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HyHIL: New Test Platform for the Development of Hybrid Vehicles

The HyHIL virtual hybrid test platform is now up and running. (Earlier post.) Upon completion in 2010, the HyHIL platform is expected to significantly reduce the time required for the design and development stage of a new hybrid architecture.

Launched in 2008 by D2T in partnership with IFP, Renault, the Laboratoire de Génie électrique de Grenoble (G2ELAB) and LMS-Imagine, and supported by the Mov'eo competitiveness cluster and FUI Fund, HyHIL uses a suite of generic tools to reproduce and assess the complex architectures of hybrid vehicles.

The physical modeling of the components is done on the LMS Imagine.Lab AMESim simulation platform. Piloting of the powertrain test bench and model execution are based on the real-time functionalities of D2T’s MORPHEE 2 test bench supervisor.

Three hybrid architectures have already been validated on this platform:

  • Pure thermal mode, with simulation of an alternator-starter.

  • Stop & Start mode, with simulation of the engine’s frequent stop/start phases.

  • Hybrid mode, with simulation of electric propulsion, energy recovery during deceleration phases and battery recharging.

These architectures have been tested over several standard driving cycles (NEDC, FTP, Artemis, etc.) using an energy supervisor developed by IFP, which is generic enough not to require specific calibration.

The parameters of the components can be adjusted directly on the powertrain test bench (electric engine power, vehicle mass, etc.) so that the effects on CO2 emissions and drivability can be analyzed immediately.

Validation will now focus on a hybrid 4-wheel drive architecture, to evaluate the vehicle’s dynamic behavior more accurately. This will also make it possible to fine-tune the development of functions relating to energy recovery and braking (interaction with ABS, ESP, etc.).

In addition, some more relevant models of electrical components (electric powertrain, battery, etc.) will be gradually integrated. Finally, work will be carried out to enhance the generic nature of the energy supervisor.



There is the start/stop mode in mild hybrids, you are not getting any mileage when the engine is running at a stop light. However, if you are running an alternator, you can leave the engine running and produce power for the batteries. This gives you some energy for the fuel that you are using while idling at a stop light.

Combine that with electric turbo compounding making exhaust energy create electricity from an alternator to charge the batteries. Add waste heat recovery from a turbine and alternator to do the same and you can have one really efficient machine, even at stop lights.


There shouldn't be any need to leave the engine running at a stoplight to produce power for the batteries. If you've got a hybrid with brake energy recovery you will have already produced more energy than you need while stopping for the light.


I do not think that regenerative braking provides enough energy to get the vehicle back up to 45 mph. I have read that regenerative braking provides less than 5% fuel savings. With charging batteries at the light, you have more than enough stored energy to get the vehicle back up to speed.


Regenerative braking MAY provide less than 5% fuel savings [I don't know if that's true or not so I'll take your word] but the real point is it captures ~40% of the car's brake energy. That's more than enough to pull away from a stoplight. Getting back up to full speed will still take burning some more gas but it's got to be more efficient to put that gas to work directly [engine>gearbox>wheels] than to go through the extra steps of the hybrid system [engine>generator>battery>motor>gearbox>wheels].


The extra steps of the hybrid system need to balance with the improvements in efficiency from running a smaller engine at a higher efficiency.

Most companies seem to be trying to mix the ICE and electric hardware. It might turn out to be easier to use a small ICE with 5 speed manual gearbox driving the front wheels, and an electric motor driving the rear wheels from a battery pack. Not only should it be cheaper, quicker and easier to build into existing production lines, it would allow you to convert most of the front wheel drive cars on the road today.


Do you mean something like this-


"'s got to be more efficient to put that gas to work directly..."

The engine may be very inefficient starting out from a stop to 45 mph. The regenerative braking energy of 40% to stop from 45 mph to 0 mph was put back in to launching the car from a stop. How much energy that is remains to be determined.

Let's say the energy from the regenerative braking gets you from 0 mph to 5 mph. It is your contention that going from 5 mph to 45 mph is done more efficiently with the engine and drive train. It takes a lot of energy to get a 3000 pound car to go from 0 mph to 5 mph.

It is my contention that it is done more efficiently with an electric motor powered by the electric energy stored from a continuously running optimally efficient engine and alternator genset. I contend that the engine running at an optimally efficient speed with a highly efficient alternator could run while waiting 30 seconds at the light and produce more than enough energy to launch the vehicle from 0 mph to 45 mph with the electric motor. I am talking series hybrid and/or range extender.

We agree to disagree.


Actually, as you've just described it, I can see it working - so we'll just have to agree to agree.



In order for the ICE + alternator to work efficiently when the car is stopped, the size of alternator would need to be about 10 KW or larger for most ICEs currently used in passenger cars.
This can be concluded from BSFC diagrams for engines (try finding them on internet).
Simply they say that at low loads engines runs inefficiently. On top of that you'll have battery losses from double conversion.
The size of most alternators on non stop-start capable cars is below 2 kW. Those stop-start capable cars have usually 2.5, 3 , up to 4 kW belt driven alternators.

New Honda Insight has motor of 10 kW - it's already a mild hybrid, and it comes with a price.


When I say alternator, I am referring to the 10-30 kw jobs. It probably would not make it to use the Chevy BAS and just put it in neutral. I am also referring to the range extended variety of hybrids.

This is the way of the trend. To make a range extended or series hybrid that can run the engine right where it is most efficient. The Volt did a trade off to extend battery life. If batteries become cheaper and oil more expensive, you can go for MPG.

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