An application of PSO technique for harmonic elimination in a PWM inverter

Harmonic elimination problem in PWM inverter is treated as an optimization problem and solved using particle swarm optimization (PSO) technique. The derived equation for computation of total harmonic distortion (THD) of the output voltage of PWM inverter is used as the objective function in the PSO algorithm. The objective function is minimized to contribute the minimum THD in the voltage waveform and the corresponding switching angles are computed. The method is applied to investigate the switching patterns of both unipolar and bipolar case. While minimizing the objective function, the individual selected harmonics like 5th, 7th, 11th and 13th can be controlled within the allowable limits by incorporating the constraints in the PSO algorithm. The results of the unipolar case using five switching angles are compared with that of a recently reported work and it is observed that the proposed method is effective in reducing the voltage THD in a wide range of modulation index. The simulated results are also validated through suitable experiments.     

Elimination of lower order harmonics in Voltage Source Inverter feeding an induction motor drive using Evolutionary Algorithms

Selective Harmonic Elimination technique is one of the control methods applied in Voltage Source Inverters to eliminate the harmonics. However, finding the solutions for the harmonic reduction is a difficult problem to be solved. This paper presents an efficient and reliable Evolutionary Algorithms based solution for Selective Harmonic Elimination (SHE) switching pattern to eliminate the lower order harmonics in Pulse Width Modulation (PWM) inverter. Determination of pulse pattern for the elimination of lower order harmonics of a PWM inverter necessitates solving a system of nonlinear transcendental equations. Evolutionary Algorithms are used to solve nonlinear transcendental equations for PWM–SHE. In this proposed method, harmonics up to 19th are eliminated using Evolutionary Algorithms without using dual transformer. The experimental results are obtained and are validated with simulations using PSIM 6.1 and MATLAB 7.0.     

Field programmable gate array implementation of variable common mode injection PWM for three-level inverters

This paper proposes implementation of variable common mode injection pulse width modulation (VCMIPWM) scheme using field programmable gate array (FPGA) for three-level inverters. The waveform quality of the inverter output can be improved using suitable PWM control technique. Optimal harmonic profile may be obtained by centring the middle space vectors in a switching cycle. If the expression of common mode voltage calculated for two-level inverter is applied to multilevel inverter, the middle vectors may not be centred. So, the harmonic performance is poor. There is a need to calculate the amount of common mode injection required to centre the middle space vectors in a switching cycle. The amount of common mode injection depends on the magnitude of the reference vectors. The common mode voltage is calculated for various cases and is injected with the sinusoidal reference vector to produce modified reference vectors. Harmonic performance of fixed common mode injection pulse width modulation (FCMIPWM) and VCMIPWM has been compared with the existing sinusoidal PWM (SPWM). In order to make use of the theoretical advantages of the VCMIPWM, this paper proposes the implementation of this PWM using FPGA. Simulation and experimental results are presented in this paper.     

Design and implementation of ANN-based SAPF approach for current harmonics mitigation in industrial power systems

This article describes with Shunt Active Power Filter (SAPF) for compensation of reactive Power (P), current harmonics. An ADALINE based neural network current estimator can control the SAPF to maintain sinusoidal source currents and unity Power Factor (PF). The three-phase (III-Phase) load currents are sensed and measured by Least Mean Square(LMS) algorithm based on ADALINE, the weights obtained with the help of online calculation, and then these weights are multiplied with the help of unit vector, which gives the fundamental frequency of Load Currents (LC). The DC link voltage (V) of the V Source Converter, maintained at a constant value, and it can work as the SAPF, and various simulation results are presented under the steady-state conditions using the PI controller. The switching action of VSC is performed using Hysteresis Current Control based on pulse width modulation, which makes the source currents should follow the reference source currents. The MATLAB based simulation results and implementation results are obtained to determine the efficacy of the SAPF with ADALINE based neural network control for load compensation. SAPF system meets IEEE Standard 519 recommended harmonic standards for different rated nonlinear loads under balanced supply conditions.     

