Device Voltage Stress Research Articles

Study on LCL type IPT system power bi-directional push mode

Aiming at the working principle of inductive power transfer (IPT) technology, a bi-directional power conversion topology based on LCL type composite resonance is proposed. This topology introduces the advantages of LCL type resonance into the bi-directional power topology which has a resonance capacity larger than the single stage LC, it has a strong load adaptability, a smaller switching device voltage and current stress. Aiming at the LCL bi-directional power topology proposed, its working principle is introduced in detail, and the AC impedance model and mathematical model of the system are established. On this basis, the feasibility is verified by using the simulation experiment results.

Novel high step‐up dual switches converter with reduced power device voltage stress for distributed generation system

This study introduces a new dual switches converter with a high voltage gain and reduced power device voltage stress. Using a three-winding coupled inductor and voltage multiplier, the proposed converter achieves a high step-up voltage gain without a large duty cycle. However, unlike other converters with coupled inductor, the power device voltage stress in the proposed converter is dramatically reduced. The two clamped diodes not only alleviate the voltage spike across the metal–oxide–semiconductor field-effect transistor (MOSFET), but also reduce the diode reverse recovery issue. The efficiency can be improved as circuit allows the use of low on-resistance MOSFETs and Schottoky diodes in applications where this might not have been possible with conventional topologies. The basic operational principle and relevant theoretical analysis are presented in this study. Finally, practical results from a laboratory prototype are presented to verify the performance of the proposed converter.

Design and Implementation of a Novel Multilevel DC-AC Inverter

In this paper, a novel multilevel inverter for nine level application is proposed. The proposed multilevel inverter generates level ac output voltage with the appropriate gate signals' design. Also, the low-pass filter is used to reduce the total harmonic distortion of the sinusoidal output voltage. The switching losses and the voltage stress of power devices can be reduced in the proposed multilevel inverter. Multilevel inverter (MLI) plays a vital role in the field of power electronics and being widely used in many industrial and commercial applications. Moreover the advantages like high quality power output, low switching losses, low electro-magnetic interference (EMI) and high output voltage made multilevel inverter as a powerful solution converter topology. The multilevel inverter topology is the proper option from the point of view of modularity and simplicity of control. Main disadvantage of multilevel configuration is increase in number of power semiconductor switches and its complexity to design gate driver circuit individually, its cost and switching losses. Complexity of the induction motor system reduces reliability of the inverter. In this project, it is proposed to employ a new technique to obtain a multilevel output using less number of power semiconductor switches when compared to ordinary multilevel inverter, Voltage source converters are also required for various industrial applications, smart induction motor drive applications etc. Due to high power requirement in these applications, using one power semiconductor switch directly is not advisable. For high power and medium voltage applications multilevel converters are introduced.

A PWM Strategies for Diode Assisted NPC-MLI to Obtain Maximum Voltage Gain for EV Application

The projected diode assisted Neutral Point Diode Clamed (NPC-MLI) with the photovoltaic system produces a maximum voltage gain that is comparatively higher than those of other boost conversion techniques. This paper mainly explores vector selection approach pulse-width modulation (PWM) strategies for diode-assisted NPC-MLI to obtain a maximum voltage gain without compromising in waveform quality. To obtain a high voltage gain maximum utilization of dc-link voltage and stress on the power switches must be reduced. From the above issues in the diode assisted NPC-MLI leads to vector selection approach PWM technique to perform capacitive charging in parallel and discharging in series to obtain maximum voltage gain. The operation principle and the relationship of voltage gain versus voltage boost duty ratio and switching device voltage stress versus voltage gain are theoretically investigated in detail. Owing to better performance, diode-assisted NPC-MLI is more promising and competitive topology for wide range dc/ac power conversion in a renewable energy application. Furthermore, theoretically investigated are validated via simulation and experimental results.

High-Power Multilevel Step-Up DC/DC Converter for Offshore Wind Energy Systems

This paper presents a multilevel step-up dc/dc converter for dc-grid-based offshore wind energy conversion applications. The main features of the proposed multilevel converter are as follows: 1) the voltage stress of the power devices can be reduced, making it suitable for high-voltage applications; 2) the boost inductor can be reduced significantly, leading to the outstanding dynamic performance; and 3) high-voltage gain can be obtained and thus is well-suited for high-gain applications. Theoretical analysis was carried out for a four-level step-up converter, based on which, the converter can be extended to any arbitrary number of levels. The proposed four-level converter was verified by a simulation and evaluated by comparing with a conventional multilevel dc/dc converter in terms of the component stress and power device count. The developed topology was implemented on a 2-kW prototype converter to evaluate its feasibility.

