Circuit arrangement for supplying an AC motor or three-phase motor via a pulse-controlled invertor (pulse-width-modulated invertor)

摘要

The subject-matter of the application is a circuit arrangement for supplying an AC motor or three-phase motor via a pulse-controlled invertor having electronic switches and freewheeling diodes connected in reverse parallel therewith, and having a capacitive DC voltage intermediate circuit having constant, or virtually constant, voltage, the current fed back from the motor inductance to the capacitance of the DC voltage intermediate circuit being detected and a signal being formed from it for regulating the reactive current of the motor. It is now intended to develop such a circuit arrangement in order that, in this case, the feedback current can be measured sufficiently accurately, as the reactive-current component of the intermediate circuit current, at the externally located connecting terminals of the pulse-controlled invertor. For this purpose, auxiliary diodes are arranged between the invertor outputs on the motor side and one of the poles of the intermediate circuit, and at least one of the DC voltage power connections of the invertor is connected via a series diode to the DC voltage intermediate circuit, the current flowing through the auxiliary diodes being measured as the feedback current. IMAGE