TABLE OF CONTENTS Electric machines find a place in conventional vehicles as starters and alternators. The former boost the engine to reach its idle speed and to start delivering torque. The latter produce electricity to charge the 12 V battery and to feed the electric auxiliary loads. In electric and hybrid-electric vehicles, the electric machine is a key component. Usually it is a reversible machine, which can operate in different ways: (1) convert the electrical power from the battery into mechanical power to drive the vehicle, (2) convert the mechanical power from the engine into electrical power to recharge the battery, and (3) recuperate mechanical power available at the drive train to recharge the battery (regenerative braking). The latter two modes are generator modes. In parallel hybrid vehicles and in electric vehicles the two functions can be fulfilled in principle by a single machine. In series hybrid vehicles and in combined hybrid vehicles two different machines are needed, the generator usually being a second reversible machine, smaller than the traction motor.
Characteristics of a good HEV motor include generally high efficiency, low cost, high specific power, good controllability, fault tolerance, low noise, and uniformity of operation (low torque fluctuations).
Electric motors basically can be organized in two main categories: direct-current (DC) motors and alternating-current (AC) motors (see Fig. 4.12). All types of motors have a stationary part, called the stator, and a rotating part, called the rotor. The latter is connected to the output shaft on which the motor torque...
