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This paper proposes a novel simple reactive power control strategy for the active load balancer (ALB) in three-phase four-wire distribution systems. The proposed reactive power control strategy may be applicable for adjustment of the source-side power factor under the balanced load condition. Only dc capacitor voltage control is used in the proposed control strategy. Therefore, the calculation blocks of the active and reactive components of the load currents are not necessary. The authors, thus, offer the simplest control strategy to control reactive power under the balanced load condition on three-phase four-wire distribution feeders. The basic principle of dc-capacitor-voltage-control-based reactive power control strategy is discussed in detail and then confirmed by digital computer simulation. A prototype experimental system was constructed and tested. Experimental results demonstrate that balanced source currents with reactive power control are achieved on three-phase four-wire distribution feeders. These experimental results also demonstrate that controlling the reactive power reduces the required power rating of the ALB compared with that of the conventional unity power factor control strategy. [ABSTRACT FROM PUBLISHER]

In this paper, we propose a new control algorithm to reduce the capacity of a previously proposed smart charger for electric vehicles (EVs) on single-phase three-wire distribution feeders with reactive power control. The basic principle of the proposed control algorithm is discussed in detail. It is shown that controlling the reactive power on the source side reduces the capacity of the previously proposed smart charger. A digital computer simulation is implemented to confirm the validity of the proposed control algorithm using PSIM software. A prototype experimental model is also constructed and tested. Experimental results demonstrate that balanced source currents with a power factor of 0.9, which is acceptable for Japanese home appliances, are obtained on the secondary side of the pole-mounted distribution transformer during both the battery charging and discharging operations in EVs. The capacity of dc capacitor CDC is also reduced by 37% with the proposed reactive power control algorithm. [ABSTRACT FROM AUTHOR]

This paper proposes a novel active power quality compensator (APQC) topology with a DC voltage balancer for electrified railways. The APQC is composed of a three-leg structure with two common DC capacitors. Two legs perform as two half-bridge inverters, which compensate the unbalanced active, reactive, and harmonic currents on the source side in the traction substation. The third leg controls two common DC capacitor voltages with a small amount of the output currents. Therefore, the current rating of the third leg can be reduced as compared to that of the already proposed three-leg structured APQC. In the control algorithm of the two half-bridge inverters, a strategy based on constant DC capacitor voltage control is used, which does not need any calculation blocks of the unbalanced active, reactive, and harmonic components of the load current to perform the APQC operation. Thus we offer the simplest algorithm for the proposed APQC. The basic principle of the proposed APQC topology with the DC voltage balancer is discussed in detail, and then confirmed by digital computer simulation using the PSIM software. A prototype experimental model is constructed and tested. Experimental results demonstrate that the proposed APQC can achieve balanced and sinusoidal source currents on the primary side of the Scott transformer in traction substations for electrified railways. © 2013 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

In this paper, we propose a single inductor type resonant AC link snubber as a technique for introducing soft-switching PWM technology into three-phase voltage source inverters and explain its circuit operation. We then explain the suitability of instantaneous space voltage vector sinewave modulation compared to sinewave-triangle wave relative modulation as the sinewave modulation technique of the soft-switching inverter introducing this resonant AC link snubber, and propose a time sharing pulse pattern based on the operating principle of this resonant AC link snubber. Furthermore, we discuss the limits on the widths of the pulses that can be output when the time sharing pulse output method is used and the soft-switching inverter performs sinewave modulation, and the need to correct narrow output pulse widths; describe in detail the relationship between the generation principle of the correction pulse pattern and the waveform distortion; and illustrate the simulation results when the minimum pulse width is corrected. Finally, we propose a new time sharing pulse pattern that does not need the minimum pulse width correction by using the time sharing pulse pattern feature for the resonant AC link inverter and demonstrate its effectiveness from the simulation results for this output pulse pattern. © 2004 Wiley Periodicals, Inc. Electron Comm Jpn Pt 1, 88(2): 34–40, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecja.20144 [ABSTRACT FROM AUTHOR]

Electric-field coupling wireless power transfer has been commonly analyzed using the circuit model. However, the circuit behavior of this model is not necessarily apparent because their resonant modes can be far complicated than the basic LC oscillation. This issue is addressed in this paper by proposing a novel equivalent circuit for a basic wireless power transfer system. This equivalent circuit has a simpler topology than the conventional circuit model. Furthermore, the equivalent circuit allows intuitive understanding of three types of the resonant modes. Along with theoretical derivation of the proposed equivalent circuit, this paper also presents simulation results, which verified the appropriateness of the equivalent circuit. © 2015 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]