Active Pressure Pulsation Suppression Method by Parallel-Series Structure in DFCU Based on Variable Step Size FXLMS Algorithm

Abstract

Pressure pulsation is the challenge in digital hydraulics owing to its switching characteristics, which makes control performance worse. This study proposed the parallel-series structure for active pressure pulsation suppression, based on variable step size FXLMS algorithm. The pressure pulsation performance in DFCU is analyzed under PNM and PWM control for better suppression effect. On this basis, the active pressure pulsation suppression control algorithm is designed utilizing the principle of pressure wave destructive interference, so that the reverse pressure pulsation generated by the parallel-series structure, including an in-series valve arranged in line between the DFCU and the load and a by-pass valve arranged in parallel with DFCU, offsets with the pressure pulsation at the load end. The adaptive FXLMS algorithm with variable step size is used to identify the secondary path online for better effect of pressure pulsation suppression and achieve the “alignment” between the reverse pressure signal and the initial pressure signal. The experimental results show it can suppress pressure pulsation by 79%, 54%, 37% and 29% at 10 Hz, 30 Hz, 50 Hz, 70 Hz for single valve and 77% for DFCU. It has been demonstrated that the proposed structure has significant effect and guiding relevance for pressure pulsation suppression of DFCU.