JPH0792222A - Circuit for detecting deterioration of thyristor and ignition device of internal combustion engine using the circuit - Google Patents

Abstract

PURPOSE:To detect the deterioration of a thyristor in an early stage with a simple constitution thereby to maintain various kinds of electronic and electric devices, by detecting the deterioration of the thyristor from logic output of a circuit for detecting a gate signal and a circuit for detecting a gate voltage. CONSTITUTION:When an electricity from a power source PW is applied between an anode A (+) and a cathode K (-) of a thyristor S, a blocking function of the thyristor works before a predetermined voltage is achieved, and the thyristor is turned conductive when it is not lower than the predetermined voltage. However, if the thyristor S starts to deteriorate, a leak current is considered to flow out from a PN junction J2 which maintains a with stand voltage before the thyristor reaches the predetermined voltage, that is, a current equivalent to the leak current is considered to be generated through an internal resistance Tgamma. A voltage between a gate G and the cathode K based on the leak current is detected by a detecting circuit GK. When a required voltage is brought about between the gate G and cathode K while the gate signal is stopped (not generated yet), if a logic of a logic circuit AND is satisfied to generate a logic signal, the deterioration of the thyristor S can be detected in an early stage.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a deterioration determining circuit for a thyristor (rectifier with control pole) and various electronic circuits to which this circuit is applied, and more particularly to an electronic ignition device for an internal combustion engine.

(2)

2. Description of the Related Art As is well known, thyristors are used as various switch devices for rectification or for controlling various electronic devices for phase control. The thyristor concerned generally has an anode electrode (+) and a cathode.
It has a function of applying a (-) potential to the gate electrode and applying a gate voltage between the gate electrode and the cathode electrode to shift from the forward blocking to the conductive state. Although the timing of applying the gate voltage (signal) varies depending on various uses, it is a normal state that the predetermined forward blocking characteristic is maintained until the arrival of the gate signal. However, characteristics may deteriorate due to long-term use, etc., and the predetermined forward blocking function may not be maintained, resulting in a short circuit or the like.

[0003]

Problems of the Prior Art When a short-circuit accident or the like occurs, it becomes a big problem that damages various parts, loads, etc. which form an electric circuit together with a thyristor. For this reason, conventionally, there is no easy method or circuit for judging the deterioration state of the thyristor at an early stage, and various protection circuits are assumed to be attached to the specified application in consideration of deterioration or the like.

[0004]

It is an object of the present invention to provide an easy thyristor deterioration determination circuit which solves the above problems, and various electronic equipments which can utilize this circuit, especially an ignition device for an internal combustion engine, which is compact, economical and reliable. For the purpose of improvement.

[0005]

SUMMARY OF THE INVENTION The present invention is a power supply for supplying a direct current (or alternating current) between the anode and cathode of a thyristor, and a gate signal is intermittently applied to the thyristor. A gate circuit, a gate signal detection circuit for detecting a signal stop of the gate circuit, and a gate of the thyristor.
A gate voltage detecting circuit for detecting the voltage between the gate and the cathode is provided, and the thyristor is judged to be inferior (3) by the logical outputs of the gate signal detecting circuit and the gate voltage detecting circuit. It is characterized by having done.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a circuit diagram of an embodiment of the present invention, in which S is an equivalent structure diagram of a thyristor, A is an anode electrode, K is a cathode electrode, G is a gate electrode, and GC is Game of thyristor S
The gate electrode G is a gate circuit for transmitting an intermittent gate signal,
D0 is a gate protection diode, GK is a voltage detection circuit between the gate G and cathode K of the thyristor, and IN is a gate for detecting the stop (not occurring) of the gate signal. A signal detection circuit, AND is a circuit that takes the logic of both detection circuits GK and IN, and PW is a DC or AC power supply.

Next, the operation will be described with reference to FIG. First, FIG. 2 (a) shows the forward blocking characteristic of the thyristor, in which the anode A of the thyristor S is (+) and the cathode is
It shows that when the power PW is applied to the terminal K (−), it has a blocking function up to a predetermined voltage, and when it becomes a voltage higher than a certain voltage (VBO), it self-ignites and becomes conductive, and a current IA flows. . When the thyristor begins to deteriorate in place, the thyristor S shown in FIG.
In the cross-sectional view of Fig. 3, it is predicted that the leakage current will flow from the PN junction J2 that maintains the withstand voltage before reaching the predetermined voltage (VB0). This is equivalent to the internal resistance r (a)
It is considered that an electric current is generated as shown by the dotted line in the figure. Therefore, in the present invention, the voltage between the gate and the cathode based on this leakage current is detected by the detection circuit GK. (FIG. 2 (b)) Next, FIG. 2 (c) shows the gate voltage waveform (intermittent) of the gate circuit GC.
Indicates. Further, FIG. 2D shows an inverted waveform of the gate voltage due to the inverter IN. That is, according to the present invention, when a required voltage is generated between the gate and the cathode in a state where the gate signal is stopped (not generated), the logic of the logic circuit (AND) is established, and FIG. The early deterioration of the thyristor is determined by generating the logic signal (e).

