Fraunhofer IISB’s aircraft motor - 750 kW, 94 kg delivering 8 kW/kg with Hairpin windings.

750 kW, 94 kg delivering 8 kW/kg

Hairpin windings are redefining motor design.

Fraunhofer IISB’s aircraft motor proves it.

I was reading this Fraunhofer IISB's

Hybrid-electric regional aircraft motor.

It built something impressive.

The motor of 750 kW, 94 kg

Delivering 8 kW/kg

Typical EV motors: ~2–4 kW/kg

Speed reaches 21,000 rpm.

 Torque is 350 Nm.

 Cooling uses direct oil spray.

 Rated at 65°C coolant.

They used NO15 electrical steel.

 Thickness is just 0.15 mm.

 This reduces eddy current losses.

Hairpin windings improve current density.

 Also improve thermal conduction.

 Stator has four decoupled sections.

 Each section uses separate inverter.

Let’s unpack the engineering behind the Hairpin winding. 👇

Hairpin windings pack more copper into slots.

 This increases the current-carrying capability.

 Higher current density means higher torque output.

They also improve heat transfer paths.

 Flat conductors touch stator core better.

 So cooling becomes more effective.

The stator is split into four sections.

 Each section is electrically isolated.

 Each section has its own inverter.

This creates a distributed drive architecture.

 Failure in one section stays localized.

 Remaining sections keep operating normally.

This improves fault tolerance significantly ⚙️

 One failure does not stop system.

This improves system reliability and safety.

 Critical for aerospace and high-power EVs.

This is for hybrid aircraft propulsion ✈️

 Target is 30% lower CO₂ emissions 🌱

Higher power density means lighter aircraft.

 Lighter aircraft means longer range or payload.

Motor design is no longer just electromagnetic.

 It is now system-level engineering

I believe this architecture could influence

High-speed EV motors next... Who agrees?

Would distributed hairpin windings become

standard for high-speed EV motors above 20,000 rpm?

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Source: ChargedEVs