| Lead acid batteries are widely used for now, but the smart chargers with automatic battery voltage detection function are very less. Most of common chargers on the market are only for single voltage charging application, such as only for 12 V, 24 V or 6V batteries,This will cause people have to use two different chargers for different batteries and it isn’t convenient. This paper introduces a type of charger design with the function of charging12 V and 24 V batteries. The charger adopts three stage mode charging design, which is to keep constant current with the first step, then constant voltage and float charging for the third step. This charging mode can protect battery and prolong battery’s life.Hardware design utilizes DC/DC flyback topology as current and voltage conversion.This charger is designed with high power density, small size, high efficiency and widely input voltage range. Sampling circuit of voltage and current is realized by ST company’s operational amplifier LM358. The PWM IC is Fairchild Company’s green IC SG6859 for power control application, this IC complies with Blue Angle power saving mode. Common mode inductor, differential capacitor, Y capacitor, PCB layout and transformer’s construction etc are utilized for EMC shield, and follow the EMC standard EN55014.Smart control device is ST company’s 8 bit general MCU STM8003K3,which controls and monitors the whole charging process, display the battery’s percent and battery type at same time through the program built in. This paper also describes how to distinguish12V&24V batteries in details. And gives the detailed description for computer interaction,battery voltage,percentage,battery type display, and three stage charging concept’s realization. MCU give error indication for wrong operation by operator and provide necessary protection as well and avoid damaging to person.
|
PDF Full Text Request