Circuit and method for multiphase operation of an electrical machine

A circuit for operating an electrical machine, the circuit comprising:

• a frequency converter for connecting to at least three phases of a power supply network, said frequency converter having a DC intermediate circuit;
• a direct current (DC) chopper controller;
• and
• a synchronous inverter, energy generated by the electrical machine being fed back into the power supply network by means of said synchronous inverter being driven by said DC chopper controller, said synchronous inverter having two bridge halves for switching positive and negative half-waves respectively, said synchronous inverter being of an asymmetrical configuration such that, for switching a potential being tapped off from said DC intermediate circuit by said DC chopper controller, switching is performed by a first bridge half having thyristors as electronic switches, and a second bridge half having reverse-blocking electronic switches which can be switched off.