JP2013055821A - Power apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To electrically discharge a smoothing capacitor satisfactorily while protecting a plurality of transistors of inverters more appropriately.SOLUTION: When a smoothing capacitor 57 is electrically discharged, a hybrid ECU 70 turns off a system main relay SMR, and a motor ECU 40 turns off all the transistors other than a pair of upper and lower arm transistors including one of a plurality of transistors T11-T16, T21-T26 of inverters 41, 42 which has the lowest temperature, and turns on either of the pair of upper and lower arm transistors and switches the other at a predetermined period.

Description

  The present invention relates to an electric device, an inverter including a plurality of upper arm transistors and a plurality of lower arm transistors connected in series to the corresponding upper arm transistors, and a battery capable of exchanging electric power with the electric device via the inverter, The present invention relates to a power device including a smoothing capacitor that smoothes a voltage between an inverter and a battery.

  Conventionally, as this type of power device, a smoothing capacitor connected to a DC power source, an inverter circuit including a plurality of pairs of switching elements respectively connected to a positive terminal and a negative terminal of the smoothing capacitor, and the inverter circuit are controlled When discharging the electric charge stored in the smoothing capacitor, one of the pair of switching elements of the inverter circuit is held in the energized state and the other is repeatedly turned on and off. For example, Japanese Patent Application Laid-Open No. H10-228707 proposes discharge control for switching operation. In this power device, regardless of whether or not an electric device (for example, an electric motor) that can consume power is connected to the device, the above-described discharge control generates a saturation current that flows between the smoothing capacitor and the switching element. By doing so, the electric charge stored in the smoothing capacitor can be discharged.

JP 2010-233310 A

  However, when discharging control is performed using any switching element of the inverter circuit when discharging the electric charge stored in the smoothing capacitor as in the above-described power device, a pair of switching elements used for the discharge control There is a risk that the temperature of this will rise excessively.

  The main purpose of the power device of the present invention is to satisfactorily discharge the electric charge stored in the smoothing capacitor while more appropriately protecting the plurality of transistors of the inverter.

  The power device of the present invention employs the following means in order to achieve the main object described above.

The power device of the present invention is
An electric device, an inverter including a plurality of upper arm transistors and a plurality of lower arm transistors connected in series to the corresponding upper arm transistors, and a battery capable of exchanging electric power with the electric device via the inverter, A smoothing capacitor for smoothing a voltage between the inverter and the battery; a relay capable of executing connection / disconnection of the battery and the smoothing capacitor; relay control means for controlling the relay; and the inverter In an electric power device comprising an inverter control means for controlling
The relay control means turns off the relay when the charge stored in the smoothing capacitor is to be discharged,
When the inverter control means is to discharge the charge stored in the smoothing capacitor, the inverter control means includes a pair of the upper arm transistor and the lower arm transistor other than the pair of the upper arm transistor and the lower arm transistor including the one having the lowest temperature. All of the transistors are turned off, one of the pair of upper arm transistors and lower arm transistors is turned on, and the other is switched at a predetermined cycle.

  In the power device of the present invention, when the electric charge stored in the smoothing capacitor is to be discharged, the relay between the battery and the smoothing capacitor is turned off, and the temperature is the highest among the plurality of upper arm transistors and lower arm transistors of the inverter. All of the transistors other than the pair of upper arm transistor and lower arm transistor including the low one are turned off, and either one of the pair of upper arm transistor or lower arm transistor is turned on and the other is switched at a predetermined cycle. Thereby, when the electric charge stored in the smoothing capacitor is to be discharged, the current from the smoothing capacitor flows only to the pair of upper arm transistor and lower arm transistor including the lowest temperature among the plurality of transistors of the inverter. The temperature of the plurality of transistors can be prevented from excessively increasing. Therefore, according to the power device of the present invention, it is possible to favorably discharge the charge stored in the smoothing capacitor due to the switching loss of the transistors while protecting the plurality of transistors more appropriately.

