Optimal pulse patterns of a nine-phase voltage source PWM inverter for use with a triple three-phase wound ac motor

The authors have already described the nine-phase inverter driving system providing both the triple three-phase voltage source inverter with 180-deg conducting period and the ac motor windings with triple three-phase construction. The nine-pulse inverter driving system used three small-capacity three-phase coupling reactors having special windings for current balance and reduction of higher harmonics. In addition, for voltage control, current balance, and waveform improvement, optimal PWM pulse patterns were applied to the six-phase inverter driving system using a three-phase coupling reactor to provide double three-phase construction. In the system based on the mode in the title, the PWM control was applied to the nine-phase inverter driving system described in the foregoing. The coupling reactors in the system balance the fundamental currents of three sets of three-phase inverters and also absorb higher harmonic voltages other than 18p±1 (p = 1, 2, …) orders. The optimal pulse patterns found by the approach to make the performance index minimum using the Lagrange multiplier method can be applied to the PWM to reduce the higher harmonic currents greater than those calculated by the modulation method comparing the sinusoidal signal wave with triangular carrier signal. This system can have a larger capacity than the six-phase PWM inverter driving system in which coupling reactors absorb higher harmonic voltages other than the 12p±1 orders and also improve output current waveforms. In addition, the system includes the capacity of coupling reactors slightly larger than the six-phase PWM inverter driving system but enables operation with smaller torque ripples and electromagnetic noises in low- to high-frequency ranges.     

用于抑制多相异步电动机定子谐波电流的电抗滤波器

电压型逆变器驱动多相异步电动机运行时,虽然降低了转矩脉动和转子谐波损耗,却在定子绕组出现了明显的低次谐波电流.在总结现有的方法基础上,提出一种新型的电抗滤波方法.电抗器采用和多相交流电机定子类似的电磁结构,适当调整绕组的分布,使在多相电机中不产生旋转磁场的谐波电流在滤波电抗器中产生旋转磁场.这些谐波电流在多相异步电动机中仅遇到漏电抗,在滤波电抗器中却遇到高值的耦合电抗,因而有选择地对定子中的显著谐波电流进行滤波.以六相移30°的绕组结构为例,对包括滤波器的多相异步电动机建立了数学模型并进行了仿真分析,仿真结果验证了电抗器的有效性.     

Voltage source inverter

A design optimization tool is developed for a three-phase voltage source inverter (VSI) with diode frontend rectifier. The insulated gate bipolar transistor (IGBT)-based pulsewidth modulation (PWM) voltage source inverter with diode front-end rectifier has become the converter of choice for three-phase ac-fed general-purpose industrial motor drives. The converter power stage, which mainly consists of the front-end rectifier, the inverter, the dc link capacitor, the harmonic and electromagnetic interference (EMI) filter, and the thermal management system, as shown in Figure 1 with a motor load, is the primary contributor to the overall converter cost and size. Since there are interdependencies and tradeoffs among components or subsystems in the power converter, it is very desirable to have a systematic methodology and tool for achieving a cost-optimized or size-optimized converter design while meeting the system performance requirement. A design tool will also reduce the development cycle and effort.     

电源变换器在风力发电中的技术研究

随着风力发电技术的快速发展,高性能的电源变换技术受到人们的广泛关注.在此采用基于DSP的数字控制技术,设计了一个新型的AC/DC/AC电源变换器.该变换器前级为三相两开关Boost PFC电路,采用DSP产生两路相位差为180°频率可变的PWM信号进行控制,实现了部分解耦控制,能有效减少输入电流的谐波含量并提高功率因数...     

OPTIMAL WINDING DESIGN OF A PERMANENT MAGNET MOTOR FOR SELF-CONTROLLED INVERTER OPERATION

ABSTRACT

This paper describes a novel design of the three-phase synchronous motor which is tailored to match the operational characteristics of the self-controlled inverter. The design is based on a square waveform distribution of the rotor radial B-fields and square waveform distributions of the winding densities of the stator phases around the periphery of the airgap. The motoring torque has minimal time harmonics. The design achieves a maximum power density for the frame size of the motor. It is ideally suited for permanent magnet synchronous motors.     

