In this paper, the observer based on the flux estimation method is presented. There are reduced-order and full-order types in flux
observers based on the flux estimation. Reduced-order flux observers have a simple structure and short calculation time. However,
they have drawbacks which comes from noise and disturbance. Therefore, full-order flux observers are used in this paper.
Conventional full-order flux observers are methods that use an estimated d- and q-axis currents in the flux estimation.
Nevertheless, the gain that includes the speed information of the denominator has a problem of deteriorating performance since
the magnitude of the gain value largely increases in the low speed range. To control the speed precisely at both low- and high-
speed ranges, the proposed full-order flux observer uses the improved gain. The improved gain has a stable estimation performance
in both low- and high-speed range. This paper verifies the excellence of the proposed algorithm by using the improved full-order
flux observer that has stable estimation performance through the simulation.