Novel multilevel inverter carrier-based PWM method

The advent of the transformerless multilevel inverter topology has brought forth various pulsewidth modulation (PWM) schemes as a means to control the switching of the active devices in each of the multiple voltage levels in the inverter. An analysis of how existing multilevel carrier-based PWM affects switch utilization for the different levels of a diode-clamped inverter is conducted. Two novel carrier-based multilevel PWM schemes are presented which help to optimize or balance the switch utilization in multilevel inverters. A 10 kW prototype six-level diode-clamped inverter has been built and controlled with the novel PWM strategies proposed in this paper to act as a voltage-source inverter for a motor drive     

一种适用于飞跨电容型多电平逆变器的新型载波同相层叠PWM方法

传统载波层叠PWM方法不能平衡飞跨电容电压,因此不能直接应用于飞跨电容型多电平逆变器。对传统载波同相层叠PWM方法进行改进,增加了零电平选择环节,根据设定值,合理分配零电平向量,从而在设定周期内,平衡飞跨电容电压。该方法随着调制度的不同,载波波形会发生变化,和传统载波移相PWM方法相比,线电压谐波性能也得到了很大提高,尤其是在中等调制度下,效果显著。采用该方法对飞跨电容型三电平逆变器进行了仿真验证,结果证明了该方法的正确性与可行性。     

混合H桥级联型多电平逆变器调制策略优化控制

为提高混合H桥级联型多电平逆变器的运行性能.提出了一种新型锯齿载波交错相移混合调制策略.该调制策略把复杂的混合拓扑"化归"到已有调制策略的拓扑.再利用重构的调制波进行调制.该策略充分利用调制渡的自由度,在三相正弦波中注入特定的混合分量进行优化控制,使得相电压在1/3基波周期内不进行PWM调制,并能保证输出线电压质量.所提出的优化控制方法能提高15.5%直流电压利用率.还能减少1/3高频功率开关的开关次数,优化了逆变系统的运行性能.实验结果验证了提出方法的可行性和有效性.     

一种基于新型载波同相层叠PWM方法的飞跨电容型光伏发电并网技术

针对飞跨电容型三电平光伏逆变器载波移相算法线电压谐波较高,无法灵活控制飞跨电容电压等问题,提出一种基于新型载波同相层叠PWM方法的飞跨电容型光伏发电并网方案。通过增加零电平向量分配环节,平衡飞跨电容电压,降低光伏逆变器线电压谐波。阐述了新型载波同相层叠算法基本原理,分析了该方案降低光伏逆变器线电压THD的优点。通过Matlab/Simulink数字仿真和实验样机,验证了基于新型载波同相层叠方法的飞跨电容型光伏发电并网系统能够有效跟踪最大输出功率,保证直流电压稳定,降低光伏系统输出线电压谐波。     

一种基于新型载波同相层叠PWM方法的飞跨电容型 光伏发电并网技术

针对飞跨电容型三电平光伏逆变器载波移相算法线电压谐波较高,无法灵活控制飞跨电容电压等问题,提出一种基于新型载波同相层叠PWM方法的飞跨电容型光伏发电并网方案。通过增加零电平向量分配环节,平衡飞跨电容电压,降低光伏逆变器线电压谐波。阐述了新型载波同相层叠算法基本原理,分析了该方案降低光伏逆变器线电压THD的优点。通过Matlab/Simulink数字仿真和实验样机,验证了基于新型载波同相层叠方法的飞跨电容型光伏发电并网系统能够有效跟踪最大输出功率,保证直流电压稳定,降低光伏系统输出线电压谐波。     

A large-capacity GTO inverter with low-loss snubber circuits

A large-capacity inverter using high-power gate turn-off (GTO) thyristors that can be used instead of a cycloconverter in AC drives is presented. With the techniques of multiple configuration and GTO series connection, the inverter capacity is increased effectively. High conversion efficiency is obtained by using low-loss snubber circuits for GTOs. It is confirmed that the low-loss snubber circuits using energy recovery units (ERUs) have good performance in pulse-width modulated (PWM) operation. High-energy recovery efficiency is obtained, especially in leading operation (turn-on operation when freewheeling diodes conduct). These snubber circuits have superior ability for clamping overvoltage at GTO turn-off. A 2750 kVA inverter with low-loss snubber circuits using high-power GTOs has been fabricated and evaluated     

