JP2007116790A - Inverter device - Google Patents

Abstract

Provided is an inverter device capable of suppressing heat generation of a capacitor and preventing damage to peripheral parts when a short-circuit fault occurs in a smoothing capacitor.
A current flowing through a smoothing capacitor is detected, and a short circuit failure of the smoothing capacitor is detected in a capacitor short circuit detection circuit. When the short circuit fault is detected, the gate drive circuit 348 is both rendered conductive to IGBT344 _-1 and _{345 -1} of the first arm _{343 -1} in the power module 342, the arm _{343 -1} and the bypass circuit. Since IGBT344 resistance of the bypass circuit by _-1 and _{345 -1} is very small, most of the short-circuit current flows through the bypass circuit. The power module 342 is usually so has a configuration in consideration of heat generation, heat generation of the arms 343 _-1 is less influence on the surroundings than when smoothing capacitor 150 generates heat.
[Selection] Figure 4

Description

  The present invention relates to an inverter device suitable for application to a motor drive device such as an electric vehicle.

For example, in a motor drive device that drives a motor of an electric vehicle or a hybrid vehicle, an inverter device using an inverter is widely used. In this inverter device, an electrolytic capacitor that can easily increase the withstand voltage and increase the capacity is usually used to smooth the DC power on the input side of the inverter that converts DC power from the battery into AC power. However, in recent years, ceramic capacitors have been increased in withstand voltage and capacity, so that use of the ceramic capacitor as a smoothing element for an inverter has been studied (for example, see Patent Document 1). Ceramic capacitors are advantageous in that they can be reduced in size and have low internal resistance compared to electrolytic capacitors.
JP 2001-197753 A

  However, when a ceramic capacitor fails due to deterioration, impact, or the like, the internal electrode is highly likely to cause a short circuit failure due to evaporation. In an inverter device that handles a large amount of electric power applied to a motor drive of a vehicle or the like, if a short circuit failure occurs in a ceramic capacitor for smoothing the power source of the inverter, a large current flows through the ceramic capacitor. If such a state continues, the capacitor may generate heat abnormally, which may increase the failure of the capacitor itself, and may damage surrounding components.

  The present invention has been made in view of such problems, and its purpose is to suppress the heat generation of the capacitor and prevent the peripheral parts from being damaged when a short circuit failure occurs in the smoothing capacitor of the inverter device. An object of the present invention is to provide an inverter device that can do this.

  In order to solve the above problems, an inverter device according to the present invention is an inverter device that converts DC power into AC power, an inverter that converts input DC power into AC power, and a DC power input of the inverter A smoothing capacitor provided between the lines; a failure detecting means for detecting a failure of the smoothing capacitor; and when a failure of the smoothing capacitor is detected, a bypass circuit is formed in parallel with the smoothing capacitor, and the smoothing capacitor Bypass means for reducing the current flowing through the smoothing capacitor by flowing at least part of the current flowing through the smoothing capacitor.

  In the inverter device having such a configuration, when a failure occurs in the smoothing capacitor, this is detected by the failure detection means, and a bypass circuit is formed by the bypass means based on the detection of the failure. As a result, at least part of the current that flows to the smoothing capacitor due to the failure also flows to the bypass circuit, and an abnormal large current is prevented from flowing to the smoothing capacitor. As a result, heat generation in the smoothing capacitor can be suppressed to some extent, and damage to peripheral parts can be prevented.

  As the bypass circuit, for example, it is preferable to separately provide a bypass circuit having a switch for switching between conduction and interruption of the circuit in parallel with the smoothing capacitor between the DC power input lines of the inverter. In this case, the bypass circuit control means is provided, and when a failure of the smoothing capacitor is detected, the bypass circuit control means controls the switch so that the bypass circuit becomes conductive.

