Test Bed 1 Energy Efficient Displacement-Controlled Hydraulic Hybrid Excavator

Transcription

1 Test Bed 1 Energy Efficient Displacement-Controlled Hydraulic Hybrid Excavator Enrique Busquets Monika Ivantysynova October 7, 2015 Maha Fluid Power Research Center Purdue University, West Lafayette, IN, USA.

2 Outline Testbed goals Achievements up to date on the prototype Advancements in control development For hydraulic hybrid For power management For pump switching Measurements results Conclusions October 7, 2015 Enrique Busquets 2

3 Testbed Goals Target Achieve 50% fuel savings Maintain or improve machine productivity Metric kg of fuel (tons soil / hour) 50% reduction of rated engine power kw Maintain or improve machine controllability (expert operator evaluation) 50% reduction of cooling power kw October 7, 2015 Enrique Busquets 3

4 Displacement-Controlled (DC) Actuation Energy savings by throttle-less actuation Each actuator requires a hydraulic unit Motion is achieved through unit displacement Energy recovery Low Pressure High Pressure E OVERRUNNING LOADS October 7, 2015 Enrique Busquets 4

5 Testbed Goals Implemented on a Bobcat 435 excavator on 2009 LS Hydraulics DC Hydraulics October 7, 2015 Enrique Busquets 5

6 CAT Productivity Test ~40% Fuel savings 90 truck loading cycle ~70% Productivity increase October 7, 2015 Enrique Busquets 6

7 Cooling Power Study Temperature ( C) One of the underestimated benefits of DC technology is less heat generation In 2010 a preliminary study of the oil temperatures was conducted using a DC excavator prototype DC system temperature with % of nominal cooling power % % 50% % 80 0% o C Simulations showed possible reduction of required cooling power by 50% time (sec) 1) Busquets, E An Investigation of the Cooling Power Requirements for Displacement-Controlled Multi-Actuator Machines. Purdue MS thesis. 2) Zimmerman, J., Busquets, E. and Ivantysynova, M % Fuel Savings by Displacement Control Leads to Lower Working Temperatures - A Simulation Study and Measurements. Proceedings of the 52nd National Conference on Fluid Power 2011, NCFP I October 7, 2015 Enrique Busquets 7

8 Hydraulic Hybrid and DC Actuation Power (kw) 50% possible engine downsizing Rated Power Reduced Power time (s) Stored energy complements engine power Sizing study with 256 different designs determined hydraulic components sizes Parameter Parameter sizes V 1 (cc/rev) V 2 (cc/rev) V 0 (L) p min (bar) ) Zimmerman, J. and Ivantysynova, M Hybrid Displacement Controlled Multi-Actuator Hydraulic Systems. Proceedings of the 12th Scandinavian International Conference on Fluid Power, May , Tampere, Finland, pp October 7, 2015 Enrique Busquets 8

9 Secondary-Controlled Hydraulic Hybrid Formerly focused on constant HP level MEANINGLESS FOR A HYDRAULIC HYBRID Pressure Control Primary unit allows energy storage and transmission to common shaft Secondary unit controls inertia load dynamics Velocity feedback Speed Control October 7, 2015 Enrique Busquets 9

10 Hydraulic Hybrid Actuator-Level Control PI Controller Adaptive Robust Control Pressure is considered a disturbance and controlled using a separate PI controller Robust H Controller 1) Busquets, E. and Ivantysynova, M. Adaptive Robust Motion Control of an Excavator Hydraulic Hybrid Swing Drive. SAE International Journal of Commercial Vehicles, 8(2): , 2015, doi: / SAE COMVEC Congress Technical Paper Selected for Journal Publication. 2) Busquets, E. and Ivantysynova, M A Robust Multi-Input Multi-Output Control Strategy for the Secondary Controlled Hydraulic Hybrid Swing of a Compact Excavator with Variable Accumulator Pressure. Proceedings of the ASME/BATH 2014 Symposium on Fluid Power & Motion Control. Bath, United Kingdom. October 7, 2015 Enrique Busquets 10

11 Measurement Results PI Cabin Position PI Cabin Velocity 0 to ~90 High Inertia H Cabin Position H Cabin Velocity Cabin Position Error ARC Cabin Position ARC Cabin Velocity Cabin Velocity Error October 7, 2015 Enrique Busquets 11

12 Measurement Results PI Cabin Position PI Cabin Velocity 0 to ~180 High Inertia H Cabin Position H Cabin Velocity Cabin Position Error ARC Cabin Position ARC Cabin Velocity Cabin Velocity Error October 7, 2015 Enrique Busquets 12

13 Measurement Results Parameter Adaptation The parameter related to inertial load (θ 1 ) is crucial in achieving tracking Modifying the load inertia by changing the boom and arm positions is reflected on this parameter Pressure Tracking Pressure tracking with the H controller is greatly improved October 7, 2015 Enrique Busquets 13

