Method and circuit for detecting an open line of the sine/cosine receiver coil of a resolver

Circuit for detecting an open line of a receiver coil of a resolver, the circuit comprising:

• a control device with a processor, power stages, first terminals for providing signals at the exciter lines to the exciter coil of the resolver and second terminals for connecting the signal lines for the signals of the sinusoidal and the cosinusoidal coil;
• two AD converters which are connected to the second terminals of the control device and the outputs of which can be read and evaluated by the processor;
• the exciter lines which couple the first terminals to the exciter coil of the resolver;
• the signal lines to be diagnosed for the sinusoidal and cosinusoidal signals provided by the resolver, which couple the resolver to the second terminals of the control device;
• pull-up resistors which are connected with their one end to one of the terminals for the lines of the sinusoidal coil and the cosinusoidal coil and with their other end to a first direct-voltage potential;
• and
• pull-down resistors which are connected with their one end to the other one of terminals for the lines of the sinusoidal coil and the cosinusoidal coil and with their other end to a second direct-voltage potential, the second direct-voltage potential being lower than the first direct-voltage potential, in such a manner that the voltage difference lies between and in the measuring range of the AD converters;
• and a display or storage device for displaying or storing the information identified by the processor, into which the positive detection of an open line of one of the receiver coils of a resolver is included.