An active filter that uses a high-frequency D-class asynchronous switching inverter for power system current distortion compensation is described. The distortion compensation technique involves deriving a signal corresponding to the distortion component of load current, and inverting and amplifying this signal for addition back to the supply current to cancel the load current distortion. A synthetic sinusoid is used to determine the distortion component in the time domain. Extensive computed and experimental results, illustrating the system’s steadystate performance and ability to reduce the current harmonic distortion components, are presented. An intelligent controller is proposed to maintain the active filter’s performance at the optimal operating point under varying load conditions.