Research On Charging And Discharging System For Lead-acid Batteries Based On Thyristor

Lead-acid battery is widely used in every field because of its outstanding advantages. It has become one of the most important parts of Electric vehicle and UPS.Both charge and diacharge are important for maintenance of battery.The charge and discharge functions are fulfilled with single control circuit.The thesis gives emphasis on expounding the electrochemical mechanism of Lead-acid battery in the process of charge and discharge,analyzing how voltage changes from both the inner and outer aspects.The studying object in the thesis is charge-discharge lead-acid battery device.The demands of charge-discharge device are analysed.Recent charge-discharge methods and control methods of charge-discharge are analysed.An integrated control method is proposed to judge the state of battery,which integrates voltage control, timing control. The total scheme is designed according to the performances of charge-discharge device.In the process of designing system, technique of phase-controlled power supply is adopted.The system is designed which is composed of one-phase full-bridge, thyristor is selected as the switch.And the control system is based on TMS320LF2407A chip. AC voltage,terminal voltage of battery and charge-discharge current are detected for protecting the system effectively. Through analyzing and processing the detected terminal voltage of battery and current in DSP, acquiring phased-shifted angelfor driving the gate of Thyristor.In the rectifier mode, charge is carried out; in the inverter mode, discharge is carried out.The design of system is presented particularly in two aspects of hardware and software.The principles of some circuits are analysed. Variable parameter PI control based on intelligent PI control are presented and analysed particularly, for DSP controllers combining the real-time processing capability with controller peripherals.Dynamic response and static error precision of intelligent PI control are better than conventional PI control.Finally, a sample of the system of battery charge and discharge is produced.Experimental waveforms of lead-acid battery voltage and charge and discharge current are given.The experiment shows that the control method is better, and the precision of charge and diacharge.It confirms the analysis above.