Hybrid vehicle

Since 2007, a hybrid-modeling cluster has been set up by Sherpa Engineering, in order to study the dynamic behavior of hybrid powertrains, as part of research and innovations projects of vehicle manufacturers.
 

STUDIED SYSTEMS


Hybrid powertrain is a complex system composed by required functions for the vehicle propulsion and its auxiliary devices, provided by at least two different energy supplies.
 
 
 
In most of studied cases, hybrid powertrain is made of two energy supplies : the main one is irreversible and the minor one is reversible.

 

Different degrees of hybridization have been already studied :
 
 
Micro-hybrid : compared with conventional vehicle, a reversible alternator provides functions such as managing engine stop & start and low-voltage battery regulation
 
 
Mild-hybrid : complementing to conventional vehicle, a oversized electric machine and a low-energy battery provide, besides already existing micro-hybrid functions, a power boost and regenerative breaking
 
 
Full-hybrid : compared with mild-hybrid vehicle, a more powerful electric machine and battery provide, besides already existing mild-hybrid functions, a pure electric vehicle mode and charge/discharge battery management.
 
 
Fuel Cell range extender : vehicle is only propelled by an electric machine. The fuel cell system provides electricity that either flows to the electric machine or to a high-energy battery for storage.
 
 
 
TECHNICAL STUDIES
Within the framework of research projects, Sherpa Engineering contributed to develop modeling tool to evaluate fuel consumption, exhaust gas emissions, and performance capabilities of vehicles.
 
Description of some technical studies
 
Modelling :
  • Functional analysis : available functionalities of hybrid powertrain (all-electric motive power mode, regenerative braking, charge/discharge battery, …)
  • Vehicle model : represents the longitudinal dynamics behavior of the vehicle, including main subsystems (power generator, coupling and transmission device, accumulator system, …), its control and driver
Simulations :
  • Performance : automotive test drives (acceleration and elasticity tests, maximum speed, grade capability, …),
  • Consumption : standard and customer cycles,
  • Range : standard and customer cycles,
Power management strategy :
  • Start/Stop : shutdown and restart engine condition,
  • Energy management : by controlling power flows to achieve several goals under constraints (to improve subsystems efficiency and reduce fuel consumption for example),
  • Regenerative braking : mechanism involved in converting some of vehicle kinetic energy into battery,
Preliminary design :
  • Sizing components : specification help (electric machine power, battery energy, …) to reach vehicle requirements,
Synthesis :
  • Analysis : of the simulation results (energy distribution, operating points, …)