JP3382110B2 - Control device for electric vehicle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an electric vehicle. 2. Description of the Related Art A control device for an electric vehicle has an inverter as one of its components, and the inverter has a large-capacity smoothing capacitor in parallel with an input line on a power supply side (main power supply side). IGBTs (Insulated Gate Bipolar Transistors) are usually composed of a plurality of switching elements.
sistor) and transistors are used. Then, a drive circuit is provided corresponding to the element, and the drive circuit operates each switching element in accordance with a drive command signal from the control circuit to drive and control the motor. When such a motor drive control system control device is used in an electric vehicle or the like, an ignition switch is turned on, and a power supply voltage is supplied to each of a drive circuit and a control circuit to perform the above-described control. However, when the ignition switch is turned off, the drive voltage to the switching element (the drive voltage generated based on the drive power supply, or the gate-emitter voltage in the case of IGBT) disappears while being stored in the large-capacity smoothing capacitor. Therefore, the switching element may be turned on due to noise or the like.
If the switching element is turned on, the electric charge remaining in the smoothing capacitor without being discharged may flow as a large current to the switching element, and the switching element may be damaged. [0004] Even when the charge of the smoothing capacitor is discharged, if a permanent magnet motor is used, the smoothing capacitor is charged by the back electromotive force generated by the external force, and the switching element is damaged in the same manner as described above. There is a fear. In order to solve the above-mentioned problem, Japanese Patent Laid-Open No. 7-194184 discloses a protection circuit for turning off a switching element by detecting that a power supply voltage to a drive circuit for controlling the switching element is cut off. Is disclosed. [0005] However, in the prior art, as shown in FIG. 3, the protection circuit 18 for the switching element (IGBT 11) when the ignition switch is turned off and the drive power supply voltage is reduced, as shown in FIG. If the protection circuit 18 breaks down and the contacts of the protection circuit 18 are constantly short-circuited, the protection circuit 18 is provided at the subsequent stage of the drive circuit 3 so that a command to turn on the IGBT 11 is issued. When a signal is input, the drive circuit 3
Although an attempt is made to pass a current to the BT11, all of the current is consumed by the protection circuit 18, and the power consumption of the resistor R and the transistor Tr7 increases. On the other hand, when a command signal for turning off is input, The power consumption of the resistor R and the transistor Tr8 increases, which may cause a failure in the drive circuit 3 itself. If only one of the plurality of protection circuits 18 fails, no current flows through the failed circuit, so that an unbalanced switching operation occurs between the IGBTs 11 and the flowing current does not become an alternating current. The state of the open-phase operation occurs, and the generated torque of the motor becomes intermittent. This leads to deterioration of the ride comfort of the occupant. Therefore, an object of the present invention is to provide a highly reliable switching circuit that does not cause a secondary failure in other circuits even if a protection circuit for a switching element fails, and that avoids imbalance in switching operation. An object of the present invention is to provide a control device for an electric vehicle. [0007] The feature of an electric vehicle control device according to the present invention that achieves the above object is that an inverter configured by a switching element to control a main power supply and a drive power supply are provided. A control circuit for driving the switching element, a control circuit for outputting a drive command signal to the drive circuit, and a switch for turning on / off power supply to the control circuit; Voltage detecting means for detecting whether the power supply voltage on the power supply side is higher or lower than a predetermined value and outputting a high / low signal, on / off detecting means for detecting an on / off signal of the switch, and based on the high / low signal and the on / off signal. Switch control means for controlling the supply of the drive power supply, and when the ON signal is detected, the drive control means is provided. The power supply of the live power supply is executed, the supply of the drive power is continued when the off signal and the high signal are detected, and the supply of the drive power is stopped when the off signal and the low signal are detected. Is to do. According to the present invention, the protection control of all the switching elements is executed by the collective power supply control of the protection circuit. Therefore, even if the protection circuit for the switching element fails, the secondary circuit is not connected to other circuits. Failure is not induced, and unbalance of the switching operation is avoided. Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a circuit diagram showing an electric vehicle control device according to one embodiment of the present invention. The configuration of the control device for an electric vehicle of the present embodiment is shown from an electric circuit. The control device for an electric vehicle shown in the figure includes an inverter 1, a drive circuit 3, a control circuit 4, an ignition switch 13, a voltage detection circuit 6, and a switch circuit 1.
