Modelling and analysis of hydraulic step-down switching converters
Keywords:digital hydraulics, hydraulic switching converter, hydraulic valve, PWM switched valve
In this study, a steady state analysis of step-down converter systems, considering the load losses in the inertance tube and switched valve, is presented. The model describes the behaviour of the average load pressure as a function of the pulse-width modulated duty cycle. The steady state expressions for the load flow rate, high and low supply flow rates, and system efficiency are also discussed. A system prototype was developed and tested to evaluate the model accuracy. The system parameters (e.g. tube diameter and length and switching frequency) were analysed to predict the best system configuration. The study describes how the system efficiency is influenced by these parameters. The model presented allows the ideal parameter combination for maximum efficiency to be determined. It can be used for the preliminary design of switching converters, and a further time or frequency analysis can be performed for system optimization.
Brown, F.T., 1987. Switched reactance hydraulics: a new way
to control fluid power. Proceedings of the national conference
on fluid power. Chicago: National Fluid Power
Brown, F.T., Tentarelli, S.C., and Ramachandran, S.A., 1988. A
hydraulic rotary switched-inertance servo-transformer.
Transactions of ASME: journal of dynamic systems, measurement,
and control, 110, 144–150.
De Negri, V.J., Wang, P., Plummer, A., Johnston, D.N., 2014.
Behavioural prediction of hydraulic step-up switching converters.
International journal of fluid power, 15 (1), 1–9.
Eggers, B., Rahmfeld, R., and Ivantysynova, M., 2005. An
energetic comparison between valveless and valve
controlled active vibration damping for off-road vehicles.
Proceedings of the 6th JFPS international symposium on
fluid power. Tsukuba: Japan Fluid Power System Society.
Fox, R.W., McDonald, A.T., and Pritchard, P.J., 2011. Introduction
to fluid mechanics, 8th ed. Hoboken, NJ: Wiley.
Heitzig, S. and Theissen, H., 2011. Aspects of digital pumps in
closed circuit. The forth workshop on digital fluid power,
–22 September 2011. Linz: ACCM, 39–50.
Heitzig, S., Sgro, S., and Theissen, H., 2012. Energy efficiency
of hydraulic systems with shared digital pumps.
International journal of fluid power, 13, 49–57.
Hettrich, H., Bauer, F., and Fuchshumer, F., 2009. Speed
controlled, energy efficient fan drive within a constant pressure
system. Proceedings of the second workshop on digital
fluid power. Linz: ACCM, 62–71.
Johnston, D.N., 2009. A switched inertance device for efficient
control of pressure and flow. Proceedings of the ASME
dynamic systems and control conference –
DSCC2009. Hollywood: ASME.
Karvonen, M., Heikkilä, M., Huova, M. and Linjama,
M., 2014. Analysis by simulation of different control algorithms
of a digital hydraulic two-actuator system. International
journal of fluid power, 15 (1), 33–44.
Kogler, H. and Manhartsgruber, B., 2009. Simulation tools and
control design for fast switching hydraulic systems.
Proceedings of the second workshop on digital fluid power.
Linz: Tampere University of Technology, 85–93.
Kogler, H. and Scheidl, R., 2008. Two basic concepts of hydraulic
switching converters. Proceedings of the first workshop
on digital fluid power. Tampere: ACCM, 113–128.
Linjama, M., 2011. Digital fluid power-state of the art. The
twelfth Scandinavian international conference on fluid
power, Tampere: Tampere University of Technology.
Linjama, M. and Vilenius, M., 2008. Digital hydraulics –
towards perfect valve technology. Technology. Digitalna
Hidravlika, 14 (2), 138–148.
Manhartsgruber, B., Mikota, G., and Scheidl, R., 2005. Modelling
of a switching control hydraulic system. Mathematical
and computer modelling of dynamical systems, 11 (3),
Millmann, J. and Taub, H., 1965. Pulse, digital, and switching
waveforms. New York: McGraw-Hill.
Murrenhoff, H. 2003. Trends in valve development. O+P –
Ölhydraulik und Pneumatik, 46 (4), 1–36.
Rampen, W. 2006. Gearless transmissions for large wind turbines–
the history and future of hydraulic drives. Proceedings
of the 8th German Wind Energy Conference (DEWEK
. Bremen: Deutsches Windenergie-Institut.
Scheidl, R., Manhartsgruber, B., and Winkler, B., 2008.
Hydraulic switching control – principles and state of the
art. Proceedings of the first workshop on digital fluid
power. Tampere, 31–49.
Scheidl, R., Linjama, M., and Schmidt, S., 2011. Is the future
of fluid power digital? Proceedings of the institution of
mechanical engineers. Part I: journal of systems and control
engineering, 226 (6), 721–723.
Uusitalo, J.-P., et al., 2010. Novel bistable hammer valve for
digital hydraulics. International journal of fluid power, 11
Wang, P., et al., 2011a. The influence of wave effects on digital
switching valve performance. Proceedings of the fourth
workshop on digital fluid power. Linz: ACCM, 10–25.
Wang, F., Gu, L., and Chen, Y., 2011b. A continuously variable
hydraulic pressure converter based on high-speed on–off
valves. Mechatronics, 21, 1298–1308.
Willkomm, J., Wahler, M., and Weber, J., 2014. Processadapted
control to maximize dynamics of displacementvariable
pumps. Symposium on fluid power & motion
control. Bath: University of Bath, 10–12.
Winkler, B., Plöckinger, A., and Scheidl, R., 2008. Components
for digital and switching hydraulics. Proceedings of
the first workshop on digital fluid power. Tampere: Tampere
University of Technology, 53–76.
Winkler, B., Ploeckinger, A., and Scheidl, R., 2010. A novel
piloted fast switching multi poppet valve. International
journal of fluid power, 11, 7–14.