Half-bridge Inverter Research Articles

Integrating a new adaptive PV system for ozone production process

Available data from 2013 suggest that 17% of the global population does not have access to electricity, 95% of those live in sub-Saharan Africa and developing Asia, with sub-Saharan Africa leading with 80%. This lack of electrical power accessibility reduces the number of water sanitation facilities; so the population faces a constant life-threatening risk when it comes to drinkable water because water sources are often highly polluted with germs and bacteria. The main purpose of this study is the design and implementation of a water treatment system based on the ozone disinfection mechanism and powered by solar renewable energy. The particularity of this system is its low cost versus high efficiency, and the heart of the system is a half-bridge inverter built around 16F628A microcontroller connecting the PV panel to the ozone generator. An experimental study was conducted using polluted water to test the effectiveness of the filtering system.

A dynamic model of power metal-oxide-semiconductor field-effect transistor half-bridges for the fast simulation of switching induced electromagnetic emissions

ABSTRACT Hard switching of semiconductors is the main source of conducted electromagnetic emissions (EME) in pulse-width modulation (PWM) driven power inverters. The requirements on the electromagnetic compatibility grow with the increasing number of installed electric motor drives and inductive power converters. An accurate prediction of the conducted EME requires a model which considers the switching transition of the power semiconductors and the parasitic elements. This typically leads to complex SPICE models, which are hardly suitable for fast dynamic simulations and model-based controller design. This paper presents a compact mathematical model of a low voltage half-bridge inverter, which is based on large-signal models for the individual components and allows for the fast simulation of the conducted EME and switching losses. The high accuracy of the proposed mathematical model is demonstrated by measurement results. In particular, it is shown that the model is able to accurately predict the conducted electromagnetic emissions up to 100 MHz.

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.

Asymmetric isolated unidirectional multi-level DC-DC power converter

This paper proposes an asymmetric unidirectional isolated multi-level DC-DC power converter (AUIMLDDPC). A three-winding transformer (TWT) is used as the interface between a half-bridge inverter (HBI) and two full-bridge rectifiers (FBRs). The turn numbers for two secondary windings of TWT are not the same. Thus, it results in unequal DC output voltages of the two FBRs. A selection circuit is adopted to control the unequal DC output voltages of two FBRS to be connected in series or stand-alone, and thus, generates a non-zero two-level voltage to control the magnitude of the output DC voltage of the proposed AUIMLDDPC. An output L-C filter is applied to filter out the high frequency harmonic of the non-zero two-level voltage. The secondary windings with unequal turn numbers for TWT can reduce the voltage change of the non-zero two-level voltage. Therefore, it can reduce the L-C filter capacity. To validate the performance of the proposed AUIMLDDPC, a hardware prototype is developed. The experimental results are as expected.

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.

GaN-based LSK demodulators for wireless data receivers in high-temperature applications

GaN (gallium nitride)-based fully-integrated demodulators are presented. These modules, intended for wireless applications, target high-temperature (HT) environments including monitoring devices in aerospace. The presented demodulators are dedicated to recover Load-shift keying signals modulating a low carrier frequency to maximize power transfer efficiency and increase data transmission rate through metallic barriers. Logic gates are implemented and successfully tested at HT exceeding 400 °C. Proposed demodulators are built from half and full bridge rectifiers, comparators, voltage references and inverters, and operate at a minimum carrier frequency (fc) of 50 kHz. A demodulator based on a digital topology is proposed to cover MHz range fc. A complementary ±14 V supply voltage is required to operate the circuits. Reported post-layout simulation results validate the functionality and performance offered by the proposed demodulators over the 25 °C–400 °C temperature range. Also, a complete chip layout has been done, where the introduced demodulators occupy 10 mm2 of a GaN die area.

Research on Single-Switch Wireless Power Transfer System Based on SiC MOSFET

The traditional wireless power transfer circuit uses the full-bridge or half-bridge inverter, which has complex circuit and control and low reliability. To solve these problems, a single-switch LC resonant circuit is proposed, which is simple in structure and can realize zero voltage switching (ZVS) without the problem of shoot-through. The circuit parameters and working process are modeled and analyzed. However, due to the influence of resonance, the common Si devices can not meet the demand because of the high blocking voltage of the switch. For this purpose, the circuit characteristics of SiC-based devices are studied, and the differences of driving and temperature characteristics between SiC MOSFET and Si MOSFET are compared. Finally, a single switch wireless power transfer (WPT) platform based on SiC MOSFET is built, which proves that SiC devices have great advantages in the field of WPT.

