A drive system for a permanently excited synchronous machine includes a drive converter, and a control device, wherein terminals of the synchronous machine are connected to corresponding outputs of the drive converter by connecting lines. Controllable asymmetrically blocking semiconductor switches are arranged in each of the connecting lines, with each switch having a thyristor connected in parallel with a reverse-biased diode, with anodes of the thyristors and cathodes of the diodes connected together to corresponding terminals of the synchronous machine. A control device has an input receiving a fault signal and an output connected to control inputs of the drive converter. The control device further includes control outputs connected to control inputs of the semiconductor switches. An easily controlled protective circuit for the drive converter of the drive system is obtained.