JP2008312306A - Vehicle and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve evacuation traveling while protecting in-vehicle equipment when an OFF-failure of an upper arm of a step-up/step-down converter occurs. <P>SOLUTION: When a voltage VH detected by a VH voltage sensor exceeds an overvoltage threshold within a prescribed period of time (Yes in a step S120), the number of times of exceeding the overvoltage threshold is counted by an overvoltage history counter (a step S210). When the counted counter value exceeds a prescribed value (Yes in a step S260), it is considered that a trouble occurs in step-down operation of a step-up/step-down converter, and the step-up/step-down converter and an inverter are controlled so that a motor is operated by battery power in a state of inhibiting battery charging by the motor (steps S270-S290, S180-S200). By this, an overvoltage is eliminated so as to allow self-traveling by driving the motor with battery power. Accordingly, it is possible to ensure evacuation traveling while protecting in-vehicle equipment from an overvoltage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a vehicle and a control method thereof.

Conventionally, a vehicle including a step-up / down converter and an electric motor has been proposed. Here, the step-up / step-down converter is composed of a chopper circuit having switching elements called an upper arm and a lower arm. The lower arm is turned on to input low-voltage power of the battery and boost it to high-voltage power. Or the upper arm is turned on and high voltage power generated by the regenerative operation of the motor is input, and the voltage is stepped down to low voltage power and output to the battery. For example, in the vehicle of Patent Document 1, the low voltage VL on the battery side of the buck-boost converter and the high voltage VH on the motor side are detected, and the absolute value of the difference between the low voltage VL and the high voltage VH is less than a constant A and is high. When the voltage VH is less than the constant B, it is assumed that an on-failure of the upper arm of the buck-boost converter can be detected because the boost operation of the buck-boost converter is hindered.
JP 2007-68305 A

  However, in the above-described vehicle, although an on failure of the upper arm of the buck-boost converter can be detected, an off failure is not considered. When the upper arm of the buck-boost converter fails during regenerative operation of the motor, high voltage power is input and the voltage is stepped down to low voltage power and cannot be supplied to the battery. Overvoltage exceeds a predetermined threshold. Here, it is conceivable that the gate of the switching element of the inverter or the buck-boost converter is shut off whenever the overvoltage is reached, and the gate is allowed when the voltage drops to a normal value. Not good for. In addition, it is conceivable to protect the in-vehicle device by prohibiting the vehicle from traveling immediately when an overvoltage occurs, but it is preferable that the vehicle can be evacuated at a minimum.

  The main purpose of the vehicle and the control method thereof according to the present invention is to enable retreat travel while protecting the in-vehicle device when an off failure of the upper arm of the buck-boost converter occurs.

  The vehicle and the control method thereof according to the present invention employ the following means in order to achieve at least a part of the above-described object.

The vehicle of the present invention
A high-voltage motor that can input and output power to the axle;
Low-voltage power storage means capable of exchanging electric power with the electric motor with charging and discharging;
A high voltage that is provided between the electric motor and the electric storage means, inputs low-voltage electric power on the electric storage means side, boosts the electric power to high-voltage electric power, outputs the electric power to the electric motor side, or is generated by regenerative operation of the electric motor A step-up / step-down converter that inputs the electric power of the current and lowers the electric power to a low-voltage electric power and outputs it to the power storage means side;
When the voltage on the motor side of the buck-boost converter exceeds a predetermined threshold value, the buck-boost converter and the motor are controlled so that the voltage recovers below the threshold value. When the number of times that the voltage on the motor side exceeds the threshold value within a predetermined period is less than a predetermined reference number, power is transferred between the motor and the power storage means after the voltage recovers below the threshold value. The step-up / down converter and the electric motor are controlled so as to be exchanged, and when the number of times that the voltage on the motor side of the step-up / down converter exceeds the threshold value within a predetermined period is greater than or equal to a predetermined reference number, the electric motor The step-up / step-down converter and the electric motor so that the electric motor is operated by the electric power of the electric storage means with the discharging of the electric storage means in a state where charging of the electric storage means is prohibited And control means for controlling,
It is a summary to provide.

  In the vehicle according to the present invention, when the voltage on the motor side of the step-up / step-down converter exceeds a predetermined threshold value, the step-up / step-down converter and the electric motor are controlled so that the voltage recovers below the threshold value. On the other hand, if the number of times the voltage on the motor side of the buck-boost converter exceeds the threshold value within a predetermined period is less than the predetermined reference number, the buck-boost converter is considered normal and the voltage recovers below the threshold value. After that, the buck-boost converter and the electric motor are controlled so that electric power is exchanged between the electric motor and the power storage means. As a result, the electric motor can be driven by the electric power of the power storage means, and the regenerative power of the motor can be stored in the power storage means. On the other hand, when the number of times the voltage on the motor side of the step-up / down converter exceeds the threshold value within a predetermined period is equal to or greater than a predetermined reference number, it is considered that the step-down operation of the step-up / down converter is hindered. The step-up / step-down converter and the electric motor are controlled so that the electric motor is operated by the electric power of the electric storage means accompanied by the discharge of the electric storage means in a state where charging of the electric storage means is prohibited. Here, when trouble occurs in the step-down operation of the buck-boost converter, the regenerative current of the motor cannot flow to the power storage means, and the motor side of the buck-boost converter tends to be overvoltage due to the regenerative power without a place to go. Then, the electric motor is operated by the electric power of the electric storage means in a state where charging of the electric storage means by the electric motor is prohibited. Thereby, the overvoltage on the electric motor side of the step-up / down converter is eliminated, and the electric motor can be driven by the electric power of the power storage means to be able to run on its own. Therefore, even when the step-down operation of the step-up / step-down converter is hindered, retreat travel can be secured while protecting the in-vehicle device from overvoltage.

  In such a vehicle of the present invention, the step-up / step-down converter is connected between the positive terminal of the power storage means and the electric motor, and turns on and off the current flow from the electric motor to the positive terminal. A second switching element connected between an intermediate point between the one switching element and the positive electrode terminal and a negative electrode terminal of the power storage means and turning on and off a current flow from the intermediate point to the negative electrode terminal; A reactor connected between the positive terminal, a first diode connected in parallel with the first switching element and allowing only a current flow from the intermediate point to the motor, and in parallel with the second switching element And a second diode that allows only a current flow from the negative terminal to the intermediate point, and that turns on both switching elements at a predetermined cycle. By adjusting the time, the low voltage power on the power storage means side is input and boosted to the high voltage power and output to the motor side, or the high voltage power generated by the regenerative operation of the motor is input and low The control means reduces the voltage power to the power storage means side, and the control means outputs a predetermined number of times that the high voltage output to the motor side exceeds the threshold value within a predetermined period. When the number of times is equal to or greater than the reference number, the current flow of both the switching elements of the buck-boost converter may be turned off. In this way, the low voltage power on the power storage means side can be input to the buck-boost converter and output to the motor side via the first diode without being boosted as it is.

