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.     

Half-bridge neutral point diode clamped rectifier for power factor correction

A high power factor rectifier based on neutral point clamped scheme is proposed. The voltage stress of each power semiconductor of the adopted rectifier is equal to the half dc bus voltage instead of full dc link voltage in the conventional switching mode rectifier. The control signals of the power switches are derived from the dc link voltage balance compensator, line current controller, and dc link voltage regulator. The hysteresis current control scheme is employed to draw a clean sinusoidal line current, high input power factor, regulated dc link voltage, and balance capacitor voltages. Three voltage levels are generated on the ac terminal of the adopted rectifier. To verify the proposed operation scheme, performance characteristics are given by the experimental results.     

Single-phase three-level rectifier and random PWM inverter drives

A novel ac/dc/ac converter topology with three-level pulsewidth modulated (PWM) scheme for the single-phase ac/dc rectifier and random PWM scheme for ac drives is proposed. In order to improve the power quality in the single-phase rectifier, a ROM-based (read-only memory) control scheme, based on hysteresis current comparator, region detector, and capacitor compensator, is used to achieve a sinusoidal line current with low current distortion. The control scheme of the adopted three-level rectifier is easy to implement. The blocking voltage of power switches is clamped to half of the dc bus voltage. To reduce the mechanical vibration from an induction motor, random pulse position PWM scheme is adopted to spread the harmonics in a wide frequency range which results in the reduction of torque pulsation in the ac motor drives. Simulation and experimental results based on the laboratory prototype circuit are presented to verify the proposed control scheme     

Novel AC line conditioner for power factor correction

A new ac line conditioner is presented for high input power factor and clean ac output voltages for isolating the linear or nonlinear loads. A three-phase two-leg switching mode rectifier with neutral-point-clamped topology is proposed to draw the sinusoidal line currents from the ac mains. The carrier-based current controller is used in the inner control loop to track the line current commands with unity power factor. The dc bus voltage controller is adopted in the outer control loop to regulate the dc-link voltage. A voltage compensator is used to balance the neutral point voltage on the dc tank. A three-phase two-leg inverter with neutral-point-clamped topology is adopted in the system to provide the clean ac output voltages to the critical or sensitive loads. The carrier-based current control scheme is adopted to improve the instantaneous output voltages. Experimental results show the validity and effectiveness of the proposed control strategy.     

ZCS-PWM boost rectifier with high power factor and low conduction losses

A new single-phase high power factor rectifier is proposed, which features regulation by conventional pulsewidth modulation (PWM), soft commutation, and instantaneous average line current control. A new zero-current-switching PWM (ZCS-PWM) auxiliary circuit is configured in the presented ZCS-PWM rectifier to perform ZCS in the switches and zero-voltage-switching (ZVS) in the diodes. Furthermore, soft commutation of the main switch is achieved without additional current stress by the presented ZCS-PWM auxiliary circuit. A significant reduction in the conduction losses is achieved, since the circulating current for the soft switching flows only through the auxiliary circuit and a minimum number of switching devices are involved in the circulating current path and the proposed rectifier uses a single converter instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter. Seven transition states for describing the behavior of the ZCS-PWM rectifier in one switching period are described. The PWM switch model is used to predict the system performance. A prototype rated at 1 kW, operating 60 kHz, with an input ac voltage of 220 V/sub rms/ and an output voltage 400 V/sub dc/ has been implemented in laboratory. An efficiency of 97.2% and power factor near 0.99 has been measured. The analysis and design of the control circuitry are also presented.     

