DD288697A5 - ELECTRONIC CONTROL UNIT FOR MAINS VOLTAGE-OPERATED HALF-WAVE CONTROL SYSTEMS - Google Patents

Abstract

The invention relates to an electronic drive circuit for mains voltage-driven half-wave drive systems, in particular for miniature relays, wherein a changing input magnitudes converted by means of a sensor in a veraenderliche voltage and an evaluation circuit is supplied and wherein the output of the evaluation circuit for driving an electronic switch with downstream Halbwellentriebsystem. According to the invention, the unswept half-wave of the mains alternating voltage is applied to the half-wave drive system and the electronic switch is connected in parallel to the half-wave drive system. Fig. 1 {drive circuit; Half-wave drive system; Miniature relays; unswept half-wave; Mains voltage; electronic switch; sensors; evaluation}

Description

Field of application of the invention

The invention is the electronic control for mains voltage operated half-wave drive systems, such as relays, contactors and similar actuation and tripping devices that are connected directly to the mains voltage.

Characteristic of the known state of the art

From DE-OS 27 57 563 a drive circuit for a triac is known, wherein a transistor is connected in series with the triac. The disadvantage here is the required high blocking voltage in the range of the mains voltage for dt η transistor to ensure the function of the circuit. Furthermore, it is disadvantageous that the series resistor for the power supply of the triac has a power consumption of 2 to 3 watts, which leads to high operating costs for devices and consumer goods with a long service life.

From DE-OS 3118416 a drive circuit for an electromechanical relay is known, wherein a thyristor or a transistor is connected in series with the relay. The disadvantage here is also the required high reverse voltage for the transistor. A further disadvantage is that to hold the relay during the negative half-cycle of the mains AC voltage a relay connected in parallel capacitor is required, which must be very voltage resistant to high voltage spikes AC mains voltage and requires the largest possible capacity to avoid chattering of the relay. This circuit cost leads to a high power consumption of the Gessmtschaltung. From DE-OS 2547 514 a circuit for a twilight switch is known in which a capacitive voltage divider with subsequent rectification is used to power the relay. A disadvantage of this arrangement is that the filter capacitor requires a large capacitance for the best possible rectification and, because of large tolerances of the capacitor connected in front of the rectifier bridge, problems arise in adapting the relay to the necessary operating voltage and temperature ranges. These problems can be solved only with additional effort to stabilize the operating voltage.

Object of the invention

The aim of the invention is to provide an electronic drive circuit for mains voltage-driven half-wave drive systems, wherein the power consumption of the overall circuit is substantially reduced.

Explanation of the essence of the invention

The object of the invention is an electronic drive circuit for mains voltage operated half-wave drive systems, in particular for miniature relays, wherein a changing Eingangsgiöße converted by a sensor into a variable voltage and an evaluation circuit is supplied, the output signal for driving an electronic switch, and the electronic switch Semi-wave drive system is arranged to create.

It is a further object of the invention that the power consumption of the drive circuit is reduced by reducing the circuit complexity of power consuming devices and the electronic switch requires no high reverse voltage in the range of the mains voltage.

According to the unswitched half-wave of the mains alternating voltage is applied to the Halbwellentriubsystem, which has been known to be generated via a series connection of a resistor and a diode. It is arranged according to the invention, the electronic switch parallel to the half-wave drive system.

In the first switching state, i.e. as long as there is no output signal from the evaluation circuit at the electronic switch, the electronic switch is open so that no current can flow through it and the current flows completely through the half-wave tri-system. Thus, the half-wave drive system switches to the first switching state, which it maintains as long as the electronic switch is open.

As soon as a signal is present at the output of the evaluation sound due to the changing input variable, the electronic switch switches through, ie. H. it is closed, and the current flows almost completely through the electronic switch, therefore, the half-wave drive system switches to the second switching state, which it maintains as long as the electronic switch is closed.

embodiment The invention will be explained in more detail with reference to the following embodiment.

1 shows a drive circuit for a half-time alternating current relay, which switches on and off a lighting system as a function of the daytime brightness.

As a sensor for detecting the variable daytime brightness as an input variable is a phototransistor V1. The stabilized Operating voltage for serving as evaluation comparator V2 is known from the AC line voltage Won way and manner. The collector of the phototransistor is provided with a resistor R1 and the noninverting input

connected to the comparator V2, wherein over the series circuit of resistor R1 and phototransistor V1, the stabilized

Operating voltage is. The resistor R1 forms with the phototransistor V1 a light intensity-dependent voltage divider. The inverting input

of the comparator V2 is applied via a voltage divider with a defined voltage, here half the operating voltage. As an electronic switch is a transistor V3, whose base via a resistor to the output of

Comparator V 2 is connected. According to the unswept half-wave of the AC line voltage, which is known via a series circuit

a diode D1 and a resistor R 2 has been generated, provided for the operation of the associated relay RS with normally closed switch contact.

The function of the drive circuit will be described below with decreasing and increasing daylight

become.

If the daylight brightness decreases, the resistance of the phototransistor V1 increases and the potential at the noninverting input increases

the comparator V2 also. As soon as this potential reaches the potential value at the invei ting input, the

Comparator V2 an output signal and the transistor V3 becomes conductive. By means of a between non-inverting input

and output of the comparator V2 switched resistor R3 a Schalthysierose is realized, which is a safe

Turning of the transistor V3 allows. Thus, the current flows through the collector-emitter Svrecke of the transistor V3 and the

Relay RS connected in parallel drops out so that the lighting system is switched on.

On the other hand, if the daylight increases, the phototransistor V1 becomes conductive and the comparator V2 no longer gives an output signal

as soon as the potential at the non-inverting input of the comparator V2 is smaller than the potential at the inverting

Input of the comparator V2 becomes. Then no current flows through the transistor V3 and the relay RS attracts, since now the

unswitched half-wave of the mains AC voltage is applied to the relay RS, and the lighting system is switched off.

A freewheeling diode D2 in parallel with the relay RS limits possible voltage peaks when the relay RS drops to protect the relay Transistor V3. Since no sieved half-wave is required to operate the relay RS, eliminating the expense of an additional capacitor

Parallel to the relay and the resistor RS can be significantly higher impedance, so that the power loss over R 2 is substantially reduced.

Due to the parallel arrangement of transistor V3 and relay RS, the transistor V3 requires a lower by about two-thirds Reverse voltage as in a series connection to the relay RS.

Claims (1)

Electronic control circuit for mains voltage driven half-wave drive systems, in particular for miniature relay, wherein a changing input variable converted by a sensor into a variable voltage and an evaluation circuit is supplied, the output of the evaluation circuit for controlling an electronic switch, which is followed by the half-wave drive system, and one with the Mains voltage connected series circuit of a resistor and a diode is connected to the half-wave drive system, characterized in that the unswept half-wave of the mains AC voltage and the electronic switch is angeodnet parallel to Halbwellentriebsystem the half-wave drive system. For this 1 page drawing