DE1588380A1 - Arrangement for pulse control of DC motors - Google Patents

Description

Dr. HEINZ FEDER files 67-10-107 ^{Ί b ö ö J ö u}

Patent attorney "

4 Düsseldorf ^{12 October 1967}

An vVehrhahn 77 / Ir.

ffcompany Theodor Kiepe, electrical engineering factory, Düsseldorf-Reisholz

Arrangement for «pulse control of DC motors

The invention relates to improving the pulse control of direct current motors, in particular from a battery powered series motors for small vehicles, in which the motor diodes are connected in parallel, in the direction block the direct current, there are control systems for direct

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Electric motors known, in which a with a controlled semiconductor element, for example in the form of a thyristor and equipped with a capacitor % , between a battery as a direct current source and the electric motor to be controlled arranged pulse generator circuit breaks the direct current into individual pulses, with a device for regulating the pulse frequency and the average engine power is provided. It is also known to connect an uncontrolled valve in parallel to the motor in such a control system to maintain the flow of current in the motor during the pulse pauses in such a way that it blocks in the direction of the direct current, on the other hand for the one flowing through the valve in the opposite direction, due to the inductance of the Field winding generated when switching off the current is permeable. For this purpose, a diode is usually used, which is referred to as a freewheeling diode. It is also known to provide a second diode in addition to this free-wheeling diode, which is only connected in parallel to the armature of the motor and, like the free-wheeling diode, blocks in the direction of the direct current, on the other hand for the end_d§r_Im; Qulsßau £ ie, n

break / Em anchor generated bromine permeable i3t. These anchor currents So they do not flow through the field winding, but can compensate each other directly through this second diode, which acts as an armature brake diode referred to as,

The pulse control in such devices includes one Thyristor or several thyristors, which have an ignition and a

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Extinguishing device is assigned. Usually one of these thyristors is used to cancel the pulses. After turning on of the thyristor (s), the direct current rises and sounds when the current is switched off via the freewheeling diode again after an exponential function.

It is also known to use direct current hot-wound motors Polarity reversal of the armature or field winding while maintaining the one used for the motor drive. Circuit through To slow down counter-current braking, for which a reverser or individual changeover contactors are required. As an introduction With the countercurrent braking, the motor current is first reduced to Hull with the usual pulse control devices, then the polarity of the motor armature or the excitation field winding is reversed and the motor current is then increased again. This current generates a power flow and thus an electromotive force Force in the motor armature that generates a current through the freewheeling diode during the currentless pulse pauses of the thyristor can flow into the excitation field winding. The electromotive force in the motor armature and thus the Motor braking current increases so quickly as a result of self-excitation that the vehicle, as a result of the sudden increase in braking current is brought to a halt almost instantly. In addition, the contactors are switched if necessary under full power, so that the contactor contacts are heavily used. This is undesirable for various reasons ^ and is viewed as disadvantageous, and therefore also

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_ ₄ _ 158838Ό

a risk to the vehicle driver can be associated.

The invention has set itself the task of a pulse control of the type described, which occur when switching back ^ - or switching the motor to counter-current braking Eliminate disadvantages. Rather, it should be achieved that the small vehicle in a stable manner, i.e. without the occurrence a jerky sudden delay, quickly brought to a halt it can be that it can start up again in the normal way in the opposite direction and that the contactors are switched takes place without performance.

This is achieved according to the invention in that two changeover contactors are arranged between the terminals of the field winding and the connections of the freewheeling diode and the braking diode on the one hand and the armature winding and the battery on the other hand, that with the position of the contactors, one diode always changes as Armature braking diode parallel to the motor armature, the other diode as a freewheeling diode parallel to the series connection of the motor armature-field winding . The invention therefore requires the use of an armature braking diode and a / freewheeling diode, and these diodes exchange their functions when switching over .

In order to ensure that the contactors switch without power in such an arrangement, the actuation of the contactors can also be used be designed so that when switching the two contactors are operated one after the other in solo sequence that in the

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In the meantime between actuations "both diodes in parallel to the motor anchor. A further improvement can be achieved in that a control device is provided which "with countercurrent braking to limit the duty cycle the pulse generator can serve. This control device can either be controlled by the voltage drop across the motor armature diode connected in parallel, or by the voltage drop across a measuring resistor in the motor circuit to be influenced.

