JP2016010280A - Control device for electric vehicles - Google Patents

Abstract

To provide a control device for an electric vehicle capable of shortening a time required for pre-charging to be completed at an early stage and enabling vehicle travel.
A high voltage battery 2 capable of storing a high voltage, a DCDC converter 4 for stepping down an output voltage of the high voltage battery 2, a low voltage battery 3 connected to an output terminal of the DCDC converter 4, and an ignition switch. When turned on, the controller 7 that starts the precharge that turns on the precharge contactor 12 and the minus contactor 14 to charge the capacitor 41, and the output voltage of the DCDC converter 4 to the same voltage as the low voltage battery 3 during the precharge. A voltage adjusting unit 71 to be set.
[Selection] Figure 1

Description

  According to the present invention, in a vehicle equipped with a high-voltage device such as a traveling motor driven by electric power, excessive power to the high-voltage device suddenly flows when the high-voltage device is driven, such as when the vehicle is started. The present invention relates to a control device for an electric vehicle having a function of preventing the vehicle from moving.

  In a vehicle equipped with a traveling motor as a traveling drive source, a high voltage battery that stores DC power of a relatively high voltage, for example, about 200 V, an inverter that converts DC power of the high voltage battery into AC power, and conversion by the inverter The vehicle is caused to travel by rotationally driving a driving wheel that is connected to the output shaft of the traveling motor so as to transmit power.

  Such a vehicle includes a low-voltage battery that stores DC power of a relatively low voltage, for example, 12 V, separately from the high-voltage battery, and various kinds of vehicles for controlling the lighting of the vehicle and the vehicle by the power of the low-voltage battery. Low voltage system devices such as controllers are operated.

  The low voltage battery is connected to the high voltage battery via a direct current (DC) DC converter so that the high voltage output voltage of the high voltage battery is converted into a low voltage by the DCDC converter and stored in the low voltage battery. It has become.

  Further, a main contactor for connecting / disconnecting electrical connection with the high voltage battery is interposed between the high voltage battery and the inverter. In addition, a capacitor for smoothing the input voltage is provided at the input end of the inverter in order to suppress voltage fluctuation supplied from the high voltage battery.

  However, if the main contactor is turned on and a direct current from a high voltage battery is input to the inverter, a very large current flows into the capacitor in a short time, which may result in damage such as welding of the contact of the main contactor. .

  Therefore, a precharge contactor and a precharge resistor are provided in parallel with the main contactor, the precharge contactor is turned on before turning on the main contactor, the capacitor is gradually charged, and the potential difference between the high voltage battery and the capacitor is reduced. Turn the main contactor on when it gets smaller. By performing such precharge control, the main contactor is not damaged.

  In such a vehicle, when the DCDC converter operates during precharging, the current necessary for precharging the capacitor is consumed by the DCDC converter, and the precharging is not completed.

  In order to solve this problem, there is a vehicle in which an operation permission signal for turning on or off the operation of the DCDC converter is input to the DCDC converter so that the DCDC converter is not operated during precharging. In such a vehicle, even when a communication line that transmits an operation permission signal is disconnected, the DCDC converter is controlled so that the operation can be continued.

Therefore, if the communication line is disconnected, the DCDC converter operates during precharging, and precharging is not completed.
In Patent Document 1, it is detected whether or not the communication line is disconnected. When the disconnection is detected, the abnormal lamp is lit without shutting off the power supply from the high voltage battery and performing precharging. It is like that.

  In such a vehicle, when the communication line that transmits the operation permission signal is disconnected, the pre-charge cannot be performed, and thus the operation of the DCDC converter cannot be started. In addition, since power is not supplied from the high voltage battery, power is not supplied to the inverter, and the traveling motor cannot be driven.

Japanese Patent No. 3963155

Thus, when the DCDC converter operates during precharge, current is consumed by the DCDC converter and precharge is not completed. Even if the operation of the DCDC converter is stopped by the operation permission signal, if the communication line that transmits the operation permission signal is disconnected, the DCDC converter operates and precharging is not completed. In Patent Document 1, the disconnection of the communication line is detected, but even if it is detected, the precharge cannot be completed and the vehicle cannot travel.
Therefore, an object of the present invention is to provide a control device for an electric vehicle that can complete precharge early and reduce the time until the vehicle can travel.

