Control techniques for active power filters

Several options exist for the control of reactive power and distortion control in power systems using active power filters. The error sawtooth based systems can be enhanced to give regular switching patterns with minimized harmonics for steady state operation. Co-ordinated three phase hysteretic control can approach the steady state performance of optimized waveforms but with improved performance in transients. For high power high frequency operation, series or parallel connection of inverters can yield a high effective switch rate but the algorithms available to date are the regular sampled versions: error-sawtooth and sampled error. All the algorithms can be modified to account for the existence of system resonances more easily than passive filter banks