Four-switch Three-phase Inverter Performance Fed Sensorless Speed Control Induction Motor Drives Using Model Reference Adaptive System

Abstract—This article presents an investigation of four-switch inverter performance fed three-phase induction motor drives. Speed estimation is based on fundamental wave models using a model reference adaptive system as a speed estimator technique. The motor is fed from a four-switch three-phase inverter. A comparative study for sensorless speed estimation using a four-switch three-phase inverter, and a six-switch inverter is simulated and experimentally investigated at different operating conditions. Also, a comparison of system performance based on the four-switch inverter and conventional six-switch inverter in terms of speed response and total harmonic distortion of stator currents is presented. Experimental and simulation results at different points of operation are presented, verifying the robustness of sensorless speed estimation at different load levels. Sensorless speed estimation based on the four-switch three-phase inverter is quite acceptable considering its speed response.     

基于载波移相大功率并联逆变器输出谐波分析

以超导托卡马克核聚变实验装置(EAST)中的快控电源为背景,研究分析了采用载波移相PWM技术实现逆变器并联输出的系统设计方案,并利用双重傅里叶变换对逆变器并联输出谐波进行分析,建立其数学模型。仿真和实验表明,采用载波移相PWM技术实现逆变器并联输出可以消除低次谐波,提高等效开关频率,对实现电源系统大电流输出与快速响应具有良好效果。     

计及IGBT暂态特性的PWM逆变电路输出电压谐波分析

PWM逆变器以结构简单、控制灵活等优点广泛地应用于电力系统之中,但其IGBT暂态特性易受结温影响,导致PWM逆变电路输出电压易受温度影响而产生畸变。针对上述问题,文中首先确定IGBT暂态特性与结温关系;通过贝塞尔函数推导出IGBT开关延迟时间与PWM逆变电路输出电压谐波的数学关系;最后在Matlab/Simulink环境下搭建计及IGBT暂态特性的PWM逆变电路模型进行仿真。理论分析与仿真结果表明,IGBT开关延迟时间呈正温度系数关系;在计及IGBT开关延迟的情况下,PWM逆变电路输出电压新增直流与高次谐波成份,谐波总含量增大,电压总畸变率升高。     

随机频率PWM逆变器的分析设计

应用随机PWM方法可以使逆变器的输出电压频谱呈连续分布而不影响基波分量,这样由逆变器供电的电动机的声学噪声和机械振动就会大大减小。然而,由于RPWM机理的分析和设计对于一般工程师来讲是比较繁琐的,这就限制了RPWM的应用。本文提出了一种用于驱动感应电机的随机频率PWM逆变器,并给出了可实现的设计程序。首先,直观分析了随机信号对逆变器输出电压频谱的影响,其次,进行了相关的量化设计,最后,采用SIMULINK仿真和实验的手段对整个系统进行了分析。仿真和实验结果表明本文提出的RFPWM设计方案中,逆变器输出电压的频谱是均匀随机分布的,而且声学噪声和机械振动都得到有效抑制。     

一种新的分相控制式三相电流型五电平逆变器

在一个三相直接式多电平电流型逆变器（CSI）中利用PWM技术来消除输出电流谐波是非常困难的。文中提出了一类新的三相分相控制式电流型5电平逆变器拓扑。这类拓扑通过三相星形负载的中性线进行解耦，逆变器的每相都可以独立控制，因此可以将多电平PWM技术应用到该类逆变器以减小输出电流谐波。文中给出了一种多载波PWM技术的数字化实现方案。文中以单相逆变器单元为例介绍了三相5电平逆变器的工作原理。最后建立了一个三相分相式5电平CSI的实验系统，验证了文中的结论。随着超导储能系统技术的发展及其应用，电流型多电平变流器将具有广泛的应用前景。     

