Shin-Kuan Chen

Modeling characteristics of harmonic currents generated by high-speed railway traction drive converters

This paper presents a study for modeling harmonic currents injected by three-level pulse-width-modulated (PWM) converters of the high-speed railway traction drive in steady-state motoring mode. An analytical solution for converter harmonics based on the double Fourier series theory is described. The time-domain simulation results obtained by the use of PSpice are then compared with those obtained by the proposed model. It is shown that the harmonic currents determined according to the proposed model agree well with those results obtained by using the time-domain simulation tool.

An analytical approach for characterizing harmonic and interharmonic currents generated by VSI-fed adjustable speed drives

Applications of solid-state converters for adjustable speed drives (ASDs) are popular in industrial systems. The ac/dc/ac conversion system, frequently used to provide ac voltages with adjustable frequency/magnitude in the ASDs, consists of a voltage source inverter (VSI) fed by a three-phase diode-bridge rectifier, which generates significant amount of line harmonic and interharmonic currents into the supply system and may cause undesired effects on other power system components. This paper presents an analytical approach for characterizing the current harmonics and interharmonics of the VSI-fed ASD injected into the supply system in steady state, where the circuit models for the rectifier, the dc link, the PWM inverter, and the ac motor are considered in the analysis. The accuracy of the results obtained by the proposed model is demonstrated by comparing with those obtained by using the time-domain simulation tool, Simulink of Matlab, and by laboratory tests. It is shown that the proposed approach is effective to characterize current harmonics and interharmonics generated by the ASD, while the solution accuracy and the computational efficiency are still maintained.

Accurate Assessment of Harmonic and Interharmonic Currents Generated by VSI-Fed Drives Under Unbalanced Supply Voltages

Applications of solid-state converters and inverters for adjustable speed drives (ASDs) are popular in industrial systems and lead to a significant amount of harmonic and interharmonic currents being injected into the connected system. This paper presents an accurate analytical approach for the assessment of the harmonic and interharmonic currents generated by the voltage-source inverter-fed ASDs operated under unbalanced supply voltages, where the commutaton effect of the ASD converter and the detailed motor circuit model with various load levels are included. To validate the accuracy of the proposed approach, simulation results are performed by comparing those obtained by a time-domain simulation tool and by laboratory tests. It is shown that the proposed method can effectively calculate the harmonic and interharmonic currents produced by the ASD, either under balanced or unbalanced supply-voltage conditions.

An efficient a–b–c reference frame-based compensation strategy for three-phase active power filter control

Abstract The active power filter has been proved to be an effective method to mitigate harmonic currents generated by nonlinear loads as well as to compensate reactive power. In the implementation of a three-phase active power filter, it is crucial to have a procedure (i.e. the compensation strategy) to generate the reference compensation currents by its control circuit. This paper proposes a simple and efficient a – b – c reference frame-based strategy to determine the reference compensation currents for both three-phase three-wire and three-phase four-wire active power filters. Simulation and experimental results show that the proposed compensation strategy yields a simpler design of the control circuit than those obtained by using the conventional instantaneous reactive power theory (i.e. p – q theory). A competitive active filter performance is also achieved.

An a-b-c Reference Frame-Based Compensation Strategy for Series Active Power Filter Control

This paper presents a new control strategy to determine the reference compensation voltages of a series active power filter (APF) operated under non-ideal supply voltages in the steady state. With using the proposed control strategy, the load-side voltages can be maintained being sinusoidal and balanced. The effectiveness of the proposed control strategy is demonstrated through simulations by using Pspice. Results show that the expected series APF performances are achieved with adopting the new control strategy

Modelling VSI-Fed ASDs by Matlab/Simulink for harmonic and interharmonic assessment

This paper presents simulation results by using Matlab/Simulink for the assessment of harmonic and interharmonic currents generated by the voltage source inverter (VSI)-fed adjustable speed drives (ASDs). In the simulation, the commutation effects caused by source impedance and non-ideal supply voltages are included. The front-end converter, dc link, pulse-width modulated (PWM) inverter, and the induction moter of the ASD are modeled in detail. Results are then compared with those obtained by laboratory tests to show the solution accuracy. Numerical and measurement experiences show that the adopted simulation tool yields satisfactory results for harmonic and interharmonic current assessments of VSI-fed ASDs.

Harmonic-domain modeling of fluorescent lamp with electromagnetic ballast

This paper presents a harmonic-domain method for modeling currents generated by traditional fluorescent lamp with electromagnetic ballast Both the nonlinearity of lamp components and the effect of source voltage distortion on the lamp are taken into account in the proposed model. Simulation results based on the described method are compared with those obtained from experimental tests. It is found that the solutions obtained based on the proposed model agree very well with the experimental test results.

A new instantaneous power theory-based three-phase active power filter

The active power filter has been proved to be an effective device to mitigate harmonic current and/or voltage distortions produced by nonlinear loads as well as to compensate reactive power. In the past some active power filters were designed based on the conventional instantaneous reactive power (IRP) theory. However, these types of filters can only compensate reactive power for the load. If the load generates harmonic current or is unbalanced, the conventional IRP theory-based active filter cannot compensate the harmonic distortion and does not function properly. In order to overcome the drawbacks of the conventional IRP theory, a new instantaneous power theory-based algorithm is proposed for the control strategy of the active filter. In this paper the implementation of a 10 kVA prototype active power filter which is developed based on the proposed control algorithm is present. Simulation and experimental results with varied source and load conditions are described to confirm that the new proposed control strategy achieves better performance for the active power filter than those obtained by using conventional IRP control strategies.

Temporal hand gesture recognition by fuzzified TSK-type recurrent fuzzy network

Temporal hand gesture recognition by fuzzified Takagi-Sugeno-Kang (TSK)-type recurrent fuzzy network (FTRFN) is proposed in this paper. The temporal hand gesture is captured by CCD and represented by a two-dimensional fuzzy trajectory. To handle fuzzy trajectories, FTRFN is employed. The inputs and outputs of FTRFN are fuzzy patterns represented by Gaussian membership functions, and the recurrent property of FTRFN enables it to deal with fuzzy patterns with temporal context. In recognition scheme, the FTRFN performs trajectory recognition by prediction instead of classification. Experiments on ten categories of gestures are performed to verify the proposed approach.

Skin color segmentation by histogram-based neural fuzzy network

Skin color image segmentation by a histogram-based self-constructing neural fuzzy inference network (SONFIN) is proposed in this paper. Each color pixel is represented by a hue-saturation (HS) space. To represent a block color by histogram as accurately as possible, a nonuniform quantization approach of HS space is considered. Histogram information of HS from images under different environments is used to train SONFIN to make the method as robust as possible. To verify performance of the proposed method, experiment on human-hand segmentation is performed. For comparison, other segmentation methods are applied to the same problem.