Power conversion device, motor control system, and diagnosis method for power conversion device

A motor control system comprising:

• a power conversion device including a power semiconductor module including a switching element;
• and
• a motor controlled by the power conversion device, wherein
• the power conversion device includes:
• a plurality of power semiconductor modules;
• a gate driver circuit configured to drive the switching element and transmit a response signal upon a switching operation of the switching element;
• a control unit device configured to output to the gate driver circuit an instruction signal for switching;
• a temperature detection unit configured to calculate a bonding temperature of the switching element based on the response signal to the instruction signal;
• a calculation unit configured to determine states of the power semiconductor modules according to the bonding temperature calculated by the temperature detection unit and the response signal;
• and
• a display unit configured to display states of the plurality of power semiconductor modules determined by the calculation unit for each of the plurality of power semiconductor modules.

A diagnosis method for a power conversion device including a power semiconductor module including a switching element, the diagnosis method for a power conversion device comprising:

• outputting an instruction signal for driving the switching element;
• calculating a bonding temperature of the switching element based on a response signal upon a switching operation of the switching element;
• determining an abnormality of the power semiconductor module according to the calculated bonding temperature and the instruction signal;
• generating the response signal based on a voltage between a gate and an emitter and a first drive voltage set value or a second drive voltage set value which is a switch-off reference voltage upon the switching operation of the switching element;
• and
• calculating a delay amount of the switching element based on the instruction signal and the response signal, so as to calculate the bonding temperature based on the delay amount.