Reduction in Ripple Current and Self‐Inductance by Using Electromagnetic Coupling of Reactor

To produce DC current by using a multiphase reversible chopper, smoothing reactors are needed. When smoothing reactors are employed, the chopper device becomes large and heavy, especially if electromagnetic interference is avoided. The reduction in the ripple current by electromagnetic coupling contributes to making the chopper device smaller and lighter. We deduced the relationships among the ripple current amplitude, duty factor, and electromagnetic coupling coefficient. To determine the loss and gain, we introduced the ratio of the amplitude of the ripple current in each phase and in the total combined current of the multiphase chopper system to that of the ripple current in a one‐phase chopper, A_ph, A_sum, respectively. This value indicates the reduction not only in the ripple current amplitude but also in the self‐inductance. The minimum value of the above‐mentioned ratio obtained analytically is accurately determined. We derived the minimum values and obtained the range within which reduction of the ripple current amplitude for both each phase and total combined is achieved. Finally, we applied an optimal electromagnetic coupling coefficient to the design of on‐board reactors of electric railway vehicles. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 186(2): 68–82, 2014; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.22480     

Dynamic model development and control for multiple‐output flyback converters in DCM and CCM

Multiple‐output flyback converters are widely used in switching power supplies due to their low component count and cost‐effective structure. The main problem of this structure is how to balance output voltages in different load conditions. This paper proposes a new approach for single‐input multiple‐output flyback converters operating in DCM and CCM by a small‐signal averaged model. The averaged model is derived by presenting the piecewise‐linear waveform for the inductor currents inside the converter. In DCM, the magnetizing current and currents through the output windings reach zero when the switch is turned off. In CCM, the magnetizing current of the converter is continuous over a switching interval and this possibility exists that only some of the output diodes completely conduct when the switch is off. The proposed model of the converter can be used in a wide range of operations within identical and non‐identical loading conditions. Using a laboratory prototype, several case studies and input‐to‐output transfer functions are considered to verify the proposed model. The controller design is performed for the both CCM and DCM, and then dynamic characteristics of the overall system are evaluated.     

Analysis of high-power factor AC-DC boost converter

This paper presents analysis of a high-power factor ac-dc converter with a boost converter operating in the discontinuous conduction mode (DCM) and the critical conduction mode (CRM). The converter can be expressed by a nonlinear differential equation for each mode. The equation in DCM is solved analytically by separating its variable (output voltage) into two terms of a ripple component and a direct component, and by linearizing the equation for the ripple component. On the other hand, the equation in CRM can be solved analytically. Furthermore, the source current waveform of the converter is expanded into the Fourier series. As a result, the output voltage, its ripple and the power factor of the converter in DCM and CRM are derived as a function of the circuit parameters, respectively, and verified experimentally. These equations exhibit clearly the effect of each circuit parameter of the converter and the difference between the converter in DCM and in CRM. The converter operating in CRM produces sinusoidal ac current with unity power factor.     

Analysis and design of a push–pull DCM boost power factor corrector

A novel power factor corrector (PFC) composed of two‐phase discontinuous conduction mode (DCM) boost PFCs and a coupled inductor is proposed in this paper. By coupling the two‐phase boost inductors into the same magnetic core, both the circuit volume and the input ripple current are reduced. Therefore, the power factor (PF) value and the power density are improved. In addition, the output capacitor size can be smaller. The proposed topology distributes the input current and output current equally for the two phase modules. A cut‐in‐half duty cycle can decrease the conduction losses of the switches, and both the turns and diameters of the inductor windings, which help more in the reduction of the circuit volume. The advantages of a DCM boost PFC, such as natural zero‐current‐switching (ZCS) of the output diode, a natural PFC function and the simplified EMI filter design, are maintained. Detailed analysis and design of the proposed topology and the experimental results on a prototype with a 380‐V output voltage and a 200‐W output power are provided. Copyright © 2011 John Wiley & Sons, Ltd.     

驱动LED串的DCM升压转换器简化分析（2）——实际考虑

固定频率升压转换器采用不连续导电模式（DCM）工作,能够有效地用于快速调光操作,提供比采用连续导电模式（CCM）工作的竞争器件更优异的瞬态响应,这种转换器非常适合于以恒流模式驱动LED串。但驱动LED的升压转换器的交流分析,跟使用标准电阻型负载的升压转换器的交流分析不同,在推导最终的传递函数时必须非常审慎。本文分为两个单元：⑴理论分析,介绍如何推导驱动LED串的升压转换器的小信号响应;⑵实际考虑,深入研究实施方案,并验证经验结果及与理论推导比较。     

