Search

To meet the new international efficiency (IE) standards, line-start (LS) synchronous reluctance motors (SyRMs) are now being considered. Conventional star and delta windings are usually employed in LS SyRMs. However, combined star-delta winding has higher winding factor and lower magneto-motive force (mmf) harmonics compared to conventional star and delta windings. Hence, in this paper, LS SyRM and LS ferrite assisted SyRM with star and star-delta winding are analyzed and their performance indices are compared. A winding function analysis is used for the design of star and star-delta windings. Further, the effect of zero sequence current on the performance of the motors under comparison is presented in detail. Star and star-delta winding prototype LS SyRMs with and without ferrite magnets in the rotor are fabricated. Experimental studies are carried-out on these prototypes and the results are presented which are in close agreement with the simulation results. [ABSTRACT FROM AUTHOR]

A modular multiport converter (MMPC), which is capable of interfacing multiple solar Photo-Voltaic (PV) modules, a battery bank, and a dc microgrid, is proposed in this article. The number of solar PV modules that can be interfaced with the proposed MMPC is equal to the number of converter modules present in the system. Furthermore, all these solar PV modules can operate at their respective maximum power point, thus increasing the power extraction capability. A high-frequency transformer facilitates the interfacing of low-voltage solar PV modules and the battery bank with a 380-V microgrid. However, the power from the solar PV modules to the battery bank does not flow through this transformer. The variation in the transformer utilization with changes in operating voltages of the solar PV modules is analyzed. Detailed simulation studies are carried out on a system having five solar PV modules to verify the performance of the proposed MMPC. A laboratory prototype of the proposed MMPC consisting of four numbers of 400-W converter modules is fabricated. The performance of the MMPC is analyzed and the experimental results are presented. [ABSTRACT FROM AUTHOR]

This article proposes a solid-state transformer (SST) based power electronic architecture for fast charging three categories of plug-in electric vehicle with batteries of vastly different voltage and power ratings. The SST accomplishes integration to a medium-voltage grid and isolation to the charging ports without the use of an LFT. Delta connected cascaded H-bridge (CHB) is used as the active front-end rectifier and quad active bridges (QABs) are utilized for the isolated dc–dc conversion stage. In the proposed architecture, an additional winding called balancing winding is provided in each of the medium-frequency transformers of the QAB. The balancing winding of the transformers are paralleled such that a circulating current flows among the transformers of the three phases, which eventually reduces the unbalance in the delta-connected clusters. Hence, the magnitude of zero-sequence current required to balance the cluster powers for a certain level of unbalance is also reduced. As a result, the total current in the devices of the CHB decreases and devices with a lesser current rating can be used. The control philosophy and detailed analysis of the system are given in the article. Experimental results with a scaled-down prototype are presented to verify the claims. [ABSTRACT FROM AUTHOR]

Switched reluctance motors (SRM) are becoming attractive due to the increasing cost of permanent magnets. It was reported that segmented rotor construction improves the torque output and efficiency of SRM. This paper investigates the effect of stator slot/rotor segment combination and number of phases on the performance of segmented rotor SRM (SSRM). It is found that SSRMs having higher number of rotor segments than stator slots have high efficiency and torque output, but they also have limitations of narrow speed range and low overload capability. On the other hand, it is found that SSRMs with higher number of both stator slots and rotor poles have high overload capability. The effect of increasing number of phases of SSRM is also evaluated. It is found that a polyphase SSRM improves the torque output, but does not have the limitations of low overload capability and narrow speed range. Thus, the choice of stator slot/rotor segment combination and number of phases depends largely on application. Procedure to select stator slot/rotor pole combination and number of phases of SSRM is presented here. Experimental results supporting conclusions from analysis are also given. [ABSTRACT FROM AUTHOR]

A motor for in-wheel electric vehicle (EV) requires high efficiency and specific torque. In view of this, permanent-magnet brushless dc (PM BLDC) motor is most commonly employed for this application. However, due to the increasing cost of PMs, machines that do not use PMs are attracting interest. Switched reluctance motor (SRM), with its simple and robust construction, along with fault tolerant operation, is a viable option for in-wheel EV application. However, the SRM has low specific torque as compared with BLDC. Therefore, design improvements are required to make SRM a viable alternative to BLDC motor. In this paper, a new 12/26 pole SRM with high specific torque is proposed for in-wheel EV application. This machine has segmented-rotor-type construction. Also, concentrated-winding arrangement is used, ensuring low end-winding volume and copper loss. The developed machine also has high efficiency. In order to verify the design, the prototype of the machine is fabricated, and experimental results are presented. [ABSTRACT FROM AUTHOR]

A three-phase three-level dc-to-dc phase-shifted pulsewidth-modulation (PSPWM) converter which is reported in the literature for high-power and high-input-voltage applications is based on a three-phase three-wire configuration. However, the controllable duty cycle range of the aforementioned converter is 0– 2\pi/3. Therefore, to obtain the rated voltage, the converter needs to be overrated by 33%. In order to overcome this problem, a modified topology of the three-level dc-to-dc PSPWM converter based on a three-phase four-wire configuration is proposed. The soft switching of devices is achieved by using a tapped filter inductor. The output voltage is controlled by incorporating PSPWM. The clocked gate signals of each leg are phase shifted by 2\pi/3 from each other. Major features of the converter include the following: 1) The outer two switches of each leg are operating as zero-voltage switch; 2) the inner two switches of each leg are operating as zero-current switch; and 3) this is achieved without involving any extra passive or active components. Realization of the secondary output filter by having a tapped inductor leads to considerable reduction in circulating current flow during a freewheeling period and results in appreciable mitigation in conduction losses. In order to obtain the behavioral and performance characteristics of the converter topology, analytical and simulation studies are carried out, and the viability of the scheme is ascertained through detailed experimental studies. [ABSTRACT FROM AUTHOR]

This paper proposes a concept of fictitious “Electrical Gear” to analyze the flux pattern in the three-phase flux-reversal machine (FRM). The rotating-flux pattern of FRM has either two or four poles depending on the number of stator poles. FRM can be analyzed on similar lines as permanent magnet synchronous machine with the concept of this gear. The flux-density distribution in FRM is analyzed with Fourier analysis. The magnitude of various space harmonics and their contribution to the winding-flux linkages are determined. The procedure for finding the rms value of air-gap flux density from machine dimensions is described. In order to verify the aforementioned analysis, a 6/14 pole FRM with distributed and concentrated windings is designed and fabricated. The experimental results are compared with those obtained from finite-element method simulation studies and analytical results. [ABSTRACT FROM AUTHOR]