A novel single-stage full-bridge buck-boost inverter

A novel single-stage full-bridge series-resonant buck-boost inverter (FB-SRBBI) is proposed in this paper. The proposed inverter only includes a full-bridge topology and a LC resonant tank without auxiliary switches. The output voltage of the proposed inverter can be larger or lower than the dc input voltage, depending on the instantaneous duty-cycle. This property is not found in the classical voltage source inverter, which produces an ac output instantaneous voltage always lower than the dc input voltage. The proposed inverter circuit topology provides the main switch for turn-on at ZCS by a resonant tank. The nonlinear control strategy is designed against the input dc perturbation and achieves well dynamic regulation. An average approach is employed to analyze the system. A design example of 500 W dc/ac inverter is examined to assess the inverter performance and it provides high power efficiency above 90% under the rated power.     

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 Novel Single-Stage Series-Resonant Buck–Boost Inverter

A novel single-stage series-resonant buck–boost inverter (SRBBI) is proposed in this paper. The main attribute of the novel inverter topology is the fact that it generates an ac output voltage larger or lower than the dc input one, depending on the instantaneous duty cycle. This property is not found in the classical voltage-source inverter, which produces an ac output instantaneous voltage which always lower than the dc input voltage. The state-space averaging approach is used to estimate and examine the steady-state and dynamic character of the new single-stage SRBBI. The principle of operation, theoretical analysis, and experimental results of the proposed inverter, rated 500 W and operating at 40 kHz, are provided in this paper to verify the performance of the SRBBI.     

基于Buck-Boost逆变器的离散滑模控制仿真研究

为了获得比较理想的正弦输出电压，优化逆变器的动态性能，文中基于Buck—Boost逆变器．采用了离散滑模变结构的控制策略。Buck—Boost逆变器可以获得比直流输入电源高或低的交流输出电压，文中阐述了其工作原理．并结合状态方程，推导出滑模面的存在条件、到达条件和稳定条件，然后对电路参数、控制系数以及控制算法进行了设计。仿真结果表明采用离散滑模控制的Buck—Boost逆变器对系统扰动和负载变化具有很强的鲁棒性，系统具有良好的动态响应。     

Parallel processing inverter system

A novel method of instantaneous voltage and power balance control of a parallel processing inverter system is proposed. It consists of a high-speed switching PWM (pulsewidth modulated) inverter with an instantaneous current minor loop controller, a voltage major loop controller, and a power balance controller. This system realizes the following functions with only one inverter: constant AC output voltage control with reactive power control, active filtering to absorb load current harmonics, DC voltage and current control as AC-to-DC converter, and uninterruptible power supply (UPS) for stand-alone operation. This system covers a wide application range, including UPS systems, new energy systems, and active filters with voltage control functions     

Linearly controllable boost voltages from Tri-Level PWMcurrent-source inverter

The peak line-to-line inverter AC voltage, in general, cannot exceed the supply DC voltage and transformers have to be used when voltage step-up is required. This paper describes how the necessity of using a Tri-Level PWM strategy in the current source inverter can be turned into an advantage by producing a voltage boost so that transformers are no longer required. During the frequent occurrence of the “shoot-through” states, which is the characteristic of the Tri-Level PWM-controlled inverter, magnetic energy builds up in the DC link inductor. At the end of these periods, the L_dcdI_dc/dt voltage across the inductor augments the inverter output voltage in the same way as in the basic boost type DC/DC power converter. The paper describes the circuitry required to ensure linear control. Analytical, simulation, and experimental results are given. Applications are found in all instances where the AC voltage is higher than the available supply DC voltage     

Single-stage three-phase buck-boost type AC-DC converter with highpower factor

A new control process for single-stage three-phase buck-boost type AC-DC power converters with high power factor, sinusoidal input currents and adjustable output voltage is proposed. This converter allows variable power factor operation, but this work focus on achieving unity power factor. The proposed control method includes a fast and robust input current controller based on a vectorial sliding mode approach. The active nonlinear control strategy applied to this power converter, allows high quality input currents. Given the comparatively slow dynamics of the DC output voltage, a proportional integral (PI) controller is adopted to regulate the converter output voltage. The voltage controller modulates the amplitudes of the current references, which are sinusoidal and synchronous with the input source voltages. Experimental results from a laboratory prototype show the high power factor and the low harmonic distortion characteristics of the circuit     

New three-port DC-AC inverter outputting a single-phase and a set of three-phase AC voltages

A conventional DC-AC inverter can only output either a single-phase AC voltage or a set of three-phase AC voltages. A new three-port DC-AC inverter which can simultaneously output a single-phase AC voltage and a set of three-phase AC voltages is proposed in this paper. This three-port DC-AC inverter is based on the three-port T-type multi-level power converter which is composed of three T-type power electronic legs, a decoupling transformer set, a filter inductor set, a single-phase filter capacitor, and a three-phase filter capacitor set. The DC port of the proposed power converter is connected to a DC power source to act as the input port, and the single-phase AC port and the three-phase AC port serve as two output ports to supply power to the single-phase load and the three-phase load, respectively. The zero-sequence transformer is used to decouple the single-phase and three-phase AC components, which are generated by the three T-type power electronic legs. The operation principle of this three-port DC-AC inverter is analyzed, and a hardware prototype is established to verify the performance of the proposed three-port DC-AC inverter. The experimental results are as expected.     

