NOVELTY - The method involves providing two sub modules (22) in a series circuit, which draws electrical power from a power source i.e. battery, via an inductance. A battery voltage is outputted by the power source. Each sub module is provided with a single-phase half bridge (40) on an input side, and a single-phase full bridge (42) on a load side. A fault is detected in one of the sub modules. An electrical power transmission from output terminals (30, 32) of the full bridge of one of the sub modules with the detected fault into one of the sub modules with the detected fault is blocked.    USE - Method for protecting an intermediate circuit capacitor in a power converter circuit, which is used for supplying electrical power for windings of an electric motor i.e. asynchronous motor, of a vehicle (all claimed).    ADVANTAGE - The method prevents power flow at an output of the sub modules of the power converter circuit in case of fault, and avoids easily reversal of a main power flow direction in the individual sub modules of the power converter circuit. The method allows capacitance of the intermediate circuit capacitor to be dimensioned small, thus saving installation space and cost of the circuit. The method avoids high loading and destruction of the intermediate circuit capacitor, thus avoiding serious physical damages of the power converter circuit in case of fault. The method avoids uncontrolled supply of current from an electrical load into the full bridge, occurrence of short-circuit, and failure of the entire power converter circuit in case of failure of the defective sub module.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for the following:    (1) a control device    (2) a power converter circuit    (3) an electric motor.    DESCRIPTION OF DRAWING(S) - The drawing shows a circuit diagram of sub modules of a modular converter.    Sub modules (22)    Output terminals (30, 32)    Single-phase half bridge (40)    Single-phase full bridge (42)    Slave (62)