VVVF on-line control of matrix converters

A matrix converter does not have any energy storage components, so it is smaller than a converter-inverter system with same KVA. Although a matrix converter requires 18 switching devices instead of 12, each device capacity is 0.383 times with a total capacity of 0.575 times that of the converter-inverter system. For the matrix converter, we proposed a firing sequence which eliminated voltage and current spikes in switching operations and a control method I which generated the output voltage of 0.866 times the supply voltage. Moreover, we proposed control method II which improved the waveform distortion of the input current and realized unity input power factor. In this paper, we propose a new VVVF gate circuit based on control method II for matrix converter, which can on-line control input current waveform and output voltage waveform to sinusoidal even if there is fluctuation, asymmetry, and/or harmonics in the supply voltage. We also confirm by experiments that the waveform distortion of the input current and the input power factor were greatly improved. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 119(2): 81–90, 1997     

A high‐voltage gain nonisolated noncoupled inductor based multi‐input DC‐DC topology with reduced number of components for renewable energy systems

This paper proposes a modular nonisolated noncoupled inductor‐based high‐voltage gain multi‐input DC‐DC converter. Despite the high‐voltage gain of the proposed topology, the average of normalized voltage stress (NVS) on its switches/diodes is low. This property leads to less loss and cost of switches/diodes. Using the same number of components, the proposed topology produces higher voltage gains, in comparison with recently presented high step‐up topologies. Also, the proposed topology utilizes less number of components (capacitors, inductors, diodes, and switches) for producing a desired voltage gain, which can reduce the size, mass, cost, complexity, and losses and improve the efficiency of converter. Continuous current of input sources is another main advantage of the proposed topology. All the abovementioned characteristics have made the proposed topology very suitable for renewable energy systems (or even hybrid/electric vehicles). Design considerations of the proposed topology have also been presented. For better evaluation, the proposed topology has been compared with some of recently presented high step‐up structures, from viewpoints of producible voltage gain, number of components, and normalized voltage stress (NVS) on switches/diodes. Finally, the prototype of 2‐input version has been experimentally implemented. Obtained experimental results confirm appropriate performance of the proposed topology.     

一种提高矩阵变换器电压增益的空间矢量调制法

与传统的电压源型逆变器相比,矩阵变换器主要的缺点之一是在输入及输出电流为正弦时,输出输入电压传输比限制在0.866。为克服此缺点,在传统的矩阵变换器空间矢量调制方法的基础上,提出了一种提高电压增益的调制策略,进行了详细说明,概念清楚、控制简单,不需要复杂的数学计算。此调制策略没有使用零矢量,较传统方法换流数量减少,输出输入电压传输比提高到0.95以上,但输出电压及输入电流波形出现了一定程度的畸变。通过仿真证实了理论分析,也显示了此调制策略的优缺点。     

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.     

A new interleaved bidirectional dc/dc converter with zero voltage switching and high voltage gain: analyses,design and simulation

In this paper, a new interleaved non‐isolated bidirectional dc–dc converter with capability of zero voltage switching and high voltage gain is proposed. In the proposed converter by using two coupled inductors and one capacitor, the voltage gain is extended. Moreover, by using only an auxiliary circuit that includes an inductor and two capacitors, the zero voltage switching (ZVS) of two used switches in the first phase of converter can be achieved. The ZVS operation of two used switches in the second phase is always obtained without using any extra auxiliary circuit. This converter similar to other interleaved converters has low input current ripple and low current stress on switches. In this paper, the proposed converter is analyzed in all operating modes, and also the voltage gain, required conditions for ZVS operation of switches, voltage and current stresses of all switches, and the value of input current ripple in both boost and buck operations are obtained. Finally, the accuracy performance of the proposed converter is verified through simulation results in EMTDC/PSCAD software. Copyright © 2017 John Wiley & Sons, Ltd.     

一种带LCL滤波器的新型矩阵变换器控制策略

矩阵变换器由于输出电压、电流中存在的谐波成分对所带的负载有很大影响,引入电压、电流双闭环控制策略,提出一种带LCL滤波器的新型矩阵变换器.该变换器包含交-直(整流)和直-交(逆变)2级电路,其直流侧不需要储能元件,整流级和逆变级采用双向开关,在一定的约束条件下可降低开关的数量.分析了矩阵变换器的拓扑结构、双空间矢量调控算法、LCL滤波器设计及其在矩阵变换器逆变级的应用等.通过Matlab/Simulink软件进行了仿真实验,结果表明,带LCL滤波器的新型矩阵变换器能有效地降低输出电压、电流谐波,并能抑制输入侧谐波对输出电压、电流的影响.     

