State-plane analysis of zero-voltage-switching resonant DC/DCconverters

The state-plane analysis technique is established for the zero-voltage-switching resonant DC/DC power converter family of topologies, namely the buck, boost, buck-boost, Cuk, sepic, and dual-sepic converters. The state plane provides a compression of information, which allows the designer to examine the nonlinear dynamics of resonant converter operation. Utilizing the state plane, modes of resonant converter operation are examined. Expressions are derived for the switching frequencies at the boundaries between these modes and at the boundary of energy conversion     

AC/DC converter topologies for the Space Station

A new class of AC/DC converter topologies (Type-1 converters) is described, suitable for use in an advanced single-phase sine-wave voltage, high-frequency power distribution system, of the type that was proposed for a 20 kHz Space Station primary electrical power distribution system. The converter comprises a transformer, a resonant network, a current controller, a diode rectifier, and an output filter. The input AC voltage source is converted into a sinusoidal current source using the resonant network. The output of this current source is rectified by the diode rectifier and is controlled by the current controller. The controlled rectified current is then filtered by the output filter to obtain a constant voltage across the load. Three distinct converter topologies, Type-1A, Type-1B, and Type 1-C, are described, and their performance characteristics are presented. All three types have a close-to-unity rated power factor (greater than 0.98), low total harmonic distortion in input current (less than 5%), and high conversion efficiency (greater than 96%)     

永磁驱动重构型车载充电机三相DC/DC变流器的研究

提出了一种新型永磁驱动重构型车载充电机三相DC/DC变流器集成系统。该集成系统将永磁驱动的电机绕组和DC/AC逆变器重构成车载充电机实现电动汽车驱动-充电的集成,具有空间利用率高、充电快速和可靠性高等特点。分析了集成系统的结构和工作原理,推导了充电系统的三相DC/DC变换器数学模型。在此基础上,利用MATLAB/Simulink仿真软件搭建了驱动-充电集成系统仿真模型,对同步脉宽调制(PWM)控制和交错PWM控制策略进行仿真研究,分析对比了交流侧电压电流、直流侧电机绕组电感电流和直流侧电压波形。仿真结果表明,与交错PWM控制策略相比,同步PWM控制策略下该新型结构充电系统具有更好的运行性能。     

Single-phase power-factor-correction AC/DC converters with threePWM control schemes

Three pulse-width modulation (PWM) control schemes for a single-phase power-factor-correction (PFC) AC/DC converter are presented to improve the power quality. A diode bridge with two power switches is employed as a PFC circuit to achieve a high power factor and low line current harmonic distortion. The control schemes are based on look-up tables with hysteresis current controller (HCC) to generate two-level or three-level PWM on the DC side of diode rectifier. Based on the proposed three control schemes, the line current is driven to follow the sinusoidal current command which is in phase with the supply voltage, and two capacitor voltages on the DC bus are controlled to be balanced. The simulation and experimental results of a 1 kW converter with load as well as line voltage variation and shown to verify the proposed control schemes. It is shown that unity PFC is achieved using a simple control circuit and the measured line current harmonics satisfy the IEC 1000-3-2 requirements     

Novel single-phase AC/DC converter with two PWM control schemes

A novel single-phase AC/DC converter with two pulsewidth modulation (PWM) schemes is proposed to draw a sinusoidal line current with nearly unity power factor, achieve balanced neutral point voltage and regulate the DC bus voltage. With the aid of neutral point clamped scheme, a three-level voltage pattern is generated on the AC side of the proposed rectifier. To track the tine current command derived from a voltage controller and a phase-locked loop circuit, a hysteresis current control scheme is used in the inner loop control. A capacitor voltage compensator is employed to achieve the balanced neutral point voltage. To investigate the effectiveness of the proposed control scheme, the simulation and experimental results based on a laboratory prototype circuit are performed.     

并联H桥DC/DC变换器软开关技术研究

与传统的Buck电路相比,基于H桥并联的DC/DC变换器可以实现电压的双极性输出和故障时的冗余控制,非常适合用于大功率电动机正反转控制的场合。分析了并联H桥型DC/DC变换器的结构组成和双脉宽调制(PWM)模式。为了降低双脉宽调制下H桥型DC/DC变换器的开通和关断损耗,对无源软开关技术进行了分析,重点探讨了RCD缓冲电路和最小应力缓冲电路之间的性能差异,指出最小应力软开关技术可以获得更好的软开关性能,并就将其用于双脉宽调制下的并联H桥DC/DC变换器进行了仿真研究。仿真结果表明:最小应力软开关技术用于双脉宽调制下并联H桥DC/DC变换器时,可以实现开关管的零电压开通和零电流关断。     