Further, when the inverter has a configuration in which an arm having an upper arm and a lower arm each having a switching element is provided in parallel between the DC power input lines by the number of phases of AC power generated by the inverter. As a method of forming a bypass circuit when a failure of the smoothing capacitor is detected, at least one of the upper arm and the lower arm of the arm is turned on, and the arm is connected to the bypass circuit. It is also effective to form as.
In this case, the switching elements of the upper arm and the lower arm of all the arms included in the inverter may be turned on so that all the arms serve as bypass circuits.

  ADVANTAGE OF THE INVENTION According to this invention, when a short circuit fault arises in the smoothing capacitor of an inverter apparatus, the inverter apparatus which can suppress the heat generation of a capacitor | condenser and can prevent a peripheral component from being damaged can be provided.

First Embodiment As a first embodiment of the present invention, an inverter device applied to a motor drive device such as an electric vehicle or a hybrid vehicle, particularly when an abnormality of a smoothing capacitor is detected, power to the smoothing capacitor An inverter device configured to stop the supply of power will be described.
FIG. 1 is a diagram showing the configuration of the motor drive device.
A motor drive device 100 shown in FIG. 1 includes a DC power supply 110, a high-voltage relay 120, and an inverter device 130. In FIG. 1, a motor 510 is a motor to be driven by the motor driving device 100, and a vehicle control controller 520 is a higher-level control device of the motor driving device 100 and a control device that controls the entire vehicle.

  The DC power supply 110 is a power supply for driving the motor 510 via the inverter device 130, and outputs high-voltage DC power of several tens to several hundreds V or more.

The high voltage relay 120 switches whether to apply high voltage DC power output from the DC power supply 110 to the inverter device 130. The high power relay 120 is controlled by a vehicle controller 520 that controls the entire vehicle.
In the motor driving apparatus 100, an electric system (high electric system) that handles high voltage and large current power for actually driving the motor 510 and an electric system for signal processing (weak electric system) are actually used on the circuit. It is also clearly distinguished in the arrangement and configuration. For example, an element such as the high-power relay 120 is used as a means for connecting these, and particularly as means for actually applying power to the high-power system according to the signal processing result of the weak-power system.

  As described above, the high-power relay 120 is an element that links the high-power system and the weak-power system, and is a very important element that is a main switch of the motor 510 that drives the vehicle and the driving device 100 thereof. From such a point, only the vehicle control controller 520, which is the controller having the highest authority and controlling the entire vehicle, controls on / off of the high voltage relay 120. In other words, for example, the high-power relay 120 cannot be controlled from a control circuit (signal processing device) provided in an inverter device 130 or the like described later.

Inverter device 130 generates AC power for driving the motor for driving the motor from the input DC power and applies it to motor 510. The inverter device 130 is controlled based on a control signal from the vehicle controller 520, and generates AC drive power for driving the motor with desired characteristics (for example, desired rotation speed, desired torque, etc.).
As illustrated, the inverter device 130 includes a power module 142, a gate drive circuit 148, a smoothing capacitor 150, a capacitor short-circuit detection circuit 160, and a motor control circuit 180.

The power module 142 is a circuit that generates three-phase AC power for driving the motor, and controls the motor 510 by PWM (Pulse Width Modulation) control. Power module 142, between the two input lines of the DC power, and circuit ₁₄₃ -1 ～143 _-3 of 3 arm component corresponding to each phase are connected in parallel. Each arm ₁₄₃ -i (i = _1~3) is, IGBT connected in series _{(Insulated Gate Bipolar Transistor) 144 -i} , 145 -i, _and, IGBT144 _-i, antiparallel to each of the _{145 -i} The diodes 146 _-i and 147 _-i are connected to each other. In each arm 143- _i , the IGBT 144- _i and the diode 146- _i constitute an upper arm, and the IGBT 145- _i and the diode 147- _i constitute a lower arm.

IGBT144 _-1 ~144 _-3 of the power module 142, ₁₄₅ -1 to 145 _-3 are controlled by a gate drive circuit 148.
The gate drive circuit 148 based on the PWM control signal input from the motor control circuit 180, circuit 3 arm component corresponding to each phase ₁₄₃ -1 ～143 _-3 IGBT144 _-1 ~144 _{-3, 145 -1} the 145 _-3, by turning on / off each at a desired timing to produce the desired three-phase AC drive power characteristics (voltage, frequency, etc.) for driving the motor 510 in an arbitrary state.

