The Research On Model Of Mobile Wire Induction Heating Power And Control Algorithm

This thesis mainly focuses on building the accurate mathematical a model of mobilewire induction heating control system, studying optimal matching of induction heaters withdifferent load, investigating optimized control strategy of multivariable control system,electromagnetic field simulation, temperature field calculation and distribution modelbetween induction heater and heated strand while stabilization process, designing newall-digital frequency induction heating power hardware system in detail.Firstly, based on the detailed analysis of induction heating mechanism, the paperstudied the basic structure of the induction heating power supply system, completedaccurate modeling of the rectifiers, reactors, and inverter, proposed average model ofvoltage source-transformers-controlled rectifier, which reflected delay functions changedwith the opening angle of the rectifier from large to small and the influence of proceduresfor the arc and voltage source on the output voltage of the rectifier. Through the applicationof state-space averaging method, this thesis developed a single-phase inverter controlmodel with a linear time-invariant, and load disturbance unrelated.Secondly, load matching methods of the two common load resonance circuits(including the parallel resonant circuit and the series resonant circuit)were analyzed, a newelectrostatic coupling matching method to calculate the type of the mobile wire heatingpower was proposed; this thesis used the analytical method to get the load sensormathematical model of heated object which is a hollow cylinder, based on the analysis,derived the load sensor equivalent resistance and equivalent inductance formula; andthrough experimental methods parameters related to unloaded and load were all measuredand calculated respectively.Thirdly, considering the load temperature control that was most important aspects ofinduction heating power supply, the control scheme was developed based on cubic B-splinefuzzy control fitting algorithm. Compared with the traditional fuzzy control algorithm, themethod is not only with good dynamic characteristics, but also can effectively eliminatesystem stability state error, improve the control precision, and enhance anti-jammingcapability. Using the finite element method, the magnetic field and temperature fieldcoupling analysis of strand electromagnetic induction heating model was carried out byusing ANSYS, the electromagnetic fields and the eddy current field distribution under theapplied current density J of8×106A/m2, power frequency of2500Hz,3400Hz,5000Hz, andanalyzed of the influence of power frequency on the heating rate and the temperaturedifference between the core and surface, and provided basis for optimal power frequency.Finally, the new all-digital stabilization treatment system was designed, which usedPC104DX-586as the control center, data acquisition unit applied the12bit A/D analog capture card; a flexible all-digital pulse rectifier and inverter trigger unit were formed byCPLD with16counters combination; at the same time the power failure handler wasdesigned in orded to take protective measures in a timely manner through the LEDindicators when power failure, the testing results showed that the whole system has highreliability, pulse symmetry and high anti-interference ability, also with fast responsecharacteristics.