Half-bridge Series-resonant Inverter Research Articles

Enhanced Half Bridge Series Resonant Inverter for Induction Cap Sealing with Controlled load adaptation

Enhanced Half Bridge Series Resonant Inverter for Induction Cap Sealing with Controlled load adaptation

A Comparative Evaluation of Wide-Bandgap Semiconductors for High-Performance Domestic Induction Heating

This paper presents a comparative evaluation of wide-bandgap power semiconductor devices for domestic induction heating application, which is currently a serious alternative to traditional heating techniques. In the induction heating system, the power transferred to the output depends on the equivalent resistance of the load, and the resistance depends on the operating frequency. Due to the switching characteristics of wide-bandgap power semiconductor devices, an induction heating system can be operated at higher operating frequencies. In this study, SiC and Si semiconductor devices are used in the comparison. These devices are compared according to different evaluation issues such as the turn-off energy losses, turn-off times, current fall time, the power losses of the internal diodes, and the conduction voltage drops issues. To perform the proposed evaluation, the series-resonant half-bridge inverter, which is frequently used in state-of-the-art induction heating systems, has been selected. The device suitability in an induction heating system is analyzed with the help of a test circuit. A comparison is made in terms of criteria determined by using the selected switches in the experimental circuit, which is operated in the 200 W to 1800 W power range and 45 kHz to 125 kHz switching frequency range. System efficiency is measured as 97.3% when Si IGBT is used. In the case of using SiC cascode JFET, the efficiency of the system is increased up to 99%.

Design Methodology of Series Resonant Half Bridge Inverter for Induction Cooker

Design Methodology of Series Resonant Half Bridge Inverter for Induction Cooker

A Dual-Resonant Topology-Reconfigurable Inverter for All-Metal Induction Heating

Traditionally, domestic induction heating (IH) is designed to heat the ferromagnetic (FM) pan. However, it is incompetent to heat the non-FM (NFM) pan since the small equivalent resistance of the pan will easily result in overcurrent on the inverter. Inspired by the compensation network in the wireless power transfer (WPT), the series–parallel resonance (SPR) network with a relay switch is newly integrated into the IH technology to develop a dual-resonant topology-reconfigurable inverter for all-metal IH. The proposed system can be purposely configured to a half-bridge series resonant inverter with the pulse width modulation (PWM) to heat the FM pan, or a full-bridge SPR-based inverter with the phase shift control (PSC) to heat the NFM pan, respectively. Moreover, the output–input current gain of the SPR network equals the heating-coil quality factor, thereby readily eliminating the overcurrent issue of the inverter. For exemplification, a 1-kW prototype has been built with system efficiencies of 94.32% and 91.05% for heating FM and NFM pans, respectively. Finally, the proposed system can be evolved to achieve automatic load detection and impedance matching to ensure uninterrupted resonance. Both the calculated and measured results are given to validate the flexibility and feasibility of the proposed system.

Induction Heating in Domestic Cooking and Industrial Melting Applications: A Systematic Review on Modelling, Converter Topologies and Control Schemes

In the current scenario, power electronic device-based induction heating (IH) technologies are widely employed in domestic cooking, industrial melting and medical applications. These IH applications are designed using different converter topologies, modulation and control techniques. This review article mainly focuses on the modelling of half-bridge series resonant inverter, electrical and thermal model of IH load. This review also analyses the performance of the converter topologies based on the power conversion stages, switching frequency, power rating, power density, control range, modulation techniques, load handling capacity and efficiency. Moreover, this paper provides insight into the future of IH application, with respect to the adaptation of wide band-gap power semiconductor materials, multi-output topologies, variable-frequency control schemes with minimum losses and filters designed to improve source-side power factor. With the identified research gap in the literature, an attempt has also been made to develop a new hybrid modulation technique, to achieve a wide range of power control with high efficiency. A 100 W full-bridge inverter prototype is realised both in simulation and hardware, with various modulation schemes using a PIC16F877A microcontroller. The results are compared with existing techniques and the comparisons reveal that the proposed scheme is highly viable and effective for the rendered applications.

