Research On The Precise Temperature Control System Of MPCVD Equipment

MPCVD,or microwave plasma chemical vapor deposition,is a common method for preparing diamond films.The temperature of the sample stage directly affects the yield and quality of the diamond film during the operation of the MPCVD equipment,and is a key factor affecting the preparation effect.In the current MPCVD equipment,the temperature control process is basically still controlled by the traditional PID algorithm or the PI algorithm.The traditional PID control algorithm is simple and easy to implement,but it is difficult to achieve good control effects for this kind of complex control process with many influencing factors,such as nonlinearity and large hysteresis.This paper designs a precise temperature control system for MPCVD equipment.The system combines fuzzy control and PID control to achieve a stable output of magnetron microwave power;combines BP neural network and PID to achieve automatic control of cooling water temperature;The generalized predictive control algorithm is applied to the temperature control of the sample stage of the MPCVD equipment.Field experiments have proved that a good control effect has been achieved.The temperature control of the sample stage is accurate to ±3 ?,which can meet the design requirements of the enterprise.In terms of hardware design,STM32F103RCT6 is selected as the core of the control system,and the overall circuit design of the temperature control system is carried out,including the main components of the system's power supply,signal acquisition circuit,control voltage output circuit,stepper motor drive circuit,and communication circuit.In terms of software design,the main program and subprogram modules of the system are designed based on the idea of time base,including the acquisition part of analog signals and digital signals,the control signal PWM output part,the motor drive part,the communication part and the parameter storage Part,and use the Visual Basic programming language on the Visual Studio platform to design the human-computer interaction software.Write a serial port program on the MATLAB software of the host computer to communicate with the system controller,and call Simulink inside the program to optimize the algorithm.Field tests and experiments have proved that the hardware circuit and software interface design of the system are correct,all parts can work normally,the control effect of the system is good,and the control accuracy of the sample stage temperature of the MPCVD equipment is improved.