  The vehicle of the present invention further includes a smoothing capacitor that is connected in parallel to the electric motor as viewed from the step-up / down converter and smoothes a high voltage on the electric motor side of the step-up / down converter, and the control means includes a terminal of the smoothing capacitor. The inter-voltage may be input as a high voltage output to the electric motor side. The electric motor may be supplied with electric power through an inverter circuit that converts direct-current power output from the step-up / down converter to alternating-current power.

  Further, in the vehicle of the present invention, an internal combustion engine capable of inputting / outputting power to / from the axle, and the electric motor as viewed from the electric storage means, are connected in parallel with the electric storage means, and can exchange electric power with the electric storage means, and from the internal combustion engine A high-voltage generator capable of generating power using motive power, and the control means, when the voltage on the motor side of the buck-boost converter exceeds a predetermined threshold, the voltage is the threshold While controlling the buck-boost converter, the motor, the generator, and the internal combustion engine to recover to the following, the number of times that the voltage on the motor side of the buck-boost converter exceeded the threshold value within a predetermined period When the voltage is less than a predetermined reference number, the voltage is restored to the threshold value or less, and power is exchanged between the electric motor and the power storage means. The generator and the internal combustion engine are controlled, and when the number of times that the voltage on the motor side of the buck-boost converter exceeds the threshold value within a predetermined period is a predetermined reference number or more, the generator and the motor Controlling the step-up / down converter, the electric motor, the generator, and the internal combustion engine so that the electric motor is operated by the electric power of the electric storage means with discharging of the electric storage means in a state where charging of the electric storage means is prohibited It is good.

The vehicle control method of the present invention includes a high voltage electric motor capable of inputting / outputting power to / from an axle, a low voltage electric storage means capable of exchanging electric power with the electric motor with charge / discharge, the electric motor and the electric storage. The low voltage power on the power storage means side is input and boosted to the high voltage power and output to the motor side, or the high voltage power generated by the regenerative operation of the motor is input. A control method for a vehicle comprising: a step-up / down converter that steps down to low voltage power and outputs it to the power storage means side;
When the voltage on the motor side of the buck-boost converter exceeds a predetermined threshold value, the buck-boost converter and the motor are controlled so that the voltage recovers below the threshold value. When the number of times that the voltage on the motor side exceeds the threshold value within a predetermined period is less than a predetermined reference number, power is transferred between the motor and the power storage means after the voltage recovers below the threshold value. The step-up / down converter and the electric motor are controlled so as to be exchanged, and when the number of times that the voltage on the motor side of the step-up / down converter exceeds the threshold value within a predetermined period is greater than or equal to a predetermined reference number, the electric motor The step-up / step-down converter and the electric motor so that the electric motor is operated by the electric power of the electric storage means with the discharging of the electric storage means in a state where charging of the electric storage means is prohibited To control,
This is the gist.

  In the vehicle control method of the present invention, when the voltage on the motor side of the step-up / step-down converter exceeds a predetermined threshold value, the step-up / step-down converter and the electric motor are controlled so that the voltage recovers below the threshold value. On the other hand, if the number of times the voltage on the motor side of the buck-boost converter exceeds the threshold value within a predetermined period is less than the predetermined reference number, the buck-boost converter is considered normal and the voltage recovers below the threshold value. After that, the buck-boost converter and the electric motor are controlled so that electric power is exchanged between the electric motor and the power storage means. As a result, the electric motor can be driven by the electric power of the power storage means, and the regenerative power of the motor can be stored in the power storage means. On the other hand, when the number of times the voltage on the motor side of the step-up / down converter exceeds the threshold value within a predetermined period is equal to or greater than a predetermined reference number, it is considered that the step-down operation of the step-up / down converter is hindered. The step-up / step-down converter and the electric motor are controlled so that the electric motor is operated by the electric power of the electric storage means accompanied by the discharge of the electric storage means in a state where charging of the electric storage means is prohibited. Here, when trouble occurs in the step-down operation of the buck-boost converter, the regenerative current of the motor cannot flow to the power storage means, and the motor side of the buck-boost converter tends to be overvoltage due to the regenerative power without a place to go. Then, the electric motor is operated by the electric power of the electric storage means in a state where charging of the electric storage means by the electric motor is prohibited. Thereby, the overvoltage on the electric motor side of the step-up / down converter is eliminated, and the electric motor can be driven by the electric power of the power storage means to be able to run on its own. Therefore, even when the step-down operation of the step-up / step-down converter is hindered, retreat travel can be secured while protecting the in-vehicle device from overvoltage. In this vehicle control method, a step for realizing any of the functions of the vehicle described above may be added.

  Next, the best mode for carrying out the present invention will be described using examples.

  FIG. 1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20 equipped with a power supply device according to an embodiment of the present invention, and FIG. 2 is a configuration diagram showing an outline of the configuration of an electric drive system including motors MG1 and MG2. It is. As shown in FIG. 1, the hybrid vehicle 20 according to the embodiment includes an engine 22, a three-shaft power distribution and integration mechanism 30 connected to a crankshaft 26 as an output shaft of the engine 22 via a damper 28, A motor MG1 capable of generating electricity connected to the distribution integration mechanism 30, a motor MG2 connected to a ring gear shaft 32a as a drive shaft connected to the power distribution integration mechanism 30 via a reduction gear 35, and a direct current to an alternating current The inverters 41 and 42 that can be converted into the motors MG1 and MG2 and the step-up / down converter 55 that can convert the voltage of the power from the battery 50 and supply it to the inverters 41 and 42, and the entire drive system of the vehicle And a hybrid electronic control unit 70 to be controlled.

  The engine 22 is an internal combustion engine that outputs power using a hydrocarbon-based fuel such as gasoline or light oil, and an engine electronic control unit (hereinafter referred to as an engine ECU) that receives signals from various sensors that detect the operating state of the engine 22. ) 24 is under operation control such as fuel injection control, ignition control, intake air amount adjustment control. The engine ECU 24 is in communication with the hybrid electronic control unit 70, controls the operation of the engine 22 by a control signal from the hybrid electronic control unit 70, and, if necessary, transmits data related to the operating state of the engine 22 to the hybrid electronic control. Output to unit 70.

