JP5105154B2 - Control device - Google Patents

Description

  The present invention relates to the discharge of charge accumulated in a smoothing capacitor of a voltage conversion circuit that converts the amplitude of a voltage of a power supply.

  In a hybrid vehicle, a fuel cell vehicle, an electric vehicle, and the like, a driving force is generated and transmitted to an axle by a generator / motor (hereinafter abbreviated as an electric motor or a motor). In order to obtain the optimum driving force according to the running state of the vehicle, the power supply voltage of the battery is boosted to a desired voltage by the step-up / down converter, and converted to DC / 3-phase AC by the inverter based on the boosted voltage, The driving force of the motor is obtained. Also, the kinetic energy transmitted from the axle to the electric motor is converted into electric energy, three-phase AC / DC conversion is performed by an inverter, and the voltage is stepped down by a step-up / down converter and regenerated to the battery. In order to keep the boosted voltage constant, a smoothing capacitor is provided in parallel with a load such as an electric motor. In such a configuration, it is necessary to discharge the electric charge accumulated in the smoothing capacitor when the vehicle or the like is stopped in order to ensure the safety of the worker during maintenance.

Conventionally, there is Patent Document 1 as a prior art for discharging the electric charge accumulated in the smoothing capacitor. In Patent Document 1, the upper and lower switching elements constituting the upper and lower arms of the buck-boost converter connected in parallel to the smoothing capacitor are simultaneously turned on, the upper and lower switching elements are short-circuited, and the switching loss and conduction in the switching elements Electric charges accumulated in the smoothing capacitor are discharged by Joule heat due to loss.
Japanese Patent Laid-Open No. 2005-229689

  In the conventional discharge of the smoothing capacitor, the upper and lower switching elements are short-circuited, so that a large inrush current flows from the high (H) side to the low (L) side to the upper and lower switching elements, and the upper and lower switching elements generate heat. The amount increases, and this affects the life of each component such as a capacitor terminal to which a switching element and a smoothing capacitor are connected.

  The present invention has been made in view of the above problems, and does not short-circuit the upper and lower arms to discharge the electric charge of the smoothing capacitor, but rather suppresses the discharge current and the amount of heat generated, thereby adversely affecting the life of the component. An object of the present invention is to provide a control device that can suppress the effect.

According to the first aspect of the present invention, the power supply, the load, the voltage conversion circuit that converts the amplitude of the voltage of the power supply, and the interruption on the power supply side that implements or cuts off the power supply from the power supply to the voltage conversion circuit. The voltage conversion circuit includes a plurality of switching elements and a plurality of reactors, and a smoothing capacitor connected in parallel to the load, the smoothing capacitor and the plurality of the A first closed circuit is configured by turning on the switching element from the switching element and one or more of the reactors, and the switching element is turned on from the smoothing capacitor, the plurality of switching elements, and one or more of the reactors. As a result, a second closed circuit different from the first closed circuit is formed, and the voltage change is performed from the power source by the connecting / disconnecting means on the power source side. When power supply to the circuit is interrupted, the energized while sequentially changing the second closed circuit with the first closed circuit by on-off operation of the switching element, said voltage conversion circuit, each reactor A plurality of the switching elements are provided on each of the high potential side and the low potential side as viewed from above, and the switching elements on the low potential side as viewed from the reactor are turned on prior to the switching elements on the high potential side. Thus, there is provided a control device comprising the first and second closed circuits, wherein the low-potential side switching element is turned off after the high-potential side switching element is turned off. .

  According to a second aspect of the present invention, in the first aspect of the invention, the voltage conversion circuit further includes connection / disconnection means on the load side for performing or cutting off power supply from the voltage conversion circuit to the load, When the power supply from the power source to the load is interrupted by the power source side connecting / disconnecting means and the load side connecting / disconnecting means, the first closed circuit and the first closed circuit are turned on and off by the switching elements. A control device is provided in which the two closed circuits are sequentially changed and energized.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the voltage conversion circuit includes a plurality of the switching elements on each of a high potential side and a low potential side as viewed from each reactor. A plurality of the switching elements on one of the high potential side and the low potential side are simultaneously turned on, and one or more of the switching elements on the other side are turned on, whereby the first and second closings are performed. A control device is provided that comprises a circuit.

According to a fourth aspect of the present invention, there is provided the control device according to any one of the first to third aspects, wherein the switching element is turned on and off every predetermined time. .

According to a fifth aspect of the present invention, there is provided the control device according to the second aspect, wherein the load side connecting / disconnecting means is an inverter and the load is an electric motor.

According to the invention described in claim 6, in the invention described in any one of claims 1 to 5 , the first and second closed circuits include diodes connected in parallel to the switching elements. The voltage conversion circuit is provided with a control device that is a boost converter that boosts the voltage of the power supply and supplies the boosted voltage to the load side.