1 is a schematic configuration diagram of a hybrid vehicle 20 having a power device according to an embodiment of the present invention. 2 is a schematic configuration diagram of an electric drive system mounted on a hybrid vehicle 20. FIG. 3 is a flowchart illustrating an example of a discharge control routine that is executed by a motor ECU after a vehicle collision is detected in the hybrid vehicle according to the embodiment.

  Next, the form for implementing this invention is demonstrated using an Example.

  FIG. 1 is a schematic configuration diagram of a hybrid vehicle 20 having a power device according to an embodiment of the present invention. The hybrid vehicle 20 of the embodiment includes an engine 22 that uses gasoline or light oil as fuel, an engine electronic control unit (hereinafter referred to as engine ECU) 24 that controls the drive of the engine 22, and a crankshaft as an output shaft of the engine 22. A planetary gear 30 having a carrier 34 connected to a damper 26 via a damper 28, a motor MG1 capable of generating electricity connected to a sun gear 31 of the planetary gear 30, and a ring gear shaft 32a as a drive shaft connected to the ring gear 32 of the planetary gear 30. The reduction gear 35 is connected, the motor MG2 is connected to the reduction gear 35, and the drive wheels 39a and 39b are connected to the ring gear shaft 32a via a gear mechanism 37 and a differential gear 38.

  Further, the hybrid vehicle 20 is connected between the motor MG 1 and the power line 54, such as a battery 50 that is a lithium ion secondary battery or a nickel hydride secondary battery connected to the power line 54 via the system main relay SMR. The inverter 41 provided, the inverter 42 interposed between the motor MG2 and the power line 54, and the inverter 41 connected to the power line 54 so as to be located closer to the inverters 41 and 42 than the system main relay SMR. , 42 and the battery 50, a smoothing capacitor 57 for smoothing the voltage, and a motor electronic control unit (hereinafter referred to as “motor ECU”) 40 for driving and controlling the motors MG1 and MG2 via the inverters 41, 42, , A battery electronic control unit (hereinafter referred to as a battery) that manages the battery 50 It includes an ECU hereinafter) 52, an engine ECU24, the motor ECU 40, the hybrid electronic control unit that controls the entire vehicle while communicating with the battery ECU52 like (hereinafter, referred to as hybrid ECU) and 70.

  Each of the motor MG1 and the motor MG2 is configured as a known synchronous generator motor including a rotor in which a permanent magnet is embedded and a stator around which a three-phase coil is wound. As shown in FIG. 2, the inverters 41 and 42 include six transistors T11 to T16 and T21 to T26, and six diodes D11 to D16 and D21 connected in parallel to the transistors T11 to T16 and T21 to T26 in the reverse direction. D26. Two transistors T11 to T16 and T21 to T26 of the inverters 41 and 42 are provided so that they are on the source side and the sink side with respect to the positive electrode bus 54a and the negative electrode bus 54b that the inverters 41 and 42 share as the power line 54, respectively. Each of the three-phase coils (U-phase, V-phase, W-phase) of the motors MG1, MG2 is connected to each connection point between the paired transistors. Therefore, a rotating magnetic field is formed in the three-phase coil by controlling the ratio of the on-time of the transistors T11 to T16 and T21 to T26 that make a pair while a voltage is acting between the positive electrode bus 54a and the negative electrode bus 54b. The motors MG1, MG2 can be driven to rotate. The inverters 41 and 42 are provided with temperature sensors S11 to S16 and S21 to S26 for detecting the temperatures of the transistors T11 to T16 and T21 to T26, respectively. Hereinafter, the three transistors T11 to T13 of the inverter 41 and the three transistors T21 to T23 of the inverter 42 are referred to as “upper arm transistors” and are respectively connected in series to corresponding ones of the upper arm transistors T11 to T13. The three transistors T14 to T16 of the inverter 41 connected to the inverter 41 and the three transistors T24 to T26 of the inverter 42 connected in series to the corresponding one of the upper arm transistors T21 to T23, respectively. It is called “arm transistor”.

