Sensorless Control of Voltage Peaks in Class-E Single-Ended Resonant Inverter for Induction Heating Rice Cooker

Yongseung Oh,Wonsoek Oh,Jaeeul Yeon,Kyumin Cho,Ilya Galkin,Jayoon Kang

doi:10.3390/en14154545

Abstract

Single-ended (SE) resonant inverters are widely used as power converters for high-pressure rice cooker induction, with 1200 V insulated-gate bipolar transistors (IGBTs) being used as switching devices for kW-class products. When voltage fluctuations occur at the input stage of an SE resonant inverter, the resonant voltage applied to the IGBT can be directly affected, potentially exceeding the breakdown voltage of the IGBT, resulting in its failure. Consequently, the resonant voltage should be limited to below a safety threshold—hardware resonant voltage limiting methods are generally used to do so. This paper proposes a sensorless resonant voltage control method that limits the increase in the resonant voltage caused by overvoltage or supply voltage fluctuations. By calculating and predicting the resonance voltage through the analysis of the resonance circuit, the resonance voltage is controlled not to exceed the breakdown voltage of the IGBT. The experimental results of a 1.35 kW SE resonant inverter for a high-pressure induction heating rice cooker were used to verify the validity of the proposed sensorless resonant voltage limiting method.

Highlights

Induction heating—that is, the conversion of electrical energy into thermal energy using electromagnetic induction generated in conductive materials in alternating magnetic fields—has been used in the melting and heat treatment of metals in industry for many years [1]
Owing to the rapid progress of semiconductor devices and control systems in the 1980s, various high-frequency resonant inverter systems [2] have been developed as induction heating power sources
An insulated-gate bipolar transistor (IGBT) with a high breakdown voltage of 1200 V or more is typically used as the switching element [6,7]

Summary

Introduction

Induction heating—that is, the conversion of electrical energy into thermal energy using electromagnetic induction generated in conductive materials in alternating magnetic fields—has been used in the melting and heat treatment of metals in industry for many years [1]. Owing to the rapid progress of semiconductor devices and control systems in the 1980s, various high-frequency resonant inverter systems [2] have been developed as induction heating power sources. Their use has been increasing in industrial applications as well as in domestic cookers [3]. Inverters for domestic induction heating products, such as electric or induction rice cookers, usually have a capacity of 1–2 kW, using simple, low-cost, class-E single-ended (SE) resonant inverters [4] Such inverters require a semiconductor switch with a high breakdown voltage—deemed to be necessary because a capacitor is connected in parallel with a working coil to obtain voltage resonance, which is applied to a switch in series with a DC link capacitor [5]. An insulated-gate bipolar transistor (IGBT) with a high breakdown voltage of 1200 V or more is typically used as the switching element [6,7]

Methods

Results

Discussion

Conclusion