Study of a New Strategy for Pneumatic Actuator System Energy Efficiency Improvement via the Scroll Expander Technology

Although pneumatic actuators have been widely used in industry and other application areas, its weakness in low-energy efficiency is well known. Aiming for energy efficiency improvement, this paper presents a new hybrid pneumatic system that will recover energy from the exhaust compressed air through a scroll expander. The scroll expander drives a generator to convert the exhaust compressed air energy to electrical energy; thus, the proposed system is entitled “pneumatic-electrical” system. A closed-loop coordinate control strategy is engaged and proven to be essential in maintaining proper actuator operation status, while the scroll expander is connected in. The overall system mathematical model is derived and simulation results are presented in this paper. A test rig is set up to verify the feasibility of the proposed system structure. Both simulation and test results indicate that the proposed scheme is realistic and work well.