Non-isolated high gain DC-DC converter by quadratic boost converter and voltage multiplier cell

Abstract A novel non-isolated DC-DC converter is proposed by combining quadratic boost converter with voltage multiplier cell. The proposed converter has low semiconductor device voltage stress and switch utilization factor is high. The superiority of the converter is voltage stress of the semiconductor devices depends on voltage multiplier (VM) cell. By increasing the VM cell the stresses across the devices reduce drastically. The proposed converter has same number of components compared to certain voltage lift converters taken for comparison. A detailed comparative study is made on the proposed converter with few voltage lift converters in the literature, conventional boost with VM cell and quadratic boost converter. A 40 W prototype is constructed with 12 V input voltage and 96 V output voltage to verify the performance and validate the theoretical analysis of the proposed converter.

Three-port power converter for a solar charger

ABSTRACTA solar charger is proposed in this article. This solar charger, which is composed of a solar module and a three-port power converter, is used to charge a battery set with two batteries. Three ports of the three-port power converter are respectively connected to the solar module and two batteries. The three-port power converter integrates the power circuit for the interface for photovoltaic power generation and for voltage equalisation of the battery set. The operational mode for the three-port power converter varies depending on the voltage of the solar module. The current ripple and voltage stress of power semiconductor devices for the three-port power converter are less than those for a conventional boost power converter. A prototype is developed and tested to verify the performance of the proposed solar charger.

Selection methods of main circuit parameters for modular multilevel converters

The modular multilevel converter (MMC) will be used in power systems more and more widely. The main circuit parameter design of the MMC impacts the initial investment and the operating performance of the system. In this study the parameter design problem of several important elements in the main circuit of the MMC, such as the link transformer, the arm reactor, the sub-module (SM) capacitor and the SM power electronic devices are analysed. Based on the fundamental equivalent circuit of the MMC, the design method for the rated valve side no-load voltage of the link transformer is proposed; and the variation range of the rated valve side no-load voltage is determined as (1.00-1.05)/2 times of the DC side voltage. By introducing the concept of the equivalent capacity discharging time constant H , the nearly constant relationship between the fluctuation ratio of the SM capacitor voltage and the H -value for different projects is discovered, which means the H -value is independent of particular projects. In this study, the corresponding parameters of several practical projects are analysed and the recommended H -value is given as 40 ms. The voltage and current stress of the SM power electronic devices is investigated for the four extreme operating conditions by the analytical formulae of the MMC; and it is discovered that the current stress of the SM power electronic devices changes greatly with the operating condition. By introducing the concepts of the phase unit series resonance frequency and the circulating current resonance frequency, the principle for designing the parameter of the arm inductor is established. Through analysing the corresponding parameters of several real projects, the recommended value of the phase unit series resonance frequency is given as the rated frequency of the connected AC system.

Minimum Flying Capacitor for <italic>N</italic>-Level Capacitor DC/DC Boost Converter

This paper proposes a multilevel flying capacitor dc/dc boost converter (FCBC) with a small capacitance of the flying capacitor for the reduction of converter size. In this paper, the design methods for the boost inductor and the flying capacitor in the n -level FCBC are principally and experimentally confirmed. Furthermore, the boost inductor is designed based on maximum product of voltage-time, regardless the number of level. Meanwhile, the minimum capacitance of the flying capacitor is designed based on the maximum switching device voltage stress, regardless of the output voltage ripple influences. Moreover, the achieved maximum efficiency of the designed three-level FCBC is 98.5% at the output power of 1 kW. Finally, the effectiveness of small capacitances of the flying capacitor in the three-level and five-level FCBCs is analyzed. The characteristics of the distorted voltage across the input voltage source and the boost inductor, and the distorted current to the output side (output capacitor and load) are investigated with several capacitances of the flying capacitors in the three-level and five-level FCBCs. As a result, it is experimentally confirmed that the distorted voltage is drastically reduced by increasing the number of level. Besides, the distorted current is almost the same although the number of level is increased. Therefore, based on the experimental results, it is shown that small capacitance of the flying capacitor can be used in the n -level FCBC without compromising the stability of converter operation.

Design and Implementation of a Novel Multilevel DC–AC Inverter

In this paper, a novel multilevel dc–ac inverter is proposed. The proposed multilevel inverter generates seven-level ac output voltage with the appropriate gate signals’ design. Also, the low-pass filter is used to reduce the total harmonic distortion of the sinusoidal output voltage. The switching losses and the voltage stress of power devices can be reduced in the proposed multilevel inverter. The operating principles of the proposed inverter and the voltage balancing method of input capacitors are discussed. Finally, a laboratory prototype multilevel inverter with 400-V input voltage and output $220 {\text{V}}_{\text{rms}}/2\,{\text{kW}}$ is implemented. The multilevel inverter is controlled with sinusoidal pulse-width modulation (SPWM) by TMS320LF2407 digital signal processor (DSP). Experimental results show that the maximum efficiency is 96.9% and the full load efficiency is 94.6%.

