Nested FOPI and PI Controller Performance Comparison for Electric Vehicle Traction System

Electric Vehicles (EVs) are increasing in popularity due to climate change concerns, and pollution caused by fossil fuels across the globe. This stimulated advanced research in motor control algorithms for improving efficiency and performance of EVs. Induction Motors (IMs) are still the backbone of EVs drive systems due to their many qualities and cost effectiveness. This work investigates the use of nested Fractional-Order Proportional Integral (FOPI) and conventional integer order Proportional Integral (PI) controllers, and examines the effect of having these controllers in the inner and outer loops. Ziegler-Nichols (ZN) and Cohen-Coon (CC) rules are used for tuning the PI combinations on a prototype EV traction system consisting of an Indirect Field-Oriented Control (IFOC) based induction motor drive system. The speed regulation and power consumption for seven test cases with different combinations of FOPI, PI controllers used in these loops, are analyzed and compared. The findings of this research may help IM-based electric drives designers find an appropriate nested-configuration for the required applications when PI, FOPI controllers are involved.