  The smoothing capacitor 150 is a capacitive element provided between the DC input lines of the inverter device 130 in order to mainly smooth the voltage fluctuation of the input DC power supply. In this embodiment, the smoothing capacitor 150 is a large-capacity ceramic capacitor.

  The capacitor short circuit detection circuit 160 detects a short circuit of the smoothing capacitor 150, and outputs at least the detection result to the vehicle controller 520 via the motor control circuit 180 when a short circuit is detected. The short circuit of the smoothing capacitor 150 can be detected by detecting, for example, the current flowing through the smoothing capacitor 150, the fluctuation of the voltage across the smoothing capacitor 150, the heat generation of the smoothing capacitor 150, and the like. In the present embodiment, the capacitor short circuit detection circuit 160 detects a short circuit of the capacitor short circuit detection circuit 160 by checking the current flowing through the smoothing capacitor 150.

The motor control circuit 180 generates an appropriate motor driving voltage and applies it to the motor 510 so that the motor 510 is driven in an appropriate state based on an instruction from the vehicle controller 520, that is, in the inverter device 130. Thus, the entire inverter device 130 is controlled. Specifically, a PWM control signal is output to the gate drive circuit 148 so that the IGBTs 144 _{-1 to} 144 _-3 and 145 _{-1 to} 145 _-3 are appropriately turned on / off by the control of the gate drive circuit 148. .
The motor control circuit 180 is a vehicle control controller that is a higher-level control device outside the motor driving device 100 when a signal indicating that at least a smoothing capacitor 150 short-circuit abnormality has been detected is input from the capacitor short-circuit detection circuit 160. Notify 520.

  As described above, the motor 510 is a motor to be controlled by the motor driving device 100, and is a power source for running the vehicle.

Further, the vehicle controller 520 is a higher-level control device of the motor drive device 100 as described above, and is a control device that controls the entire vehicle including the motor drive device 100. The vehicle controller 520 generates a control signal and outputs the control signal to the motor control circuit 180 in order to appropriately drive the vehicle in accordance with, for example, a driving operation by the driver of the vehicle.
Further, when a short circuit failure occurs in the smoothing capacitor 150 of the motor drive device 100 and the capacitor short circuit detection circuit 160 detects this, the vehicle control controller 520 is notified via the motor control circuit 180 of that fact. The When the notification indicating that the smoothing capacitor 150 is short-circuited is made, the vehicle controller 520 switches off the high-power relay 120 so as to cut off the supply of power from the DC power source 110 to the inverter device 130 (motor drive device 100). .

The operation of the motor driving apparatus 100 having such a configuration will be described.
When the high-power relay 120 is closed under the control of the vehicle controller 520, high-voltage DC power from the DC power supply 110 is supplied to the inverter device 130.
The vehicle controller 520 also issues a torque command to the motor control circuit 180. Based on this, the motor control circuit 180 outputs a PWM control signal to the gate drive circuit 148, and the gate drive circuit 148 is based on the PWM control signal from the capacitor short circuit detection circuit 160, and the switching element (IGBT) in the power module 142. 144 _-1 to 144 _-3 to control the ₁₄₅ -1 145 _-3 respective on / off. As a result, three-phase AC driving power having a desired characteristic for driving the motor 510 in a desired state is generated and applied to the motor 510.