单元串联变频器IGBT故障诊断方法

针对单元串联多电平高压变频器的IGBT(绝缘栅双极型晶体管)故障检测问题,基于镜像电流源原理,搭建通过功率单元直流母线电压控制的逆变桥臂输出电压逻辑检测电路,并给出功率单元输出逻辑与驱动信号逻辑的关系,通过动态判别逻辑关系的正确性,诊断出IGBT的故障状态。实验结果表明,该方法诊断迅速,能够在10μs以内正确检测出功率管的故障状态,相比基于各种算法的故障诊断方法,该方法可靠实用,对单元串联型多电平高压变频器的故障诊断具有工程应用价值。     

基于等效电路模型的新型三电平逆变器载波调制方法的研究

提出了一种新型的基于三角载波水平移相的三电平逆变器PWM调制方法。通过分析三电平电压型逆变器主电路结构,建立了相应的等效模型,给出了一种提高等效开关频率的具有二重化特点的载波水平移相调制算法。该调制方法与三电平逆变器空间矢量方法相比,其具有计算简单、实现简单等优点,与一般载波垂直移相调制算法相比,其具有低次谐波小、等效开关频率提高一倍、容易滤波等优点。通过仿真研究,验证了该调制方法的可行性。通过建立等效模型为采用两电平三相逆变器各种调制算法来实现三电平逆变器的控制奠定了研究基础。     

A new regenerative snubber circuit for large-capacity three-level GTO inverter systems

Increase in the capacity of GTOs has made remarkable progress in recent years. At present, 4.5-kV, 4.0-kA GTOs are commercially available, and 6.0-kV, 6.0-kA GTOs made from 6-inch silicon wafers are appearing. The 6-inch GTOs will be applied to our three-level GTO inverter system. In order to apply GTOs to voltage-source inverters, snubber circuits are necessary for limiting on the turn-on di/dt and turn-off dv/dt. To realize high efficiency of the system, regenerative snubber circuits are often applied. A conventional circuit applied to three-level GTO inverters had the problem of long paths created for snubber circuits of the inner GTOs. Another circuit using a current transformer for recovering the energy trapped in the snubber circuits of the inner GTOs has been presented. In this paper, a new regenerative snubber circuit is proposed, which is more suitable for three-level GTO inverter systems with many phase-legs. By applying the snubber circuit, all snubber energy generated by each GTO switching can be regenerated to the dc link. In addition, high current turn-off performance of both the inner and the outer GTOs is verified by several successful experimental results using 6-inch 6.0-kV, 6.0-kA GTOs. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(2): 41–48, 1997     

一种低速下磁链观测补偿的新方法

在电压模型磁链观测中,常用一阶惯性环节代替纯积分环节,解决直流偏置和初始值等问题。但低速时在磁链观测上的误差,会直接影响直接转矩控制系统的效率和性能。本文从理论上和仿真上对低速下的磁链和转矩的观测误差进行了分析,提出了一种新型的在低速下采用电压模型观测异步电机定子磁链的补偿方法。该方法采用检测电机定子电流在低速下对滤波器截止频率进行动态调整的补偿方法,给出了原理框图和实现方法。在数字控制系统中,该补偿方法具有简单、容易实现的优点。并对补偿前后的观测结果进行了仿真比较和试验。仿真和试验结果表明经补偿后直接转矩控制系统的低速性能有十分明显的提高,从而证实了该补偿方法的有效性。     

一种光伏发电用高增益多电平逆变器

针对传统的多电平逆变器存在有源器件数量较多、电容电压不平衡、结构复杂以及电压增益低的问题,提出一种降低器件数量且可扩展的多电平逆变器。该逆变器由开关电容单元和两个半桥组成,使用1个直流电源、3个电容、13个开关管,实现4倍电压增益和九电平交流输出电压。该逆变器通过2个半桥代替后端H桥转换输出电压极性,可以有效降低开关管总电压应力。在所提逆变器的扩展结构中,电容逐级充电的工作方式进一步提高了电压增益和输出电平数。首先,详细阐述了所提逆变器的工作模式、调制策略、电容分析、电压应力计算和电路参数设计。然后,与其他类似多电平逆变器进行了比较。最后,通过仿真与实验验证了所提逆变器的可行性和理论分析的正确性。     

