The weight of the Energica MotoE prototype has always been its Achilles heel and this is the aspect that was immediately identified as the one for Dorna and Energica to work on. Introducing technical innovations into a new category is not easy, even more so if a pandemic is in the middle. This is how the new MotoE engine, already ready to be mounted on the Ego Corsa last year, had to wait a year for the first laps. At the beginning of March, Energica put some important innovations to the test in MotoE tests in Jerez to reduce the weight of the motorcycle by 15 kg: the main ones are the new motor and the inverter.
The first characteristic of this engine is its weight, 10kg less than the previous model. A little weight has also been saved by the new inverter, bringing the MotoE 2022 prototypes to 247 kg, or around 15 kg less than the previous model.
The advantages of the new engine are not only measured in lower weight but also in a different mass distribution, less inertia and better handling, giving a completely new driving sensation to the motorcycle.
All these improvements are the result of an entirely new engine design. The MotoE motor of the previous three seasons was of the Permanent Magnet Synchronous Motor (PMSM) type. In this type of motor, the flow of alternating current through the stator windings generates a magnetic field that drives the permanent magnets mounted on the rotor shaft. The latter transmits the movement to the pinion and from there to the rear wheel.
The new 2022 motor, for its part, is of the synchronous reluctance type (SynRM – Synchronous Reluctance Motor) and is based on a completely different operating principle. The SynRM type motor operates on a long-known principle, but only with the recent development of sophisticated control systems has it been possible to take full advantage of this extremely efficient electrical technology.
In a SynRM motor, the rotor is designed to produce the lowest possible magnetic reluctance (the resistance to the flow of a magnetic field) in one direction and the highest possible reluctance in the perpendicular direction. The control system directs the stator's magnetic field, so that it "spins" around the rotor, generating torque that turns the rotor at the same frequency as the stator's magnetic field.
The average torque of the SynRM motor is due to the rotor anisotropy achieved by means of a large number of flow barriers (air gaps). Small permanent magnets are inserted into the flux barriers for an increase in prime torque density and power factor.
Devoid of the permanent magnets of its predecessor, the new motor which equips the MotoE prototypes has less electrical losses and is more efficient, especially at high revs. Still for the same reason, the operating temperatures of the stator windings are lower as are those of the shaft bearings. All of this has a positive impact on the overall efficiency of the new Energica powertrain.
The old permanent magnet powertrain guaranteed a maximum efficiency of 95%, which, combined with that of the inverter (92%), brought the overall system efficiency to 87%. The new 2022 engine features a peak efficiency of 97% as well as a wider high-efficiency operating range. The efficiency of the new inverter is 97%, bringing the overall efficiency to 94%, which is 7% more than the previous propulsion system. The maximum power and torque of the new 2022 engine are the same, while the maximum rotational speed is higher, allowing MotoE to increase the top speed.
The front water radiator is used to cool the inverter, via a plate heat exchanger, and the motor stator. The rotor, in turn, is air-cooled: fans mounted at both ends of the motor shaft route the hot air inside the motor to the side covers and from here the heat is dissipated into the external environment.
Source: Energica
