
Control of Converter-Fed Induction Motor Drives 21-21
However, in a very-low-speed operation, the eect of inverter nonlinearities (dead time, DC link voltage
pulsations, and power semiconductor’s voltage drop) has to be compensated.
21.6.2.3.2 Rotor Flux Vector Estimator
When the stator ux vector, Ψ
s
, is known, the rotor ux vector can be easily calculated as
Ψ Ψ σ
αr
r
m
s s s
L
L
L= −
( )
α α
I
(21.50a)
Ψ Ψ
r
r
m
s s s
L
L
L
β β β
σ= −
(
)
I
(21.50b)
e above equations are represented in Figure 21.14 as block diagrams in stationary α–β coordinates.
ere are many other methods for rotor ux estimation based on speed or position measurement.
Also, the observer tech ...