According to the first aspect of the present invention, when the power supply from the power source to the voltage conversion circuit is interrupted by the connecting / disconnecting means on the power source side, the first closed circuit and the second closed circuit are turned on and off by the switching element. Since the current is sequentially changed, the electric charge accumulated in the smoothing capacitor is discharged through the plurality of switching elements and reactors in the first and second closed circuits that are energized, and a discharge current flows, and is discharged by the inductance of the reactor. Current is suppressed. Also, the release of Joule heat due to the resistance of the reactor and the magnetic energy accumulated in the reactor are released into the atmosphere, the current flowing through the switching element is suppressed, the stress of the switching element can be reduced, and the switching element due to discharge Adversely affecting the lifespan of the product. Further, the voltage conversion circuit is provided with a plurality of switching elements on each of the high potential side and the low potential side as viewed from each reactor, and the switching element on the low potential side as viewed from the reactor is replaced with each switching element on the high potential side. Therefore, when the high-potential side switching element is turned on, the low-potential side switching element is already on, and a closed circuit including the ON high-potential side switching element is configured. The discharge current flows from the smoothing capacitor to the closed circuit. If the switching element on the low potential side remains OFF when the switching element on the high potential side is turned ON, the power supply side is disconnected from the voltage conversion circuit by the connecting / disconnecting means on the power supply side. In addition, a high potential is applied from the smoothing capacitor, and a high-voltage component is required for the power supply side components such as the connecting / disconnecting means. However, since the discharge current flows from the smoothing capacitor to the closed circuit, the voltage is lowered by the reactor constituting the closed circuit, and the power supply side components such as the connecting / disconnecting means may have a lower withstand voltage.

  According to the second aspect of the present invention, when the power supply from the power source to the load is interrupted by the power source side connecting / disconnecting means and the load side connecting / disconnecting means, the first closed circuit is turned on and off by each switching element. Since the second closed circuit is sequentially changed and energized, it is possible to prevent undesired power from being supplied to the power source or the load side.

  According to the third aspect of the present invention, a plurality of switching elements on either the high-potential side or the low-potential side are simultaneously turned on, and one or more switching elements on the other side are turned on. Therefore, the discharge current flows from the high potential side that is turned ON simultaneously to the low potential side, or from the high potential side to the low potential side that is turned ON simultaneously. And the discharge time can be shortened.

According to the fourth aspect of the invention, since the switching elements are turned on and off at regular intervals every predetermined time, heat, stress and the like can be equalized for each switching element and reactor.

According to the invention of claim 5 , since the load side connecting / disconnecting means is an inverter and the load is an electric motor, when discharging the electric charge accumulated in the smoothing capacitor, all the switching elements of the inverter are turned OFF. Thus, power supply from the voltage conversion circuit to the electric motor is interrupted, and it is possible to prevent undesired torque from being supplied to the electric motor.

According to a sixth aspect of the present invention, the first and second closed circuits include diodes connected in parallel to the switching elements, and the voltage conversion circuit boosts the voltage of the power source and loads the boosted voltage to the load. Since the step-up converter is supplied to the side, the current flowing through the switching element is suppressed in the step-up converter, and the deterioration of the life due to the stress of the switching element can be alleviated, and the life of the switching element due to discharge is adversely affected. Can be suppressed.

  FIG. 1 is a schematic configuration diagram of a vehicle system according to an embodiment of the present invention. As shown in FIG. 1, the vehicle system includes a battery 2, a booster 4, an inverter 6, a DCDC converter 8, an electric air conditioner 10, an electric oil pump 12, an electric power steering 14, an electric motor 16, a position detecting means 18, an engine 20, A management ECU 22, an engine ECU 24, a motor ECU 26, a battery ECU 28, and a booster ECU 30 are provided.

  The battery 2 is a power storage device for supplying electric power to the electric motor 16 via the booster 4 and the inverter 6, and is a lithium ion battery, a nickel hydrogen battery, or the like, and a plurality of battery blocks in which a plurality of single cells are modularized. Are connected in series. The battery 2 may be a capacitor.

  The booster 4 is a voltage converter (buck-boost converter) that performs voltage conversion modulation that modulates the battery voltage from the battery 2 to a predetermined boosted voltage. As shown in FIG. Side smoothing capacitor C0, reactors LX, LY, LZ, switching elements XH, YH, ZH, XL, YL, ZL, flywheel diode DXH, DYH, DZH, DXL, DYL, DZL, capacitors CXH, CYH, CZH, CXL, CYL, CZL, a high-voltage side smoothing capacitor C1 and a voltage sensor 52 are provided.

  The contactor 50 is configured by a relay having a 1a contact configuration that mechanically turns on / off the connection between the positive electrode of the battery 2 and the high side of the booster 4, and the contactor 50 on the side of the battery 2 that performs or cuts off the power supply to the booster. Connecting / disconnecting means, one contact is connected to the positive electrode of the battery 2, and the other contact is connected to the positive electrode of the smoothing capacitor C0 and one terminal of the reactors LX, LY, and LZ.

  The smoothing capacitor C <b> 0 is a capacitor that smoothes the voltage from the battery 2. The positive electrode is connected to the other contact of the contactor 50, and the negative electrode is connected to the negative electrode of the battery 2.

  The reactor LX is an X-phase reactor for step-up / step-down, one terminal is connected to the other contact of the contactor 50, the other terminal is the emitter of the switching element XH, the collector of the switching element XL, the flywheel diode DXH. , The cathode of the flywheel diode DXL, and one of the electrodes of the capacitors CXH and CXL.