Next, an application example of an electronic circuit using the judgment circuit of the present invention will be described. First, (4) FIG. 3 is a circuit diagram of an ignition device for an internal combustion engine of a general two-wheeled vehicle, which is called a capacitor charge / discharge ignition device.
D / D boosts the battery-BAT voltage. DC / D
C converter, D1 is a rectifying diode, C1 is a capacitor for storing this charge, PC is a pulser, GC is a gate circuit, S1 is a thyristor, IG is an ignition coil, and SP is a spark plug. This operation is performed by the D / D converter.
The voltage boosted by the capacitor is rectified by the diode D1 and charged in the capacitor C1. On the other hand, an ignition signal synchronized with the engine is generated from the pulsar PC, is given to the thyristor S1 through the gate circuit GC, and the electric charge of the capacitor C1 is discharged to the ignition coil IG through the thyristor S1. Then, the spark plug is ignited.

As described above, ignition must always be performed in synchronization with the pulse signal. However, in the past, there was a possibility that the thyristor would turn on regardless of the pulser signal due to deterioration of breakdown voltage of the thyristor, causing damage to the engine or reverse rotation. For this reason, a method has been taken in which a plurality of thyristors are connected in series to prevent the breakdown voltage from deteriorating.

FIG. 4 shows an embodiment of the present invention, and the same reference numerals as those in the conventional example show the same parts. In addition, AMP is an operational amplifier, (gate / cathode voltage detector) D2 is a diode.
IN, INV are inverters, (gate signal detector) AN
D is an AND gate and Q1 is a transistor. The operation of this circuit operates as follows. First, in a normal state, each time the pulser signal arrives, the thyristor S1 is turned on and ignition is continued. The operation waveforms of the respective parts of the thyristor at this time are as shown by the solid lines in FIGS. Next, the breakdown voltage of the thyristor is as shown by the dotted line in FIG.
If it is deteriorated, the waveform of each part of the thyristor becomes like the dotted line of (b) to (d) in the figure. But in this case
With the rise of the anode voltage VAK, the gate of the thyristor (5) The voltage VGK also rises slightly (0.3V to 0.4V), so after increasing this voltage by AMP, the pulser signal is After confirming that it is not present (the AND of the PC signal and the AMP output is taken), the transistor-Q1 is turned on. As a result, D /
The D converter stops oscillating, and the thyristor anodic voltage VAK stops rising at the point of (a) in FIG. 5 (a) to prevent erroneous ignition due to deterioration of withstand voltage.

In the above embodiment, DC is used as the power source of the ignition device.
Although the example using the / DC converter has been described, the present invention is also applicable to an example using a generator as a power source as shown in FIG. FIG. 6 is a circuit diagram of another embodiment of the present invention.
XT is a generator coil of the generator, PC is a pulsar coil built in this generator, and S2 and S2 'are thyristors. The operation of this circuit is such that the capacitor C1 is charged through the diode D1 by the half cycle output of the AC output of the generator coil EXT, and the other half cycle output is short-circuited through the diode D2. In this circuit, thyristor S1
When the deterioration determination signal of is output from the AND gate AND, the thyristor S2 is turned on to prevent the capacitor C1 from being charged. When the thyristor S2 'is inserted in series with the charging coil as shown by the dotted line, the thyristor S2' is normally O.
N, the gate of the thyristor S2 'when a deterioration determination signal is generated
The circuit should be cut off.

The example in which the deterioration determining circuit of the thyristor of the present invention is applied to the ignition device has been described above. However, it is obvious that the invention can be applied to various devices using the thyristor, and an alarm display is made by using the deterioration signal. It can be used in various ways.

[0013]

As is apparent from the above description, according to the present invention, it is possible to judge the deterioration of a thyristor at an early stage with a simple structure. Therefore, the invention can be applied to various electronic and electric devices using the thyristor to protect the device. The effect is extremely large in terms of measures such as retention. (6)

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the present invention.

FIG. 3 Conventional example diagram

FIG. 4 is a diagram of an embodiment of the present invention.

FIG. 5 is an operation explanatory diagram of the present invention.

FIG. 6 is a diagram of another embodiment of the present invention.

[Explanation of symbols]

 S, S1, S2, S2 'Thyristor GC Gate circuit GK Gate-to-cathode voltage detection circuit IN Gate signal stop detection circuit AND logic circuit PW power supply D / D DC-DC converter EXT Power generation Coil C1 Capacitor SP Spark plug PC Pulser coil

Claims (4)

[Claims] 1. A power supply for supplying direct current (or alternating current) between the anode and cathode of a thyristor, a gate circuit for intermittently applying a gate signal to the thyristor, and the gate. A gate signal detection circuit for detecting a signal stop of the circuit,
A gate voltage detection circuit for detecting the gate-to-cathode voltage of the thyristor is provided, and the deterioration of the thyristor is judged by the logical output of the gate signal detection circuit and the gate voltage detection circuit. A thyristor deterioration determination circuit characterized in that 2. An igniter for an internal combustion engine, wherein a capacitor is charged by an output of a converter or a generator, and a charged load of the capacitor is discharged through a thyristor to an ignition coil. A circuit, a deterioration determining circuit for the thyristor, and a charge stopping circuit for the capacitor, and the charge stopping circuit for the capacitor is operated by an output signal of the deterioration determining circuit. . 3. A DC-D as a capacitor charge stop circuit.
3. The ignition device for an internal combustion engine according to claim 2, wherein an oscillation stopping means of a C converter is used. 4. The capacitor charging stop circuit comprises means for short-circuiting or opening the output of the generator by means of a semiconductor switch connected to the output side of the generator. An ignition device for an internal combustion engine as described above.