Induction Heating for Variably Sized Ferrous and Non-Ferrous Materials through Load Modulation

Induction heating (IH) is a process of heating the electrically conducting materials especially ferromagnetic materials with the help of electromagnetic induction through generating heat in an object by eddy currents. A well-entrenched way of IH is to design a heating system pertaining to the usage of ferromagnetic materials such as stainless steel, iron, etc., which restricts the end user’s choice of using utensils made of ferromagnetic only. This research article proposes a new scheme of induction heating that is equally effective for heating ferromagnetic and non-ferromagnetic materials such as aluminium and copper. This is achieved by having a competent IH system that embodies a series resonant inverter and controller where a competent flexible load modulation (FLM) is deployed. FLM facilitates change in operating frequency in accordance with the type of material chosen for heating. The recent attempts by researchers on all metal IH have not addressed much on the variable shapes and sizes of the material, whereas this research attempts to address that issue as well. The proposed induction heating system is verified for a 2 kW system and is compatible with both industrial and domestic applications.

Study of the suitable value of dead-time between control signals of transistors for a series-resonant inverter with phase-shift control in induction heating systems

Induction heating provides contactless, energy-efficient, accurate, and fast heating of electrically conductive materials. Due to its advantages, IH is increasingly used in different fields such as industry, medicine, and the household sector. High-frequency transistor converters for the induction heating system are often based on series-resonant inverters. This paper analyzes a phase-shift-controlled voltage-source series-resonant inverter for induction heating systems. Mathematical analysis was performed in order to obtain the expressions that describe the output current of the phase-shift-controlled series-resonant inverter in the steady-state mode. Based on the analysis and the obtained expressions of the output current, analytical expressions of the dead-time between the transistors’ control signals of the SRI are obtained. The analytical expressions for determining the value of the dead-time are obtained for two cases: 1) zero value of the phase-shift; 2) the phase shift is greater than zero. To verify the obtained analytical expressions of the output current, validation was performed in the MATLAB/Simulink environment by comparing the peak current values. The verification showed the high accuracy of the obtained expressions, the deviation between the calculated and simulated values of the peak current is less than 0.1 %. The made simplifications of the dead-time expressions also were verified by calculation, the deviation between the calculated values of the drain-to-source voltage at the end of the commutation and the expected value is no more than 3.6 %. The SRI prototype has been designed and implemented in order to validate the analytical and simulation results

Designing of Improved Series Resonant Inverter with FPGA Controller for Heating Applications

Intensive utilization of Induction Heating (IH) innovations can be seen in numerous areas such as manufacturing industries, domestic or house hold and medicinal applications. The development of high switching frequency switches has encouraged the structure of high frequency inverters which are the key component of IH technology. Controlling the power output in a high frequency inverter for IH application is relatively complicated. This paper focuses on designing and developing a typical series resonance inverter and control it by FPGA-based controller. A MOSFET switch-based DC to AC converter is designed and Zero Voltage Switching (ZVS)-based switching strategy is accomplished to acquire less stress on switching devices and greater conversion efficiency. In this technique, secondary switched capacitor cell was proposed for resonant inverter of high frequency. To optimize the performance of the proposed inverter, the FPGA-based control system is implemented. Higher power density is the greatest advantage of this topology. The experimental and simulation model of the proposed series resonant inverter (SRI) for heating applications is developed and simulated using MATLAB/Simulink software.