JP2006246653A - Voltage converter system, motor drive unit, and control method of voltage converter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a voltage converter system which protects an overvoltage generated at a low voltage side of a voltage converter when the voltage converter starts a voltage-fall operation from an operation suspended state. <P>SOLUTION: In the voltage converter system, when a predetermined malfunction is caused, a controller 30 suspends an operation of a voltage-rise converter 10 (S20). When a malfunction state is dissolved (YES in S40), the controller 30 verifies whether a voltage VH at a high-voltage side (a side of an inverter 20) of the voltage-rise converter 10 is lower than a breakdown voltage of components for equipment connected to the low voltage side (a B side of a battery) of the voltage-rise converter 10 (S60), then after the voltage VH becomes lower than the breakdown voltage of the components, suspension of the operation of the voltage-rise converter 10 is released (S70). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a voltage conversion device, a motor drive device, and a voltage converter control method, and in particular, a voltage conversion device, a motor drive device, and a device capable of protecting a device connected to a low voltage side of the voltage converter from an overvoltage. The present invention relates to a method for controlling a voltage converter.

  Japanese Patent Application Laid-Open No. 2004-274945 (Patent Document 1) prevents an overvoltage from being applied to a device connected to a primary side (DC power supply side) of a voltage converter that performs voltage conversion when a DC power supply fails. Disclose motor drive measures. This motor drive device includes a DC power supply, a boost converter, inverters IA and IB, a DC / DC converter, a system relay, and a control device. The boost converter is connected to a DC power supply via a system relay. Inverters IA and IB are connected in parallel to the boost converter and drive AC motors MA and MB, respectively. The DC / DC converter is connected between the system relay and the boost converter.

In this motor drive device, when the control device detects a failure of the DC power supply, it controls inverters IA and IB so that AC motors MA and MB output zero output torque. And a control device outputs the signal which instruct | indicates interruption | blocking of a system relay to a system relay, and interrupts | blocks a system relay. Thereafter, the control device switches control of the boost converter to step-down control. According to this motor drive device, it is possible to prevent an overvoltage from being applied to the DC / DC converter connected to the primary side (DC power supply side) of the boost converter. (See Patent Document 1).
JP 2004-274945 A JP 2003-244801 A Japanese Patent Laid-Open No. 11-41705

  When an abnormality that may cause malfunction or damage of the boost converter occurs, the control device generally stops the operation of the boost converter and holds data in the control device. When returning from the abnormal state, the control device starts the operation of the boost converter, releases the data hold, and starts control of the boost converter based on data newly taken in from the outside.

  Here, because the control device operates in a predetermined control cycle, the voltage conversion rate (step-up rate or step-down rate) held in the abnormal state for one control cycle immediately after the start of the operation of the boost converter is used. Controls the boost converter. If the voltage on the secondary side (inverter side) of the boost converter rises due to the regenerative operation of the motor during the abnormal state, there is a possibility that an overvoltage is supplied from the secondary side of the boost converter to the primary side.

  For example, it is assumed that an abnormal state occurs when the step-down rate of the boost converter is R, and the secondary side voltage of the boost converter increases during the abnormal state. At this time, immediately after the operation of the boost converter is started, the control device starts control of the boost converter with the step-down rate as R, so that a voltage obtained by stepping down the increased secondary voltage with the step-down rate R is supplied to the primary side. End up. If this supply voltage exceeds the component breakdown voltage of a device (such as a DC / DC converter) connected to the primary side of the boost converter, the device is damaged.

  Japanese Patent Application Laid-Open No. 2004-274945 described above does not disclose the problem of overvoltage that may occur immediately after the start of the operation of such a boost converter, and means for solving it. Such a problem cannot be solved by the technique disclosed in Japanese Patent Application Laid-Open No. 2004-274945 described above.

  Accordingly, the present invention has been made to solve such a problem, and an object of the present invention is to provide an overvoltage that can be generated on the low voltage side of the voltage converter when the voltage converter starts a step-down operation from the operation stop state. It is an object of the present invention to provide a voltage conversion device that prevents the above.

