Generally, tracking controller is used to guarantee desired currents. We propose the nonlinear tracking controller. Lyapunov based controller is needed to improve
the current tracking performance. When the Lyapunov
based controller is used, the current feedback is need.
Since measured currents have high frequency noises such
as switching noise of pulse width modulation (PWM)
of motor driver and electromagnetic interference noise,
the conventional LPFs are used to filter out the high frequency noises. However, when the LPFs are used, phase
lag in the currents is appeared. To remedy this problem,
we propose the current FLPFs as follows