  The power distribution and integration mechanism 30 includes an external gear sun gear 31, an internal gear ring gear 32 disposed concentrically with the sun gear 31, a plurality of pinion gears 33 that mesh with the sun gear 31 and mesh with the ring gear 32, A planetary gear mechanism is provided that includes a carrier 34 that holds a plurality of pinion gears 33 so as to rotate and revolve, and that performs differential action using the sun gear 31, the ring gear 32, and the carrier 34 as rotational elements. In the power distribution and integration mechanism 30, the crankshaft 26 of the engine 22 is connected to the carrier 34, the motor MG1 is connected to the sun gear 31, and the reduction gear 35 is connected to the ring gear 32 via the ring gear shaft 32a. When functioning as a generator, power from the engine 22 input from the carrier 34 is distributed according to the gear ratio between the sun gear 31 side and the ring gear 32 side, and when the motor MG1 functions as an electric motor, the engine input from the carrier 34 The power from 22 and the power from the motor MG1 input from the sun gear 31 are integrated and output to the ring gear 32 side. The power output to the ring gear 32 is finally output from the ring gear shaft 32a to the drive wheels 63a and 63b of the vehicle via the gear mechanism 60 and the differential gear 62.

  Each of the motor MG1 and the motor MG2 includes a rotor having a permanent magnet embedded therein and a stator around which a three-phase coil is wound, and can be driven as a generator and a known synchronous generator motor that can be driven as an electric motor The power is exchanged with the battery 50 via the inverters 41 and 42. As shown in FIG. 2, the inverters 41 and 42 include six diodes (insulated gate bipolar transistors) T11 to T16 and T21 to 26 and six diodes connected in parallel to the transistors T11 to T16 and T21 to T26 in the reverse direction. It is comprised by D11-D16, D21-D26. Two transistors T11 to T16 and T21 to T26 are arranged in pairs so that each of the inverters 41 and 42 becomes a source side and a sink side with respect to the positive electrode bus 54a and the negative electrode bus 54b shared by the power line 54. 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. Since the inverters 41 and 42 share the positive electrode bus 54a and the negative electrode bus 54b, the electric power generated by one of the motors MG1 and MG2 can be supplied to another motor. Therefore, battery 50 is charged / discharged by electric power generated from one of motors MG1 and MG2 or insufficient electric power. If the balance of electric power is balanced by the motors MG1 and MG2, the battery 50 is not charged / discharged. The motors MG1 and MG2 are both driven and controlled by a motor electronic control unit (hereinafter referred to as a motor ECU) 40. 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 (see FIG. 1) for detecting the rotational positions of the rotors of the motors MG1 and MG2. Phase current applied to the motors MG1 and MG2 detected by the current sensor, voltage VL from the VL voltage sensor 92 (voltage between terminals of the capacitor 59) and voltage VH from the VH voltage sensor 93 (voltage between terminals of the capacitor 57) ) And the like, and the motor ECU 40 outputs a switching control signal to the inverters 41 and 42 and a switching control signal to the step-up / down converter 55. The motor ECU 40 is in communication with the hybrid electronic control unit 70, controls the driving of the motors MG1 and MG2 by a control signal from the hybrid electronic control unit 70, and, if necessary, data on the operating state of the motors MG1 and MG2. Output to the hybrid electronic control unit 70.

  The battery 50 is managed by a battery electronic control unit (hereinafter referred to as a battery ECU) 52. The battery ECU 52 includes signals necessary for managing the battery 50, for example, a battery voltage from a battery sensor (not shown) installed between the terminals of the battery 50, and a power line 54 connected to the input / output terminals of the battery 50. The charging / discharging current from the attached current sensor (not shown), the battery temperature Tb of the battery 50 detected by the temperature sensor 51, and the like are input, and the data on the state of the battery 50 is electronically controlled by communication as necessary. Output to unit 70. Among these, the battery voltage is used when power from the battery 50 is supplied to the motors MG1 and MG2 via the step-up / down converter 55, or when the battery 50 is charged with power stepped down from the step-up / down converter 55. The battery ECU 52 also calculates the remaining capacity (SOC) based on the integrated value of the charge / discharge current detected by the current sensor in order to manage the battery 50.

  As shown in FIG. 2, the buck-boost converter 55 is connected between the positive terminal of the battery 50 and the motors MG1 and MG2, and turns on and off the current flow from the motors MG1 and MG2 to the positive terminal of the battery 50. A current flow from the intermediate point M to the negative terminal is connected between the transistor (insulated gate bipolar transistor) T31, the intermediate point M between the first transistor T31 and the positive terminal of the battery 50, and the negative terminal of the battery 50. A second transistor (insulated gate bipolar transistor) T32 for turning on and off, a reactor L connected between the intermediate point M and the positive terminal, and a motor MG1 connected in parallel with the first transistor T31 from the intermediate point M , In parallel with the first diode D31 allowing only current flow to MG2 and the second transistor T32. And a second diode D32 which allows only the flow of current to the intermediate point M to continue to the negative terminal of the battery 50. Therefore, by controlling the switching of the transistors T31 and T32, the voltage of the DC power of the battery 50 is boosted and supplied to the inverters 41 and 42, or the DC voltage acting on the positive bus 54a and the negative bus 54b is lowered. Thus, the battery 50 can be charged. Even when the gates of the transistors T31 and T32 are cut off, the DC power of the battery 50 can be supplied to the inverters 41 and 42 through the diode D31 without increasing the voltage. A smoothing capacitor 59 is connected between the reactor L and the negative electrode bus 54b. Between the terminals of the capacitor 59, a VL voltage sensor 92 is installed, and detects the voltage VL before step-up / down of the step-up / down converter 55 (after step-down). Further, a smoothing capacitor 57 is connected between the positive electrode bus 54a and the negative electrode bus 54b. A VH sensor 93 is installed between the terminals of the capacitor 57 to detect the voltage VH after step-up (before step-down) of the step-up / down converter 55. That is, the buck-boost converter 55 basically uses the voltage values detected by the VL voltage sensor 92 and the VH voltage sensor 93 to basically exchange power between the battery 50 and the two motors MG1, MG2. In order to perform smoothing, switching control of the transistors T31 and T32 of the step-up / down converter 55 is performed so that the boosted voltage VH becomes the voltage command VH * or the lowered voltage VL becomes the voltage command VL *. It is. In addition, the power stored in the capacitor 57 can be discharged by a resistor (not shown) connected in parallel to the capacitor 57. In the following description, the transistor T31 may be referred to as “upper arm”, and the transistor T32 may be referred to as “lower arm”.

