JPH06233402A - Drive control circuit for electric vehicle - Google Patents

Abstract

PURPOSE:To provide a drive control circuit for an electric vehicle of a three- phase inverter circuit type in which a fault of a power semiconductor switching element can be rapidly detected with high sensitivity. CONSTITUTION:A three-phase inverter 2 is energized by a battery 3 to combine three-phase AC voltages and to supply it to a three-phase motor 1. A controller (control circuit) 5 outputs a control voltage to control terminals of six power semiconductor switching elements (switches) 21-26 of the inverter, and intermittently controls them. The controller (malfunction detector) 5 has six switch malfunction detectors, each detector detects a potential difference between both main terminals of the switches 21-26 and individually detects a malfunction of each switch based on the detected potential difference. Since not entire current of the inverter 2 but excesses of the switches are individually detected, the malfunction of the switch can be accurately and rapidly detected.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a drive control circuit for an electric vehicle.

[0002]

2. Description of the Related Art Conventionally, as a drive control circuit for an electric vehicle such as a battery-powered forklift, a three-phase inverter circuit for supplying a three-phase AC voltage to a three-phase motor and a control circuit for controlling the three-phase inverter circuit are provided. It is known to be equipped. This three-phase inverter circuit consists of a bipolar transistor, SCR, power SIT, triac, I
An inverter formed by serially connecting a high-side switch and a low-side switch composed of a power semiconductor switching element such as a GBT is connected in parallel for three phases, and the output contacts of each inverter feed a three-phase motor. is doing.

The high-side main end of each high-side switch is connected to the high-side terminal of the battery, and the low-side main end of each low-side switch is grounded. The control circuit sequentially supplies the ON voltage to the control terminals of each switch. Conventionally,
In this kind of electric circuit, as a circuit abnormality countermeasure, a fuse or no-fuse breaker is installed in the high-side line that connects the battery and the high-side main end of each high-side switch, and they are blown or cut off by an excessive current. It is common to let the circuit open.

[0004]

However, in the drive control circuit of the electric vehicle of the three-phase inverter circuit type described above, it is important to detect the failure of the switch, that is, the semiconductor switching element for electric power, reliably and promptly and take countermeasures. However, in the above fuses and no-fuse breakers, it operates depending on whether the total current flowing through each power semiconductor switching element is greater than or equal to the reference value, so it is possible to operate them with the starting current of the three-phase motor. In order to prevent this, there is no choice but to set this reference value large, and there is a problem in detecting a failure of the power semiconductor switching element with high sensitivity and speed.

The present invention has been made in view of the above problems, and it is an object of the present invention to provide a drive control circuit of an electric vehicle of a three-phase inverter circuit type capable of detecting a failure of a power semiconductor switching element with high sensitivity and speed. , That is the problem to be solved.

[0006]

A controller for an electric vehicle according to the present invention comprises an inverter formed by connecting in series a high-side switch and a low-side switch, each of which is composed of a power semiconductor switching element, in parallel for three phases. Connected,
A three-phase inverter circuit that supplies a three-phase AC voltage from the output contact of each inverter to a three-phase motor, a control circuit that outputs a control signal to the control terminal of each switch, and an abnormality of the three-phase inverter circuit is detected. An abnormality detection circuit, wherein the abnormality detection circuit detects a potential difference between both main ends of the switches, detects an abnormality of each switch individually based on the detected potential difference, and outputs an abnormality signal. It is characterized by having six switch abnormality detecting units.

In a preferred mode, each of the switch abnormality detecting sections shuts off a control signal to a control terminal of the switch which has detected an abnormality. In a preferred embodiment,
The switch abnormality detection unit outputs the abnormal signal when an ON signal is input to the switch and a potential difference between both main ends of each switch exceeds a predetermined level.

[0008] In a preferred mode, the abnormality detection circuit includes a combined signal output unit for outputting a combined signal of the abnormal signals output from the switch abnormality detection units to the outside.

[0009]

The three-phase inverter circuit is fed from the battery, synthesizes the three-phase AC voltage, and feeds the three-phase motor. The control circuit outputs a control voltage to the control terminals of the six power semiconductor switching elements (switches) that form the three-phase inverter circuit, and controls the switches intermittently.

