Full Bridge Series Resonant Inverter Research Articles

Laboratory setup for teaching resonant converters and induction heating

In this study, a laboratory prototype is implemented for electrical and electronics engineering students to have theoretical and practical knowledge about the resonant power conversion and induction heating systems. For this purpose, a safe low voltage induction heater laboratory prototype with full bridge series resonant inverter is set up and tested with different workpieces. Experimental studies for different load types are achieved and quality factor, resonant frequency, maximum inverter current, inductance and resistance values are investigated. The unique value of this study is that students will have knowledge about second order circuits, resonant converters and learn what conditions affect the circuit parameters of an induction heater. The properties of induction heaters will also be learned on this circuit.

Resonant frequency tracking mode on eddy current pulsed thermography non-destructive testing

Eddy current pulsed thermography (ECPT) has been widely used in the field of non-destructive testing due to its safety, non-contact detection, high spatial resolution and intuitive results. Inductive excitation source is an important component of ECPT and provides high-frequency alternating current to drive the excitation coil. However, a resonant frequency distortion phenomenon exists in the excitation source during the detection process, which seriously affects the output power of the excitation source and the sample detection effect. This paper presents a fast resonant frequency tracking loop for full bridge series resonant inverter which is used to search the resonance frequency in real time through direct digital synthesizer (DDS) and all-digital phase-locked loop. Theoretical analysis and simulation are presented to explain the working principle of the loop. Then, an experimental prototype is manufactured which serves as an excitation source for the ECPT experimental system. Compared with traditional excitation sources, the prototype does not need a water-cooled device and the tracking speed can be adjusted by modifying the parameters of DDS. Finally, experiments have been conducted on both artificial slot of 45# steel and natural cracks of rail and stainless steel to investigate the influence of resonant frequency tracking speed on the crack detection. The results revealed that reducing the resonant frequency tracking time can efficiently improve defect detectability and the manufactured prototype showed more application potential. This article is part of the theme issue 'Advanced electromagnetic non-destructive evaluation and smart monitoring'.

Construction of a power electronic source for cold plasma generation

This paper presents the development of a high voltage and high-frequency power electronics source, for plasma generation, at atmospheric pressure and vacuum, using helium and air as working gases. The source design consists of an inductive (L) full bridge series resonant inverter at high frequency, where the control implemented allows varying duty cycle and frequency. Plasma generation is made by high voltage with the power signal applied on two electrodes, which provides a strong electric field that excites, and thus, ionize helium particles or air particles. The power electronic source operation was tested in different plasma reactor configurations (dielectric barrier discharge, double dielectric barrier discharge, and jet type discharge). The developed power electronics source shows a correct performance and generate a strong electric field to achieve the plasma discharges desired.

An Efficient Power Control Technique for High-Frequency Resonant Inverter in Induction Heating System

An efficacious and reliable power control technique has been developed which can be used to regulate the output power of a high-frequency full bridge series resonant inverter (HF-FBSRI) in an induction heating (IH) system. In this paper, a modified buck-boost converter is presented to control the DC link/bus voltage which maintains the IH system under resonant mode and optimizes the performance of the IH system. Controlled DC link/bus voltage has been applied to this HF- FBSRI to control the average output power in the IH system. Using this aimed control technique, a wide range of output powers has been controlled and consistent performance of the IH system has been achieved. ZVS switching technique has been used to reduce the switching losses. Varying average power has been obtained at different duty cycles ranging from 0.2 to 0.8 with variable DC link voltage and it has been corroborated using PSIM environment for an IH system rated at 5500W.

Precise tracking of highly nonlinear phase-shift full-bridge series resonant inverter via iterative learning control

This paper presents iterative learning control of the phase-shift full-bridge series-resonant inverter (PSFB-SRI). It has the merits of high conversion efficiency, medium-to-high power capacity, compact size, and low current–voltage stress on components, but the demerits of highly nonlinear dynamics that varies in a wide range depending on the operating points. The PSFB-SRI also suffers from a grid-voltage disturbance when it operates in grid-connected environment. To overcome these control problems, an iterative learning controller (ILC) supplemented with a proportional controller is developed and applied to the PSFB-SRI. Conventional proportional controller is used to improve the output current tracking performance. The ILC makes use of both previous-cycle and current-cycle learning terms which help the system output to converge to the reference trajectory. It is also simple in structure and easy to implement in practical applications. First-harmonic approximation of the PSFB-SRI model has been conducted and the resulting nonlinear large-signal model was used to construct the developed ILC. A detailed design guideline of the control parameters is provided. Numerical simulations validate the proposed control scheme, and experiments using a 500-W prototype demonstrate its feasibility.