三相电压型脉宽调制整流器定频模型预测控制

针对三相电压型脉宽调制(PWM)整流器有限控制集模型预测控制采样频率高、开关频率不固定的缺点,提出了一种定频模型预测控制方法。通过求解价值函数得到PWM整流器交流侧下一采样时刻所要输出的电压值,利用空间矢量脉宽调制技术输出计算得到的电压值,实现定频模型预测控制。仿真与试验结果表明:所提出的控制算法开关频率恒定,稳态电流谐波含量低,实现了整流器高功率因数运行。     

三相电压型PWM整流器的模糊PI控制方法

在双闭环控制的基础上,分析了整流器的模糊PI控制,建立了三相PWM整流器MATLAB/SIMULINK仿真模型。结果表明,该方法能够实现PWM整流器的高功率因数并且有良好的动态性能,从而验证了所提出方法的可行性和有效性。     

Implementation of a single-phase AC/AC converter based on neutral-point-clamped topology

A single-phase ac/ac converter based on neutral-point-clamped scheme is proposed to perform unity input power factor and to provide a stable ac voltage to the critical loads. The ac/dc rectifier part is controlled to generate a unipolar pulsewidth modulation (PWM) waveform on the ac terminal by using four power switches with voltage stress of half the dc-link voltage. The carrier-based current control scheme is employed in the inner control loop to track the line current command. To regulate the dc bus voltage, a proportional-integral (PI) control is adopted in the outer control loop. The dc/ac inverter part of the system with four power switches is employed to generate a stable and clean sinusoidal output voltage to the critical load. The instantaneous current control scheme is used to track the output voltage command. To verify the effectiveness of the proposed control algorithm, the simulation and experimental results based on a laboratory prototype were implemented and discussed.     

基于高功率因数控制的永磁同步电机无电解电容驱动系统控制策略

永磁同步电机无电解电容驱动系统因其成本与寿命的优势,在白色家电领域逐步得到广泛的应用。然而,由于使用小容量的薄膜电容取代大容量的电解电容,母线电压会以两倍工频波动,在母线电压处于波谷时,逆变器输出电压容易饱和,导致控制性能恶化,网侧电流畸变。因此,提出了一种基于高功率因数控制的转矩控制环和电压矢量修正策略,能够有效提升网侧功率因数,抑制网侧电流谐波并符合IEC 6100032标准。该算法的有效性通过仿真得以验证。     

航空机电作动器的混合整流全状态反馈控制

研究了一种适用于多电飞机供电系统的新型混合整流电路,并针对航空机电作动器负载特殊的用电特性,提出了一种基于全状态反馈的混合整流控制方法,在保证整流效果的同时,解决了负载功率短时大范围变化引起的直流电压不稳定问题。这种新型混合整流电路将二极管整流电路和脉宽调制(PWM)整流电路并联输出接负载,两者共同承担有功功率且比例可控,通过适当控制PWM电路达到网侧低谐波的目的,且当负载制动时,能量可以回馈交流侧电网。建立了混合整流器的线性化全状态数学模型,设计了基于线性二次型(LQR)最优化理论的全状态反馈控制策略。通过在MATLAB/Simulink下的建模与仿真,比较了全状态反馈控制方法与传统三状态反馈控制方法,并在机电作动器样机上进行了实验验证。仿真和实验结果表明,采用全状态反馈控制的新型混合整流方案对于功率大范围变化负载具有更好的控制性能。     

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     

一种新型交流恒功率负载仿真模型

根据闭环控制的高功率因数(HPF)脉冲宽度调制(PWM)整流器的恒功率工作特性,对交流(AC)恒功率负载(CPL)仿真模型进行了研究。采用输入电流波形跟随电压波形的方法,利用MATLAB建立了交流恒功率负载的仿真模型。在模型两端加载的电压不含谐波和含有谐波的两种情况下,模型均可以自动计算出输入电流有效值(RMS),使得模型输入平均功率保持恒定,并能生成电流波形,反映出电压谐波对电流波形的影响。模型仿真结果与实际高功率因数PWM整流器的输入波形进行了比较,验证了该模型的正确性。     

Implementation of nondeterministic pulsewidth modulation forinverter drives

A single-phase power factor preregulator to improve the power quality in the input side of an ac/dc/ac converter and a random pulsewidth modulation (PWM) to reduce the emitted noise energy and the mechanical vibration for an induction motor drive is proposed. The hysteresis current control (HCC) technique for a voltage source switching mode rectifier (SMR) is adopted. A control scheme is presented such that the line current is driven to follow the reference current which is derived from the dc bus voltage regulator and the output power estimator. A random pulse position technique for a three-phase voltage source inverter system to reduce the noise energy and resonant vibration from ac machine drive is described. By randomly varying the instantaneous pulse position in each switching frequency, the frequency distribution of harmonics is spread in a wide frequency range which results in reduction of torque pulsations in the ac motor drive systems. To investigate the proposed control scheme, experimental tests based on a laboratory prototype were implemented to show the nearly unity power factor at the SMR and reduce the noise energy concentrated at the specific tones     

