A nonlinear speed observer for permanent-magnet synchronous motors. - Teck Seng Low; Tong Heng Lee; Kuan-Teck Chang (IEEE Trans. Ind. Electron., 1993)

An optimal speed controller for permanent-magnet synchronous motor drives. - Kuan-Teck Chang; Teck Seng Low; Tong Heng Lee (IEEE Trans. Ind. Electron., 1994)