A novel switching-mode ac buck-boost voltage regulator

This paper presents a novel switching-mode ac/ac voltage regulator using a bidirectional buck-boost converter. Since it operates at high frequency, the proposed system can be designed compactly, and there is a wide range of input voltage from 1/2 to 2 per unit with fast dynamic response and low harmonics. In order to verify the accuracy of the proposed method, a 500 W prototype has been implemented in the laboratory. From the experimental results, the regulation of the output voltage is within less than 1%. Moreover, the total harmonic distortion (THD) of the input current under full load is 2.46% and the output voltage has a THD of 1.77%.     

A novel unity power factor input stage for AC drive application

In this paper, a new method of improving the input current total harmonic distortion (THD) as well as power factor of a three-phase suppressed-link rectifier-inverter is presented. This proposed method makes use of a novel controlled diode rectifier. The technique involves the use of bidirectional switches across the front-end rectifier, and a dSPACE based intelligent control algorithm. The operation of the converter is fully analyzed and design example provided. The main feature of the topology is low cost, small size, high efficiency and simplicity, and is excellent for retrofitting front-end rectifier of existing ac drives, UPS etc.     

A novel suppressed-link rectifier-inverter topology with near unity power factor

This work describes a novel method in improving the input current total harmonic distortion (THD) as well as the power factor of a three-phase suppressed-link rectifier-inverter circuit. This proposed method makes use of only three bi-directional low power static switches with a relatively simple gating circuit. This paper illustrates how the proposed method is superior in reducing the input current THD of a rectifier-inverter set to about 5%, which is in line with the requirements of IEEE standard 519-1992. This is accomplished without the use of any filter or complex wave shaping techniques. A delta-modulated (DM) voltage source inverter (VSI) with proportional integrator forms the output stage of the converter. It helps to provide constant volts per hertz operation without the need for additional feedback circuitry and complexity. Moreover, this novel DM technique also helps to provide a smooth transition from the pulse width modulation (PWM) to square wave, hence allowing full utilization of the DC bus voltage.     

A novel single-phase soft-switched rectifier with unity power factor and minimal component count

A novel, single-phase soft-switched boost AC-DC rectifier that operates with power-factor correction is proposed in this paper. The rectifier is a modified boost voltage-doubler converter well suited for low-line-input applications. It operates with fewer conduction losses and half the switch voltage stresses found in a standard boost converter. Soft switching in the converter is achieved using a zero-current-switching quasi-resonant technique. In the paper, the converter and its modes of operation are discussed and analyzed. The method of control is explained, and a design procedure is derived and then demonstrated with an example. The feasibility of the converter is shown with experimental results obtained from a prototype.     

Novel unity power factor circuits using zero-vector control forsingle-phase input systems

This paper proposes two novel circuits which realize a unity input power factor single-phase to three-phase converter with a motor load. The power supply is connected to the neutral point of the motor, and the three-phase inverter is controlled to act also as a virtual AC/DC power converter leg. This virtual leg is controlled by zero vectors of the three-phase inverter. The main features of these circuits are as follows: no inductive components are required; a reduction in the number of switching devices compared with conventional topologies; and motor current increases because converter input current also flows through the motor windings. A full-bridge converter can be built using the same number of switching devices as the conventional half bridge and with no need for a capacitive leg with an accessible neutral point. In this paper, the proposed full-bridge-type circuit is experimentally tested using a 750-W induction motor as load     

Analysis and design of single-controlled switch three-phaserectifier with unity power factor and sinusoidal input current

This paper describes a new low-cost three-phase AC-DC high-power/low-harmonic-controlled rectifier and its analysis, design, and performance. The circuit consists of a three-phase diode-bridge rectifier, followed by a boost stage containing only one switch and one boost inductor. The proposed converter is used to automatically draw sinusoidal input-current waveforms with high efficiency. This is achieved with discontinuous-input voltage to the rectifier and with a discontinuous-inductor-current mode of operation of the boost converter. By using a simplified single-phase model and symbolic analysis method, analytical equations are obtained and used for design     

新型多路输出数字调压电路的设计

研究了一种新型多路输出数字调压电路。以FPGA为核心,利用其丰富的I/O口,实现多路电压同时输出。待转换的数据经USB2.0接口输入FPGA内部FIFO中,减少电压配置时间。采用高压运放芯片,工作于非对称供电模式。实验结果表明,电压调节范围-39V~+49.95V,步进调节灵敏度为0.0244V,最大输出电流50mA,纹波电压小于2mV。     