A Single-Phase PV Quasi-Z-Source Inverter With Reduced Capacitance Using Modified Modulation and Double-Frequency Ripple Suppression Control

In single-phase photovoltaic (PV) system, there is double-frequency power mismatch existed between the dc input and ac output. The double-frequency ripple (DFR) energy needs to be buffered by passive network. Otherwise, the ripple energy will flow into the input side and adversely affect the PV energy harvest. In a conventional PV system, electrolytic capacitors are usually used for this purpose due to their high capacitance. However, electrolytic capacitors are considered to be one of the most failure prone components in a PV inverter. In this paper, a capacitance reduction control strategy is proposed to buffer the DFR energy in single-phase Z-source/quasi-Z-source inverter applications. Without using any extra hardware components, the proposed control strategy can significantly reduce the capacitance requirement and achieve low input voltage DFR. Consequently, highly reliable film capacitors can be used. The increased switching device voltage stress and power loss due to the proposed control strategy will also be discussed. A 1-kW quasi-Z-source PV inverter using gallium nitride (GaN) devices is built in the lab. Experimental results are provided to verify the effectiveness of the proposed method.

Prediction of a New Cascaded Hybrid Multilevel Inverter with Less Device Count

<p>Multilevel inverters have been opted for high power applications due to reduced harmonic distortion, less device voltage stress and modular structure. This work proposes new modified hybrid H-bridge multilevel inverter using auxiliary switch. This proposed inverter produces five levels output with five power devices and clamping diodes as a phase voltage and nine levels as a line voltage.The levels of the inverters are decided based on the phase voltage not on the line voltage. In this paper the performance of the proposed inverter are measured in terms of line voltage. However, by increase in the number of levels the proposed inverter with reduced number of switches produces low switching losses and improves the efficiency of the inverter. This method achieves the variation of Total Harmonic Distortion (THD) in the inverter and output voltage is observed for various modulation indices. Simulation is performed using MATLAB-SIMULINK for line to line output voltage. Variable Amplitude Phase Disposition (VAPD) strategy provides output with relatively low distortion for all the strategies. It is also seen that VAPOD is found to perform better for all strategies since it provides relatively higher fundamental RMS output voltage.</p>

Dual Switches DC/DC Converter With Three-Winding-Coupled Inductor and Charge Pump

In order to obtain a high step-up voltage gain, high-efficiency converter, this paper proposed a dual switches dc/dc converter with three-winding-coupled inductor and charge pump. The proposed converter composed of dual switches structure, three-winding-coupled inductor, and charge pump. This combination facilitates realization of high step-up voltage gain with a low voltage/current stress on the power switches. Meanwhile, the voltage across the diodes is low and the diode reverse-recovery problem is alleviated by the leakage inductance of the three-winding-coupled inductor. Taking all these into consideration, the efficiency can be high. This paper illustrated the operation principle of the proposed converter; discussed the effect of leakage inductance on voltage gain; the conditions of zero current shutting off of the diodes are illustrated; the voltage and current stress of the power devices are shown; a comparison between the performance of the proposed converter and previous high step-up converters was conducted. Finally, a prototype rated at 500 W has been established, and the experimental results verify the correctness of the analysis.

High step‐up isolated resonant converter with voltage quadrupler rectifier and dual‐phase‐shift control

An isolated resonant converter with voltage-quadrupler rectifier (VQR) and dual-phase-shift (DPS) control strategy is proposed for high step-up and wide voltage range applications. The VQR is composed of a resonant-type voltage doubler and a conventional voltage doubler. The output voltage is improved and the voltage stresses of the secondary-side devices are reduced significantly. Hence, low voltage-rated switches and diodes with better switching and conduction performances can be applied to improve the efficiency. The DPS modulation strategy is adopted to implement the boost and buck modes operation, and to achieve wide voltage gain range. With the DPS control strategy, zero-voltage switching performance is achieved for both the primary and secondary sides power devices, and zero-current switching is achieved for all of the diodes within the entire voltage and load ranges. The operational principles and characteristics of the proposed converter are presented in detail. The analysis and performance have been fully validated experimentally on a 400 V/400 W output hardware prototype.

