A novel V/f control method for speed sensorless
induction motor drives is proposed in this paper. Compared
with constant V/f method, three kinds of compensation are
added: stator resistance compensation, slip frequency
compensation and oscillation suppression compensation.
Based on the vector theory, the stator resistance
compensation is used to keep the stator flux constant in d
axis in steady state, and a low pass filter is adopted to reduce
the influence on dynamic performance of the drive system.
When the stator flux keeps constant in d axis, the equation
for precise slip frequency calculation is simplified. Besides,
the novel oscillation suppression compensation is proposed
based on fast convergence rate of the drive system in a wide
operation region. The proposed compensation is achieved by
feeding both d-axis and q-axis dynamic current to frequency
with different feedback parameters. In addition, the linear
model of this proposed system is derived and analyzed to
design proper feedback parameters. Moreover, the parameter
sensitivities are well analyzed. The proposed V/f controlled
method improves system’s accuracy at the expense of
parameter sensitivities, as the IM’s parameters are used.