Method for detecting an insulation fault in a motor arrangement, method for detecting a motor phase interruption in a motor arrangement, and drive circuit for driving an electronically commutated motor

A method for detecting a motor phase interruption in a motor configuration, motor phases of motor configuration are connected to a drive circuit, the drive circuit containing a DC voltage intermediate circuit and an inverter having a bridge circuit with circuit breakers including at least one positive circuit breaker and at least one negative circuit breaker, which comprises the steps of:

• switching on the at least one positive circuit breaker or the at least one negative circuit breaker of the inverter, while all other ones of the circuit breakers of the inverter are switched off;
• capturing a motor phase voltage of at least one selected motor phase of the motor phases with respect to a reference potential;
• and
• determining whether there is a motor phase interruption in one of the motor phases of the motor configuration on a basis of a voltage profile of the motor phase voltage captured.

A drive circuit for driving an electronically commutated motor, the drive circuit comprising:

• a DC voltage intermediate circuit;
• an inverter connected to said DC voltage intermediate circuit and having a bridge circuit with circuit breakers including at least one positive circuit breaker and at least one negative circuit breaker, and to said circuit breakers motor phases of a motor configuration containing the electronically commutated motor can be connected;
• a detection circuit for capturing a motor phase voltage of at least one selected motor phase of the motor phases with respect to a reference potential;
• a controller configured to individually switch said circuit breakers of said inverter on and off and to operate said detection circuit for capturing the motor phase voltage;
• and
• said controller configured to determine, on a basis of a voltage profile of the motor phase voltage captured, whether there is an insulation fault on one of the motor phases of the motor configuration and/or is configured to determine, on a basis of the voltage profile of the motor phase voltage, whether there is a motor phase interruption in one of the motor phases of the motor configuration.