claim 1, wherein the switching elements are controlled so that the two are equal.   The control circuit includes at least one of power consumption of the switching element on one end side of at least two switching circuits for discharging the charge accumulated in the smoothing capacitor and power consumption of the switching element on the other end side. The motor control device according to claim 1, wherein the switching elements are controlled to be equal.   In the control circuit, at least one of the temperature of the switching element on one end side of the at least two switching circuits for discharging the charge accumulated in the smoothing capacitor and the temperature of the switching element on the other end side become equal. The motor control device according to claim 1, wherein the switching element is controlled as described above.   The motor control device according to claim 1, wherein the motor for driving the vehicle is controlled.

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