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%.     

Multiple switching-mode series-resonant half-bridge converter for a wide load range

In this article, a multiple switching-mode series-resonant half-bridge (SRHB) dc–dc converter is presented. The proposed multiple switching scheme changes switching modes to improve power efficiency for a wide output range, especially in the low output power range. This multiple switching scheme is composed of three different switching modes depending on the output power. The prototype was implemented using a single-chip microcontroller. With the multiple switching mode, high efficiency is achieved over an entire output power region. Experimental results on a 1.2?kW prototype are presented to confirm the performance of the proposed multiple switching scheme for an SRHB converter.     

A two-output series-resonant inverter for induction-heating cooking appliances

Multiple-burner induction-heating cooking appliances are suitable for using multiple-output inverters. Some common approaches use several single-output inverters or a single-output inverter multiplexing the loads along the time periodically. By specifying a two-output series-resonant high-frequency inverter, a new inverter is obtained fulfilling the requirements. The synthesized converter can be considered as a two-output extension of a full-bridge topology. It allows the control of the two outputs, simultaneously and independently, up to their rated powers saving component count compared with the two-converter solution and providing a higher utilization of electronics. To verify theoretical predictions, the proposed converter is designed and tested experimentally in an induction-heating appliance prototype. A fixed-frequency control strategy is digitally implemented with good final performances for the application, including ZVS operation for active devices and a quick heating function. Although the work is focused on low-power induction heating, it can be probably useful for other power electronic applications.     

A series-resonant DC/AC inverter for impedance-load drives

A DC/AC inverter without cycloconversion configured by a half-bridge series-resonant inversion (HB-SRI) circuit is presented. The inverter is a series resonator with two auxiliary switches in shunt with the resonant capacitor so as 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 presented HB-SRI is operated by frequency modulation with a constant-on time control. System modeling and waveform syntheses for the output sinusoidal voltage and its current are clearly derived, A typical design example of a 500 W HB-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%     

A study of series-resonant DC/AC inverter

A new DC/AC inversion for achieving an AC sinusoidal waveform synthesized by a series of quasi-sinusoidal pulses is described. A modified pulse-width-modulated (PWM) controller is presented for driving the power switch to operate in a forced discontinuous-conduction mode (FDCM) so as to achieve series-resonance in the power stage. The output power results mainly from the energy stored in the resonant capacitor and is independent of the number of the resonant quasisinusoidal pulses. Three dynamic conversion states including charging, resonant, and RC-discharging states are modeled and analyzed. Signal analysis for the composite AC sinusoidal waveform is conducted. A small-signal model for system performance investigation is described. A prototype of a 1 kW DC/AC inverter is examined by simulation and experimentation in order to assess the system performance     

A 50-150 kHz half-bridge inverter for induction heatingapplications

A half-bridge resonant-type IGBT inverter suitable for heating magnetic and nonmagnetic materials at high-frequency is described. A series-parallel arrangement of capacitors is adopted and an optimum mode of operation is proposed. In this mode, the inverter is operated at unity power factor by PLL control irrespective of load variations, with maximum current gain, maximum overall system efficiency, and practically no voltage spikes in the devices at turn-off. The actual performance was tested on a 50-150 kHz prototype rated at 6 kW. The low-cost developed hybrid inverter is characterized by its simplicity of design and operation, yet is versatile in performance. A simplified analysis and detailed experimental results are presented     

电压源型SVPWM逆变器死区效应补偿方法

针对电压源型SVPWM逆变器的死区效应,详细分析了死区时间对逆变器输出电压的影响,以及零电流箝位现象,提出一种基于空间电压矢量脉宽调制(SVPWM)的死区补偿新算法。该方法在电机定子绕组A相电流过零点处设置夹断区间,采用夹断区间外优化死区设置、按固定值补偿占空比,夹断区间内线性补偿占空比的新方法,来补偿死区效应对逆变器输出的影响。仿真结果表明,设计的死区补偿新算法有效地减小了电流畸变和谐波分量,提高了逆变器的供电效率。     

一种改进的单相逆变器重复控制方案

提出一种新的重复控制方案,通过电容电流内环反馈,消除逆变器固有的谐振峰,简化了重复控制器的设计;改进内模中的Q（z）,采用零相移低通滤波器,提高了系统的稳态精度。Matlab仿真结果表明,该控制方案可以获得高质量的电压输出,在非线性负载条件下THD仅为0.65%,稳态误差只有0.12%。     

Auto-charge pump for half-bridge inverters

The auto-charge pump is a self-starting and self-sustaining circuit used to generate a floating voltage supply for the high side circuitry of half-bridge inverters. The switching output of the half-bridge replaces the dedicated pump oscillator thus simplifying the circuit. A model is derived which is then verified experimentally     

An improved starting strategy for voltage-source inverter fed threephase induction motor drives under inverter fault conditions

Three phase voltage-fed inverter induction motor drives are prone to shoot through and other inverter faults that cause the drive system to shut down. The paper describes a novel strategy for restarting the drive in variable voltage variable frequency single phase mode in the presence of open base drive and shoot through fault in the inverter. The proposed method requires only the motor terminal voltages and currents to be measured. Therefore, it can be applied to even low performance open loop drives with the addition of two motor terminal voltage sensors. The starting algorithm has been verified by computer simulation and experiments on a 1 hp laboratory prototype. Experimental results are in good agreement with simulation predictions. The starting strategy described in this paper is expected to provide an economic alternative to more expensive redundancy techniques which find justification only in a few specialized applications     

