Design Of A High Power Factor Digital Control Boost AC-DC Constant Voltage Power Supply With Fast Dynamic Response

A high power factor digital control Boost AC-DC constant voltage power supply with fast dynamic response is designed in this thesis,which can be used to drive ultraviolet lamp(UV lamp).As a special light source which can provide precise energy radiation,UV lamp is widely used in semiconductor industry,medical,mechanical,food and other industries.In semiconductor industry,it is mainly used for thermo electronic wafers,blowing PETP bottles,reflow soldering equipment and dry fillers.In order to achieve more precise energy control,constant voltage driving of ultraviolet lamp is required to have fast dynamic response,Low ripple and other characteristics.With the development of society,the requirement for purity of circuit system is higher and higher,and the high power factor(PF)of circuit system becomes more and more important.Therefore,the constant voltage drive of ultraviolet lamp is required to have high PF.The high power factor digital control Boost AC-DC constant voltage power supply system with fast dynamic response which is designed in this thesis includes three parts: main topology,ADC circuit and digital controller.The main topology and ADC circuit are drawn into PCB board.The digital controller is realized by FPGA.The digital controller mainly includes five parts,prediction algorithm,PI(Proportion Integration)algorithms,current control algorithm,triangular wave PWM algorithm and soft start.Prediction algorithm can effectively eliminate the influence of ADC delay and duty cycle calculation delay of digital controller,thus improving the system bandwidth and dynamic response performance.PI algorithm firstly calculates the transfer functions of open-loop system and PI controller respectively.In order to meet the requirements of system bandwidth and total harmonic distortion rate,the proportional coefficient of PI controller is determined.In order to compensate the pole of open-loop system,the integral coefficient of the PI controller is determined,so that the system can get a good phase margin,and then make the output of the system to be stable.The duty cycle of the next cycle is determined by the current control algorithm for the purpose of input current's tracking the input voltage,so that the system can get a higher PF.Compared with other PFC control strategies,this algorithm has the advantage of simple structure and easy implementation.In order to make the system start smoothly and reduce the overshoot voltage of start-up time,the soft-start circuit is designed.The soft-start circuit increases the turn-on time of the switch cycle by cycle until the system output voltage reaches the reference voltage.The triangle-wave PWM algorithm is a modulation mode which divides the turn-on time of the switch into two parts and places them at both sides of the whole switch cycle.It is first time for this thesis to use this modulation mode for the prediction algorithm,which simplifies the prediction algorithm and improves the prediction accuracy and ADC sampling accuracy,so as to stabilize the output voltage,save resources and reduce costs.In this thesis,the whole system is simulated by Simulink and Modelsim,and the program is downloaded to the FPGA for hardware verification,which is the EP4CE6F17C8 of Altera Company.The results of simulation and hardware verification show that the design meets the design specifications,realizes high power factor,and the dynamic response performance of the whole system has been greatly improved.The system has output power of 300 W~230W,output voltage of 230 V,constant voltage accuracy of ±4% at full load,input AC frequency of 50 Hz,amplitude of 156 V~116V,switching frequency of 100 kHz,digital clock of 20 MHz,power factor of more than 0.95 and output voltage ripple of less than 4%.The linear adjustment rate of the system is ±6.5% and the load adjustment rate of the system is ±4.3%.