JP2017034768A - Load drive device - Google Patents

Abstract

A load driving device capable of realizing three-phase ON control when a short circuit occurs in a switching element included in a three-phase inverter. An ECU 300 identifies a switching element in a short circuit state, and identifies a short circuit state among upper and lower switching elements included in an arm circuit other than the arm circuit including the identified short circuit switching element. The inverter 14 is controlled so that the drive signal is output to the switching element at the same stage as the switching element of the first and the output of the drive signal to the specified short-circuited switching element is not executed. [Selection] Figure 1

Description

  The present invention relates to a load driving device, and more particularly to a load driving device including a three-phase inverter.

  Patent Document 1 discloses a vehicle drive device including a three-phase inverter. In this vehicle drive device, each of the three arm circuits included in the three-phase inverter has an upper IGBT (Insulated Gate Bipolar Transistor) and a lower IGBT. In this vehicle drive device, when one of the plurality of IGBTs included in the three-phase inverter is short-circuited, the short-circuited IGBT is specified. When the short-circuited IGBT is identified, all the IGBTs provided in the same stage as the short-circuited IGBT are electrically connected, and the retreat travel is executed in that state. Such control for electrically connecting all IGBTs provided in the same stage as the short-circuited IGBT is referred to as three-phase ON control. With the three-phase ON control, an overcurrent in the inverter due to the short circuit of the IGBT can be suppressed.

JP 2009-278791 A

  However, Patent Document 1 does not disclose a specific method for electrically conducting all IGBTs provided in the same stage as a short-circuited IGBT. The inventors of the present invention have found that a fail signal is generated when a drive signal is input to all three-phase switching elements including a short-circuited switching element when realizing three-phase on control. When the fail signal is generated, the three-phase inverter is shut down. Therefore, in this case, the three-phase on control cannot be realized.

  The present invention has been made to solve such a problem, and the object thereof is to realize three-phase on control when a short circuit occurs in a switching element included in the three-phase inverter. It is to provide a load driving device.

  A load driving device according to an aspect of the present invention includes a three-phase inverter and a control device. The control device controls the three-phase inverter so that the three-phase inverter is shut down when the fail signal is input. The fail signal is generated when a drive signal is input to a short-circuited switching element among the upper and lower switching elements provided in the arm circuit of each phase of the three-phase inverter. The control device specifies a switching element in a short circuit state. The control device then switches to the switching element in the same stage as the identified short-circuited switching element among the upper and lower switching elements included in the arm circuit other than the arm circuit including the identified short-circuited switching element. The three-phase inverter is controlled so that the output of the drive signal is executed and the output of the drive signal to the specified short-circuited switching element is not executed.

  In this load driving device, when a short circuit occurs in the switching element included in the three-phase inverter, no drive signal is input to the switching element in the short circuit state. Therefore, no fail signal is generated and the three-phase inverter is not shut down. On the other hand, a drive signal is input to the other switching element in the same stage as the short-circuited switching element. As a result, according to such a configuration, all the switching elements provided in the same stage as the shorted switching elements can be electrically connected, and three-phase on control can be realized.

  According to the present invention, it is possible to provide a load driving device capable of realizing three-phase ON control when a short circuit occurs in a switching element included in a three-phase inverter.

1 is an overall configuration diagram showing an electrical configuration of a hybrid vehicle. It is a figure for demonstrating the pattern in which a fail signal is produced | generated by the drive circuit of a switching element. It is a flowchart which shows the transfer operation | movement to three-phase on running at the time of a switching element short circuit.

  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.

