General Motors has successfully patented an axial flux motor with a special hydraulic system for generating field weakening. The field weakening functionality allows the electric motor to be operated at higher speeds. The field weakening is typically implemented through inverter software, though this approach inevitably results in some losses. The objective of the mechanical systems is to minimise the losses associated with field weakening and reduce power consumption.
Variable air gap
The system comprises a hydraulic circuit. An increase in pressure within the circuit will result in a reduction in the distance between the rotor and stator discs. This increases the torque but reduces the speed. Conversely, if the distance is increased, the torque decreases and the speed increases. This is therefore a system with a variable air gap between the rotor and stator.
Relevance for the mass market
As axial flux machines are known to have high manufacturing costs, the system is more suitable for high-performance applications. To become attractive for the mass market, these production costs must therefore be reduced through new manufacturing processes.
Figure source: https://cdn.motor1.com/images/mgl/vxZ8r6/s4/yasa-axialflussmotor.webp
Text source: https://insideevs.de/news/722192/general-motors-axialflussmotor-hydrauliksystem-feldschwachung/