三电平逆变器的空间矢量脉宽调制方法

介绍了三电平逆变器的一种空间矢量脉宽调制方法。仿真结果证明了这种空间矢量脉宽调制方法的有效性。     

一种新颖的含有谐振控制器的CVCF逆变器多环反馈控制方法

多环反馈控制方法以其设计实现过程简单、优越的动态性能而受到特别的关注.它一般包括一个电压外环与一个电流内环,电流内环的给定由电压外环给出.传统多环反馈控制每一环路中使用的都是PID控制器,在稳态精度方面存在缺陷.本文将谐振控制器引入到这种逆变器的多环反馈控制方法中,在电压环控制器中加入了谐振控制器.与传统使用PID控制器的多环反馈控制方法比较,含有谐振控制器的多环反馈控制能获得更高的稳态精度,并且它具有设计简单、易于实现的优点.将含有谐振控制器的多环反馈控制方法用于CVCF(恒压恒频)逆变器,实验结果证明了这种控制方法的有效性.     

二极管钳位型级联多电平逆变器新型SPWM研究

针对目前级联型多电平逆变器正弦脉冲宽度调制(sinusoidal pulse width modulation,SPWM)数字化实现问题,分析常规载波调制SPWM算法的工作原理,提出了一种基于脉冲编码与轮换的多电平SPWM调制策略。通过对正弦调制波的提取变换,进行单载波"量化"调制,并采用脉冲编码与轮换控制技术,对"量化"后的信号进行脉冲编码和脉冲轮换,均衡各逆变单元的输出电压与输出功率,以及单元内部电容电压。仿真结果表明,与同相层叠载波SPWM调制策略相比,该调制具有更好的控制效果和更小的计算量;另外,控制算法的消耗资源对比分析表明,所提的控制算法较常规的SPWM算法更节省硬件资源。     

A novel voltage clamped snubber circuit topology suitable for a multilevel inverter with lowered power loss performance

This paper presents a novel prototype of lowered loss snubber circuit topology suitable for multilevel voltage source‐inverters and rectifiers for high‐power applications. The reduced power loss characteristics and voltage capability performances of the proposed voltage clamped snubber circuit are evaluated relative to conventional RCD snubber circuits designed for four‐level voltage‐source inverters using IGBTs on the basis of experimental results. © 2004 Wiley Periodicals, Inc. Electr Eng Jpn, 150(3): 70–78, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20015     

一种无电解电容控制器的弱磁控制方法研究

研究并分析了无电解电容变频器的系统特性,电压电流随着网侧输入电压频率的二倍频脉动的特点,针对性地分析了对应的系统控制方案和控制方法.同时,针对无电解电容变频器的系统特性,弱磁控制不稳定和极易失控的特点,提出了一种适用于无电解电容变频器的弱磁控制方法,并在实际负载系统条件下验证了该弱磁控制方法在无电解电容变频器控制系统中的控制稳定性,同时对能效的提升改善效果.     

一种基于3D SVPWM调制的三相四桥臂逆变器控制方法

针对三相四桥臂逆变器控制系统,基于旋转坐标变换建立了系统模型,提出了一种正负零序分量解耦的控制方法,该方法可以减小三相不平衡负载下的输出电压不平衡度,并且对3D SVPWM发波方式做了简化,使得更有利于工程化实现。通过仿真和实验结果验证了该方法的正确性。     

An algorithm for controlling a multilevel voltage inverter

A vector algorithm for the control of a multilevel voltage inverter is presented. The algorithm is characterized by high efficiency and does not depend on the number of levels in the inverter; it is of methodical importance for understanding the principles based on which multilevel inverters operate.     

A reliable and efficient single-phase modular multilevel inverter topology

Bilevel inverters are replaced by multilevel inverters due to their capability of producing quality output voltage with low total harmonic distortion (THD). On the contrary, increase in number of semiconductor switches has questioned the reliability of the multilevel inverter topologies. To enhance the reliability, this paper proposes a single-phase five-level inverter topology with inherent fault-tolerant feature. The proposed inverter can sustain faults in sources and semiconductor switches by amending the switching combinations. No healthy switch is needed to be bypassed during the fault to ensure the optimum utilization of the switches. An analysis on the basis of reliability, cost, and efficiency is carried out of the proposed inverter and compared with the existing topologies. To prove the claim, the experimental results of the developed hardware model is analyzed and compared with the simulation results of MATLAB/SIMULINK.