It is assumed that a short circuit failure has occurred in the smoothing capacitor 150 when the motor driving apparatus 100 is operating as described above. After the smoothing capacitor 150 is charged during normal operation, no current flows through the smoothing capacitor 150. However, when a short circuit failure occurs in the smoothing capacitor 150, the charge charged in the smoothing capacitor 150 is discharged. A large current flows immediately after the occurrence of a short circuit failure. In addition, after the discharge of the smoothing capacitor 150 is completed to some extent, a current corresponding to the power applied from the DC power supply 110 to the inverter device 130 flows, but the resistance due to the short-circuit failure of the smoothing capacitor 150 is usually very small. A large current flows through the smoothing capacitor 150 in the same manner as immediately after the short circuit and continues to flow while power is applied.
By monitoring such a current flowing in the smoothing capacitor 150 in the capacitor short-circuit detection circuit 160, when the smoothing capacitor 150 is in a failure state, that fact is immediately detected in the capacitor short-circuit detection circuit 160. That is, by detecting that an unusable large current flows to the smoothing capacitor 150, a short circuit failure of the smoothing capacitor 150 can be easily detected.

  When the capacitor short circuit detection circuit 160 detects a short circuit failure of the smoothing capacitor 150, the capacitor short circuit detection circuit 160 outputs a signal to that effect to the motor control circuit 180. The motor control circuit 180 notifies the vehicle control controller 520 which is a higher-level control device. As a result, the high-power relay 120 is opened under the control of the vehicle controller 520, the supply of power from the DC power supply 110 to the inverter device 130 is stopped, and the short-circuit current flowing through the smoothing capacitor 150 is also stopped.

  As described above, in the motor drive device 100 of the first embodiment, when the smoothing capacitor 150 has a short-circuit failure, this can be detected, and the application of power to the smoothing capacitor 150 can be stopped. It is possible to prevent a large current from continuing to flow.

Second Embodiment A second embodiment of the present invention will be described with reference to FIGS.
In the present embodiment as well, as in the first embodiment, the present invention will be described by exemplifying a motor drive device to which the inverter device of the present invention used for driving a motor in an electric vehicle or a hybrid vehicle is applied. .
In the following description, the same components as those of the motor drive device 100 of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and description thereof is omitted. Also, the description of the same operation and action as those of the motor drive device 100 of the first embodiment will be omitted. Hereinafter, the motor drive device of the second embodiment will be described focusing on differences from the motor drive device 100 of the first embodiment.

FIG. 2 is a circuit diagram showing a configuration of a motor drive device 200 according to the second embodiment of the present invention.
A motor drive device 200 shown in FIG. 2 includes a DC power supply 110, a high-voltage relay 120, and an inverter device 230, and drives the motor 510 based on control from the vehicle controller 520.
The configuration, operation, and operation of the DC power supply 110, the high voltage relay 120, the power module 142 of the inverter device 230, the gate drive circuit 148 and the smoothing capacitor 150, the motor control circuit 180, the motor 510, and the vehicle controller 520 are described above. This is the same as the motor drive device 100 of one embodiment.
The motor drive device 200 according to the second embodiment is different from the first embodiment in that a bypass circuit 270 is provided in the inverter device 230 and the configuration of the capacitor short-circuit detection circuit 260. The capacitor short circuit detection circuit 260 of the motor drive device 200 has a function of controlling a switch in the bypass circuit 270 in addition to the function of detecting a short circuit failure of the smoothing capacitor 150 in the same manner as the capacitor short circuit detection circuit 160 of the first embodiment. Have

  The bypass circuit 270 is a circuit in which a resistor 271 and a switch 272 are connected in series as shown in the figure, arranged in parallel with the smoothing capacitor 150 between the two DC power input lines of the motor driving device 200. The resistor 271 is an element that has a resistance value slightly smaller than or approximately the same as the resistance value of the smoothing capacitor 150 at the time of a short circuit failure and that can carry a large current (for example, several thousand amperes). The switch 272 is an on / off switch that switches whether a current is passed through the bypass circuit 270. The switch 272 is directly controlled to be turned on / off by the capacitor short-circuit detection circuit 260 and is turned into a closed state (on state), whereby a current due to the DC power applied to the inverter device 230 flows to the bypass circuit 270. In the open state (off state), no current flows through the bypass circuit 270 and the bypass circuit 270 does not affect the operation of the inverter device 230 at all.