  Reactor LY is a Y-phase reactor for step-up / step-down, one terminal is connected to the other contact of contactor 50, the other terminal is the emitter of switching element YH, the collector of switching element YL, flywheel diode DYH. Are connected to one of the electrodes of the capacitors CYH and CYL.

  Reactor LZ is a Z-phase reactor for step-up / step-down, one terminal is connected to the other contact of contactor 50, the other terminal is the emitter of switching element ZH, the collector of switching element ZL, flywheel diode DZH. Are connected to one of the anodes, the cathode of the flywheel diode DZL, and the capacitors CZH and CZL.

  The H-side switching element XH is, for example, an IGBT element, the emitter is connected to the other terminal of the reactor LX, and the collector is connected to the positive electrode of the smoothing capacitor C1. A gate signal is input from the booster ECU 30 to the gate. The H-side flywheel diode DXH is connected in antiparallel with the H-side IGBT element XH, the anode is connected to the emitter of the H-side IGBT element XH, and the cathode is connected to the collector of the H-side IGBT element XH. The H-side capacitor CXH is a capacitor for soft switching of the H-side IGBT element XH. One electrode is connected to the collector of the H-side IGBT element XH and the cathode of the H-side flywheel diode DXH, and the other electrode is H-side. It is connected to the emitter of the IGBT element XH and the anode of the H-side flywheel diode DXH.

  L-side IGBT element XL has a collector connected to the other terminal of reactor LX and an emitter connected to the negative electrode of battery 2. A gate signal is input from the booster ECU 30 to the gate. The L-side flywheel diode DXL is connected in antiparallel with the L-side IGBT element XL, the anode is connected to the emitter of the L-side IGBT element XL, and the cathode is connected to the collector of the L-side IGBT element XL. The L-side capacitor CXL is a capacitor for soft switching of the L-side IGBT element XL. One electrode is connected to the collector of the L-side IGBT element XL and the cathode of the L-side flywheel diode DXL, and the other electrode is on the L side. It is connected to the emitter of the IGBT element XL and the anode of the L-side flywheel diode DXL.

  The H-side IGBT element YH has an emitter connected to the other terminal of the reactor LY and a collector connected to the positive electrode of the smoothing capacitor C1. A gate signal is input from the booster ECU 30 to the gate. The H-side flywheel diode DYH is connected in antiparallel with the H-side IGBT element YH, the anode is connected to the emitter of the H-side IGBT element YH, and the cathode is connected to the collector of the H-side IGBT element YH. The H-side capacitor CYH is a capacitor for soft switching of the H-side IGBT element YH. One electrode is connected to the collector of the H-side IGBT element YH and the cathode of the H-side flywheel diode DYH, and the other electrode is H-side. It is connected to the emitter of the IGBT element YH and the anode of the H-side flywheel diode DYH.

  L-side IGBT element YL has a collector connected to the other terminal of reactor LY and an emitter connected to the negative electrode of battery 2. A gate signal is input from the booster ECU 30 to the gate. The L-side flywheel diode DYL is connected in antiparallel with the L-side IGBT element YL, the anode is connected to the emitter of the L-side IGBT element YL, and the cathode is connected to the collector of the L-side IGBT element YL. The L-side capacitor CYL is a capacitor for soft switching of the L-side IGBT element YL. One electrode is connected to the collector of the L-side IGBT element YL and the cathode of the L-side flywheel diode DYL, and the other electrode is on the L side. It is connected to the emitter of the IGBT element YL and the anode of the L-side flywheel diode DYL.

  The H-side IGBT element ZH has an emitter connected to the other terminal of the reactor LZ and a collector connected to the positive electrode of the smoothing capacitor C1. A gate signal is input from the booster ECU 30 to the gate. The H-side flywheel diode DZH is connected in antiparallel with the H-side IGBT element ZH, the anode is connected to the emitter of the H-side IGBT element ZH, and the cathode is connected to the collector of the H-side IGBT element ZH. The H-side capacitor CZH is a capacitor for soft switching of the H-side IGBT element ZH. One electrode is connected to the collector of the H-side IGBT element ZH and the cathode of the H-side flywheel diode DZH, and the other electrode is H-side. It is connected to the emitter of the IGBT element ZH and the anode of the H-side flywheel diode DZH.

  L-side IGBT element ZL has a collector connected to the other terminal of reactor LZ and an emitter connected to the negative electrode of battery 2. A gate signal is input from the booster ECU 30 to the gate. The L-side flywheel diode DZL is connected in antiparallel with the L-side IGBT element ZL, the anode is connected to the emitter of the L-side IGBT element ZL, and the cathode is connected to the collector of the L-side IGBT element ZL. The L-side capacitor CZL is a capacitor for soft switching of the L-side IGBT element ZL. One electrode is connected to the collector of the L-side IGBT element ZL and the cathode of the L-side flywheel diode DZL, and the other electrode is on the L side. It is connected to the emitter of the IGBT element ZL and the anode of the L-side flywheel diode DZL.