Harmonic analysis of the output voltage of a third‐harmonic‐injected inverter for LSM drives

The superconducting magnetic leviation railway system (MAGLEV) under development in Japan uses pulse‐width‐modulation (PWM) inverter for driving a linear synchronous motor (LSM). The inverter output voltage contains nonnegligible harmonics which cause harmonic resonances in the LSM system, and therefore harmonics of the output voltage have been analyzed in order to control such harmonic resonances. This paper applies a third‐harmonic injection method to the inverter for the purpose of enhancing the output voltage without changing the circuit configuration. It performs harmonic analysis of the output voltage of the inverter based on the third‐harmonic injection. Validity of the harmonic analysis is verified by computer simulation. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 160(1): 71–78, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ).     

基于DSP的三相PWM可控整流系统的设计

为了克服四象限变频调速系统中采用二极管整流带来的不足,用三相PWM整流器代替二极管整流器,设计了基于32位集成DSPTMS320F2812的三相PWM可控整流系统.提出了一种新的同步相位角度控制方案,提高了电网电压定向矢量角度的精度,简化了SVPWM算法,实现了能量以高功率因数的双向传递.实验结果验证了可控整流系统设计的正确性.     

PWM INVERTER FED INDUCTION MOTORS LOSSES EVALUATION

ABSTRACT

In this paper the authors deal with the problems concerning the steady state losses evaluation in medium power industrial induction motors supplied by PWM inverter. They present a method based on the no-load and short circuit tests. This technique seems to be very useful for the good obtained results and because it is quite similar to the standard no-load and short circuit tests used with sinusoidal voltage supply.

The method is based on some simple hypothesis that have been verified during the experimental tests by means of mathematical models. As a consequence, it is possible to compare the no-load and the short circuit tests under sinusoidal and PWM inverter supply considering the same rms fundamental voltage.

The method has been applied to a 7.5 kW induction motor supplied by a prototype PWM Voltage Source Inverter (VSI) modulated with a ramp comparison technique at a 1 kHz switching frequency.

The obtained results could be utilized in order to define some design criteria and the derating for standard induction motors supplied by PWM inverters.     

Comparison of PWM and PFM induction drives regarding audible noise and vibration for household applications

This paper is aimed at comparing the performance of pulse frequency modulation (PFM) and pulsewidth modulation (PWM) techniques regarding audible noise generated from inverter-driven induction motors. For the purpose of illustrating the performance of the two modulation techniques, a drive developed for washing machine applications is considered. First, the measured and simulated harmonic content of this inverter is compared with the measured harmonic spectrum of a three-phase input-output commercial variable-frequency inverter. It is found that despite the 8-bit processor inexpensive implementation, the total harmonic distortion (THD) of PFM is comparable to the THD of PWM in more sophisticated applications. It is discovered that the harmonic spectrum of PFM exhibits harmonics of smaller magnitude distributed over 0.9f/sub o/--2.1f/sub o/ (base switching frequency) range, as opposed to a smaller number of dominant harmonics of PWM. Next, the prototype drive is programmed to generate both sine-PWM and PFM waveforms. The motor is driven at several frequencies and the audible noise and vibration level of the motor is measured. It is observed that the type of current harmonic content of PFM leads to reduced noise and vibration.     

