Have you ever heard of e-POWER technology? This is an innovative electrified propulsion system designed by the Japanese company Nissan which consists of a combustion engine that powers an electric motor. In this article we see how it works from a technical point of view, comparing it with other propulsion systems.
The different types of cars
Today there are three main categories of cars on the market:
- petrol (or diesel or LPG/methane) cars that power a combustion engine, also called “combustion engine”, connected directly to the wheels;
- electric cars, powered by an electric motor, directly connected to the wheels;
- hybrid cars, in which there is a combustion engine and an electric motor that together turn the wheels.
e-POWER works in an even different way. Let’s take the conceptual scheme of a full hybrid: in this case both the internal combustion engine and the electric one can technically drive the movement; in other words both motors are connected to the wheels. And in fact in a mild hybrid or full hybrid the start is often “electric” and then the combustion engine starts.
This is the diagram of an e-POWER engine. In this case the traction is 100% electric; in other words, the electric motor is the only one that acts directly on the wheels. The task of the petrol engine, in fact, is to provide energy (via a device called an inverter) to the electric motor, which is responsible for moving the wheels. The car battery then receives all the energy it needs from the petrol engine, which takes care of recharging it. It is certainly new in the world of cars but it is not new in an absolute sense: an example are diesel trains, which are still widely used, where the combustion engine acts as a generator to produce electricity, which is then used to power the electric motors that move the train. Similarly to these trains, the e-POWER heat engine is not directly connected to the wheels because its main purpose is to generate electricity.
How e-POWER technology works
The question to ask at this point is: how does the petrol engine understand when and how to intervene? Thanks to a control unit that optimizes exchanges based on certain parameters, such as the state of charge of the battery and driving conditions, with the aim of maximizing the time in which the combustion engine remains off.
Let’s take a couple of examples:
- if I am traveling at low speed the energy produced by the combustion engine goes partly to the electric motor and partly to the battery, recharging it. When the latter is fully charged, the combustion engine turns off and the car proceeds moved exclusively by the electrical energy contained in the battery.
- In case of strong acceleration or if I am traveling at high speed, however, the energy needed by the electric motor comes from both the combustion engine and the battery.
Another feature of e-POWER is the possibility for the driver to use the accelerator pedal like an “e-pedal” of an electric car: you press it and it accelerates; if instead you release the accelerator pedal, it slows down very decisively, up to a speed of around 10 km/h, and this serves to transform the kinetic energy of the car into electrical energy which recharges the battery. The concept is that of regenerative braking.
The benefits of e-POWER
An e-POWER car falls into the hybrid category and consequently enjoys all the related benefits: for example, in some cities it can be parked for free on the blue lines, the paid ones.
The consumption of e-POWER
Once we understand how it works, let’s also see how much a car with e-POWER technology consumes. To do this we take the data made available by Nissan for the Qashqai model, which exists in both e-POWER and mild hybrid versions.
in the city, according to Nissan (data which must obviously be verified on the road), we are at 5.1 liters per 100 km with e-POWER versus 8 liters per 100 km for the equivalent mild hybrid engine. In an extra-urban context with e-POWER 4.4 liters are consumed per 100 km compared to 6.2 liters per 100 km for the mild hybrid. On the motorway, however, 100 km are covered with 6.4 liters of petrol compared to the 6.8 liters needed to travel the same distance with the mild hybrid.
The average between the 3 main driving contexts (urban, extra-urban and on the motorway) is 5.3 liters of petrol per 100 km for the e-POWER, compared to 6.4 liters per 100 km for the mild hybrid.
