In HAPF fundamental and harmonic voltages transmit energy to active part leading to the energy pulsation and dc-side voltage fluctuation. In order to solve the problem， inverter's electric and mathematical model are established and analyzed. An improved PI controller adopting on-line self-adjustment technique of proportional control and recursive integral control is proposed to regulate the active part absorbing or releasing active power. It is proposed that the inverter is controlled to produce restraining current through detecting fluctuation current in injecting branch. Energy pulsation can be restrained by using the above two methods. Finally the combination of the above methods with current control method to obtain the total reference signal is given in detail. Experiment results show that the method can restrain the energy pulsation， stabilize the dc-side voltage， and improve the performance of the system.