A new ZVS-PWM unity power factor rectifier with reduced conductionlosses

This paper introduces a new single-phase high power factor rectifier, which features regulation by conventional PWM, soft commutation and instantaneous average line current control. Furthermore, thanks to the use of a single converter, instead of the conventional configuration composed of a four-diode front-end rectifier followed by a boost converter, a significant reduction in the conduction losses is achieved. A prototype rated at 1.6 kW, operating at 70 kHz, with an input AC voltage of 220 Vrms and an output voltage of 400 V_DC has been implemented in the laboratory. An efficiency of 97.8 % at 1.6 kW has been measured. Analysis, design, and the control circuitry are also presented in the paper     

A unity power factor PWM rectifier with DC ripple compensation

This paper presents a new topology for a pulsewidth modulation (PWM) rectifier which achieves unity power factor on the AC supply side and ripple reduction on the DC output side. The main circuit of this rectifier consists of a conventional PWM rectifier and a pair of additional switches. The switches and PWM rectifier are controlled such that the ripple current on the DC line is reduced, and unity power factor is achieved on the AC line. As a result, this circuit does not require a large DC capacitor or a passive LC resonant circuit. Furthermore, control of the additional switches and PWM rectifier requires only a simple control circuit. The effectiveness of this circuit was confirmed by experiments and analysis. The rectifier is useful for uninterruptible power systems (UPSs) and DC power supplies, especially for cases in which batteries are connected to the DC line     

Single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor

A single-stage line-coupled half-bridge ballast with unity power factor and ripple-free input current using a coupled inductor is proposed. The proposed power-factor-correction circuit can achieve unity power factor and ripple-free input current using a coupled inductor. A saturable transformer constituting the self-oscillating drive limits the lamp current and dominates the switching frequency of the ballast. The proposed ballast has high energy efficiency, low cost, and high reliability compared to the conventional high-power-factor electronic ballasts. Experimental results obtained on a 30-W fluorescent lamp is discussed.     

A novel technique to achieve unity power factor and fact transientresponse in AC-to-DC converters

This paper presents a novel power factor correction technique for single-phase boost type AC-to-DC converters in continuous conduction mode. Instead of using the inductor current or switching device current, in this paper, the diode current in the boost converter is used to formulate the duty ratio of the switch in a special way which makes the input current sinusoidal and in phase with the input voltage. To improve the dynamic performance and minimize the input current harmonic components, a new double-injection compensation method is employed in the voltage feedback loop. The power factor corrector has the following advantages: (1) operation with constant switching frequency; (2) elimination of input voltage sensing, error amplifier in the current loop and multiplier in the output voltage feedback loop; (3) minimal total harmonic distortion in the input current; (4) fast dynamic response of the output voltage loop; and (5) simple implementation of the control circuit. The principles of operation of the proposed control scheme are explained. Simulation and experimental results are presented to verify the feasibility of the control strategy     

Predictive digital control of power factor preregulators with input voltage estimation using disturbance observers

The paper presents a fully digital control of single-phase boost power factor preregulators (PFPs) based on inductor (or switch) current and output voltage measurements. Input voltage sensing is avoided using a disturbance observer, which provides a waveform proportional to the rectified input voltage. The proposed solution is based on a multiloop structure for PFPs with an internal deadbeat current control and a conventional outer voltage control, possibly with fast dynamic response. The resulting control algorithm is simple, accurate, and robust with respect to parameter mismatch. The digital control has been implemented both in a field programmable gate array and in a digital signal processor (TMS320F2812), to test the proposed algorithm with different control delays. Experimental results on a single-phase boost PFPs show the effectiveness of the proposed solution.     

A family of PFC voltage regulator configurations with reducedredundant power processing

This paper discusses a systematic method for deriving basic converter configurations that achieve power factor correction (PFC) and voltage regulation. The discussion begins with a general three-port representation of power supplies that provide PFC and voltage regulation. Based on this representation and a power flow consideration, a systematic procedure is derived to generate all possible minimal configurations. Among these configurations, only a few have been known previously and used in practice. It is found that the efficiency of PFC voltage regulators can be improved by reducing the amount of redundant power to be processed by the constituent converters. A systematic circuit synthesis procedure is proposed for creating PFC voltage regulators with reduced redundant power processing. Experimental measurements verify the improved efficiency     

A novel high-performance voltage regulator for single-phase ACsources

Regulation of load voltage in single-phase applications is becoming an important issue for critical loads. This paper presents a novel high-performance single-phase voltage regulator which has a common arm between the rectifier and inverter, and adopts an appropriate switching strategy. The proposed voltage regulator employs six switches and can be implemented by only one three-phase inverter module. The proposed voltage regulator has the capability of delivering sinusoidal input current with unity power factor, good output voltage regulation, and bidirectional power flow. For these purposes, a fully digital controller is designed and implemented using a TMS320F240 digital signal processor. In addition, a novel low-cost AC capacitor is also presented. This type of capacitor requires two DC capacitors and two diodes, enabling low-cost and compact manufacturing. Consequently, the complete voltage regulator system, which is mainly suitable for an uninterruptible power supply as well as reactive or nonlinear loads, can be constructed compactly and inexpensively. Experimental results are presented to verify the feasibility of the proposed voltage regulator system     