  As shown in FIG. 1, the hybrid electronic control unit 70 is configured as a microprocessor centered on a CPU 72. In addition to the CPU 72, a ROM 74 that stores a processing program, a RAM 76 that temporarily stores data, A rewritable flash memory 78 that stores information on various devices mounted on the hybrid vehicle 20, a timer 79 that executes time-measurement processing according to a time-measurement command, and an input / output port and a communication port (not shown) are provided. The hybrid electronic control unit 70 includes an ignition signal from an ignition switch 80, a shift position SP from a shift position sensor 82 that detects the operation position of the shift lever 81, and an accelerator pedal position sensor 84 that detects the amount of depression of the accelerator pedal 83. The accelerator opening Acc from the vehicle, the brake pedal position BP from the brake pedal position sensor 86 for detecting the depression amount of the brake pedal 85, the vehicle speed V from the vehicle speed sensor 88, and the like are input via the input port. The hybrid electronic control unit 70 outputs a drive signal to the system main relay 56 via an output port. As described above, the hybrid electronic control unit 70 is connected to the engine ECU 24, the motor ECU 40, and the battery ECU 52 via the communication port, and exchanges various control signals and data with the engine ECU 24, the motor ECU 40, and the battery ECU 52. ing.

  The hybrid vehicle 20 of the embodiment thus configured calculates the required torque to be output to the ring gear shaft 32a as the drive shaft based on the accelerator opening Acc and the vehicle speed V corresponding to the depression amount of the accelerator pedal 83 by the driver. Then, the operation of the engine 22, the motor MG1, and the motor MG2 is controlled so that the required power corresponding to the required torque is output to the ring gear shaft 32a. As operation control of the engine 22, the motor MG1, and the motor MG2, the operation of the engine 22 is controlled so that power corresponding to the required power is output from the engine 22, and all of the power output from the engine 22 is the power distribution and integration mechanism 30. Torque conversion operation mode in which the motor MG1 and the motor MG2 are driven and controlled so that the torque is converted by the motor MG1 and the motor MG2 and output to the ring gear shaft 32a, and the sum of the required power and the power required for charging and discharging the battery 50 The engine 22 is operated and controlled so that power corresponding to the power is output from the engine 22, and all or part of the power output from the engine 22 with charging / discharging of the battery 50 is performed by the power distribution and integration mechanism 30 and the motor MG1. The required power is converted to the ring gear shaft 32a by the torque conversion by the motor MG2. A charge / discharge operation mode in which the motor MG1 and the motor MG2 are controlled to be output, a motor operation mode in which the operation of the engine 22 is stopped and the power corresponding to the required power from the motor MG2 is output to the ring gear shaft 32a, etc. There is.

  Next, the operation of the thus configured hybrid vehicle 20 of the present embodiment, particularly, the operation when the voltage VH detected by the VH voltage sensor 93 is an overvoltage will be described. FIG. 3 is a flowchart showing an example of a drive control routine executed by the hybrid electronic control unit 70. This routine is repeatedly executed every predetermined time (for example, every several msec).

  When the drive control routine is executed, first, the CPU 72 of the hybrid electronic control unit 70 first determines the accelerator opening Acc from the accelerator pedal position sensor 84, the vehicle speed V from the vehicle speed sensor 88, the rotational speed Nm1, of the motors MG1, MG2. Nm2, the rotation speed Ne of the engine 22, the input / output limits Win and Wout of the battery 50, the voltage VH, and the timer flag F indicating that the timer 79 is measuring time are input. (Step S100). Here, the rotational speed Ne of the engine 22 is calculated based on a signal from a crank position sensor (not shown) attached to the crankshaft 26 and is input from the engine ECU 24 by communication. Further, the rotational speeds Nm1 and Nm2 of the motors MG1 and MG2 are input from the motor ECU 40 by communication from those calculated based on the rotational positions of the rotors of the motors MG1 and MG2 detected by the rotational position detection sensors 43 and 44. It is assumed that the voltage VH detected by the VH voltage sensor 93 is input from the motor ECU 40 by communication. Further, the input / output limits Win and Wout of the battery 50 are set based on the battery temperature Tb of the battery 50 detected by the temperature sensor 51 and the remaining capacity (SOC) of the battery 50 from the battery ECU 52 by communication. To do. The timer flag F is set to a value of 1 when the timer 79 is measuring time, as described later, and is set to a value of 0 when the timer 79 is reset. When this routine is executed for the first time, the timer flag F is set. The value is set to 0.

  When the data is thus input, the CPU 72 determines whether or not the input timer flag F is 0 (step S110), and determines whether or not the voltage VH is equal to or higher than the overvoltage threshold (step S120). Here, the overvoltage threshold is defined as a voltage value that may adversely affect the in-vehicle device. Considering the case where the voltage VH does not exceed the overvoltage threshold, the timer flag F is set to a value of 0, so that an affirmative determination is made in step S110 and a negative determination is made in the subsequent step S120. Next, a gate permission command for permitting gates of all of the transistors T11 to T16 and T21 to 26 of the inverters 41 and 42 and the transistors T31 and T32 of the step-up / down converter 55 is transmitted to the motor ECU 40 (step S130). Thereby, switching control of the inverters 41 and 42 and the step-up / step-down converter 55 by the motor ECU 40 becomes possible. Note that if the voltage VH does not exceed the overvoltage threshold at the beginning of this drive control routine, the transistors will not be gated off, but just in case the gate permission of all transistors is transmitted. did.

  Thus, after transmitting the gate permission of all the transistors to the motor ECU 40, the ring gear as the drive shaft connected to the drive wheels 63a and 63b as the torque required for the vehicle based on the input accelerator opening Acc and the vehicle speed V. A required torque Tr * to be output to the shaft 32a and a required power Pe * required for the engine 22 are set (step S140). In the embodiment, the required torque Tr * is determined in advance by storing the relationship between the accelerator opening Acc, the vehicle speed V, and the required torque Tr * in the ROM 74 as a required torque setting map, and the accelerator opening Acc, the vehicle speed V, , The corresponding required torque Tr * is derived and set from the stored map. FIG. 4 shows an example of the required torque setting map. The required power Pe * can be calculated as the sum of the set required torque Tr * multiplied by the rotational speed Nr of the ring gear shaft 32a and the charge / discharge required power Pb * required by the battery 50 and the loss Loss. The rotation speed Nr of the ring gear shaft 32a can be obtained by multiplying the vehicle speed V by the conversion factor k, or can be obtained by dividing the rotation speed Nm2 of the motor MG2 by the gear ratio Gr of the reduction gear 35.

  Subsequently, the target rotational speed Ne * and the target torque Te * of the engine 22 are set based on the set required power Pe * (step S150). This setting is performed based on an operation line for efficiently operating the engine 22 and the required power Pe *. FIG. 5 shows an example of the operation line of the engine 22 and how the target rotational speed Ne * and the target torque Te * are set. As shown in the figure, the target rotational speed Ne * and the target torque Te * can be obtained from the intersection of the operation line and a curve with a constant required power Pe * (Ne * × Te *).

