Control device for a reversible converter without any loop current

摘要

In this control device for a reversible converter which is supplied from a three-phase network, in a reverse-parallel connection of two three-phase bridges, a current direction transmitter (14) without any switching hysteresis is used to initiate reversal of the current direction. The current direction transmitter (14) causes an alternating reversal in the current direction at triple the network frequency in the case of small currents, in order to keep the current controller (3) always ready to react and in order to prevent disturbing dead times and unacceptable current surges during a reversal in the current direction. In order to generate the changeovers at triple the network frequency, the triggering pulses (Z) of the triggering equipment (16) are collected by means of a pulse collector (20) and are supplied to a frequency divider (22) via a pulse extender (21). The frequency divider (22) controls a polarity reverser (11) to which the desired current value (Ides) is applied and whose AC voltage on the output side is added to the desired current value (Ides) and supplied to the current direction transmitter (14). The control device can be used in drive technology for supplying DC motors. <IMAGE>