Research On Digital Frequency Tracking Induction Heating Power

The traditional heating mode is the integration of resistance to heat coilobjects, the faults of this heating way has the high energy consumption, and thethermal efficiency is low, short life, work environment etc, and induction heatingtechnology compared to traditional heating mode advantage is self-evident. Butfor the electrical parameter especially the inductance could change along with therise of temperature when the loading coil is winding outside of the object heatedin induction mode, the inverter link of the power cannot work at the optimal state,which causes the resonant switch mode of the power out of work, At the sametime frequency tracking and power control can not very good combination tomake poor efficiency and accuracy. Induction heating power supply hasbackward in heating process control nowadays, and do not have the ability tocommunicate with the host computer and the ability to monitor. It also cannotcontrol online and reflect the cause of the malfunction timely.Basing on the above analysis, this thesis developed a set of high functionMCU as the core digital frequency tracking induction heating power, based onthe numerical control thought, building the digital human-computer interactionsystem, the power can be online adjust electric parameters, modify the power, theuse of high precision control strategy of frequency tracking, real-time trackingload frequency, so as to ensure the working efficiency of the power supply. At thesame time design the PC communication circuit and development based on Qtplatform PC monitoring software, convenient for observation and control when infact.IGBT is used as the switching device of the inverter in this thesis, the seriesresonant induction inverter is used as the main circuit of the design，set up themiddle and small power induction heating power supply. The development of frequency tracking control system adopts which the PIC18F4520microcontrollerand CD4046digital chip combined with the closed-loop control, developed andusing improved PFM power control strategy, improve the power supply heatingprecision and process effect, make induction heating power work in weakperceptual mode, so as to enhance the reliability of power supply. Also increasethe load detection, over current protection, over voltage protection, overtemperature protection, driver, dead band generator circuit, human-computerinteraction and other functional circuit. In software design, the modularprogramming methods was used, which makes the control software clarity andease of maintenance and upgrade.Finally, this article based on the development of the induction heating powerconduct the control experiment, the power supply could get nicer performance byimproved PFM mode. The frequency tracking system could keep frequencytracking rapidly and accurately, the better realize the power function is moreonline control by human interaction.