  Next, using the set target rotational speed Ne *, the rotational speed Nr (Nm2 / Gr) of the ring gear shaft 32a, and the gear ratio ρ of the power distribution and integration mechanism 30, the target rotational speed Nm1 of the motor MG1 is given by the following equation (1). * Is calculated and a torque command Tm1 * of the motor MG1 is calculated by equation (2) based on the calculated target rotational speed Nm1 * and the current rotational speed Nm1 (step S160). Here, Expression (1) is a dynamic relational expression for the rotating element of the power distribution and integration mechanism 30. FIG. 6 is a collinear diagram showing the dynamic relationship between the rotational speed and torque in the rotating elements of the power distribution and integration mechanism 30. In FIG. In the figure, the left S-axis indicates the rotation speed of the sun gear 31 that is the rotation speed Nm1 of the motor MG1, the C-axis indicates the rotation speed of the carrier 34 that is the rotation speed Ne of the engine 22, and the R-axis indicates the rotation speed of the motor MG2. The rotational speed Nr of the ring gear 32 obtained by dividing the number Nm2 by the gear ratio Gr of the reduction gear 35 is shown. Expression (1) can be easily derived by using this alignment chart. The two thick arrows on the R axis indicate that the torque Tm1 output from the motor MG1 acts on the ring gear shaft 32a and the torque Tm2 output from the motor MG2 acts on the ring gear shaft 32a via the reduction gear 35. Torque. Expression (2) is a relational expression in feedback control for rotating the motor MG1 at the target rotational speed Nm1 *. In Expression (2), “k1” in the second term on the right side is a gain of a proportional term. “K2” in the third term on the right side is the gain of the integral term.

Nm1 * = Ne * ・ (1 + ρ) / ρ-Nm2 / (Gr ・ ρ) (1)
Tm1 * = previous Tm1 * + k1 (Nm1 * -Nm1) + k2∫ (Nm1 * -Nm1) dt (2)

  When the target rotational speed Nm1 * and the torque command Tm1 * of the motor MG1 are thus calculated, the input / output limits Win and Wout of the battery 50 and the calculated torque command Tm1 * of the motor MG1 are multiplied by the current rotational speed Nm1 of the motor MG1. Torque limits Tmin and Tmax as upper and lower limits of the torque that may be output from the motor MG2 by dividing the deviation from the obtained power consumption (generated power) of the motor MG1 by the rotational speed Nm2 of the motor MG2 is expressed by the following equation (3). Further, the temporary motor torque Tm2tmp as the torque to be output from the motor MG2 is calculated using the required torque Tr *, the torque command Tm1 *, and the gear ratio ρ of the power distribution and integration mechanism 30 (step S170). Calculated by equation (5) (step S180), and with the calculated torque limits Tmin and Tmax Setting the torque command Tm2 * of the motor MG2 as a value obtained by limiting the motor torque Tm2tmp (step S190). By setting the torque command Tm2 * of the motor MG2 in this way, the required torque Tr * output to the ring gear shaft 32a as the drive shaft is set as a torque limited within the range of the input / output limits Win and Wout of the battery 50. can do. Equation (5) can be easily derived from the collinear diagram of FIG. 6 described above.

Tmin = (Win-Tm1 * ・ Nm1) / Nm2 (3)
Tmax = (Wout-Tm1 * ・ Nm1) / Nm2 (4)
Tm2tmp = (Tr * + Tm1 * / ρ) / Gr (5)

  When the target rotational speed Ne * and target torque Te * of the engine 22 and the torque commands Tm1 * and Tm2 * of the motors MG1 and MG2 are set in this manner, the target rotational speed Ne * and the target torque Te * are transmitted to the engine ECU 24 with the torque command Tm1. * And Tm2 * are transmitted to the motor ECU 40 (step S200), and this routine is terminated. The engine ECU 24 that has received the target rotational speed Ne * and the target torque Te * performs fuel injection control, ignition control, and intake air amount control so that the engine 22 is operated at an operating point based on the target rotational speed Ne * and the target torque Te *. And so on. Also, the motor ECU 40 that has received the torque commands Tm1 * and Tm2 * controls the inverters 41 and 42 and the step-up / down converter 55 so that the motor MG1 is driven by the torque command Tm1 * and the motor MG2 is driven by the torque command Tm2 *. Perform switching control. As a result, power corresponding to the torque commands Tm1 * and Tm2 * is output from the motors MG1 and MG2, and power corresponding to the required torque Tr * is output from the engine 22 and the motors MG1 and MG2.

  Next, considering that the voltage VH detected by the VH voltage sensor has exceeded the overvoltage threshold for the first time, an affirmative determination is made in step S110, and an affirmative determination is made in subsequent step S120. Here, for example, when the motor MG1 is in a regenerative operation, the voltage VH can be supplied to the battery 50 by stepping down the high voltage power by switching control of the step-up / down converter 55 when the upper arm is in an off failure. In other words, regenerative power without a destination continues to be stored in the capacitor 57 and exceeds the overvoltage threshold. Then, the CPU 72 starts time measurement by the timer 79, sets a value 1 indicating that the timer 79 is measuring time in the timer flag F, and increments an overvoltage history counter value (hereinafter, counter value) by one. (Step S210). Here, the counter value falls below a gate permission voltage threshold described later when the voltage VH first exceeds the overvoltage threshold or after the voltage VH exceeds the overvoltage threshold, and again exceeds the overvoltage threshold. The counter is incremented by one when the initial value is set to a value of 0, and is reset to a value of 0 by turning off the ignition switch 80.

  Subsequently, the CPU 72 sets a value 0 to the torque commands Tm1 * and Tm2 * of the motors MG1 and MG2, and this torque command and the transistors T11 to T16 and T21 to 26 of the inverters 41 and 42 and the transistors of the buck-boost converter 55 are set. A gate shut-off command for gate shutting off all of T31 and T32 is transmitted to the motor ECU 40 and a self-sustained operation command for the engine 22 is transmitted to the engine ECU 24 (step S220). The engine ECU 24 that has received the self-sustained operation command sucks in the engine 22 so that the engine 22 operates autonomously, that is, when the engine 22 is stopped, the engine ECU 24 is stopped, and when the engine 22 is operating, gradually becomes an idle speed. Controls such as air volume control, fuel injection control, and ignition control are performed. The motor ECU 40 that has received the gate cutoff command and the torque commands Tm1 * and Tm2 * causes the transistors T11 to T16 and T21 to 26 of the inverters 41 and 42 and the transistor T31 of the buck-boost converter 55 to prevent torque from being output by the motors MG1 and MG2. All of T32 is gated off. In this way, the electric power stored in the capacitor 57 is discharged by a resistor (not shown) connected in parallel to the capacitor 57 without adversely affecting the in-vehicle device, and the voltage VH decreases as the capacitor 57 is discharged. Recovers below the gate permission threshold.