PAM inverter system with power-factor-corrected converter

In most cases, PWM power-factor-corrected (PFC) converters are constructed from a diode rectifier and an active power circuit such as a boost or buck-boost chopper. Besides the PFC operation, the active power circuit can control the dc output voltage. The output voltage of the PAM inverters is controlled by varying the level of the dc input voltage. The PAM method reduces the voltage and current stresses of the inverter and motors. This paper proposes a new PAM inverter system with high power factor converter to obtain a sinusoidal input current. The proposed PAM method to reduce the torque ripple in the induction motor can reduce switching losses by providing a pausing interval where the switching operation stops during part of one period. © 1998 Scripta Technica, Electr Eng Jpn, 124(2): 43–52, 1998     

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     

Design and implementation of a new high step-up DC-DC converter for renewable applications

In this paper, a new structure for a DC-DC boost converter is proposed. The presented converter provides a high voltage transfer gain with lower duty cycle. Low current and low voltage stress on the switch, enlarged area of operating in continuous conduction mode (CCM), reduced size of the inductors, and the input filter are the main advantages of the proposed converter. The high voltage transfer gain with low number of elements has made it suitable to implement. Hence, using only one switch has made the control of the proposed converter easy. Besides, decreased switching losses and higher efficiency are obtained. The proposed structure is a combination of the Luo converter and a booster unit, which its analysis is studied in three modes, CCM, boundary conduction mode (BCM), and discontinuous conduction mode (DCM). Furthermore, in order to validate the analysis and feasibility of the proposed converter, the experimental results are developed on a low power prototype.     

EFFECTS OF LOAD INDUCTANCE ON THE RIPPLES OF MULTIPHASE CHOPPER CONTROLLED DC MOTOR DRIVE

ABSTRACT

This paper derives simple expressions to calculate the ripple currents and voltage of a multiphase chopper control DC motor drive. A typical example is considered and the results of the simple equations are compared with those obtained from the solutions of the differential equations without approximations. The effects of the load current ripple and the multiphase operation of choppers on the ripple voltage and current of the ‘LC’ input filter are also evaluated.     

High‐efficiency current‐doubler rectifier with low output current ripple and high step‐down voltage ratio

This paper presents a current‐doubler rectifier with low output current ripple and high step‐down voltage ratio. In the proposed rectifier, two extra inductors are introduced to extend the duty ratio of the switches, which in turn reduces the peak current through the isolation transformer as well as the output current ripple; two extra diodes are used to provide discharge paths for the two extra inductors. To highlight the merits of the proposed rectifier, its performance indexes, such as voltage gain function, secondary winding peak current of the isolation transformer, and output current ripple, are analyzed and compared with the conventional current‐doubler rectifier. In this paper, a zero‐voltage‐switching phase‐shift full‐bridge converter with the proposed rectifier with an input voltage of 400 V, output voltage of 12 V, and full load power of 500 W has been implemented and verified, and experimental results have shown that 90% conversion efficiency could be achieved at full load. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A single‐phase buck‐boost PFC converter with output‐voltage,ripple‐reducing operation

This paper describes a new single‐phase buck‐boost power‐factor‐correction (PFC) converter with output‐voltage, ripple reducing operation. The converter consists of a conventional buck‐boost PFC converter and an additional switch to obtain a freewheeling mode of the dc inductor current, and is operated by two modulators. The first modulator controls the buck‐boost switch to obtain PFC. The other modulator controls the square value of the instantaneous dc inductor current to perform the output‐voltage‐ripple‐reducing operation. In the two modulations, the time integral value of the input and output currents in each modulation period are controlled directly and indirectly, respectively. Thus, modulation errors or undesirable distortions of the input current and output voltage ripple are eliminated even if the dc inductor current produces large ripple in a low‐frequency range. The theories and combination techniques for the two modulators, implementation, and experimental results are described. © 1998 Scripta Technica, Electr Eng Jpn, 126(2): 56–70, 1999     

两开关伪连续导电模式Buck-Boost功率因数校正变换器

提出两开关伪连续导电模式(pseudo continuous conduction mode,PCCM)Buck-Boost功率因数校正(power factor correction,PFC)变换器及其控制策略。利用两开关PCCM Buck-Boost PFC变换器电感惯性模态所提供的一个额外控制自由度,可实现单位功率因数控制,并明显改善传统单开关Buck-Boost PFC变换器、两开关连续导电模式(continuous conduction mode,CCM)Buck-Boost PFC变换器和两开关不连续导电模式(discontinuous conduction mode,DCM)Buck-Boost PFC变换器的性能。与两开关DCMBuck-Boost PFC变换器相比,两开关PCCM Buck-Boost PFC变换器减小了电感电流纹波。仿真与实验结果表明,两开关PCCM Buck-Boost PFC变换器的负载动态响应速度明显快于传统的两开关CCM和DCM Buck-Boost PFC变换器。     