(Configuration of hybrid vehicle)
FIG. 1 is an overall configuration diagram showing an electrical configuration of a hybrid vehicle 100 shown as an example of an electric vehicle equipped with a load driving device according to this embodiment. Referring to FIG. 1, hybrid vehicle 100 includes motor generators MG1 and MG2, an engine ENG, inverters 14 and 31, a DC power supply 140, and an ECU 300. In hybrid vehicle 100, DC power supplied from DC power supply 140 is converted into AC power in inverter 31, and motor generator MG2 is driven by the AC power. Thereby, the hybrid vehicle 100 travels. In hybrid vehicle 100, AC power is generated by obtaining power from engine ENG and driving motor generator MG1. The generated AC power is converted into DC power in the inverter 14, and the DC power is supplied to the DC power supply 140.

  Engine ENG and motor generators MG1, MG2 are coupled to power split device PSD. Hybrid vehicle 100 travels by driving force from at least one of engine ENG and motor generator MG2.

  Motor generators MG1 and MG2 are AC rotating electric machines. For example, motor generators MG1 and MG2 are three-phase AC synchronous motors in which a permanent magnet is embedded in a rotor.

  Motor generator MG1 generates back electromotive force using the kinetic energy of engine ENG divided by power split device PSD (power generation). The generated power is supplied to the DC power supply 140.

  Motor generator MG2 generates a driving force using at least one of the electric power stored in DC power supply 140 and the electric power generated by motor generator MG1. This driving force is used for traveling of the hybrid vehicle 100. Motor generator MG2 operates as a regenerative brake that converts braking energy into electric power. The electric power generated by motor generator MG2 is supplied to DC power supply 140.

  Power split device PSD distributes power among motor generators MG1, MG2 and engine ENG. For example, as the power split device PSD, a planetary gear mechanism having three rotation shafts of a sun gear, a planetary carrier, and a ring gear can be used. These three rotary shafts are connected to the rotary shafts of engine ENG and motor generators MG1, MG2, respectively.

  DC power supply 140 is a chargeable / dischargeable lithium ion secondary battery. Note that the DC power supply 140 is not limited to a lithium ion secondary battery, and may be a nickel hydride secondary battery, for example. The DC power supply 140 supplies DC power to the inverters 31 and 14. The DC power supply 140 is charged by receiving DC power supplied from the inverters 14 and 31. The DC power supplied from the inverters 14 and 31 is supplied to the DC power supply 140 after being smoothed by the smoothing capacitor C2. Smoothing capacitor C2 is connected between positive electrode line VL and negative electrode line SL.

  Inverters 14 and 31 are connected to motor generators MG1 and MG2, respectively. Inverters 14 and 31 are three-phase inverters. Since the inverters 14 and 31 have the same configuration, the inverter 14 will be described here.

  Inverter 14 includes three arm circuits. That is, inverter 14 includes a U-phase arm 15, a V-phase arm 16, and a W-phase arm 17. U-phase arm 15, V-phase arm 16, and W-phase arm 17 are provided in parallel between positive electrode line VL and negative electrode line SL.

  U-phase arm 15 includes switching elements Q1, Q2 connected in series. V-phase arm 16 includes switching elements Q3 and Q4 connected in series. W-phase arm 17 includes switching elements Q5 and Q6 connected in series. That is, each phase arm has an upper switching element (Q1, Q3, Q5) and a lower switching element (Q2, Q4, Q6). Further, diodes D1 to D6 are connected in antiparallel to the switching elements Q1 to Q6, respectively. For example, an IGBT is applied as the switching element. Switching elements Q1-Q6 are on / off controlled (switching controlled) in response to switching control signal PWMI1 input from ECU 300.

  The end of the U-phase coil of motor generator MG1 is connected to the intermediate point of switching elements Q1, Q2 via conductive wire 18. An end portion of the V-phase coil is connected to an intermediate point between the switching elements Q3 and Q4 via a conductive wire 19. An end portion of the W-phase coil is connected to an intermediate point of switching elements Q5 and Q6 through conductive wire 20.

  A driving circuit 40 is connected to each of the switching elements Q1 to Q6. When the switching control signal PWMI1 is input, the drive circuit 40 outputs a drive signal to the corresponding switching element. Thereby, the switching element is electrically conducted. The drive circuit 40 will be described in detail later.

