Renault eMotors : High efficiency without rare earths!

When it comes to electric motors, Renault Group boasts a wealth of expertise built up over many years. We could, of course, go back to the first electric models launched several decades ago but it was in 2012 that Renault Group invested massively in this sector, notably with the launch of the Renault ZOE, which covered more than 15 million kilometers.

And right from the launch of the Renault ZOE in 2012, the Group entered this market with a highly innovative engine technology: the EESM.

What is EESM ?

An electric motor generates torque through the interaction of 2 magnetic fields, one from the stator, the other from the rotor. In a conventional electric motor, the rotor magnetic field is created by permanent magnets. The EESM or wound-rotor synchronous motor differs in that no magnets are used to create the rotor's magnetic field. Instead, a winding of copper wires creates the field in the same way as an electromagnet. It is therefore necessary to supply electrical power to the rotor, as it is not "natively" polarized.

This power supply is provided by brushes that create contact between the high-voltage supply and the rotor.

Note that when the rotor is not supplied with electric current, there is no magnetic field present, unlike in a permanent magnet motor.

In 2021, the EESM vs PMSM comparative study concluded that the EESM gives a 2% gain in fuel consumption, i.e. about 15 km out of 650 KM for a C-segment SUV. 

To achieve this level of performance, the technology has been the subject of no fewer than 124 patents. That shows Renault Group's commitment and investment in this area!

The 3rd generation for Renault 5 E-Tech electric

New Renault 5 E-Tech electric launched this year is equipped with our 3rd generation electric motor based on this technology. This 6AK motor is derived from the one used in the Megane E-Tech Electric. Combined with a 52kWh battery, this motor delivers maximum power of 110kW and torque of 245Nm, with acceleration from 0 to 100km/h in less than 9 seconds. It is manufactured at the Cléon plant and comes in 3 power levels: 70kW, 90kW and 110kW.

This new GMPE is combined with an 11kW on-board charger offering new reversible charging functions, also known as V2G for Vehicle to Grid. The Renault 5 thus becomes a reservoir of energy that can be used by the home or the grid at times of peak demand.

A fourth generation soon on the street

And soon, the arrival of an even more powerful fourth generation.

Renault Group's expertise has enabled us to supply an "all-in-one" architecture for this new E7A, our 4th generation electric motor, combining the electric machine, an innovative reducer (the gearbox of an electric vehicle) and the inverter in a single unit. The benefits are both economic and technical (reduced friction losses).  And let's not forget that this "all-in-one" architecture has another major advantage: it is 30% more compact than the current motors equipping the Megane E-Tech electric and Scenic E-Tech electric, at equivalent power.

With regard to the stator, another key element of the motor, its Hairpin technology for assembling copper wires increases copper density while ensuring very good insulation of the wires between each other, enabling the switch to 800-volt batteries without risk of short-circuit. And a system voltage of 800 volts means, among other things, faster battery recharging times.

The best-in-class efficiency of this new motor will be further optimized by a state-of-the-art assembly technique allowing a maximum clearance of 0.6mm between rotor and stator - a very small gap for a rotor rotating at up to 15,000 rpm inside the stator. Maintaining this gap is key to optimum motor performance and efficiency.

Our E7A will thus be able to develop more than 200 kW. A concentration of innovations for a more powerful, more compact and cleaner motor.

By favoring wound rotors over permanent magnet technologies for its electric motors, Renault Group not only secures its supply, but also maintains its independence from countries producing rare earths and magnets. And the absence of rare earths reduces its carbon footprint by 30%.

At this stage, this engine is still in the development phase. Large-scale production is scheduled for 2027 at our Cléon plant in France.

Other automakers are also interested in this technology, which offers many advantages. BMW Group , for example, adopted it for its fifth-generation eDrive powertrains

And on our side, we are already working for our subsequent generations on brushless rotor control for even greater efficiency.

The best is yet to come. Stay tuned for further information on the E7A efficiency and our other daring choices, already full of promises, such as the axial-flow motor we are currently developing with WHYLOT .