A novel control strategy for multi-phase battery chargers without Hall-effect current sensors

Generally, one should use one large input capacitor rated from thousands of micro farads to ten-thousands of micro farads when applying reflex method for battery charger. However, large capacitor is very expensive. This paper proposes a novel control strategy with separate charging time to reduce the loading of the input capacitor, so that one may use a smaller input capacitor, and then reduce the cost. In addition, a new current detection scheme is also proposed by using a difference amplifier followed by a low pass filter instead of the Hall-effect current sensor for the current sensing of each phase, so that the cost of implementation can be greatly reduced. Simulations and experimental results are shown to verify the proposed charging scheme.