  When an abnormality occurs in the inverter 14, a fail signal FINV is generated. Fail signal FINV is output to ECU 300. The cause of the generation of the fail signal FINV and the operation after the generation of the fail signal FINV will be described in detail later.

  ECU 300 controls inverters 14 and 31 by outputting switching control signals PWMI1 and PWMI2 to inverters 14 and 31, respectively. Further, when ECU 300 receives input of fail signal FINV from inverter 14, ECU 300 outputs shutdown signal SD to inverter 14 and shuts down inverter 14. Thereby, switching elements Q1-Q6 are turned off. In this case, each of switching elements Q1 to Q6 is electrically non-conductive unless a short circuit failure occurs. By shutting down the inverter 14, failure of components included in the inverter 14 is suppressed.

  In such a hybrid vehicle 100, for example, it is assumed that the switching element Q1 has a short circuit failure. In this case, even if the switching elements Q1 to Q6 are turned off by the shutdown signal SD, a short-circuit path is formed via the switching element Q1 that is short-circuited. Specifically, this short-circuit path branches at the neutral point of motor generator MG1 via positive electrode line VL, switching element Q1 (short-circuit failure), and U-phase coil. One of the branched short-circuit paths extends from the V-phase coil to the midpoint of the V-phase arm 16 to the diode diode D3 to the positive line VL. The other branched short-circuit path extends from the W-phase coil to the intermediate point of the W-phase arm 17 to the diode D5 to the positive electrode line VL.

  When the motor generator MG1 cannot be used due to the abnormality of the inverter 14, the retreat travel using only the motor generator MG2 may be executed. In this case, since motor generator MG1 and motor generator MG2 are connected to each other via power split device PSD, motor generator MG1 also rotates as motor generator MG2 rotates. With this rotation of motor generator MG1, an induced voltage is generated in each phase coil of motor generator MG1.

  As described above, when the switching element Q1 has a short circuit failure, a short circuit path is formed even if the inverter 14 is shut down. Therefore, in such a case, when retreat travel using motor generator MG2 is executed, a short-circuit current is generated in the short-circuit path due to the induced voltage. If this short-circuit current becomes excessive, a high temperature exceeding the heat resistance temperature of the components included in the inverter 14 may occur, and further element damage may occur.

  As a technique for suppressing such an increase in short-circuit current, there is a three-phase on control. The three-phase on control is control that turns on all the switching elements in the same stage as the short-circuited switching elements when any of the switching elements in the inverter is short-circuited. For example, in the inverter 14, when the switching element Q1 has a short circuit failure, the switching elements Q1, Q3, Q5 in the same stage are turned on (electrically conductive). When all the switching elements in the same stage are turned on, the number of paths through which current flows is increased in addition to the short-circuit path. As a result, the current flowing through the short circuit path is reduced, and an increase in the short circuit current is suppressed. Note that the vehicle traveling in the three-phase on state is called three-phase on traveling.

  When the present inventors execute such three-phase ON control, if a drive signal is input to all three-phase switching elements including a short-circuited switching element, a fail signal is generated by the inverter 14. I found out. When the fail signal is generated, the inverter 14 is shut down by the ECU 300. Therefore, in this case, three-phase on control cannot be realized.

  Therefore, in hybrid vehicle 100 equipped with the load drive device according to this embodiment, when any switching element included in inverter 14 is short-circuited, other than the arm circuit including the short-circuited switching element. Among the switching elements included in the arm circuit, the drive signal is output to the switching element in the same stage as the switching element in the short-circuit state. Further, the output of the drive signal to the switching element in the short circuit state is not executed.

  The reason why such control is executed will be described next. FIG. 2 is a diagram for explaining a pattern in which a fail signal is generated by the drive circuit 40. In particular, attention is paid to the drive circuit 40 connected to the switching element Q1 among the switching elements Q1 to Q6 included in the inverter 14. FIG.

