Position linearisation scheme for permanent magnet synchronous motor drive of washing machine using low-resolution hall sensors

Variable speed systems have been widely applied to home appliances. One of the applications is vector control scheme of a washing machine using low-resolution hall sensors. Vector controller with binary-type hall sensors is cost effective. However, due to electrical and mechanical non-uniformity related to hall sensors, the position obtained by hall sensors does not change linearly, and resultant bumps in the position information degrade control performance. To solve this problem, a new position observer that generates linearly changing position signal is proposed. The proposed scheme removes necessity of knowing mechanical parameters and additional calculation process by utilising a Kalman filter for speed detection. The feasibility and effectiveness of the proposed algorithm are verified through experimental results carried out with a washing machine.