| With the development of electroplating industry,the market demand for electroplating power is higher and higher.The high reliability,high efficiency,high power density and control method of electroplating power supply are the research hotspot at present.The circuit of digital control electroplating power supply is simple,the development cost is relatively low,and it has good stability and reliability.In addition,in the application of low voltage and high current,the efficiency of diode rectifier in the secondary rectifier circuit is very low,which affects the efficiency of the whole machine.Synchronous rectifier technology can effectively solve this problem.For the design requirements of stability,reliability,high efficiency and low cost.In this paper,a digital control electroplating power supply with synchronous rectification technology is designed.The full load output power is 1200 W.Firstly,the working principle of full bridge DC converter and the working process in one switching cycle are analyzed,and the main power circuit,control circuit and synchronous rectifier circuit of the system are designed.Secondly,based on the average state space small signal model of the full bridge converter,the transfer function of the system is obtained.According to the transfer function characteristics of the system,the compensator is designed,the influence of the compensation network on the dynamic characteristics of the system is analyzed,and the control loop and control software of the converter are designed.The simulation model of the system is built with software,the hardware circuit design and control mode of the system are further verified and analyzed,the technical problems of parallel current sharing of synchronous rectifier in the application of high current and power are analyzed,and the measures to improve the parallel current sharing are proposed,and the same step rectifier is designed.In order to suppress the excessive voltage oscillation on the secondary side of the converter,the RCD buffer circuit is used to reduce the parasitic oscillation on the secondary side.In order to solve the problem of magnetic saturation caused by unbalanced circuit,this paper adopts the method of coupling capacitance in series on the primary side,which can solve the problem of magnetic saturation of transformer.Finally,the experiment shows that the designed prototype meets the design requirements.The system realizes the digital control output,the secondary realizes the synchronous rectification,and finally can output stably under the two modes of voltage stabilization and current stabilization.The efficiency of the whole machine is more than 85%,which is greatly improved compared with the diode rectification efficiency. |