  Another object of the present invention is to provide a motor drive device that prevents an overvoltage that may occur on the low voltage side of the voltage converter when the voltage converter starts a step-down operation from an operation stop state.

  Furthermore, another object of the present invention is to provide a voltage converter control method for preventing an overvoltage that may occur on the low voltage side of the voltage converter when the voltage converter starts a step-down operation from an operation stop state. It is.

  According to the present invention, the voltage converter outputs a voltage converter that steps down the DC voltage and supplies the voltage to the electric load, and a command that instructs the voltage converter to stop when a predetermined abnormality occurs. And a controller that cancels the command when it is confirmed that the DC voltage is lower than the predetermined voltage level after the predetermined abnormality is resolved.

  In the voltage converter according to the present invention, when the step-down operation of the voltage converter is started after the predetermined abnormality is resolved, whether or not the DC voltage before the step-down (the high voltage side of the voltage converter) is lower than the predetermined voltage level. Is confirmed. Then, when it is confirmed that the DC voltage is lower than a predetermined voltage level, the command for stopping the voltage converter that has been output to the voltage converter is canceled. Thus, when the voltage converter starts a step-down operation, a voltage higher than a predetermined voltage level is not supplied to the electric load that receives the step-down voltage from the voltage converter.

  Therefore, according to the voltage converter of the present invention, it is possible to prevent an overvoltage from being applied to the electric load that receives the step-down voltage from the voltage converter by setting the predetermined voltage level to an appropriate value.

  Preferably, the predetermined voltage level is determined based on a component breakdown voltage of the electric load.

  In this voltage converter, the predetermined voltage level is determined based on the component withstand voltage of the electric load that receives the step-down voltage from the voltage converter, so when the voltage converter starts the step-down operation, the component is applied to the electric load. No voltage exceeding the withstand voltage is supplied.

  Therefore, according to this voltage converter, it is possible to prevent an overvoltage exceeding the component breakdown voltage from being applied to the electric load that receives the step-down voltage from the voltage converter.

  Preferably, the voltage conversion device further includes a discharge circuit that reduces the DC voltage when the DC voltage is equal to or higher than a predetermined voltage level after the predetermined abnormality is resolved.

  In this voltage converter, when the DC voltage before stepping down (on the high voltage side of the voltage converter) is equal to or higher than a predetermined voltage level after the predetermined abnormality is resolved, the DC voltage before stepping down is reduced by the discharge circuit. As a result, the DC voltage before stepping down can be supplied to the electric load after being lowered below the component withstand voltage of the electric load receiving the stepped-down voltage from the voltage converter.

  Therefore, according to this voltage converter, the electric load that receives the step-down voltage from the voltage converter can be reliably protected from overvoltage.

  According to the invention, the motor drive device includes a DC power supply, a drive device that drives the motor, a voltage converter that steps down a DC voltage from the drive device and supplies the voltage to the DC power supply side, a DC power supply, and a voltage. When a predetermined abnormality occurs with the electrical load connected to the converter, a command to stop the voltage converter is output to the voltage converter, and the DC voltage from the drive device is resolved after the predetermined abnormality is resolved. And a control device that cancels the command when it is confirmed that the voltage is lower than a predetermined voltage level.

  In the motor drive device according to the present invention, when the step-down operation of the voltage converter is started after the predetermined abnormality is eliminated during the regenerative operation of the motor, the DC voltage on the high voltage side (drive device side) of the voltage converter is predetermined. It is confirmed whether it is lower than the voltage level. Then, when it is confirmed that the DC voltage is lower than a predetermined voltage level, the command for stopping the voltage converter that has been output to the voltage converter is canceled. Thereby, when the voltage converter starts a step-down operation, a voltage higher than a predetermined voltage level is not supplied to the electric load connected to the low voltage side (DC power supply side) of the voltage converter.

  Therefore, according to the motor drive device of the present invention, an overvoltage is applied to the electric load connected to the low voltage side (DC power supply side) of the voltage converter by setting the predetermined voltage level to an appropriate value. Can be prevented.

