RELIABLE HYSTERESIS CURRENT CONTROLLED DUAL BUCK HALF BRIDGE INVERTER

A highly efficient and re liable topology-dual buck half bridge inverter (DBI) is introduced. The existenc e of discontinuous conduction mode (DCM) operation state requires the bias of in du ctor current for DBI implemented with linear controllers like ramp comparison SP WM (RCSPWM) controllers. A novel operation scheme for DBI and a hysteresis curre nt controlled dual buck half bridge inverter (HCDBI) are proposed. The bias curr ent required by RCSPWM DBI is eliminated and conduction losses are dramatically reduced. HCDBI has greatly improved the modulation performance in DCM region for the benefit of its excellent command tracking capability. The operational schem e and control strategy are presented. Power losses of the conventional half brid ge inverter (CHBI) and HCDBI are compared with mathematical computation, and exp erimental verification is also executed. Both calculational and experimental res ults verify that HCDBI has a superior switching performance over CHBI. Its exce llent high frequency operational capacity provides another access to realize high fre quency operation of inverters.

DSP Based Simulator for Speed Control of the Synchronous Reluctance Motor Using Hysteresis Current Controller

This paper presents the field oriented vector control scheme for synchronous reluctance motor (SRM) drives, where current controller followed by hysteresis comparator is used. The test motor has a star-connected wound stator and a segmental rotor of the multiple barrier type with an external incremental encoder to sense rotor position. The magnetic characteristics of this motor are described using 2D finite element method, which is used firstly for rotor design of SRM. The field oriented vector control, that regulates the speed of the SRM, is provided by a quadrature axis current command developed by the speed controller. The simulation includes all realistic components of the system. This enables the calculation of currents and voltages in different parts of the voltage source inverter (VSI) and motor under transient and steady state conditions. Implementation has been done in MATLAB/Simulink. A study of hysteresis control scheme associated with current controllers has been made. Experimental results of the SRM control using TMS320F24X DSP board are presented. The speed of the SRM is successfully controlled in the constant torque region. Experimental results of closed loop speed control of the SRM are given to verify the proposed scheme.

FPGA Implementation of Predictive Hysteresis Current Control for Grid Connected VSI

Grid connected voltage source inverters (VSIs) are essential for the integration of the distributed energy resources. Hysteresis current control (HCC) is a commonly employed method for power control of VSIs. This control method, in contrast with voltage control, provides good dynamics, good stability and implicit over current protection. However, the most important concern of digital implementation of HCC is related with the sampling period of the measured currents. This paper presents a predictive hysteresis current control (HCC) for grid connected voltage source inverter and its FPGA implementation. Simulation and experimental results are provided to verify the validity of the proposed implementation.

Adaptive Hysteresis Current Vector Control of Synchronous Servo Drives with Different Tolerance Areas

Control methods of hysteresis current vector control of permanent magnet synchronous servo drive fed by voltage source inverter are examined. Detailed description of the control methods in stationary reference frame with circle, square and hexagon shape tolerance area using adaptive solutions is presented. The theoretical considerations are supported by simulation results.

Digital fixed-frequency hysteresis current control of a BLDC motor applied for aerospace electrically powered actuators

In the conventional cascade control structure of aerospace electrically powered actuators, the current（or electromagnetic torque） loop plays a critical role in realizing a rapid response for a digitally controlled Brush Less Direct Current（BLDC） motor. Hysteresis Current Control（HCC） is an effective method in improving the performance of current control for a BLDC motor.Nevertheless, the varying modulating frequency in the traditional HCC causes severe problems on the safety of power devices and the electromagnetic compatibility design. A triangular carrier-based fixed-frequency HCC strategy is expanded by relaxing the constraints on the rising and descending rates of the winding current to advance the capability of HCC to realize fixed-frequency modulation in the steady state. Based on that, a new flexible-bound-size quasi-fixed-frequency HCC is proposed, and the range feasible to realize fixed-frequency modulation control can cover the entire running process in the steady state. Meanwhile, a corresponding digital control strategy is designed,and four digitalization rules are proposed to extend the capacity to achieve fixed-frequency modulation control to the unsteady working state, that is, a novel fixed-frequency modulation is realized.Simulation and experimental results prove the effectiveness of this improved fixed-frequency HCC strategy.

Design of DSTATCOM Controller for Compensating Unbalances

In a three phase power system, the voltages at the generation side are in sinusoidal and equal in magnitude with 120? phase difference between the phases. However, at the load side voltages may become unbalanced due to unequal voltage magnitudes at the fundamental frequency, phase angle deviations or unequal distribution of single phase loads. The voltage unbalance is a major power quality issue, because a small unbalance in the phase voltages can cause a larger unbalance in the phase currents. A completely balanced three-phase three wire system contains only positive sequence components of voltage, current and impedance, whereas unbalanced system contains both positive and negative sequence components of voltages and currents. The negative sequence component of current in the unbalanced system increases the temperature and losses in the equipments. Hence, it is necessary to mitigate this problem by supplying the negative sequence current to the load at the load side and keep the source side balanced. This paper proposes the shunt connected, current injecting Distribution Static Synchronous Compensator (DSTATCOM) with appropriate controller to mitigate the unbalanced load current. The symmetrical components based Hysteresis Current Controller (HCC) is designed for DSTATCOM to diminish the unbalances in a three-phase three-wire system. The performance of the controller is studied by simulating the entire system in the MATLAB/Simulink environment. The DSTATCOM with HCC is found to be better than other controllers because it is suitable for compensating both balanced and unbalanced loads.