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 new parallel ZVS converter with less power switches and low current stress components

A new direct current (DC)/DC converter with parallel circuits is presented for medium voltage and power applications. There are five pulse‐width modulation circuits in the proposed converter to reduce current stress at low voltage side for high output current applications. These five circuits share the same power switches in order to reduce switch counts. To reduce the converter size, conduction loss, and voltage stress of power semiconductors, the series connections of power metal‐oxide‐semiconductor field‐effect transistor (MOSFET) with high switching frequency instead of insulated gate bipolar transistor (IGBT) with low switching frequency are adopted. Thus, the voltage stress of MOSFETs is clamped at half of input voltage. The switched capacitor circuit is adopted to balance input split capacitor voltages. Asymmetric pulse‐width modulation scheme is adopted to generate the necessary switching signals of MOSFETs and regulate output voltage. Based on the resonant behavior at the transition interval of power switches, all MOSFETs are turned on under zero voltage switching from 50% load to 100% load. The circuit configuration, operation principle, converter performance, and design example are discussed in detail. Finally, experimental verifications with a 1.92 kW prototype are provided to verify the performance of the proposed converter. Copyright © 2015 John Wiley & Sons, Ltd.     

A control method to realize sinusoidal input and output current waveforms for matrix converters based on PWM

A matrix converter (MC) is a three‐phase AC‐to‐AC direct converter without any energy storage requirement. It is expected to be a next‐generation converter by reason of possibilities of small size and high efficiency. At present, there are some problems preventing it from being used practically. One of the problems is the distortion in the input current. The control methods proposed so far have not realized sufficient reduction of the input current harmonics compared with conventional PWM rectifiers. As a solution to these problems, many approaches have been proposed. In the present paper, an improved PWM method that can achieve both sinusoidal input and output currents simultaneously is considered. In this method, the MC is treated as a controlled voltage source viewed from the load side. On the other hand, it is treated as a controlled current source viewed from the line side. The proposed control method is based on the mathematical expression of the function of the PWM operation of MC. To improve the input current waveform, two line‐to‐line voltages of the three‐phase line are used to control the output current. The output duty ratio of the two line‐to‐line voltages is utilized to improve the input current waveform without affecting the controllability of the output current. In addition, the compensation of the variations in the line voltage and the output current are introduced. In this way, the proposed method can realize the sinusoidal input and output currents. The effectiveness of the proposed control method is confirmed by some experimental results employing a laboratory prototype. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(1): 66–76, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20242     

A soft‐switching high step‐up DC‐DC converter with a single magnetic component

A soft‐switching high step‐up DC‐DC converter with a single magnetic component is presented in this paper. The proposed converter can provide high voltage gain with a relatively low turn ratio of a transformer. Voltage doubler structure is selected for the output stage. Due to this structure, the voltage gain can be increased, and the voltage stresses of output diodes are clamped as the output voltage. Moreover, the output diode currents are controlled by a leakage inductance of a transformer, and the reverse‐recovery loss of the output diodes is significantly reduced. Two power switches in the proposed converter can operate with soft‐switching due to the reflected secondary current. The voltages across the power switches are confined to the clamping capacitor voltage. Steady‐state analysis, simulation, and experimental results for the proposed converter are presented to validate the feasibility and the performance of the proposed converter. Copyright © 2012 John Wiley & Sons, Ltd.     

A novel three‐phase converter using a three‐phase series chopper

This paper proposes a novel three‐phase converter using a three‐phase series chopper. The proposed circuit is composed of three switching devices, three‐phase diode bridge, input reactors, and LC low‐pass filter. In the conventional circuit, which combines three‐phase diode bridge and boost voltage chopper, to obtain sinusoidal input current the output voltage must be two or three times larger than the maximum input line voltage. However, in the proposed circuit, the input current can be controlled to be sinusoidal also when the output voltage is the same as the maximum input line voltage. This can be achieved because in the proposed circuit the discharging current of the reactors does not flow through the voltage source. The control method of the proposed circuit is as simple as that of the conventional circuit since all three switching devices are simultaneously turned on and off. This paper discusses the theoretical analysis and the design of the proposed circuit. In addition, simulation and experimental results are reported. The proposed circuit has obtained a 93% efficiency, and 99.7% at 1.3kW load as the input power factor. © 2000 Scripta Technica, Electr Eng Jpn, 132(4): 79–88, 2000     