And 0. The control device for the electric vehicle may or may not include the ignition switch 13 and the relay 14. The detailed configuration and operation of the control device for an electric vehicle will be described below. Control device for electric vehicle
The control device (hereinafter, referred to as a control device) converts a DC voltage of a battery 5 as a main power supply into an AC voltage by using the inverter 1, and executes drive control of the motor 2. The motor 2 of the present embodiment is a three-phase AC motor. The induction type or the permanent magnet type can be used. The inverter 1 of this embodiment has a total of six IGBTs 11 corresponding to each phase of the motor 2. The relay 14 is interposed between the battery 5 and the inverter 1 and is turned on when the control circuit 4 starts operating, and turned off when the control circuit 4 stops operating. It is. Note that the inverter 1 having a configuration in which the smoothing capacitor 7 and the discharge resistor 15 are not wrapped may be used, and the relay 14 may be used also as another relay or a switch. The input side (main power supply side) of the inverter 1 is generally connected to a smoothing capacitor 7 for suppressing a change in input voltage, and is connected in parallel with the smoothing capacitor 7 when the relay 14 is turned off. A discharge resistor 15 for discharging the charge stored in the capacitor is connected. The drive circuit 3 is connected to the gates of all the IGBTs 11 and based on a drive command signal from the control circuit 4 and a drive voltage generated from a drive power supply supplied from a switch circuit 10 to be described later. 3 is all IGB
The driving of the switching of T11 is controlled. Note that the smoothing capacitor 7 and the discharge resistor 15 may be separated and independent from the inverter 1. Further, a voltage detecting circuit 6 as a voltage detecting means detects whether the voltage of the smoothing capacitor 7 in the inverter 1, that is, the power supply voltage on the main power supply side of the inverter is higher or lower than a predetermined value. And the voltage detection circuit 6
Is output to the switch circuit 10. At the same time, an on / off signal of the ignition switch 13 as a “switch” (that is, the sub-battery 12
Power ON / OFF signal) is input to the switch circuit 10,
The data is also input to the control circuit 4. A switch circuit 10 serving as both an on / off detection means and a switch control means inputs and determines an on / off signal from an ignition switch 13 and a high / low signal from a voltage detection circuit 6, and determines a drive signal. The power supply of the sub-battery 12 to the circuit 3, that is, the supply of the drive power supply is controlled at once (collectively). That is, the operation of the drive circuit 3 is controlled. In other words, the power of the sub-battery 12 is supplied as necessary (when a predetermined condition is satisfied) by means (an alternative route method) that does not depend on (cooperate with) the ignition switch 13 only. This is to avoid an “unstable state” that occurs because the drive voltage to the IGBT 11 when the switch 13 is turned off disappears. Note that the battery 5 and the sub-battery 12 may be the same. That is, the electric vehicle control device according to the present invention shown in FIG. 1 is characterized in that the power supply to the drive circuit 3 does not depend on (cooperate with) only the ignition switch 13 and the ignition switch 13 is turned off. Even when the voltage applied to the switching element of the inverter 1 is high, the power supply is continued, and when the voltage is low, the power supply is stopped. Alternatively, a protection circuit is provided as a power supply control means including a voltage detection circuit 6 as a voltage detection means and a switch circuit 10 serving as both an on / off detection means and a switch control means, and the ignition switch 13 is turned off. However, if the "predetermined voltage condition for determining that the switching element is not damaged" is not satisfied, drive power is supplied to the drive circuit 3 to maintain the operation of the drive circuit 3 and ensure that the IGBT 11 is turned off. It is characterized by maintaining. To execute protection control of all switching elements at once,
It can be said that it is desirable to provide the protection circuit in a stage preceding the drive circuit. In other words, the control device for an electric vehicle is characterized in that voltage detection means for detecting whether the power supply voltage on the main power supply side of the inverter is higher or lower than a predetermined value and outputting a high / low signal, and turning on / off the ignition switch ON / OFF detection means for detecting a signal, and switch control means for controlling whether or not to continue power supply for controlling a switching element based on a high / low signal and an ON / OFF signal at a stage preceding a power supply circuit of a drive circuit, and Even if the ignition switch is turned off, if the power supply voltage on the main power supply side of the inverter is higher than a predetermined value, the switch control means is closed and power supply to the drive circuit is continued. With the configuration having the above characteristics, even if the ignition switch is turned off and the control circuit stops operating,
The switch circuit is closed and the power supply to the drive circuit is continued until the voltage applied to the switching element, that is, the storage voltage of the smoothing capacitor of the inverter becomes lower than the voltage that causes the switching element to be destroyed. Is maintained in the off state, the "unstable state" is avoided, and the switching element is reliably protected. Also, even if the switch circuit fails, the secondary failure such as the drive circuit failure will not be induced.
The operation between the switching elements does not become unbalanced, and the protection circuit has high reliability. FIG. 2 is a diagram showing a protection circuit according to one embodiment of the present invention. FIG. 1 shows a configuration of a protection circuit as a power supply control unit including a voltage detection circuit 6 and a switch circuit 10. The stored voltage of the smoothing capacitor 7 is divided by the resistors 21 and 22 and input to the “+” terminal of the operational amplifier 24. The reference voltage 2 is applied to the “−” terminal of the operational amplifier 24.
3 is connected, and the value of the reference voltage 23 is "equivalent to the + terminal voltage" when the IGBT 11 is at a sufficiently low voltage that does not destroy it.