Control Strategies for PM Synchronous Machine Controlled Rectifier Intended for Heavy-Duty Vehicle

In order to charge batteries and supply all the electrical devices like wheel-motors used in a heavy-duty hybrid electric vehicle, a solution consists in using an assembly permanent magnet generator driven by a diesel engine and a three-phase insulated gate bipolar transistor/diodes bridge controlled rectifier connected to the battery. In this work, hysteresis current control strategies combined with a judicious current sensing mode for the assembly permanent magnet synchronous machine-controlled rectifier are investigated. Main issues first concern the different kinds of transistors switching modes allowed by the proposed current sensing mode when the machine operates either as a generator or as a motor. Second, the modulated hysteresis method is presented, which merges the performances of robustness and dynamic of the classical hysteresis method and imposes the switching frequency alike pulsewidth modulation techniques. A test bench at reduced power permits to test the switching modes as well as classical and modulated hysteresis methods for both motor and generator operating modes and to validate the simulation predictions. The digital signal processor algorithm elaborated for the control strategy is flexible and adaptable to all kinds of transistor switchings and machine operating modes.

Improved Control in Single Phase Inverter Grid-Tied PV System Using Modified PQ Theory

Grid-connected reactive-load compensation and harmonic control are becoming a central topic as photovoltaic(PV)grid-connected systems diversified.This research aims to produce a high-performance inverter with a fast dynamic response for accurate reference tracking and a low total har-monic distortion(THD)even under nonlinear load applications by improving its control scheme.The proposed system is expected to operate in both stand-alone mode and grid-connected mode.In stand-alone mode,the proposed controller supplies power to critical loads,alternatively during grid-connected mode provide excess energy to the utility.A modified variable step incremental conductance(VS-InCond)algorithm is designed to extract maximum power from PV.Whereas the proposed inverter controller is achieved by using a modified PQ theory with double-band hysteresis current controller(PQ-DBHCC)to produce a reference current based on a decomposition of a single-phase load current.The nonlinear rectifier loads often create significant distortion in the output voltage of single-phase inverters,due to excessive current harmonics in the grid.Therefore,the proposed method generates a close-loop reference current for the switching scheme,hence,minimizing the inverter voltage distortion caused by the excessive grid current harmonics.The simulation findings suggest the proposed control technique can effectively yield more than 97%of power conversion efficiency while suppressing the grid current THD by less than 2%and maintaining the unity power factor at the grid side.The efficacy of the proposed controller is simulated using MATLAB/Simulink.

基于多电平滞环电流控制的牵引供电系统可控宽频带阻抗测量技术

精确获取牵引供电系统的宽频带阻抗特性,是分析车-网耦合系统的宽频带振荡问题的关键途径,对保障电气化铁路的安全稳定运行具有重要意义。目前的阻抗测量技术大多难以兼顾大功率与频带可控的测量要求,因此,该文提出一种基于多电平滞环电流控制的牵引供电系统可控宽频带阻抗测量技术,测量频带为10 Hz~5 kHz,可通过一次谐波扰动注入快速获取目标频带的系统阻抗,相比于传统的滞环电流控制方法,具有更低的开关频率,并且能有效避免死区效应,改善输出电流的波形,更适用于宽频信号的跟踪控制。最后,通过仿真和硬件在环实验验证了该测量技术的有效性。

一种变输入电压的TCM滞环电流逆变器控制方法

针对TCM逆变器在过零点附近因开关频率过高导致并网电流THD和开关损耗增加的问题,提出一种变输入电压的准恒频控制方法。通过控制后级输入电压限制TCM电流源型逆变器的最大开关频率,降低了并网电流的谐波失真率。通过Simulink搭建仿真模型,对并网电流进行FFT分析,结果显示该方法相比传统的TCM调制方法使得并网电流的THD下降了0.02%,验证了所提方案的可行性。

一种基于电压空间矢量的有源滤波器滞环电流控制新方法

为提高有源滤波器的电流跟踪性能,提出一种基于电压空间矢量的滞环电流控制新方法。该方法利用电流误差矢量与参考电压矢量的空间分布给出最佳的电压矢量切换,使电流误差控制在滞环宽度以内;采用电压空间矢量消除相间影响,并且其实现简单,无需复杂的矢量变换。在降低开关频率条件下,既有较好的电流响应速度,又能有效限制电流误差,改善电流跟踪性能。实验结果证明该方法的正确性和可行性。