  Reactors LX, LY, LZ, etc. are in the X, Y, Z phase because the H-side IGBT elements XH, YH, ZH and L-side IGBT elements XL, YL, ZL are shifted by 120 ° at the time of step-up or step-down. This is because the ripple current is suppressed by turning ON / OFF.

  The smoothing capacitor C1 is a capacitor that smoothes the boosted voltage. The positive electrode is connected to the collectors of the H-side IGBT elements XH, YH, and ZH, and the negative electrode is connected to the negative electrode of the battery 2. The voltage sensor 52 is a sensor that detects the voltage across the smoothing capacitor C1, and outputs an electrical signal corresponding to the voltage, for example, an analog signal. The output signal of the voltage sensor 52 is input to the booster ECU 30.

  The inverter 6 is a connecting / disconnecting means on the side of the load 16 that implements or cuts off power supply from the booster 4 to the electric motor 16 (load). The boosted voltage boosted by the booster 4 is turned on by the motor ECU 26 to turn on an IGBT element (not shown). Is converted into a three-phase AC voltage by PWM control of / OFF and output to the motor 16, and the three-phase AC voltage from the motor 16 is converted into a DC voltage by full-wave rectification by turning off all IGBT elements (not shown) under the control of the motor ECU 26. Convert to

  When the smoothing capacitor C1 of the booster 4 to be described later is discharged, the IGBT elements of the inverter 6 are all turned off by the control of the motor ECU 26, and undesired torque supply from the smoothing capacitor C1 to the electric motor 16 is prevented.

  DCDC converter 8 steps down the voltage from battery 2 and charges the auxiliary battery. The electric air conditioner 10 drives the air conditioner based on the voltage from the battery 2. The electric oil pump 12 drives the oil pump based on the voltage from the battery 2. The electric power steering 14 drives the steering based on the voltage from the battery 2.

  The electric motor 16 is connected to the engine 20. The position detection means 18 is a sensor that detects the relative rotation angle between the stator and the rotor of the electric motor 16, and outputs an electrical signal (position signal) corresponding to the relative rotation angle, for example, an analog signal. The engine 20 is, for example, a 4-cycle DOHC type spark ignition gasoline internal combustion engine.

  The management ECU 22 issues an engine start permission / output command to the engine ECU 24 from the engine state output from the engine ECU 24, calculates the motor torque from the engine state and the motor state output from the motor ECU 26, and outputs the torque command to the motor ECU 26. To do. Further, based on the engine state and the remaining capacity SOC of the battery 2 from the battery ECU 28, the motor ECU 26 is instructed to perform regenerative control.

  Based on the motor torque command from the management ECU 22, the motor ECU 26 outputs a gate signal to the inverter 6 by the PWM modulation method to convert the DC voltage from the booster 4 to AC when driving the motor 16, and regenerates it. In some cases, a gate signal is output to the inverter 6 in order to convert the three-phase AC voltage output from the electric motor 16 into a DC voltage by full-wave rectification. Further, when the smoothing capacitor C1 of the booster 4 is discharged, all the IGBT elements of the inverter 6 are turned off. The battery ECU 28 calculates the remaining capacity (SOC) from the voltage, current, and temperature of the battery 2 and outputs the remaining capacity (SOC) to the management ECU 22.

  The booster ECU 30 controls the boost operation, the step-down operation, and the discharge of the smoothing capacitor C1 by the booster 4.

(1) Boosting operation At the time of boosting, the L-side IGBT elements XL, YL, ZL are turned ON / OFF at a duty ratio corresponding to the boosting ratio based on the carrier frequency. On the other hand, the H-side IGBT elements XH, YH, and ZH are complementary to the L-side IGBT elements XL, YL, and ZL (OFF when the H-side IGBT element is ON), and ON / Turn off. The dead time is a time during which the L side and H side IGBT elements XH and XL, YH and YL, and ZH and ZL are simultaneously turned OFF. The reason for providing the dead time is to sufficiently charge and discharge the capacitors CXH, CXL, CYH, CYL, CZH, and CZL in the meantime to realize ZVRT (Zero-Voltage Resonant Transition) and reduce the switching loss. For example, when XL is turned on after the dead time, when the boost operation is performed in the discontinuous conduction mode, the L-side flywheel diode DXL is turned on at the start of the dead time, the capacitor CXL is discharged, and the capacitor CXL is started to be charged. When the capacitor CXL finishes discharging in the dead time and then turns on the L-side IGBT element XL, the L-side IGBT element XL is turned on by 0 V, and the switching loss of the L-side IGBT element XL is reduced.

(2) Step-down operation At the time of step-down, the H-side IGBT elements XH, YH, ZH are turned ON / OFF at a duty ratio corresponding to the step-down ratio based on the carrier frequency. On the other hand, the L-side IGBT elements XL, YL, ZL are turned ON / OFF so as to be complementary to the H-side IGBT elements XH, YH, ZH and to provide a fixed dead time. The dead time is provided as in the case of boosting. For example, when the H-side IGBT element XH is turned on after the dead time, when the step-down operation is performed in the discontinuous conduction mode, the H-side flywheel diode DXH is turned on at the start of the dead time, the capacitor CXH is discharged, and the capacitor CXL is turned on. When charging is started and the capacitor CXH finishes discharging in dead time, and then the H-side IGBT element XH is turned on, the H-side IGBT element XH is turned on by 0 V, and the switching loss of the H-side IGBT element XH is reduced.