  Preferably, the predetermined voltage level is determined based on a component breakdown voltage of the electric load.

  In this motor drive device, the predetermined voltage level is determined based on the component withstand voltage of the electric load. Therefore, when the voltage converter starts a step-down operation, the voltage converter has a low voltage side (DC power supply side). A voltage exceeding the component breakdown voltage is not supplied to the connected electrical load.

  Therefore, according to this motor drive device, it is possible to prevent an overvoltage exceeding the component breakdown voltage from being applied to the electric load connected to the low voltage side (DC power supply side) of the voltage converter.

  Preferably, the motor drive device further includes a discharge circuit connected between the drive device and the voltage converter.

  In this motor drive device, when the DC voltage on the high voltage side (drive device side) of the voltage converter is equal to or higher than a predetermined voltage level after the predetermined abnormality is eliminated, the DC voltage is lowered by the discharge circuit. As a result, the DC voltage on the high voltage side (drive device side) of the voltage converter is reduced below the component withstand voltage of the electric load connected to the low voltage side (power supply device side) of the voltage converter, and then to the electric load. Can be supplied.

  Therefore, according to this motor drive device, the electric load connected to the low voltage side (power supply device side) of the voltage converter can be reliably protected from overvoltage.

  Preferably, the voltage converter further has a boosting function of boosting a DC voltage from a DC power supply and supplying the boosted voltage to the driving device.

  According to the present invention, the voltage converter control method is a voltage converter control method for stepping down a DC voltage and supplying the voltage to an electric load. When a predetermined abnormality occurs, the voltage converter is stopped. The first step of outputting a command instructing the voltage converter to the voltage converter, the second step of determining whether or not the predetermined abnormality has been resolved, and the second step are determined to have resolved the predetermined abnormality A third step for determining whether or not the DC voltage is lower than a predetermined voltage level, and a third step for canceling the command when it is determined in the third step that the DC voltage is lower than the predetermined voltage level. 4 steps.

  In the voltage converter control method according to the present invention, when it is determined in the second step that the predetermined abnormality has been resolved, the DC voltage before stepping down (on the high voltage side of the voltage converter) is lower than the predetermined voltage level. Whether it is low or not is determined in the third step. When it is determined that the DC voltage before step-down is lower than the predetermined voltage level, in the fourth step, the command for instructing the stop of the voltage converter that has been output to the voltage converter is canceled. Thus, when the voltage converter starts a step-down operation, a voltage higher than a predetermined voltage level is not supplied to the electric load that receives the step-down voltage from the voltage converter.

  Therefore, according to the voltage converter control method of the present invention, it is possible to prevent an overvoltage from being applied to the electric load that receives the stepped-down voltage from the voltage converter by setting the predetermined voltage level to an appropriate value.

  Preferably, the predetermined voltage level is determined based on a component breakdown voltage of the electric load.

  In this voltage converter control method, the predetermined voltage level is determined based on the component withstand voltage of the electric load that receives the step-down voltage from the voltage converter, so when the voltage converter starts the step-down operation, the electric load No voltage exceeding the component breakdown voltage is supplied.

  Therefore, according to this voltage converter control method, it is possible to prevent an overvoltage exceeding the component withstand voltage from being applied to the electric load that receives the step-down voltage from the voltage converter.

  According to the present invention, when the step-down operation of the voltage converter is started after the predetermined abnormality is resolved, the direct-current voltage before step-down (the high voltage side of the voltage converter) is referred to, and the DC voltage before step-down is the predetermined voltage. After confirming that the level is lower than the level (such as the component withstand voltage of the electrical load connected to the low voltage side of the voltage converter), cancel the command that instructs the voltage converter to stop. Since it did in this way, it can prevent that an overvoltage is applied to the electric load which receives a step-down voltage from a voltage converter.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic block diagram of a motor drive device according to an embodiment of the present invention. Referring to FIG. 1, this motor drive device 100 includes a battery B, a boost converter 10, an inverter 20, a control device 30, a DC / DC converter 40, an auxiliary battery 50, a resistance element 60, System relay SR, capacitors C1, C2, voltage sensors 72, 74, 76, power supply lines PL1, PL2, and ground line SL are provided.

