Research On Switching Losses For Induction Heating Power Supply With Cycle Control

Compared to conventional flame heating and heat ef fect of electric current ,induction heating is a new heating m ethod. It is an advanced heating technology , which has m any obvious advantages such as highly efficient, material and ener gy saving, environmentally friendly, safely and so on. It is wildly used in metal smelting, heat treatment, welding and other processes, playing an important role in all sectors of industry. Induction heating device is an e ngineering system, the core com ponent is induction heating power supply , it can provi de energy for the induction heating, but the power capacity and the level of freque ncy and other perfor mance indicators is a sign, to determ ine the device is advan ced or not. The sign could af fect the development of induction heating.This paper introduces the basic knowledge of induction heating power supply , and the traditional induction heating parallel resonant load and series resonant load in detail, analyzes the similarities and differences between the electrostatic coupling and electromagnetic coupling, points out a new t ype of resonant lo ad (LLC load) to achieve load matching and gives a detailed analysis of the LLC load characteristics.When the induction heating power is applied in practice, to improve the capacity and operating frequency has become an urgent problem needed to be solved. Multiple inverter bridges in parallel operation can be used to ach ieve large capacity pow er supply, but the IGBT losses would be lar ger in this case. In order to increase power output and reduce the losses, m ultiple inve rter br idge will ope rates in pa rallel operation by the m ethod of cycle control in this paper. The turn-of f loss of IGBT would be analyzed in theoretical calcula tion and experimental verification, when it uses two control methods.In order to improve the accuracy of the experiment, the all-digital phas e-locked loop control system is designed in this paper, which takes FPGA as t he core. The control system provides two drive signals fo r the IGBT, which makes inverter bridge operate in the case of cycle control mode and norm al parallel control mode. Modules free to adjust the dead tim e and some of peripheral protection circuit of IGBT have been designed in this paper. Finally, we use P SPICE to b uilt simulation circuit to verify the advantages of cycle control m ethod in im proving power capacity and operating frequency.