  Inverters 41 and 42 are controlled by motor ECU 40, thereby driving and controlling motors MG 1 and MG 2. The motor ECU 40 receives signals necessary for driving and controlling the motors MG1 and MG2, such as signals from rotational position detection sensors 43 and 44 for detecting the rotational positions of the rotors of the motors MG1 and MG2, and transistors T11 to T16 and T21. The transistor temperatures Ttr11 to 16 and Ttr21 to 26 from the temperature sensors S11 to S16 and S21 to S26 that respectively detect the temperatures of T26 to T26, the voltage VH from the voltage sensor 57a that detects the voltage of the smoothing capacitor 57, and the like are input. Further, the motor ECU 40 outputs switching control signals to the transistors T11 to T16 and T21 to T26 of the inverters 41 and 42. The motor ECU 40 is in communication with the hybrid ECU 70, controls the driving of the motors MG1 and MG2 by a control signal from the hybrid ECU 70, and outputs data related to the operating state of the motors MG1 and MG2 to the hybrid ECU 70 as necessary. The motor ECU 40 also calculates the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 based on signals from the rotational position detection sensors 43 and 44.

  When the ignition switch 80 is turned on in the hybrid vehicle 20 of the embodiment configured as described above, the hybrid ECU 70 detects the accelerator opening degree Acc and the vehicle speed sensor from the accelerator pedal position sensor 84 that detects the depression amount of the accelerator pedal 83. The required torque Tr * is set based on the vehicle speed V from 88, and the target rotational speed Ne *, the target torque Te * of the engine 22 and the torque commands Tm1 * of the motors MG1, MG2 are set based on the set required torque Tr *. Command signals such as Tm2 * are generated, and the generated command signals are transmitted to the engine ECU 24 and the motor ECU 40. Further, the acceleration of the vehicle is input to the hybrid ECU 70 from an acceleration sensor 58 serving as a collision detection unit attached to a vehicle body (for example, a central portion or both side portions in front of the vehicle). The hybrid ECU 70 determines that a vehicle collision has occurred, for example, when the input acceleration exceeds a threshold value for collision determination or a threshold value for operating a safety device such as an airbag. In order to improve safety, the system main relay SMR is turned off to disconnect the battery 50 from the electric system of the vehicle, and a predetermined collision occurrence signal is transmitted to each ECU 24, 40, 52 and the like.

  In such a hybrid vehicle 20, when a collision occurs, the charge stored in the smoothing capacitor 57 must be discharged quickly in order to reduce the gate voltage of the inverters 41 and 42 at an early stage. Therefore, when the motor ECU 40 of the embodiment receives the collision occurrence signal from the hybrid ECU 70 and the discharge of the electric charge stored in the smoothing capacitor 57 is not completed, a discharge control routine shown in FIG. 3 is executed. Whether or not the discharge of the electric charge stored in the smoothing capacitor 57 has been completed depends on whether or not the voltage VH that is the voltage across the smoothing capacitor 57 detected by the voltage sensor 57a is equal to or lower than a predetermined threshold value. Judgment based on.

  When the execution of the discharge control routine is started, the motor ECU 40 of the embodiment first inputs the values of the transistor temperatures Ttr11 to 16 and Ttr21 to 26 from the temperature sensors S11 to S16 and S21 to S26. Based on the values of Ttr11 to Ttr16 and Ttr21 to Ttr26, it is determined which of the transistors T11 to T16 and T21 to T26 has the lowest temperature (step S100). If the transistor having the lowest temperature is determined in step S100, discharge control is performed for a predetermined time tref using the pair of upper arm transistor and lower arm transistor including the transistor having the lowest temperature (step S110). Here, specifically, in the discharge control, if it is determined in step S100 that the temperature Ttr14 of the lower arm transistor T14 is the lowest, the upper arm connected in series to the lower arm transistor T14 and the lower arm transistor T14. All the transistors other than the arm transistor T11 are turned off, the upper arm transistor T11 is turned on, and the lower arm transistor T14 is controlled to be switched at a predetermined cycle. Thus, when the lower arm transistor T14 is turned on, current flows from the smoothing capacitor 57 to the upper arm transistor T11 and the lower arm transistor T14 of the inverter 41, and smoothing is performed using the switching loss generated in the lower arm transistor T14. It becomes possible to quickly discharge the electric charge stored in the capacitor 57. However, in the discharge control, the lower arm transistor T14 may be turned on and the upper arm transistor T11 may be switched in a predetermined cycle. Note that the predetermined period is determined as a value that allows the charge stored in the smoothing capacitor 57 to be discharged within a predetermined discharge time by switching control of the upper arm transistor or the lower arm transistor in the period. The predetermined time tref is determined as a time longer than at least the predetermined period.