三电平有源中点钳位型微网储能变流器直流侧中点电压优化控制策略

对三电平有源中点钳位型微网储能变流器的直流侧中点电压平衡优化控制策略进行了研究.由于三电平半周期对称特定谐波消除脉宽调制方法(selected harmonic elimination pulse width modulation,SHEPWM)方程具有无数组解,且每组解对应的开关状态矢量不同.研究了特定谐波消除脉宽调制方法方程不同的解对应的开关状态矢量及其对中点电压的影响.提出在每个周期动态选择合适的解使中点电压趋于平衡的控制策略.该控制策略在消除特定低次谐波的同时,有效的控制了直流侧中点电压波动,因此提高了微网储能变流器并网输出电能质量和降低了对输出滤波器的设计要求.最后搭建了三电平微网储能变流器仿真模型和实验平台对所提出的控制策略进行验证,实验结果表明了该控制策略的有效性.     

降低异步电动机电磁噪声的RSVPWM变频方法

高次谐波产生的电磁噪声是当前高性能PWM逆变器存在的主要问题之一.分析PWM波的功率谱密度可知,固定的开关频率是导致电磁干扰的主要原因.针对这一点,提出了用随机改变开关频率的空间矢量调制方法（即RSVPWM法）消除电磁噪声的方案.在基于DSP的异步机变频调速系统实验平台上,进行了RSVPWM法和传统SVPWM法的对比实验,结果表明,RSVPWM法不仅保证了系统的优良调速性能,而且降低了异步电动机的电磁噪声.     

An ultra-high-speed motor driver with hybrid modulations

An ultra-high-speed motor driver with hybrid modulations is proposed in this paper. The speed range of a spindle motor is wider and trends to ultra-high, but the traditional driver which provides either sinusoidal pulse width modulation or six-step modulation could not support so wide speed range. Normally, the variable voltage variable frequency control is used to support different type motors, then, sinusoidal pulse width modulation (SPWM) is chosen in low speed range drivers and six-step is picked in high-speed application. In this paper, the hybrid modulation driver with adjustable DC bus voltage is proposed, and the modulation could be selected for different motor and speed by users. For lower switching power loss, the six-step modulation is better when ultra-high-speed application. For low speed range, the trapezoidal pulse width modulation is used to replace the SPWM for the reduction of switching power loss. The experimental results show the performance of proposed driver.     

基于频率自适应滤波算法的脉冲电能计量方法

准确估计电力电子设备工作时所产生谐波的功率对脉冲电能计量具有十分重要的意义.提出归一化频率自适应的谐波功率计量算法.首先通过该方法分解出电机模型电路中被污染信号的各次谐波成分,进而实现对电机中谐波有功功率的实时跟踪.接着,以一组富含时变谐波的实测电火花信号为待处理信号,验证该算法在典型电火花脉冲电源信号谐波功率计量方面的应用.仿真结果表明,该算法在频率时变脉冲信号的电能计量方面具有快速性和准确性.     

离线开关变换器中混沌调制技术的比较研究

论文研究了混沌调制技术在实用开关变换器中抑制电磁干扰的效果。所研究的混沌调制技术包括混沌脉冲宽度调制和定占空比混沌载频调制两种模式。从实用化的角度出发,建立了双管正激变换器的元件级电路仿真模型,通过对两种混沌调制模式与周期PWM模式下信号频谱的分析比较说明,混沌调制技术能有效降低谐波峰值,改善了电磁兼容性。此外,文章还分析了混沌调制对输出电压纹波的影响。研究表明在开关变换器中应用混沌调制技术具有实际应用前景。     

An artificial bee colony-least square algorithm for solving harmonic estimation problems

Solving harmonic estimation problems in power quality signals has attained significant importance in recent times. Stochastic optimization algorithms have been successfully employed to determine magnitude of this information in an unknown signal contaminated with noise or containing additive dc decaying components. The present paper shows how a recently proposed stochastic optimization algorithm, called artificial bee colony algorithm, can be hybridized with least square algorithm to solve these problems effectively. The proposed algorithm has been tested for a series of case studies employing different benchmark environment situations and our extensive simulation tests validate the usefulness of the proposed algorithm and it could largely outperform several competing simulation algorithms, proposed in the recent past. The effectiveness of the proposed algorithm is further demonstrated for those situations where the number of harmonics present in the signal is also not known, along with the magnitude and phase of each harmonic.     

