DE2154454A1 - CIRCUIT ARRANGEMENT FOR THE SPEED CONTROL OF ELECTRIC MOTORS - Google Patents

Description

STANDARD ELEKTRIK LORENZ AG £ Ib 4% 0 ¹ ^

Stuttgart

Case: B.Walter-D.H.Walther 4-3

Circuit arrangement for speed control of electric motors

The invention relates to a circuit arrangement for controlling the speed of collector series motors for AC operation, so-called universal motors, by influencing the ignition timing of a controllable Semiconductor device connected in series with the motor on the AC mains.

It is already known that the speed of electric motors in in such a way that a controllable semiconductor device is placed in series with the engine, the ignition timing of which is shifted with respect to the AC mains voltage. When the motor is fed from the AC network usually a bidirectional conductive semiconductor element used, for example under the name "Triac" is known in the art. By shifting the starting point of this semiconductor element within a half period With the AC mains voltage, it is possible to control the motor current and thus the motor power .

The controllable semiconductor device is usually by discharging a capacitor via a contactless electrical Switching element, such as a trigger diode, ignited. Here is a shift of the ignition point in the

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B.Walter-D.II.Walther M - 3

In this way it is possible to influence the charging of the ignition capacitor. Such a change in the charging time of the Ignition capacitor can also depend on the speed of the Motor or its residual EMF are made automatically, so that it is then an automatic control of the Motors acts.

It is already known in such circuit arrangements for controlling or regulating electric motors by a The electrical voltage proportional to the speed creates a negative feedback on the charging current of the ignition capacitor to exercise a half-wave of the mains AC voltage, so that part of the charging current of the ignition capacitor is parallel to this is derived. This known circuit arrangement does indeed result in an increase in the set idling speed prevented, but it has the disadvantage that the charging of the ignition capacitor does not have the by the Adjustment resistor predetermined target value can be increased, so that it is not possible to achieve the maximum To achieve switching time of the controlled half-wave.

To the circuit arrangement mentioned, which has a charging current diverter caused during a half-wave, it is also known in the case of the braking of the motor Current increase a cancellation of the charging current derivation to achieve.

Furthermore, circuit arrangements are known in which during a half-wave the charging of the ignition capacitor is influenced by the flow of current through the motor to "at the subsequent half-wave of the same polarity a faster one To achieve the ignition voltage.

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There are also known circuit arrangements in which the charging speed of the ignition capacitor in both Half-waves of the heating voltage is preselected by a setting resistor, but the automatic leveling only during a half-wave takes place, i.e. only one direction of charge of the ignition capacitor is influenced by the control can be. These circuit arrangements have the disadvantage that when the motor is loaded, despite the level effect, the full torque, which the motor is able to deliver, is achieved. This is due to the fact that the unregulated Half-wave, especially when the motor is running at a set low speed, do not reach the full angle of current flow can, so that the full engine power is never achieved.

The task of the P.rfindung is to provide a circuit arrangement for Speed control by influencing the charging route of a To create ignition capacitor in which the ignition angle can be shifted in a very wide range, so that a very favorable torque-speed counting curve is achieved especially at low engine speeds.

This task is accomplished by a circuit arrangement for speed control a series collector motor fed from the alternating current network via a bidirectionally conductive semiconductor device, at which the ignition timing of the bidirectional conductive semiconductor device from the charge a capacitor is determined, which via a trigger diode with the control electrode of the bidirectional conductive Semiconductor device is connected, according to the invention achieved in that the charging current of the capacitor at one half-cycle of the voltage induced by the motor is affected.

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B.Walter-D.R.Walther 4-3

According to the further development of the invention, this is thereby achieved achieved that in the charging circuit of the ignition capacitor in series with a variable resistance of the base-collector circuit of a transistor is that a diode is anti-parallel to the base-collector circuit of the transistor, and that the base-emitter circuit of the transistor is in series with the variable resistance at the terminals of the motor.

A field effect transistor is preferably used as the transistor used.

The invention is to be explained in more detail with reference to the drawing will.

