AN ALGORITHM FOR THE OUTPUT WAVEFORM COMPENSATION OF SPWM INVERTERS BASED ON FUZZY-REPETITIVE CONTROL
Duan Shan-Xu - Kang Yong - Chen Jian
An algorithm based on fuzzy-repetitive control for the output waveform compensation of single-phase CVCF inverters is presented.
The performance of CVCF inverters is evaluated in terms of output voltage waveform distortion with linear or nonlinear
loads and transient response due
to sudden changes in the load. The fuzzy PD controller is used to improve transient performance whenever the system exhibits
an oscillatory or
overshoot behavior. It preserves the simple linear structure of the conventional PD controller yet enhances its self-tuning
control capability. Since
fuzzy PD controller cannot provide good small-signal response, repetitive control is applied to generate high-quality
sinusoidal output voltage in
steady state. Repetitive control can be regarded as a simple learning control because the control input is calculated
using the information of the
error signal in the preceding periods. The repetitive controller is synthesizing to minimize low-order harmonic distortion.
Thus, the fuzzy PD
controller and repetitive controller can be combined to take advantage of their positive attributes. The control scheme
is implemented based on DSP
in a 400Hz 5.5kW prototype. Simulation and experimental results prove that the proposed control scheme can achieve not only
low THD during
steady-state operation but also fast transient response subject to load step change.
Keywords: fuzzy control, inverter, repetitive control