Pulse Density Modulation Based Series Resonant Inverter Fed Induction Heater System

This paper deals with implementation of a multi-output Series Resonant Inverter(SRI) for induction heating applications, which uses pulse density modulation(PDM) control for full bridge Series resonant inverters for output voltage and power control. It ensures better efficiency performances than conventional control strategies. The proposed converter can be considered as a two output extension of a full bridge inverter. This full bridge inverter can control the two outputs, simultaneously and independently, up to their rated powers, which reduces the usage of number of components as compared with conventional method. It also ensures higher utilization of switches used for its operation. A two output full bridge series resonant inverter is simulated and implemented. The Experimental results are compared with the simulation results.

Improved Time Responses of PI & FL Controlled SEPIC Converter based Series Resonant Inverter fed Induction Heating System

This work deals with the Power Factor Corrected Single-Ended Primary Inductor Converter (PFC-SEPIC) based voltage fed closed loop full bridge series resonant induction heating system for household induction heating applications. The output voltage of the front end PFC-SEPIC converter fed series resonant inverter governs the controllers, which may be PI controller or Fuzzy Logic Controller (FLC). The analysis and comparison of time responses are presented in this paper. The PFC-SEPIC converter is used to improve the output power and the THD of source side current are compared for PI and FLC controllers. PFC-SEPIC converter maintains improved current and voltage at unity power factor through the input mains. The SEPIC converter based Voltage Fed Full Bridge Series Resonant Inverter (VFFBSRI) converts the voltage at a frequency of 10 kHz to a level suitable for household induction heating. A 1 kW SEPIC converter based VFFBSRI with RLC load is designed and simulated using MATLAB/ Simulink and hardware is fabricated.

Power Control of Asymmetrical Frequency Modulation in a Full-Bridge Series Resonant Inverter

The traditional power control schemes for induction heating device mainly focus on the pulse frequency modulation (PFM) and the pulse density modulation. But they cannot solve the problems of power control, efficiency, and load-adaption well. This paper presents and analyzes the asymmetrical frequency modulation (AFM) control scheme used in the full-bridge series resonant inverter. With the proposed AFM control technique, the output power is controlled by two variables: the operation frequency and the division factor. Better efficiency performance can be achieved in the medium and low output power range when compared with PFM. The principles as well as the zero-voltage switching condition of the AFM are explained and the power losses of switches are analyzed. A control algorithm that schedules the three control modes of AFM is experimentally verified with a digital signal processor based induction heating prototype. The load-adaption, noise and thermal distribution problem of switches are also analyzed.

CFAVC scheme for high frequency series resonant inverter-fed domestic induction heating system

This article presents the investigations on the constant frequency asymmetric voltage cancellation control in the AC–AC resonant converter-fed domestic induction heating system. Conventional fixed frequency control techniques used in the high frequency converters lead to non-zero voltage switching operation and reduced output power. The proposed control technique produces higher output power than the conventional fixed-frequency control strategies. In this control technique, zero-voltage-switching operation is maintained during different duty cycle operation for reduction in the switching losses. Complete analysis of the induction heating power supply system with asymmetric voltage cancellation control is discussed in this article. Simulation and experimental study on constant frequency asymmetric voltage cancellation (CFAVC)-controlled full bridge series resonant inverter is performed. Time domain simulation results for the open and closed loop of the system are obtained using MATLAB simulation tool. The simulation results prove the control of voltage and power in a wide range. PID controller-based closed loop control system achieves the voltage regulation of the proposed system for the step change in load. Hardware implementation of the system under CFAVC control is done using the embedded controller. The simulation and experimental results validate the performance of the CFAVC control technique for series resonant-based induction cooking system.