驱动LED串的DCM升压转换器简化分析(1)——理论分析

固定频率升压转换器采用不连续导电模式(DCM)工作,能够有效地用于快速调光操作,提供比采用连续导电模式(CCM工作的竞争器件更优异的瞬态响应,这种转换器非常适合于以恒流模式驱动LED串。但驱动LED的升压转换器的交流分析,与使用标准电阻型负载的升压转换器的交流分析不同,在推导最终的传递函数时必须非常审慎。本文分为两个单元:⑴理论分析,介绍如何推导驱动LED串的升压转换器的小信号响应;⑵实际考虑,深入研究实施方案,并验证经验结果及与理论推导比较。     

一种基于NCP1653电流连续导通模式的功率因数校正器设计

介绍一种固定频率的电流连续导通模式(CCM)的功率因数校正器的设计,它的主要特点就是在比较宽的输入电压范围内可以做到很高的功率因数和转换效率,减小了输入电流的总的谐波含量(THD)。它具有固定电压输出和跟随升压两种输出模式软启动功能,同时还具有软启动功能。实验表明,这种固定频率的CCMPFC芯片实现了这些功能。     

Reduction of Ripple Current Loss by Electromagnetic Coupling of Air‐Core Reactors

To reduce the loss due to ripple current in a multiphase current‐reversible chopper, we investigated electromagnetic coupling of an air‐core reactor. We derived the relationship between the amplitude of the ripple current, the duty factor, and the electromagnetic coupling coefficient, and used the results to estimate the effects of electromagnetic coupling in the design of a train energy storage system. We built reactors with electromagnetic coupling coefficients of 0.93 and 0.60. These reactors employed a new winding structure that provides an optimal electromagnetic coupling coefficient. The mass of the former type of reactor was increased by 4.4% over the conventional design, and that of the latter type of reactor was decreased by 17%. Finally, we tested the new reactors. When the chopper employs the former type of reactor and operates with equal‐phase switching and cumulative coupling, the loss due to ripple current is decreased by 11%. When the chopper employs the latter type of reactor and operates with shift‐phase switching and differential coupling, the loss is decreased to 31%. The test showed that the calculated relationships agreed with the measured values.     

一种带隔离的单相三电平功率因数校正电路

在原有Boost单相三电平功率因数校正电路的基础上,提出了一种带隔离的三电平两级功率因数校正电路的拓扑及其控制方法。直流侧工作在DCM/CCM的临界模式,使用UC3852芯片控制PFC功率开关管,使其在零电流条件下开关。最后,设计了一个250W,50kHz单相三电平两级功率因数校正电路,并给出了仿真和实验结果。     

一种新型不连续导电模式下的单级交错PFC

本文提出了一种新型交错单级功率因数校正电路(PFC)。为了实现功率因数校正和减小电感体积，boost电感工作在不连续导电模式。此单级PFC电路采用两个boost电路交错运行，减小了输入EMI滤波器的尺寸和开关电流应力，同时也减少了输出纹波。在介绍电路工作原理的基础上，对其输入电流进行了分析，给出了仿真与实验结果。     

P-type non-isolated boost DC-DC converter with high voltage gain and extensibility for DC microgrid applications

In this paper, the concept of converter design, using the least number of elements and achieving high voltage gain at the low duty cycle, is proposed for the microgrids. One of the important issues in the microgrids is boosting the low voltage output of sources to the utility voltage level. Therefore, the step-up DC-DC converters are widely used in these systems to attain the utility voltage. The benchmarking of the converters mainly in terms of the voltage gain, efficiency, the number of active and passive components, stresses on semiconductors, and simplicity is considered. In this paper, a new extendable non-isolated boost DC-DC converter is presented. Comparing the conventional boost converter, the basic structure of the proposed converter has a high voltage gain and reduced stress on the switch. To increase the voltage gain, the basic structure of the proposed converter can be easily extended. The modulation technique employed is high-frequency pulse-width modulation (PWM). The detailed analysis of the proposed converter in continuous current mode (CCM) and discontinuous current mode (DCM) is presented. The relations between currents and voltages and the voltage gain in CCM and DCM are obtained. Experimental results are carried out to verify theoretical concepts by using the hardware prototype.     

基于固定关断时间控制的Boost PFC电路研究

在详细分析固定关断时间(Fixed-off Time,简称FOT)控制原理的基础上,提出了将FOT用于Boost PFC时的方法.仿真验证了该方法的可行性,并利用DSP作为控制核心设计了一个Boost PFC电路.仿真和实验结果表明,该方法能有效减小输入电流谐波,提高功率因数.     

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.