  Next, it is determined whether or not the measured value T of the timer 79 is less than a predetermined time (step S230). Here, the predetermined time is set to 5 sec, for example. Immediately after the gate is shut off in step S220, the measured value T of the timer 79 is less than the predetermined time, so an affirmative determination is made in step S230, and it is determined whether or not the voltage VH is less than the gate permission threshold (step S240). Here, the gate permission threshold is defined as a voltage at which the in-vehicle device can be safely driven. Immediately after the gate is shut off, since the voltage VH is equal to or higher than the gate permission voltage, a negative determination is made in step S240, and this routine is terminated.

  When this routine is executed again, since the timer 79 is measuring time, the timer flag F is set to a value of 1, and a negative determination is made in step S110. If the measured value T of the timer 79 is less than the predetermined time (5 sec), an affirmative determination is made in step S230, and it is determined whether or not the voltage VH is less than the gate permission threshold (step S240). In this way, this routine is repeated, and if the voltage VH falls below the gate permission threshold value while the measured value T of the timer 79 is less than the predetermined time, an affirmative determination is made in step S240 and the timer 79 is reset to 0. At the same time, a value 0 is set in the timer flag F (step S250), and it is determined whether or not the counter value is equal to or greater than a predetermined value (here, value 2) (step S260). Now, considering that the voltage VH has exceeded the overvoltage threshold for the first time, the counter value is 1. Therefore, a negative determination is made in step S260, and the transistors T11 to T16, T21 to 26 of the inverters 41 and 42, and A gate permission command for permitting gates of all the transistors T31 and T32 of the step-up / down converter 55 is transmitted to the motor ECU 40 (step S130). Thereafter, the processes of steps S140 to S200 described above are executed, and this routine is terminated. That is, normal traveling is possible.

  Next, consider a case where the voltage VH again exceeds the overvoltage threshold while the counter value is set to the value 1. In this case, since the timer flag F is 0, an affirmative determination is made in step S110, and an affirmative determination is made in subsequent step S120. Next, since the counter value is incremented by 1 (step S210), the counter value is set to the value 2. Thereafter, while the same processing as described above is repeated, an affirmative determination is made in step S260 that the counter value is greater than or equal to a predetermined value. In this case, since the counter value is equal to or greater than a predetermined value (value 2) within a predetermined period (here, so-called one trip, that is, a period from when the ignition switch 80 is turned on to when it is turned off), the buck-boost converter It is considered that the step-down operation is hindered due to the off-fault of the upper arm 55, and if it is left as it is, there is a possibility that the on-vehicle equipment may be undesirably affected by the overvoltage, and the shift is made to the retreat travel. Then, a gate permission command for allowing only the transistors T21 to T26 of the inverter 42 to be gated is transmitted to the motor ECU 40 (step S270). Subsequently, a value of 0 is set for the target rotational speed Ne * and the required power Pe * of the engine 22 and a value of 0 is set for the torque command Tm1 * of the motor MG1 (step S280) so that the motor MG2 does not perform a regenerative operation. A value of 0 is set in the torque limit Tmin as the lower limit of the torque that may be output from the motor MG2, and the torque limit Tmax as the upper limit of the torque is calculated (step S290). Then, a temporary motor torque Tm2tmp as a torque to be output from the motor MG2 is calculated using the required torque Tr *, the torque command Tm1 * (value 0), and the gear ratio ρ of the power distribution and integration mechanism 30 (step S180). Tr * at this time may be obtained according to FIG. 4 based on the accelerator opening Acc and the vehicle speed V, or from a torque setting map for retreat travel in which a torque smaller than the required torque shown in FIG. 4 is set. You may ask for it. Next, the torque command Tm2 * of the motor MG2 is set as a value obtained by limiting the temporary motor torque Tm2tmp with the calculated torque limits Tmin (value 0) and Tmax (step S190). When the target rotational speed Ne * and target torque Te * of the engine 22 and the torque commands Tm1 * and Tm2 * of the motors MG1 and MG2 are set in this manner, the target rotational speed Ne * and the target torque Te * are transmitted to the engine ECU 24 with the torque command Tm1. * And Tm2 * are transmitted to the motor ECU 40 (step S200), and this routine is terminated. As a result, the voltage cannot be stepped up / down by switching control of the step-up / down converter 55, but the remaining capacity (SOC) of the battery 50 is supplied to the inverter 42 via the diode D31 and retreats with the power of the motor MG2. It becomes possible to do. At this time, the remaining capacity of the capacitor 57 is also supplied to the inverter 42.

  On the other hand, if the time value T of the timer 79 is equal to or longer than the predetermined time (5 sec) before the voltage VH falls below the gate permission threshold, a negative determination is made in step S230. In this case, since the voltage VH does not fall below the gate permission threshold value within a predetermined time, it is considered that a failure other than the upper arm OFF failure has occurred in the buck-boost converter 55. Shift to ready-off as there is a great risk of impact. That is, ready-off is executed in which the engine 22 and the motors MG1, MG2 are stopped to turn off the system (step S300), and this routine is terminated. Thereby, the inconvenience (for example, damage of vehicle equipment) by the subsequent drive of the engine 22 and motor MG1, MG2 can be suppressed.

  Next, the operations of the inverters 41 and 42, the step-up / down converter 55, and the like when the drive time control routine of FIG. 3 is executed will be described with reference to FIG. As shown in FIG. 7, if the voltage VH exceeds the overvoltage threshold at time t0, the transistors T11 to T16 and T21 to 26 of the inverters 41 and 42 and the transistors T31 and T32 of the buck-boost converter 55 are at that time. All are gated (step S220). As a result, the electric power stored in the capacitor 57 is discharged by a resistor (not shown) connected in parallel to the capacitor 57. At time t1, when the voltage VH decreases with the discharge of the capacitor 57 and falls below the gate permission threshold, the transistors T11 to T16 and T21 to 26 of the inverters 41 and 42 and the transistors T31 and T32 of the buck-boost converter 55 are displayed. Are permitted to be gated (step S130). Next, when the voltage VH again exceeds the overvoltage threshold at time t2, all of the transistors T11 to T16, T21 to 26 of the inverters 41 and 42 and the transistors T31 and T32 of the buck-boost converter 55 are gated again. (Step S220). Thereby, the electric power stored in the capacitor 57 is discharged again by a resistor (not shown). At time t3, when voltage VH decreases with the discharge of capacitor 57 and falls below the gate permission threshold, only transistors T21 to T26 of inverter 42 are gate permitted (step S270).

  According to the hybrid vehicle 20 described above, when the number of times that the voltage VH exceeds the overvoltage threshold value within one trip is two times or more, it is considered that the step-down operation of the step-up / down converter 55 is hindered, and the motor The step-up / down converter 55 and the inverters 41 and 42 are controlled so that the motor MG2 is operated by the electric power of the battery 50 in a state where the charging of the battery 50 by the MG1 and MG2 is prohibited. As a result, the overvoltage is eliminated, and the motor MG2 is driven by the power of the battery 50 to be able to run on its own. Therefore, evacuation traveling can be secured while protecting the in-vehicle device from overvoltage.