  An aspect of the invention of a control device for an electric vehicle that solves the above problems includes a high-voltage battery that can store high-voltage power, a voltage converter that steps down the output voltage of the high-voltage battery, and an output terminal of the voltage converter A control device for an electric vehicle comprising: a low-voltage battery connected to a capacitor; a capacitor connected between input terminals of the voltage converter; and a precharge circuit for precharging the capacitor. The voltage adjustment unit adjusts the output voltage of the battery, and the voltage adjustment unit sets the output voltage of the voltage converter to the same voltage as that of the low voltage battery during the precharge of the capacitor.

  As described above, according to one aspect of the present invention, the output voltage of the voltage converter is set to the same voltage as that of the low voltage battery during the precharge, so that no current flows from the voltage converter. Therefore, the current required for precharging is not consumed by the voltage converter, and it is possible to shorten the time until the vehicle can run by completing precharging early.

FIG. 1 is a diagram showing a control device for an electric vehicle according to an embodiment of the present invention, and is a conceptual block diagram thereof. FIG. 2 is a diagram illustrating a control device for an electric vehicle according to an embodiment of the present invention, and is a flowchart illustrating the precharge control process. FIG. 3 is a diagram showing a control device for an electric vehicle according to an embodiment of the present invention, and is a time chart for explaining the precharge control process.

Hereinafter, an electric vehicle control apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings.
In FIG. 1, a vehicle 1 equipped with the control device for an electric vehicle according to the present embodiment includes a high voltage battery 2, a low voltage battery 3, a DCDC converter 4, a high voltage system device 5, and a low voltage system device 6. And the controller 7.

  The high voltage battery 2 is made of, for example, a nickel storage battery, a lithium storage battery, or the like, and has an output voltage of about 200 V, and is configured by connecting a plurality of cells in series. The high voltage battery 2 includes a voltage sensor 21 that detects a cell voltage of each cell, a temperature sensor 22 that detects the temperature of the high voltage battery 2, a current sensor 23 that detects a charging current and a discharging current, and the like. A DCDC converter 4 and a high voltage system device 5 are connected in parallel to the output terminal of the high voltage battery 2. That is, the high voltage battery 2 supplies power to the DCDC converter 4 and the high voltage system device 5. The high-voltage system device 5 includes a motor inverter that controls driving of a traveling motor that is a traveling drive source of the vehicle 1, an electric compressor for air conditioning, and the like.

  A plus contactor 11 is connected to the plus terminal of the high voltage battery 2, and a series connection circuit of a precharge contactor 12 and a precharge resistor 13 is connected in parallel with the plus contactor 11. A negative contactor 14 is connected to the negative terminal of the high voltage battery 2. The plus contactor 11, the precharge contactor 12, and the minus contactor 14 are switches that turn on or off the connection between the high voltage battery 2, the DCDC converter 4, and the high voltage system device 5. On / off of the plus contactor 11, the precharge contactor 12, and the minus contactor 14 is controlled by the controller 7.

The low voltage battery 3 is made of, for example, a lead storage battery, has an output voltage of about 12 V, and supplies electric power for driving various low voltage system devices 6 such as an electrical system of the vehicle 1.
The DCDC converter 4 converts the high voltage output voltage of the high voltage battery 2 into a low voltage and supplies it to the low voltage battery 3. The DCDC converter 4 includes a capacitor 41, a transistor 42, a high voltage side coil 43, a low voltage side coil 44, an iron core 45, a control unit 46, and a capacitor voltage sensor 47.

  The capacitor 41 is connected between the input terminals from the high voltage battery 2, and suppresses and smoothes the voltage fluctuation of the power supplied from the high voltage battery 2. The capacitor 41 is provided with a capacitor voltage sensor 47 that detects a voltage between terminals of the capacitor 41.

  The high voltage side coil 43 is connected in parallel with the capacitor 41. The low voltage side coil 44 is provided to face the high voltage side coil 43 with the iron core 45 interposed therebetween. When a current flows through the high voltage side coil 43, a magnetic field is generated, and this magnetic field generates a magnetic field also at the low voltage side coil 44 side, and a current flows. The voltage on the low voltage side coil 44 side is determined by the ratio of the number of turns of the high voltage side coil 43 and the number of turns of the low voltage side coil 44. Thus, the DCDC converter 4 constitutes a voltage converter in the present invention.

