JPS604671B2 - High power transistor chopper monitoring device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a monitoring device for a high power transistor chopper which detects a failure in the high power transistor chopper and disconnects its main power supply.

In general, in high-power transistor transistors used in the main power supply of electric vehicles that use DC motors as their drive source, the high-power transistor that switches the main circuit burns out, causing a full conduction accident. If this occurs, the DC motor will accelerate, resulting in a very dangerous situation.

The present invention has been made with these points in mind, and is a high-power transistor switch that constantly monitors the switching state of the high-power transistor, detects when a failure occurs, and immediately shuts off the main circuit. The purpose of this project is to provide a monitoring device for

The monitoring device for a high-power transistor chopper according to the present invention has a control signal for the high-power transistor in a range of several milliseconds to several tens of milliseconds.
An OFF signal is superimposed at intervals of 0 s to cause the capacitor to be charged and discharged in accordance with the switching command according to the ON voltage detection signal of the high power transistor, and the level of the charging voltage of the capacitor is detected and the charging is performed. When the voltage exceeds a preset voltage value, an off command is issued to a switch provided in the main circuit. DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

In the high power transistor chopper monitoring device according to the present invention, as shown in FIG. , a flywheel diode D is provided in parallel with the DC motor M, a series circuit of a surge absorbing resistor R and a capacitor C2 is provided in parallel with the high power transistor GTR), and the current setting device 1 provides from the accelerator signal and the main circuit to the shaft SH and the first isolated amplifier A.
A matching circuit 2 matches the current feedback signal detected through the M circle, and the difference signal and the signal generated from the triangular wave generator 3 are compared by a comparator CMP, and the resulting pulse signal is In a high-power transistor chopper consisting of a control circuit that sends a control command to a high-power transistor GTR through a second isolation amplifier AMP2, a signal is sent to the output side of the comparator CMP via an AND circuit AND at intervals of several ms to several tens of hs. an off signal generator 4 that superimposes a pulse-like off signal with It is constructed by providing a shroud disconnection operation circuit 6 for opening the main switch CB provided in series in the circuit.

Further, as shown in FIG. 2, the failure detection circuit 5 includes a charging operation circuit 51 that controls opening and closing of the switch CB2 in response to an off signal, and a battery B that is turned on when the switch C& is closed. As a result, the on-voltage of the failure detection capacitor C3 (hereinafter abbreviated as capacitor C3) that is charged through the constant current circuit 52 and the large-power transistor GTR in the main circuit is detected, and the large-power transistor is turned off. A main circuit voltage detector 53 that outputs an output when the voltage rises, a charging control switch SW whose contacts are opened in response to the detection signal to form a discharge circuit for the capacitor C3, and a switch SW that controls the terminal voltage of the capacitor C3. A level detector 54 detects the level and issues a control command to the shear cutting operation circuit 6.

The operation of the high-power transistor chopper monitoring device according to the present invention configured as described above will be described below.

First, the current actually flowing in the main circuit is comparatively controlled in accordance with the accelerator signal output from the current setting device 1, and the conduction rate is appropriately adjusted in the comparator CMP by the signal from the triangular wave generator 3. The pulse output of the comparator CMP is sent to the base of the high power transistor GTR in the main circuit to perform its switching, but at this time, the off signal from the off signal generator 4 is sent to the pulse output of the comparator CMP through an AND circuit AND. Superimposed.

This off signal is a pulse-like signal with an interval of several ms to several tens of hs, and by adding this off signal to the control signal of the high power transistor GTR, it is possible to prevent any failure from occurring within the control circuit system. High power transistor GTR is prevented from becoming fully conductive. Note that if the lower limit of the off signal time interval is too small, switching loss will occur in the chopper main circuit, and if the upper limit is too large, the DC motor M will be accelerated in the event of a failure, resulting in a dangerous situation. , is set within the range mentioned above. At the same time, the off signal from the off signal generator 4 is transmitted to the failure detection circuit 5.
The signal is sent to the charging operation circuit 51, which keeps the switch C& closed for a period of several milliseconds to several tens of seconds. However, in the case of a failure in the control circuit, for example, when the main transistor burns out, the switch C The main circuit voltage detector 53 will not operate unless the high power transistor OTR continues to be on and the voltage rises, and the switch SW will not be closed, so the capacitor C3 will not be discharged during that time.