Efficient bridgeless PFC converter with reduced voltage stress

SummaryAn efficient bridgeless power factor correction converter with reduced voltage stress is proposed. In the proposed converter, the input full‐bridge rectifier is removed to reduce the conduction loss of rectification, and the voltage stress of switching devices is significantly reduced by utilizing the additional circuit composed of a capacitor and a diode. Therefore, low‐voltage‐rating diodes with less forward voltage drop and low‐voltage‐rating Metal‐Oxide‐Semiconductor Field‐Effect Transistor (MOSFET) with low RDS(on) is utilized. The proposed converter is based on the single‐ended primary‐inductor converter power factor correction operation in discontinuous conduction mode to achieve a high power factor with a simple control circuit. Consequently, the proposed converter can provide a high power factor and a high power efficiency, and it is also suitable for low‐cost converter for high input/output voltage system. The operational principles, steady‐state analysis, and design equations of the proposed converter are described in detail. Experimental results are verified for a 130 W prototype at a constant switching frequency 100 kHz. Copyright © 2015 John Wiley & Sons, Ltd.

A Step-up Resonant Converter for Grid-Connected Renewable Energy Sources

With the rapid development of large-scale renewable energy sources and HVDC grid, it is a promising option to connect the renewable energy sources to the HVDC grid with a pure dc system, in which high-power high-voltage step-up dc–dc converters are the key equipment to transmit the electrical energy. This paper proposes a resonant converter which is suitable for grid-connected renewable energy sources. The converter can achieve high voltage gain using an LC parallel resonant tank. It is characterized by zero-voltage-switching (ZVS) turn-on and nearly ZVS turn-off of main switches as well as zero-current-switching turn-off of rectifier diodes; moreover, the equivalent voltage stress of the semiconductor devices is lower than other resonant step-up converters. The operation principle of the converter and its resonant parameter selection is presented in this paper. The operation principle of the proposed converter has been successfully verified by simulation and experimental results.

Prolog to, "High-power wind energy conversion systems: State-of-the-art and emerging technologies"

This paper reviews state-of-the-art progress with respect to MW wind generator-converter configurations, wind farm configurations and grid code compliance methods. Four categories of generator-converter configurations have been identified and analyzed based on component count, modularity, reliability, converter/control complexity, device voltage stress, operation voltage, and achievable power levels.

A Novel Soft Switching Based Fuzzy Logic Control for Single Phase Inverter

—This The Pulse Width Modulation (PWM) DC-to-AC inverter has been widely used in many applications due to its circuit simplicity and rugged control scheme. It is however driven by a hard-switching pulse width modulation (PWM) inverter, which has low switching frequency, high switching loss, high electro-magnetic interference (EMI), high acoustic noise and low efficiency, etc. To solve these problems of the hard-switching inverter, many soft-switching inverters have been designed in the past. Unfortunately, high device voltage stress, large dc link voltage ripples, complex control scheme and so on are noticed in the existing soft-switching inverters. This proposed work overcomes the above problems with simple circuit topology and all switches work in zero-voltage switching condition. Comparative analysis between conventional open loop, PI and fuzzy logic based soft switching inverter is also presented and discussed. Keywords—Zero voltage switching, Inverter, Dc link, PI controller, Fuzzy logic system control ,Modulation strategy, Soft switching

Understanding the Effect of PCB Layout on Circuit Performance in a High-Frequency Gallium-Nitride-Based Point of Load Converter

The introduction of enhancement-mode gallium-nitride-based power devices such as the eGaN FET offers the potential to achieve higher efficiencies and higher switching frequencies than possible with silicon MOSFETs. With the improvements in switching performance and low parasitic packaging provided by eGaN FETs, the printed circuit board (PCB) layout becomes critical to converter performance. This paper will study the effect of PCB layout parasitic inductance on efficiency and peak device voltage stress for an eGaN FET-based point of load (POL) converter operating at a switching frequency of 1 MHz, an input voltage range of 12-28 V, an output voltage of 1.2 V, and an output current up to 20 A. This paper will also compare the parasitic inductances of conventional PCB layouts and propose an improved PCB design, providing a 40% decrease in parasitic inductance over the best conventional PCB design.

An Extended Switched-inductor Quasi-Z-source Inverter

In this paper, an extended switched-inductor quasi-Z-source inverter (ESL-qZSI) with high boost voltage inversion ability is presented, which combines the SL-qZSI with the traditional boost converter, as well as improves the switched-inductor cell. Compared with the classic qZSI topologies, the proposed topology reduces the voltage stresses of capacitors, power devices and diodes for the same input and output voltage. Furthermore, the conversion efficiency is improved. The operation principle of the proposed topology is analyzed in details, which is followed by the comparison between the three topologies. In addition, the performance of the proposed topology is verified by simulations and experiments.