Self-adjusting motor braking circuit

摘要

In the case of a control device for a thyristor (9) which is arranged in a braking circuit for DC braking of AC motor (11), it is intended that the braking current be set by means of the thyristor (9) automatically, via its phase-gating control. For this purpose, a current-detecting element (8) for detecting the arithmetic mean value of the braking current flowing through the AC motor (11) is provided in series with the thyristor (9). Connected downstream of the current-detecting element (8) is a form-factor stage (4) which multiplies the arithmetic mean value of the braking current by the form factor, as a function of the output signal of a voltage-detecting element (3) which detects the braking voltage. The output signal of the form-factor stage (4), which corresponds to the r.m.s. value of the braking current, is supplied as the actual value of the braking current to a regulator (6) which is connected on the output side to the triggering stage (1) of the thyristor (9). <IMAGE>