CS232415B1 - Circuit for switching of semiconductor switching element - Google Patents

Abstract

The invention provides a circuit for switching semiconductor of the switching element by the expansion contact. The purpose of the invention is to realize a simple, cheap and reliable switching circuit of a semiconductor switching element expanding contact. The aeel of the ee reaches by being between a control electrode (7) and a semiconductor anode (8) a circuit is connected to the switching element (1) (3) control current phase rotation. The break contact (4) is connected between the control contacts a semiconductor switching electrode (7) the element (t) and the cathode (9) of the semiconductor switching device element (1). The circuit according to the invention is suitable everywhere tan, where switching of semiconductor switching is required an element by an expansive contact, e.g. in thermostats with a contact thermometer where presents a very simple rhythm with minimal consumption, negligible thermal power off and minimum radio frequency surge protection when switched on. Furthermore, in the case of alarm adjustments, thermal fuses etc.

Description

The invention solves a circuit for switching a semiconductor switching element by an NC contact. The essence of the invention is applicable in electrical applications in which we switch and disconnect the load without contact.

In the known circuits for switching the semiconductor switching element by an NC contact, in the simplest embodiment, a semiconductor switching element is connected in series with the control electrode connected via an anode limiting resistor and via the NC contact to the semiconductor switching element cathode. If the semiconductor switching element is to be switched at a voltage close to zero, the limiting resistance must be selected at least cn, taking into account the maximum permissible current and power dissipation of the control electrode of the semiconductor switching element used. Depending on the type of semiconductor switching element used, it is possible at best to switch on with a phase delay of 0.5 ° to 10 ° from the voltage passage of zero. Therefore, the circuit is not a negligible source of high frequency interference, especially when switching large currents. The power dissipation at the limiting resistor when the NC contact is closed is considerable. The maximum breaking current is 1 to 2 orders of magnitude greater than the rated control current of the semiconductor switching element. Known circuits with better properties are considerably more complex and therefore more expensive.

The above-mentioned drawbacks are eliminated by the circuit for switching the semiconductor switching element according to the invention. The principle of the invention is that a phase rotation circuit of the control current is connected between the control electrode and the anode of the semiconductor switching element.

Due to the phase rotation of the control current, the semiconductor switching element is switched with a minimum phase delay from the voltage passage to zero, practically when the switching voltage reaches the switch-on voltage value of the semiconductor switching element used. Therefore, the circuit according to the invention is characterized by a very low level of radio interference. Since the control current is phased against the voltage by almost 90 °, the effective power dissipation with the NC contact closed is considerably lower than that of the previously known single circuits.

The circuit has a minimum number of components and therefore the dimensions and weight of the realized wiring are small.

In the accompanying drawing, an example of a circuit for switching a semiconductor switching element is a break contact.

A control current phase reversal circuit J is connected to the control electrode I of the semiconductor switching element 11 (thyristor, thrust, etc.) by a first connection point 10, and a current reversing circuit 2 is connected to the anode 8 of the semiconductor switching element. J ..

The function of the circuit according to the invention is as follows: when the break contact is closed, the control electrode of the semiconductor switching element J is connected to its cathode. The semiconductor switching element J is closed. Upon opening of the NC contact 1, the control electrode of the semiconductor switching element J is supplied with a phase-shifted current of almost 90 ° against the voltage.

This makes it possible to switch on the semiconductor switching element practically at zero voltage.

The circuit according to the invention is suitable wherever the semiconductor switching element needs to be switched by an NC contact, for example in thermostats with a contact thermometer, where it is a very simple solution with minimal consumption and thus low thermal output in the off state. Furthermore, alarm systems, thermal fuses, etc.

Claims (1)

OBJECT OF THE INVENTION Circuit for switching the semiconductor switching element by an NC contact comprising a semiconductor switching element, an NC contact and a load, characterized in that a phase (3) of the phase rotation of the control circuit (3) is connected to the control electrode (17) of the semiconductor switching element (1). The control current phase rotation circuit (3) is connected by a second connection point (11) to the anode (8) of the semiconductor switching element (J).