共查询到19条相似文献,搜索用时 78 毫秒
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本文首先论述了三电平逆变器SVPWM的原理,利用最近三角形合成规则,推导了三角形定点矢量的作用时间。在此基础上,提出了一种通过判断中点电容电位而合理选择和分配小矢量的无电流传感器的中点电位控制方法,并作了具体阐述。理论分析和实验结果证明了此方法的有效性。 相似文献
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简要的介绍了三电平逆变器电压空间矢量法实现过程,重点考虑了三点平逆变器中点电位平衡控制问题,设计控制策略,解决中点电位的漂移问题,通过MATLAB/simulinkf仿真对结果做出分析。 相似文献
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一种新型的三电平变频器中点电位平衡控制方法 总被引:2,自引:0,他引:2
中点电位不平衡问题一直是二极管箝位三电平逆变器固有的问题。本文提出了一种新的结构模式和中点电位控制算法。它用三电平整流器代替了传统的三相桥式不控整流装置,通过对三电平整流器的控制来解决三电平逆变器所产生的中点电位平衡问题,同时达到了提高功率因数和减少电网网侧谐波的效果。这将是一种应用前途非常广泛的模式。 相似文献
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由三电平有源前端(AFE)和三电平逆变器构成的中高压变频器在能量再生,功率因数,输入和输出谐波方面具有良好的性能.在这种变频器中,为了实现直流侧中点电位平衡控制(NPB),以往的方法都要对逆变控制采用的SVPWM算法进行调整,这不可避免地会增加逆变输出谐波.本文提出一种无需调整SVPWM算法而只在变频器前端解决NPB问题的策略,避免了逆变输出谐波的增加,使负载电机旋转磁场具有较为理想的圆度.文中介绍了这种NPB的基本原理,对在前端控制与在逆变侧控制的输入和输出性能进行了比较分析.仿真实验研究结果证明了该控制策略的正确性和有效性. 相似文献
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This paper proposes a novel switching method with the neutral-point voltage control in a single-phase neutral-point-clamped three-level inverter (SP-NPCI) used in photovoltaic systems. A proposed novel switching method for the SP-NPCI improves the efficiency. The main concept is to fix the switching state of one leg. As a result, the switching loss decreases and the total efficiency is improved. In addition, it enables the maximum power-point-tracking operation to be performed by applying the proposed neutral-point voltage control algorithm. This control is implemented by modifying the reference signal. Simulation and experimental results provide verification of the performance of a novel switching method with the neutral-point voltage control. 相似文献
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Jung-Min Kwon 《International Journal of Electronics》2013,100(3):419-433
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. 相似文献
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Muhammad Jamil 《International Journal of Electronics》2013,100(12):1293-1303
This article presents carrier-based modulation strategies for a neutral point clamped inverter that substantially reduces harmonics in the output line to line voltages, phase voltages, reference voltages and common mode voltage. A graphical technique that has already been proposed in the literature and that also allows various carrier disposition modulation strategies for a diode clamped inverter is being described here. For this graphical technique two new modulation strategies – alternative phase opposite disposition (APOD) and phase disposition (PD) – are being used to create reduced harmonics for diode-clamped inverters under both continuous and discontinuous switching conditions. These strategies can be further expanded in a very simple way. A comparison of conventional-, APOD- and PD-strategies will be given by simulation results by using the software ‘Simplorer’ and ‘Post Processor Day’. The common mode voltage has been reduced particularly with PD-strategy. The strategies have been confirmed using a three level inverter for medium voltage. 相似文献
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为了更好地在电网运行中加强GIS设备高压试验,首先必须对试验流程进行分析,并对其危险点进行分析,并加强对其的控制,才能更好地确保高压试验质量,进而更好地促进其性能的发挥。 相似文献
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近年来,变电站设备因遭受雷击或输电线路雷电侵入波而导致绝缘损坏的事故时有发生,由于雷电冲击传递过电压将对二次绕组绝缘耐受电压造成很大的威胁,因此,在电压互感器二次回路中性点就地安装过电压保护措施具有重要的意义。本文对电压互感器二次中性点安装过电压保护的必要性进行分析研究。 相似文献
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本文结合电网的整体结构、中性点消弧补偿方式与中性点偏移的数学关系,进一步改进了消弧设备的感性电流注入方式,采取了一系列措施来抑制中性点电压的过大偏移情况。 相似文献
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This paper presents a direct model-based predictive control scheme for voltage source inverters (VSIs) with reduced common-mode voltages (CMVs). The developed method directly finds optimal vectors without using repetitive calculation of a cost function. To adjust output currents with the CMVs in the range of –Vdc/6 to +Vdc/6, the developed method uses voltage vectors, as finite control resources, excluding zero voltage vectors which produce the CMVs in the VSI within ±Vdc/2. In a model-based predictive control (MPC), not using zero voltage vectors increases the output current ripples and the current errors. To alleviate these problems, the developed method uses two non-zero voltage vectors in one sampling step. In addition, the voltage vectors scheduled to be used are directly selected at every sampling step once the developed method calculates the future reference voltage vector, saving the efforts of repeatedly calculating the cost function. And the two non-zero voltage vectors are optimally allocated to make the output current approach the reference current as close as possible. Thus, low CMV, rapid current-following capability and sufficient output current ripple performance are attained by the developed method. The results of a simulation and an experiment verify the effectiveness of the developed method. 相似文献
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This article suggests a robust cascade speed control algorithm for a permanent magnet synchronous motor (PMSM) combining the classical feedback linearising (FL) method and the disturbance observers (DOBs) without the integrators. The contributions of this method are twofold. The first one is to provide the simple DOBs for not only guaranteeing the closed-loop performance recovery property but also removing the steady-state errors without the integrators with respect to the tracking errors. The second one is to prove that the inner and outer loops are stabilised by the proposed cascade-type controller, simultaneously. The simulation and experimental results reveal that the proposed method maintains the speed tracking performance to be satisfactory for a wide operating region with the fixed control gain despite a plant-model mismatch where a 3-kW interior PMSM is utilised. 相似文献