Do You Know the Next Big Trend in New Energy Vehicle Motors? With the global demand for new energy vehicles growing continuously, hub motor technology, as a revolutionary innovation in the electric vehicle field, is gradually becoming the focus of industry attention.

What Is an In-Wheel Motor and How Is It Structured?
In-Wheel Electric Motor and Its Structure
An in-wheel motor is a system where the motor is installed inside or near the wheel, making the wheel itself the driving unit.
Its core structure includes components like the stator, rotor, capacitor ring, power electroins, brakes, housing, and bearings.

How Are Brushless In-Wheel Motor Stator Cores Manufactured?
Let me, a manufacturer with ten years of experience in motor core production, guide you.
Stator
The stator is formed by embedding three-phase or multi-phase windings, made from layers of enameled wire, into core slots composed of silicon steel sheets or other low-loss magnetic materials. It is driven by alternating current supplied by an inverter, switching current in a specific sequence to rotate the rotor.

Laminated Core
The stator core is part of the motor’s magnetic circuit, housing the stator windings. There are two main stator designs: complete lamination stacks and segmented lamination cores.

If you want to know why automotive motors use segmented stator cores, you can read our “Why Do New Energy Vehicles Use Segmented Motor Lamination Cores“.
Typically, motor stator lamination stacks are made by stamping and stacking 0.2mm–0.5mm thick silicon steel sheets with an insulating surface.
For small batches: Silicon steel sheets are cut using laser or wire-cutting methods, then stacked using adhesive or laser welding to form the core.

For large batches: Slinky stamping and compound stamping methods are used for hub motor stator cores, while progressive stamping is applied for hub segmented stator cores.

Every in-wheel stator core has uniformly distributed slots for embedding the stator windings.
Why Is the Stator Core Wound?
Stator Winding
The stator windings form the electrical circuit of the motor. When three-phase AC flows through them, a rotating magnetic field is generated.
In-wheel motors use concentrated windings, wrapping copper wires around each stator tooth. Windings can be single-layer or double-layer.

Beyond traditional round wire windings, General Motors introduced the latest flat-wire BEV motor in 2017 with the Chevrolet Bolt.
This motor doubled its rotational speed and improved power density compared to earlier versions. The addition of more conductors per slot mitigated AC resistance at high speeds, increasing the copper fill factor and thus boosting power density.
Rotor
The rotor in an in-wheel motor is the rotating part, often composed of permanent magnets made from rare-earth alloys like neodymium-iron-boron (NdFeB) or samarium-cobalt (SmCo). Typically, the magnets are surface-mounted.

How Are hub Motors Categorized?
Types of Hub Motor
In-wheel motor systems can be classified into two structural types based on the rotor design: inner rotor and outer rotor.
Outer rotor motors: Low-speed motors with maximum speeds of 1000–1500 rpm. These do not require gear reduction, and the wheel speed matches the motor speed.
Inner rotor motors: High-speed motors with fixed-ratio reducers, achieving motor speeds up to 10,000 rpm to enhance power density.

Why Are In-Wheel Motors Gaining Popularity?
Advantages
Segmented cores reduce costs and improve material utilization.
High space efficiency.
Improved transmission efficiency with an energy conversion rate of up to 90%.
Simplified vehicle structure due to fewer transmission components.
Compatibility with various new energy vehicle technologies.
What Challenges Do Electric Hub Motors Face?
Disadvantages
Despite their advantages, in-wheel motors face challenges in practical applications, such as cost issues, increased unsprung mass, higher dynamic performance requirements, cooling difficulties, and durability in complex road conditions. These factors contribute to their limited adoption in mass-market passenger vehicles.
What Does the Future Hold for In-Wheel Motors?
As electric vehicle technology advances and market penetration increases, in-wheel motors are gaining traction in pure electric car, hybrid vehicles and electric bike. Their compact structure, high efficiency, and flexible drive capabilities make them ideal for small electric vehicles, low-speed EVs, and commercial vehicles in specific scenarios.
As a key technology for enhancing energy utilization efficiency, in-wheel motors are poised for significant growth under the dual drivers of policy support and market demand.
Hub Motor Stator Cores – Choose Lamnow

Lamnow, a leading motor core manufacturer in China, offers in-wheel stator core production using spiral and composite stamping for large batches and laser cutting with adhesive bonding for small batches. If you need in-wheel motor cores, feel free to contact us!