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Praveen R.P.,Cochin University of Science and Technology | Ravichandran M.H.,ISRO Inertial Systems Unit | Sadasivan Achari V.T.,ISRO Inertial Systems Unit | Jagathy Raj V.P.,Cochin University of Science and Technology | And 2 more authors.
Transactions on Electrical Engineering, Electronics, and Communications | Year: 2011

This paper presents the optimal design of a surface mounted permanent magnet Brushless DC motor (PMBLDC) meant for spacecraft applications. The spacecraft applications requires the choice of a torques motor with high torque density, minimum cogging torque, better positional stability and high torque to inertia ratio. Performance of two types of machine configurations viz Slotted PMBLDC and Slotless PMBLDC with halbach array are compared with the help of analytical and FE methods. It is found that unlike a Slotted PMBLDC motor, the Slotless type with halbach array develops zero cogging torque without reduction in the developed torque. Moreover, the machine being coreless provides high torque to inertia ratio and zero magnetic stiction. Source


Praveen R.P.,Cochin University of Science and Technology | Ravichandran M.H.,ISRO Inertial Systems Unit | Sadasivan Achari V.T.,ISRO Inertial Systems Unit | Jagathy Raj V.P.,Cochin University of Science and Technology | And 2 more authors.
19th International Conference on Electrical Machines, ICEM 2010 | Year: 2010

This paper presents the design and analysis of a novel machine family-Enclosed Rotor Radial flux Halbach array Permanent Magnet Brushless DC motor (PMBLDC) for spacecraft applications. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the halbach array in the machine was optimized using FE to obtain near trapezoidal flux pattern. Enclosed Rotor Halbach array motor configuration is found to deliver high torque density, high efficiency, zero cogging torque, better positional stability, high torque to inertia ratio and zero magnetic stiction suiting space requirements. The machine provides uniform air gap flux density along the radius thus avoiding circulating currents in stator conductors and hence reducing torque ripple. ©2010 IEEE. Source


Praveen R.P.,Cochin University of Science and Technology | Ravichandran M.H.,ISRO Inertial Systems Unit | Sadasivan Achari V.T.,ISRO Inertial Systems Unit | Jagathy Raj V.P.,Cochin University of Science and Technology | And 2 more authors.
2010 IEEE International Conference on Communication Control and Computing Technologies, ICCCCT 2010 | Year: 2010

This paper presents the design and analysis of a novel machine family of Slotless Permanent Magnet Brushless DC motors (PMBLDC) for precise positioning applications of spacecrafts. Initial design, selection of major parameters and air gap magnetic flux density are estimated using the analytical model of the machine. The proportion of the halbach array in the machine was optimized using FE to obtain near trapezoidal flux pattern. The novel machine topology is found to deliver high torque density, high efficiency, zero cogging torque, better positional stability, high torque to inertia ratio and zero magnetic stiction suiting space requirements. The machine provides uniform air gap flux density along the radius thus avoiding circulating currents in stator conductors and hence reducing torque ripple. ©2010 IEEE. Source


Praveen R.P.,Cochin University of Science and Technology | Ravichandran M.H.,ISRO Inertial Systems Unit | Achari V.T.S.,ISRO Inertial Systems Unit | Raj V.P.J.,Cochin University of Science and Technology | And 3 more authors.
2011 International Conference on Emerging Trends in Electrical and Computer Technology, ICETECT 2011 | Year: 2011

This paper presents the optimal design of a surface mounted permanent-magnet (PM) Brushless direct-current (BLDC) motor meant for spacecraft applications. The spacecraft applications requires the choice of a motor with high torque density, minimum cogging torque, better positional stability and high torque to inertia ratio. Performance of two types of machine configurations viz Slotted PMBLDC and Slotless PMBLDC with Halbach array are compared with the help of analytical and finite element (FE) methods. It is found that unlike a Slotted PMBLDC motor, the Slotless type with Halbach array develops zero cogging torque without reduction in the developed torque. Moreover, the machine being coreless provides high torque to inertia ratio and zero magnetic stiction. © 2011 IEEE. Source


Praveen R.P.,Cochin University of Science and Technology | Ravichandran M.H.,ISRO Inertial Systems Unit | Sadasivan Achari V.T.,ISRO Inertial Systems Unit | Jagathy Raj V.P.,Cochin University of Science and Technology | And 2 more authors.
International Review of Electrical Engineering | Year: 2010

This paper presents the design, analysis and development of a 400-step hybrid stepper motor for actuating the gimbal of a Control Moment Gyroscope (CMG). The design of the hybrid stepper motor for achieving a specific performance requires the choice of appropriate tooth geometry. In this paper, a detailed account of the results of two-dimensional finite-element (FE) analysis conducted with different tooth width/tooth pitch ratios (t/λ) and also with different tooth/slot shapes such as square and trapezoidal, is presented. The use of equal t/λ ratio on stator and rotor provides nearly 10% more torque than the case with unequal t/λ ratio, but with corresponding increase in detent torque and distorted static torque profile. The hybrid stepper motor for actuating the gimbal of a CMG requires maximum torque density, less-detent torque or cogging torque, better positional accuracy and smooth static torque profile. For the said requirements different pitch slotting with equal tooth width has to be provided. The magnitude of the cogging torque has almost been reduced to 50% from what it was while employing equal t/λ configuration. From the various FE models subjected to analysis, trapezoidal teeth configuration with unequal tooth pitch on the stator and rotor is found to be the best configuration and is selected for fabrication. The designed motor is fabricated and the experimental results are compared with the FE results. © 2010 Praise Worthy Prize S.r.l. - All rights reserved. Source

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