  The transistor 42 is connected in series with the high voltage side coil 43 and turns on or off the current flowing through the high voltage side coil 43. The control unit 46 can control the voltage on the low voltage side coil 44 side by controlling the on period and the off period of the transistor 42. The controller 46 is connected to a communication line to which an operation permission signal is transmitted from the controller 7 and a communication line to which a voltage command signal is transmitted.

  The control unit 46 turns off the transistor 42 while the operation permission signal is off, so that no current flows through the high-voltage side coil 43 and the DCDC converter 4 does not operate. While the operation permission signal is on, the control unit 46 controls on / off of the transistor 42 according to the voltage value of the voltage command signal, and the voltage value of the low voltage side coil 44 becomes the voltage value of the voltage command signal. Control to be. A low voltage battery 3 and a low voltage system device 6 are connected in parallel to the output of the DCDC converter 4.

  The controller 7 includes a computer unit that includes a central processing unit (CPU), a random access memory (RAM), a read only memory (ROM), a flash memory, an input port, and an output port.

  The ROM of the controller 7 stores a program for causing the computer unit to function as the controller 7 along with various control constants and various maps. That is, in the controller 7, the computer unit functions as the controller 7 when the CPU executes a program stored in the ROM.

  Various sensors including a voltage sensor 21, a temperature sensor 22, a current sensor 23, and a capacitor voltage sensor 47 are connected to the input port of the controller 7. On the other hand, various control objects including the plus contactor 11, the precharge contactor 12, the minus contactor 14, and the DCDC converter 4 are connected to the output port of the controller 7. Note that, for example, the controller 7 can detect whether the communication line to which the operation permission signal is transmitted is disconnected by referring to the potential of the communication line. The DCDC converter 4 is configured to continue the operation when the communication line through which the operation permission signal is transmitted is disconnected.

  When an ignition switch (not shown) is turned on, the controller 7 starts processing, turns off the operation permission signal to stop the operation of the DCDC converter 4, turns on the precharge contactor 12 and the negative contactor 14, and turns on the capacitor. The precharge for charging 41 is started. Thus, the closed circuit when the precharge contactor 12 and the minus contactor 14 are turned on is called a precharge circuit.

  Then, for example, when the difference between the voltage of the high voltage battery 2 detected by the voltage sensor 21 and the voltage of the capacitor 41 detected by the capacitor voltage sensor 47 becomes equal to or less than a preset value, the controller 7 It is determined that charging has been completed. If it is determined that the precharge is completed, the controller 7 turns on the plus contactor 11, turns off the precharge contactor 12, turns on the operation permission signal, and starts the operation of the DCDC converter 4.

  The controller 7 includes a voltage adjustment unit 71 that adjusts the output voltage of the DCDC converter 4. The voltage adjustment unit 71 sets the output voltage of the DCDC converter 4 being precharged to a value such that the power supply to the low voltage system device 6 is only from the low voltage battery 3 and no output current flows from the DCDC converter 4, for example, The output voltage of the low voltage battery 3 is set to the same value.

  Specifically, when the ignition switch is turned on, the controller 7 turns off the operation permission signal to the DCDC converter 4 and turns on the precharge contactor 12 and the negative contactor 14. Moreover, the voltage adjustment part 71 transmits the voltage command signal to the DCDC converter 4 as 12V, for example.

  Then, the controller 7 monitors the completion of precharge. When it is determined that the precharge is completed, the controller 7 turns on the plus contactor 11, turns off the precharge contactor 12, and turns on and transmits an operation permission signal to the DCDC converter 4. Moreover, the voltage adjustment part 71 transmits the voltage command signal to the DCDC converter 4 as a normal value, for example, 14V.

  In this way, the voltage command signal to the DCDC converter 4 during precharging is set to a value such that the power supply to the low voltage system device 6 is only from the low voltage battery 3 and no output current flows from the DCDC converter 4. Therefore, even when the DCDC converter 4 starts its operation, the output current does not flow from the DCDC converter 4, so that the precharge can be completed early.

  A precharge control process performed by the control apparatus for an electric vehicle according to the present embodiment configured as described above will be described with reference to FIG. The precharge control process described below is executed when the ignition switch is turned on.