Input voltage selection method of half-bridge series resonant inverters for all-metal induction heating applications using high turn-numbered coils

All-metal induction heating (IH) systems have been introduced to heat both ferromagnetic and non-ferromagnetic pots using dual resonant frequencies. They are designed for heating ferromagnetic pots using a first harmonic operation mode (FHOM) and for heating the non-ferromagnetic pots using a third harmonic operation mode (THOM). All-metal IH systems employing dual resonant frequencies consist of an IH inverter and a power factor correction (PFC) circuit to transfer desired power to pots by increasing the input voltage of the IH inverter. In this paper, the input voltage is designed to obtain an efficiency-optimized operating point. To obtain an appropriate input voltage, power loss analyses are conducted using first harmonic approximation (FHA). Based on analysis results, the input voltage of the IH inverter can be selected to improve its power conversion efficiency. A 2-kW half-bridge series resonant inverter prototype is implemented to verify the effectiveness of the proposed design by heating ferromagnetic pots using the FHOM with a 2-kW transfer power and by heating non-ferromagnetic pots using the THOM with a 1-kW transfer power.

Phase-Locked Loop-Based Asymmetric Voltage Cancellation for the Power Control in Dual Half-Bridge Series Resonant Inverter Sharing Common Capacitor for Induction Heating Applications

This work aims at suggesting a frequency tracking system for a dual half-bridge series resonant inverter applied to induction heating (IH) system. The modulation technique incorporated is asymmetric voltage cancellation method. In this new tuning method, the control range is enhanced to the whole range of inverter operation. Also, the inverter discussed here is capable of driving two (dual) loads simultaneously compared to the conventional inverter feeding single load. Small-signal modeling of the dual-load IH system is discussed in this article to facilitate stability and controllability of the IH load. Also, the power control margin is determined with the necessary pole-zero plots. The simulation study of the proposed system is incorporated in the MATLAB/Simulink and also experimentally validated for the dual-coil induction cooking system.

Merits of SiC MOSFETs for high-frequency soft-switched converters, measurement verifications by both electrical and calorimetric methods

ABSTRACTThis paper quantifies the soft switching loss of a 1.2 kV SiC MOSFET module via a calorimetric method in a 78 kW full-bridge resonant inverter switched at approximately 200 kHz. By switching the SiC MOSFET just before the zero crossing of the current during turn-off and at perfect zero voltage during turn-on, this converter yielded an efficiency of roughly 99 %. Then, a simplified laboratory setup, including only a half-bridge series resonant inverter topology with split DC-link capacitors and an LC load, was built such that a real inverter operation was emulated, and thereby, turn-off loss was measured via an electrical method. A discrepancy of approximately 10 % is found between the two loss measurement methods, and the possible source for this difference is discussed. Furthermore, a standard double pulse test was also performed in an inductive clamped buck converter for measuring the hard switching loss. Finally, a comparison of losses obtained from the hard versus resonant topologies at the same load current was accomplished, which verifies the substantial benefits of the latter over the former. Thus, the merits of SiC MOSFETs for high frequency soft switched converters are demonstrated, which is the main contribution of this paper.

FPGA-Based Automatic Frequency-Controlled Resonant Inverter for Induction Heating System

This paper presents a frequency tracking control for the half-bridge high-frequency series resonant inverter-fed induction heating system. The aim of this research work is to obtain dynamic zero current switching in the switches of the inverter even under variation in the load. Closed loop frequency tracking control system is developed to track the resonant frequency during step change in load. The change in load is identified by sensing the phase angle between voltage and current. The error in the phase angle is used to track the frequency. Simulation of an open loop and closed loop IH systems has been performed. A simulation study is performed to verify the effect of controller. Simulation results of half-bridge series resonant inverter system with the proposed controller are presented to prove the performance of the developed control system. The results are validated with the prototype of system controlled by FPGA controller.

Steady-State Analysis and Modified Control Technique of a Capacitor Voltage Clamped Dual Half-Bridge Series Resonant Inverter

The paper discusses the technical problems, which are related to the application of the inverter configurations for electrotechnological purpose with power-limiting property. The examined capacitor voltage clamped dual half-bridge series-resonant inverter (CVCDHB-SRI) is a part of the class of inverters with improved load characteristics, which are characterized by stability in the operation of the power circuit, the power consumption is constant and independent from changes in the load. The present paper extends the investigation of the electromagnetic processes in steady-state mode of CVCDHB-SRI that supplies two different loads. A unified approach is introduced in the analysis of processes in steady-state mode, as well as, expressions for determination of the currents through the power devices and the resonant circuit components are obtained. A modified control technique for operating loads with different frequency and power is also discussed. Thus, the additional current overload of some of the transistors in the circuit is avoided. The commutation mechanism of the transistors enables zero-voltage and zero-current switching conditions. This results in increases the efficiency of the system and improves power quality and reduces the overall cost. The results of the analysis are confirmed by simulating with OrCad Pspice.