(3) Discharge Operation FIG. 3 is a functional block diagram of the booster ECU 30 related to the discharge operation of the smoothing capacitor C1 according to the present invention. The discharge start determination means 100, the discharge start control means 102, the discharge pattern calculation means 104, the gate signal An output unit 106 and a discharge end determination unit 108 are provided. The discharge start determination unit 100 determines whether or not the discharge of the smoothing capacitor C1 is started. As for the start of discharge, for example, it is assumed that a discharge command is issued when the ignition switch is turned on. The discharge start control means 102 turns off the contactor 50 and cuts off the connection between the battery 2 and the booster 4 when the discharge start determination means 100 determines that the discharge is started. Further, all the IGBT elements constituting the inverter 6 are turned off through the motor ECU 32 to cut off the power supply from the booster 4.

  The discharge pattern calculation means 104 uses a discharge pattern for sequentially switching ON / OFF of the IGBT elements XH, XL, YH, YL, ZH, and ZL based on the carrier frequency in order to discharge the electric charge of the smoothing capacitor C1. Calculate based on

  (1) Do not short-circuit the H-side IGBT elements XH, YH, ZH and the L-side IGBT elements XL, YL, ZL. This is because a large current flows due to a short circuit, resulting in an increase in switching loss and conduction loss, and deterioration of the IGBT elements XH, XL, YH, YL, ZH, and ZL increases. That is, the H-side IGBT element XH and the L-side IGBT element XL, the H-side IGBT element YH and the L-side IGBT element YL, and the H-side IGBT element ZH and the L-side IGBT element ZL are not simultaneously turned on. Therefore, when the H-side IGBT elements XH, YH, ZH are turned on, the L-side IGBT element having a phase different from that of the turned-on H-side IGBT element is turned on, so that the smoothing capacitor C1, H-side IGBT element, reactor on the discharge path is turned on. And the closed circuit by the L side IGBT element is formed. For example, when the H-side IGBT element XH and the L-side IGBT element YL are turned ON, the smoothing capacitor C1 → H-side IGBT element XH → reactor LX → reactor LY → L-side IGBT element YL constitutes a closed circuit, and the discharge current is Flowing. Therefore, the reactors LX, LY, and LZ consume the energy of the smoothing capacitor C1, so that the inrush current is suppressed, and the heat generation and stress of parts such as the IGBT elements XH, YH, ZH, XZ, YL, and ZL are reduced, and the lifetime Impact is reduced. The magnetic energy accumulated in the reactors LX, LY, LZ is released into the atmosphere.

  FIG. 4 is a diagram showing a combination of H-side IGBT elements XH, YH, ZH and L-side IGBT elements XL, YL, ZL being ON. White circles indicate that they can be turned ON, and H-side IGBT elements XH and L-side IGBT element XL, H-side IGBT element YH and L-side IGBT element YL, H-side IGBT element ZH and L-side IGBT element ZL must not be turned on at the same time, but other ON combinations are possible.

  (2) Prior to turning on the H-side IGBT elements XH, YH, and ZH, one of the L-side IGBT elements XL, YL, and ZL is already turned on. For example, the L-side IGBT element YL or ZL is turned on before the H-side IGBT element XH is turned on. When the H-side IGBT element XH is turned on and the L-side IGBT elements YL and ZL are turned off, a series LC circuit is formed by the reactor LX and the smoothing capacitor C0 using the smoothing capacitor C1 as a DC power source. Since the voltage and current of the smoothing capacitor C0 are excessive (may be higher than the voltage of the smoothing capacitor C1), a high voltage is applied to the smoothing capacitor C0 and the contactor 50, and it is necessary to increase the component breakdown voltage on the battery 2 side. There is. Further, if there is no smoothing capacitor C0, the high voltage of the smoothing capacitor C0 needs to be directly applied to the components on the battery 2 side, such as the contactor 50, and the component breakdown voltage on the battery 2 side must be increased. However, by turning on the L-side IGBT element YL or ZL before turning on the H-side IGBT element XH, when the IGBT element XH is turned on, the reactor LX, the smoothing capacitor C0 and the reactor LY or A series circuit of the parallel circuit of LZ and the reactor LX is formed, and the voltage rise of the smoothing capacitor C0 is suppressed in the transient phenomenon. Thereby, since a high voltage is not applied to the components on the battery 2 side, it can be configured without increasing the component withstand voltage on the battery 2 side, resulting in low loss, small size, and low cost.

