Basic Principle of Battery Electric Vehicles (BEV)

Battery Electric Vehicles use the energy stored in batteries for vehicle propulsion. The gasoline engine is replaced by an electric motor. The electric motor gets its power through a controller from rechargeable batteries. The heart of an electric car is the combination of electric motor, controller, and batteries. The accelerator pedal hooks to a pair of potentiometers (variable resistors), and these potentiometers provide the signal that tells the controller how much power it is supposed to deliver. The controller can deliver zero power (when the car is stopped), full power (when the driver floors the accelerator pedal), or any power level in between. There are mainly two kinds of arrangements namely DC Motor-Controller and AC Motor-Controller. In DC Motor-Controller arrangement a simple DC controller connected to the batteries and the DC motor.  The controller takes DC power from batteries and delivers it to the motor in a controlled way (Fig.1a). In AC Motor-Controller arrangement a simple AC controller connected to the batteries and the AC motor.  This controller converts DC supply from batteries to AC supply for AC motor. In addition controller provides a charging system for the batteries and a DC-to-DC converter to recharge the 12-volt accessory battery (Fig.1b).