A Novel Power Control Technique for Series Resonant Inverter-Fed Induction Heating System with Fuzzy-Aided Digital Pulse Density Modulation Scheme

The research on Induction heating aided by power electronic control system is so vivacious in recent past. The selection of switching techniques remains to be the bottleneck for power engineering research as inappropriate selection may result in relentless switching loss, conduction loss, high current ripple, and lower power density. Therefore, modern design emphasizes multi-output resonant inverters, which not only have high efficiency but also facilitate resonant switching. This work proposes a single-stage ac–ac dual half-bridge series resonant inverter, with reduced number of switching devices. The proposed converter is controlled with fuzzy logic-aided digital pulse density modulation technique which aids in power control task. This intelligent power control scheme improves the system efficiency with less time-domain specifications. The simulation of the work is realized in MATLAB/Simulink arena, and hardware circuits are validated using dsPIC30F4011 microcontroller. The results reveal that the proposed schemes are highly viable and effective for the rendered application.

A closed-loop power controller model of series-resonant-inverter-fitted induction heating system

Abstract This paper presents a mathematical model of a power controller for a high-frequency induction heating system based on a modified half-bridge series resonant inverter. The output real power is precise over the heating coil, and this real power is processed as a feedback signal that contends a closed-loop topology with a proportional-integral-derivative controller. This technique enables both control of the closed-loop power and determination of the stability of the high-frequency inverter. Unlike the topologies of existing power controllers, the proposed topology enables direct control of the real power of the high-frequency inverter.

Reduced-Order Models of Series Resonant Inverters in Induction Heating Applications

From the controller design framework, a simple analytical model that captures the dominant behavior in the range of interest is the optimal. When modeling resonant circuits, complex mathematical models are obtained. These high-order models are not the most suitable for controller design. Although some assumptions can be made for simplifying these models, variable frequency operation or load uncertainty can make these premises no longer valid. In this study, a systematic modeling order reduction technique, slowly varying amplitude and phase (SVAP), is considered for obtaining simpler analytical models of resonant inverters. SVAP gives identical results as the classical model-order residualization technique from automatic control theory. A slight modification of SVAP, slowly varying amplitude derivative and phase (SVADP) is applied in this paper to obtain a better validity range. SVADP is validated for a half-bridge series resonant inverter and for a high-order plant, a dual-half bridge series resonant inverter giving analytical second-order transfer functions for both topologies. Simulation and experimental results are provided to show the validity range of the reduced-order models.

Single-stage unity power factor based electronic ballast

This paper deals with the design, modeling, analysis and implementation of unity power factor (UPF) based electronic ballast for a fluorescent lamp (FL). The proposed electronic ballast uses a boost AC–DC converter as a power factor corrector (PFC) to improve the power quality at the input ac mains. In this single-stage UPF based electronic ballast, boost PFC converter and a half bridge series resonant inverter (HBSRI) share a common power switch. Thus one power switch is reduced as compared to the conventional two-stage approach. The design, modeling, analysis and implementation of this topology were carried out in MATLAB-Simulink environment for a T8 36 W, 220 V, 50 Hz fluorescent lamp. The switching frequency was kept more than the resonant frequency of the inverter, to ensure the zero voltage switching (ZVS) operation of both power switches. This resulted in reduction of high frequency switching losses. The power quality parameters such as displacement power factor (DPF), distortion factor (DF), power factor (PF), crest factor (CF) and total harmonic distortion of ac mains current (THDi) were evaluated to analyze the performance of proposed electronic ballast. Test results on a developed prototype of PFC electronic ballast were included to validate the design and simulated results.

Characteristics analysis and library development for piezoelectric transformer to drive a ballast for a 35 W class fluorescent lamp using PSPICE modeling

PSPICE model driven by an electric equivalent circuit of a piezoelectric circuit is presented. In order to confirm this model to be effective, an independent model of cold cathode fluorescent lamp (CCFL) driving circuit is used to conduct simulations, leading to a precise modeling. A library is configured through modeling and its accuracy is verified through simulations for widely used and representative lamps such as CCFL, fluorescent lamps, HID lamps, and electrodeless fluorescent lamps. On the basis of experiments, a lamp simulation is also performed using PSPICE, which allows us to take advantage of the lamp library easily. Also, PSPICE model driven by an electric equivalent circuit of a piezoelectric transformer is presented. In order to confirm this model to be effective, an independent model of CCFL driving circuit is used to conduct simulations, leading to a precise modeling. In addition, a new type of electronic ballast is proposed, which allows 35 W-class (T5-class) fluorescent lamp to work. This system is built by a rectifier which has improved power factor and half-bridge series resonant inverter. Also, with size of 27.5 mm high, 27.5 mm wide and 2.5 mm thick, the produced piezoelectric transformer has a high step-up ratio, through which it is possible for the electric ballast circuit to be lighter, smaller and more efficient. After the produced ballast is used to drive the fluorescent lamp for 25 min, it yields 0.95 in power factor correction, 86% in efficiency, 35.07 W in output voltage and 20.5 °C in temperature increase while meeting the characteristics of the 35 W-class fluorescent lamp.