Optimal Current Slew Rate Control for a Three-Phase MOSFET Inverter Driving a PMSM

The active control of the current slew rate of hard switched voltage source inverters is a common method to reduce the electromagnetic emissions, overshoot and ringing. In a previous work, the authors derived a model-based optimal slew rate control strategy which combines iterative learning control (ILC) with an adaptive feedforward control for a single half-bridge inverter. This control strategy minimizes the switching losses while the current slew rate stays within desired limits. This paper presents the required extensions of the current slew rate control strategy for a three-phase voltage source inverter driving a permanent magnet synchronous machine (PMSM). The extended control strategy is implemented on a rapid prototype test bench to verify the performance by a number of measurement results. The results show that the current slew rate of each phase is controlled separately within the defined limits while the switching losses are minimized, independent of the load current, the supply voltage and the temperature.

Power losses analysis in MOSFET 3-phase high current power inverter for automotive application area

Abstract This paper deals with analyzing losses of three-phase high current and low voltage inverter, which is intended for automotive applications. High current inverters are becoming more popular in automotive area due to increasing the number of high power electrical drives in cars and trucks. The less reliable and less efficient, usually mechanical drive systems are replaced for more effective and more reliable electrical drive systems. There are liquid pumps, HVAC blowers, turbochargers, etc. Total losses of the common inverters are divided into three main parts, conductive and joule losses, switching losses and additional losses. The highest part of losses usually generates power switches, in this case MOSFETs. The size of other part of losses is determined by parameters of used components, i.e. DC-link capacitors, shunt resistor sensors, etc. The power losses and efficiency of inverter are analyzed by using the simulation model in LTspice. The model of inverter contains spice models of MOSEFTs and DC-link capacitors. The parasitic components of high current and excitation traces are also included into model. The analyzed inverter contains only DC-link shunt resistor for current sensing purpose in order to minimize joule losses of shunt resistors. Joule losses of shunt resistor, DC-link capacitor losses, reverse polarity battery protection MOSFET and three-phase half-bridge inverter are analyzed from power losses and efficiency point of view. The final result of this paper describes the size of losses of power circuit and the value of efficiency of inverter, which the high current inverter is able to reach.

Modeling and Control of Inverter Zero-Voltage-Switching for Inductive Power Transfer System

It's very important to maintain the inverter zero-voltage-switching(ZVS) for inductive power transfer (IPT) system, especially for those high power applications. The ZVS condition can be obtained via regulating the inverter operating frequency of the IPT system. A modeling method based on the energy-amplitude and phase is proposed and corresponding controller is designed to maintain the inverter ZVS condition for IPT. The dynamic model of the ZVS for the half-bridge inverter is developed firstly. To facilitate the dynamic performance analysis and controller design, the original time-variant model is linearized with small-signal method at its operating point, which yields to a 4 order transfer function model. A PI controller which maintains ZVS condition via regulating the inverter operating frequency is designed based on the transfer function. An IPT prototype is built to verify the proposed theory. Experiments show that the controller traces the reference of the ZVS angle within 20 ms under various perturbation, which verifies the correction and effectiveness of the model and controller.

A New PV Converter for a High-Leg Delta Transformer Using Cooperative Control of Boost Converters and Inverters

This paper proposes a new high-efficiency photovoltaic (PV) converter for grid connection through a high-leg delta transformer. The converter is composed of a symmetrically connected boost converter and three half-bridge inverters. One of the three half-bridge inverters is connected to the boost converter, and the others are directly connected to the PV terminals. As a result, this circuit configuration enables to reduce the power losses in both boost converter and inverters. This paper also proposes a new cooperative control method between the symmetrically connected boost converter and inverter. The control method can reduce the average switching frequency to 75% of that in a conventional one, resulting in a great reduction in the switching power loss. Experimental results confirm that the proposed circuit configuration makes it possible to improve its European efficiency from 91.6% to 94.5%. Moreover, system performance is evaluated on the assumption of maximum power point tracking operation.

Study of Proportional Pressure Modulator on the Basis of Electromagnetic-Type Linear Motor

