What exactly is light hybridization?



It's the revolution in batteries! Since the switch to 12 volts in the 1950s, not much has happened on the storage and distribution of electricity for gasoline cars. But needs and realities are changing.

The switch to 48-volt (or light hybrid) systems meets two main needs: reducing polluting emissions and providing the power needed for ever-increasing modern equipment.

A little physics...


The electrical power transmitted (expressed in watts) is the product of voltage (expressed in volts) by intensity (expressed in amps). To transmit more power, you can increase the intensity of the current. Problem, you need larger wires (thus heavier), stronger electrical circuits (thus more expensive) and you increase the energy losses (proportionate to the square of intensity). So it's better to increase the tension. This is the case, for example, of Hydro-Québec's transmission systems, which use very high voltages to transmit large powers.

But then, you might say, why not increase the voltage in the cars to 100, 200 or 300 volts? That is where security issues come into play. An electric shock for humans is considered safe up to 60 volts. Beyond this voltage, we pass in the high voltage and the standards require that reinforced cables, special connectors and orange signals be installed in cars, resulting in excess costs. That's why firefighters use special precautions when working on damaged electric cars, including 300-volt circuits. That's why the value was set at 48 volts.

The 12 volts did not say its last word

As early as the mid-1990s, several companies, led by Daimler Benz, began working on a 42-volt system. It was expected to be widespread on standard cars in the mid-2000s. But given the development and implementation costs for the industry, nothing came to fruition.

But when it came to meeting new and ever-increasing pollution standards, the 48 volts came naturally back to the fore. While adding a twist: the 12-volt system is still present. Because some components work perfectly in 12 volts and this means you don't have to redevelop many parts (such as electric glass motors or infotainment systems).

For example, a conventional 48-volt system consists of three modules: 48 volts (battery, continuous alternative inverter, battery controller), 12 volts (battery, 48-12-volt continuous current converter) and engine support.
 
Light hybridization

The 12-volt module continues to power the components that require the least electrical power. It receives its energy from the 48-volt module via the converter. Its battery is smaller than traditional batteries. The 48-volt module interacts with engine support and powers the components that are the big power seekers.

The engine assistance consists of an engine/generator with alternating current (hence the need for the inverter, which transforms the direct current into an alternating current) which replaces the starter and alternator and can also provide additional power to the rolling train (engine function). And as in a conventional hybrid car, it can recover the mechanical energy of braking and turn it into electric energy (generator function). Because it is subject to heavy loads, this engine uses liquid cooling.

This results in a lightweight hybridization that offers 50-70% of the gains of a conventional hybrid system at only 30% of the cost. In addition, the "Start/stop" function is more efficient and offers more frank start-ups.

This module can also include a compressor (supercharger) that is now driven by an electric motor instead of a belt connected to the vilebrequin. The advantage of this technology is to offer a faster response (you no longer have to wait for the thermal engine to go up in the towers to increase the air pressure) and therefore better optimized according to traffic conditions.

But that's not all!

Other new technologies may benefit from excess electrical power. For example, Bentley unveiled a system of active anti-roll bars on the Bentayga to improve the handling of its SUV.

Then there is the possibility of decoupling certain engine accessories, such as the water pump or air conditioner, which are normally driven by belt. By combining them with an electric motor, they can be operated according to real needs and no longer according to the engine speed, thus reducing losses.

For example, it is winter and you live at the bottom of a coast. To climb it, you have to turn the engine up in revolution, so the water pump runs faster, which sends more cooling liquid into the engine, thus delaying its temperature. In this situation, with electrical assistance, the pump would run at low speed, even if the engine was running at 4,000 rpm, until the temperature was put in.

Finally, some are considering electric heating catalysts, speeding up temperature, thus reducing cold pollutant emissions. As can be seen, thanks to the 48 volts, the thermal engine still has a few laps up its sleeve to face the challenges of modern mobility.

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