  In the hybrid vehicle 20 of the embodiment, the vehicle travels when the voltage VH exceeds the overvoltage threshold for the second time, but when the voltage VH exceeds the first time or exceeds three times more than three times. It is good also as what carries out retreating. In that case, it is only necessary to set one or a plurality of three or more values as the predetermined value when determining whether or not the overvoltage history counter value is equal to or larger than the predetermined value.

  In the hybrid vehicle 20 of the embodiment, one trip is set as the predetermined period, but may be a predetermined traveling time, a traveling distance, a number of days, or the like.

  In the hybrid vehicle 20 of the embodiment, the overvoltage on the motor MG1, MG2 side of the buck-boost converter 55 is determined based on whether or not the voltage VH detected by the VH voltage sensor 93 exceeds the overvoltage threshold. Instead of using the voltage VH detected in step S120 of FIG. 3, the following may be used. That is, when either of the motors MG1 and MG2 is performing regenerative operation and the charging current of the battery 50 is 0, it may be predicted that an overvoltage will occur. Here, the regenerative operation of the motors MG1, MG2 is determined from the rotational speeds Nm1, Nm2 and torques Tm1, Tm2 of the motors MG1, MG2, and the charging current of the battery 50 is the charge / discharge current from the current sensor of the battery 50. It may be determined by inputting. At this time, it may be added that the voltage VH exceeds the gate permission voltage. If the balance of electric power is to be balanced by the motors MG1 and MG2, the battery 50 is not charged / discharged.

  In the hybrid vehicle 20 of the embodiment, the power of the motor MG2 is shifted by the reduction gear 35 and output to the ring gear shaft 32a. However, as illustrated in the hybrid vehicle 120 of the modified example of FIG. May be connected to an axle (an axle connected to the wheels 64a and 64b in FIG. 8) different from an axle to which the ring gear shaft 32a is connected (an axle to which the drive wheels 63a and 63b are connected).

  In the hybrid vehicle 20 of the embodiment, the power of the engine 22 is output to the ring gear shaft 32a as the drive shaft connected to the drive wheels 63a and 63b via the power distribution and integration mechanism 30, but the modified example of FIG. The hybrid vehicle 220 includes an inner rotor 232 connected to the crankshaft 26 of the engine 22 and an outer rotor 234 connected to a drive shaft that outputs power to the drive wheels 63a and 63b. A counter-rotor motor 230 that transmits a part of the power to the drive shaft and converts the remaining power into electric power may be provided.

  In the hybrid vehicle 20 of the embodiment, a series / parallel hybrid type is adopted. However, a series hybrid type in which a motor drives a wheel by electric power generated by driving a generator with an engine may be adopted. You may employ | adopt the parallel hybrid type which drives a wheel directly by both.

  In the embodiment, the present invention is applied to the hybrid vehicle 20. However, the present invention may be applied to a vehicle equipped with a power supply device that exchanges electric power with an electric device, for example, an electric vehicle.

  Here, 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 motor MG1 corresponds to the “generator”, the motor MG2 corresponds to the “electric motor”, the battery 50 corresponds to the “electric storage unit”, the engine 22 corresponds to the “internal combustion engine”, and the voltage VH is The step-up / down converter 55, the inverters 41 and 42, and the engine 22 are controlled so that the voltage VH recovers below the gate permission voltage threshold when the overvoltage threshold is exceeded, while the voltage VH exceeds the overvoltage threshold within one trip. When the number of times exceeding the value is less than 2, the voltage VH recovers below the gate permission voltage threshold value, and then power is exchanged between the motors MG1 and MG2 and the battery 50 so that the step-up / down converter 55 and the inverter 41, 42 and the engine 22 are controlled, and the number of times that the voltage VH output to the motors MG1 and MG2 exceeds the overvoltage threshold in one trip is two times or more. The step-up / down converter 55, the inverters 41 and 42, and the engine 22 are connected so that the motor MG2 is driven by the power of the battery 50 with the discharge of the battery 50 while the charging of the battery 50 by the motor MG1 and the motor MG2 is prohibited. The hybrid electronic control unit 70, the engine ECU 24, and the motor ECU 40 to be controlled correspond to “control means”. Here, the “motor” is not limited to the motors MG1 and MG2 configured as the synchronous generator motors, and may be any type of motor as long as it can input and output power to the axle such as an induction motor. It doesn't matter. The “storage means” is not limited to the battery 50 as a secondary battery (for example, a lithium ion battery, a nickel metal hydride battery, a nickel cadmium battery, or a lead storage battery), but an electric double layer capacitor, a hybrid capacitor, or a pseudo-capacitance capacitor As long as the electric power can be exchanged with the electric motor, it may be anything. As the “buck-boost converter”, two gate type switching elements (for example, insulated gate bipolar transistors) Tr1 and Tr2, and two switching elements Tr1 and Tr2 attached to hold a voltage in parallel are provided. The present invention is not limited to the one provided with the diodes D1 and D2, the intermediate between the two switching elements Tr1 and Tr2, and the reactor L attached to the positive electrode side of the battery 50. Any device can be used as long as it can be supplied and can be supplied to the driving device without increasing the voltage of the DC power supply. The “internal combustion engine” may be any type of internal combustion engine that outputs motive power using volatile fuel. The “control means” is not limited to the combination of the hybrid electronic control unit 70, the engine ECU 24, and the motor ECU 40, and may be configured by a single electronic control unit, or may be a battery ECU 52 or the like. The electronic control unit may be added. 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. It is an example for specifically explaining the best mode for doing so, and does not limit the elements of the invention described in the column of means for solving the problem. In other words, the interpretation of the invention described in the column of means for solving the problem 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 problem. It is only a specific example.

  The best mode for carrying out the present invention has been described with reference to the embodiments. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the gist of the present invention. Of course, it can be implemented in the form.

  The present invention can be used in the automobile manufacturing industry and the like.

1 is a configuration diagram showing an outline of the configuration of a hybrid vehicle 20. FIG. It is a block diagram which shows the outline of a structure of the electric drive system containing motor MG1, MG2. It is a flowchart which shows an example of a drive control routine. It is explanatory drawing which shows an example of the map for request | requirement torque setting. It is explanatory drawing which shows a mode that an example of the operating line of the engine 22, and target rotational speed Ne * and target torque Te * are set. FIG. 4 is an explanatory diagram showing an example of a collinear diagram for dynamically explaining rotational elements of a power distribution and integration mechanism 30. 4 is a time chart for explaining operations of inverters 41 and 42 and a step-up / down converter 55 when a drive control routine is executed. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 120 according to a modification. FIG. 11 is a configuration diagram showing an outline of a configuration of a hybrid vehicle 220 of a modified example.

