Patent ID: 8653768

Claim:
A method for calculating the flux in a rotating electrical machine which is electrically supplied by an inverter, the method comprising: determining an inverter voltage vector (u x1 , u y1 ); determining an inverter current vector (i x1 , i y1 ); calculating an estimated flux vector as (ψ S — EST ) based on the inverter voltage vector and the inverter current vector; comparing a length of the estimated flux vector with a reference flux magnitude (ψ S — REF ); and compensating for errors by changing the length of the estimated flux vector (ψ S — EST ), depending on the comparison of the length of the estimated flux vector (ψ S — EST ) with the reference flux magnitude (ψ S — REF ), wherein a compensated flux offset vector (ψ OFF — COMPENSATE ) is added to a resistive voltage loss integral (ω N ·Ts1·r S — EST ·{right arrow over (i S )}[k]), and the estimated flux vector (ψ S — EST ) is calculated according to the following equation {right arrow over (ψ)} S — EST [k]={right arrow over (ψ)} S — EST — PRELIMINARY [k ]−(ω N ·Ts 1 ·r S — EST ·{right arrow over (i)} S [k]+{right arrow over (ψ)} OFF — COMPENSATE [k ]).