Electric Vehicle Heating Management Techniques utilizing Drivetrain-Loss-Heating of Refrigerant

Paper in proceeding, 2022

Resistive cabin heaters can significantly reduce the driving range of battery electric vehicles in cold climate conditions. Heat pump solutions can mitigate this drawback, but these are also complemented with resistive heaters which are often unnecessary in warmer climates. This paper investigates different drivetrain-loss-heating techniques, which can be used as redundancy or as a replacement for the resistive heater. With the help of different software tools, the achievable electric drive unit (EDU) losses, considering the motor and inverter losses, of a Volkswagen ID.3 are simulated. When driving at lower speeds or standstill, the EDU losses can be regulated via the stator current magnitude. As demonstrated, this method increases the torque ripple, but the generated heat losses, varying from 5.8 kW to 7.9 kW, are sufficient to fulfill the cold climate heating requirements. When operated at standstill, a declutched motor can achieve comparable heat losses, but disconnectors are seldomly used in battery electric vehicles. When using balanced three-phase DC currents at standstill, the heat losses vary from 4.6 kW to 5.4 kW depending on the rotor position, which might not be sufficient to fulfill the required heating capacity at cold climates.