Research On Harmonic Suppression Of Parallel Resonant Induction-Heating Device Based On Buck Converter

The topological structure of the parallel resonant induction-heating device determines that its input terminal needs to introduce a larger inductance to achieve approximately constant current source input,however,the smooth effect of the inductor on the current leads to the distortion of the supply current and causes harmonic pollution to the grid.As the harmonic suppression of parallel resonant induction-heating is usually based on the combination of double power supply and double rectifier bridge,it makes the harmonic suppression structure more complex.At the same time,compared to series resonant induction-heating device,there is little research on harmonic suppression of parallel resonant induction-heating device.Therefore,with the purpose of realizing the harmonic suppression of parallel resonant induction-heating device,in this paper,the harmonic suppression of parallel resonant induction-heating device was studied based on small power parallel resonant induction-heating device.Based on the analysis of the existing harmonic suppression methods,the Buck active power factor correction with LC filter was introduced into this paper,and the harmonic suppression system of parallel resonant induction-heating device was designed.In view of the disturbance for the harmonic suppression which is caused by the equivalent time-varying load characteristic of parallel resonant induction-heating device,an equivalent time-varying load disturbance cancellation scheme was proposed to guarantee the stable operation of above harmonic suppression system and to reduce the difficulty of harmonic suppression.In view of the dead zone problem of Buck active power factor correction system with LC filter and its influence on harmonic suppression,an inherent dead time cancellation scheme was proposed to optimize the harmonic suppression effect and to improve the output voltage range of Buck active power factor correction with LC filter.In this paper,the operating characteristics of harmonic suppression system under discontinuous capacitive voltage mode(DCVM)were analyzed.Then,based on the switching cycle division and the switching period averaging description of internal state of the system,a DCVM model which can reflect the original nonlinear characteristic of the system was established,and the rationality of the model was verified by simulation.In view of the nonlinear characteristics of the system model,a passive control was introduced in this paper,then,the passivity of the system was analyzed and the feasibility of the algorithm was proved.Based on the derivation of the system state error model and the harmonic suppression target,the passivity-based control law of the system was designed by using the feedback passivity method,and the convergence of the internal state of the system under the control law was also investigated.Finally,the simulation circuit of harmonic suppression system of parallel resonant induction-heating device was built in MATLAB/Simulink/SimPowerSystem.The simulation results show that the equivalent time-varying load disturbance and the inherent dead zone of the system have been eliminated,the system has realized the harmonic suppression well.In addition,the optimization of Buck power factor correction also has been realized while improving the system power factor.