Torque steering control of 4-wheel drive electric vehicle

The concept of a 4-wheel drive system for an electric vehicle is presented. This drive concept with four induction motors, one driving each wheel, allows the omission of the rear axle including the conventional differential gears. The drive has characteristics which can be compared with a 4-wheel steering system. The investigation of a single-track model of the vehicle leads to very similar transfer functions for both systems. A yaw motion control is implemented together with a drag-torque control of the wheels. Each block of the control is part of a hierarchy. Simulations performed with a more detailed nonlinear model show very good correspondence with the simplified model, and performance evaluation is based on an experimental study on a 4-wheel drive electric vehicle.