  Motor generator MG driven by motor drive device 100 is an AC motor, and is composed of, for example, a three-phase AC synchronous motor generator. Motor generator MG generates driving torque by the three-phase AC voltage received from inverter 20. Motor generator MG generates a three-phase AC voltage and outputs it to inverter 20 during the regenerative operation.

  The battery B, which is a direct current power source, is a chargeable / dischargeable battery, for example, a secondary battery such as nickel metal hydride or lithium ion. Battery B outputs the generated DC voltage to power supply line PL1. Battery B is generated by motor generator MG, and is charged with a DC voltage stepped down by boost converter 10 after rectification by inverter 20.

  Boost converter 10 includes a reactor L, power transistors Q1 and Q2, and diodes D1 and D2. Reactor L has one end connected to power supply line PL1, and the other end connected to the connection point of power transistors Q1 and Q2. Power transistors Q1 and Q2 are made of, for example, an IGBT (Insulated Gate Bipolar Transistor). Power transistors Q1, Q2 are connected in series between power supply line PL2 and ground line SL, and receive a signal PWC from control device 30 as a base. Diodes D1 and D2 are connected between the collectors and emitters of the power transistors Q1 and Q2, respectively, so that current flows from the emitter side to the collector side.

  Inverter 20 includes a U-phase arm 22, a V-phase arm 24 and a W-phase arm 26. U-phase arm 22, V-phase arm 24, and W-phase arm 26 are connected in parallel between power supply line PL2 and ground line SL. U-phase arm 22 includes power transistors Q3 and Q4 connected in series, V-phase arm 24 includes power transistors Q5 and Q6 connected in series, and W-phase arm 26 includes power transistors connected in series. It consists of transistors Q7 and Q8. Each power transistor Q3-Q8 is made of, for example, an IGBT. Between the collector and the emitter of each of the power transistors Q3 to Q8, diodes D3 to D8 that flow current from the emitter side to the collector side are respectively connected. A connection point of each power transistor in each phase arm is connected to a coil end opposite to the neutral point of each phase coil of motor generator MG.

  System relay SR is connected between battery B and power supply line PL1 and ground line SL, and is turned on / off by a signal SE from control device 30. System relay SR electrically connects battery B to power supply line PL1 and ground line SL when turned on by signal SE, and connects battery B to power supply line PL1 and ground when turned off by signal SE. Electrically disconnected from line SL. Capacitor C1 is connected between power supply line PL1 and ground line SL, and smoothes voltage fluctuations between power supply line PL1 and ground line SL.

  DC / DC converter 40 is connected between power supply line PL1 and ground line SL, and steps down the voltage from power supply line PL1 and outputs it to auxiliary battery 50. The auxiliary battery 50 is an auxiliary power supply for the motor driving device 100 and supplies auxiliary voltage to the control device 30 and other auxiliary devices not shown.

  Capacitor C2 is connected between power supply line PL2 and ground line SL, and smoothes voltage fluctuations between power supply line PL2 and ground line SL. Resistance element 60 is connected in parallel with capacitor C2 between power supply line PL2 and ground line SL. Resistor element 60 functions as a discharge circuit that discharges the electric charge of power supply line PL2 to ground line SL to step down the voltage of power supply line PL2 when the voltage level of power supply line PL2 is not controlled.

  Boost converter 10 boosts a DC voltage supplied from battery B through power supply line PL1, and outputs the boosted voltage to power supply line PL2. More specifically, boost converter 10 stores DC current from battery B by accumulating current flowing in accordance with switching operation of power transistor Q2 as magnetic field energy in reactor L based on signal PWC from control device 30. And the boosted voltage is output to the power supply line PL2 via the diode D1 in synchronization with the timing when the power transistor Q2 is turned off.

