Electric Vehicle modelling with MATLAB simulink

In this contemporary world electric vehicles are more appealing, where reducing carbon emissions and pollution is a growing concern. Electric vehicles store electricity on board with high-capacity battery packs. It is no surprise that fully electric vehicles comes with rechargeable battery and no gasoline engine. The battery power is used to run the electric motor and all onboard electronics.

Electric Vehicle Block Diagram

Battery: Battery provides electricity to power vehicle accessories.
Battery Management System: A battery management system (BMS) is an electronic system that manages the battery such as by protecting the battery monitoring its state, calculating secondary data, controlling its environment, authenticating it or balancing it.
Motor: Using power from the battery pack, motor drives the vehicles wheels
Controller: The electric vehicle controller is the electronics package that operates between the batteries and the motor to control the electric vehicle’s speed.
Transmission: Electric cars don’t require multi-speed transmissions because of the so-called “engine” in an electric car, an electric motor. Instead, they have just one gear.

Simulink Model

• Mechanical part:
  vehicle body
  Tires with break
  Gears
• Electrical part:
  motor
  power converter
  PWM controller
• Battery:
  battery
  battery management system

Vehicle Block
The model uses a Vehicle Body, four Tires and a simple Gear.

Motor and Power Control Block
Components needed are a DC motor, H-Bridge and a controlled PWM Voltage, which produces pulse-width modulated signals to control voltage fed to H-Bridge as per requirements. Regenerative breaking approach is added.

Battery pack and Power converter
The model uses a battery and an SoC(state of charge) calculation block.
*The state of charge (SOC) of a cell denotes the capacity that is currently available as a function of the rated capacity. The value of the SOC varies between 0% and 100%.

Simulation performed using FTP75 drive cycle at wide open throttle condition

The speed comparison curve exhibit a fair response level of model trying to deliver required performance to meet the acceleration and deceleration commands.

Vehicle Parameters

Power and Torque requirements

The forces acting on the car are caused by internal, tire, and air resistance. The resultant of these forces, the total drag force, FD, can be estimated by the following equation:

power=force*velocity~18KWh

Torque=(efficiency*power input)/(angular velocity)~140Nm

According to the simulation results the vehicle speed and the cycle were the same.

At a fundamental level, electric cars offer a dramatically lower operating cost compared to conventional internal combustion engines. Yes, electric vehicles is a near future wave!