Analytical Model of the Half-Bridge Series Resonant Inverter for Improved Power Conversion Efficiency and Performance

Resonant power conversion is a key enabling technology of dc–dc conversion, inverters and contactless energy transfer systems. This paper presents an analytical model of the series resonant half-bridge topology aimed at improving the design, control, and efficiency of resonant power converters. The main contribution is a closed-form expression of the main converter waveforms as well as output power and efficiency. This model enables a fast design-space exploration, as well as the implementation of advanced control techniques using adaptive control or real-time emulation, significantly improving the converter operation. The analytical expressions presented have been applied and verified through a half-bridge series resonant inverter applied to induction heating applications, proving the accuracy and effectiveness of the proposed model.

Implementation of an FPGA-Based Online Hardware-in-the-Loop Emulator Using High-Level Synthesis Tools for Resonant Power Converters Applied to Induction Heating Appliances

This paper proposes a field-programmable-gate-array-based emulator of the series-resonant half-bridge inverter for measuring the inverter efficiency and detecting hard-switching conditions. The proposed emulator is able to compute the converter operating conditions and efficiency each mains half-cycle, providing useful information for the control unit. In addition, it is designed taking advantage of recent advances in high-level synthesis tools, which provides an optimized and straightforward implementation. The proposed emulator has been applied to an induction heating (IH) appliance as an example of efficient and environmentally friendly appliances with a major economic and social impact. The obtained results are compared with classical offline simulation and experimental measurements, proving that the proposed emulator achieves the required accuracy for the IH application. As a consequence, the proposed system can be used for improving the system safety and optimizing the converter efficiency and reliability.

Double Modulation Technique for a ZVS Self-Oscillating Half-Bridge Inverter

This paper proposes a simple power control scheme in order to convert the conventional nonadjustable self-oscillating half-bridge series-resonant inverter into an adjustable one. The proposed topology, based on a self-oscillating structure, can automatically ensure the turning on and the turning off of the switches without any external control. A simple modification in one of the gate drivers side circuit allows one to adjust the output power without compromising the simplicity, reliability, and low cost, which characterize the self-oscillating half-bridge inverter. Moreover, this topology achieves a stable and efficient zero-voltage switching over the entire operating range with a constant switching frequency; as a consequence, the inverter overall efficiency is significantly improved. Experimental results are proposed to validate the analysis and to demonstrate the performance of the proposed control scheme.

A high power factor and low crest factor Cuk converter for lighting systems

This paper deals with the analysis, design and simulation of power factor corrected (PFC), low crest factor (CF) electronic ballast for a compact fluorescent lamp (CFL). The proposed electronic ballast employs a Cuk buck-boost AC-DC converter as a power factor regulator (PFR) operating in discontinuous conduction mode (DCM). In the proposed electronic ballast, a half bridge series resonant inverter (SRI) is used to convert DC voltage into high frequency AC voltage. The design, modelling and simulation of this topology are carried out in MATLAB-Simulink software for an 18 W, 220 V, 50 Hz CFL. The zero voltage switching (ZVS) is used to reduce the switching losses at high operating frequency of 60 kHz. The power quality indices such as total harmonic distortion of AC mains current (THDi), power factor (PF), displacement power factor (DPF) and crest factor (CF) are estimated to study the behaviour of proposed electronic ballast.

Self-Oscillated Induction Heater for Absorption Cooler

Self oscillated resonant inverters have the advantages of low cost and simplicity. DC-AC power conversion can be achieved without using special drivers. In this study, self oscillated half bridge series resonant inverter topology is designed and applied to induction heater as a boiler part of home type absorption cooler system. The designed system has rapid and stable heating/cooling response compared to conventional resistance heated system. Self oscillated resonant inverter can achieve soft switching and maintain resonant tracking with simple and cheap drive circuit during all heating period. DOI: http://dx.doi.org/10.5755/j01.eee.19.10.5894