Patent ID: 8723459
Filing Date: 2014-05-13
Classification: H02P

Abstract:
1. A method of controlling a sensorless permanent magnet synchronous machine using a frequency converter connected to feed the machine with electrical power, the method comprising: producing a current vector having a magnitude to a stator of the machine with the frequency converter; and rotating the current vector for rotating a rotor of the machine, wherein the method further comprises: prior to starting a drive of the machine, defining a value for the magnitude of the current vector and a frequency limit; using the defined value as the magnitude of the current vector when the rotor of the machine is rotated with a frequency that is lower than the defined frequency limit; and using a vector control method for controlling the machine when the frequency of the machine is higher than or equal, or below to the defined frequency limit, wherein the vector control method includes: providing a signal proportional to a torque of the machine; amplifying the signal proportional to the torque and feeding the amplified signal to a controller for obtaining a speed compensation term; subtracting the speed compensation term from an estimated speed obtained from a vector control algorithm for obtaining a corrected speed estimate; using the corrected speed estimate in a motor model for obtaining a stator current estimate; calculating a stator current error as a difference between a measured stator current and the estimated stator current; and estimating a speed of the machine from the stator current error for correcting an orientation of an estimate of a rotor angular position.