Converter Using SiC‐MOSFET for Ultra‐High‐Speed Elevator

In this study, we developed a converter based on SiC (Silicon Carbide)‐MOSFET for use in ultra‐high‐speed elevators, with a reduced volume of 15% compared with the conventional converter. We succeeded in reducing the power loss of the converter unit by 56% compared to the conventional converter in one round trip under high temperature condition. Recently, because of their useful characteristics, wide‐gap semiconductors, such as SiC and GaN, have gained considerable attention for use in various applications in the power electronics systems. Therefore, we studied the use of a converter in elevator systems based on SiC‐MOSFET. We used a 1200 V/800 A SiC‐MOSFET module for the converter unit. We developed a prototype of the converter unit and the control panel by applying for the SiC‐MOSFET module for an ultra‐high‐speed elevator. As a result, the setting area of the control panel (main part) becomes less than 43% of the conventional panel. We tried to demonstrate the working of a 68‐kW elevator by applying the prototype control panel. Because of the characteristic of the switching loss of SiC‐MOSFET, the power loss of the converter unit has almost no dependence on temperature. An energy‐saving effect of approximately 17% was achieved in the total elevator system in one round trip under high‐temperature condition.     

A bidirectional isolated DC/DC converter as a core circuit for 3.3‐kV/6.6‐kV power conversion systems in the next generation

This paper describes a bidirectional isolated DC/DC converter considered as a core circuit for next‐generation 3.3‐kV/6.6‐kV high‐power‐density power conversion systems. The DC/DC converter is intended to use power switching devices based on SiC and/or GaN, which will be available on the market in the near future. A 350‐V, 10‐kW, and 20‐kHz DC/DC converter is designed, constructed, and tested in this paper. It consists of two single‐phase full‐bridge converters with the latest trench‐gate Si‐IGBTs and a 20‐kHz transformer with a nano‐crystalline soft‐magnetic material core and litz wires. The transformer plays an essential role in achieving galvanic isolation between the two full‐bridge converters. The overall efficiency from the DC‐input to DC‐output terminals is accurately measured to be as high as 97%, excluding gate drive circuit and control circuit losses from the whole loss. Moreover, loss analysis is carried out to estimate effectiveness in using SiC‐based power switching devices. The loss analysis clarifies that the use of SiC‐based power devices may bring a significant reduction in conducting and switching losses to the DC/DC converter. As a result, the overall efficiency may reach 99% or higher. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 163(2): 75–83, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20505     

Efficient bridgeless PFC converter with reduced voltage stress

An 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 R_DS(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.     

Operation analysis of quasi‐resonant,high‐frequency transformer link dc–ac converters applied to phase‐shift PWM control on the secondary side

In recent years, the soft‐switching techniques have attracted attention for their peculiar advantages such as low switching loss, high power density, EMI/RFI noise reduction, and so on. The authors have previously reported on a quasi‐resonant dc–dc converter using new phase‐shift PWM control scheme. By using the proposed control scheme, circulating current is eliminated and ZVS (Zero Voltage Switching) is achieved with small commutating current. As a result, the conduction losses caused by their currents are substantially reduced. In this paper, the authors apply a proposed control scheme to a quasi‐resonant high‐frequency transformer link dc–ac converter. As a result, all switching devises in this dc–ac converter can achieve soft switching with small commutating current irrespective of inverter mode and rectifier mode. Its operating principle and unique features are described as compared with the symmetrical control scheme of dc–ac converter. Operating performance of this dc–ac converter in the steady state is illustrated by means of simulation results. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 88–98, 2000     

A power decoupling control method for an isolated single‐phase AC‐to‐DC converter based on a high‐frequency cycloconverter

This paper proposes a new power decoupling method for a high‐frequency cycloconverter which converts the single‐phase line‐frequency ac input to the high‐frequency ac output directly. The cycloconverter consists of two half‐bridge inverters, two input filter capacitors, and a series‐resonant circuit. The proposed power decoupling method stores the input power ripple at double the line frequency in the filter capacitors. Therefore, the proposed method achieves a unity power factor in ac input and a constant current amplitude in the high‐frequency output without any additional switching device or energy storage element. This paper theoretically discusses the principle and operating performance of the proposed power decoupling method, and the viability is confirmed by using an experimental isolated ac‐to‐dc converter based on the high‐frequency cycloconverter. As a result, the proposed power decoupling method effectively improved the displacement power factor in the line current to more than 0.99 and reduced the output voltage ripple to 4% without any electrolytic capacitor.     

