Research And Implementation In Series Resonant Inverter Chopper Tuning Work Based On FPGA

Because of induction heating technology with high temperature,high efficiency,high speed,heating temperature easy to control,easy to realize mechanization and automation,no air pollution,induction heating has now widely used in metal melting,heating,heat treatment and welding and other industrial process.But at present,a lot of industrial fields widely used induction heating power source controlled by analog circuit,control accuracy is not high,poor flexibility,system reliability is low.And digital circuit control precision,flexible software design,the whole control system is simple,reliable,and the digital control circuits of induction heating power supply is of great significance.Based on the series induction heating power supply as the research object,this paper briefly introduces the basic knowledge of induction heating and the induction heating technology development process,the control problem of induction heating also makes a brief introduction.Then analyze and formulate the composition of the power supply scheme,and analyzes the induction heating power supply of all kinds of work way,on the basis of comparing several methods of power regulation,in order to overcome composed of series resonant inverter induction heating power supply voltage regulator tuning phase shift work and tuning of the defects in the work,this paper proposes a control method of inverter chopper tuning work,under the condition of meet the frequency tracking,produced a four-way adjustable pulse width and in turn the inverter trigger pulse signal,by controlling the H bridge four switch element conduction time to accomplish the goals for output power adjustment.Due to the change of load parameters in induction heating process will cause the change of load resonant frequency,in order to ensure that perceptual quasi resonant induction heating power supply work in low status,the inverter control circuit must have the function of frequency tracking,need to design a kind of phase-locked loop circuit in the system.Traditional phase-locked loop vulnerable to grid voltage,the influence of factors such as temperature drift,the synchronous adjustment of the system is difficult to realize,this paper designs a digital phase-locked loop based on FPGA,the circuit of high precision control,flexible software design.And the trigger pulse signal respectively,lead before the trigger Angle and dead zone,this paper analyzed the function of the time and design;To describe in detail the working principle and circuit module,through the experimental results show that the pulse signal generated from the circuit to achieve the desired results.