基于一种新型电路拓扑的UPS设菅

文中介绍了一种应用于UPS的新型双Boost电路拓扑,可以实现DC／AC单级升压变换。在对主电路拓扑和工作原理进行分析的基础上,采用SPWM调制方法对其进行了软件仿真和硬件实验。实验结果证明,以Boost变换电路可以实现高频功率变换情况下的单级升压逆变输出。     

Boost DC-AC inverter: a new control strategy

Boost dc-ac inverter naturally generates in a single stage an ac voltage whose peak value can be lower or greater than the dc input voltage. The main drawback of this structure deals with its control. Boost inverter consists of Boost dc-dc converters that have to be controlled in a variable-operation point condition. The sliding mode control has been proposed as an option. However, it does not directly control the inductance averaged-current. This paper proposes a control strategy for the Boost inverter in which each Boost is controlled by means of a double-loop regulation scheme that consists of a new inductor current control inner loop and an also new output voltage control outer loop. These loops include compensations in order to cope with the Boost variable operation point condition and to achieve a high robustness to both input voltage and output current disturbances. As shown by simulation and prototype experimental results, the proposed control strategy achieves a very high reliable performance, even in difficult transient situations such as nonlinear loads, abrupt load changes, short circuits, etc., which sliding mode control cannot cope with.     

Design and analysis of power-CMOS-gate-based switched-capacitor boost DC-AC inverter

A multistage power CMOS-transmission-gate-based (CMOS-TG) quasi-switched-capacitor (QSC) boost DC-AC inverter is proposed and integrated with a boost DC-DC converter for a step-up application with AC or DC load. In this paper, using CMOS-TG as a bidirectional switch, the various topologies can be integrated in the same configuration for achieving two functions: boosting and alternating; boosting for getting a sinusoidal output in which the peak is the result of a many times step-up of the input; alternating to realize the positive/negative half sinusoidal of the output. The inverter does not require any inductive elements as inductor and transformer, so integrated circuit (IC) fabrication will be promising for realization. By using the state-space averaging technique, the large-signal state-space model of the inverter is proposed, and then both the static analysis and dynamic small-signal analysis are derived to form a unified formulation for inverter/converter. Based on this formulation, there are presented for theoretical analysis/control design, including steady-state power, conversion efficiency, voltage conversion ratio, output ripple percentage, capacitance selection, closed-loop control and stability, and total harmonic distortion (THD), etc. Finally, a six-stage QSC boost DC-AC inverter is simulated by PSPICE, and the simulations are discussed for some cases, including: 1) steady-state AC output, ripple percentage, and power efficiency; 2) transient response of the regulated inverter for load variation; 3) a practical capacitive load: electromagnetic luminescent (EL) lamp, and 4) efficiency, ripple percentage, and THD for different loads. The results are illustrated to show the efficacy of the proposed inverter.     

Nonlinear-controlled strategy for soft-switched series-resonant DC/AC inverter without auxiliary switches

A nonlinear control for soft-switched series-resonant DC/AC inverter without auxiliary switches is presented. The inverter is configured by a full-bridge series-resonant inversion (FB-SRI) without cycloconversion and auxiliary switches. The inverter is a series resonator with four main switches to configure adaptively the output current suitable for impedance load. The output sinusoidal voltage is synthesized by a series of equal-amplitude quasisinusoidal pulses (QSPs) and the corresponding current is formed by unequal QSPs and adaptively phase-shifts to the impedance load. The nonlinear control strategy is designed against the input DC perturbation and achieves good dynamic regulation. The presented FB-SRI is operated by frequency modulation with a constant-on time control. Waveform syntheses for the output sinusoidal voltage and its current are clearly derived. A typical design example of a 500W FB-SRI inverter is examined to assess the system performance. The power efficiency is over 90% when the inverter output is above 200 W. The total harmonic distortions (THDs) for various impedance loads are all within 6%.     

An accurate approach of nonlinearity compensation for VSI inverter output voltage

An accurate nonlinearity compensation technique for voltage source inverter (VSI) inverters is presented in this paper. Because of the nonlinearity introduced by the dead time, turn-on/off delay, snubber circuit and voltage drop across power devices, the output voltage of VSI inverters is distorted seriously in the low output voltage region. This distortion influences the output torque of IM motors for constant V/f drives. The nonlinearity of the inverter also causes 5th and 7th harmonic distortion in the line current when the distributed energy system operates in the grid-connected mode, i.e., when the distributed energy system is parallel to a large power system through the VSI inverter. Therefore, the exact compensation of this nonlinearity in the VSI inverter over the entire range of output voltage is desirable. In this paper, the nonlinearity of VSI inverter output voltage and the harmonic distortion in the line current are analyzed based on an open-loop system and a L-R load. By minimizing the harmonic component of the current in a d-axis and q-axis synchronous rotating reference frame, the exact compensation factor was obtained. Simulations and experimental results in the low frequency and low output voltage region are presented.     

