Abstract
A city bus with hybrid drive system was studied for its performance. The driveline under consideration consists of two alternative energy sources—an internal combustion engine (ICE) and kinetic energy storage (KES)—a hydrostatic transmission (HST), a drive axle and corresponding gears. A generalized law for HST control is obtained that satisfies kinematic and torque requirements for the alternative energy sources and the different modes of operation of the bus. A test stand was developed for validation of the chosen control strategy and for the energy flow simulations through the HST. The estimated maximum energy recovery potential is around 20–25%.
Highlights
Efficient energy use is a problem of current interest
This study investigates a hybrid hydrostatic transmission (HST) driveline with kinetic energy storage or flywheels (KES) and constant pressure system (CPS) control, intended for a heavy vehicle with non-steady modes of operation
The following assumptions are made: (a) HST works at a constant high pressure, except for the conventional mode; (b) internal combustion engine (ICE) works at its optimum operation point M ICE = const and n ICE = const, which corresponds to the minimum specific fuel consumption; if ICE is not in use, it is switched off; (c) KES losses are modeled by KES efficiency as shown in [17]; (d) volumetric and mechanical efficiencies of the separate hydraulic units are functions of current displacement and speed hydraulic units
Summary
Efficient energy use is a problem of current interest. Operation of heavy-duty vehicles in non-steady moving modes, such as a city bus, for example, is connected to proven inefficient energy use. A comparative analysis of several types of energy storage devices, presented in [7], indicates that higher fuel economy can be achieved by KES on heavy duty modes of vehicle operation. This study investigates a hybrid HST driveline with KES and CPS control, intended for a heavy vehicle with non-steady modes of operation. Based on the equations of power flows and mathematical description of the components, a global solution for the HST ratio is obtained in Section 3 as a function of vehicle modes of operation and driver requests.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