  Referring to FIG. 2, drive circuit 40 is connected to the gate terminal of switching element Q <b> 1 and drive power supply 41. When the switching control signal PWMI1 output from the ECU 300 is input, the drive circuit 40 applies the drive voltage (15V) of the drive power supply 41 to the gate terminal of the switching element Q1. That is, the drive circuit 40 outputs a drive signal to the gate terminal of the switching element Q1 when the switching control signal PWMI1 is input. Thereby, electrical connection is established between the collector and emitter of the switching element Q1.

  A resistor R1 is provided between the drive circuit 40 and the switching element Q1. A current (for example, 1/6000) much smaller than the current flowing between the collector and the emitter of the switching element Q1 flows through the resistor R1. The drive circuit 40 can estimate the magnitude of the current flowing between the collector and the emitter of the switching element Q1 by detecting the magnitude of the current flowing through the resistor R1.

  The fail signal FINV is generated by the drive circuit 40 in at least the following two cases. First, the fail signal FINV is output by the drive circuit 40 when the current flowing through the resistor R1 increases more than a predetermined value. This is because when the current flowing through the resistor R1 increases more than a predetermined value, there is a high possibility that a short circuit has occurred between the collector and the emitter of the switching element Q1. Second, the fail signal FINV is output by the drive circuit 40 when the voltage value of the drive power supply 41 is lower than a predetermined value. This is because when the voltage value of the drive power supply 41 is lower than a predetermined value, there is a high possibility that some abnormality has occurred in the inverter 14.

  Here, when the collector-emitter of the switching element Q1 is short-circuited, the switching element Q1 does not already function as a semiconductor, and the gate-emitter is also short-circuited. When the drive voltage of the drive power supply 41 is applied to the gate terminal of the switching element Q1 in such a short circuit state, the potential of the drive power supply 41 is lowered and the voltage of the drive power supply 41 is lowered. As a result, when the voltage of the drive power supply 41 falls below a predetermined level, the drive circuit 40 outputs the fail signal FINV as described above. When fail signal FINV is output, ECU 300 shuts down inverter 14.

  That is, when the three-phase ON control is executed, if a drive signal is input to the short-circuited switching element, the drive voltage of the drive power supply 41 is lowered below a predetermined value, so that the fail signal FINV is generated. As a result, the inverter 14 is shut down, and three-phase on control cannot be realized.

  Therefore, in hybrid vehicle 100 equipped with the load driving device according to this embodiment, among the switching elements included in the arm circuit other than the arm circuit including the short-circuited switching element, the same stage as the short-circuited switching element. The drive signal is output to the switching element. Further, the output of the drive signal to the switching element in the short circuit state is not executed.

  As a result, when a short circuit occurs in the switching element included in the inverter 14, no drive signal is input to the switching element in the short circuit state, so the fail signal FINV is not generated and the inverter 14 is not shut down. As a result, three-phase on control can be realized. Next, the transition operation to three-phase on running when the switching element is short-circuited will be described.

(Transition to three-phase on-travel)
FIG. 3 is a flowchart showing the transition operation to the three-phase on running when the switching element is short-circuited. Referring to FIG. 3, when hybrid vehicle 100 is performing a normal travel that is not a three-phase on-travel, ECU 300 determines whether or not there is input of fail signal FINV (step S100). For example, when any of the switching elements included in inverter 14 is short-circuited, fail signal FINV is input to ECU 300. If it is determined that fail signal FINV is not input (NO in step S100), the process proceeds to step S140.

  On the other hand, when it is determined that there is an input of fail signal FINV (YES in step S100), ECU 300 outputs shutdown signal SD to inverters 14 and 31, and shuts down inverters 14 and 31 (step S110).