  Subsequently, the motor ECU 40 determines whether or not the discharge of the electric charge stored in the smoothing capacitor 57 has been completed (step S120). In the embodiment, as described above, the discharge of the charge stored in the smoothing capacitor 57 is completed when the voltage VH, which is the voltage between the terminals of the smoothing capacitor 57 detected by the voltage sensor 57a, is equal to or lower than a predetermined threshold value. Judge. And when it determines with discharge of the electric charge stored in the smoothing capacitor 57 not having been completed in step S120, the process of step S100 and S110 is performed again. That is, it is determined again which of the transistors T11 to T16, T21 to T26 is the lowest temperature, and the discharge control is performed for a predetermined time tref using a pair of upper arm transistor and lower arm transistor including the transistor having the lowest temperature. Continue. In this way, a pair of upper arm transistor and lower arm transistor including the transistor having the lowest temperature among the transistors T11 to T16 and T21 to T26 of the inverters 41 and 42 are selected at intervals (every predetermined time tref). When the discharge control is executed so that the current from the smoothing capacitor flows only in the pair of upper arm transistor and lower arm transistor, the temperature of each of the transistors T11 to T16 and T21 to T26 is excessively increased. Since it can be suppressed, the transistors T11 to T16 and T21 to T26 can be protected.

  On the other hand, when it is determined in step S120 that the discharge of the charge stored in smoothing capacitor 57 has been completed, motor ECU 40 shuts down inverters 41 and 42 (step S130), and ends this routine. Note that the determination of whether or not the discharge of the electric charge stored in the smoothing capacitor 57 in step S120 has been completed may be performed at all times during the execution of the processes in steps S100 and S110. When the discharge of the electric charge stored in the smoothing capacitor 57 is completed during the processing of S100 and S110, the inverters 41 and 42 are immediately shut down (step S130), and this routine may be terminated. .

  In the hybrid vehicle 20 equipped with the power device according to the embodiment described above, when a collision occurs in the hybrid vehicle 20, that is, when the charge stored in the smoothing capacitor 57 should be discharged, the hybrid ECU 70 and the The system main relay SMR to and from the capacitor 57 is turned off, and the motor ECU 40 causes a pair of upper arm transistors and lower arms including the lowest temperature among the plurality of transistors T11 to T16 and T21 to T26 of the inverters 41 and 42. All the transistors other than the transistors are turned off, one of the pair of upper arm transistors and lower arm transistors is turned on, and the other is switched at a predetermined cycle. Thereby, when the electric charge stored in the smoothing capacitor 57 is to be discharged, a pair of upper arm transistor and lower arm transistor including the lowest temperature among the plurality of transistors T11 to T16 and T21 to T26 of the inverters 41 and 42. Only the current from the smoothing capacitor 57 flows. In addition, until the discharge of the smoothing capacitor 57 is completed, the temperature of at least one of the pair of upper arm transistors and lower arm transistors used for discharging the smoothing capacitor 57 increases, and the other pair of upper arm transistors and lower arm transistors When the transistor having the lowest temperature is included, the discharge control of the smoothing capacitor 57 using the other pair of upper arm transistor and lower arm transistor is executed. Thereby, the temperature of the plurality of transistors T11 to T16, T21 to T26 can be prevented from being excessively increased. Therefore, according to the hybrid vehicle 20 equipped with the power device according to the embodiment, the charge stored in the smoothing capacitor 57 due to the switching loss of the transistors is more appropriately protected while protecting the plurality of transistors T11 to T16 and T21 to T26 more appropriately. It becomes possible to discharge well.