A Five‐Element Multiplex Resonant Full‐Bridge DC‐DC Converter with a Variable Inductive Reactance

A five‐element multiplex resonant (LLCLC) full‐bridge DC‐DC converter controlled by pulse frequency modulation (PFM) is proposed in this paper. The high frequency (HF)‐link resonant DC‐DC converter proposed herein can perform wide‐range output power and voltage regulation with a narrow frequency range due to an antiresonant tank that works effectively as a wide‐range variable inductor. The advantageous characteristics of the antiresonant tank provide overcurrent protection in the case of the short‐circuited load condition as well as in the startup interval. Thus, the technical challenges of a conventional LLC DC‐DC converter can be overcome, and the reliability of the relevant switch‐mode power supplies can be improved. The operating principle of the LLCLC DC‐DC converter is described, after which its performance is evaluated in an experimental setup based on the 2.5 kW prototype. Finally, the feasibility of the proposed DC‐DC converter is discussed from a practical point of view.     

Si IGBT/SiC MOSFET混合器件及其应用研究

综述了Si IGBT/SiC MOSFET混合器件在门极优化控制策略、集成驱动设计、热电耦合损耗模型、芯片尺寸配比优化和混合功率模块研制等方面的最新研究成果与进展。Si IGBT/SiC MOSFET混合器件结合了SiC MOSFET的高开关频率、低开关损耗特性和Si IGBT的大载流能力和低成本优势,已有文献的最新研究和实验结果验证了该类器件的优异特性,表明其对高性能电力电子器件实现更高电流容量、更高开关频率和较低成本具有重要意义,是高性能变换器应用中非常有潜力的功率器件类型。     

Series resonant ZCS‐PFM DC‐DC power converter with high‐frequency high‐voltage transformer link for high‐power magnetron drive

This paper presents a single lossless inductive snubber‐assisted ZCS‐PFM series resonant DC‐DC power converter with a high‐frequency high‐voltage transformer link for industrial‐use high‐power magnetron drive. The current flowing through the active power switches rises gradually at a turned‐on transient state with the aid of a single lossless snubber inductor, and ZCS turn‐on commutation based on overlapping current can be achieved via the wide range pulse frequency modulation control scheme. The high‐frequency high‐voltage transformer primary side resonant current always becomes continuous operation mode, by electromagnetic loose coupling design of the high‐frequency high‐voltage transformer and the magnetizing inductance of the high‐frequency high‐voltage transformer. As a result, this high‐voltage power converter circuit for the magnetron can achieve a complete zero current soft switching under the condition of broad width gate voltage signals. Furthermore, this high‐voltage DC‐DC power converter circuit can regulate the output power from zero to full over audible frequency range via the two resonant frequency circuit design. Its operating performances are evaluated and discussed on the basis of the power loss analysis simulation and the experimental results from a practical point of view. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 153(3): 79–87, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20126     

Single‐stage single‐switch PFC converter for wide‐input extreme step‐down voltage applications

This paper presents a new single‐stage single‐switch high power factor correction AC/DC converter suitable for low‐power applications (< 150 W) with a universal input voltage range (90–265 V_rms). The proposed topology integrates a buck–boost input current shaper followed by a buck and a buck–boost converter, respectively. As a result, the proposed converter can operate with larger duty cycles compared with the existing single‐stage single‐switch topologies, hence, making them suitable for extreme step‐down voltage conversion applications. Several desirable features are gained when the three integrated converter cells operate in discontinuous conduction mode. These features include low semiconductor voltage stress, zero‐current switch at turn‐on, and simple control with a fast well‐regulated output voltage. A detailed circuit analysis is performed to derive the design equations. The theoretical analysis and effectiveness of the proposed approach are confirmed by experimental results obtained from a 100‐W/24‐V_dc laboratory prototype. Copyright © 2011 John Wiley & Sons, Ltd.     

