Designing Reaction Wheels for Nanosatellite Applications with the use of GaN Inverters

Abstract

The reaction wheel module (RWM) designed in this work is composed of three main parts: Brushless DC motor, a 3-phase inverter, and flywheel. This work summarizes all the necessary background information to design a RWM for controlling nanosatellites. The 3-phase inverter designed is based on GaN MOSFETS, which are considered wide band-gap semiconductor devices because they have a relatively large band-gap compared to conventional Si semiconductors. Key advantages of wide band-gap semiconductors over typical semiconductors are their high dielectric strength, high operating temperature, high current density, high switching-speed, and low on-resistance. These characteristics enable GaN-based inverters to operate at higher switching frequencies which leads to component miniaturization and improved output voltage quality. An initial laboratory setup was developed to test and validate the performance of GaN-based inverters and compare it with that of Si-based inverters. The RWM design also included motor selection and the flywheel sizing. The motor selected is a high-speed BLDC motor with high power density and high torque. The flywheel design is of a simple disk and ring shape. The dimensions of the flywheel where selected using a stochastic approach, where the optimal size was found using an Optimization Genetic Algorithm.

Date of Award	Jul 2019
Original language	American English
Supervisor	Prashanth Marpu (Supervisor)