The paper deals with a workflow of a proportional pressure modulator equipped with a linear electric motor of electromagnetic type (LEMET). A schematic diagram consisting of a power supply and control system has been constructed to determine the performance of LEMET. The power supply system is a self-contained half-bridge inverter. The converter input is supplied with 12 V DC voltage. The motor phase is powered by an inverter which includes transistor switches and diodes. The control system of the autonomous inverter consists of two channels – a current limiting channel and a linear transfer channel. The study is based on the results of numerical and simulation modeling of LEMET workflows. Numerical simulation is performed and investigated by a finite element method in the FEMM environment. Geometry of the LEMET model lies in the region of air with an electromagnetic permeability of 1. An initial radius of the grid generation for the working gap area is 0.5 mm, while for other areas an adaptive generation method has been applied. In order to determine a continuous power function at any point within a current variation interval i and a displacement x current linkage and electromagnetic force functions have been approximated by polynomials use of the Curve Fitting application. The simulation LEMET model of a proportional modulator has been built in the MatLab Simulink environment. The implicit Runge-Kutta method using the secondorder inverse differentiation formulas with a variable step has been applied for solution of a mathematical model in the MatLab Simulink system. The equation of an electrical circuit for an inductor motor phase has been compiled according to the second law of Kirchhoff. The LEMET traction characteristics have been obtained by moving a locking and adjusting element (LCE) from 0 to 6 mm in steps of 1 mm while changing the MMF in the winding from 0 to 2 A in steps of 0.1 A. It has been established that in order to move the LCE by 6 mm with the speed of 40 mm/s with a resolution of 0.15 mm, the maximum value of the current in the LEMET winding is equal to 2.5 A. In this case the value of the electromagnetic force is 120 N. This makes it possible to improve an accuracy of the brake drive pressure regulation by 12.3 %. Solutions have been proposed to increase the LEMET speedwork. Characteristics of the engine have been described and numerical parameters of LEMET have been determined in the paper. The developed simulation model allows to investigate functional properties and dynamic characteristics of the proportional modulator with a relative error of 4.07 %.

A Phase Angle Self-Synchronization Topology for Parallel Operations of Multi-Inverters in High Frequency AC Distribution

—High frequency ac (HFAC) power distribution system (PDS) has been known as the effective alternative of dc power distribution system (DC PDS) because of its excellent advantages such as high power density, high efficiency, fast dynamic response and fewer conversion stages. Multiple HFAC inverters are operated in parallel to satisfy the source side requirements like high power grade, safety margin and reliability. In order to eliminate circulation current caused by the amplitude and phase differences among the inverters, the amplitude and phase of individual inverter are required to be synchronous. However, parallel controls become extremely complicated as amplitude and phase are coupled together in full-bridge inverter with traditional phase-shift modulation. In this paper, a controllable half-bridge LCLC resonant inverter and dual-PWM modulation are presented with phase angle self-synchronization. Control strategy is given for voltage adjusting and phase-amplitude decoupling. Besides, the resonant network normalization parameters and control angle is summarized to ensure soft-switching. The simulation model and experimental prototype are implemented with the output frequency of 25 kHz. The experiment results and theoretical analysis agree well to verify the features of the proposed inverter.

Disturbance Observer-based Proportional-type Position Tracking Controller for DC Motor

This article exhibits a nonlinear proportional-type position tracking controller for DC motors, taking the parameter and load variations into account. The proposed method makes two contributions. First, a first-order disturbance observer (DOB) is devised in order to exponentially estimate the disturbances caused by parameter and load uncertainties. Secondly, a proportional-type nonlinear position tracking controller is constructed by incorporating the resulting DOB in order to ensure two useful closed-loop properties; namely, performance recovery and offset-free properties without the tracking error integral actions. The experimental result confirms the efficacy of the proposed method where a 30-W DC motor is used with an half bridge inverter.

Current-fed dual-half-bridge converter directly connected with half-bridge inverter for residential photovoltaic system

A current-fed dual-half-bridge (CF-DHB) converter directly connected with a half-bridge (HB) inverter unit is proposed for residential photovoltaic power conversion systems. The proposed inverter requires only half as many switching devices as the full-bridge two-stage inverters and does not have to use a large dc-link capacitor. However, the converter unit suffers from 120-Hz dc-link voltage fluctuation and 60-Hz capacitor voltage unbalance, which degrade the control performance of the half-bridge inverter. To suppress both dc-link voltage fluctuation and capacitor voltage unbalance, we propose to use appropriate repetitive controllers, that are used to determine the nominal duty-ratio and the phase-shift. To make the proposed CF-DHB operate at the maximum power point (MPP), we use the incremental conductance method that offers smooth transition to MPP. Experimental results show that the proposed inverter system achieved high MPP tracking efficiency, low total harmonic distortion, high power conversion efficiency, and medium power capacity.

Active Gate Control in Half-Bridge Inverters Using Programmable Gate Driver ICs to Improve Both Surge Voltage and Converter Efficiency

The requirements for peripheral circuits of power converters are becoming more restrictive due to the enhancement of Si-based power devices and due to practical use of SiC device. In the design of modern high-speed switching converters, the stray inductances and capacitances both in the device package and in the gate drive circuit in addition to those in the main circuit of the power converter must be considered. In these situations, the gate driving technique represents the key technology for enhancement of high-speed switching ability of power devices, as there are design limitations to reduce the stray inductances and capacitances. So far, several active gate control methods have been proposed. Most conventional active gate drivers are configured using analog circuits such as transistors and diodes. Thus, it is difficult to reconfigure their control parameters to fit the stray inductances and capacitances after the implementation of power converter and gate circuits. As a solution to these problems, the authors have proposed a programmable gate driver IC, which is a digitally controlled circuit. This gate driver IC can control the gate current at 63 separate levels, operated by programmable fully digital 12-bit and clock signals. In this paper, an active gate current control based on the load current in a half-bridge inverter with two programmable gate driver ICs is demonstrated. This developed gate control is different to the general current feedback control followed the reference value. It is verified that the proposed active gate control can effectively improve the tradeoff relationship between the surge voltage and switching loss of the pulsewidth modulation half-bridge inverter circuit.

