Field-Oriented Control for Performance Improvement in Reaction Wheels and Implementation of Algorithm in FPGA

Abstract

The reaction wheels play a major role in attitude control of the spacecraft. As they work on the principle of conservation of angular momentum, any ripple in reaction torque will affect the performance of critical on-board instruments such as atomic clock, high-resolution cameras, etc. in the spacecraft. The three-axis stabilization system using reaction wheels aims to provide high-pointing accuracy, low jitter and long-term attitude stability. The stringent attitude and micro-vibration requirement of future missions cannot be met practically with the existing reaction wheels with conventional trapezoidal brushless direct current motor (BLDC) drive. A suitable upgrade in reaction wheels with permanent magnet synchronous motor (PMSM) instead of BLDC motor and field-oriented control instead of six-step commutation will be enabled to meet these requirements. Improvements in torque ripple will give additional benefit in losses and hence lesser load on thermal system. This study investigates the possible usage of PMSM and field-oriented control for future generation reaction wheels and its implementation in FPGA. Simulation results showed improved steady-state performance in terms of torque ripple without any degradation in the transient response of the wheels. The study can be well extended to gimbal control of CMG and other high-precision servo applications in the spacecraft.