Similar to the motor control circuit 180 of the first embodiment, the capacitor short-circuit detection circuit 260 detects a short-circuit failure of the smoothing capacitor 150 by detecting the current flowing through the smoothing capacitor 150, and sends a signal indicating that to the motor control circuit. Output to 180.
When the capacitor short circuit detection circuit 260 further detects a short circuit failure of the smoothing capacitor 150, the capacitor short circuit detection circuit 260 turns on the switch 272 of the bypass circuit 270 so that a current flows through the bypass circuit 270. By doing so, a large current flowing through the smoothing capacitor 150 after the smoothing capacitor 150 is short-circuited is divided and flows into the smoothing capacitor 150 and the bypass circuit 270, and the current flowing through the smoothing capacitor 150 is reduced. be able to.

The operation of the motor drive device 200 having such a configuration will be described.
The normal operation of the motor drive device 200 when there is no abnormality is the same as the operation of the motor drive device 100 of the first embodiment. That is, when the high-power relay 120 is closed under the control of the vehicle controller 520, high-voltage DC power from the DC power supply 110 is supplied to the inverter device 230. The switching element _(IGBT) 144 -1 to 144 _-3 in the power module _142, 145 -1 to 145 _-3 on / off controlled by a gate drive circuit 148. As a result, three-phase AC driving power for driving the motor 510 in a desired state is generated. At this time, since the switch 272 of the bypass circuit 270 is in an open state (off state), no current flows through the bypass circuit 270.

In such a motor drive device 200, the operation when the smoothing capacitor 150 is short-circuited will be described with reference to FIG.
When a short circuit failure occurs in the smoothing capacitor 150 while the motor driving device 200 is operating normally, the charge charged in the smoothing capacitor 150 is discharged, and smoothing is performed as shown at times t1 to t3 in FIG. A large short-circuit current flows through the capacitor 150.
When such a current flows, the capacitor short circuit detection circuit 260 detects this, and outputs a short circuit detection signal to the control circuit 180 at time t2, for example, as shown in FIG.

Further, when the capacitor short circuit detection circuit 260 detects a short circuit failure of the smoothing capacitor 150, the capacitor short circuit detection circuit 260 immediately switches the switch 272 of the bypass circuit 270 to enable the bypass circuit 270. As a result, for example, as shown in FIG. 3C, the switch is switched at a time t3 after a delay time for switching to some extent, and then the current is supplied to the bypass circuit 270 as shown in FIG. Begins to flow.
Further, when the control circuit 180 outputs a signal indicating that a short circuit failure of the smoothing capacitor 150 has occurred to the vehicle controller 520, the high-voltage relay 120 is opened at time t4 as shown in FIG. The supply of power from the power supply 110 to the inverter device 230 is stopped, and the short-circuit current flowing through the smoothing capacitor 150 as shown in FIG.

  As described above, the motor driving device 200 according to the second embodiment includes the bypass circuit 270 for causing a short-circuit current to flow when the smoothing capacitor 150 is short-circuited in the inverter device 230, and the capacitor in the inverter device 230. When the short circuit detection circuit 260 detects a short circuit failure of the smoothing capacitor 150, it directly controls the switch 272 of the bypass circuit 270 to enable the bypass circuit 270. Therefore, the short-circuit current flowing through the smoothing capacitor 150 can be reduced as soon as the short-circuit of the smoothing capacitor 150 is detected. The heat generation of the smoothing capacitor 150 and the influence on surrounding components due to the large current flowing through the smoothing capacitor 150 immediately after the short-circuit Can be prevented.

  For example, in the motor drive device 100 of the first embodiment, when the short circuit failure is detected by the capacitor short circuit detection circuit 160, the high voltage relay 120 is turned off via the motor control circuit 180 and the vehicle control controller 520, and the inverter device 130 is connected. Since the input of electric power is stopped, as shown in FIG. 3E, for example, it takes time t4 to stop the input of electric power to the inverter device 130. However, the motor driving device 200 of the present embodiment is stopped. In FIG. 3, since the capacitor short-circuit detection circuit 260 directly controls the switch 272 of the bypass circuit 270, the bypass circuit 270 can be made effective at time t3 as shown in FIG. As a result, the current flowing through the smoothing capacitor 150 can be reduced significantly.