  Boost converter 10 lowers the DC voltage supplied from inverter 20 via power supply line PL2 to the voltage level of battery B based on signal PWC from control device 30, and reduces the reduced voltage to battery B and Output to the DC / DC converter 40.

  Further, boost converter 10 stops the switching operation of power transistors Q1, Q2 based on signal SDOWN from control device 30. Specifically, the power transistors Q1 and Q2 are turned off by an H (logic high) level signal SDOWN, and when receiving an L (logic low) level signal SDOWN, the power transistors Q1 and Q2 correspond to the signal PWC from the control device 30. Switching operation.

  Inverter 20 converts a DC voltage supplied from power supply line PL2 into a three-phase AC voltage based on signal PWM from control device 30, and drives motor generator MG. Thereby, motor generator MG is driven to generate torque specified by torque command value TR. Inverter 20 converts a three-phase AC voltage generated by motor generator MG in response to an external rotational force into a DC voltage based on signal PWM from control device 30, and converts the converted DC voltage to power supply line PL2. Output to.

  Voltage sensor 72 detects a voltage between power supply line PL 1 and ground line SL, that is, voltage VL on the primary side (low voltage side) of boost converter 10, and outputs the detected voltage VL to control device 30. Voltage sensor 74 detects a voltage between power supply line PL2 and ground line SL, that is, voltage VH on the secondary side (high voltage side) of boost converter 10, and outputs the detected voltage VH to control device 30. . Voltage sensor 76 detects auxiliary machine voltage VA of auxiliary battery 50 and outputs the detected auxiliary machine voltage VA to control device 30.

  Control device 30 is a signal for driving boost converter 10 based on torque command value TR and rotation speed MRN of motor generator MG received from outside, voltage VL from voltage sensor 72, and voltage VH from voltage sensor 74. PWC is generated, and the generated signal PWC is output to boost converter 10.

  In addition, control device 30 detects an abnormal state such as a decrease in auxiliary machine voltage VA, overvoltages of voltages VL and VH, and overheating of boost converter 10. Further, control device 30 generates a signal SDOWN for instructing stop of the switching operation of power transistors Q1 and Q2 in boost converter 10. Then, when detecting the above abnormal state, control device 30 outputs signal SDOWN to boost converter 10 at the H level.

  Further, control device 30 generates signal PWM for driving motor generator MG based on voltage VH from voltage sensor 74, motor current of motor generator MG, and torque command value TR, and generates the signal PWM. The signal PWM is output to the inverter 20.

  FIG. 2 is a functional block diagram relating to control of boost converter 10 in control device 30 shown in FIG. Referring to FIG. 2, control device 30 includes a voltage command calculation unit 112, a duty ratio calculation unit 114, a PWM signal conversion unit 116, and an abnormality processing unit 118.

  Voltage command calculation unit 112 receives torque command value TR of motor generator MG and motor rotation speed MRN from the outside. Voltage command calculation unit 112 calculates an optimum value (target value) of voltage VH based on torque command value TR and motor rotational speed MRN when motor generator MG is driven by power running, and calculates the calculated voltage VH Are output to the duty ratio calculation unit 114.

  In addition, voltage command calculation unit 112 calculates an optimum value (target value) of voltage VL based on torque command value TR and motor rotation speed MRN when motor generator MG is regeneratively driven, and the calculated voltage VL Are output to the duty ratio calculation unit 114.

  Further, voltage command calculation unit 112 receives signal HOLD from abnormality processing unit 118. Then, when the signal HOLD is at the H level, the voltage command calculation unit 112 does not take in the torque command value TR and the motor rotational speed MRN from the outside, and holds the value immediately before the signal HOLD becomes the H level.

  Duty ratio calculation unit 114 receives voltages VL and VH from voltage sensors 72 and 74, respectively, and receives a target value of voltage VL or a target value of voltage VH from voltage command calculation unit 112. Then, duty ratio calculation unit 114 calculates a duty ratio for setting voltage VH to the target value when motor generator MG is driven by powering, and outputs the calculated duty ratio to PWM signal conversion unit 116. .