Single-Stage Converter Based on the Charge-Pump and Valley-Fill Concepts to Drive Power LEDs

This paper proposes a nonisolated single-stage electronic system for driving power LEDs using the charge-pump and valley-fill concepts. Both concepts are related to the topological configuration based on the integration of a full-wave rectifier at the input stage with a half-bridge inverter at the output, characterizing a single-stage system. The charge-pump configuration is used to reduce the LEDs’ current ripple. The valley fill is employed to limit the dc bus voltage at levels below the peak value of the input voltage but maintaining a high-power factor operation. Therefore, it is possible to use bus capacitors with reduced voltage ratings. The operating principle of the proposed converter, which includes three operating modes in steady state, is presented and analyzed. The design methodology and the experimental results are also presented so that the operational characteristics of the proposed system can be verified. A 47-W, 220-Vac input, 67 kHz, 93.5% peak-efficiency prototype is built and tested to validate the carried out analyses.

Tubular Fluorescent Lamps Detection Based on the Self-Oscillating Electronic Ballast

In this paper, the detection of T5 tubular fluorescent lamps (FLs) is carried out with a self-oscillating electronic ballast. The developed topology identifies and operates different lamps with their rated powers. A single-ended primary-inductor converter (SEPIC) is used for power factor correction (PFC), with a half-bridge inverter to supply the lamps. The lamps detection is realized by means of an analog electronic circuit. The command of the switches of the PFC and inverter stages is accomplished by the self-oscillating circuit. Experimental results, as well as an analysis of the data referring to compliance with the technical standard NBR 14418 are presented in relation to preheating of the T5 FLs electrodes.

Improvement of the mathematical model of single­phase half­bridge inverter in state­variable form

The mathematical model of the insulated-gate bipolar transistor in the IGBT module is improved due to the determination of analytical expressions for dynamic spurious capacitances of the device. The expressions are obtained by analytical differentiation of functions that approximate the dependence of the spurious capacitances of the transistor on the voltage between the collector and the emitter. The method of forming a mathematical model of the IGBT voltage inverter in the form of matrix differential equations of state in the Cauchy form and nonlinear equations is proposed. There are no restrictions on the number of transistors and the configuration of the circuit. The method is based on the matrix-topological method of electrical circuits analyzing. The application of this method is illustrated by the example of a single-phase half-bridge inverter with resistive load. The urgency of improving the mathematical model of the IGBT inverter is caused by the need to analyze the electrical safety of the state of the variable frequency circuit between the frequency converter and the motor. Existing models of frequency-controlled electric drives do not take into account a number of factors that significantly affect the accuracy of the simulation. Such factors include the dynamic nature of the IGBT spurious capacitances and the disconnection of one of the machine phases from the network during the dead time when switching adjacent power switches of the inverter. The obtained mathematical model differs from the well-known in advanced representation of separate elements by nonlinear differential equations and taking into account mutual influences. The proposed approach allows to investigate the high-frequency transient components of currents and voltages in electrical systems with semiconductor converters. This simplifies taking into account the recharging processes of the IGBT capacitances during a dead time when switching adjacent power switches in the model. The peculiarities of the IGBT inverter switching transients are revealed, in particular, the significant exceeding, more than twice, of the transistor current during opening the operating current at the end of the switching process.

Analysis of Fine Dust Removal Time Using Circular Hole Electrodes of Various Sizes by Corona Discharge

Corona discharge technology is used widely for air purification in laboratory experiments and industry. On the other hand, corona discharge technology has the disadvantage of requiring large-sized electrodes. Therefore, research is needed to reduce the size of the electrodes. In this study, circular hole aluminum electrodes and an air purifier system were designed to reduce the size of the electrodes. Several sets of power conversions were performed to generate a corona discharge. The system consisted of a half bridge inverter, step-up transformer, and Cockcroft Walton circuit. The range of input and output voltages was 30–70 V and 20–25 kV, respectively. A corona discharge was generated by the output voltage. The system could remove smoke in less time with a combination of 13 kHz and an electrode with a hole diameter of 0.2 cm than with the other combinations. The electrode hole diameter affected the removal time of species such as hydrogen carbon hydrogen oxygen (HCHO, formaldehyde), total volatile organic compounds (TVOC), and fine dust, which was confirmed by laboratory experiments. Mathematical derivation and experiments were carried out to prove the validity of the approach; the Clean Air Delivery Rate (CADR) index was 480 μm/m3.