Energy Saving Strategy with Steering Stability for an Electric Vehicle Driven by Multiple Motors

Traditional vehicle controller adopts a series energy saving and safty (SES) strategy, which independently designs vehicle stability system and power distribution system. However, traditional design method didn’t consider the interaction of each system. So, this research uses characteristics of motor to illustrate that direct yaw moment produced from vehicle stability system adversely affects the energy saving performance of the power distribution system. This research proposes energy saving strategy with steering stability for an electric vehicle driven by multiple motors, which adopts a parallel energy saving and safety (PES) strategy, and the goal is that the controller reduces direct yaw moment to achieve energy consumption improvement when vehicle has good stability. This research uses β-γ phase plane to judge vehicle stability, and it integrates with sliding mode control to design a vehicle stability system. This research verifies the strategy by model in the loop (MIL) and hardware in the loop (HIL) platform. Experimental results show that compare with SES strategy, PES strategy saves 1%~5% of energy when vehicle uses particle swarm optimization (PSO) as power distribution; and 4.5%~7% of energy when constant proportion (CP) is used as power distribution. Thus, the strategy of this research makes sure the controller can produce smaller direct yaw moment to stabilize the vehicle. The vehicle can then remain stable and achieve higher energy-saving performance.