Selective Harmonics Elimination Technique for Artificial Bee Colony Implementation

In this research, an Artificial Bee Colony (ABC) algorithm based Selective Harmonics Elimination (SHE) technique is used as a pulse generator in a reduced switch fifteen level inverter that receives input from a PV system. Pulse width modulation based on Selective Harmonics Elimination is mostly used to suppress lower-order harmonics. A high gain DC-DC-SEPIC converter keeps the photovoltaic (PV) panel’s output voltage constant. The Grey Wolf Optimization (GWO) filter removes far more Photovoltaic panel energy from the sunlight frame. To eliminate voltage harmonics, this unique inverter architecture employs a multi-carrier duty cycle, a high-frequency modulation approach. The proposed ABC harmonics elimination approach is compared to SHE strategies based on Particle Swarm Optimization (PSO) and Flower Pollination Algorithm (FPA). The suggested system’s performance is simulated and measured using the MATLAB simulation tool. The proposed ABC approach has a THD level of 4.86%, which is better than the PSO and FPA methods.     

永磁同步电动机直接转矩控制策略研究

研究了基于无速度传感器技术的永磁同步电动机直接转矩控制策略,该策略将空间矢量脉宽调制技术应用到了电压源逆变器的开关序列选择中;通过滞环控制器控制磁链和转矩,消除了脉宽调制的延迟;采用低通滤波器实现了电压和电流的谐波抑制。仿真结果表明,采用该策略后,电动机的实际速度与不同转矩响应下的预计速度相似,加速到参考速度所需的时间很短,跟踪也很好。     

基于谐波线性化的滞环电流优化控制

滞环控制的PWM变换器是强非线性环节,难以通过优化控制和常规线性化处理来提高电流控制质量.为此,分析了滞环电流控制原理、谐波线性化方法及系统稳定性,得到了滞环电流控制传递函数模型,时滞和环宽与其他参数的一般关系以及系统自振荡频率的计算方法.根据滞环电流控制的特点,提出了将谐波线性化方法与ITAE优化控制律相结合的方法,以实现对PWM变换器的优化控制.Matlab仿真结果表明了所提出方法的有效性.     

Range,radial velocity,and acceleration MLE using frequency modulation coded LFM pulse train

Linearly frequency modulation (LFM) pulse train and linearly stepped frequency (LSF) pulse train are mostly used in radar systems. However, the estimation performance of target motion parameters may be affected by the high recurrent lobe levels and the range–Doppler coupling phenomenon appearing in ambiguity function (AF). In multi-target scenarios, the estimation performance becomes even worse. The Costas frequency-modulation coded (CFMC) LFM pulse train has an ideal thumbtack-shaped AF, thus it can provide motion parameter estimation with high precision. However, the estimation of target motion parameter for the coherent CFMC LFM pulse train has not been investigated in depth. In this paper, we first analyze the properties of the AF of the CFMC LFM pulse train. Based on its convexity and narrow mainlobe width, a fast method to implement the maximum likelihood estimator (MLE) is proposed to estimate the motion parameters. To reduce the computation complexity, the Chirp-Z Transform (CZT) is introduced. Then, the Cramer–Rao lower bounds (CRLBs) on range, velocity and acceleration for frequency-modulation coded (FMC) pulse train are derived. It is shown that the CRLBs are relevant to the frequency coding patterns. Finally, Monte Carlo simulations are performed to verify the performance of the MLE. The results show that the performance of our proposed method can achieve the CRLBs when the signal-noise ratio (SNR) is higher than the threshold SNR.     