  In this embodiment, the capacitor short-circuit detection circuit 160 is configured to directly switch the switch 272. However, the capacitor short-circuit detection circuit 160 only has a function of notifying the motor control circuit 180 when a short-circuit failure of the smoothing capacitor 150 is detected. The motor control circuit 180 may switch the switch 272. Both the capacitor short circuit detection circuit 160 and the motor control circuit 180 are signal processing circuits in the inverter device 130, and the time until the bypass circuit 270 is validated is almost the same regardless of which is switched. That is, even if the motor control circuit 180 is configured to switch the switch 272, a larger short-circuit current flows through the smoothing capacitor 150 as compared with the case where the vehicle controller 520 switches the high-power relay 120 to cut off power to the inverter device 130. It is the same that the time can be greatly shortened.

Third Embodiment A third embodiment of the present invention will be described with reference to FIGS.
Also in the present embodiment, the present invention will be described by exemplifying a motor driving device used in an electric vehicle or the like as in the first embodiment and the second embodiment.
In addition, about the same structure, operation | movement, and effect | action as the motor drive device 100 of 1st Embodiment, while using the same code | symbol as 1st Embodiment, the description is abbreviate | omitted.

FIG. 4 is a circuit diagram showing a configuration of a motor drive device 300 according to the third embodiment of the present invention.
A motor driving device 300 shown in FIG. 4 has a DC power source 110, a high-voltage relay 120, and an inverter device 330, and is controlled by the vehicle controller 520 to drive the motor 510.
The configurations, operations, and actions of the DC power supply 110, the high voltage relay 120, the smoothing capacitor 150 of the inverter device 330, the capacitor short circuit detection circuit 160 of the inverter device 330, the motor 510, and the vehicle controller 520 are the motor drive of the first embodiment described above. It is the same as the device 100.

The motor drive device 300 according to the third embodiment is configured by short-circuiting a switching element for one arm of the power module 342 of the inverter device 330, corresponding to the bypass circuit 270 of the motor drive device 200 of the second embodiment. To do.
That is, in the motor drive device 300, when the short-circuit failure of the smoothing capacitor 150 by the capacitor short-circuit detecting circuit 160 is detected, the first upper arm of the arm _{343 -1} IGBT344 _-1 and lower arms of the power module 342 by turning on both the IGBT345 _-1 of, it is short-circuited between the DC input lines of the inverter 330, constituting the first arm _{343 -1} as a bypass circuit. And the short-circuit current flowing through the smoothing capacitor 150, to flow to the first arm _{343 -1.}

The configuration of the power module 342 may include a function for preventing overcurrent exceeding the rating from flowing through each arm 343- _i (i = 1 to 3). In the power module 342 of the motor driving device 300, when a short circuit failure of the power module 342 is detected in the capacitor short circuit detection circuit 160, such an overcurrent detection function is masked (not to function). Accordingly, previously configured and can continue to flow intentionally large current to the first arm 343 _-1 became bypass circuit.

Further, the arm _{343 -1} of the inverter 340 is bypassed the short-circuit current, more large current to flow more than the rated to the intentionally stopped IGBT344 _-1 and _{345 -1} a function of preventing an overcurrent as described above In such a case, the device may be broken. However, these elements are usually sealed in a resin case of the power module 342 with a protective material such as gel, and a cooling design is also made in consideration of heat generation during normal inverter operation. Therefore, even if a large current flows and breaks down, there is little possibility of generating heat and affecting the surroundings. At least, the influence of the smoothing capacitor 150 on the surroundings is smaller than when the smoothing capacitor 150 generates heat due to a short circuit.

