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.

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.

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.

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.

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。

特高压直流输电技术发展现状与思考

随着国家能源清洁低碳转型和新型电力系统加快建设,针对未来沙戈荒地区新能源和西部水电基地高效汇集与可靠外送,提升电网支撑能力,适应直流集中接入地区可靠运行等发展需求,结合功率半导体器件技术进步,新型换流设备创新研究与应用实践情况,对不同路线换流器的直流输电技术在系统适应性、可行性、可靠性和经济性等方面开展对比分析。首先,分析了特高压直流输电技术发展需求,总结了直流换流技术最新进展;然后,从应用场景、可靠性、系统支撑能力、技术成熟度等方面,进行了各类换流技术对比,并开展特高压直流新技术风险分析探讨;最后,从确定技术路线、选择设计方案方面提出了特高压直流方案选择要求,并给出直流换流技术发展建议。

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。

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.

提高储能换流器电压及功角暂态特性研究

为提高储能换流器电压及功角暂态特性,对有功电流-频率、无功电流-电压下垂控制进行改进,提出一种根据输出电压有效值变化率表征下垂系数,根据电压调节量自适应调节下垂系数的无功电流下垂控制策略。引入滞环控制在储能换流器电流自适应有功电流-频率下垂控制中,通过滞环控制器将功角维持在一定范围内,确保当电网电压跌落故障时,储能系统功角稳定。Matlab/Simulink仿真和RTDS实验结果表明:所提新型控制方案可以提高储能对系统惯性无功支撑能力,提高储能控制系统对电压暂态波动的抑制能力,有效提升了储能换流器输出电压及功角暂态性能。

一种补偿谐波电流的无刷双馈电机转矩脉动抑制方法

针对无刷双馈电机存在较强转矩脉动的问题,根据旋转坐标系下电流与转矩之间的关系,明确了功率绕组电流中含有的谐波分量会导致电机运行时产生转矩脉动的结论,提出以谐波补偿电流的方式抵消电机运行时产生的谐波分量来抑制无刷双馈电动机转矩脉动,采取了功率绕组谐波电流瞬时检测方法与空间矢量滞环控制方法来满足系统对实时性和准确性的要求。该转矩脉动抑制方法能有效提高无刷双馈电机的机械特性和调速性能,对于降低无刷双馈电机绕组谐波含量提高整机效率提供了参考。最后以一台45 kW的绕线转子无刷双馈电机为例进行了验证,通过对谐波电流补偿法在电机异步、同步以及超同步运行状态下的仿真对比分析,结果表明该方法可有效抑制电机的谐波转矩脉动,提高电机运行性能。

开关磁阻电机低速运行无位置传感器检测方法

针对开关磁阻电机低速运行方法中的传统脉冲注入法只利用非导通相电流信息,存在导通区间受限和续流影响估计精度的问题。本文对低速控制策略与无位置检测原理进行研究,提出了一种双电流斩波限PWM滞环控制的三相电流斜率差值无位置传感器检测方案。所提方案在导通区采用双斩波限PWM滞环控制,使导通区电流斩波次数增加,能够改善低速运行时的性能,并提高电流斜率差值的计算精度。与传统非导通相电流比较方法只利用非导通相信息相比,该方案增加了导通相电流计算。在计算导通相电流斜率差值后,与两非导通相形成三相电流斜率差值,从而估计电机的实时位置信息。以三相12/8结构的电机进行了相关仿真和实验验证,实验结果表明,该方案能够有效解决传统方法存在的导通区间固定和实时角度计算受续流影响的问题。

基于离散域改进PIR控制的PMSM电流谐波抑制策略

在表贴式永磁同步电机(PMSM)矢量控制系统中,固定的比例积分谐振(PIR)控制器参数会在运行工况变化时导致电流谐波抑制效果变差,为此,提出一种改进的离散域控制器参数设计方法。首先,通过频率特性曲线对比加入谐振控制器后电流环幅频响应,分析连续域谐振参数整定方法的局限性。其次,推导离散域谐振数字控制器表达式,并给出离散域电流环稳定性证明过程。最后,以调制比为约束条件,构建满足系统稳定的离线谐振增益切换表。为解决谐振增益稳定切换的问题,采用滞环控制算法实现谐振增益在不同转速区间的平滑切换。最终,通过仿真和实验结果可知,基于离线切换表的改进比例积分谐振控制器在不同转速工况时,既满足了系统的稳定性,又实现了抑制5、7次电流谐波的效果。

