The most important characteristic of axial flux motors is that the electromagnetic flux is aligned parallel to the motor axis. In conventional electric motors, it runs at right angles to it. The central components of the axial flux motor are designed as flat disks: Here, the stator is enclosed on the left and right by two rotors in a sandwich-like structure. This design, also known as an H-arrangement, allows for ideal transfer of the magnetic flux from the stator's magnetic field to the rotors. In the new CLA 45 4MATIC+, the motor on the front axle is just nine centimeters wide. The two rear axle motors measure even less, only about eight centimeters.
The drive motors are integrated into a High Performance Electric Drive Unit (HP.EDU) for each axle. The HP.EDU on the rear axle houses two axial flux motors, each with a compact single-speed planetary gearbox, all integrated into a single housing. Both the motors and gearboxes are oil-cooled. The necessary pump control unit, including hydraulic pumps and suction filters, is also integrated into the HP.EDU in a space-saving manner. In addition, there are two water-cooled silicon carbide (SiC) inverters – one per HP-EDU. The specific properties of silicon carbide offer numerous advantages for demanding applications requiring high voltages, currents, and operating temperatures, as well as high thermal conductivity. The rear axial-flow motors deliver up to 500 kW (680 hp).