  Further, duty ratio calculation unit 114 calculates a duty ratio for setting voltage VL to the target value when motor generator MG is being regeneratively driven, and outputs the calculated duty ratio to PWM signal conversion unit 116. .

  Further, duty ratio calculation unit 114 receives signal HOLD from abnormality processing unit 118. Then, when the signal HOLD is at the H level, the duty ratio calculation unit 114 does not take in the voltages VL and VH from the outside, and holds the value immediately before the signal HOLD becomes the H level.

  PWM signal conversion unit 116 generates a signal PWC for turning on / off power transistors Q1 and Q2 of boost converter 10 based on the duty ratio received from duty ratio calculation unit 114, and uses the generated signal PWC as a boost converter. It outputs to ten power transistors Q1, Q2.

  Note that increasing the on-duty of power transistor Q2 in the lower arm of boost converter 10 increases the power storage in reactor L, so that the boost rate of boost converter 10 increases. On the other hand, increasing the on-duty of power transistor Q1 in the upper arm increases the amount of discharge through power transistor Q1, so that the step-down rate of boost converter 10 increases.

  Abnormality processing unit 118 receives auxiliary machine voltage VA from voltage sensor 76, receives voltages VL and VH from voltage sensors 72 and 74, respectively, and detects temperature T of boost converter 10 detected by the temperature sensor from a temperature sensor (not shown). receive. When the abnormality processing unit 118 detects an abnormal state such as a decrease in the auxiliary machine voltage VA, an overvoltage of the voltages VH and VL, or an abnormal increase in the temperature T, the signal SDOWN for instructing the switching operation of the power transistors Q1 and Q2 to stop. Is set to H level and output to boost converter 10.

  In addition, when detecting the above abnormal state, the abnormality processing unit 118 prohibits data capture from the outside, and outputs an H level signal HOLD instructing the retention of the data value to the voltage command calculation unit 112 and the duty ratio calculation unit. To 114.

  Here, when the above abnormal state is resolved, the abnormality processing unit 118 sets the signal HOLD to the L level. However, when the motor generator MG is regeneratively driven, the abnormality processing unit 118 does not immediately set the signal SDOWN to the L level, and the voltage VH from the voltage sensor 74 reduces the component breakdown voltages of the DC / DC converter 40 and the system relay SR. After confirming that the signal level is lower, the signal SDOWN is set to L level. In other words, when the motor generator MG is regeneratively driven, the abnormality processing unit 118 connects the voltage VH on the secondary side (high voltage side) of the boost converter 10 to the primary side (low voltage side) of the boost converter 10. After confirming that the component breakdown voltage of the devices (hereinafter, these devices are also referred to as “low voltage side devices”) has been confirmed, the switching operation stop command of the power transistors Q1 and Q2 is canceled.

  FIG. 3 is a timing chart for explaining the concept of abnormality processing by the control device 30 shown in FIG. Referring to FIG. 3, when an abnormal flag indicating an abnormal state such as a decrease in auxiliary machine voltage VA becomes H level at time t1, signal SDOWN for instructing operation stop of boost converter 10 becomes H level. Thereby, boost converter 10 stops its operation. Here, the secondary side (high voltage side) voltage VH of the boost converter 10 is V1, and the step-down rate of the boost converter 10 is R1. The control device 30 holds the step-down rate at R1 while the abnormality flag is at the H level.

  It is assumed that voltage VH rises from V1 to V2 due to regenerative power generation by motor generator MG at time t2 in the abnormal state. At time t3, the abnormality is eliminated, and the abnormality flag becomes L level.

  Here, because control device 30 operates in a predetermined control cycle, control device 30 has step-down rate R1 held during an abnormal state for a time Δt corresponding to one control cycle immediately after the start of operation of boost converter 10. Perform the operation. On the other hand, the secondary side (high voltage side) voltage VH of boost converter 10 has risen to V2 after time t2.

