An Adaptable Feedback Clamped Optimal Battery Charger Using Fourth-Order Minimum-Phase Bidirectional DC-DC Converter

Many modern appliances including Electric Vehicles use two batteries at two different voltages. Charging one battery from the other requires bidirectional DC-DC converter that charges the battery with lower state of charge. In addition to the converter, a charging algorithm is required for the optimal charge of the battery. There are three-existing optimal battery charging techniques; 1) constant current-constant voltage (CC-CV) charging, 2) pulse charging, and 3) reflex charging. However, these charging techniques require different control circuits for their implementation. Moreover, in the conventional chargers, the changeover from CC to CV is unsmooth as the circuit does not remain in the feedback control during the transition. To address the above issues, a fourth-order minimum-phase bidirectional DC-DC converter (BDC) with an adaptable feedback clamped modulator is proposed in this paper. The proposed charger is capable of adapting to all the three-existing charging techniques by controlling the clamping voltage. The steady-state behavior of the BDC is verified through a 250 W prototype. Also, the performance of the charger using CC-CV charging is experimentally verified using a 6 V- 4.5 Ah lead-acid battery.