Modeling of electric machines for automotive applications using efficiency maps

In most industrial applications of motor drives, motors operate at one or a few predefined operating points. However in propulsion applications, the motor is used over the entire torque/speed range. Therefore, the motor has to be studied at all possible torque/speed combinations within the motor operating envelope. Efficiency maps are a convenient way to represent motor drive subsystem of a large, complex, system like a vehicle. Efficiency maps give the system engineer an idea about the torque/speed combinations at which a specific electrical motor drive is efficient, thus allowing for a more efficient design. In this report we look over the efficiency characteristics of motors that are most commonly used for propulsion applications. We also quantify typical load on motor drives in vehicles that use electric propulsion, namely Electric Vehicles (EV) and Hybrid Electric Vehicles (HEV).