A method and apparatus provide a
state observer control system 600 for a motor 106 that uses an
extended Kalman filter 330 to predict initial rotor position and afterwards accurately predict rotor position and / or speed under variable types of loading conditions. A
control system model 300 is generated that allows variable setting of an initial rotor position to generate estimated rotor position and speed as outputs. The
control system model 300 includes an EKF (
extended Kalman filter) estimator 330, speed controller 322, a current controller 324, and a
variable load component 310. During operation, EKF estimator 330 estimates
rotor speed 327 and position 333 based on reference voltages 402, 404 and currents 1325 generated by speed and current controllers 322, 324 and input from frame transformers 326, 328. Additionally, the reference currents and voltages 402, 404, 1325 are frame-transformed to be used as feedback signals 418, 346 in the
system 600 and as drive signals to
control power to be applied to a
motor load 602.