Fuel economy analysis and powertrain dynamic control of a parallel hydraulic hybrid vehicle

Zhou, Shilei

Fuel economy analysis and powertrain dynamic control of a parallel hydraulic hybrid vehicle

Zhou, Shilei

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Publication Type:: Thesis
Issue Date:: 2021

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Field	Value	Language
dc.contributor.author	Zhou, Shilei
dc.date.accessioned	2022-01-18T23:37:00Z
dc.date.available	2022-01-18T23:37:00Z
dc.date.issued	2021
dc.identifier.uri	http://hdl.handle.net/10453/153301
dc.description	University of Technology Sydney. Faculty of Engineering and Information Technology.	en_US.UTF-8
dc.description.abstract	This research investigates the fuel economy and powertrain vibration characteristics of a parallel hydraulic hybrid vehicle (PHHV). The main work includes: Hydraulic driving system parameter design, energy management strategy (EMS) design, powertrain vibration analysis and transient process control. Firstly, hydraulic driving system parameters are selected based on vehicle power analysis with the Chinese typical urban driving cycle (CTUDC) which is a typical urban driving cycle. PHHV powertrain dynamics are analyzed and components such as engine, hydraulic pump/motor (HPM) and accumulator are modelled to demonstrate the PHHV working principle. PHHV fuel economy is verified by both dynamic programming (DP) optimization and practical rule-based EMS. A lumped parameter dynamic model is built to capture the PHHV powertrain vibration characteristics including the natural frequencies and mode shapes. Then model reduction is conducted to simplify the model complexity while retaining the model fidelity in interested frequency range. The natural frequencies and mode shapes of PHHV powertrain are compared with the original vehicle powertrain which is the vehicle that PHHV refitted from. Results show that the vibration characteristics of PHHV powertrain are not significantly influenced by the addition of hydraulic driving system. Based on the powertrain dynamic model, control strategies are designed for transient process control such as mode switching and power on gear shifting. During mode switching, engine, HPM and engine clutch are coordinately controlled. LQR based closed-loop control strategy is adopted to analyze the effect of engine clutch engaging speed on vehicle jerk, clutch frictional work and hydraulic energy consumption. HPM torque is adjusted to compensate the engine clutch torque to maintain vehicle dynamic performance. To avoid vehicle driving torque interruption during gear shifting, power on gear shifting control strategy is designed. In the control strategy, HPM compensates engine torque when engine clutch is disengaged for gear shifting. Because the available HPM torque depends on its working pressure which varies a lot with different accumulator pressure state, the HPM torque compensation capability is investigated by analyzing the traction force requirement during gear shifting under typical urban driving cycles. With the motivation of taking the advantage of high power density of HPM for in-wheel drive, a novel in-wheel drive electric hydraulic hybrid vehicle (IHV) is proposed as a case study. Its energy economy and vertical vibration characteristics are researched and compared with the centralized motor drive electric vehicle (CEV) and in-wheel drive electric vehicle (IEV).	en_US.UTF-8
dc.format	Thesis (PhD)
dc.language.iso	en_US	en_US.UTF-8
dc.relation	https://opus.lib.uts.edu.au/bitstream/10453/153301/2/02whole.pdf
dc.rights	The author owns the copyright in this thesis including all reproduction and reuse rights for the work. The work may not be altered without the permission of the copyright owner. Attribution is essential when quoting or paraphrasing from this thesis.
dc.rights	au.edu.uts.lib/ppc
dc.rights	info:eu-repo/semantics/openAccess
dc.title	Fuel economy analysis and powertrain dynamic control of a parallel hydraulic hybrid vehicle	en_US.UTF-8
dc.type	Thesis
utslib.copyright.status	open_access	*

Abstract:

This research investigates the fuel economy and powertrain vibration characteristics of a parallel hydraulic hybrid vehicle (PHHV). The main work includes: Hydraulic driving system parameter design, energy management strategy (EMS) design, powertrain vibration analysis and transient process control. Firstly, hydraulic driving system parameters are selected based on vehicle power analysis with the Chinese typical urban driving cycle (CTUDC) which is a typical urban driving cycle. PHHV powertrain dynamics are analyzed and components such as engine, hydraulic pump/motor (HPM) and accumulator are modelled to demonstrate the PHHV working principle. PHHV fuel economy is verified by both dynamic programming (DP) optimization and practical rule-based EMS. A lumped parameter dynamic model is built to capture the PHHV powertrain vibration characteristics including the natural frequencies and mode shapes. Then model reduction is conducted to simplify the model complexity while retaining the model fidelity in interested frequency range. The natural frequencies and mode shapes of PHHV powertrain are compared with the original vehicle powertrain which is the vehicle that PHHV refitted from. Results show that the vibration characteristics of PHHV powertrain are not significantly influenced by the addition of hydraulic driving system. Based on the powertrain dynamic model, control strategies are designed for transient process control such as mode switching and power on gear shifting. During mode switching, engine, HPM and engine clutch are coordinately controlled. LQR based closed-loop control strategy is adopted to analyze the effect of engine clutch engaging speed on vehicle jerk, clutch frictional work and hydraulic energy consumption. HPM torque is adjusted to compensate the engine clutch torque to maintain vehicle dynamic performance. To avoid vehicle driving torque interruption during gear shifting, power on gear shifting control strategy is designed. In the control strategy, HPM compensates engine torque when engine clutch is disengaged for gear shifting. Because the available HPM torque depends on its working pressure which varies a lot with different accumulator pressure state, the HPM torque compensation capability is investigated by analyzing the traction force requirement during gear shifting under typical urban driving cycles. With the motivation of taking the advantage of high power density of HPM for in-wheel drive, a novel in-wheel drive electric hydraulic hybrid vehicle (IHV) is proposed as a case study. Its energy economy and vertical vibration characteristics are researched and compared with the centralized motor drive electric vehicle (CEV) and in-wheel drive electric vehicle (IEV).

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