Abstract: A digital current regulator circuit for a DC load that is connected within a transistor bridge circuit for multi-quadrant operation contains a digital comparator to which binary actual value codes and theoretical value codes are applied as well as a control unit for the time-discrete unipolar control of the transistors in dependence on a central timing signal. To avoid current distortions when the polarity of the load current changes, a blocking circuit is provided, by means of which the bridge circuit can be blocked when the polarity of the theoretical value code changes. A release circuit is also provided that terminates the blockage as soon as the load current actually becomes zero.

Abstract: A digital current regulator circuit, especially useful for a DC motor, is described which is fed directly, i.e., without power transformers, from the AC mains, via power transistors (T1-T4) that are controlled by pulse modulation and which can work in four-quadrant operation. An A/D converter (12) generates from samples of the motor current, an actual-value signal in the form of a multi-bit parallel binary code; and a binary comparator (20) compares the actual-value code with a theoretical-value code and generates binary error signals if the actual value is greater or less than the theoretical value. To provide DC-isolation of the power transistors and associated circuitry from the control circuitry that generates the error signals, the parallel bits of the actual-value code are transmitted to the control circuitry through an opto-electronic coupler (14). Other opto-electronic couplers (16, 30) can be provided to transmit other control signals.

Abstract: A transistor control unit for a servo motor has its control part and its power part arranged on a single printed circuit element. The control part and a cooling body, power transistors and power diodes of the power part are located side-by-side on one side of the element, the current connections being on the other side. Resistance arrays in flat rectangular housings are mounted end-on on the element with their main surfaces vertical when the element is mounted in position.