An Improvement in Power Quality and By-Product of the Run-Off River Micro Hydro Power Plant

Utilization of Micro Hydro Power Plant at the Gunung Halu case study type run-off the river is a household use only in the afternoon,around 5 pm until bedtime at about 10 pm.Therefore,more than 75%of the energy is lost.This case study lost power which can be used as a by-product,such as for drying coffee beans.In this case study,a design was carried out to obtain by-products and improve power quality in the electrical system.In addition,they complain about the poor quality of power controlled by frequency using Triac-Based Electronic Dummy Load Control.The heat from the dummy load in the case study is used as a by-product.MHP with a minimum power of 20 kW,and the usage time of customer service is about 6 h.The energy for the by-products is about 360 kWh/day,and the power quality improved by using Triac-Based Electronic Load Control and Hysteresis Current Control for the active filter.As a result,the power factor is close to one,the generator current harmonics is less than 2%,and the voltage harmonics is less than 5%.

降低永磁同步电机滞环控制电流波动的方法研究

针对PMSM滞环电流控制(Hysteresis Current Control,HCC)电流波动问题,提出了一种采用电压计算来降低电流波动的方法。当电流在磁滞的误差范围内时,输出不连续积分的d,q轴电压,仅在不需要电流变化时积分器进行积分。经过适当的计算,电机电流将在误差范围内直接跟踪给定值,电流的稳态波动较小,不受误差大小的影响。同时指出了数字迟滞计算方法中的PWM输出延迟问题,根据三相电压的耦合关系和PWM波形的中心对称性,提出了一种执行延迟补偿策略,该补偿方法对系统参数和测量噪声不敏感。仿真和试验测试验证了所提出的控制策略。

电磁式馈能悬架系统的建模及控制策略研究

针对悬架主动控制高能耗的问题,研究了双向AC/DC变换器的双波段滞环电流控制器,并提出了一种电磁式馈能悬架半主动控制系统。建立了悬架的机-电耦合模型,基于电流控制器和天棚算法设计了馈能减振控制电路,理论推导了电流控制器的电流波纹系数和开关周期,理论分析和仿真表明其有快速高精度的电流跟踪能力。此外,仿真表明,该耦合模型能描述相对位移、感应电动势和电流随负载电阻变化的合理变化趋势。该半主动控制系统能采集和存储振动能量,并利用存储的能量调节电阻尼力抑制悬架振动,具有低能耗减振特性。

Optimized Power Factor Correction for High Speed Switched Reluctance Motor

The Power Factor Correction(PFC)in Switched Reluctance(SR)motor is discussed in this article.The SR motors are applicable for multiple applications like electric vehicles,wind mills,machineries etc.The doubly salient structure of SR motor causes the occurrence of torque ripples,which affects the power factor of the motor.To improve the power quality,the power factor has to be corrected and the ripples have to be minimized.In order to achieve these objectives,a novel power factor correction(PFC)method is proposed in this work.Here,the conventional Diode Bridge Rectifier(DBR)is replaced by a Bridgeless Hybrid Resonant(HR)converter,which assists in improvising the output in a wider range.The converter is chosen because of having variety of beneficial measures including high gain.The converter’s output is fed to the SR motor by means of an asymmetric Bridge Resonant(BR)converter.The proposed converter operates in continuous mode of conduction with the switching frequency of 10 KHz.A hysteresis current controller and Proportional Integral(PI)controller are utilized for reducing the harmonics in the source current along with the regulation of output voltage.In addition,the speed control of SR motor is accomplished by means of the Whale Optimization Algorithm(WOA)assisted PI controller.The proposed methodology is effective for the control of unity power factor,torque and current ripples.The Total Harmonic Distortion(THD)of the source current is also minimized,which suits the standard of International Electrotechnical Comission IEC 61000-3-2.By this methodology,the power factor of 0.99 is achieved with 97%efficiency and 3.92%THD.The proposed methodology is validated in simulation by MATLAB and in hardware by FPGA Spartan 6E.