Current control of a PWM power amplifier by an approximate 2-degree-of-freedom digital controller

There is a need for robust current control of a pulse width modulation (PWM) power amplifier whose transient response characteristics do not deteriorate with extensive load changes and/or direct-current power supply voltage changes. In this article, we propose a digital robust controller with bumpless mode switching to control the current of a PWM power amplifier to satisfy the demands and extend the range of an inductive load width. It is necessary to measure the value of the load in order to implement this bumpless mode switching automatically depending on the load range. Therefore, a method of estimating the inductive load is shown. The bumpless mode switching is automatically performed by estimating an inductive value without specifying the value of the inductive load beforehand. That is, the value of the inductive load is estimated during the DDC execution, and the control mode is automatically switched bumplessly according to this estimated value. A digital controller equipped with inductance estimation and bumpless mode switching is realized by a DSP. Some experiments show that the digital controller with the proposed bumpless mode switching can satisfy larger specifications.     

考虑谐波影响的开关磁阻电机无位置技术研究

针对用传统傅里叶级数相电感模型估计开关磁阻电机转子位置时直接忽略高次谐波,仅考虑到基波或者二次谐波,导致位置估计精度不高的问题,提出了一种考虑谐波影响的开关磁阻电机无位置控制方法.该方法通过对电感进行坐标变换以及差值电感辨识,消除了傅里叶级数电感的直流分量、偶次谐波分量以及三的倍数次谐波分量.选取谐波含量最少的差值电感...     

参数音频编码中的正弦波参数提取

研究了语音编码中基于倒谱的基音检测算法，并把它应用到参数音频编码中，提出了基于倒谱的正弦波参数提取法。本文根据倒谱的特性，结合音频信号的特征，利用前后帧的相关性和各次谐波的能量，有效保证了基频及其各次谐波在较大频率范围内的正确提取。另外结合谐波和单谱线提取，提高了算法效率。     

三相脉宽调制整流器的约束预测控制

本文将基于并行神经网络优化的约束模型预测控制(MPC)应用于脉宽调制(PWM)整流器中,提高了电网的质量.在三相静止坐标系下,建立了三相PWM整流器的解耦数学模型,采用约束模型预测控制策略,突破了有限集和无约束条件下预测控制的局限性.为了提高单步优化的速度,采用神经网络优化算法求解模型预测控制的在线优化.在保证系统单位功率因数的前提下,当系统负载突然变化时,具有快速动态响应稳定输出直流电压的性能.采用FPGA控制器实现并行计算,减少了预测控制算法的计算时间.最后,通过仿真和实验结果得到,采用本文的控制策略,总谐波失真(THD)降低了2.5%,达到稳态的时间大约是PI控制算法的五分之一,为12 ms,验证了该方法的可行性和有效性.     

一种推力恒定的RCS控制系统指令分配方法

高超声速飞行器再入段初期，所处大气环境空气稀薄，空气舵已无法提供足够力矩来维持姿态稳定，因此就需要反作用控制系统（Reaction Control System,RCS）来提供姿态稳定力矩。针对给定的飞行器RCS八喷管配置方案，基于查表法和脉宽调制，提出了一种能够维持飞行器系统姿态稳定的静态指令分配方法。给出了高超声速飞行器六自由度状态方程，采用一阶滑模控制算法进行姿态稳定控制；基于查表法思想和冲量等效的脉宽调制原理，完成了无故障情况下八喷管指令分配组合表的设计，并根据工程实际对组合表进行容错优化；设计了能够对单推力器发生卡死故障具有容错性的指令分配优化组合表，并采用脉宽调制方法对控制指令进行调制从而获得推力器的开关指令。仿真验证了该指令分配方法能够维持系统姿态稳定，提高控制系统的控制效率，有效解决了八喷管配置以及单喷管卡死故障情况下的指令分配问题。     

在非视距传播环境下无线定位的AOA算法

非视距传播(NLOS)是蜂窝无线定位的一个关键的问题,要提高无线定位的精度,必须有效减小非视距传播的影响.基于一种适合对各种定位算法进行分析的基于几何结构的单次反射统计信道模型(GBSB),提出一种减小非视距传播影响的AOA定位算法,该算法利用临近基站与移动台构成的三角函数关系和波达方向的最大角度扩展作为优化的约束条件,将基于波达方向(AOA)的无线定位问题转化为有约束的最优化问题,从而提高了无线定位的精度.仿真结果证明了该算法的有效性.