Common mode voltage reduction of quasi‐Z source indirect matrix converter

Quasi‐Z source indirect matrix converter (IMC) combines both advantages of conventional IMC and quasi‐Z source inverter, for example, no direct current (DC) link capacitor, compact all‐silicon power converter, bidirectional power flow, input power factor controllable, and high voltage gain; moreover, it does not require additional input filter, because continuous quasi‐Z source network integrates LC filter function. However, there is no literature to disclose common mode voltage (CMV) issue of quasi‐Z source IMC. In this paper, for the first time, the CMV issue and reduction of quasi‐Z source IMC are investigated. Firstly, the CMV of quasi‐Z source IMC is analyzed when using current typical modulation method, which follows the brief introduction of topology and modulation method for quasi‐Z source IMC, and the factors that affect the CMV are figured out; Secondly, referring to the CMV reduction methods of conventional IMC, two solutions named as Methods I and II to reduce the CMV for quasi‐Z source IMC are developed, which are achieved in the inverter stage; the third CMV reduction method is proposed in the rectifier stage through redefining the six sectors of the rectifier stage, which can implement zero current commutation. Experimental bench is built to test three approaches for reducing the CMV of quasi‐Z source IMC. Comparative evaluation is carried out between three methods and conventional modulation method. Experimental results verify that three methods can significantly reduce the CMV of quasi‐Z source IMC, with the CMV peak value reduction of 42%, but they present different features in terms of input and output current THDs, switching loss, CMV root mean square (RMS) value, modulation index limitation, and so on. Copyright © 2015 John Wiley & Sons, Ltd.     

矩阵变换器在非对称输入电压情况下的一种改进控制法

在非对称输入电压情况下，短阵变换器基于空间矢量控制法的输出电压和输入电流中都将含有谐波分量。通过采用时变调制比的方法，可以消除不对称输入电压的影响，从而获得对称正弦输出电压或输入电流。     

A single‐stage high power‐factor bridgeless AC‐LED driver for lighting applications

An alternating‐current light‐emitting diode (AC‐LED) driver is implemented between the grid and lamp to eliminate the disadvantages of a directly grid‐tied AC‐LED lamp. In order to highlight the benefits of AC‐LED technology, a single‐stage converter with few components is adopted. A high power‐factor single‐stage bridgeless AC/AC converter is proposed with higher efficiency, greater power factor, less harmonics to pass IEC 61000‐3‐2 class C, and better regulation of output current. The brightness and flicker frequency issues caused by a low‐frequency sinusoidal input are surpassed by the implementation of a high‐frequency square‐wave output current. In addition, the characteristics of the proposed circuit are discussed and analyzed in order to design the AC‐LED driver. Finally, some simulation and experimental results are shown to verify this proposed scheme. Copyright © 2012 John Wiley & Sons, Ltd.     

Extend output voltage range of AC/AC converters using a reversible indirect matrix converter

This paper proposes a reversible indirect matrix converter that expands the output voltage range. The proposed circuit has two operation modes. A buck mode that supplies an output voltage lower than the input voltage, and a boost mode that supplies an output voltage higher than the input voltage. In the boost mode, the proposed circuit has the characteristics of the current type inverter therefore, it is possible to obtain an output voltage with less harmonics. The proposed system is validated with a 2 kW prototype. The proposed circuit shows that the input/output voltage ratio of AC/AC direct conversion obtained is 0 to 1.2 or more. Moreover, the conversion efficiency of the proposed circuit is 92.8%.     

A novel quasi‐Z‐source indirect matrix converter

A new type of three‐phase quasi‐Z‐source indirect matrix converter (QZS‐IMC) is proposed in this paper. It uses a unique impedance network for achieving voltage‐boost capability and making the input current in continuous conduction mode (CCM) to eliminate the input filter. The complete modulation strategy is proposed to operate the QZS‐IMC. Meanwhile, a closed‐loop DC‐link peak voltage control strategy is proposed, and the DC‐link peak voltage is estimated by measuring both the input and capacitor voltages. With this proposed technique, a high‐performance output voltage control can be achieved with an excellent transient performance even if there are input voltage and load current variations. The controller is designed by using the small‐signal model. Vector control scheme of the induction motor is combined with the QZS‐IMC to achieve the motor drive. A QZS‐IMC prototype is built in laboratory, and experimental results verify the operating principle and theoretical analysis of the proposed converter. The simulation tests of QZS‐IMC based inductor motor drive are carried out to validate the proposed converter's application in motor drive. Copyright © 2013 John Wiley & Sons, Ltd.     

