H3X HPDM-3000 Megawatt-Class Motor — A Key Enabler for Large Electric Aircraft

H3X Technologies
3 min readJul 1, 2022

United States, June 30, 2022H3X is excited to introduce the next product in their roadmap, the HPDM-3000. This is a 2.8MW ultra-high power density integrated modular motor drive (IMMD) intended for primary propulsor applications on large electric aircraft. It is based on the same core technology that is being proven out in their HPDM-250 and, as such, maintains its 12 kW/kg power density. Additionally, there are a number of system-level benefits realized as the technology scales to the megawatt-class including: the ability to directly drive the propeller without a gearbox, inherent fault tolerance and redundancy from twelve independent drive sectors, total and unsurpassed integration of the inverters and motor, and an extraordinarily compact package in a class of its own, weighing in at approximately 220 kilograms.

“We see this becoming the gold standard for regional and narrow-body electric aircraft propulsion. There is nothing out there that compares in terms of power density, fault tolerance, and modularity,” said Jason Sylvestre, Co-Founder and CEO of H3X. “The electric regional and narrow body jet market is still in its infancy. Airframers need high power density aviation-grade systems in the MW-class to electrify their aircraft and those currently don’t exist. This Electric Propulsion Unit (EPU) will serve a critical unmet need in the supply chain and trigger an acceleration of progress towards widespread, carbon-free, sustainable aviation.”

Certifiability, safety, reliability, and performance were the primary drivers H3X considered when architecting the HPDM-3000. There is no single point of electrical failure, so if a non-recoverable fault occurs in a single sector, the unit can continue operating safely at >90% power continuously. Additionally, the unique architecture of this EPU enables redundancy chains that can extend into the energy storage system, where multiple independent series strings of fuel cells or batteries could be used to drive each of the independent inverter sectors.

The HPDM-3000 is axially stackable up to six times, facilitating the formation of up to 17MW propulsors for even larger aircraft. This modular “building block” approach is critical for reducing both development effort, certification time, and cost. As you increase the number of HPDM-3000s, the fault tolerance increases proportionally. Two units stacked would have 24 independent systems, three units stacked would have 36 independent systems, and so on.

The HPDM-3000 will be a key enabler for large electric aircraft manufacturers, as it is designed to replace existing turbomachinery and be compatible with existing propeller systems. There is no single innovation that gets the HPDM to these high power density levels, but is rather the culmination of advancements in several different areas including:

  • Novel thermally conductive, partial discharge-resistant high voltage insulation system
  • High copper fill factor, low AC loss winding technology
  • Liquid-cooled cold plates that simultaneously reject heat from the motor and inverters
  • High frequency Silicon Carbide power electronics with ultra-low DC link inductance and lightweight, high attenuation EMI filtering
  • Advanced fault-tolerant, multi-sector, field-oriented control with no controller-to-controller communication.
  • Unsurpassed integration and co-optimization

A high-level overview of the system is shown in the table below.

The HPDM-3000 is the result of H3X innovation in electric machines, power electronics, material science, control systems, and advanced manufacturing. They are targeting to have prototypes available for iron bird testing in Q1 2024. H3X is seeking customers to partner with to develop and certify this unit for large electric aircraft. A white paper is available for interested customers.

Connect with H3X on LinkedIn.



H3X Technologies

The startup building the next generation of electric aircraft propulsion systems.