A versatile control modulator for optimal bidirectional battery charging

This paper presents a versatile control modulator (VCM) for optimal bi-directional battery charging. The VCM is capable of adapting to all the existing optimum battery charging techniques, i.e., Constant Current (CC)-Constant Voltage (CV) charging (two- mode charging), Pulse charging, and Reflex charging. The VCM is capable of testing the chargeability of a deeply discharged battery as well. The proposed VCM enables the converter to work as a current source with a controlled output current, when the battery state-of-charge (SOC) is below a predefined reference level and automatically reverts to a voltage source with the controlled output voltage, when the battery SOC exceeds a predefined reference level. Current feed-back clamping, used in the VCM ensures that the error amplifier never gets saturated and the transition between CC to CV mode is smooth and fast. Experimental and simulation results verify the operation of the proposed VCM on a 250 W bi-directional buck/boost converter with coupled inductor.