RU2605454C1 - Adaptive device for controlling power thyristor - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to electrical engineering and can be used to control power thyristors of rectifiers, independent inverters and thyristor contactors. Adaptive control device for power thyristor comprises power supply, current sensor, key device, threshold device, input of which is connected to output of current sensor, and its output is connected to control input of output voltage of power supply.

EFFECT: reduced power losses.

1 cl, 1 dwg

Description

The claimed technical solution relates to electrical engineering, namely to converter technology, and can be used to control power thyristors of rectifiers, autonomous inverters and thyristor contactors.

A device for controlling a thyristor is known, in which to limit the control current of the thyristor, an additional limiting resistance is connected in series with the control electrode [1]. Due to the scatter of the input current-voltage characteristics of the thyristors, the supply voltage of the thyristor control device should be quite large 10-15 V. Since the voltage on the thyristor control electrode is in the range 2-4 B, the power dissipated on the limiting resistor is 3-7 times exceeds the power dissipated on the thyristor control electrode.

Also known is a thyristor control device described in USSR author's certificate No. 576083 "Device for controlling a semiconductor valve" (class IPC H02M 1/08, priority date 11.26.1974) [2]. In this device, the thyristor control pulse is fed to the control electrode through a current stabilizer, which stabilizes the thyristor control current at a level that ensures the thyristor is turned on in all operating conditions, and allows you to approximately halve the amount of power consumption from the power source compared to the device [1 ]. In addition, this ensures minimum dissipation power at the thyristor control electrode.

The disadvantage of devices [1 and 2] can be considered that the power consumed from the power source is quite large.

Closest to the claimed technical solution and therefore adopted as a prototype is the "Device for controlling power thyristor" according to the USSR author's certificate No. 964894 (class IPC H02M 1/08, priority date 11.28.1981) [3].

This device contains a power source, a control current regulator of a power thyristor made on two transistors, and a thyristor control current sensor made on a resistor. One of the current stabilizer transistors is a key device, and the other is a threshold device. When a start pulse arrives, the current of the key device begins to flow, which is simultaneously the thyristor control current. As the control current rises, the voltage drop across the resistor of the current sensor increases. When the voltage across this resistor reaches the value at which the transistor of the threshold device opens, the collector current of this transistor will begin to decrease the base current of the key transistor. The output resistance of the key transistor will increase in this case, as a result of which the growth of the thyristor control current will stop and it will stabilize when the output voltage of the power source and the input current-voltage characteristic of the power thyristor change.

The disadvantages of this device include the fact that the voltage drop across the current stabilizing transistor does not allow to minimize the power consumed from the power source and the non-optimal thyristor control pulse shape, which should have a sharp short 5-10 μs current peak with amplitude, 5-10 times greater current holding the thyristor in the open state, to reduce the turn-on time of the thyristor.

The objective of the proposed technical solution is to obtain the lowest possible power consumption from the power source and the formation of the optimal pulse shape of the thyristor control current.

This problem is solved due to the fact that the transistor stabilizing the control current of the thyristor is eliminated, and the signal from the current sensor through a threshold device is fed to the control input of the output voltage of the power source.

The claimed technical solution is illustrated in FIG. 1, which shows a block diagram of an adaptive device for controlling a power thyristor that implements the minimum possible power consumption from a power source and the formation of an optimal pulse shape of the thyristor control current by adjusting the output voltage of the power source.

The inventive adaptive device for controlling a power thyristor contains a power source (1) with a thyristor (4) connected to it via a current sensor (2) and a key device (3). The output signal of the current sensor (2) is supplied to the input of the threshold device (5), the output of which is connected to the control input of the output voltage of the power source (1).

The inventive device operates as follows. When a start pulse is applied to the input of the key device (3), the key device (3) connects a power source (1) to the thyristor control input (4) through the current sensor (2). As a result of this, a large boost current of thyristor control (4) begins to flow. At the input of the current sensor (2), a signal appears above the threshold of the threshold device (5), as a result of which a signal is received at the control input of the output voltage of the power source (1), which reduces the voltage at the output of the power source (1). This voltage decreases until the thyristor control current (4) decreases to a value at which the signal at the output of the current sensor (2) does not equal the threshold of the threshold device (5). Moreover, the control current of the thyristor (4) ensures guaranteed maintenance of the thyristor (4) in the on state and does not depend on changes in the input current-voltage characteristics of the thyristor (4), for example, when the temperature of the thyristor (4) changes. Thus, the adaptive device for controlling the power thyristor provides a stabilized value of the thyristor control current (4) and the optimal shape of this current. The magnitude of the boosted thyristor control current (4) is determined by the value of the output voltage of the power source (1) before applying the pulse Uap, and its duration is determined by the value of the capacitance of the capacitor at the output of the power source (1) and the delay of the output signal of the threshold device (5).

The high cost-effectiveness of the adaptive thyristor control device is due to the fact that the output voltage of the power source (1) automatically adjusts to the input current-voltage characteristic of the thyristor (4) at a given value of the thyristor control current, while the minimum possible power is consumed from the power source (1). The inventive device is 1.5-2 times more economical than the known power thyristor control device [3].

If it is necessary to control two or more thyristors, for example, in three-phase thyristor contactors, the key device (3) is made in the form of a controlled pulse generator, and the thyristor control leads are connected to the key device (3) via transformers, and the primary windings of the transformers are connected in series.

The minimum power dissipated on the control electrode of modern power thyristors and ensuring the guaranteed inclusion of the thyristor in all operating conditions is 1-2 W. Modern switching power supplies with an output power of several watts have small overall dimensions. The current sensor (2) can be performed on a resistor, the threshold device (5) and the key device (3) on transistors. Therefore, the inventive device can be implemented in the overall dimensions of the charger for a cell phone.

Information sources

1. Abramovich M.I. and others. "Diodes and thyristors in converting devices." Moscow: Energoatomizdat, 1992, pp. 134-162.

2. USSR author's certificate No. 576083, cl. IPC H02M 1/08, priority date 11/20/1974

3. USSR copyright certificate No. 964894, cl. IPC H02M 1/08, priority date 01/28/1981

Claims (2)

1. An adaptive device for controlling a power thyristor, comprising a power source with thyristor control leads connected to it through a current sensor and a key device, a threshold device that is connected to a current sensor, characterized in that the output of the threshold device is connected to the control input of the output voltage of the power source . 2. The device according to claim 1, characterized in that when controlling several thyristors simultaneously, the key device is in the form of a controlled pulse generator, and the thyristor control leads are connected to the key device via transformers, and the primary windings of the transformers are connected in series.

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