Patent ID: 7560894

Claim:
A method in connection with a speed and position sensorless permanent magnet synchronous machine equipped with an output filter and driven by an inverter, wherein the method comprises the steps of forming a speed-adaptive full-order observer based on the dynamic model of the combination of the permanent magnet synchronous machine (PMSM) and the output filter, the observer using inverter output current (i A ) as the measured feedback signal and an estimate for the electrical angular speed ({circumflex over (ω)} m ) of the motor and a speed correction term (ω ε ) for adaptation of the observer, measuring the inverter output current (i A ), estimating inverter output current (î A ) using the observer, determining the estimate for the electrical angular speed ({circumflex over (ω)} m ) of the machine using the estimated inverter output current (î A ) and measured inverter output current (i A ) in an adaptation law, injecting a voltage signal (u c ) into the inverter voltage reference (u A,ref 0 ) to obtain a modified voltage reference (u A,ref ) that is used to control of the inverter, detecting an error signal (ε) from the measured inverter output current (i A ) originating from the injected voltage signal (u c ), and calculating the speed correction term (ω ε ) used in the adaptation of the observer from the error signal (ε).