A new non‐isolated free ripple input current bidirectional DC‐DC converter with capability of zero voltage switching

In this paper, a new nonisolated free ripple input current bidirectional dc‐dc converter with capability of zero voltage switching (ZVS) is proposed. The free ripple input current condition at low voltage side is achieved by using third winding of a coupled inductor and a capacitor for the whole range of duty cycles. In the proposed structure, the voltage conversion ratio can be more increased by adding the turn ratio of the second winding of the coupled inductor for the whole range of duty cycles. By adjusting the value of an auxiliary inductor in the topology of the converter, according to the power, the ZVS operation of the implemented 2 switches can be achieved throughout the whole power range. The mentioned features of proposed converter are validated theoretically for both boost and buck operations. In this paper, the proposed converter is analyzed for all operating modes. Moreover, all equations of the voltages and currents of all components, voltage conversion ratio, the required conditions for ZVS operation of switches, and also required conditions for canceling input current ripple at low voltage side are obtained. Finally, the performance of the proposed converter is reconfirmed through experimental and EMTDC/PSCAD simulation results.     

全桥三电平变换器的一种新型控制策略

对全桥三电平变换器提出了一种新的脉宽调制控制策略一双移相（Double phase—shift,DPS）控制。对比斩波加移相（Chopping plus phase—shift,CPS）控制,该控制策略大大减小开关管体二极管的损耗,使全桥三电平变换器可以工作在三电平模式和两电平模式,从而提高了变换器的效率。同时保持开关管的电压应力只有输入电压的一半,使该变换器非常适合高压输入的场合,并实现所有开关管的零电压开关。此外,全桥三电平变换器输出滤波电感比传统全桥变换器也大为减小。副边整流二极管的电压应力得到了降低。由于变换器的输入电流纹波很小,输入滤波器也得到了减小。本文详细分析全桥三电平变换器在双移相控制策略下的工作原理,讨论参数设计,并且给出实验结果。     

Hybrid DC–DC converter with high efficiency,wide ZVS range,and less output inductance

In this paper, a new soft switching direct current (DC)–DC converter with low circulating current, wide zero voltage switching range, and reduced output inductor is presented for electric vehicle or plug‐in hybrid electric vehicle battery charger application. The proposed high‐frequency link DC–DC converter includes two resonant circuits and one full‐bridge phase‐shift pulse‐width modulation circuit with shared power switches in leading and lagging legs. Series resonant converters are operated at fixed switching frequency to extend the zero voltage switching range of power switches. Passive snubber circuit using one clamp capacitor and two rectifier diodes at the secondary side is adopted to reduce the primary current of full‐bridge converter to zero during the freewheeling interval. Hence, the circulating current on the primary side is eliminated in the proposed converter. In the same time, the voltage across the output inductor is also decreased so that the output inductance can be reduced compared with the output inductance in conventional full‐bridge converter. Finally, experiments are presented for a 1.33‐kW prototype circuit converting 380 V input to an output voltage of 300–420 V/3.5 A for battery charger applications. Copyright © 2015 John Wiley & Sons, Ltd.     

Active power filter based on three-phase two-leg switch-clamped inverter

A novel three-phase two-leg switch-clamped inverter is presented to achieve multilevel pulse-width modulation (PWM) operation, harmonics elimination, reactive power compensation and dc-link voltage regulation. Four active switches with voltage stress of dc-link and two ac switches with voltage stress of half dc-link are used in the proposed inverter. In this paper, the proposed inverter is operated as a controllable current source to supply the necessary active power for the compensation of inverter losses, to suppress current harmonics, and to compensate the reactive power drawn from the non-linear loads. Therefore, the balanced and sinusoidal line currents are drawn from the ac source. Two control loops are used in the adopted control scheme to maintain the constant dc-link voltage (outer loop with low-bandwidth control) and to achieve the line current command tracking (inner 1oop with high-bandwidth control). The mathematical model of the proposed converter for the operation active power filter is derived and the control scheme is provided. Computer simulations and experimental results based on a laboratory scale-down prototype are presented to verify the effectiveness of the proposed control scheme.