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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]

Electric motors used for irrigation applications contribute to a major part of worldwide energy demand. Efficiency improvement of motors used in these applications is the need of the hour. Usually, line-start (LS) induction motors are used in these applications. However, they are relatively inefficient compared to permanent magnet (PM) motors. On the other hand, PM motors have high initial cost compared to induction motors. In view of this, magnet-less machines like synchronous reluctance motors (SyRM) and PM assisted SyRM are being preferred. SyRM has poor power factor compared to induction motor and hence PM assisted SyRMs are becoming popular. In this article, a 2-pole multi-barrier LS ferrite assisted SyRM is proposed for a bore-well submersible water pump. Two-pole rotor geometry is not extensively studied for LS SyRMs. Further, the issues of ferrite magnet demagnetization for 2-pole LS applications are not explored. A separate cage is avoided by utilizing the rotor flux barriers as a cage, thereby reducing the number of ribs while housing the magnets. This improves the power factor and efficiency of proposed motor. Analytical and finite element analysis (FEA) are used for design of the proposed motor. Further, a prototype is fabricated and experimental results are presented. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) powered submersible electric water pumps are becoming popular in remote rural areas, due to the nonavailability of grid connectivity. However, the initial cost of a PV system is high. Permanent magnet (PM) brushless dc (BLDC) motors are efficient compared to existing induction motors, which reduce the cost of PV array. However, steep increase in the cost of rare-earth magnets like NdFeB and SmCo makes the use of PM motor uneconomical for PV systems. Thus, the design of PM motors with ferrite magnets is gaining interest. These magnets have low remanence flux density and are brittle. Thus, flux concentration rotor topologies are desirable. The conventional spoke-type (ST) rotor is one such topology. However, flux leakage is one of its prime concerns. To negotiate this, a novel “semi-modular dual-stack” ST BLDC motor along with its parametric aided three-dimensional finite element method analysis is proposed for a PV-based 100 mm deep bore-well submersible water pump. The motor features minimum flux leakage irrespective of rotor bridge width. In addition, a lumped parameter thermal network is modeled for quick estimation of the winding temperature rise. A prototype motor is fabricated to ascertain the results obtained from simulations, and the experimental results are presented. [ABSTRACT FROM PUBLISHER]

Cross magnetization (CM) is an inevitable phenomenon in electrical machines. It is more prominent in interior permanent magnet (IPM) brushless dc (BLDC) machines. This is because PMs demagnetize in overloaded and saturated conditions. It leads to cross coupling between the direct and quadrature-axes quantities, and a decrease in the resultant air-gap flux-density distribution under saturated conditions. In this paper, it is shown that CM leads to braking torque even in unsaturated IPM BLDC machines. Furthermore, the effect of CM on flux linkage, electromotive force, and dynamic torque is presented. Its mitigation using suitable selection of slot–pole combination is presented. It is observed that odd slot–pole combinations are least affected, and even slot–pole combinations are severely affected by CM. Furthermore, it is found that the overlap area of rotor pole arc with the stator pole arc influences the severity of CM, more particularly in fractional slot–pole combination machines. To verify these claims, finite-element method is used for modeling and analyzing various slot–pole combinations of a spoke-type IPM BLDC motor. The results obtained from these simulations are validated with a fabricated reference prototype, which support 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]