Motor drive circuit, motor device, and moving vehicle

A motor drive circuit comprising:

• a DC power supply;
• power supply lines connected to the DC power supply;
• and
• an inverter which has a group of at least one upper arm switch device and another group of at least one lower arm switch device of one phase or of a plurality of phases connected in series between the power supply lines, and to which a motor is connected between the upper arm switch device and the lower arm switch device;
• the motor drive circuit includes a detection portion that detects insulation resistances of the motor drive circuit and the motor based on a power state on a previous stage with respect to the inverter, wherein
• the detection portion performs:
• a first detection operation for detecting the insulation resistance by using an output from the DC power supply in a state where all of the upper arm switch devices and all of the lower arm switch devices are kept in an off-state;
• and
• a second detection operation for detecting the insulation resistance by using the output from the DC power supply in a state where all of the upper arm switch devices of the one group or all of the lower arm switch devices of the other group are kept in the off-state and at least one of the upper arm switch devices of the one group or at least one of the lower arm switch devices of the other group is kept in an on-state.