The three-phase resonant DC link inverter with soft-switching function

ABSTRACT

In order to realise the energy-saving operation of the three-phase inverter, a three-phase resonant DC link inverter with soft-switching function is proposed. The auxiliary resonant circuit on the DC side participates in the commutation process, so that the DC link voltage can change to zero before the main switch on the bridge arm is switched. Therefore, the main switch can complete the zero-voltage soft-switching and realise the energy-saving operation of the inverter by reducing the switching power loss. The circuit workflow and parameter design rules in each switching period are analysed. As indicated from the experimental results, the switching device is in the soft-switching state when it is switched, and when the output power reaches the rated value of 2.5 kW, the efficiency of the prototype is 98.4%, which is higher than that of the same type of soft-switching inverters. Thus, the auxiliary resonant circuit structure has reference value for the research and development of energy-saving three-phase inverters.     

Resonant DC link soft-switching inverter with low-loss auxiliary circuit

An auxiliary switching device is usually set on the DC bus of the resonant DC link inverter, which restricts the efficiency of the inverter and is also one of the reasons for its not extensive application and promotion in the high-power field. To solve the problem, auxiliary circuits and DC bus of the resonant DC link soft-switching inverter designed in this paper are connected in parallel, and auxiliary switching devices and resonant elements are not connected in series on the DC bus, which help to improve the efficiency and reduce the power losses of the auxiliary resonant circuits. Based on the equivalent circuits in different operating modes, the paper analyzes the working process of the soft-switching inverter, soft-switching realization conditions and design rules. A 10 kW laboratory prototype is built, and through the comparison of the experimental results from it and the hard-switching inverter, it is shown that the efficiency improvement value of the designed inverter at full load is higher than that at light load. Therefore, the soft-switching inverter designed in this paper is conductive to reducing the power losses of the auxiliary resonant circuits and ensuring the efficient use of the electric energy.     

三电平逆变器硬件电路及其仿真结果的研究

主要介绍了一种三电平逆变器的硬件电路设计,用MATLAB对设计其进行了仿真并得出仿真结果同时也给出了在硬件平台上的实验结果,最终证明逆变器可以被广泛应用于大功率场合.     

节能型谐振直流环节逆变器

为改善逆变器的运行效率,提出了一种节能型三相谐振直流环节软开关逆变电路,在直流环节增设了辅助电路.当主开关需要切换时,提前使辅助电路进入谐振状态,将直流环节电压变化到零,保证主开关完成零电压软切换,并且辅助开关也能完成软切换.通过控制辅助开关切换的间隔时间来调节直流环节电压保持为零的时间,使逆变器能根据需要来调整脉宽调制策略.详细说明了电路的工作过程.实验结果表明逆变器主开关和辅助开关能完成软切换.因此,该拓扑结构对于研发高性能谐振直流环节逆变器具有借鉴意义.     

A new quasi-parallel resonant DC link for soft-switching PWMinverters

A new quasi-parallel resonant DC-link inverter with the more flexible pulse-width-modulation (PWM) capability and easier control is proposed in this paper. With the addition of one coupling core and one diode, the circuit can be directly applied to the single/three-phase inverter to achieve the soft-switching action. For the proposed topology, it needs neither the help of the inverter switch devices nor the requirement of voltage/current sensors. Random duration of the zero DC-link voltage can be obtained, and the voltage stresses of the inverter switches can be maintained to the minimum. The relative analysis of the presented circuit has been performed and verified by the experiment     

Quasi-parallel resonant DC link inverter with improved PWMcapability

A quasi-parallel resonant DC-link (QPRDCL) circuit with improved PWM capability is proposed for the zero voltage switching (ZVS) three phase PWM inverter. The circuit has minimum voltage stresses and improved PWM capability due to the flexible selectability of the on/off instants of the resonant link     

一种优化三电平逆变器的SVPWM算法的研究

针对传统SVPWM算法计算复杂的缺点,提出一种基于60°坐标下三电平逆变器SVPWM调制算法的控制策略。该控制策略可大幅简化传统SVPWM算法参考矢量扇区判定及开关矢量作用时间的运算,通过在g-h非正交坐标系内对大小扇区规则判断、基本矢量作用时间计算和作用顺序方法进行了研究,减小了控制器的计算工作量。采用Matlab/Simulink仿真软件对该控制策略进行了仿真,仿真结果验证了该控制策略的正确性及有效性。     

Novel switching method for single-phase NPC three-level inverter with neutral-point voltage control

This paper proposes a novel switching method with the neutral-point voltage control in a single-phase neutral-point-clamped three-level inverter (SP-NPCI) used in photovoltaic systems. A proposed novel switching method for the SP-NPCI improves the efficiency. The main concept is to fix the switching state of one leg. As a result, the switching loss decreases and the total efficiency is improved. In addition, it enables the maximum power-point-tracking operation to be performed by applying the proposed neutral-point voltage control algorithm. This control is implemented by modifying the reference signal. Simulation and experimental results provide verification of the performance of a novel switching method with the neutral-point voltage control.     