  Then, like the conventional signal SDOWN, when the signal SDOWN is set to the L level at the time t3 when the abnormality is resolved and the abnormality flag becomes the L level, during the time Δt from the time t3 to the time t4, the boost converter 10 Since the increased voltage VH is stepped down at a step-down rate R1 smaller than the actual input / output voltage ratio, an unexpectedly high voltage is supplied to the primary side (low voltage side) of the boost converter 10. If the supplied voltage is higher than the component withstand voltage of the low-voltage side device disposed on the primary side (low voltage side) of the boost converter 10, these low-voltage side devices will be damaged.

  In contrast, in the embodiment of the present invention, the signal SDOWN is not immediately set to the L level at time t3 when the abnormality is resolved and the abnormality flag becomes the L level. At time t5, when voltage VH decreases to voltage V3 corresponding to the component breakdown voltage of the low-voltage side device due to discharge by resistance element 60, control device 30 sets signal SDOWN to L level and performs step-down operation of boost converter 10. Let it begin. Therefore, a voltage exceeding the component breakdown voltage of the low voltage side device is not supplied to the low voltage side device.

  FIG. 4 is a flowchart regarding abnormality processing by the control device 30 shown in FIG. Referring to FIG. 4, abnormality processing unit 118 of control device 30 includes auxiliary voltage VA from voltage sensor 76, voltage VL from voltage sensor 72, voltage VH from voltage sensor 74, and temperature T of boost converter 10. Based on the above, it is determined whether or not an abnormal state such as a decrease in the auxiliary machine voltage VA, an overvoltage of the voltages VH and VL, or an abnormal increase in the temperature T occurs (step S10). If abnormality processing unit 118 determines that an abnormality has not occurred (NO in step S10), the series of processing ends.

  On the other hand, when it is determined in step S10 that an abnormality has occurred (YES in step S10), abnormality processing unit 118 outputs signal SDOWN to the boost converter 10 at the H level to stop the operation of boost converter 10 (step S10). S20). Furthermore, abnormality processing unit 118 outputs signal HOLD at H level to voltage command calculation unit 112 and duty ratio calculation unit 114. Then, voltage command calculation unit 112 and duty ratio calculation unit 114 do not take in torque command value TR, motor rotation speed MRN, and voltages VL and VH from the outside, and retain the values immediately before the occurrence of an abnormality (step S30). ).

  Next, the abnormality processing unit 118 determines whether or not the generated abnormality has been resolved (step S40). If abnormality processing unit 118 determines that the abnormality has not been resolved (NO in step S40), it proceeds to step S20.

  On the other hand, when it is determined in step S40 that the abnormality has been resolved (YES in step S40), abnormality processing unit 118 sets signal HOLD to the L level. Then, voltage command calculation unit 112 starts taking in torque command value TR and motor rotation speed MRN, and duty ratio calculation unit 114 starts taking in voltages VL and VH from the outside (step S50). .

  Then, abnormality processing unit 118 determines whether or not voltage VH from voltage sensor 74 is lower than the component withstand voltage of the low-voltage side device connected to the primary side (low voltage side) of boost converter 10 (step S60). ). If abnormality processing unit 118 determines that voltage VH is equal to or higher than the component breakdown voltage of the low-voltage side device (NO in step S60), it waits until voltage VH falls below the component breakdown voltage of the low-voltage side device due to discharge by resistance element 60. . If abnormality processing unit 118 determines that voltage VH has fallen below the component withstand voltage of the low-voltage side device (YES in step S60), it sets signal SDOWN to L level and cancels the operation stop of boost converter 10 (step S70). .

  As described above, according to this embodiment, when the step-down operation of boost converter 10 is started after the abnormality is resolved, voltage VH on the secondary side (high voltage side) of boost converter 10 is referred to, and boost converter 10 After confirming that the voltage VH is lower than the component withstand voltage of the low voltage side device connected to the primary side (low voltage side), the signal SDOWN is set to L level to release the operation stop command to the boost converter 10. As a result, it is possible to prevent an overvoltage from being applied to the DC / DC converter 40.

