System and method for temperature estimation of inverter ac power bus

A method of operating a vehicle having a power inverter module, an electric motor configured to generate torque, and a controller having a processor and tangible, non-transitory memory, the method comprising:

• coupling an alternating current (AC) power bus to the power inverter module, the AC power bus having a plurality of busbars for conducting an AC current having multiple phases;
• coupling the AC power bus to a stator in the electric motor;
• positioning the plurality of busbars to be in respective thermal contact with an inverter coolant and motor oil;
• determining an estimated temperature of the AC power bus for each of the multiple phases of the AC current based on a plurality of factors, the plurality of factors including an oil flow rate of the motor oil and a coolant flow rate of the inverter coolant;
• and
• controlling operation of the vehicle based in part on a highest one of the estimated temperature for the multiple phases.

A motor vehicle comprising:

• a rechargeable energy storage system (RESS);
• a power inverter module adapted to receive DC voltage from the RESS;
• an alternating current (AC) power bus coupled to the power inverter module, the AC power bus having a plurality of busbars for conducting an AC current having multiple phases;
• an electric motor configured to generate torque to propel the vehicle, the AC power bus being coupled to a stator in the electric motor;
• an inverter coolant and motor oil in respective direct or indirect thermal contact with the plurality of busbars;
• a controller adapted to determine an estimated temperature of the AC power bus for each of the multiple phases of the AC current based on a plurality of factors, the controller having a processor and tangible, non-transitory memory on which instructions are recorded;
• wherein the plurality of factors includes an oil flow rate of the motor oil and a coolant flow rate of the inverter coolant;
• and
• wherein the controller is adapted to control operation of the vehicle based in part on a highest one of the estimated temperatures of the multiple phases.