Research On Phase Shifted Full Bridge Soft Switching Electroplating Power Supply

With the development of science and technology,high power and high frequency electroplating power supply has become a hot topic.As the increase of the working frequency,the switching loss and the electromagnetic interference will become serious.In order to solve these issues,soft switching technology is the proposed to realize the switch of zero voltage or zero current,this technology will reduce the losses of switching and also improve the efficiency of power.Compared with the traditional electroplating power supply,the high frequency electroplating power supply is more efficient and the size becomes smaller.In addition,while the source current and current rating is equal,the converter output power is usually proportional to the number of power switch,so the full bridge converter is the largest power in dc converter,and have been widely used in the occasions of high power.In this thesis,the passive clamped phase shifted full bridge converter of zero voltage zero current is seen as the subject of study.Compared to the conventional converter of zero voltage zero current,this topology has a better gain of duty,and the loss of duty cycle can be reduced by designing the parameters of the auxiliary circuit reasonable,and then analyzes the operating modes and circuit characteristics of the topology under phase shifted control.On this basis,thesis give the conditions of leading leg to realize switch of zero voltage and lagging leg to realize switching of zero current,and pointed out that the soft switch conditions of the diode in auxiliary circuit.Secondly,On the basis of analyzing the small signal model of buck circuit,by introducing the concept of effective duty,and the small signal model of the passive clamped phase shifted full bridge converter of zero voltage zero current is established.Derived the transfer function of system.Based on it,the closed-loop controller of PID control and fuzzy control is designed.From the simulation,results show:compared to the PID control,the output voltage overshoot of the fuzzy control is smaller.The parameters of the main circuit components of the power supply are designed.Based on the open loop simulation analysis,established the voltage closed loop feedback control system.From the simulation,for the range of load changes,fuzzy control has better dynamic characteristics.Finally,On the basis of theoretical analysis,using TMS320F28335 DSP as the core of the control circuit and designed the hardware,including data sample circuit of voltage and current,drive circuit of IGBT,protection circuit of over-current and circuit of isolation.In addition,software of the electroplating power system is designed and give the flow diagram of corresponding program.