大容量直驱风电机组级联直流组网系统设计

传统交流组网风电场系统存在多次电能转换、成本高的问题。针对这个问题,设计了一种大容量直驱风电机组级联直流组网海上风电场系统,其直接将每台机组的直流输出级联形成高压直流进行传输,而无需额外的海上升压站平台。风电机组采用了永磁直驱风力发电机及其变流器,其中变流器包括了AC/DC单元和DC/DC单元,并设计了控制策略,即通过DC/DC单元的占空比调节来实现电流的持续输出和最大功率跟踪。陆基逆变电站采用晶闸管型逆变器,设计了工作模式和控制策略,其主要功能是实现高压直流链路的电压电流调节。最后,基于PSCAD/EMTDC仿真平台,搭建了容量为150 MW的风电场系统进行了仿真计算,计算结果验证了该系统具有较高的鲁棒性和对风速变化的适应性,同时每个机组都能独立的实现最大风能捕获。     

基于UCC2810多路输出DC/DC模块的设计

介绍了双路输出、双路闭环控制脉宽调制器UCC2810的功能和电路设计、功率转换电路设计。与单路闭环控制或间接稳压方案相比较,采用UCC2810设计的双路输出DC/DC模块,从根本上消除了交叉调整率的影响,适用于负载不平衡的应用。具有功耗低、电路设计一致性好等优点。     

Novel AC-DC and DC-DC converters with a diode-capacitor multiplier

This paper presents a transformerless ac-dc and or dc-dc converter with a high output voltage multiplicity, which contains only one switch. The converter consists of an inverter and a diode-capacitor multiplier (DCM) and provides a voltage gain equal to double the number of multiplier steps. In the case of ac-dc conversion the proposed converter offers a practically unit power factor and provides a sine wave input current. The analysis of the steady state as well as the transient behavior of the DCM is given and simplified equivalent circuits are proposed. The prototype of the DCM has been built and tested to show the validity of the proposed converter. The theoretical analysis, the computer simulation results, and the experimental testing results are in good agreement.     

火电辅机变频器低压穿越直流电压补偿及其控制

针对火电辅机变频器因厂用电压跌落而触发闭锁,造成发电机组停机的问题,设计了基于变频器直流母线电压补偿的辅助穿越装置。辅机变频器采用直接转矩控制,低压穿越装置主电路采用三重交错并联升压变换器结构,在电压跌落期间维持变频器直流母线电压稳定,同时减小输出电流高频纹波。考虑到并联模块参数差异造成的均流问题,提出在传统电压电流双闭环控制的电压外环加入均流环的解决方法,消除环流,使开关管电流应力更为均衡。由于控制系统具有非线性、强耦合的特点,传统PI控制器存在局限性,所以利用模糊控制算法优化PI控制器参数整定,改善其性能。最后用仿真验证了所提方法的有效性。     

应用于超级电容储能系统的双向DC/DC变换器混沌控制方法研究

超级电容储能系统(SCESS)主要通过对双向DC/DC变换器进行控制来快速平抑直流母线电压的波动。为了抑制控制过程中所产生的一些分岔和混沌现象,提出了一种应用于SCESS的混沌控制方法。分析了该方法的控制原理,并根据非线性动力学理论建立了双向DC/DC变换器的离散迭代模型；然后设计了一种能够自动调节补偿斜率的混沌控制信号；最后对该信号作用下的异步切换函数和同步切换映射式进行了数值求解,从而绘出系统分叉图。通过仿真和试验证明,该方法能够有效抑制SCESS的分岔和混沌现象,提高了系统的稳定工作范围和动态响应速度。     

单端正激ZVT功率变换器实现

介绍一种单端正激工作方式的零电压过渡（ＺＶＴ）软开关ＤＣ－ＤＣ变换器;描述该变换器的原理和特征;给出了应用ＺＶＴ软开关技术和集成控制块ＳＧ３５２５Ａ的２４Ｖ／９ＡＤＣ－ＤＣ变换器电路和实验结果。     

高压直流输电晶闸管阀用饱和电抗器的设计

高压直流换流阀用饱和电抗器的作用是抑制流经晶闸管的电流变化率,限制晶闸管产生的电压,提高晶闸管换流阀分布电压的均匀性。主要研究高压直流换流阀用饱和电抗器的理论设计、结构排布及线圈选取等方法,具有一定的实际应用价值。     