两级式并网逆变器分时复合控制策略研究

针对光伏发电系统中的两级式并网逆变器,采用了一种新型的分时复合控制策略。首先详细分析了分时复合控制策略的基本工作原理,该方法可以使得前后两级电路交替进行高频开关工作,从而有利于减小损耗;在此基础上,对分时复合控制策略下的入网电流控制环路进行小信号建模,并给出了相应的控制环路参数设计,以保证具有良好的稳态和动态性能;最后搭建了一台1 k W实验样机并进行实验验证。实验结果表明所采用分时复合控制策略的可行性和有效性。     

Active-clamp snubbers for isolated half-bridge DC-DC converters

In conventional isolated half-bridge dc-dc converters, the leakage-inductance-related losses degrade converter efficiency and limit the ability to increase the converters' switching frequencies. In this paper, a novel active-clamp snubber circuit for half-bridge dc-dc converters is proposed to recycle the energy stored in the leakage inductance by transferring this energy to a capacitor with zero-voltage zero-current-switching switched auxiliary switches, such that body-diode conduction of primary-side main switches are prevented and primary side ringing are attenuated resulting in improved converter efficiency. Principles of operation and simulation analysis are presented and supported by experimental results that show significant improvement in efficiency.     

A three-phase to three-phase series-resonant power converter withoptimal input current waveforms. I. Control strategy

A control strategy for multiphase-input multiphase-output AC to AC series-resonant (SR) power converters is presented. After reviewing some basics in SR power converters, a hierarchy of control mechanisms is presented, together with their respective theoretical backgrounds and practical limitations. The respective controllers are then presented in a simulation context. The control scheme fully exploits the capabilities of high-frequency power converters and facilitates the extraction of currents at a unity power factor from the supply side, even under transient conditions. The control scheme takes into account losses and inaccuracies in the control electronics without deteriorating the intended waveforms. Through computer simulation, it has been shown that, in particular, the input current wave-shapes are greatly improved compared to the best-available operating data     

A new optimized space-vector modulation strategy for acomponent-minimized voltage source inverter

This paper presents a new space-vector modulation strategy suitable for a low-cost pulse-width-modulation (PWM) voltage-source (VS) inverter employing only four switches, four diodes, and a split-capacitor bank in the DC link. The work is motivated by the need for an efficient and flexible modulation method, which is optimized with respect to minimum machine-torque ripple. The modulation strategy is named space-vector modulation for four-switch inverter (SVMFSI), and it is realized by planning the switching patterns between four active voltage vectors on the basis of a desired flux trajectory for the stator-flux vector in the AC machine. The strategy is implemented in a single 8-bit microcontroller as a double-sided modulation strategy. Simulations of the machine-torque ripple are performed at a switching frequency of 4 kHz and indicate a torque ripple of 14% at nominal load. Finally, selected results are verified experimentally on a 1.5-kVA prototype B4 inverter. The test results indicate high-quality output-voltage spectra with no low-order voltage harmonics and a harmonic-loss factor (HLF) of 1.12% at unity modulation index     

Starting control for series-resonant electronic ballast withrapid-start fluorescent lamp

A starting-aid circuit is added to the series-resonant electronic ballast for reducing the glow current in a rapid-start fluorescent lamp during the preheating. By controlling the operating frequency, the electronic ballast provides an adequate filament current for preheating with nearly zero lamp voltage     

小型光伏逆变器双闭环控制策略研究

文中提出了一种改进的单相光伏并网逆变器双闭环控制策略,电压外环采用准PR调节可以实现对参考电压的无静差跟踪,抑制了电网频率波动对系统的影响,提高了系统的抗干扰能力。电容电流作为电流内环控制量改善了系统的动态响应性能以及带负载能力。建立了系统控制结构模型并进行了参数设计,最后通过仿真验证了所提理论的正确性和有效性。     

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.     

Improved control strategy on single-phase current-fed interactive inverter

The single-phase PWM current-fed inverter has some feasible advantages for utility-interactive systems. In particular, it is more suitable for the non-isolated type of utility-interactive system topology that is widely used for residential photovoltaic power generation systems in Japan. But, this sort of inverter has a significant disadvantage. The output current of the inverter includes large harmonic components when its smoothing reactor is not large enough to eliminate its current ripple component. This paper presents a new control strategy to reduce sufficiently the harmonic component of the single-phase current-fed PWM inverter, even when the ripple current in the smoothing reactor is large. The principle of the proposed control strategy for this inverter system is described and its simulation results are evaluated.     

An adaptive dead-time compensation strategy for voltage source inverter fed motor drives

This paper presents an adaptive dead-time compensation strategy to obtain fundamental phase voltage for inverter fed vector controlled permanent magnet synchronous motor drives. The amplitude of phase dead-time compensation voltage (DTCV) to compensate disturbance voltage due to undesirable characteristics of inverter, such as dead-time, turn-on/off time of switching devices, and on-voltages of switching devices and diodes is adaptively determined according to a dead-time compensation time (DTCT). DTCT is identified on-line with using a /spl delta/-axis disturbance voltage in the current reference frame that is synchronized with current vector. The /spl delta/-axis disturbance voltage is estimated by a disturbance observer. The accuracy of identified DTCT is experimentally confirmed by calculating the mean absolute percentage error (MAPE) between a calculated active power and a measured one. MAPE for adaptive DTCT is almost within 5% at any operating point.