Is set to Therefore, if the smoothing capacitor voltage is high, “High” is output, and if it is low, “Low” is output. The output of the operational amplifier 24 is input to the base of the transistor 30 via the resistor 25 and the diode 26. An on / off signal of the ignition switch 13 is similarly input to the transistor 30 via the resistor 27 and the diode 28. Therefore, as a narrow definition, it can be said that the on / off detection means is a means including the resistor 27 and the diode 28. A resistor 29 is connected between the base and the emitter of the transistor 30. The collector of the transistor 30 is connected to the coil 31. The contact 32 is driven by the coil 31. In the above configuration, when the ignition switch 13 is turned on, the transistor 3 is connected via the resistor 27.
Since 0 is turned on, a current flows through the coil 31 and the contact 32
Turns on, the drive circuit 3 starts operating, and the IGBT 1
1 is turned off. Subsequently, since the ignition switch 13 is turned on and the relay 14 is turned on, a voltage is applied to the smoothing capacitor 7 and the output of the operational amplifier 24 of the voltage detection circuit 6 becomes “High”. In this state, when the ignition switch 13 is turned off next, the control circuit 4 functions and the relay 14 is turned off. However, while the voltage of the smoothing capacitor 7 is higher than a predetermined voltage, the operation of the operational amplifier 24 is stopped. Since the output is “High”, the transistor 30 and the contact 32 are kept on, the operation of the drive circuit 3 is maintained, and the IGBT 1
The off state of No. 1 is also maintained. When the voltage of the smoothing capacitor 7 is reduced by discharging by the discharge resistor 15, the operational amplifier 24 outputs "Low" to turn off the transistor 30 and also the contact 32 to turn off. Stops,
At this point, the maintenance of the off state of the IGBT 11 is released. In other words, until the voltage applied to the IGBT 11 becomes a low voltage that does not cause destruction,
Since the off state of 11 is reliably maintained, it can be said that a highly reliable control device for an electric vehicle is provided. Further, as described above, if the switch circuit as the protection circuit is provided in the preceding stage of (the power supply circuit of) the drive circuit, even if the switch circuit fails, the secondary failure may occur. The failure of the drive circuit and the like (including the inverter at the subsequent stage of the drive circuit) is not induced.
Further, since a protection circuit is not provided for each switching element and the operations of all the switching elements are stopped at once, it is possible to avoid a deterioration in ride comfort of the occupant due to an operation imbalance. According to the present invention, since the protection circuit is provided in the preceding stage of the drive circuit and the protection control of all the switching elements is executed collectively, even if the protection circuit fails, other circuits can be provided. For example, a secondary failure is not induced, and unbalance of the switching operation of the switching element is avoided. In other words, there is an effect that a highly reliable electric vehicle control device can be obtained.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit diagram showing an electric vehicle control device according to one embodiment of the present invention. FIG. 2 is a diagram showing a protection circuit of one embodiment according to the present invention. FIG. 3 is a diagram showing a conventional protection circuit. [Description of Signs] 1 ... Inverter, 2 ... Motor, 3 ... Drive circuit, 4 ...
Control circuit, 5: Battery, 6: Voltage detection circuit, 7: Smoothing capacitor, 10: Switch circuit, 11: IGBT, 12: Sub-battery, 13: Ignition switch, 14: Relay, 15: Discharge resistance, 18: Protection circuit , 21, 22, 25, 27, 29 ... resistance, 23 ... reference voltage, 24 ... operational amplifier, 26, 28 ... diode, 30 ... transistor, 31 ... coil, 32 ... contact.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hiroshi Katada 2520 Ojitakaba, Hitachinaka-shi, Ibaraki Hitachi, Ltd.Automotive Equipment Division (72) Inventor Tetsuya Yokoyama 2520 Ojitakaba, Hitachinaka-shi, Ibaraki Hitachi, Ltd. Manufacturing Company Automotive Equipment Division (72) Inventor Yasuo Matsunaga Nissan Motor Co., Ltd. 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Prefecture (56) References JP-A-7-7807 (JP, A) JP-A-3-273816 ( JP, A) JP-A-2-269403 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B60L 3/00 H02H 7/122 H02M 7/48 H02P 7/63 302

Claims (1)

(57) [Claim 1] An inverter configured by a switching element to control a main power supply, a drive circuit to receive a drive power supply to drive and control the switching element, and to the drive circuit In a control device for an electric vehicle including a control circuit for outputting a drive command signal and a switch for turning on and off a power supply to the control circuit, it is determined whether a power supply voltage on a main power supply side of the inverter is higher or lower than a predetermined value. Voltage detecting means for detecting and outputting a high / low signal; on / off detecting means for detecting an on / off signal of the switch; and switch control means for controlling supply of the drive power based on the high / low signal and the on / off signal. When the ON signal is detected, the drive power supply is executed, and when the OFF signal and the high signal are detected, The control device for an electric vehicle, wherein the supply of the drive power is continued, and the supply of the drive power is stopped when the off signal and the low signal are detected.