Abstract: A signal converter for a motor drive of an electric motor comprises an operational amplifier, having an inverting input, a noninverting input and an output, and an integrator, the output signal of which being provided as a reference signal to the inverting input of the operational amplifier. An actual signal level corresponding to a measured voltage level as well as an auxiliary signal are provided to the noninverting input of the operational amplifier. The integrator is connected to a first summing point. The first summing point is connected by way of a first lowpass filter to the output of the operational amplifier and by way of a second lowpass filter to the noninverting input of the operational amplifier. The noninverting input of the operational amplifier is also coupled by way of a second summing point to the actual signal input and to an amplifier circuit. A reference signal is provided to a first input of the amplifier.

Abstract: An improved signal converter which isolates a measurement voltage by converting an analog signal into a pulse-width-modulated output signal. The converter has a first integrator followed in series by a threshold value controller whose output signal actuates at least one reversing switch element which supplies to the summing point of the first integrator at which the signal prevails, and to the threshold value controller, either a positive or negative reference voltage. This signal converter has a very low offset and a high linearity at high sampling rates. The signal also has a second integrator whose summing point is also connected to the signal input and output of the reversing switch element. The output signal of the second integrator is the reference signal of the first integrator. The linearity of the signal converter is thus exclusively dependent upon the parameters of the second integrator.

Abstract: A triangle waveform generator having a comparator which drives an integrator via a limiter is disclosed. At the output of the integrator, the desired triangular waveform voltage is present. The output of the integrator is connected to a first input of the comparator. The output of the comparator is fed back to its first input via a resistor. The output of the integrator is coupled via an integral action controller to a second input of the comparator. The integral action controller has a substantially longer time constant than the integrator. With this circuit, a triangular voltage is obtained, the parameters of which, namely, the slope and the positive and negative peak values, depend only on resistors and reference voltages which can be set within narrow tolerances.

Abstract: Method and circuitry for generating drive pulses for a DC control element of the type having four semiconductor switches arranged in a bridge circuit. Two triangular voltage waveforms are formed and are shifted with respect to one another by a difference voltage. Each bridge branch of the bridge circuit is driven in response to a comparison between the first triangular voltage waveform and a control voltage, and a second semiconductor switch of each bridge branch is driven in response to a comparison of the second triangular voltage waveform and the same control voltage. A pause between the conductive periods of the semiconductor switches within a bridge branch is obtained by driving the semiconductor switches with offset triangular voltage waveforms. The pauses prevent short circuits of a supply voltage source, and their duration is determined by the difference voltage and can therefore be achieved accurately at low cost.