Improved hysteresis circle current control method for active power filter

Hysteresis circle current control method with variable circle width of shunt active power filter not only ensures tracking accuracy of reference current, but controls switching frequency of inverter effectively through adjusting hysteresis circle width real-timely according to current amplitude. Traditional hysteresis circle current control method with variable circle width was improved through adding a fine-tuning link of circle width. When switching frequency of the inverter is low, calculated circle width value is reduced by adding a negative fine-tuning value. The Matlab simulation results show that total harmoic distortion of the system is 1.80% when harmonic current is tracked and compensated by use of the improved method, which is less than the value by use of the traditional method, and actual switching frequency of the inverter is more close to set value.