Then, the capacitor C3 is further charged by the next off signal, and the capacitor C3
voltage increases. In this case, the charging voltage of the capacitor C3 is compared with a reference voltage value preset in the level detector 54, and when the charging voltage exceeds the reference voltage value, it is assumed that an accident has occurred in the main circuit and the circuit is shut off. Operation circuit 6
A command to disconnect the main circuit is sent to the main circuit, thereby opening the main switch CB in the main circuit and forcibly disconnecting the battery B from the main circuit.

In addition, during normal operation of the main circuit, the high power transistor GTR is turned off before the charging voltage of the capacitor C3 reaches the reference voltage set in the level detector 54, so that the detection output of the main circuit voltage detector 53 is output. Then, switch SW is closed and a discharge circuit for capacitor C3 is formed. At this time, the capacitor C3 is turned off for several ms by the off signal.
It is designed to be completely discharged at intervals of several tens of seconds. As described above, in the high power transistor chopper monitoring device according to the present invention, the main switch CB is opened at the same time as an accident occurs in the main circuit, so that the main switch CB is opened before the current flowing in the main circuit becomes too large. Therefore, the current capacity of the main switch CB is not required to be very large. On the other hand, since the main switch CB is opened when the main circuit current becomes excessive, an arc is generated and the main circuit is no longer disconnected. It becomes possible to quickly and reliably disconnect the main circuit when an accident occurs. It should be noted that the monitoring device for a high power transistor chopper according to the present invention is not limited to that of the embodiment described above, and for example, the operation circuit 51 in the failure detection circuit 5
Needless to say, the design can be changed as appropriate, such as by using the output of the second isolation amplifier AM2 in the control circuit instead of the off signal as the input command.

As described above, in the monitoring device for a high-power transistor chopper according to the present invention, in a chopper that uses a battery as the main power source and whose main circuit is switched by a high-power transistor, a superimposed signal is an off signal generator that generates an off signal with an interval of several ms to several tens of hs; and a fault detection capacitor is charged when the off signal of the high power transistor is turned off, and a fault detection capacitor is charged when the high power transistor is off. A failure detection circuit detects whether an accident has occurred in the main circuit by discharging a detection capacitor and detecting the level of its charging voltage, and opens the main switch installed in the main circuit in response to the failure detection signal. It is constructed by providing a cutting and cutting operation circuit, and even if various causes of failure occur in the chopper circuit, the main circuit can detect it and quickly and reliably cut or break the main circuit current. This makes it particularly advantageous as a protection device for electric vehicles whose main drive source is such a high-power transistor chopper.

[Brief explanation of the drawing]

FIG. 1 is an electrical wiring diagram showing a monitoring device for a high-power transistor chopper according to an embodiment of the present invention, and FIG. 2 is an electrical wiring diagram showing an example of the configuration of a failure detection circuit in the same embodiment. 1...Current setting device, 3...Triangular wave generator,
4... Off signal generator, 5... Failure detection circuit, 51... Charging operation circuit, 52...
... Constant current circuit, 53... Main circuit voltage detector,
54...Level detector, 6...Shrinking operation circuit. Figure 1 Bag Figure 2

Claims (1)

[Claims] 1. A main switch, a DC motor, and a high-power transistor are connected in series to the battery of the main power source, and a smoothing capacitor is connected in parallel to the battery, a flywheel diode is connected in parallel to the DC motor, and a flywheel diode is connected in parallel to the high-power transistor. For example, a main circuit that connects a series circuit of a resistor and a capacitor for surge absorption; a difference signal between the current feedback signal detected from this main circuit and the accelerator signal set by the current setting device; and a triangular wave generator. inputs the signal from the triangular wave generator into a comparator, adjusts the conductivity of the difference signal by the signal from the triangular wave generator, and uses the pulse signal output from the comparator as a control command for switching of the high power transistor. an off signal generator that superimposes an off signal of several ms to several hundreds of ms on the output pulse signal from the comparator via an AND circuit; while there is no off signal from this off signal generator, a charging operation circuit that charges the failure detection capacitor from the battery of the main power supply via a constant current circuit; and a charging operation circuit that charges the failure detection capacitor when it is detected that the high power transistor of the main circuit is turned off and the voltage has increased. Comparing the charging voltage of the main circuit voltage detector to be discharged and the charging voltage of the failure detection capacitor with a preset reference voltage value, and detecting that the charging voltage of the failure detection capacitor has exceeded the reference voltage value. a failure detection circuit comprising a level detector that detects a failure in the main circuit and outputs a command to shut down the main circuit;
A monitoring device for a high-power transistor chopper, comprising a shield disconnection operation circuit that releases a main switch of the main circuit in response to a shield disconnection command from the failure detection circuit.