Abstract: A method is for the pulse width modified control of switching elements in a frequency converter having N phases, in which for each phase the control pulses of the switching elements are derived from, in each case, one P-periodic control voltage. The P-periodic control voltages correspond to a superposition of sinusoidal control voltages of period P, that are shifted by 360/N degrees with respect to one another, by an N*P-periodic offset voltage that applies to all phases. The offset voltage is selected such that, at any time, exactly one of the P-periodic control voltages lies effectively on a modulating limit for the derivation of the switching pulses. Using this method, the excitation of resonances at the star point of a connected load may be clearly reduced.

Abstract: A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools. The control structure includes an rpm regulator having a proportional component and an integral component. The control structure further includes an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components, and a summing point that is upstream or downstream of the integral component and receives the low-frequency correction signal.

Abstract: A control structure for the active damping of low-frequency oscillations in numerically-controlled machine tools. The control structure includes an rpm regulator having a proportional component and an integral component. The control structure further includes an active damping element that forms a low-frequency correction signal, which is phase-shifted with respect to an interfering low-frequency oscillation and free of d.c. components, and a summing point that is upstream or downstream of the integral component and receives the low-frequency correction signal.

Abstract: In a position measuring apparatus there is provided a subdivision circuit for the subdividing of sinusoidal scanning signals. The subdivision circuit includes rectifier circuits in which the scanning signals are reformed in such a way that over a total signal period one rectified signal always has a greater signal value than the other rectified signal. The rectified signal with the greater signal value lies on one reference input and the other rectified signal lies on the other reference input of an analog-to-digital converter. The analog-to-digital converter forms from these rectified signals a binary word which is fed to a correction arrangement. Together with code signals which define four equal sections of a single period, the correction arrangement generates a data word which represents intermediate values of a signal period of the scanning signals.