The abnormality detecting circuit, which is a feature of the present invention, comprises six switch abnormality detecting sections. Each switch abnormality detecting section detects a potential difference between both main ends of each switch, and based on each detected potential difference. Detect each switch abnormality individually. As described above, the drive control circuit for an electric vehicle of the present invention includes the six switch abnormality detecting units that individually detect an abnormality in each of the power semiconductor switching elements forming the three-phase inverter circuit. It is possible to detect an excess of the energization current of each power semiconductor switching element instead of an excess of the total current of the three-phase inverter circuit, and it is possible to set the reference value that determines whether it is excessive or not more strictly, with high accuracy. It is possible to quickly detect an abnormality in the power semiconductor switching element and take countermeasures against it.

[0011]

FIG. 1 shows an embodiment of a control device for an electric vehicle of the present invention. In FIG. 1, reference numeral 1 is a three-phase motor for running an electric vehicle, which has a Y-shaped three-phase coil 11 wound around a stator core (not shown). 2 is a three-phase inverter circuit, each of which is a high-side switch 2 composed of a power semiconductor switching element (IGBT in this case)
1 to 23 and low level switches 24 to 26, the high level switch 21 and the low level switch 24 form a U-phase inverter, and the high level switch 22 and the low level switch 2
5 constitutes a V-phase inverter, and the high side switch 23
And the lower switch 26 form a W-phase inverter.

The high-side main ends of the high-side switches 21-23 are connected to the high-side terminals of the battery 3, the low-side main ends of the low-side switches 24-26 are grounded, and the output contacts of each inverter are Each of them is connected to each terminal U, V, W of the Y-shaped three-phase coil 11. A traveling control microcomputer 4 has an I / O interface having a three-phase inverter circuit 2 through a controller (which constitutes a control circuit and an abnormality detection circuit according to the present invention) 5 which is a feature of this embodiment. Connected with. To explain further,
The controller 5 detects the potentials of the emitters and collectors (both main ends in the present invention) of all the switches 21 to 26, detects the abnormality of the potential between the emitters / collectors of the switches 21 to 26, and outputs the abnormality signal S. Output to the microcomputer 4. Further, the controller 5 receives the six pulse signals G1 to G6 from the microcomputer 4 and outputs the pulse signals to the gates (control terminals) of the switches 21 to 26.
To control voltages G1 'to G6'.

A block circuit diagram of the controller 5 is shown in FIG. The controller 5 is composed of six sub-controllers 51 to 56 and a NAND circuit 57 which have exactly the same configuration. The sub controller 51 includes comparators a and b, a NAND circuit c, and an AND circuit d. The operation of the sub controller 51 will be described below.

The comparator a is provided with a control voltage G1 for the switch 21 inputted from the microcomputer 4 and a predetermined reference voltage V.
If the G1 exceeds the reference voltage Vref1, the control voltage G1 is compared with the ref1 (which is set to + 5V here).
Outputs a high level H on the assumption that the voltage has turned on. The comparator b has a collector voltage V of the switch 21.
1 is compared with a predetermined reference voltage Vref2, and if V1 exceeds the reference voltage Vref2, it is determined that the collector voltage V1 has become large and a high level H is output. Here, the reference voltage Vref2 is a reference voltage generated inside the sub-controller 51 having the emitter voltage V7 of the switch 21 as the internal ground potential, and is set to + 5V when the emitter voltage V7 is 0V. There is.

The NAND circuit c outputs an abnormal signal S1 which is a logical product signal of the comparators a and b. Therefore, in the abnormal signal S1, the control voltage G1 becomes the ON voltage,
Moreover, it becomes a low level (abnormal state) only when the voltage drop between the emitter and collector of the switch 21 is +5 V or more. The AND circuit d is a control voltage G1 'composed of a logical product signal of the output signal of the comparator a and the output of the NAND circuit c.
Is output to the gate of the switch 21. Therefore, the control voltage G1 'is the output signal of the comparator a as the control voltage G1' only when the output of the NAND circuit c is at a high level (normal state), that is, when the voltage drop between the emitter and the collector of the switch 21 is + 5V or less. The signal is output to the gate of the switch 21 so that the switch 21 can be turned on and off. That is,
The AND circuit d has an interlock function.