  First, the controller 7 turns on the minus contactor 14 (step S100). Next, the voltage adjustment unit 71 sets the voltage command signal to the DCDC converter 4 to 12 V, for example, for precharging (step S101). Next, the controller 7 transmits the operation permission signal to the DCDC converter 4 in an off state (step S102). Then, the controller 7 turns on the precharge contactor 12 (step S103).

  Next, the controller 7 determines whether or not the precharge is completed (step S104). When it is determined that the precharge is not completed, the controller 7 repeats the process of step S104 and waits for the completion of the precharge.

  On the other hand, when it is determined that the precharge is completed, the controller 7 turns on the plus contactor 11 (step S105). Next, the controller 7 turns off the precharge contactor 12 (step S106). Next, the voltage adjustment unit 71 sets the voltage command signal to the DCDC converter 4 to a normal value, for example, 14 V (step S107). Next, the controller 7 turns on and transmits an operation permission signal to the DCDC converter 4 (step S108), and ends the process.

The operation by such precharge control processing will be described with reference to FIG. The voltage command signal to the DCDC converter 4 is precharged 12V from the beginning.
First, when the negative contactor 14 is turned on at T1 and the precharge contactor 12 is turned on at T2, charging of the capacitor 41 is started, and the voltage of the capacitor 41 increases.

  Then, at the timing of T3, the difference between the voltage 200V of the high voltage battery 2 and the voltage of the capacitor 41 becomes equal to or less than a preset value, and it is determined that precharging is completed, and the plus contactor is turned on . Next, at T4, the precharge contactor 12 is turned off, and the voltage command signal to the DCDC converter 4 is changed from 12V to 14V. Next, at T5, the operation permission signal to the DCDC converter 4 is turned on, and the DCDC converter 4 starts operating.

  Thus, in this embodiment, since the voltage command signal to the DCDC converter 4 is set to the same voltage (12 V) as that of the low voltage battery 3 during the precharge, the low voltage system device 6 by the DCDC converter 4 is set. Current supply can be stopped. Accordingly, the current required for precharging is not consumed by the DCDC converter 4, and the precharge can be completed at an early stage to shorten the time required for vehicle travel.

  In the present embodiment, the voltage command signal to the DCDC converter 4 is set to the same voltage as that of the low-voltage battery 3 during the precharge, but the communication for transmitting the operation permission command during the precharge is performed. Only when the disconnection of the line is detected, the voltage command signal to the DCDC converter 4 may be set to the same voltage as the low voltage battery 3.

  Thus, since the voltage command signal to the DCDC converter 4 is set to the same voltage as the low-voltage battery 3 only when the disconnection of the communication line that transmits the operation permission command is detected during the precharge, the operation permission command is transmitted. Only when the communication line to be disconnected is disconnected, supply of current to the low voltage system device 6 by the DCDC converter 4 can be stopped, and even when the communication line for transmitting the operation permission command is disconnected, the precharge is completed early, The time until the vehicle can travel can be shortened.

  While embodiments of the invention have been disclosed, it will be apparent to those skilled in the art that changes may be made without departing from the scope of the invention. All such modifications and equivalents are intended to be included in the following claims.

DESCRIPTION OF SYMBOLS 1 Vehicle 2 High voltage battery 3 Low voltage battery 4 DCDC converter (voltage converter)
7 Controller 11 Plus Contactor 12 Precharge Contactor 13 Precharge Resistor 14 Negative Contactor 41 Capacitor 42 Transistor 46 Control Unit 47 Capacitor Voltage Sensor 71 Voltage Adjustment Unit

Claims (2)

A high voltage battery capable of storing high voltage power; and
A voltage converter for stepping down the output voltage of the high voltage battery;
A low voltage battery connected to the output terminal of the voltage converter;
A capacitor connected between the input terminals of the voltage converter;
A precharge circuit for precharging the capacitor;
An electric vehicle control device comprising:
A voltage adjustment unit for adjusting the output voltage of the voltage converter;
The voltage regulator is a control device for an electric vehicle that sets the output voltage of the voltage converter to the same voltage as that of the low-voltage battery during the precharge of the capacitor. The voltage converter is configured to be able to control operation or stop by an operation permission signal transmitted via a communication line,
2. The electric vehicle according to claim 1, wherein the voltage adjustment unit sets the output voltage of the voltage converter to the same voltage as that of the low-voltage battery only when the communication line to which the operation permission signal is transmitted is disconnected. Control device.

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