Iron Loss Characteristics of Electrical Steel Sheet under Inverter Excitation by Power Semiconductor with Extremely Low On‐Voltage Property

In this study, it is demonstrated that the iron loss from the SiC‐MOSFET, which represents a new power semiconductor with an extremely low on‐voltage for electric machine drives, is almost the same as that from an Si‐IGBT, which is a conventional power semiconductor. In order to evaluate the iron loss characteristics when an SiC device is used, two single‐phase pulse width modulation inverters were built and used for the excitation of a ring made up of electrical steel sheet. One of the inverter employed an SiC‐MOSFET, and the other inverter employed an Si‐IGBT. The iron losses for the two inverters are compared.     

A single‐stage LED streetlight driver with PFC and digital PWM dimming capability

This paper proposes a single‐stage light‐emitting diode (LED) driver that offers power‐factor correction and digital pulse–width modulation (PWM) dimming capability for streetlight applications. The presented LED streetlight driver integrates an alternating current–direct current (AC–DC) converter with coupled inductors and a half‐bridge‐type LLC DC–DC resonant converter into a single‐stage circuit topology. The sub‐circuit of the AC–DC converter with coupled inductors is designed to be operated in discontinuous‐conduction mode for achieving input‐current shaping. Zero‐voltage switching of two active power switches and zero‐current switching of two output‐rectifier diodes in the presented LED driver decrease the switching losses; thus, the circuit efficiency is increased. A prototype driver for powering a 144‐W‐rated LED streetlight module with input utility‐line voltages ranging from 100 to 120 V is implemented and tested. The proposed streetlight driver features cost‐effectiveness, high circuit efficiency, high power factor, low levels of input‐current harmonics, and a digital PWM dimming capability ranging from 20% to 100% output rated LED power, which is fulfilled by a micro‐controller. Satisfying experimental results, including dimming tests, verify the feasibility of the proposed LED streetlight driver. Copyright © 2016 John Wiley & Sons, Ltd.     

A novel modulation technique with interleaved‐and‐shifted shoot‐through state placement for quasi‐Z‐source inverters

In this paper, a single‐phase quasi‐Z‐source (qZS) inverter (qZSI), integrating the pulse width modulation (PWM) control with interleaved‐and‐shifted shoot‐through state (STS) placement modulation technique, is proposed to simultaneously achieve both dc voltage boost and dc‐ac inversion. Instead of placing the STS in both inverter legs simultaneously, the addressed method inserts the STS only in left/right inverter leg separately during the positive/negative half cycle of the output voltage to reduce switching losses and thermal stresses of the power devices. The STS shift is also studied to decrease the switching numbers of power devices and thus can improve the efficiency further. Theoretical analysis and design guidelines of the studied inverter are included. Improvement in effectiveness and performance of the devised scheme and modulation strategy are proved experimentally and compared with the previous studies on a built laboratory prototype.     

A novel single‐stage AC–DC converter with quasi‐resonant zero‐voltage‐switching for high power factor and high efficient applications

A new single‐stage‐isolated ac–dc converter that can guarantee both high efficiency and high power factor is proposed. It is based on a new dc–dc topology that has prominent conversion ratio similar to that of boost topology so that it is adequate to deal with the universal ac input. In addition, since it utilizes the transformer more than others based on the general flyback topology, the size of whole power system can be reduced due to the reduced transformer. Moreover, the voltage stresses on the secondary rectifiers can be clamped to the output voltage by adopting the capacitive output filter and clamp diode, and the turn‐off loss in the main switch can be reduced by utilizing the resonance. Furthermore, since this converter operates at the boundary conduction mode, the line input current can be shaped as the waveform of a line voltage automatically and the quasi‐resonant zero‐voltage switching can be obtained. Consequently, it features higher efficiency, lower voltage stress, and smaller sized transformer than other topologies. A 100 W prototype has been built and tested as the validation of the proposed topology. Copyright © 2010 John Wiley & Sons, Ltd.     