This tension can optionally be carried out via a sieve element Amplifier in the pulse generator the duty cycle and thus the mean value fed to the excitation field winding of the motor Energy or voltage to an assignable, from the voltage conductor ratio of the lock voltage of the motor armature diode limit dependent value.

In the drawing , an embodiment of an arrangement for pulse control of DC motors according to the invention is shown.

The series motor with the motor armature A-B and the - ^ exciter field winding E-P is fed from the direct current source Gl. To break down the direct current into individual pulses, a thyristor Th is switched on in the circuit, which is connected to the Amplifier V is controlled.

The resistors Rl, R2 form together with the diode D3 and the capacitor C is the filter element of the pulse generator.

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Between the two resistors R1 and R2, the base of a transistor Tr is connected, the collector of which the amplifier V drives.

The output of this amplifier is connected to the control electrode of the thyristor Th. The amplifier is controlled by a potentiometer 5 influences, which is operated by the accelerator pedal and is used to regulate the pulse frequency.

The exciter field winding E-F_ is on the one hand with the motor armature A-B and with the thyristor on the other hand through the two contactors 1 and 2 in connection. To the two terminals of the excitation field winding are also the diodes Dl and D2 connected, which are connected so that they block the direct current supplied by the vehicle battery.

The direct current supplied by the vehicle battery Gl flows through the armature A-B always in the same direction, on the other hand the field winding E-F depending on the position of the contactors 1, 2 in opposite directions.

Assuming the extended, drawn position of the contactors 1 and 2, the result is: the current supplied by the battery flows through the motor armature in the direction AB and through the excitation winding in the direction EF; The circuit is closed via the thyristor Th , the diodes Dl and D2 block. During the pulse pause of the thyristor Th, the energy stored in the field winding continues to flow through the diode D2 and the motor armature.

009884/0 * 337

If there is now to be a transition to counter-current braking, then first brought the contactor 2 into the position shown in dashed lines. This circuit takes place without power, because it is through the contactor 2 no current is interrupted.

Then the contactor 1 is brought into the position shown in dashed lines. This switching is also done without power, because the previously flowing through the contactor 1 and the diode Dl

Current now also flow through the contactor and the diode D2.

The current supplied by the battery now flows through the field winding in the direction of PE, ie the direction is reversed as intended, the motor is driven to the opposite direction of rotation.
The armature circuit is not interrupted at all.

When the pulsation starts again, the motor armature now generates an electromotive force, which is positive at connection point B and that of the two diodes Dl and D2, which, depending on the switch position of the contactors, is parallel to the armature, drives a current within the armature circuit. Through this the motor is braked to a standstill and can then start up again as usual in the opposite direction of rotation will.

In the circuit shown in the drawing, the filter element D3, -Rl, -R2, -G is connected to the forward voltage of the respective

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to the motorani: he diode Dl or D2 connected in parallel. Instead, a measuring resistor can also be used in the motor circuit are switched on, and the filter element can then be connected to the terminals of this measuring resistor, the voltage of which is the respective Armature voltage is proportional to be connected.

Claims

009884/0337

Claims (3)

Patents (1st / arrangement for pulse control of direct current motors, in particular series-wound motors for small vehicles fed by a battery, "in which a motor armature and field winding bridging diode (freewheeling diode) and a second diode bridging the motor armature (armature braking diode) are provided, both of which are in the direction of the Block direct current, characterized in that two changeover contactors (1, 2) are arranged between the terminals of the field winding (EF) and the connections of the diodes (Dl, D2) on the one hand and the armature winding (AB) and the battery (Gl) on the other hand, that, changing with the position of the contactors, one diode in parallel with the series connection of the motor armature and field winding is always used as a freewheeling diode and the other diode in parallel with the motor armature as the armature braking diode. 2. Arrangement according to claim 1, characterized in that when switching the two contactors are operated one after the other in such a sequence that in the meantime between the operations, both diodes are parallel to the motor armature. 3. Arrangement according to claim 1 or 2, characterized in that in the case of countercurrent braking, the voltage drop across the diode (armature brake diode) connected in parallel to the motor armature serves to limit the pulse duty factor of the pulse generator. 4; Arrangement according to claim 1 or 2, characterized in that with countercurrent braking the voltage drop in one, in the motor - 2 -009884/0337 Measuring resistor located in the circuit to limit the duty cycle .The pulse generator is used. 009884/0337