有源滤波器的电压空间矢量双滞环电流控制新方法

该文提出了一种有源滤波器的电压空间矢量双滞环电流控制新方法。该方法直接在复平面上实施控制,内环选择的开关状态减少高次谐波分量,外环选择的开关状态电流响应速度快,有效限制误差电流,改善滤波器性能;利用逆变器输出电压及其引起的误差变化来判断有源滤波器参考电压矢量所在的区域,简单可靠。电压空间矢量的引入可以提高直流电压利用率,降低开关频率。仿真结果证明了其可行性。

有源滤波器的低损耗滞环电流控制方法

提出一种新的用于有源滤波器的低损耗滞环电流控制方法。利用有源滤波器的输出电流主要是谐波电流,因此在一个周期内总的三相电流绝对值大小波动幅度很大的特点,根据电流大小调节相应的开关次数,从而在保持相同控制精度的同时,大幅降低有源滤波器的开关损耗。在理论上推导了最优开关频率和电流范数波动幅度的关系,设计了一个新的滞环电流控制器。仿真结果表明,采用所提出的方法可在保持总的控制精度的同时有效降低总的开关损耗。

基于最优电压矢量的有源滤波器电流控制新方法

提出了一种新的基于最优电压矢量的有源滤波器滞环电流控制方法。该方法的特点是用一组滞环相间电流比较器和一组阶梯式相间电流比较器相结合，快速、正确地判断有源滤波器参考电压空间矢量所在的区域，并由此决定最优电压矢量及对有源滤波器实行滞环电流控制。用电磁暂态程序进行的计算机仿真结果表明，该方法能快速、正确地确定最优电压矢量，从而可有效地降低开关频率和提高有源滤波器的效率。其突出优点是在参考电压空间矢量变化较快且难以预测的情况下，仍能快速跟踪及确定其所在的区域，从而可有效地减少电流补偿误差，改善有源滤波器的性能。

带中点电位平衡控制的Vienna整流器滞环电流控制方法

针对三相三电平Vienna整流器存在的固有中点电压波动问题,提出将直流侧中点电压偏差引入滞环电流闭环控制中,通过调节指令电流的直流偏移量实现直流侧中点电压平衡控制。结合等效电路分析了Vienna整流器滞环电流工作原理,设计了电压外环控制器,并给出了滞环宽度和中性点补偿系数的选取依据。最后搭建了一台Vienna整流器样机对该方案进行了验证,实验结果验证了该方案的可行性。

一种改进型并联混合有源电力滤波器及其控制

针对并联混合型有源电力滤波器谐波电流注入支路中存在阻塞谐波电流注入的阻抗问题,提出一种改进注入支路的并联混合型有源电力滤波器,使谐波注入支路上不存在影响补偿谐波电流注入电网的阻抗。根据该新型电路结构,通过分析谐波补偿和基波有功电流控制的原理,得出有源部分逆变器输出电压目标值的计算公式,并提出一种新的定频滞环电压控制方法用于控制逆变器输出电压,从而间接地实现了谐波补偿电流和直流侧电容电压的精确控制。最后,通过PSIM仿真实验和物理装置模拟实验验证本文所提新型注入支路和定频滞环控制方法的可行性和有效性。

基于空间矢量双滞环策略的STATCOM直接电流控制方法

提出一种适用于STATCOM的直接电流控制新方法以减小开关频率和电流跟踪误差。该方法通过指令电流求导矩阵替代参考电压预测方法,能够准确判定参考电压矢量的位置,并根据误差电流矢量与双滞环阈值的大小选择优化的开关状态输出。与其它电流控制方法相比,基于空间矢量双滞环策略的直接电流控制方法可以保证无功电流的快速响应性能,同时有效降低开关频率。仿真与实验结果证明其良好的动静态性能。

矩阵变换器电流控制策略

分析了传统矩阵变换器空间矢量调制策略,提出一种新型的矩阵变换器电流控制策略。该控制策略在虚拟整流部分,通过适当选取输入电压可实现高输入功率因数控制;在虚拟逆变部分,在一个采样周期内通过对输出电流进行基于规则的滞环跟踪控制及对虚拟逆变器的合适矢量选择,确保输出电流的误差在一个小的滞环宽度内。新型电流控制策略相比传统的基本滞环控制,减少了输入电流的谐波,改善了矩阵变换器的输入、输出性能。通过Matlab软件仿真分析并搭建Dspace硬件实时仿真平台对所提控制策略进行了实验研究,仿真及实验结果验证了新型电流控制策略的正确性。

三相三线有源电力滤波器滞环电流控制策略

滞环电流控制是三相四线有源电力滤波器(APF)常用的电流控制方法,但在三相三线APF中应用不够成熟。分析了三相三线APF滞环电流控制策略的原理及可行性,给出了滞环控制中关键参数的设计和选择方法。通过对开关模态及三相电流关系的分析,推导出了三相三线APF直流侧电压选择的理论参考公式。在此基础上提出一种基于双数字信号处理器的APF数字滞环电流控制方法,实现了全数字化三相三线APF的滞环电流控制,实验结果证明了该方法的有效性。