  When inverters 14 and 31 are shut down, ECU 300 identifies a short-circuited switching element included in inverter 14 (step S120). As a method for specifying the switching element in the short-circuit state, various known methods can be used. As an example, ECU 300 detects a current of each phase between inverter 14 and motor generator MG1 by a current sensor (not shown), and identifies a short-circuited switching element based on the detected current value of each phase. Specifically, ECU 300 detects an offset value from the steady operation for each phase current waveform, and detects a short-circuited switching element based on the detected magnitude and polarity of the offset value.

  When a short-circuited switching element is identified, ECU 300 does not input a drive signal to the short-circuited switching element, and inputs a drive signal to a switching element in the same stage as the short-circuited switching element. The three-phase ON control signal Ton to be output is output to the inverter 14 (step S130). As a result, among the switching elements at the same stage as the short-circuited switching element, the drive signal is input to the switching elements other than the short-circuited switching element, and the switching element to which the drive signal is input is electrically conductive. .

  Here, as an example, the case where any of the switching elements included in the inverter 14 is short-circuited has been described, but the same operation is performed when any of the switching elements included in the inverter 31 is short-circuited.

  Thus, in this hybrid vehicle 100, when any one of the switching elements included in inverters 14 and 31 is short-circuited, among the switching elements included in the arm circuit other than the arm circuit including the short-circuited switching element. The output of the drive signal to the switching element in the same stage as the switching element in the short circuit state is executed, and the output of the drive signal to the switching element in the short circuit state is not executed. According to such a configuration, since a drive signal is not input to the switching element in the short-circuit state, a fail signal is not generated, and the inverters 14 and 31 are not shut down again. As a result, three-phase on control can be realized.

  In this embodiment, the power supplied from the DC power supply 140 is directly supplied to the inverters 14 and 31, but is not necessarily limited to such a configuration. For example, a boost converter may be arranged between DC power supply 140 and inverters 14 and 31. In this case, the boost converter converts the voltage supplied to the inverters 14 and 31 to a voltage higher than the voltage of the DC power supply 140.

  In this embodiment, a series / parallel type hybrid vehicle has been described in which the power of engine ENG can be divided and transmitted to wheels and motor generator MG1 by power split device PSD. However, the technique disclosed here is not necessarily limited to application to such an example. For example, the technology disclosed herein can be applied to other types of hybrid vehicles. For example, the engine ENG is used only to drive the motor generator MG1, and the driving power of the vehicle is generated only by the motor generator MG2, or a so-called series-type hybrid vehicle, or only regenerative energy among the kinetic energy generated by the engine is electric. The technology disclosed herein can also be applied to a hybrid vehicle that is recovered as energy, a motor-assisted hybrid vehicle in which a motor assists the engine as the main power if necessary.

  Further, the technology disclosed herein can be applied to all electric vehicles such as an electric vehicle that does not include the engine ENG and runs only with electric power, and a fuel cell vehicle that further includes a fuel cell as a power source.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  14,31 Inverter, 15 U-phase arm, 16 V-phase arm, 17 W-phase arm, 18-20 conductive wire, 40 drive circuit, 41 drive power supply, 100 hybrid vehicle, 140 DC power supply, 300 ECU, C2 smoothing capacitor, D1-D6 diode, ENG engine, MG1, MG2 motor generator, PSD power split device, Q1-Q6 switching element, SL negative line, VL positive line, R1 resistance.

Claims (1)

A three-phase inverter,
A control device that controls the three-phase inverter so that the three-phase inverter is shut down by inputting a fail signal;
The fail signal is generated by inputting a drive signal to a short-circuited switching element among the upper and lower switching elements provided in the arm circuit of each phase of the three-phase inverter,
The control device includes:
Identify the switching element in the short-circuit state,
Output of drive signals to the switching elements in the same stage as the identified short-circuited switching element among the upper-stage and lower-stage switching elements included in the arm circuit other than the arm circuit including the identified short-circuited switching element And the three-phase inverter is controlled so as not to execute the output of the drive signal to the specified short-circuited switching element.

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