Explanation of symbols

  20, 120, 220 Hybrid vehicle, 22 engine, 24 engine electronic control unit (engine ECU), 26 crankshaft, 28 damper, 30 power distribution integration mechanism, 31 sun gear, 32 ring gear, 32a ring gear shaft, 33 pinion gear, 34 carrier 35, reduction gear, 40 motor electronic control unit (motor ECU), 41, 42 inverter, 43, 44 rotational position detection sensor, 50 battery, 51 temperature sensor, 52 battery electronic control unit (battery ECU), 54 power line , 54a Positive bus, 54b Negative bus, 55 Buck-boost converter, 56 System main relay, 57, 59 Capacitor, 60 Gear mechanism, 62 Differential gear, 63a, 63b Drive wheel, 64a, 64b Wheel, 70 Hybrid electronic control unit, 72 CPU, 74 ROM, 76 RAM, 78 Flash memory, 79 Timer, 80 Ignition switch, 81 Shift lever, 82 Shift position sensor, 83 Accel pedal, 84 Accel pedal position sensor, 85 Brake Pedal, 86 Brake pedal position sensor, 88 Vehicle speed sensor, 92 VL voltage sensor, 93 VH voltage sensor, 230 Pair rotor motor, 232 Inner rotor, 234 Outer rotor, MG1, MG2 motor, T11-T16, T21-26, T31, T32 transistor, D11 to D16, D21 to D26, D31, D32 diode, L reactor.

Claims (6)

A high-voltage motor that can input and output power to the axle;
Low-voltage power storage means capable of exchanging electric power with the electric motor with charging and discharging;
A high voltage that is provided between the electric motor and the electric storage means, inputs low-voltage electric power on the electric storage means side, boosts the electric power to high-voltage electric power, outputs the electric power to the electric motor side, or is generated by regenerative operation of the electric motor A step-up / step-down converter that inputs the electric power of the current and lowers the electric power to a low-voltage electric power and outputs it to the power storage means side;
When the voltage on the motor side of the buck-boost converter exceeds a predetermined threshold value, the buck-boost converter and the motor are controlled so that the voltage recovers below the threshold value. When the number of times that the voltage on the motor side exceeds the threshold value within a predetermined period is less than a predetermined reference number, power is transferred between the motor and the power storage means after the voltage recovers below the threshold value. The step-up / down converter and the electric motor are controlled so as to be exchanged, and when the number of times that the voltage on the motor side of the step-up / down converter exceeds the threshold value within a predetermined period is greater than or equal to a predetermined reference number, the electric motor The step-up / step-down converter and the electric motor so that the electric motor is operated by the electric power of the electric storage means with the discharging of the electric storage means in a state where charging of the electric storage means is prohibited And control means for controlling,
A vehicle comprising: The step-up / step-down converter is connected between a positive electrode terminal of the power storage means and the electric motor, and turns on and off a current flow from the electric motor to the positive electrode terminal, the first switching element and the positive electrode terminal A second switching element connected between the intermediate point between the intermediate point and the negative electrode terminal of the power storage means and turning on and off the current flow from the intermediate point to the negative electrode terminal; and connected between the intermediate point and the positive electrode terminal And a first diode connected in parallel with the first switching element and allowing only a current flow from the intermediate point to the electric motor, and connected in parallel with the second switching element and from the negative terminal A second diode that only allows current flow to the midpoint, and by adjusting the on-time of both switching elements at a predetermined period, Input the low voltage power on the power storage means side to boost the high voltage power and output it to the motor side, or input the high voltage power generated by the regenerative operation of the motor to step down to the low voltage power and Output to the storage means side,
When the number of times that the high voltage output to the electric motor side exceeds the threshold value within a predetermined period is equal to or greater than a predetermined reference number, the control means controls the current flow of the switching elements of the buck-boost converter. Turn off,
The vehicle according to claim 1. The vehicle according to claim 1 or 2,
A smoothing capacitor that is connected in parallel to the electric motor as viewed from the step-up / down converter and smoothes the high voltage on the electric motor side of the step-up / down converter;
The control means inputs the inter-terminal voltage of the smoothing capacitor as a high voltage output to the motor side,
vehicle. The electric motor receives power supply via an inverter circuit that converts DC power output from the buck-boost converter into AC power.
The vehicle according to any one of claims 1 to 3. The vehicle according to any one of claims 1 to 4,
An internal combustion engine capable of inputting and outputting power to the axle;
A high-voltage generator connected in parallel with the electric motor as viewed from the power storage means, capable of exchanging electric power with the power storage means, and capable of generating power using power from the internal combustion engine;
With
The control means includes the step-up / down converter, the electric motor, the generator, and the generator so that when the voltage on the electric motor side of the step-up / down converter exceeds a predetermined threshold, the voltage recovers below the threshold. While controlling the internal combustion engine, when the number of times that the voltage on the electric motor side of the step-up / down converter exceeds the threshold value within a predetermined period is less than a predetermined reference number, the voltage has recovered below the threshold value Further, the buck-boost converter, the motor, the generator, and the internal combustion engine are controlled so that electric power is exchanged between the motor and the power storage means, and the voltage on the motor side of the buck-boost converter is set for a predetermined period. When the number of times the threshold value is exceeded is equal to or greater than a predetermined reference number, charging of the power storage means with the generator and the electric motor is prohibited, accompanied by discharge of the power storage means. The controls the internal combustion engine and the generator and the step-up and step-down converter and the electric motor so that said by the power of the power storage unit motor is operated,
vehicle. A high-voltage electric motor capable of inputting / outputting power to and from the axle, a low-voltage electric storage means capable of exchanging electric power with the electric motor with charge / discharge, and provided between the electric motor and the electric storage means, Input the low voltage power on the power storage means side to boost the high voltage power and output it to the motor side, or input the high voltage power generated by the regenerative operation of the motor to step down to the low voltage power and A control method for a vehicle comprising a step-up / step-down converter that outputs to the power storage means side,
When the voltage on the motor side of the buck-boost converter exceeds a predetermined threshold value, the buck-boost converter and the motor are controlled so that the voltage recovers below the threshold value. When the number of times that the voltage on the motor side exceeds the threshold value within a predetermined period is less than a predetermined reference number, power is transferred between the motor and the power storage means after the voltage recovers below the threshold value. The step-up / down converter and the electric motor are controlled so as to be exchanged. The step-up / step-down converter and the electric motor so that the electric motor is operated by the electric power of the electric storage means with the discharging of the electric storage means in a state where charging of the electric storage means is prohibited To control,
Vehicle control method.

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