1 Induction Machine driven Electric Vehicles based on Fuzzy Logic Controllers Jemma J. Makrygiorgou and Antonio T. Alexandridis, Member, IEEE Abstract—Induction machine (IM) is an appealing solution for many drive systems mainly due to its low cost and main- tenance requirements. Since, however, the electromechanical structure of an electric vehicle (EV) is much more complex than a simple IM drive system, the design of an effective control for the entire system is a challenging issue. To this end, in this paper, the control capabilities of such an IM driven EV system are exploited in a twofold mode: On one side, closed- loop feedback controllers are proposed to regulate the internal system operating requirements as these are determined from the desired operation of the storage system and the effective use of the IM. On the other hand, a manual regulation of the vehicle motion is implemented, as it is practically applied by the car driver in accordance to his current decisions and the road circumstances. For the closed-loop scheme, fuzzy logic controllers (FLCs) are introduced due to the nonlinear and complex nature of the system. Nevertheless, the whole design includes a complete stability analysis of the entire system, thus overcoming an inherent weekness of FLC-based control design. In this manner, it is guaranteed a robust and stable operation of the system, while adverse control impacts are avoided. The simulation results fully confirm the theoretical analysis and verify a good system performance. Index Terms—Electric vehicle control, electric vehicle mod- elling, electrical drives, nonlinear analysis, fuzzy control. I. I NTRODUCTION In automotive industry, electric vehicles (EVs) turned up as an alternative to the conventional internal combustion engine vehicles for urban transportation. This seems to be an attractive future solution since many companies have based their entire models of cars around electricity due to environmental reasons, as zero emissions, lower noise pollution, high energy utilization, lower fuelling cost and low maintenance. In addition, although EVs basic drawback is the limited battery performance, new technologies offer the promise of extending the battery capacity and reducing the long re-fuelling time [1]. Furthermore, recent techno- logical advances in electricity power distribution and load management promise to facilitate the integration of EVs into electricity load [2,3]. In this frame, EVs can be used as distributed storage devices, feeding electricity stored in their batteries when its capacity is high, while EV-charging can be shifted to off-peak periods, in order to flatten the daily load curve and avoid high electricity prices. Jemma J. Makrygiorgou is with the Department of Electrical and Computer Engineering, University of Patras, Rion, 26500, Greece (email: dmak@upatras.gr) Antonio T. Alexandridis is with the Department of Electrical and Computer Engineering, University of Patras, Rion, 26500, Greece (email: a.t.alexandridis@ece.upatras.gr) Electric vehicle has, in general, a complex electromechan- ical stucture consisting of different types of power devices, with primary components the electric storage system (ESS) of batteries, the controlled power electronic devices, the motor and the transmission system [4,5,6]. Electrochemical batteries have been used as traditional sources of energy in EVs, with the lithium-ion (Li-ion) type to be the most popular today. In addition, the robust, maintenance free, low cost induction machines (IM) seems to become an appealing alternative to many developers, against the used in the majority of EV applications permanent magnet synchonous motor, due to its prohibitive future cost [7,8]. The requirement of an electric drive that controls the machine and delivers the requested power demands and feedback signals, is implemented by power electronic devices. To this end, a dc/dc bidirectional boost converter provides dc power convertion from high voltage to low voltage levels and vive versa and supports the different dc-loads that are fed at the dc-side, corresponding to vehicle lighting, safety and other system accessories. Also, a dc/ac three phase voltage source converter (VSC), delivers power at the desired voltage and frequency to the electric machine, providing the desired torque at the wheels in accordance to the driver commands, while in regeneration mode, processes power flow from the wheels to the ESS. It is evident that the power electronics circuit comprises of power semiconductor devices that saw a tremendous development over the past three decades and became a key in developing high performance and efficient power-train units for EV [9]. Finally, the transmission system is a key component for power transfer from the rotary motion of IM to the linear motion of the car. Unfortunately, the system complex structure, that is cer- tainly appeared with the nonlinear description of its dy- namics by a large-order model, have led to most heuris- tic and therefore non accurate control designs for EVs; these obviously cannot guarantee stability or non-adverse impacts between the different system components. In par- ticular, the majority of recent dynamic control designs take into consideration conventional nonlinear techniques, such as variable-voltage variable-frequency, field oriented control, direct/indirect torque control, e.t.c [10-13], which cannot ensure the entire system good performance since they are applied on seperate system components, while other designs are based on linear approximations, with main drawback the dependance from the operating point. Also, many researchers turned their interest in intelligent controls schemes that, un- fortunately, fully lack of stability analysis, while the demand of fast responding ac motor drives is many times implemented