Modeling and Optimization of a Linear Electromagnetic Piston Pump

Transcription

1 Fluid Power Innovation & Research Conference Minneapolis, MN October 10 12, 2016 ing and Optimization of a Linear Electromagnetic Piston Pump Paul Hogan, MS Student Mechanical Engineering, University of Minnesota Advisor: Dr. James Van de Ven October 12, 2016

2 Agenda Guiding question: What is the most direct means of converting stored electrical energy to hydraulic energy? 2

3 Motivation Hydraulic actuation for human-scale power applications (< 1 kw) Mobile applications, robotics, prostheses Electrical storage has superior energy density, hydraulic actuators have superior power density Applications require efficient and compact energy conversion 3

4 Issue: Multiple Energy Conversions Typical electric-to-hydraulic energy conversion at humanscale power requires modularization: Electric motor Shaft coupling Hydraulic pump Simplify by converting electric energy directly to linear piston motion Image: PSM-Hydraulics 4

5 Direct Energy Conversion Electrical Energy Linear Mechanical Energy Hydraulic Energy Linear electromagnetic actuators convert stored electrical energy directly into linear mechanical energy 5

6 Piezoelectric Piston Pumps High forces (70 kn) High frequencies (400 Hz) Challenges with friction, inertia, and valve resonances Image: Henderson et al. (2013). 6

7 Linear Diaphragm Pumps Low noise High reliability Low power output (0.3 lpm, 12.8 psi) Image: GD-Thomas LMF Series 7

8 Objectives Reduce complexity of electrical-to-hydraulic energy conversion Fewer energy conversions: increased efficiency Fewer moving parts: increased reliability Fewer components: decreased package volume 8

9 Linear Electromagnetic Piston Pump HP Manifold Piston X X X LP Manifold Displacement controlled with current and driving frequency 9

10 Coupled Construction Goal: computationally inexpensive with reasonable accuracy Magnetic Equivalent Circuit (MEC) Flow of magnetic flux analogous to electrical current Piston Dynamics the motion of the piston Pressure Dynamics the pressure within each cylinder 10

11 Validation Parameter ed FEA Error dx = 0 mm dx = 5 mm dx = 0 mm Cycle Power Density Cycle Efficiency 344 N 351 N -2.0% 247 N 262 N -5.7% H H 3.4% 0.19 W/cc 0.18 W/cc 1.8% % 11

12 Genetic Optimization Multiple objectives: Power density: cycle output power package volume Efficiency: P out P out + P drag + P leak + P loss,act Comparison: 1.5 hp electric motor (w/o coupling or hydraulic motor) ~0.2 W/cc 10 stator poles 6 stator poles 4 stator poles 12

13 Conclusions More stator poles, larger piston diameters, lower frequencies are associated with higher efficiencies Fewer poles, smaller diameters, higher frequencies give higher power densities Higher power densities and efficiencies than stateof-art are achievable 13

14 Acknowledgments Dr. Eric Severson, post-doctoral researcher in Electrical Engineering at University of Minnesota Minnesota Supercomputing Institute (MSI) at the University of Minnesota 14

15 validation and proof of concept with experimental linear electromagnetic actuator coupled to piston heads Looking for: Expertise in manufacturing of linear actuators Off-the-shelf linear actuator of similar design Check valves capable of operation at Hz 15

16 References Henderson et al. The Influence of Passive Valve Characteristics on the Performance of a Piezo Pump. (2013). 16