A charger is usually referred to as a stationary current converter that uses power electronic semiconductor devices to convert alternating current(AC), which has a fixed voltage and frequency,into direct current(DC).It adopts constant current/constant voltage/small constant current intelligent three-stage charging method,which is characterized by high charging efficiency,simple operation,light weight and small size.The charger is widely used in various fields,especially in the field of life is widely used in cell phones,cameras and other common appliances.
The charger first receives AC power from the grid,and reduces the voltage to a range suitable for charging the equipment through the internal transformer.Next,a rectifier circuit converts the AC power to DC power,and then a filter circuit removes stray waves from the DC power.For lithium-ion battery chargers,a constant-current-voltage-limited charging method is usually used,i.e.,a constant charging current is maintained until the battery voltage reaches a certain value,and when the battery voltage reaches the highest value,a constant charging voltage is maintained until the battery is full.
Specifically,the DC power output after the power management module is converted into high-frequency AC power through the active crystal inverter,which is supplied to the primary winding.By coupling energy through 2 inductive coils,the current output from the secondary coil is converted into DC again through the receiving conversion circuit to charge the battery.Charging current is generally used about C2,that is,two hours charging rate,for example,500mAh battery using 250mA charging current,about two hours after the battery voltage reaches 4.2V,and then constant voltage charging.