Design and rating comparisons of PWM voltage source rectifiers and active power filters for AC drives with unity power factor

Given terminal constraints of unity power factor in ac drive applications, two ac drives are possible: one with a pulse-width modulation voltage source rectifier (PWM-VSR) and the other using a diode rectifier and an active power filter. Despite numerous publications for the two drives, the features and advantages between them have not been clearly explained. This paper presents a theoretical analysis and systematic comparison between the two drive topologies. Converter kVA ratings, dc-link voltage requirements, switch ratings, semiconductor losses, and reactive component designs are considered for the evaluations.     

A PFC voltage regulator with low input current distortion derived from a rectifierless topology

This paper presents an ac-dc converter topology for realization of power factor correction (PFC) voltage regulators for applications where the mains frequency is high and a low input current harmonic is required, e.g., in aircraft power systems. The proposed converter represents a minimal configuration consisting of two basic converters, which can be systematically derived from a previously proposed general synthesis procedure for rectifierless ac-dc converters. The proposed PFC converter has incorporated a control method which drastically reduces the circulating power and hence raises the efficiency to a level comparable to existing PFC converters. The proposed PFC converter can completely eliminate any crossover distortion, which can be significant for supply systems having a high mains frequency. In addition, the proposed converter allows bidirectional energy flow ensuring all inductors work in continuous conduction mode hence eliminating the distortion due to the abrupt change of dynamic response when the operating mode changes. Analysis and design of the power and control circuits will be given and discussed. An experimental system will be presented for verification purposes.     

An IC medium power voltage regulator

This article describes a monolithic integrated-circuit voltage regulator for use in medium-power applications in the achievement of ``local' or ``on-card' regulation. Included are design features, an explanation of circuit's operation, a dc analysis, regulation analysis, performance characteristics, design rules and considerations, and selected applications.     

VSS control of unity power factor

Three-phase pulsewidth modulation (PWM) converters, specifically, voltage-source inverters (VSI), are possibly the most frequently used power converters for applications such as industrial motor control, robotics, air conditioning and ventilation, uninterruptible power supplies, electric vehicles, etc. With the introduction of standards on limiting harmonic pollution of electrical power distribution systems, three-phase PWM converters are being considered as prime candidates for interfacing high-power electronic equipment to power supply lines. In these applications, converters can provide input currents without distortion and with unity power factor. In this paper, the idea of using variable-structure system (VSS) control strategy of a boost rectifier in sliding mode is described. A new discrete-time control algorithm has been developed by combining VSS and Lyapunov design. It possesses all the good properties of the sliding mode and avoids the unnecessary discontinuity of the central input, thus eliminating chattering, which has been considered a serious obstacle to applications of VSS. A unified control approach for output DC voltage and input AC currents based on discrete-time sliding mode is developed. The reference tracking performance is demonstrated in terms of transient and steady-state characteristics by simulation and experimental results. The invariance and the robustness features of the proposed control method are verified by experiment in the presence of large uncertainty in parameters and external perturbations     

A unity power factor converter using half-bridge boost topology

A single-phase high-efficiency near-unity power-factor (PF) half-bridge boost converter circuit, which has been proposed earlier by other researchers, is presented with detailed analysis. This converter is capable of operating under variable PF. However, the focus of this paper is in achieving unity PF operation only. The efficiency of this circuit is high because there is only one series semiconductor on-state voltage drop at any instant. The existence of an imbalance in the voltages of the two DC-link capacitors, which was noted before, is confirmed here. The cause for the imbalance is analyzed using appropriate models, and a control method to eliminate it is discussed in detail. Analysis and design considerations for the power circuit using the fixed-band hysteresis current control (HCC) technique are provided. The analytical results are verified through simulation using switched and averaged circuit models of the scheme and also through experimental work. At 90-V AC input and 300-W 300-V output, the experimental prototype demonstrates an efficiency of 96.23% and a PF of 0.998. This converter, with its relatively high DC-output voltage, is well suited for the 110-V utility supply system. A circuit modification for universal input voltage range operation is also suggested     

基于Buck—Boost电路的宽输出电压AC—DC电源设计

设计了一种宽输出电压的AC—DC开关电源,其主要特征是输出电压可以在较大范围内任意调节,解决了传统的开关电源只能输出几个特定电压值的问题。该设计的核心是反激变换电路和Buck—Boost电路。分析了这两种电路的工作原理及其应用,并且给出了具体的设计。实验表明,设计的电源能较好地实现了输出电压的宽范围调节。