  (3) The discharge completion time until the charge of the smoothing capacitor C1 is completely discharged is shortened. The discharge end time is determined by a discharge time and a discharge current in which both the H-side IGBT element and the L-side IGBT element are turned on and a discharge current flows. When a plurality of (two) H-side IGBT elements are simultaneously turned on, the discharge current is composed of a plurality of reactors to which a plurality of reactors connected to the H-side IGBT elements are connected, and the inductance of the combined reactor Becomes 1/2, and the discharge current increases. When a plurality (two) of the L-side IGBT elements are turned ON simultaneously, a parallel circuit is formed by the plurality of reactors connected to the L-side IGBT elements, and the inductance of the combined reactor becomes 1/2, and the discharge current is reduced. growing.

  (4) The IGBT elements XH, YH, ZH, XL, YL, and ZL are deteriorated when heat is generated by switching. Therefore, the amount of heat generated in the IGBT element is equalized, the influence on components such as the IGBT element is equalized, heat generation is dispersed, and the lifetime of the IGBT element is equalized.

  (5) A dead time is provided to realize ZVRT of the IGBT elements XH, YH, ZH, XL, YL, and ZL, thereby reducing the switching loss of the IGBT elements and suppressing the deterioration of the IGBT elements.

  The gate signal output means 106 outputs a gate signal based on the discharge pattern, and sequentially switches the IGBT elements XH, YH, ZH, XL, YL, and ZL to be turned on / off to control energization. The discharge end determination means 108 determines whether or not the discharge of the smoothing capacitor C1 has ended. The end of the discharge may be detected by calculating a discharge end time from the discharge time and discharge current based on the discharge pattern, and may be detected by a timer, or may be detected when the voltage detected by the voltage sensor 52 becomes 0V.

First Embodiment FIG. 4 is a flowchart showing a discharge method according to an embodiment of the present invention. FIG. 5 is a view showing a discharge pattern according to the first embodiment of the present invention. Hereinafter, the discharge method will be described with reference to the drawings. In step S2, it is determined whether or not a discharge command, for example, an ignition switch has been turned OFF. If a positive determination is made, the process proceeds to step S4. If a negative determination is made, the process ends. In step S4, the contactor 50 is turned off and all the IGBT elements of the inverter 6 are turned off. In step S6, the discharge pattern shown in FIG. 6 is generated based on the carrier frequency.

  The discharge pattern in FIG. 6 is based on shortening the discharge time. First, when the H-side IGBT elements XH, YH, and ZH are turned on, the L-side IGBT elements are already turned on. For example, when the H-side IGBT element XH is turned on at times t1 and t10, an L-side IGBT element different from the X phase, for example, the L-side IGBT element YL is turned on at times t0 and t9 prior to times t1 and t10. Yes.

  Further, when one H-side IGBT element and a plurality of L-side IGBT elements, for example, the H-side IGBT element XH is ON during times t1 to t2 and t10 to t11, the L-side IGBT elements YL and L side ZL is ON. Thereby, as shown in FIG. 7, the discharge current flows through the path a1 of the smoothing capacitor C1 → the H-side IGBT element XH → the reactor LX, and the reactor LY → the L-side IGBT element YL shown in the path a2 and the reactor shown in the path a3. LZ → Branch by L side IGBT element ZL, and closed circuit is constituted by smoothing capacitor C1, H side IGBT element XH, reactors LX, LY, LZ, L side IGBT elements YL, ZL on these paths a1, a2, a3 Is done. As a result, a parallel circuit of reactors LY and LZ is formed, the inductance of the combined reactor is halved, and the discharge current is larger than in the case of only reactor LY or only LZ.

  Similarly, as shown in FIG. 8, when the H-side IGBT element YH is ON during the times t4 to t5 and t13 to t14, since the L-side IGBT elements XL and ZL are ON, the discharge current is The closed circuit is constituted by the smoothing capacitor C1, the H-side IGBT element YH, the reactors LY, LX, LZ, and the L-side IGBT elements XL, ZL on the paths b1, b2, b3. Also, as shown in FIG. 9, when the H-side IGBT element ZH is ON during the times t7 to t8 and t16 to t17, the L-side IGBT elements XL and YL are ON, so that the discharge current is routed. The closed circuit is constituted by the smoothing capacitor C1, the H-side IGBT element ZH, the reactors LZ, LX, LY, and the L-side IGBT elements XL, YL on the paths c1, c2, c3.

  Furthermore, in order to realize ZVRT, dead times are provided at times t0 to t1, t2 to t3, t4 to t5, t5 to t6, t6 to t7, t8 to t9, and the like.

  In step S8 in FIG. 5, a gate signal for turning ON / OFF the IGBT elements XH, YH, ZH, XL, YL, and ZL is output based on the discharge pattern. The smoothing capacitor C1 is discharged. The smoothing capacitor C0 discharges according to the discharge of the smoothing capacitor C1. In step S10, it is determined whether or not the discharge is completed depending on whether or not the voltage value across the smoothing capacitor C1 output from the voltage sensor 52 is 0V. If a positive determination is made, the process ends. If the determination is negative, the process returns to step S6 to generate the discharge pattern shown in FIG.

  According to the first embodiment described above, since the plurality of L-side IGBT elements are simultaneously turned on when the H-side IGBT is turned on, the discharge current increases and the discharge end time can be shortened.

