Development of Smooth and High Torque Drive for Space Applications
- Paper number
IAC-07-D1.1.01
- Author
Mr. P.Murali Krishna, Indian Space Research Organisation (ISRO), India
- Coauthor
- Year
2007
- Abstract
High performance spacecrafts demands their rotating mechanisms to be disturbance free and smooth torque. Brushless DC motors are best suited for such applications due to their linear characteristics, smooth control of speed and torque. But the standard motors produce parasitic torque pulsations and the torque ripples due to fringing fields or the errors in excitation currents. They lead to speed oscillations, vibrations and control difficulty especially at low speed and loads. The disturbance torque affects not only the concerned mechanism but also the spacecraft control system. The torque compensation scheme is usually used which may not be perfect.
A high torque coreless motor is designed and developed at ISRO for a low speed mechanism Dual Gimbal Antenna (DGA). The core less armature design eliminates the magnetic disturbance torques but the major penalty with coreless configuration is very low torque capability and critical fabrication and assembly process. Though the coreless design is a known concept, it requires design optimization, utmost care and precision assembly procedure which prevented its usage for ripple free and high torque applications.
The BLDC motor is designed with an air core armature to achieve zero cogging, zero hysterisis drag and zero decentering forces. Two phase winding with continuous commutation is used to achieve the ripple free output torque. Dual pole magnetic circuit is used to obtain higher air gap field. Special fixtures are used for precision assembly of BLDC motor components. The challenging task is to generate higher torque and to provide mechanical strength for the core less armature. For the same output torque the power requirement is less than 50% of the standard core motor and the response is 7 times faster. The uncertainty in the level of compensation which otherwise required for slotted core motor is totally eliminated. The qualification of the motor is being carried out and it proposed to use for all future DGA type applications namely CARTOSAT-2B and CHANDRAYAAN-I. This paper describes the design, development and test results of coreless brushless DC motor developed for low speed high torque applications.
- Abstract document
- Manuscript document
IAC-07-D1.1.01.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.