The gate drive circuit 348 of the motor drive device 300 based on the PWM control signal input from the motor control circuit 380 controls the _{IGBT344 -1 ~344 -3, 345 -1 ~345} -3 of the power module 342 optionally characteristics (voltage, frequency, etc.) to generate a three-phase AC driving power, when the short-circuit fault of the smoothing capacitor 150 is detected in the capacitor short-circuit detection circuit 160, the upper arm of the first arm 343 _-1 by turning on both the IGBT345 _-1 of IGBT344 _-1 and the lower arm, thereby short-circuit the DC input lines of the inverter device 330, causing flow the short-circuit current flowing through the smoothing capacitor 150 to the first arm _{343 -1} .

The operation of the motor driving apparatus 300 having such a configuration will be described.
The normal operation when there is no abnormality is the same as the operation of the motor drive device 100 of the first embodiment. That is, when the high voltage relay 120 is closed by the control of the vehicle controller 520, a high voltage DC power from the DC power source 110 is supplied to the inverter device 330, the switching element in the power module 342 _(IGBT) 344 -1 ~344 _{- 3} , 345 _{-1 to} 345 _-3 are controlled by the gate drive circuit 348 to generate three-phase AC drive power for driving the motor 510 in a desired state.

In such a motor drive device 300, the operation when the smoothing capacitor 150 has a short circuit failure will be described with reference to FIG.
When a short circuit failure occurs in the smoothing capacitor 150 while the motor driving device 300 is operating normally, the electric charge charged in the smoothing capacitor 150 is discharged, so as shown at time t1 to t4 in FIG. A large short-circuit current flows through the smoothing capacitor 150.
When such a current flows, the capacitor short circuit detection circuit 160 detects this, and outputs a short circuit detection signal to the control circuit 380 at time t2, for example, as shown in FIG.

The motor control circuit 380, when detecting the short-circuit failure of the smoothing capacitor 150, immediately to enable the first arm _{343 -1} of the power module 342 as a bypass circuit for short-circuit current, the first arm _{343 -1} IGBT344 outputs _-1 and _{345 -1} both a control signal for turning on the gate drive circuit 348. As a result, the gate drive circuit 348, as shown in FIG. 5 (C) and FIG. 5 (D), the gate signal for turning on the IGBT344 _-1 of the upper arm, and, the IGBT345 _-1 of the lower arm a gate signal for turning on, applied to each IGBT344 _-1 and _{345 -1} at time t3. Thus, for example, FIG. 5 (A), the as shown in FIG. 5 (C) and FIG. 5 (D), the switch is switched at time t4, a current bypass circuit formed on the first arm _{343 -1} Start flowing.

  In addition, when the control circuit 380 outputs a signal indicating that a short circuit failure of the smoothing capacitor 150 has occurred to the vehicle controller 520, the high-voltage relay 120 is opened at time t5, as shown in FIG. The supply of power from the power supply 110 to the inverter device 330 is stopped, and the short-circuit current flowing through the smoothing capacitor 150 is also stopped as shown in FIG.

Thus, a motor drive device 300 of the third embodiment, when the smoothing capacitor 150 in the inverter device 330 has a short circuit fault, forming a bypass circuit for bypassing the short-circuit current to the arm 343 _-1 of the inverter 340 Like to do. Therefore, the short-circuit current flowing through the smoothing capacitor 150 can be reduced as soon as the short-circuit of the smoothing capacitor 150 is detected, and the heat generation of the smoothing capacitor 150 and the influence on surrounding components due to the large current flowing through the smoothing capacitor 150 immediately after the short-circuit. Can be prevented.

In particular, IGBT344 _-1 and _{345 -1} switching is a switching of the semiconductor switching element, the switching of the high voltage relay 120 in the first embodiment, much faster than the switching of the switch 272 in the second embodiment, substantially Done in an instant. The delay time until the formation of the bypass circuit in the third embodiment is simply a signal transmission delay time from the capacitor short-circuit detection circuit 160 to the gate drive circuit 348, and is about several μsec although it varies depending on the element configuration. Therefore, even when compared with the first embodiment and the second embodiment, a bypass circuit can be formed immediately after the detection of the short-circuit fault of the smoothing capacitor 150, and the time during which a large current flows through the smoothing capacitor 150 can be shortened. it can.