  In the above embodiment, the low-voltage side device connected to the primary side (low voltage side) of the boost converter 10 is the DC / DC converter 40 or the system relay SR. If an inverter for an air conditioner and other devices are further connected, the pressure resistance of those components may be taken into consideration.

  In the above embodiment, the voltages VL and VH are detected by the voltage sensors 72 and 74, respectively. However, instead of the voltage sensor, the voltages VL and VH are calculated using a current sensor and a resistor. May be.

  In the above embodiment, the battery B is a chargeable / dischargeable secondary battery, but may be a fuel cell. A fuel cell is a DC power generation cell that obtains electrical energy from chemical reaction energy generated by a chemical reaction between a fuel such as hydrogen and an oxidant.

  In the above embodiment, boost converter 10 corresponds to “voltage converter” in the present invention, and the low-voltage side device corresponds to “electric load” in the present invention. Boost converter 10 and control device 30 correspond to “voltage conversion device” in the present invention. Battery B corresponds to “DC power supply” in the present invention, and inverter 20 corresponds to “driving device” in the present invention.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 is a schematic block diagram of a motor drive device according to an embodiment of the present invention. It is a functional block diagram regarding control of the boost converter in the control apparatus shown in FIG. It is a timing chart for demonstrating the concept of the abnormality process by the control apparatus shown in FIG. It is a flowchart regarding the abnormality process by the control apparatus shown in FIG.

Explanation of symbols

  10 boost converter, 20 inverter, 22 U-phase arm, 24 V-phase arm, 26 W-phase arm, 30 control device, 40 DC / DC converter, 50 auxiliary battery, 60 resistance element, 72, 74, 76 voltage sensor, 100 Motor drive unit, 112 Voltage command calculation unit, 114 Duty ratio calculation unit, 116 PWM signal conversion unit, 118 Abnormal processing unit, B battery, C1, C2 capacitor, L reactor, MG motor generator, Q1-Q8 power transistor, D1- D8 Diode, PL1, PL2 Power line, SL Ground line.

Claims (9)

A voltage converter that steps down a DC voltage and supplies it to an electrical load;
When a predetermined abnormality occurs, a command to stop the voltage converter is output to the voltage converter, and after confirming that the DC voltage is lower than a predetermined voltage level after the predetermined abnormality is resolved And a control device for canceling the command.   The voltage conversion device according to claim 1, wherein the predetermined voltage level is determined based on a component breakdown voltage of the electric load.   The voltage converter according to claim 1 or 2, further comprising a discharge circuit that reduces the DC voltage when the DC voltage is equal to or higher than the predetermined voltage level after the predetermined abnormality is resolved. DC power supply,
A driving device for driving the motor;
A voltage converter that steps down a DC voltage from the driving device and supplies the voltage to the DC power supply side;
An electrical load connected between the DC power source and the voltage converter;
When a predetermined abnormality occurs, a command to stop the voltage converter is output to the voltage converter, and after the predetermined abnormality is resolved, the DC voltage from the driving device is lower than a predetermined voltage level. A motor drive device comprising: a control device that cancels the command when the control is confirmed.   The motor driving apparatus according to claim 4, wherein the predetermined voltage level is determined based on a component breakdown voltage of the electric load.   The motor drive device according to claim 4, further comprising a discharge circuit connected between the drive device and the voltage converter.   The motor driving device according to claim 4, wherein the voltage converter further has a boosting function of boosting a DC voltage from the DC power supply and supplying the boosted voltage to the driving device. A method for controlling a voltage converter that steps down a DC voltage and supplies it to an electrical load,
A first step of outputting a command to stop the voltage converter to the voltage converter when a predetermined abnormality occurs;
A second step of determining whether or not the predetermined abnormality has been resolved;
A third step of determining whether or not the DC voltage is lower than a predetermined voltage level when it is determined in the second step that the predetermined abnormality has been resolved;
A voltage converter control method comprising: a fourth step of canceling the command when it is determined in the third step that the DC voltage is lower than the predetermined voltage level.   9. The voltage converter control method according to claim 8, wherein the predetermined voltage level is determined based on a component breakdown voltage of the electric load.

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