Figure 1 shows the circuit arrangement according to the invention. FIG. 2 shows the waveform at the motor terminals.

The collector series motor M is in series with the controllable semiconductor device Tl on the AC network. It concerns the controllable semiconductor device T1 Preferably a triac is used for a bidirectionally conductive semiconductor device. The ignition point of the controllable Semiconductor device Tl depends on the charging of the capacitor Cl, which via the trigger diode Dl with the Control electrode of the controllable semiconductor device Tl is connected. According to the invention, the charging current is of the ignition capacitor Cl in a half-cycle by the high-voltage transistor T2. influenced, while the Aufladestron of the ignition capacitor Cl flows through the diode D3 in the other half-cycle. The charging current can be changed by the variable Resistance Rl can be adjusted. The charging current for the capacitor therefore flows in one half-cycle Cl via the variable resistor Rl and the resistor R2 via the base-collector circuit of the transistor T2.

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The base-emitter circuit of the transistor T2 is also connected to the clamps via the resistor R4 and the diode D2. of the motor M connected so that it is influenced by the voltage induced by the motor.

ι The voltage curve at the terminals of the motor M is in Figure 2 shown schematically.

The ignition time of the controllable semiconductor device Tl is at the angle qC with respect to the beginning of the half-wave shifted, so that? "So each half-wave only partially" has an effect.

As a result of the voltage induced by the motor M, a voltage peak A occurs at the beginning of each half-wave, which can be observed on the oscillogram. This voltage spike A is caused by the motor inductance, which after erasing the controllable semiconductor device continues to maintain the motor current until the magnetic field collapses. The voltage peak A is used according to the invention to influence the charging of the capacitor Cl via the transistor T2 and therefore determines the ignition angle JC . If the motor is braked by an external load, the induced voltage peak A increases, so that the transistor T2 continues to be turned on. The charging of the capacitor Cl is accelerated and the ignition angle oC is brought forward. In this way, more energy is supplied to the motor and the original speed is reached again.

Due to the variable resistance Rl, the through the Transistor T2 can be influenced flowing current, whereby

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an adjustment of the per.el gain to the respectively set Ignition timing is possible. Preferential rates will be available as Transistor T2 uses a field effect transistor.

L -.- i of the circuit arrangement according to the Irfin ^ and the Aufladestron: of the ignition capacitor Ci in an i-ali -wellc from zero to :: u a value controlled by the Crenzrclantun "les Fochspannungstransistor T2 ΐ« grounded As a result, supported by the operating point presetting by means of the variable resistance Ti , the? Iinclk angle can vary under the influence of the control unbeinalic I "0 '. Through this Fute 'cc'; re * Glu: r, ir.übesondere reached on Low ^T I otordrehzahl, a very favorable course of ^ rehrouient-speed curves.

Attachments:

3 claims
1 sheet of drawings
1 List of Reference Numbers

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Claims (3)

E. v.'alter-D. II. Ualther H - 3 claims 1.) j Circuit arrangement for speed control of one of the AC power system via a bidirectional conductive semiconductor device powered series connection collector motor, at which the ignition timing of the bidirectional conductive semiconductor device is determined by the charging of a capacitor, which via a trigger · ^ iod e nit the control electrode the bidirectional conductive semiconductor device, is connected, characterized that the charging current of the capacitor (Cl) with a half cell of the voir. Motor GO induced voltage is affected. 2.) Circuit arrangement according to claim 1, characterized gekennzeichnct that iir charging circuit of the capacitor (Cl) in series with a variable resistor (Rl) of the base-Kollcktor circuit of a transistor (T2) is that a diode (D3) anti-parallel to Base-collector circuit of the transistor (T2) is, and that the base-emitter circuit of the transistor (T ?.) is in series with the variable resistor (Rl) at the terminals of the motor (M). 3.) Circuit arrangement according to claim 1 or 2, characterized in that the transistor (T2) is a field effect transistor if.t. IV / L - 11 10.1971 309818/0622
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