ABSTRACT The main objective of this work is to design a control strategy of a hybrid energy storage system (HESS) to switch the battery and ultracapacitor (UC) as per EV requirement. To achieve the objective, a math function based (MFB) controller has been designed by considering four math functions further those can individually be programmed according to the speed of the motor. The speed of an electric motor plays a vital during the changing of energy sources present in HESS, and the main function of designed MFB controller to regulate the pulse signals which is given to the switches present in the unidirectional converter (UDC) as well as a bidirectional converter (BDC). In this work, three different controllers’ proportional–integral controller (PI), proportional integral derivative (PID) controller, and fuzzy logic controller (FLC) are used individually for generating required pulse signals to the switches present in DC-DC converters. Finally, the proposed objective can be achieved by combining MFB individually with PI or PID or FLC made a separate hybrid controller. Comparative analysis has been made among three hybrid controllers based on different factors. The entire circuit can be implemented with three hybrid controllers separately in MATLAB/Simulink with four modes corresponding to the motor’s speed.