High power factor AC/DC/AC converter with random PWM

A three-phase AC/DC/AC converter is presented with a power factor preregulator to improve the power quality in the input side and a pseudorandom noise generator to reduce the emitted acoustic noise and the mechanical vibration for an induction motor drive. The space vector modulation with hysteresis current control for a voltage source rectifier is adopted to simplify the hardware circuit. A control scheme is presented to drive the supply current following the reference current. The amplitude of reference current for the pulsewidth modulation (PWM) rectifier is derived from the DC bus voltage regulator and the estimated output power. Random switching frequency technique for a three-phase PWM inverter system to reduce the annoying tonal noise and resonant vibration from an induction motor is described. By randomly varying the instantaneous PWM switching frequency from one cycle to the next, the frequency distribution of harmonics is spread in a wide frequency range. The major advantage for using such a strategy is the nonrepetitive output spectral characteristic that results in reduction of torque pulsations in motor drive systems. The nearly unity power factor at the three-phase rectifier and the absence of acoustic noise concentrated at the specific tones which is usually present with conventional sinusoidal modulation are verified by the experimental tests     

Current-fed multiresonant isolated DC-DC converter

A novel topology, current-fed multiresonant dc-dc converter (CF-MRC) was studied theoretically and experimentally. The new topology differs from previously described current-fed push-pull parallel-resonant topologies in the fact that the output is coupled to the current of the resonant inductor and in the addition of a second capacitor across the transformer. The main features of the proposed converter are an inherent protection against a short and open circuit at the output, a high voltage gain and zero voltage switching (ZVS) over a large range of output voltage. These characteristics make it a viable choice for applications, such as a high voltage capacitor charger, that require controllable current sourcing over a wide output voltage swing.     

The effect of the magnetizing inductance on the small-signaldynamics of the isolated Cuk converter

The magnetizing inductance of the isolated Cuk converter introduces an undesirable pair of closely spaced complex zeros and poles, or a glitch, in the control-to-output transfer function. Limited analysis and experimentation in the past have shown that sufficient increase in the magnetizing inductance or manipulation of the ratio of the capacitances of the energy transfer capacitors can reduce the glitch. In this work, the isolated Cuk converter with coupled input and output inductors has been studied and the dependence of the glitch on various circuit parameters has been determined analytically. A condition has been derived for the ratio of the capacitances of the two energy transfer capacitors which completely eliminates the glitch at a given operating point. With this condition satisfied, it is shown that the energy transfer capacitors can be easily damped by a simple RC network to eliminate the glitch from a wide range of operation about an operating point     

异步电机起动/发电系统起动向发电的转换研究

用异步电机与电力电子变换器结合构成的起动/发电系统作航空电源是一个很有意义的课题。对异步电机起动/发电系统中起动向发电的转换进行了研究,提出充分利用系统中变换器可快速控制定子磁链转速的特点,改变电磁转矩的方向,实现起动到发电的转换。详细介绍了转换过程控制方案,该方案可实现起动到发电的平滑转换,且在进入发电状态后直流母线电压由起动电源电压自动增长到所需的发电电压,最终稳定发电。最后给出了仿真与实验结果。     

无刷直流电机高精度换相控制

针对无刷直流电机(BLDCM)换相期间不导通相续流而产生端电压脉冲的问题,依据反电动势(EMF)过零法原理,分析了端电压脉冲产生的原因及对反电动势过零检测精度的影响,提出了一种利用软件算法避开端电压脉冲从而实现无位置传感器BLDCM高精度换相的控制方法。首先,利用条件语句及程序运行时间差避开端电压脉冲；为了在重载情况下提高所设计程序运行时间差的容错率,提出一种减小换相续流时间的方法；最后,搭建了无传感器BLDCM试验平台对上述方法进行试验验证。试验结果证明了所提方法在不同占空比和负载下的有效性和准确性。     

Single-Stage Single-Switch Switched-Capacitor Buck/Buck-Boost-Type Converter

A new dc-dc converter featuring a steep step-down of the input voltage is presented. It answers a typical need for on-board aeronautics modern power architectures: power supplies with a large conversion ratio able to deliver an output voltage of 1–1.2 V. The proposed structure is derived from a switched-capacitor circuit integrated with a buck converter; they share the same active switch. The proposed solution removes the electromagnetic interference (EMI) emission due to the large di/dt in the input current of the switched-capacitor power supplies. Compared with a quadratic buck converter, it presents a similar complexity, a smaller reduction in the line voltage at full load (but less conduction losses due to smaller input inductor current and capacitor voltage), lower voltage stresses on the transistor and diodes, lower current stresses in the diodes, and smaller size inductors. A similar structure using a buck-boost converter as the second stage is also presented. The experimental results confirm the theoretical developments.