  In the discharge pattern of FIG. 6, even when the X-, Y-, and Z-phase H-side IGBT elements XH, YH, and ZH are OFF, the return current flows from the flywheel diodes DXL, DYL, and DZL, and the step-down operation is performed. The step-down voltage is supplied to the DCDC converter 8 and the auxiliary battery can be charged. As a result, the discharge end time is shortened and the charge of the capacitor C1 can be used effectively. Moreover, since ZVRT is realized, switching loss can be reduced and deterioration of the IGBT element can be suppressed.

  A plurality of H-side IGBT elements XH, YH, ZH are simultaneously turned on, only one L-side IGBT element XL, YL, ZL is turned on, and a reactor to which the plurality of turned-on H-side IGBT elements are connected is connected in parallel. Then, the inductance of the combined reactor may be halved to increase the discharge current.

Second Embodiment FIG. 10 is a diagram showing a discharge pattern according to a second embodiment of the present invention. The discharge pattern in FIG. 10 is based on stress equalization. First, when the H-side IGBT elements XH, YH, and ZH are turned on, the L-side IGBT element is already turned on and a dead time is provided, as in the first embodiment.

  In the present embodiment, the number of IGBT elements that are simultaneously turned on is one for each of the H-side IGBT elements XH, YH, ZH and the L-side IGBT elements XL, YL, ZL. Also, in one carrier cycle, the time during which current flows through the H-side IGBT elements XH, YH, ZH and the L-side IGBT elements XL, YL, ZL is the same.

  In this case, the combination in which the H side IGBT element and the L side IGBT element can be simultaneously turned on is the H side IGBT element XH, the L side IGBT element YL is ON, the H side IGBT element XH, the L side IGBT element ZL is ON, and the H side IGBT element YH. , L-side IGBT element XL is ON, H-side IGBT element YH, L-side IGBT element ZL is ON, H-side IGBT element ZH, L-side IGBT element XL is ON, H-side IGBT element ZH, L-side IGBT element YL is ON This is the case.

  Among these combinations, in the discharge pattern shown in FIG. 10, the H-side IGBT element XH and the L-side YL are simultaneously turned on, and the smoothing capacitor C1 → H-side IGBT element XH → reactor LX path as shown in FIG. A closed circuit is configured by d1 and the smoothing capacitor C1, the H-side IGBT element XH, the reactors LX, LY, and the L-side IGBT element YL on the path d2 of the reactor LY → L-side IGBT element YL.

  In the discharge pattern shown in FIG. 10, the H-side IGBT element YH and the L-side IGBT element ZL are simultaneously turned ON, and as shown in FIG. 12, the smoothing capacitor C1 → H-side IGBT element YH → reactor LZ path e1 and reactor. The smoothing capacitor C1, the H-side IGBT element YH, the reactors LY, LZ, and the L-side IGBT element ZL on the path e2 of the LZ → L-side IGBT element ZL constitute a closed circuit.

  Further, in the discharge pattern shown in FIG. 10, the H-side IGBT element ZH and the L-side IGBT element XL are simultaneously turned ON, and as shown in FIG. 13, the smoothing capacitor C1 → H-side IGBT element ZH → reactor LZ path f1 and reactor. The smoothing capacitor C1, the H-side IGBT element ZH, the reactors LZ, LX, and the L-side IGBT element XL on the path f2 of the LX → L-side IGBT element XL constitute a closed circuit.

  At this time, since the paths d1, d2, e1, e2, f1, and f2 do not branch, each closed circuit is composed of a series circuit of two reactors, and the discharge current flows through the IGBT elements XH, YH, ZH, XL, YL, and ZL. Are substantially equal.

  Further, as shown in FIG. 10, the discharge times t1 to t2 and t9 to t10 that flow when the H-side IGBT element XH and L-side IGBT element YL are turned ON, the H-side IGBT element YH and L-side IGBT element ZL are turned ON. The discharge times t4 to t5 and t13 to t14 flowing, the discharge times t7 to t8 and t16 to t17 flowing when the H-side IGBT element ZH and the L-side IGBT element XL are turned on are equal, and the discharge time in one carrier cycle Is the same for all IGBT elements XH, XL, YH, YL, ZY, ZL.

  As described above, since the discharge time and the discharge current are substantially equal in the IGBT elements XH, YH, ZH, XL, YL, and ZLw, the loads of the IGBT elements XH, XL, YH, YL, ZY, and ZL can be equalized. In addition, since the discharge current is small compared to the first embodiment, the stress on the IGBT elements XH, XL, YH, YL, ZY, ZL can be reduced. For this reason, it is possible to expect a longer life of the parts.

Third Embodiment FIG. 14 is a block diagram of a booster according to a third embodiment to which the present invention is applicable. Components that are substantially the same as those in FIG. 2 are given the same reference numerals. . In the present embodiment, reactors LX and LY, IGBT elements XH, XL, YH, and YL and flywheel diodes DXH, DXL, DYH, and DYL are provided for the X phase and the Y phase. Flywheel diodes DXH, DXL, DYH, and DYL are connected in reverse parallel to IGBT elements XH, XL, YH, and YL.

