General Motors has filed a patent with the European Patent Office detailing a new electric motor design aimed specifically at performance EVs. By strategically arranging wire and bar conductors within the stator of alternating-current, permanent-magnet (ACPM) motors, GM claims it can boost both high-speed and low-speed efficiency. This is an important step forward for delivering more responsive, energy-efficient electric performance.
GM’s Clever Conductor Trick to Cut Energy Loss
Electric motors typically employ mixed arrangements of rod/bar and wire conductors to optimize the motor for its intended purpose. Ohmic resistance leads to winding losses (also referred to as copper losses) – the undesired dissipation, in the form of heat, of electrical energy, particularly prevalent at high motor speeds. GM arranges the conductors in a way to limit these losses.
It does this by housing multi-wire conductors in the innermost slot layer, closest to the air gap between the rotor and stator, for optimal high-speed performance, and the bar conductors further away for optimal low-speed efficiency. GM’s secret sauce is getting the ratio of wire-to-bar conductors just right, and ensuring the cross-sectional area of the bar conductors is at least four times bigger than that of the wire conductors. It then adds a control system to the motor for independent operation and optimization of the bar and wire conductors, giving the motor both brains and brawn.
Dual-Speed Gains with Real-World Benefits
GM claims its innovative conductor layout resolves the typical trade-offs between high-speed power and low-speed efficiency. By optimizing how current flows through the motor, the design delivers multiple performance and efficiency advantages:
- Improved high-speed performance
- Better low-speed efficiency
- Increased driving range
- Lower overall energy consumption
- Enhanced driving performance
- Advantageous applications in EV sports cars
Refined, Not Revolutionary (But Still a Big Deal)
GM’s patent may not reinvent the electric motor, but it introduces a smart refinement: a carefully optimized placement of wire and bar conductors, paired with a dedicated control system to manage them independently. This combination allows for improved low-speed efficiency and high-speed performance, without introducing trade-offs. While it’s an evolutionary step rather than a radical one, it could offer a meaningful performance edge in future high-performance EVs.
