Research On Digital Controlled Heating Power System Of Crystal's Preparation

The single crystal silicon growth furnace's heating power supply,which belongs to high power source whose output voltage is low while output current is large,is one of the most important components in the single crystal silicon preparation system.Generally,thyristor power supply can meet the requirements for heating power supply for preparing crystal,but it has the disadvantages of large volume,slow dynfamic response,low power supply efficiency,and serious harmonic pollution.Therefore,under the premise of satisfying industrial production,it is necessary to research on the heating power system for preparing crystal.Firstly,this paper compares and analyzes the single-module high-power power supply structure,the structure of multi-module parallel under single controller and the structure of multi-module parallel under multiple controllers.It is concluded that the structure of multi-module parallel under multiple controllers can thoroughly solve the current sharing problem of paralleled modules,which has the characteristics of good current sharing and high system reliability.Furthermore,the power circuit composed of a three-phase uncontrolled rectifier circuit,a ZVS-FB-PWM circuit,a high-frequency transformer,and a full-wave rectifier circuit is determined.Then,this paper introduces the working mode of each circuit in the power circuit,and detailed analyzes the working process of ZVS-FB-PWM circuit,the realization conditions of the soft switch and the sub-side duty cycle losing issue and solution,and power devices are selected after parameters optimization of them.Finally,the simulation system of the power module is built in the PSIM environment to verify the correctness of the device parameters and the effectiveness of current and voltage double closed loop PID control algorithm.The digital power controller based on STM32F334 microprocessor is designed and the control program is programmed.Building a prototype of fully digital controlled heating power source for preparing crystals,whose output power is 180kW+60kW,to fully test circuit design and devices selection.The results show that the power system is stable in operation,good in current sharing,high in conversion efficiency,low in harmonic content,and small in electromagnetic interference,which satisfies the technical requirements.