Isolated Ac/Dc Converter Using Soft Switching Technique

This paper presents a high‐frequency isolated ac/dc converter using the soft switching technique. The ac/dc converter consists of a matrix converter for transforming three‐phase ac voltage to high‐frequency ac voltage, a high‐frequency transformer, and an ac/dc rectifier. In order to reduce the switching loss, soft switching at every commutation of the matrix converter and ac/dc converter is achieved. The effectiveness of the proposed converter and the control scheme was verified by experiments.     

Development of High‐Power Density Interleaved dc/dc Converter with SiC Devices

We developed an interleaved dc/dc converter with SiC devices. We applied full‐SiC modules including MOSFETs and SBDs to the interleaved dc/dc converter to achieve a high‐power density. An SiC has a high temperature resistance, which facilitates an improvement in high‐frequency drives. We achieved a high‐power density by utilizing this high temperature resistance. We also fabricated a prototype and tested it with loads up to 65 kW.     

Analysis and implementation of a high‐efficiency zero‐voltage‐zero‐current‐switching DC–DC converter

A high‐efficiency zero‐voltage‐zero‐current‐switching DC–DC converter with ripple‐free input current is presented. In the presented converter, the ripple‐free boost cell provides ripple‐free input current and zero‐voltage switching of power switches. The resonant flyback cell provides zero‐voltage switching of power switches and zero‐current switching of the output diode. Also, it has a simple output stage. The proposed converter achieves high efficiency because of the reduction of the switching losses of the power switches and the output diode. Detailed analysis and design of the proposed converter are carried out. A prototype of the proposed converter is developed and its experimental results are presented for validation. Copyright © 2011 John Wiley & Sons, Ltd.     

基于低压器件的高效高功率密度串联谐振DC-DC变换器

工作于MHz的串联谐振变换器SRC(series resonant converter)由于简单的结构与全负载范围的原边开关管软开关,可以实现较高的效率与功率密度,适合隔离型DC-DC变换器高频、模块化的发展趋势,因此越来越受工业界与学术界的关注.业界基于高压Si MOSFET的DC-DC模块大多工作在数百kHz,其效...     

The Proposal of Isolated Single‐Stage AC‐DC Converter

An isolated ac‐dc converter has been used in various applications, such as power supply and as a battery charger for electric vehicle. In conventional converters, a loss in each conversion stage can be reduced by applying a soft switching method. However, a conventional converter has many conversion stages including the rectifier stage, power factor correction, and dc/dc converter stages; thus, it is difficult to reduce the total converter loss and size. In this paper, we propose a novel isolated‐type ac‐dc converter with only one conversion stage; it can realize a zero‐voltage switching operation in all switching devices.     

Performance Verification of High‐Efficiency PV Power Conditioner Integrated with SiC MOSFETs and Cooperative Control Method

A high conversion efficiency is always required for photovoltaic power conditioners to utilize PV‐generated DC power with minimal loss. The cooperative control method has been developed as one of the control methods that improves the conversion efficiency, which is applicable to nonisolated power conditioners consisting of a boost converter and an inverter. In the cooperative control method, the boost converter creates part of the AC voltage waveform, and either the boost converter or inverter performs switching only during a required period. Therefore, it has the advantage of reducing switching losses. In this paper, we present a study of a cooperative‐control‐type power conditioner assuming its use in grid‐connected operation and the results of a performance verification of prototype power conditioner. A microcontroller is used for cooperative control. The experimental results show that the prototype power conditioner integrated with SiC MOSFETs and the cooperative control method achieves an efficiency of 97.4% at an output of 5.5 kW.     

A High‐Frequency Cycloconverter Based on a Phase‐Shift Control Method

This paper proposes a new control method for a high‐frequency cycloconverter consisting of two half‐bridge inverters and a series–resonant circuit. This cycloconverter acts as an ac‐to‐ac direct power conversion circuit without any dc stage. This circuit does not require a diode bridge rectifier, and thus, can be used to reduce forward voltage drops and power losses in the diodes. A new phase‐shift control method is proposed to regulate the capacitor voltage in each half‐bridge inverter and to achieve zero‐voltage switching. The proposed phase‐shift control is theoretically discussed and is also verified by an experimental circuit consisting of superjunction power MOSFETs. As a result, the proposed high‐frequency cycloconverter exhibits a good power conversion efficiency as high as 97.7% at the rated power of 1.3 kW.