Control device and method for determining the rotor angle of a synchronous machine

A method for determining the rotor angle of a synchronous machine, the method comprising:

• generating a multiplicity of pulse-width-modulated drive signals for the phases of an inverter feeding the synchronous machine depending on a voltage to be fed into the synchronous machine;
• applying a first phase shift to one or more of the multiplicity of pulse-width-modulated drive signals, with the result that the duration of the switching states of the inverter in which an active voltage phasor is output is extended in order to generate a first switching pattern for the phases of the inverter;
• applying a second phase shift to one or more of the multiplicity of pulse-width-modulated drive signals for generating a second switching pattern for the phases of the inverter;
• selecting one or more of the first and second switching patterns for driving the inverter;
• determining one or more of neutral point potentials at the neutral point of the synchronous machine during driving of the inverter with the selected switching patterns;
• and
• calculating the rotor angle of the synchronous machine depending on the determined neutral point potentials.