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PWM逆变器死区效应的检测与补偿 总被引:4,自引:0,他引:4
本文对PWM电压型逆变器的死区效应提出了一种实时补偿方法,设计了电流瞬时值过零点的检测方法,该方法简单易行,可适用于变压变频调速系统中。 相似文献
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三相逆变器中包含了一些开关器件,具有很强的非线性,在建立其状态空间模型时,很难得出它的解析解,介绍了一种用准状态空间方程的方法,比较精确地建立了三相逆变器的数学模型。并在MATLAB/SIMULINK中仿真了电磁暂态和状态空间近似模型,仿真结果验证了提出的模型是精确和有效的。 相似文献
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A repetitive voltage compensation technique that generates a high-quality sinusoidal output voltage from a single-phase pulse width modulation (PWM) inverter used for uninterruptible power supplies is described. A repetitive control technique eliminates the steady-state error in the distorted output voltage caused by cyclic loads. The proposed PWM inverter system uses microprocessor-based closed-loop digital feedback with a sinusoidal reference. The PWM pattern is determined at every sampling instant by the proposed algorithm, implemented by a microprocessor using a set of detected output voltages and the reference signals through one cycle. The system has low distortion and very fast response for AC phase-controlled loads 相似文献
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The authors have already described the nine-phase inverter driving system providing both the triple three-phase voltage source inverter with 180-deg conducting period and the ac motor windings with triple three-phase construction. The nine-pulse inverter driving system used three small-capacity three-phase coupling reactors having special windings for current balance and reduction of higher harmonics. In addition, for voltage control, current balance, and waveform improvement, optimal PWM pulse patterns were applied to the six-phase inverter driving system using a three-phase coupling reactor to provide double three-phase construction. In the system based on the mode in the title, the PWM control was applied to the nine-phase inverter driving system described in the foregoing. The coupling reactors in the system balance the fundamental currents of three sets of three-phase inverters and also absorb higher harmonic voltages other than 18p±1 (p = 1, 2, …) orders. The optimal pulse patterns found by the approach to make the performance index minimum using the Lagrange multiplier method can be applied to the PWM to reduce the higher harmonic currents greater than those calculated by the modulation method comparing the sinusoidal signal wave with triangular carrier signal. This system can have a larger capacity than the six-phase PWM inverter driving system in which coupling reactors absorb higher harmonic voltages other than the 12p±1 orders and also improve output current waveforms. In addition, the system includes the capacity of coupling reactors slightly larger than the six-phase PWM inverter driving system but enables operation with smaller torque ripples and electromagnetic noises in low- to high-frequency ranges. 相似文献
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Variable frequency inverter with sinusoidal voltage outputs using rotating coordinate transformation
Hirotami Nakano Masayuki Jibiki Akira Nabae Yositsugu Okamura 《Electrical Engineering in Japan》1997,118(4):94-102
An ideal inverter should have sinusoidal voltage and current outputs. Generally, output voltages of a voltage-source PWM inverter contain high-level switching frequency harmonies due to the PWM operation, while output currents are kept nearly sinusoidal. High-level harmonics contained in output voltages of a voltage-source inverter cause acoustic noises, iron losses and electromagnetic interferences. An LC filter was used to suppress the switching frequency harmonics; however, there is a danger of resonance in the LC filter. Accordingly, to remove harmonics of the LC filter resonance frequency, the authors add a voltage feedback loop. A conventional system can operate without difficulty within 50 Hz. However, with accompanying increases in the output frequency, output voltages are largely delayed and reduced by a high-pass filter inserted in the feedback loop. These problems are caused by a high-pass filter inserted in the feedback loop. Accompanied by the inverter output frequency, a high-pass filter cannot remove the fundamental component perfectly. As a result, a small fundamental component is fed back, which causes a delay and decrease in output voltage. This paper proposes the application of coordinate transformation to a high-pass filter inserted in the feedback loop. As a result, the proposed system realizes an ideal filter which can suppress fundamental frequency components perfectly, and improves the characteristics of the inverter with sinusoidal voltage outputs greatly. Theoretical analyses, simulations and experiments showed satisfactory results. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 118 (4): 94–102, 1997 相似文献
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Modeling of motor bearing currents in PWM inverter drives 总被引:1,自引:0,他引:1
Shaotang Chen Lipo T.A. Fitzgerald D. 《Industry Applications, IEEE Transactions on》1996,32(6):1365-1370
Pulse-width modulated (PWM) inverters have recently been found to be a major cause of motor bearing failures in inverter-fed motor drive systems. Specifically, all inverters generate common-mode voltages relative to the earth ground. These voltages provide coupling or bearing currents through motor parasitic capacitances to the rotor iron which flow via the bearings to the grounded stator case. In this paper, a model of bearing currents caused by PWM inverters is proposed. The model is based on transmission line theory which uses an equivalent lumped parameter π-network to describe the parasitic coupling phenomenon. The model parameters are then identified by matching the calculated model outputs with those of experimental measurement. The validation of the method is demonstrated by the fact that the model can reproduce a variety of experimental results obtained on a test motor. An application of this method also gives a motor grounding current model. As the conducted electromagnetic interference (EMI) in motor drive systems is related to the grounding currents, the grounding current model can be used for the analysis of conducted EMI in motor-drive systems 相似文献
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单相五电平逆变器的多载波PWM方法分析 总被引:1,自引:0,他引:1
针对单相五电平级联逆变器,对不同的多载波PWM方法进行分析。采用载波移相(PS)PWM方式时,其输出波形中含有幅值较大的高次谐波,而载波垂直分布(CD)PWM方式不存在这些问题,但是CDPWM调制方式的低次谐波比较大。与CDPWM调制方式相比,采用PSPWM调制方式所产生的低次谐波分量非常小。结合2种PWM调制方式各自的优点,提出一种混合多载波PWM方法。通过对典型的五电平PWM单相逆变电路的Matlab仿真计算,证明了混合多载波PWM法输出波形中的高次谐波含量小,低次谐波分量介于PSPWM调制方式和CDPWM调制方式之间,总的谐波畸变率最小。因此,对于单相的五电平逆变器而言,混合调制方式为最优。 相似文献