具有提升直流环节稳态电压功能的单相全桥 谐振直流环节逆变器

为改善直流电压利用率,提出了一种具有提升直流环节稳态电压功能的单相全桥谐振直流环节软开关逆变器,利用辅助电路中的变压器可以将电能补充到直流母线上等效为电压源的钳位电容,使直流环节稳态电压高于直流电源电压,提高了逆变器输出线电压的基波幅值和直流电压利用率.文中分析了电路的工作状态.在4kW样机上的实验结果表明逆变器的主开关和辅助开关能完成软切换.因此,该拓扑结构对于研发高性能谐振直流环节逆变器具有一定的借鉴意义.     

新型单相全桥谐振直流环节逆变器

为改善单相全桥逆变器的性能,提出了一种新型单相全桥谐振直流环节逆变器.位于直流环节的辅助电路能提升直流母线电压稳态值,减少直流母线电压的零状态对直流电压利用率的负面影响.文中分析了逆变器的换流过程.实验结果表明开关器件完成了软切换,逆变器性能得到了改善.     

灵活直流环节型全软开关逆变器

本文提出了灵活直流环节型全软开关逆变器.其主要贡献如下:(1)给出了以Buck电路为直流环节的全软开关逆变器;(2)给出了最小电压、电流应力的全软开关Buck型DC-DC变换器的理论分析;(3)给出了这种逆变器的控制策略.仿真结果和实验结果(2.7kW)证明了这个电路优于谐振型直流环节型逆变器.     

A novel current initialization scheme for parallel resonant dc link inverter

In this paper a novel current initialization scheme is proposed for a parallel resonant dc link inverter. The method of current initialization is based on the state transition analysis of the system as a boundary-value problem. It is shown that, for a given load current, it is possible to force the dc link voltage to go to zero at a prescribed time by properly choosing the initial dc link current. This technique makes it possible to operate the resonant dc link inverter without any zero-crossing failure, which is the most important issue for satisfactory operation of such an inverter. The proposed current initialization technique is validated through digital computer simulation studies and practical implementation results.     

一种新型高电压ZVZCS三电平DC/DC变换器的研究

介绍一种适用于高电压场合的新型ZVZCS三电平DC／DC变换器，详细分析了电路的工作原理。设计实例和仿真结果验证了理论分析的正确性。     

基于DSP的三相并联直流谐振开关逆变器研究

阐述了一种三相并联直流谐振开关逆变拓扑电路的工作原理,针对该系统控制电路的特点,应用DSP实现了数字化实时控制。并搭建了硬件实验平台,给出了软件设计流程。实验结果证明了该系统具有良好的性能。     

基于Quasi-Z源变换器的无刷直流电机控制系统研究

为了克服传统电动汽车功率变换器两级结构的不足,进一步提高其效率,提出一种基于Quasi-Z源变换器的无刷直流电机控制系统。分析其基本原理,利用该技术实现直流母线升压与电机调速一体化控制,使传统两级结构转变为一级结构。采用Simulink对控制系统进行仿真,验证此种控制方法的可行性。     

一种宽输入电压范围软开关电流型DC/DC转换器

针对太阳能光伏及燃料电池等领域电源需要较宽输入电压范围的需求,提出一种通用的具有较宽输入电压范围的软开关电流型DC/DC转换器。该转换器采用了固定频率混合调制设计,可以在所有工作条件下实现半导体器件的软开关工作,并采用电流馈电技术以便适用于低电压高电流的电源。相较于传统转换器,该转换器更为通用,能够实现零电压开关和零电流开关,并且能够在输入电压和负载变化出现较大变化时控制输出电压。实验结果显示,在20-60V输入电压范围内且负载出现变化时,该转换器均表现出良好的性能。     

基于DC/DC变换的逆变技术的研究

传统逆变器结构简单、技术成熟,但由于自身拓扑结构的不足使其存在开关损耗大、输出滤波要求高、输出交流幅值受电源电压限制、开关状态转换时可能出现直通短路等缺点。基于Buck的DC/DC变换器由于本身拓扑结构的优势,有效避免了传统逆变器的这些问题,进一步提高了效率。简要介绍了现有基于DC/DC变换器的逆变电路拓扑,并分析了各自拓扑结构的优缺点及相应的控制方式。     

单相光伏并网逆变器直流注入问题的成因和抑制

随着非隔离型光伏并网逆变器的广泛应用,直流注入问题也日益受到重视,IEEE Std 929-2000规定直流注入必须小于系统额定电流的0.5%。将直流注入产生的原因分为两种类型:测量器件输入失调导致的平移型直流注入和测量器件的非线性造成的非线性直流注入,并分别提出了应对方法。针对平移型的直流注入问题,提出了通过一个直流分量积分补偿环节来抑制逆变器控制算法中偏移型直流分量,该直流抑制算法无需增加外围硬件电路,且只占用很少的控制芯片资源。针对非线性直流注入问题,做出了定量分析,为测量元器件非线性度指标的选择提供了的参考价值。最后将上述直流抑制算法应用于无差拍并网控制中,并在Matlab/Simulink进行了仿真分析,结果验证了理论分析和算法的正确性。     

一族新颖的全桥/半桥组合DC/DC拓扑

介绍了一族全桥/半桥组合DC/DC变换器的拓扑结构,并以其中一种为例分析了其工作原理,最后通过仿真和试验验证了该族变换器具有高效率、高功率密度、低电磁干扰,在全负载范围内实现软开关,及较好的动态特性等优点。