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Mercedes-Benz’ anticipatory energy management system for hybrids

17 April 2014

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The Intelligent HYBRID operating strategy manages the state of charge of the battery to exploit the potential for energy recuperation. Click to enlarge.

Mercedes-Benz has developed an intelligent energy management system for hybrid vehicles that assesses the road ahead and takes it into account. The objectives of the “Intelligent HYBRID” system are to maximize the benefit of recuperation energy and to provide driving pleasure through the boost effect of the electric motor. (Earlier post.)

The Intelligent HYBRID operating strategy, which Mercedes-Benz has employed in the S-Class since summer 2013 and now also uses in the new C-Class, ensures that the high-voltage battery is always charged only enough to take advantage of all opportunities for recuperation provided by the route and the terrain.

To achieve this, the system constantly monitors the topography ahead of the vehicle. This works not only when route guidance by the navigation system is active, but also when that system is not in use.

Many hybrid vehicles waste energy when driving downhill, Mercedes says, because frequently the high-voltage battery has too high a charge at the wrong time to be able to store the additional recuperation energy thereby generated.

With the Mercedes system, if the state of charge of the battery is too high, the electric motor automatically boosts the combustion engine to discharge the battery enough to be able to store fully the expected recuperation energy. At the same time, thanks to the boost from the electric motor, the vehicle uses less fuel and thus produces fewer emissions during this phase.

The system uses data from the COMAND Online navigation system to calculate the recuperation potential of the road ahead. For example, the data provides forward-looking information about the route profile and speed limits in a one-meter grid for up to seven kilometers (4.3 miles) in advance.

This information is processed by the Central Powertrain Controller (CPC), which then initiates the anticipatory measures. It not only lowers the battery charge in line with the situation before a downhill stretch by expanding the all-electric or boost periods, but also controls the potentially necessary recharging of the battery by the combustion engine with foresight in order to benefit from the most favorable battery state of charge.

Further adaptive control algorithms additionally take the current vehicle weight, the driving behavior (including vehicle speed and braking behavior) and the load of the ancillary consumers into account for predicting the recuperation potential.

Intelligent HYBRID also functions when route guidance is inactive. In this case the system calculates the probability of the driver making a turn dependent on the category of the road. For example, if the hybrid vehicle is travelling on a motorway, it assumes that the vehicle will probably continue on the motorway for the next seven kilometers.

Intelligent HYBRID keeps the driver informed about an upcoming elevated recuperation potential by highlighting the road ahead of the vehicle in green on the energy flow display.

How much fuel is being saved depends on the topography. This has been demonstrated by experience from many thousands of test kilometers. The more mountains there are, the higher the fuel savings will be; i.e., the effect will be more noticeable in the mountains than on plains.

In developing new hybrid models, Mercedes-Benz says it has benefited immensely from cooperating with its Formula 1 racing team, which also makes use of advanced hybrid engines to achieve fuel savings. This can result in synergistic effects both for series production vehicles as well as racing cars.

April 17, 2014 in Controls and controllers, Hybrids | Permalink | Comments (6) | TrackBack (0)

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Comments

A smart idea if it can be automatically activated at the right times and the battery can take all the extra recharge. Is Toyota listening in?

It is clever, but they don't quote any figures for power saved.
+ I wonder have they patented the idea, in which case Toyota would have to come cap in hand.

Maybe you need a larger high voltage battery if you live in a very hilly area.

On a side note, as a cyclist, it is very galling to have to scrub off a load of speed at the bottom of a hill if you cannot proceed.
[ + I have read that the "Copenhagen wheel" only recovers 10% of the energy - can anyone confirm that ?]

Hybrid fuel economy differentiates driver behavior far more than a simple ICE drivetrain. You see this with two different well-intentioned Prius drivers in a family, one getting mid-40's and the other well into the 50's (mpg). The difference is more pronounced in Volt drivers, some of whom drive the car like a Series Hybrid and others who really understand the nuances of an EREV. My family members could not understand, when driving to Chicago, why I would override the car's controls and start the engine as we approached the Interstate. Of course, when entering the city, the hour or two of of the urban crawl, traffic jams, and sprints at the amber/red were done on a full battery, where the electric propulsion works its magic.

If the car can understand your route/destination, topography, and traffic, it can do so much to optimize energy source usage. Right now the people most satisfied with their plug-in platforms are intensely interested in what makes their cars tick. Conversely, like the NYT reporter with the Tesla S, the disappointed customers typically are the least informed. I have met fellow Leaf drivers who don't even understand the car's basic displays while I have an Android device connected for telemetry of all kinds. They can't figure out how I'm in the 200km club and they've never gotten more than 70 miles. (Ironically, some of these people once drove cars with manual chokes and regularly replaced points, plugs and condenser on their own -- a far more inconvenient world.) Building cars that handle "tactical" operational efficiency is essential for growing customer satisfaction and acceptance.

If you live in Netherland (only flat road) then saving is around 0 :)

I live in a hilly terain and my Prius battery is rarely at the full charge because of too much regen.

@Harvey,
I vaguely recall that Toyota may have applied for a patent on a similar idea some years ago. Of course, the car must know you destination in order to know what to do, and the car must have a GPS navigation system built in, which is OK for Mercedes owners, but a rather expensive option for less-expensive HEV's. The driver can have many preset destinations pre-programmed and can be selected by voice command or by pushing a single button, like home, work, country club, supermarket, theater, school etc. or by pointing at a location in the touch-sensitive map display, so letting the car know the destination is an easy thing to do.

I sincerely hope no company is awarded a patent on something as simple and ubiquitous as this. If navigation data is already present in the vehicle, it should be fairly simple (everything is simple for the person who does not have to actually do it...) to implement.

This function is exactly where even a mild hybrid could do the most benefit - by actively using motor and regen function where it gives the most benefit. On my daily commute I pass a couple of places both ways where I have to climb a hill, and even if I ease off the gas and let the speed decrease, the car shifts down just before I reach the peak. Those shifts are associated with considerable losses, and I only wish I would have an intelligent - or manual - electrical boost function that would allow me to stay in the overdrive over the summit (of that rolling hill).

Perhaps this function has limited potential, but it is only software, and thus virtually free in terms of development - and cost to the consumer (after paying off dev. cost in premiums for the most expensive vehicles)

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