Full control of a PWM DC-AC converter for AC voltage regulation

The design and implement action of a DSP-based fully digital-controlled single-phase pulsewidth modulated (PWM) dc-ac converter for ac voltage regulation is described. The proposed multiloop digital controller (MDC) consists of a current controller, a voltage controller, and a feedforward controller. This MDC was realized using a single-chip digital signal processor (DSP). The PWM gating signals are determined at every sampling instant by the proposed multiloop digital control scheme using a set of detected feedback signals. A software current control; scheme has been developed to achieve fast current control of the PWM inverter and decouple the inductor of the output filter. Experimental results have been given to verify the proposed digital control scheme. The constructed DSP-based PWM dc-ac converter system can achieve fast dynamic response and with low total harmonic distortion (THD) for rectifier type of loads     

单相PWM整流电路控制方法及仿真分析

分析单相PWM整流电路的结构、工作原理和控制方法,通过选择适当的工作模式和工作时序,可使PWM整流电路输出直流电压稳定。将正弦脉宽调制技术应用于PWM整流电路,使其交流侧输入电流非常接近正弦波,且与输入电压同相位。同时调节交流侧电流的大小和相位,使能量在交流侧和直流侧双向流动。在建立基于Simu-link7.6的仿真模型基础上,通过分析PWM整流电路各处电压、电流波形,验证其控制方法及仿真设计的正确性。     

一种具有电压支撑功能的改进无功注入策略

电压跌落是输配电系统面临的最严重的问题之一。随着分布式光伏电源在电力系统中的渗透率越来越高,国内外最新标准要求光伏逆变器必须具备低电压穿越能力。为了消除有功功率振荡,在传统的正/负序控制基础上提出了一种改进的有功/无功注入策略;针对现有电压支撑方法缺乏电压抬升范围控制,将三相电压幅值作为控制目标,详细推导了适用于不同电压跌落情况下的数学模型,得出为保证各相电压均保持在安全运行范围之内所需注入无功功率参考值。仿真结果验证了所提策略的正确性和有效性。     

基于SVPWM的高功率因数整流器研究

介绍了三相电压型PWM整流器的数学模型和空间矢量PWM(SVPWM)控制技术,并根据设计要求完成了主电路中相关参数的设计。实验发现,采用SVPWM电流控制技术能够使网侧电压与电流同相位,表明电压型PWM整流器实现了高功率因数整流。     

Implementation of a three-phase high-power-factor rectifier with NPC topology

A three-phase four-wire power factor corrector based on neutral-point-clamped (NPC) topology is adopted to reduce the current harmonics and increase the input power factor. Using the NPC topology, the voltage stress of power switches can be reduced to the half of the dc-link voltage. With the dc-link voltage controller and the phase locked loop circuit, the balanced and sinusoidal line currents can be drawn from the ac supply system under the balance and unbalance mains voltages. The hysteresis current comparators are adopted in the current control loop to track the line current commands. Three voltage levels are generated on the ac terminal to the neutral point. Simulations and experiments are provided to verify the validity and the effectiveness of the proposed control scheme.     

一种新型井下架线电机车供电电源设计

提出了一种新型的基于单周期控制的单位功率因数整流器为井下电机车供电。该电源由维也纳整流级和高频隔离DC-DC变换级两级功率变换器级联构成,但控制电路采用一级协调控制。电路控制简单,不需要乘法器和输入电压检测就可以实现单位功率因数运行,且可以降低开关器件一半的电压应力。详细分析了新型整流电路的基本工作原理和双闭环控制策略,并通过仿真和试验对此新型电路拓扑及其相应控制策略的正确性进行了验证。