The Design And Realization Of Charging Manage With Switch Mode Power Supply IC

The lead-acid batteries have been widely applied for its long operational life, rich in raw materials, low production costs, stable voltage and other excellent features. In China, the lead-acid with matching electric cars’ output ranked first in the world for several consecutive years. But according to the statistics, due to improper charging manage-system for lead-acid batteries, lots of lead-acid battery’s operational life has less than half of its designed life. And now commonly used in cheapest charger with linear transformers, the efficiency and quality is undesirable, wasting electricity due to battery charging reached 50million kVAh each year. So, the switch mode power supply with charging management chip which can improve energy efficiency, reduce time of charging, does not affect the service life has become a major concern of the research.Firstly, the paper introduced the operating principle of lead-acid batteries, including the mechanism of chemical reactions that occur in the process of charge and discharge and electrical characteristics and analysis the advantages and disadvantages of common charging methods. Based on these existing methods, combined with Maas’s acceptable charging current curve theory, taking into account the complexity and cost of the product, decided to adopt a three-stage charging method for charging lead-acid batteries and the chips can automatically check the state of the battery to be charged, then select the appropriate charge mode. Using peak current-mode PWM controller for switching power supply of charger.The switch mode power supply with charging management chip integrated PWM controller and three-stage charging management unit. The chip improving the reliability and reduce the manufacturing cost of charger. Just adjust some add-ins resistance values can be used in different types of chargers. The chip was designed based on 2um 36V bipolar process, using Cadence Spectre S to simulate. The result shows that when the chip working under 10-30V, can provide maximum driving current up to 1A; maximum operating frequency up to 500KHz; maximum output pulse duty cycle up to 97%. For 48V designed voltage lead acid battery, maximum charging current is 2A on charging stage 1, constant charging voltage 57V on charging stage 2; float charge voltage is 52V, floating charge current is 0.45 A. Meanwhile the design and verification of the chip to be done concurrently.