Engine architecture

Operating principles

The ElectricMood engine is an axial flux permanent magnets brushless engine. The magnets are fixed on the wheel flanks so that the direction of the magnetic flux density is parallel to the rotation axis. The stator is made of conductors driving an electric current within the magnetic gap between magnets. This current combined with the intense magnetic field generates a torque between the rotor and the stator that allows the engine to transform the electric power that it receives into mechanical power.

The shape of the engine in this configuration is close to a disk and is suitable for the integration in a vehicle wheel. Moreover, this engine does not produce any resistant torque without current because the stator doesn't contain any ferromagnetic material. This way, it can be used as a free wheel with great efficiency.

Architecture of the ElectricMood engine

The rotor

The magnets fixed on both sides of the wheel are rare earth magnets of NdFeB kind. These magnets have a great energy density that allows the production of a very intense magnetic flux density. In addition, the magnetic field produced by these magnets is independent of the surrounding magnetic flux, so they can be considered as uniformly magnetized material. This very specific characteristic has been used to develop a computer code allowing to predict the magnetic field produced by a given magnet configuration. With this computer code we can optimize the configuration of the engine so as to maximize the torque produced by the engine. The configuration of the magnets used in the design doesn't need any ferromagnetic core to conduct the magnetic field lines, so the overall weight is again lowered.

Rotor

The stator

To produce the torque necessary to make the magnets turn and so the wheel, a stator made of electrically conductive material running an electrical current must be placed in the magnetic gap. ElectricMood has developed a technology allowing the usage of printed circuit boards on which copper traces are optimally arranged to minimize the Joule effect electrical losses. In addition to a great current density, this technology provides a great simplicity in the fabrication of the stator. Indeed, in the case of the ElectricMood engine, it is not necessary to wind up isolated copper strands by hand or with expensive machines around a ferromagnetic core.

The substrate used for standard printed circuit boards uses composite materials that give them excellent mechanical and thermal properties for a reduced weight. So, de facto, the ElectricMood engine stator is made from composite material.

This engine for which ElectricMood has a pending patent provides excellent performance and robustness for a reduced weight and size.

Printed circuit of the stator