一种基于空间矢量PWM的死区效应补偿策略研究

该论文详细分析了电压型PWM逆变器死区对输出电压和输出电流的影响,并基于预测电流控制算法,提出了一种新的补偿算法,对电压损失进行补偿.以达到使最终的输出电流跟踪于期望电流的目标。最后把该算法应用在SVPWM逆变电路中,进行了仿真和实验板的调试,仿真分析和实验结果都表明该算法对死区补偿具有良好的有效性和可行性,并且补偿算法完全由DSP完成,不需要增加硬件电路。     

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。     

逆变器电压补偿参数离线辨识及其应用研究

在异步电机三相逆变中,当电机低速运行时,因输出电压较低,由死区时间和信号传播延迟造成的电压损失会使输出电流发生明显的畸变。为改善逆变器输出电流波形,需要进行电压补偿。常用的电压补偿方法有电压反馈补偿、电流反馈补偿、死区解耦补偿、自适应死区补偿等,最常用且容易实现的方法就是电流反馈补偿。电流反馈补偿需要知道电流采样通道及开关器件延迟、开关器件压降、死区时间等参数,为避免直接查阅芯片资料造成的参数误差,本文提出了一种逆变器电压补偿参数离线辨识方法,并研究了该方法在电压补偿中的应用。     

逆变器中死区效应及其补偿策略分析

对死区时间对逆变器输出电压的影响进行了分析。死区效应引起的电压偏差可以等效为一个与电流相为相反的方波。并对死区效应的补偿策略进行了研究。     

永磁同步电机矢量控制中死区补偿技术的研究

本文针对永磁同步电机矢量控制系统,分析了死区电压矢量对三相输出电压的影响以及死区电压矢量与定子电流方向的关系,提出了一种基于SVPWM矢量控制的死区补偿方法。定子电流矢量角根据计算得出,避免了传统方法在相电流过零处由于电流方向检测不准而影响补偿效果。该方案无需增加硬件电路,对软件进行修改即可实现。仿真试验结果证实了该方法的有效性。     

单相桥式PWM逆变器死区补偿的一种方法

为了更好的了解脉冲宽度调制控制技术及其在实际电路中的应用,文中以单相SP-WM逆变电路为控制对象,分别从PWM的产生机制、死区补偿和输出电压与输出电流等方面详细介绍了死区补偿的一种方法。并对逆变器的工作模态、电流回路做了具体的分析。文中结合图表和文字说明进行分析,形象直观、简洁易懂。     

一种多旋转坐标系下的死区谐波电压补偿方法

分析了死区时间对逆变器输出电压谐波的影响,结合逆变器在旋转坐标系上的数学模型,提出了多旋转坐标系下死区谐波电压补偿策略,即在旋转坐标系下在线检测死区谐波电压,通过谐波电压的反馈控制对死区谐波电压进行消除。该策略无需对桥壁电流极性进行判断即能达到消除死区电压的目的。最后,在工频逆变器上通过实验验证了该补偿方法对谐波电压检测以及死区谐波电压消除的有效性。     

基于模糊控制FOC的永磁同步电机死区补偿

为了保证死区时间效应的消除效果,针对实际使用中永磁同步电机解耦参数不定、逆变器存在个体差异及温漂,并且静态补偿效果差的问题,提出一种在理论计算调整SVPWM占空比的基础上,基于模糊控制算法和磁场定向控制算法(FOC)的永磁同步电机死区补偿方法.通过采集和观测实时的输出电压等数据,动态调节SVPWM死区补偿大小,使输出波...     

异步电动机直接转矩控制中的死区效应的仿真研究

逆变器是直接转矩控制系统主电路中的关键部件。逆变器死区的设置虽然防止了逆变器器件的直通,同时也带来了死区效应,特别是对直接转矩控制系统的影响更是明显。本文通过分析异步电动机直接转矩控制系统中死区的生成及死区对电动机和整个系统的影响,定义了偏差电压矢量,并在此基础上,提出了一种死区补偿分析算法。该方法不需附加硬件,只需对原控制软件进行修改。仿真结果显示,在直接转矩控制系统中加入死区补偿,能有效改进电动机定子电流波形,使转矩脉动减小,整个系统的运行性能得到了一定的改善。     

死区对PWM逆变器共模电压的影响及其抑制方法

变频器采用的空间矢量脉宽调制(SVPWM)会产生共模电压,后者对变频器和电机产生危害。改进的空间矢量脉宽调制法有利于降低共模电压,但由于没有考虑死区的影响,实际效果受到较大影响。文章详细研究了死区对PWM逆变器共模电压的影响,并提出了一种消除死区的方法来抑制死区影响并对共模电压起到一定的抑制作用,使改进的空间矢量脉宽调制法能够真正达到预想的效果。最后通过Matlab仿真实验,验证了该方法的有效性。     

A dead-time minimization algorithm for improving the output characteristics of the PWM inverter

The dead time in an inverter is necessary to prevent the short circuit of the DC source. However, the dead time may cause serious problems such as waveform distortion, voltage drop, increased torque ripple and heating of the motors. In this paper, a dead-time minimization algorithm is proposed for improving the inverter output performance. The adverse effects of the dead time are investigated, focusing on the voltage drop and the distortion factor of inverter output current. The proposed algorithm consists of forbidding unnecessary triggers for the inverter switches that are not turned on although the gate drive signal is impressed. The proposed algorithm is explained in terms of the conduction modes of the output currents. The validity of the proposed method is verified by comparing the simulated and experimental results with those of the conventional methods. It is concluded from the results that the proposed algorithm can reduce the output current harmonics. Further, the output voltage can be equal to the reference value and the number of inverter switchings can also be reduced to 50% compared with those of conventional methods.     