  In the booster shown in FIG. 14, the discharge pattern for discharging the charge of the smoothing capacitor C1 is to turn on the IGBT elements XH and YL, and the path from the smoothing capacitor C1 to the H-side IGBT element XH to the reactor LX shown in FIG. A closed circuit is configured by the smoothing capacitor C1, the H-side IGBT element XH, the reactors LX, LY, and the L-side IGBT element YL on the path g2 of g1 and the reactor LY → L-side IGBT element YL. Further, the H-side IGBT element YH and the L-side IGBT element XL are turned ON, and the smoothing capacitor C1 → H-side IGBT element YH → reactor LY path h1 and the reactor LX → L-side IGBT element XL path h2 shown in FIG. The smoothing capacitor C1, the H-side IGBT element YH, the reactors LY and LX, and the L-side IGBT element XL constitute a closed circuit. Also in this discharge pattern, the L-side IGBT elements YL and XL are turned on before the H-side IGBT elements XH and YH are turned on. The effect of this embodiment is the same as that of the second embodiment.

  In FIG. 2, in the case of a booster that does not have a Y-phase and a Z-phase and has one reactor, an H-side IGBT element and an L-side IGBT element are provided for discharging, and the collector of the H-side IGBT element. Is connected to the positive electrode of the smoothing capacitor C1, the emitter is connected to the reactor terminal on the smoothing capacitor C1 side, the collector of the L-side IGBT element is connected to the reactor terminal on the battery 2 side, and the emitter is connected to the negative electrode of the battery 2 Then, a discharge pattern similar to that in the second embodiment may be generated.

1 is a schematic configuration diagram of a vehicle system to which the present invention is applied. It is a figure which shows an example of the booster in FIG. 3 is a functional block diagram of a booster ECU according to the present invention. FIG. 3 is a flowchart illustrating a discharge method according to an embodiment of the present invention. It is a figure which shows the combination of ON of the H side and L side IGBT element. It is a figure which shows the discharge pattern by 1st Embodiment of this invention. It is a figure which shows the closed circuit by 1st Embodiment of this invention. It is a figure which shows the closed circuit by 1st Embodiment of this invention. It is a figure which shows the closed circuit by 1st Embodiment of this invention. It is a figure which shows the discharge pattern by 2nd Embodiment of this invention. It is a figure which shows the closed circuit by 2nd Embodiment of this invention. It is a figure which shows the closed circuit by 2nd Embodiment of this invention. It is a figure which shows the closed circuit by 2nd Embodiment of this invention. It is a figure which shows the booster by 3rd Embodiment of this invention. It is a figure which shows the closed circuit by 3rd Embodiment of this invention. It is a figure which shows the closed circuit by 3rd Embodiment of this invention.

Explanation of symbols

2 DC power supply 4 Booster 6 Inverter 16 Motor 30 Booster ECU
50 Contactor 52 Voltage sensor C0, C1 Smoothing capacitor

Claims (6)

A control device comprising: a power supply; a load; a voltage conversion circuit that converts an amplitude of a voltage of the power supply; and a connection / disconnection means on the power supply side that implements or cuts off power supply from the power supply to the voltage conversion circuit. And
The voltage conversion circuit includes a plurality of switching elements and a plurality of reactors, and a smoothing capacitor connected in parallel to the load,
A first closed circuit is configured by turning on the switching element from the smoothing capacitor, the plurality of switching elements, and one or more of the reactors,
A second closed circuit different from the first closed circuit is configured by turning on the switching element from the smoothing capacitor, the plurality of switching elements and one or more reactors,
When the power supply from the power supply to the voltage conversion circuit is cut off by the power supply side connection / disconnection means, the first closed circuit and the second closed circuit are sequentially changed by the on / off operation of the switching element. Energized ,
The voltage conversion circuit includes a plurality of switching elements on each of a high potential side and a low potential side when viewed from each reactor, and the switching elements on the low potential side when viewed from the reactor are connected to the high potential side. By turning on prior to each switching element, the first and second closed circuits are configured,
A control apparatus comprising: turning off the switching element on the low potential side after turning off the switching element on the high potential side .   The voltage conversion circuit further includes connection / disconnection means on the load side that implements or cuts off power supply from the voltage conversion circuit to the load, and the power supply side connection / disconnection means and the load-side connection / disconnection means The first closed circuit and the second closed circuit are sequentially changed and energized when an ON / OFF operation of each of the switching elements is performed when power supply to the load is interrupted. The control device according to 1.   The voltage conversion circuit is provided with a plurality of the switching elements on each of a high potential side and a low potential side when viewed from each reactor, and the switching element on either the high potential side or the low potential side The control device according to claim 1, wherein the first and second closed circuits are configured by simultaneously turning on a plurality of switches and turning on one or more of the switching elements on the other side. The switching device control device according to any one of claims 1 to 3, characterized in that to the on-off operation at every predetermined time.   3. The control apparatus according to claim 2, wherein the load side connecting / disconnecting means is an inverter, and the load is an electric motor. The first and second closed circuits include diodes connected in parallel to the respective switching elements, and the voltage conversion circuit boosts the voltage of the power supply and supplies the boosted voltage to the load side. control device according to any one of claims 1 to 5 which is a boost converter.

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