基于Matlab对AC/DC/AC电源的死区效应的谐波分析及仿真

对AC／DC／AC电源所固有的死区效应带来的谐波进行了数学分析，得出了在固有谐波基础上死区时间对于此类型电源所产生的电压波形的影响。并利用Matlab软件对此类电源建立了仿真模型，特别是利用已知模块实现了死区时间的仿真模型。对于产生的谐波进行了FFT分解，重点分析了死区效应使电源电压波形所产生的谐波分量。     

三相电压型逆变器优化控制策略研究

三相电压型逆变器控制中,适当提高系统开关频率可以优化输出电压波形,但同时会带来系统开关损耗的增加,且死区时间增加从而使得死区效应影响变大。提出一种基于两相调制SVPWM的优化无死区控制方案,两相调制SVPWM算法可以减少开关损耗,提高电压利用率,优化无死区控制可以从根本上消除死区带来的不良影响。通过MATLAB/SIMULINK仿真对该方法进行了验证。     

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。     

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。     

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。     

输出电压估计误差的研究

本文在详细分析了直流母线电压和逆变器三相开关管状态进行输出电压估计的基础上，研究了死区时间和开关管非线性特性对输出电压估计的影响，并实现了以TMS320F240为核心的简易矢量控制系统。针对1.1kW异步电机进行了实验，结果表明死区时间与开关管非线特性对输出电压估计具有很大影响。     

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。     

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。     

一种基于SVPWM的死区补偿策略

对三相桥式逆变器死区效应进行了理论分析,提出了一种改进的基于SVPWM的死区补偿策略。理论分析和实验结果均表明该补偿策略能有效改善死区效应引起的电流畸变,且运算量小,实用性强。     

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。     

Dead-time effect and compensations of three-level neutral pointclamp inverters for high-performance drive applications

Due to the use of high-power devices and slow-switching frequency in a three-level neutral point clamp inverter, the dead-time effect may not be compensated sufficiently fast by using methods developed for the two-level inverter. In this paper, the dead-time effect in a three-level inverter with snubber circuits is analyzed to reveal that it does not only depend on load current direction, but also on magnitude. The snubber network also plays an important role in determining the output phase voltage during the dead-time period. Software techniques are proposed to compensate the dead-time effect as soon as it occurs as demanded by the slow-switching frequency. Experimental results show their effectiveness     

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.     

An adaptive dead-time compensation strategy for voltage source inverter fed motor drives

This paper presents an adaptive dead-time compensation strategy to obtain fundamental phase voltage for inverter fed vector controlled permanent magnet synchronous motor drives. The amplitude of phase dead-time compensation voltage (DTCV) to compensate disturbance voltage due to undesirable characteristics of inverter, such as dead-time, turn-on/off time of switching devices, and on-voltages of switching devices and diodes is adaptively determined according to a dead-time compensation time (DTCT). DTCT is identified on-line with using a /spl delta/-axis disturbance voltage in the current reference frame that is synchronized with current vector. The /spl delta/-axis disturbance voltage is estimated by a disturbance observer. The accuracy of identified DTCT is experimentally confirmed by calculating the mean absolute percentage error (MAPE) between a calculated active power and a measured one. MAPE for adaptive DTCT is almost within 5% at any operating point.     

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.      

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.     

The analysis and compensation of dead-time effects in PWM inverters

The quantitative prediction of the dead-time effect in pulse width modulated (PWM) inverters is addressed. Through analysis and simulation it is shown that the effect results in a decrease of the fundamental component and an increase in the low-order harmonics in the output voltage of the inverter. To compensate the effect, two simple methods, which are adequate for sinusoidal PWM and memory-based PWM, respectively, are presented. Experimental results show the validity of the analysis and the usefulness of the compensation methods     

准恒频电流滞环控制的死区补偿

详细分析了逆变器的死区效应,结合变环宽准恒频滞环控制的特点,本文采用按电流极性对脉冲给予补偿的方法,并对环宽进行修正。另外针对零电流箝位现象和滞环控制本身造成的过零点附近电流极性难以检测的问题,采用零电流附近极性给定策略;针对峰值处占空比为1的情况,通过对环宽进行限幅,减小电压波形的畸变。仿真和实验验证了该方案的可行性...