Now, when the emitter / collector of the switch 24 is short-circuited, when the switch 21 is turned on, a large current flows between the emitter / collector of the switch 21 and the switch 21 is also destroyed. As a result, the battery 3 is short-circuited. Due to the switches 21 and 24, the short-circuited state is completely generated. In this embodiment, the current increase between the emitter / collector of the switch 21 is determined by whether the voltage drop between the emitter / collector is equal to or larger than a reference value. When the voltage drop is equal to or larger than the reference value, an abnormal signal S1 is generated as an abnormal state. At the same time as outputting, the output of the ON voltage (high level voltage) to the gate of the switch 21 is cut off and the short circuit current is cut off.

Therefore, when the magnitude of the total current flowing out from the battery 3 is detected, the normal current value of one of the switches 21 to 26 is normal because of the overlap (often occurring) of the inverter currents. Since it is larger than the current value, the reference current value, that is, the threshold value for determining abnormality / normality must be set to a large value. However, if the excessive current of each of the switches 21 to 26 is individually detected as in this embodiment, The abnormality can be discriminated when the current value is small, and the abnormality can be detected quickly with high accuracy.

Further, according to the present embodiment, even if a failure other than a short circuit of the switch 24, that is, if the switch 21 does not conduct despite the application of the ON voltage, it can be detected by the same principle and an abnormal signal is issued. When the coil of the three-phase motor 1 is short-circuited, the insulation between the gate of the switch 21 or 24 and the collector or the emitter can be detected, and the abnormality can be detected with a simple circuit configuration.
It can be switched off.

The sub-controllers 52 to 56 have the same structure as the sub-controller 51, and only the input / output signals are different, and therefore the description thereof will be omitted. The abnormal signals S1 to S6 (abnormal at low level) output from the sub-controllers 51 to 56 are combined by the NAND circuit 57 and output to the microcomputer 4 as the abnormal signal S of the three-phase inverter circuit 2. That is, the NAND circuit 57 uses the abnormal signal S1.
If any one of to S6 is low level (abnormal), it becomes high level (abnormal). That is, according to this embodiment, the failure of each of the switches 21 to 26 is the same kind of failure, and
If any one of the switches has a failure, it is necessary to take the same countermeasures. Therefore, the abnormal signals S1 to S6 are collectively output to the microcomputer 4, so that the I / O interface of the microcomputer 4 can be simplified and downsized. There is. Of course, if the circuit configuration is changed, the NAND circuit (the combined signal output section in the present invention)
It is also possible to change 57 to an OR circuit.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an example of a drive control circuit for an electric vehicle according to the present invention.

FIG. 2 is a block circuit diagram of a controller 5 shown in FIG.

[Explanation of symbols]

 1 Three-Phase Motor 2 Three-Phase Inverter Circuit 5 Controller (Control Circuit, Abnormality Detection Circuit) 21-23 High-Level Switch 24-26 Low-Level Switch 51-56 Sub Controller (Switch Abnormality Detection Section) 57 NAND Circuit (Unified Signal) Output part)

Claims (4)

[Claims] 1. An inverter formed by serially connecting a high-side switch and a low-side switch, each of which is composed of a power semiconductor switching element, is connected in parallel for three phases, and three phases are connected from an output contact of each inverter. A three-phase inverter circuit that supplies an AC voltage to a three-phase motor, a control circuit that outputs a control signal to the control terminal of each switch, and an abnormality detection circuit that detects an abnormality of the three-phase inverter circuit, wherein the abnormality The detection circuit includes six switch abnormality detection units that detect a potential difference between both main ends of each switch, individually detect an abnormality of each switch based on each detected potential difference, and output an abnormality signal. A drive control circuit for an electric vehicle characterized by the above. 2. The drive control circuit for an electric vehicle according to claim 1, wherein each of the switch abnormality detection units cuts off a control signal to a control terminal of the switch that has detected an abnormality. 3. The switch abnormality detecting unit outputs the abnormal signal when an ON signal is input to the switch and a potential difference between both main ends of each switch exceeds a predetermined level. A drive control circuit for an electric vehicle according to claim 1. 4. The drive control circuit for an electric vehicle according to claim 1, wherein the abnormality detection circuit includes a federation signal output unit that outputs a federation signal of the abnormality signals output from the switch abnormality detection units to the outside. .