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。     

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。     

自适应滤波在电流矢量死区补偿方法中的应用

电机PWM控制方式存在死区问题,严重影响了电机的运行性能。本文在电流矢量死区补偿方法基础上,分析了检测电流的噪声对补偿方法的影响,认为噪声极大干扰了电流矢量的计算,破坏了补偿的准确性。为消除噪声的影响,本文提出了自适应滤波方法,并通过动态收敛系数方法提高滤波器响应速度。实验结果表明这种滤波方法能有效提取信号中的直流成份,获得准确的分解电流,非常适用于基于电流矢量的死区补偿方法。相对其他噪声去除方法,该算法非常简洁,易于编程实现,占用资源少,实用有效。     

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。     

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。     

基于单相SVPWM的可变死区算法

针对单相逆变器固定死区时间注入调制波导致输出电压谐波畸变率较高等问题,本文提出一种将可变死区时间注入单相SVPWM调制波有效矢量组的方法.该方法将一系列非线性因素等扰动因素看成扰动电压,采用干扰观测器对扰动电压进行估算补偿,并将估算补偿电压换算成死区时间,补偿到SVPWM调制波有效矢量组导通区间.实验证明该方法相比传统...     

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。     

中压三电平逆变器矢量控制系统的几个特殊技术

本文介绍了三电平逆变器矢量控制系统的5项关键技术：输出电压电流测量；输出滤波器对矢量控制影响的对策；定子电势计算中电流微分对策；新磁链观测电压模型；直流电流调节块的预近代和电机参数的补偿。     

变频器逆变单元死区效应分析及其补偿

在SPWM控制的变频器中,死区的加入会使输出电压和电流波形发生畸变,使谐波分量增加。文中详细分析了死区对逆变器输出电压基波的影响,并在尽量不增加通用变频器硬件基础上,提出一种具有自适应零点调整的电流反馈型补偿方法。并通过TMS320F2808 DSP芯片实现补偿算法,在5.5 kW异步电机上验证了该补偿算法的有效性。     

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。     

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.     

Predictive Torque Control of Induction Machines Using Immediate Flux Control

This paper proposes a new concept for the control of voltage-source inverter (VSI)-fed induction machines. The method uses a predictive algorithm and can be split into two parts. The purpose of the first part, i.e., predictive torque control (PTC), is to predict the stator reference flux vector corresponding to the reference torque at the end of the sampling interval. The second part of the method provides accurate tracing of the stator reference flux by selecting either an active or a zero voltage vector. This approach is called immediate flux control (IFC), where two possible variants are suggested. In the first variant, a simple and fast algorithm obtains minimal stator flux error by impressing either an active or a zero voltage vector throughout the entire sampling interval. Consequently, the switching frequency becomes very low, but current and torque ripple are considerable. The second IFC variant generates the stator flux more accurately by applying an active voltage vector only throughout a calculated time slot within a sampling interval, whereas, during the remaining time of the sampling interval, a zero voltage vector is impressed. As a result, higher switching frequency arises, but it is still lower than that with space vector modulation. Both IFC variants, together with PTC, require minimal processing time and were efficiently implemented in a digital signal processor, which controlled a 3-kW induction machine drive. The obtained experimental results confirm the validity of the proposed approach.     

Online adaptive parameter identification of PMSM based on the dead-time compensation

This paper presents a method of online identification of the parameters of permanent magnet synchronous motors (PMSM) by model reference adaptive identification based on Popov Super Stability Theory. Firstly, the relations of parameters in the Field Orientation Control (FOC) system are analysed. Secondly, the proposed identification method of PMSM concerns two parts. In the case of high-speed operation of the motor, the method can accurately identify the inductance in dq-axis and the permanent magnet (PM) flux linkage. On the other hand, in the case of low speed, it can accurately identify the winding resistance of the stator. The method does not require additional excitation signals, but only makes use of motor voltage, current and their deviations. Thirdly, a simple and effective dead-time compensation method has been applied to inhibit the dead-time effects on the parameter identification. At last, the simulation and experiment results clearly demonstrate the validity and feasibility of the method.     

电网故障时双馈风力发电机励磁改进控制策略

双馈风力发电机（DFIG）在风能捕获过程中,传统的定子磁链定向控制都假定电网上的电压恒定不变,定子磁链也恒定不变,没有考虑定子励磁电流的动态响应过程,这个误差在电网故障时会对系统产生极不稳定的作用。为此应考虑该响应过程,对控制檳型进行修正,提出一种应对电网电压跌落时的励磁改迸策略,即在建立转子侧变换器控制模型时,把反映励磁电流过渡过程的定子电压变化量考虑进来。通过推导定子磁场定向下的转子电压方程,搭建定子磁链定向矢量控制模型,经过仿真结果比较,说明在加入励磁补偿电压项后,风电系统在应对电网电压故障时的电流控制性能得到明显改善,有效提升了系统的低电压穿越能力。     

Direct method of overmodulation with integrated closed loop stator flux vector control

Overmodulation achieves full utilization of installed dc link voltage, by modifying the magnitude and the phase of reference voltage vector. Due to the nonlinear behavior in this region, closed loop vector control becomes difficult. A simple method of overmodulation with closed loop control of stator flux vector is proposed in this paper. Instead of modifying the voltage reference by nonlinear equations or look up table, we propose a direct method to generate the switching times. In so doing, the average angular velocity of the stator flux vector is controlled linearly throughout the modulation range. The proposed method shows lower harmonic distortion compared with existing methods. It greatly reduces the complexity and cost of achieving overmodulation over existing schemes.     

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.     

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...     

Current controller reduced switching frequency for VS-PWM inverterused with AC motor drive applications

The current control system of the three-phase voltage source inverter used in AC motor drive application is presented in the paper. This system, operating in the rotating reference frame fixed to the motor flux, minimizes the switching frequency inverter transistors. The optimal inverter output voltage vector positions, recorded in an electrically programmable read-only memory, ensure the longest path of moving the stator current vector inside the tolerance band which is square shaped. Theoretical bases for the choice of optimal inverter output voltage vector positions are discussed     

Implementation of a direct control algorithm for induction motorsbased on discrete space vector modulation

The basic concept of direct torque control of induction machines is investigated in order to emphasize the effects produced by a given voltage vector on stator flux and torque variations. The low number of voltage vectors which can be applied to the machine using the basic DTC scheme may cause undesired torque and current ripple. An improvement of the drive performance can be obtained using a new DTC algorithm based on the application of the space vector modulation (SVM) for prefixed time intervals. In this way a sort of discrete space vector modulation (DSVM) is introduced. Numerical simulations and experimental tests have been carried out to validate the proposed method     

Dead-Time Elimination for Voltage Source Inverters

A novel dead-time elimination method is presented in this paper for voltage source inverters. This method is based on decomposing of a generic phase-leg into two basic switching cells, which are configured with a controllable switch in series with an uncontrollable diode. Therefore, dead-time is not needed. In comparison to using expensive current sensors, this method precisely determines the load current direction by detecting which anti-parallel diode conducts in a phase-leg. A low-cost diode-conduction detector is developed to measure the operating state of the anti-parallel diode. In comparison with complicated compensators, this method features simple logic and flexible implementation. This method significantly reduces the output distortion and regains the output RMS value. The principle of the proposed dead-time elimination method is described in detail. Simulation and experimental results are given to demonstrate the validity and features of this new method.