  In this embodiment, when a collision occurs in the hybrid vehicle 20, the motor ECU 40 executes the discharge control routine to discharge the electric charge stored in the smoothing capacitor 57. The motor ECU 40 may execute the discharge control routine when the charge stored in the smoothing capacitor 57 should be discharged for some reason. Further, the power device of the present invention is not limited to the one mounted on the hybrid vehicle 20 of the embodiment having the inverters 41 and 42 that drive the motors MG1 and MG2, but a single motor and a single motor that drives the motor You may mount in the other hybrid vehicle which has an inverter, an electric vehicle, etc.

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problems will be described. In the embodiment, the motors MG1 and MG2 correspond to “electrical devices”, and a plurality of upper arm transistors T11 to T13 and T21 to T23 and a plurality of upper arm transistors T11 to T13 and T21 to T23 respectively connected in series. The inverters 41 and 42 including the lower arm transistors T14 to T16 and T24 to T26 correspond to “inverters”, and the battery 50 that can exchange power with the motors MG1 and MG2 via the inverters 41 and 42 is “battery”. The smoothing capacitor 57 that smoothes the voltage between the inverters 41 and 42 and the battery 50 corresponds to a “smoothing capacitor”, and is a system that can execute connection and release of the battery 50 and the smoothing capacitor 57. Relay SMR corresponds to “relay”, and system main relay SMR Hybrid ECU70 for controlling corresponds to the "relay control unit", the motor ECU40 for controlling the inverters 41 and 42 corresponds to the "inverter control unit".

  The correspondence between the main elements of the embodiment and the main elements of the invention described in the column of means for solving the problem is the same as that of the embodiment described in the column of means for solving the problem. Therefore, the elements of the invention described in the column of means for solving the problems are not limited. That is, the interpretation of the invention described in the column of means for solving the problems should be made based on the description of the column, and the examples are those of the invention described in the column of means for solving the problems. It is only a specific example.

  As mentioned above, although the form for implementing this invention was demonstrated using the Example, this invention is not limited at all to such an Example, In the range which does not deviate from the summary of this invention, it is with various forms. Of course, it can be implemented.

  The present invention is applicable to the power device manufacturing industry.

  20 hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 26 crankshaft, 28 damper, 30 planetary gear, 31 sun gear, 32 ring gear, 32a ring gear shaft, 34 carrier, 35 reduction gear, 37 gear mechanism, 38 Differential gear, 39a, 39b Drive wheel, 40 Motor electronic control unit (motor ECU), 41, 42 Inverter, 43, 44 Rotation position detection sensor, 50 Battery, 52 Battery electronic control unit (battery ECU), 54 Power line , 54a positive bus, 54b negative bus, 57 smoothing capacitor, 57a voltage sensor, 58 acceleration sensor, 70 electronic control unit for hybrid (hybrid ECU), 83 accelerator pedal, 84 Accelerator pedal position sensor, 88 vehicle speed sensor, D11-D16, D21-D26 diode, MG1, MG2 motor, S11-S16, S21-S26 temperature sensor, SMR system main relay, T11-T16, T21-T26 transistor.

Claims (1)

An electric device, an inverter including a plurality of upper arm transistors and a plurality of lower arm transistors connected in series to the corresponding upper arm transistors, and a battery capable of exchanging electric power with the electric device via the inverter, A smoothing capacitor for smoothing a voltage between the inverter and the battery; a relay capable of executing connection / disconnection of the battery and the smoothing capacitor; relay control means for controlling the relay; and the inverter In an electric power device comprising an inverter control means for controlling
The relay control means turns off the relay when the charge stored in the smoothing capacitor is to be discharged,
When the inverter control means is to discharge the charge stored in the smoothing capacitor, the inverter control means includes a pair of the upper arm transistor and the lower arm transistor other than the pair of the upper arm transistor and the lower arm transistor including the one having the lowest temperature. A power device comprising: turning off all of the transistors; turning on one of the pair of upper arm transistors and lower arm transistors; and switching the other with a predetermined period.

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