一种基于TMS320F2812的交流电机控制方案的实现

叙述了三相交流电机空间矢量脉宽调制(SVPWM)的原理,探讨了采用空间矢量脉宽调制三相桥式电压型逆变器的电压输出能力。介绍了一种基于DSP生成SVPWM波形的方法,给出了采用最新的TMS320F2812DSP实现SVPWM控制的方案,最后给出了在三相交流电机上的试验结果。     

Performance of a High-Speed Motor Drive System Using a Novel Multilevel Inverter Topology

The performance of a novel multilevel six-switch (SS) three-phase inverter drive is examined for low-voltage high-speed motor applications. The switching losses of hard-switched voltage-source-inverter topologies place limits on the maximum feasible switching frequency. When operating at higher fundamental frequencies, this results in low-frequency modulation ratios and either high load harmonic currents that cause excessive rotor heating or larger than desired output reactors with a large fundamental voltage drop. The multilevel inverter structure examined offers an increased number of output pulsewidth-modulated (PWM) voltage levels, higher frequency PWM output waveforms, reduced dead-time effects, and a significant reduction in harmonic content. These features reduce the total losses in the motor load when compared to the standard SS three-phase inverter. The harmonic reduction provided by the multilevel topology relative to the standard inverter is experimentally demonstrated with a 15-hp 18 000-r/min induction machine.     

基于ADMC401的三相交流感应电机SVPWM变频调速

介绍了以ADMC401DSP芯片为核心的三相交流感应电机SVPWM变频调速系统,具有位置反馈、速度反馈和电流反馈三闭环结构,通过电流反馈及神经元PID控制算法处理偏差数据,减少逆变器输出电流的谐波成分及电动机的谐波损耗,以较低的成本实现三相交流电机连续控制。     

UPS逆变器谐波抑制环的分析与设计

在非线性负载电流峰值系数较大时,不间断电源UPS(uninterruptible power supply)逆变器的输出电压的总谐波失真度THD(total harmonic distortion)难以达到标准要求。基于dq0同步旋转坐标系的谐波抑制方法可消除指定次谐波,从而改善输出电压的THD。介绍了该谐波抑制方法应用于三相四线制UPS逆变器的控制环路结构,并推导了谐波抑制环在dq0同步旋转坐标系下的控制方程,从而得到了环路被控系统的动态模型。在此基础上,改进了谐波抑制环的环路结构以实现dq轴在低频段的解耦,并设计了环路控制参数。最后,在三相四线制T型三电平逆变器平台上通过实验验证了谐波抑制环设计的有效性。     

Optimal power control strategies for neutral point clamped (NPC)inverter topology

A programmed pulsewidth modulation (PWM) technique for selectively eliminating several lower-order harmonics at the output of a neutral point clamped (NPC) inverter topology is investigated. The switching function approach is utilized to derive relevant analytical expressions for input/output variables. A thorough evaluation of the NPC inverter topology based on the switching function approach is described. Optimal power control strategies for an NPC inverter employing programmed PWM patterns are proposed. For a constant-frequency variable-voltage NPC inverter power supply, the proposed strategy is to maintain a minimum specified total harmonic distortion employing a low-output impedance filter. In the case of an NPC inverter powering an AC motor drive, the proposed strategy is to maintain a minimum specified harmonic current factor. The proposed power control strategies are achieved without substantial increase in inverter switching frequency and are therefore suitable for high-power applications employing gate-turn-off-thyristor (GTO) type devices     

Programmed PWM techniques to eliminate harmonics: a criticalevaluation

Programmed pulsewidth modulators (PWMs) eliminating several lower-order harmonics generate high-quality output spectra, which in turn result in minimum current ripple and reduced torque pulsations, thereby satisfying several performance criteria and contributing to overall improved performance. Several programmed PWM switching patterns to eliminate harmonics in the output spectra of single-phase and three-phase inverters are possible. Each of these leads to a specific advantage in single- and three-phase inverters, depending on the application. First, the superiority of programmed PWM techniques over the conventional carrier-modulated PWMs is established. Next, a critical evaluation of the programmed PWM schemes on the basis of applications for single- and three-phase inverters is used to provide a framework and guidelines for the selection of the appropriate technique for each application area. Evaluation criteria include harmonic loss factor and total harmonic distortion factors defined at the input and output of the inverter terminals. Finally, a simple low-cost solution for obtaining the required PWM switching points is proposed. Selected results are verified experimentally