On-line compensation of dead-time and inverter nonlinearity with disturbance voltage observer

This paper discusses and analyses a simple on-line compensation scheme for dead-time and inverter nonlinearity in the pulse width modulated (PWM) voltage source inverter (VSI). Dead-time effect and voltage drop in switching devices cause nonlinearity between reference and output voltage. In a conventional three-phase six-switch inverter, this nonideal condition adds extraneous harmonics that badly disturb voltage characteristics. In its turn, voltage disturbance causes distortion of the current waveform and degrades performance. In this paper, an on-line dead-time compensation method based on inverse dynamics control is proposed, and it is much simpler than conventional full/reduced order observation methods adopted in dead-time compensation. Disturbance voltages are observed on-line with no additional circuitry or off-line measurements. The observed disturbance voltages are fed back to the voltage reference for compensation. Stability problem of the proposed observer arisen from inverter delay and parameter mismatch was analysed. The proposed method is applied to a surface-mounted permanent-magnet synchronous motor (SPMSM) drive. The effectiveness of the proposed scheme is validated by the experimental results.     

无源器件辅助换流的单相全桥软开关逆变器

为提高单相全桥逆变器的转换效率,提出了一种无源器件辅助换流的单相全桥软开关逆变器拓扑结构,通过在逆变器桥臂上增加辅助谐振电路,实现了开关器件的软开关动作.辅助谐振电路中无辅助开关器件,只含有电感、电容和二极管等少量无源器件,这有利于降低辅助电路的成本,而且不会使逆变器的控制策略复杂化.此外,在逆变器处于死区状态时,负载电流能通过辅助谐振电路续流,可以改善逆变器输出电流波形的畸变率,减小了死区的不利影响.文中详细分析了电路的工作过程,在功率为4kW的单相实验样机上进行了实验验证,获得的实验结果表明在轻载和满载时逆变器的开关器件都能实现软开关,逆变器输出电流波形的畸变率都得到了改善.因此,该无源器件辅助换流的单相全桥软开关拓扑结构对于提高逆变器的性能具有重要意义.     

An accurate approach of nonlinearity compensation for VSI inverter output voltage

An accurate nonlinearity compensation technique for voltage source inverter (VSI) inverters is presented in this paper. Because of the nonlinearity introduced by the dead time, turn-on/off delay, snubber circuit and voltage drop across power devices, the output voltage of VSI inverters is distorted seriously in the low output voltage region. This distortion influences the output torque of IM motors for constant V/f drives. The nonlinearity of the inverter also causes 5th and 7th harmonic distortion in the line current when the distributed energy system operates in the grid-connected mode, i.e., when the distributed energy system is parallel to a large power system through the VSI inverter. Therefore, the exact compensation of this nonlinearity in the VSI inverter over the entire range of output voltage is desirable. In this paper, the nonlinearity of VSI inverter output voltage and the harmonic distortion in the line current are analyzed based on an open-loop system and a L-R load. By minimizing the harmonic component of the current in a d-axis and q-axis synchronous rotating reference frame, the exact compensation factor was obtained. Simulations and experimental results in the low frequency and low output voltage region are presented.     

Dead-Time Elimination of PWM-Controlled Inverter/Converter Without Separate Power Sources for Current Polarity Detection Circuit

This paper will present a dead-time elimination scheme for a pulsewidth-modulation (PWM)-controlled inverter/converter. The presented dead-time elimination scheme does not require separated power supplies for freewheeling-current detection of high- and low-side power devices. The presented scheme includes the freewheeling-current polarity detection circuit and the PWM control generator without dead time. It will be shown that the presented scheme eliminates the dead time of PWM control for inverter/converter and therefore dramatically improves output voltage loss and current distortion. Experimental results derived from a field-programmable-gate-array-based PWM-controlled inverter are shown to demonstrate the effectiveness.      

Inverter Nonlinearity Compensation in the Presence of Current Measurement Errors and Switching Device Parameter Uncertainties

This paper proposes a compensation strategy for the unwanted disturbance voltage due to inverter nonlinearity. We employ an emerging learning technique called support vector regression (SVR). SVR constructs a motor dynamic voltage model by a linear combination of the current samples in real time. The model exhibits fast observer dynamics and robustness to observation noise. Then the disturbance voltage is estimated by subtracting the constructed voltage model from the current controller output. The proposed method compensates for all of the inverter nonlinearity factors at the same time. All the processes in estimating distortions are independent of the dead time and power device parameters. From the analysis of the effect on current measurement errors, we confirmed that the sampling error had little negative impact on the proposed estimation method. Experiments demonstrate the superiority of the proposed method in suppressing voltage distortions caused by inverter nonlinearity     

Inverter output voltage synthesis using novel dead timecompensation

In this paper, a novel dead time compensation method is presented that produces inverter output voltages equal to reference voltages. An experimental result is also presented to demonstrate the validity of the proposed method. It shows that the compensation of the dead time is possible up to a sub-microsecond range. Also, the reference voltage can be used as a feedback value, which is essential for sensorless vector control and flux estimation. The method is based on space vector pulsewidth modulation (PWM) strategy and it can be carried out automatically by an inverter controller for initial setup without any extra hardware