14 Measurement Results ARC controller for cab speed control October 7, 2015 Enrique Busquets 14

15 Hydraulic Hybrid and DC Actuation E DC E e E cp E P EA ES Engine power can charge the Swing Engine drive power braking can be energy complemented can be stored with accumulator accumulator and actuate energy the swing drive October 7, 2015 Enrique Busquets 15

16 Hydraulic Hybrid Power Management Control Feedforward approach E DC E E 0 e min bsfc DC Primary unit charges accumulator Upper limit must be imposed on E A E e min bsfc E DC P A A EDC max Ee downsized max Uses available energy to charge accumulator S E SA 1 SA 0 EA min EA max Sets an upper limit on the amount of stored energy E e E cp E P EA ES E E 0 e min bsfc DC Accumulator is discharged to compliment engine Lower limit must be imposed on E A E e min bsfc E DC P A A Ee downsized max 1S E SA 1 SA 0 EA min EA max Uses stored energy to compliment engine Sets a lower limit on the amount of available stored energy October 7, 2015 Enrique Busquets 16

17 Engine Power Management Control Instantaneous optimization approach n min J min bsfc n, M k Q i J where e e e e Q DC err, c i1 bsfc n, M measured engine bsfc k Q performance gain 0 QDC, desired Q QDC err Q Q Q Q Jc penalizing factor Scalable engine map p, current DC, desired p, current DC, desired p, current Golden search For any given torque load, the minimum fuel consumption is at relatively low speeds min bsfc n, M e e October 7, 2015 Enrique Busquets 17

18 Power Management Simulation Results Maximum simulated engine power is 55% Aggressive truck-loading cycle from CAT measurements 55% Downsized engine max power is 20 kw October 7, 2015 Enrique Busquets 18

19 Power Management Measurement Results Maximum allowable engine power is 55% Measurements were performed with full-sized engine Engine operation is maintained below maximum allowed power October 7, 2015 Enrique Busquets 19

20 DC Actuation with Pump Switching on/off valves Fewer pumps than actuators Cost-effective solution to multi-actuator systems Lower parasitic losses Combined pumps flows Challenges were identified and control strategies were developed for a multiactuator test rig US Patent 8,191,290 B2 issued June 5, 2012 Actuator and supervisory-level controllers are necessary 1) Zimmerman, Josh Toward Optimal Multi-Actuator Displacement Controlled Mobile Hydraulic Systems. PhD thesis, Purdue University October 7, 2015 Enrique Busquets 20

21 DC Actuation with Pump Switching DRIVING AND ANY FLOW DIGGING DRIVING SUMMING COMBINATION October 7, 2015 Enrique Busquets 21

22 Actuator-Level Measurement Results Without Control Unit Displacement With Control Unit Displacement Actuator Position Actuator Position Pressures Pressures 1) Busquets, E. and Ivantysynova, M A Multi-Actuator Displacement-Controlled System with Pump Switching - A Study of the Architecture and Actuator-Level Control. Transactions of the Japanese Fluid Power System Society, Vol. 8, No. 1. October 7, 2015 Enrique Busquets 22

23 Pump Switching Measurement Results Without Control Pressure and motion transients are observed (evident by noise) With Control No pressure or motion transients are observed October 7, 2015 Enrique Busquets 23

24 Pump Switching Priority-Based Supervisory Focus on the proposed architecture Compare the proposed architecture with the stock excavator (LS system) Which actuator should operate??? Right track 2 Left track 3 Swing 4 Boom 5 Arm 6 Bucket 7 Blade 8 Offset Impossible w/dc Possible w/dc 1) Busquets, E. and Ivantysynova, M Priority-Based Supervisory Controller for a Displacement-Controlled Excavator with Pump Switching. ASME/BATH 2015 Symposium on Fluid Power & Motion Control. Chicago, IL, USA. October 7, 2015 Enrique Busquets 24

25 Supervisory Controller Measurements Trench-digging cycle - BUCKET October 7, 2015 Enrique Busquets 25

26 Supervisory Controller Measurements Trench-digging cycle - SWING October 7, 2015 Enrique Busquets 26

27 Conclusions Precision motion controls for secondary-controlled hydraulic hybrid drives under large and rapidlychanging inertial and dynamic loads were investigated, synthesized and implemented Effective and generalized power management schemes were developed and tested for both the hydraulic hybrid and the engine in the excavator prototype Actuator-level controls were developed for DC machines with pump switching leading to smooth switching transitions on the testbed Supervisory-level algorithms were researched and validated through measurements for DC machines with pump switching The above mentioned control strategies exploit the benefits of DC machines with hydraulic hybrids and pump switching while achieving conventional operability October 7, 2015 Enrique Busquets 27

28 Future Work Advanced control algorithms such as learning schemes that can exploit the hydraulic hybrid architecture can be formulated to further optimize fuel savings Actuator-level controls for pump switching can be improved by means of feedback making them robust against changes in the plant parameters Advanced supervisory controls can be developed for pump switching to supersede operator commands based on operating trends or desired performance October 7, 2015 Enrique Busquets 28

29 Thank you! Enrique Busquets Monika Ivantysynova October 7, 2015 Enrique Busquets 29