AC-chopper application for CW CO 2 laser

A microprocessor-based algorithm was developed to control the power supply to a CO 2 laser using an AC-chopper method. This system was connected directly to a CO 2 laser tube without the need for a dc–dc converter or the storage capacitance of a multilevel circuit. The typical CO 2 laser power supply system had a full-bridge series resonant inverter or voltage multiplier. AC-to-AC converter schemes using zero voltage switching (ZVS) can be used efficiently and economically for low and medium power applications. This paper reports the performance characteristics of a symmetrical AC-chopper technology that can maintain the quality of the ac output of a CO 2 laser tube, regardless of the amount of switching loss. The laser was operated to an output power, maximum system efficiency total gas mixture of 37.2 W, 92%, and CO 2:N 2:He=1:9:15, respectively. The laser system, AC-chopper power supply and its operation were examined.

Power Measurement by Output-Current Integration in Series Resonant Inverters

In many applications, efficiency and service quality are improved with an appropriate power control. This paper focuses on a power-measurement method designed to deal with medium/high frequencies (tens to hundreds of kilohertz). It requires a previous knowledge of application and exploits some characteristics of the power topology and control, in this case, a full-bridge series resonant inverter. It is a new method based on a low-cost analog circuit that integrates the high-frequency load current, in order to reduce the computational complexity of measuring power. Harmonic analysis is carried out to determine the A/D converter requirements, and the theoretical results are verified using a digital-signal-processor (DSP)-based experimental setup. The power measurement may be implemented on the microcontroller or low-performance DSP used to control the power stage, with an error below of 2% independent of the load and mains variations.

Analysis of Two Continuous Control Regions of Conventional Phase Shift and Transition Phase Shift for Induction Heating Inverter under ZVS and NON-ZVS Operation

This paper proposes an analysis of two continuous control regions of conventional phase shift and transition phase shift for a full-bridge series resonant inverter operating under zero voltage switching (ZVS) and nonzero voltage switching (NON-ZVS) conditions with the load of induction heating. A number of circuit operations for the cases of conventional phase-shift and transition phase-shift control regions under ZVS and NON-ZVS conditions are analyzed first. Various voltage and current equations of the operating circuits are then obtained and used for calculation of the waveforms with the aid of the MATLAB program. The calculated waveforms make possible the consideration of some important circuit parameters that are used to determine ZVS or NON-ZVS conditions. The theoretical results and the proposed method are also verified by experiments, using a prototype test set in our laboratory.

Efficiency Optimization in ZVS Series Resonant Inverters With Asymmetrical Voltage-Cancellation Control

This paper presents a time-domain analysis and a computerized search algorithm for optimizing the efficiency in zero-voltage switching (ZVS) full-bridge series resonant inverters with asymmetrical voltage-cancellation (AVC) control for different load quality factors. The optimum AVC control found allows all the switches to be turned on with zero voltage with the minimum switching frequency. In order to minimize losses, the switching frequency is kept as close as possible to resonance. The optimum AVC control is compared with previous fixed or narrow frequency range control strategies to show that it improves performance over all the output power range for different loads. The detailed steady-state analysis carried out here increases the precision of the first-harmonic analysis of a previous work, which is especially important with distorted output currents due to low load quality factors or highly asymmetrical modulation strategies. The theoretical results are verified experimentally.

Asymmetrical Voltage-Cancellation Control for Full-Bridge Series Resonant Inverters

This paper presents and analyzes the asymmetrical voltage-cancellation (AVC) control, a generalized control technique for resonant inverters. It is applied to the popular full-bridge series resonant inverter. The proposed control technique achieves better efficiency performances than conventional fixed-frequency control strategies, while considering zero-voltage-switching operation, output power and load variations. The theoretical results are verified experimentally, using a prototype for an induction-heating cooking appliance.

Induction-heating high-frequency inverters using static induction transistors

Voltage-Fed full-bridge series resonant inverters are described that use static induction transistors, and operate efficiently in the frequency range 100–1000 kHz. Trial inverters are considered for 100 kHz and/or 400kHz high-power induction-heating and melting power supplies. In addition, a quasi-resonant inverter suitable for radio-frequency applications is produced to diminish switching losses operating at 1 MHz or so. Both types of inverter are found to work safely with sufficiently high efficiency, feeding high output power.