A method for real-time testing of a control unit with a simulator is provided. The simulator calculates a load current and a load voltage as electrical load state variables via converter control data and via an electrical load model that does not take into account current discontinuities caused by the converter, and transmits at least a portion of the load state variables to the control unit. A control observer is additionally implemented on the simulator that calculates at least the load current as a load state variable taking into account the converter control data and an observer load model. The observer detects a zero-crossing of the load current and a current discontinuity caused thereby from the calculated load current, and upon detection of a current discontinuity the observer calculates an electrical compensating quantity.