大功率车载交流电源的设计与研究

针对解决载有交流电动机的电动车车载电源的直交流电压转换问题,本论文在分析了逆变器结构和原理的基础上,提出了DC-DC-AC的设计思路,采用高频变压器、PWM和SPWM技术搭载控制电路,将车载48 V铅酸电池电压升压,再经过逆变,得到纯正弦交流电压;同时本论文给出了高频变压器和滤波电路的参数选定方法。最后实验结果表明48 V铅酸电池经过升压和逆变,可输出频率为50 Hz,幅值为220 V的纯正弦交流电压;同时实物电路具有体积小、设计成本低、输出交流电压稳定、带载能力强的良好性能。     

基于风力发电系统的电能变换装置研究

针对目前独立运行风力发电系统通过＂交流-直流-交流＂的转换方式供电时,存在能量利用率偏低,且往往达不到负载需求电能的缺点,采用了DC/DC升压及DC/AC逆变技术在风力发电能量转换体系中,设计了一种新型的能量供应体系及其控制策略,并在此基础上应用Matlab/Simulink搭建了仿真程序。通过仿真,得到了用户需要的稳定交流电能,验证了控制策略的正确性及控制方案的可行性,具有很好的推广应用价值和进一步的研究价值。     

Solar power generation system for reducing leakage current

This paper proposes a transformer-less multi-level solar power generation system. This solar power generation system is composed of a solar cell array, a boost power converter, an isolation switch set and a full-bridge inverter. A unipolar pulse-width modulation (PWM) strategy is used in the full-bridge inverter to attenuate the output ripple current. Circuit isolation is accomplished by integrating the isolation switch set between the solar cell array and the utility, to suppress the leakage current. The isolation switch set also determines the DC bus voltage for the full-bridge inverter connecting to the solar cell array or the output of the boost power converter. Accordingly, the proposed transformer-less multi-level solar power generation system generates a five-level voltage, and the partial power of the solar cell array is also converted to AC power using only the full-bridge inverter, so the power efficiency is increased. A prototype is developed to validate the performance of the proposed transformer-less multi-level solar power generation system.     

Reversible unity power factor step-up/step-down AC-DC convertercontrolled by sliding mode

A reversible step-up/step-down AC-DC converter is presented in this paper. It is a fifth-order system, capable of managing power transfer from a DC source to an AC one, with any ratio between the DC and the AC voltage levels, and producing a sinusoidal output current, using only one power processing stage. By reversing the energy flow this circuit becomes a high power factor rectifier. This reversion can be obtained simply by inverting the reference AC current. The system is analyzed as the connection of two independent lower order subsystems, controlled by sliding mode with decentralised switching scheme. Experimental results from a 100 W prototype operating in both senses, as inverter and as rectifier, are shown to confirm the mathematical analyses and simulations     

基于有源功率因数校正的高功率因数电源设计

构建有源功率因数校正（APFC）的高功率因数直流电源。该系统采用TI公司专用APFC整流控制芯片UCC28019作为控制核心,构成电压外环和电流内环的双环控制。其中内环电流环作用是使网侧交流输入电流跟踪电网电压的波形与相位;外环电压环为输出直流电压控制环。外环电压调节器的输出控制内环电流调节器的增益,使输出直流电压稳定。系统采用ATmega16单片机进行监控,完成输出电压的可调以及输入功率因数、输出电压、输出电流等的实时测量与显示和输出过流保护等功能。实测表明,系统性能指标完全达到或超过设计要求。     

Characteristics of load resonant converters operated in ahigh-power factor mode

The performance of the parallel resonant power converter and the combination series/parallel resonant power converter (LCC converter) when operated above resonance in a high power factor mode are determined and compared for single phase applications. When the DC voltage applied to the input of these converters is obtained from a single phase rectifier with a small DC link capacitor, a relatively high power factor inherently results, even with no active control of the input line current. This behavior is due to the pulsating nature of the DC link and the inherent capability of the converters to boost voltage during the valleys of the input AC wave. With no active control of the input line current, the power factor depends on the ratio of operating frequency to tank resonant frequency. With active control of the input line current, near-unity power factor and low-input harmonic currents can be obtained     

DSP-based control of a high frequency three cell flying capacitor inverter

The design, instrumentation and early operation results of a digitally controlled voltage source inverter (VSI) are described. This inverter has been structured from a three cell flying capacitor inverter (TCFCI). Two different inverter control modes – open-loop and closed-loop – are applied by a digital system based on a Texas Instrument TMS320C6713 digital signal processor (DSP) board. The VSI is able to generate AC voltage signals up to 120 V amplitudes at a maximal 6 A current, from ～9 kHz to ～60 kHz in ～900 Hz steps in both controls by varying the signal period through the square-wave command strategy. The multi-cell structure of the inverter provides an output frequency nearly three times that of the TCFCI semiconductor commutation. The power output of the TCFCI can drive a high frequency step-up transformer which, in turn, is associated with a cylindrical reactor where dielectric barrier discharges (DBD) are conducted.