Pwm frequency converter

Abstract

A multi-phase voltage-controlled PWM frequency converter, comprising at least one control unit (23), at least one rectifier bridge (20) designed to be connected to a multi-phase supply network (UU, UV, UW), a direct-voltage intermediate circuit and at least one controlled inverter bridge (21) for feeding at least one multi-phase load (22) with an alternating voltage (US, UR, UT) of varying magnitude and frequency. The inverter bridge has pulse width modulation-controlled semiconductor switches (V11-V16) and, in parallel with these, inverse-parallel connected diodes (D11-D16). The rectifier bridge has fully controllable semiconductor switches (V1-V6) and, in parallel with these, inverse-parallel connected diodes (D1-D6). The control unit controls the fully controllable semiconductor switches of the rectifier bridge in such manner that, in the upper arm, the switch of the phase concerned conducts substantially as long as the instantaneous value of the network phase voltage (UU, UV, UW) in question is the most positive, and in the lower arm the switch of the phase concerned conducts substantially as long as the instantaneous value of the network phase voltage (UU, UV, UW) in question is the most negative. The rectifier bridge (20) is connected to the inverter bridge (21) directly without a direct-voltage capacitor unit acting as an intermediate energy storage, and the direct current produced by the inverter bridge has been arranged to flow directly into the supply network without limitation of current peak value by an inductor unit.

Dependencies are inferred from the claim text.