Further, when the bypass circuit is enabled, the first short-circuit current which has been flowing to the arm 343 _-1 of the power module 342, a short-circuit and smoothing capacitor 150, is shunted according to the resistance ratio of the bypass circuit. However, the bypass circuit of the present embodiment is formed by a series circuit of IGBT344 _-1 and _{345 -1,} resistance when you turn on these IGBT is sufficiently small. Therefore, most of the short-circuit current will flow into the bypass circuit by the arm _{343 -1} of the inverter 340. That is, almost no current flows through the shorted smoothing capacitor 150. Therefore, the heat generation of the smoothing capacitor 150 can be prevented more effectively than in the above-described embodiments.

In the third embodiment, two IGBTs 344 _-1 and 345 _-1 corresponding to one arm (first arm 343 _-1 ) among the three arms included in the power module 342 of the inverter device 330 are provided. Used to form a bypass circuit. However, the bypass circuit may be configured using two arms or all three arms. By forming a plurality of bypass circuits in this way, the current flowing through one bypass circuit can be reduced, and heat generation can be further reduced.

  In addition, this Embodiment was described in order to make an understanding of this invention easy, and does not limit this invention at all. Each element disclosed in the present embodiment includes all design changes and equivalents belonging to the technical scope of the present invention, and various suitable modifications are possible.

FIG. 1 is a circuit diagram showing a configuration of a motor drive device according to a first embodiment of the present invention. FIG. 2 is a circuit diagram showing the configuration of the motor drive device according to the second embodiment of the present invention. FIG. 3 is a timing chart for explaining the operation of the motor drive device shown in FIG. FIG. 4 is a circuit diagram showing the configuration of the motor drive device according to the third embodiment of the present invention. FIG. 5 is a timing chart for explaining the operation of the motor drive device shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100,200,300 ... Motor drive device 110 ... DC power supply 120 ... High-voltage relay 130, 230, 330 ... Inverter device 142, 342 ... Power module
143, 343 ... Arm
144, 145, 344, 345 ... IGBT
146, 147, 346, 347 ... Diodes 148, 348 ... Gate drive circuit 150 ... Smoothing capacitor 160, 260 ... Capacitor short circuit detection circuit 270 ... Bypass circuit
271: Resistance
272 ... Switch 180, 380 ... Motor control circuit 510 ... Motor 520 ... Vehicle control controller

Claims (4)

An inverter device that converts DC power to AC power,
An inverter that converts input DC power into AC power;
A smoothing capacitor provided between the DC power input lines of the inverter;
A failure detecting means for detecting a failure of the smoothing capacitor;
When a failure of the smoothing capacitor is detected, a bypass circuit is formed in parallel with the smoothing capacitor, and the current flowing through the smoothing capacitor is reduced by flowing at least part of the current flowing through the smoothing capacitor through the bypass circuit. An inverter device comprising: bypass means for allowing The bypass means includes
A circuit in parallel with the smoothing capacitor that connects the DC power input lines of the inverter, and includes a bypass circuit that includes a switch for switching between conduction and interruption of the circuit;
The inverter device according to claim 1, further comprising: bypass circuit control means for controlling the switch so that the bypass circuit becomes conductive when a failure of the smoothing capacitor is detected. The inverter has an arm having an upper arm and a lower arm, each having a switching element, in parallel between the DC power input lines for the number of phases of AC power generated by the inverter,
The bypass means turns on each switching element of the upper arm and the lower arm of at least one of the arms when a failure of the smoothing capacitor is detected, and forms the arm as the bypass circuit The inverter device according to claim 1, wherein: The bypass means turns on the switching elements of the upper arm and the lower arm of all the arms included in the inverter, and uses all the arms as the bypass circuit. The inverter device described in 1.

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