Abstract:

This video details an innovative dual-rotor, radial flux electric motor developed by the Munich-based startup Deep Drive. The core innovation is a yokeless stator design, made possible by patented, torsion-resistant copper windings. These windings, constructed from copper bars in a truss-like structure, provide the necessary structural rigidity to withstand magnetic forces and simultaneously act as the primary thermal pathway, conducting heat directly to the motor's cooled housing. By eliminating the heavy, passive stator yoke, the design achieves significant improvements in torque density, efficiency (especially at low loads), and material usage. The motor reportedly uses 80% less iron and 50% less magnetic material, leading to a 30% reduction in cost per newton-meter of torque.

Deep Drive's Revolutionary Yokeless EV Motor

• 0:00 Innovative Motor Design: Deep Drive has developed a dual-rotor, radial flux electric motor, a departure from the traditional single-rotor design common in EVs.
• 1:21 Dual-Rotor "Sandwich": The motor features an inner and an outer rotor that spin together, with the stator placed between them. This configuration doubles the active surface area between the rotors and stator, which is key for generating high torque.
• 2:19 Eliminating the Yoke: The design removes the traditional stator yoke—a heavy iron component that provides structural support, completes the magnetic circuit, and helps with cooling. In a dual-rotor design, the magnetic field connects directly between the two rotors, making the yoke's magnetic function redundant.
• 5:05 Core Innovation: Torsion-Resistant Windings: The functions of the removed yoke (structural support and cooling) are replaced by the windings themselves. They are made from solid copper bars arranged in a rigid, self-supporting truss-like structure that resists twisting forces and is attached directly to the motor housing.
• 9:05 Integrated Cooling Path: These thick copper windings also provide an excellent thermal path, conducting heat directly away from its source to the coolant-filled motor housing. This solves both the structural and thermal challenges of a yokeless design.
• 11:01 High Performance: The in-wheel version of the motor weighs only 34 kg yet produces over 2,000 Nm of torque and a peak power of 180 kW. The design is claimed to be up to 20% more efficient over a real-world driving cycle.
• 11:42 Significant Material and Cost Savings: By removing the yoke and using magnets more effectively, the motor requires approximately 80% less iron and 50% less magnetic material. This results in a claimed 30% lower cost per newton-meter of torque.
• 12:36 Commercialization Path: Deep Drive has active partnerships with BMW and other automakers, with plans to begin small-scale production by 2026 and large-scale production by 2028.