A Stator — What Is a Stator? | Reenives Drone Motor One-Stop Solution Supplier

What Is a Stator?

A stator is the stationary part of an electric motor or generator. The word comes from "stationary" — it stays fixed while the rotor rotates. In a brushless DC (BLDC) motor, the stator is the electromagnetic core that holds the copper windings and generates the rotating magnetic field that drives the rotor.

Physically, a stator is built from stacked thin silicon steel laminations — usually 0.15 mm to 0.50 mm thick — stamped into a ring shape with slots for the windings. Each lamination is coated with a thin insulation layer to limit eddy currents between layers, and the complete stack is secured by interlocking, bonding, welding, or clamping.

Key functions of a stator in a brushless motor:

• Holds the copper windings that carry motor current
• Generates the rotating magnetic field that drives the rotor
• Provides a low-reluctance magnetic path for the rotor's magnets
• Conducts heat from the windings to the motor housing
• Limits eddy current loss through thin, insulated laminations

Stator vs. rotor: The stator is stationary and holds the windings. The rotor is the rotating part carrying permanent magnets (in BLDC motors). Together they form the electromagnetic circuit that converts electrical energy into mechanical torque. In an outrunner motor — the dominant configuration in drones — the rotor is the outer bell that spins around the stator and mounts the propeller directly. In an inrunner motor, the rotor spins inside the stator.

Stator vs. housing: The stator is not the motor housing or the outer bell. It is the internal electromagnetic core. In an outrunner motor, the stator sits inside the rotating outer bell, surrounded by the rotor's magnets.

Put simply: a stator is the stationary magnetic heart of a motor or generator. Without a properly designed laminated stator, a brushless motor cannot generate efficient torque, and a generator cannot produce stable voltage.

A stator — precision laminated brushless motor stator core with copper windings, manufactured by Reenives with imported high-speed stamping & epoxy powder coating lines.

Types of Stators

Stators come in several configurations, each suited to different motor or generator architectures. Reenives manufactures the following types:

• Outrunner Motor Stators — The stator is fixed inside while the rotor (outer bell) spins around it. The dominant configuration in drone propulsion and UAV motors.
• Inrunner Motor Stators — The rotor spins inside the stator. Used in high-RPM ducted fan, EDF, and robotics applications.
• Segmented Stators — Individual teeth are wound separately and then assembled into a ring, achieving higher slot fill factors and better copper utilization.
• One-Piece Laminated Stators — Traditional stacked lamination construction with full-ring slots, cost-effective for medium to high-volume production.
• Bonded Stators — Laminations bonded with adhesive instead of interlocking, reducing eddy current losses and vibration — preferred for gimbal motors and low-NVH applications.
• Epoxy-Coated Stators — Powder-coated for enhanced insulation, corrosion resistance, and wire adhesion. H-Class 180°C electrostatic coating is standard for high-RPM drone stators.
• Generator / Alternator Stators — Stators optimized for voltage waveform quality, output stability, and continuous thermal performance rather than torque density.
• Gimbal Stators — Ultra-low cogging, high pole count stators for camera stabilization systems.
• Custom Stators — Private mould development for unique slot counts, diameters, stack lengths, and mounting interfaces.

Whether you need a standard 12-slot/14-pole drone motor stator or a custom high-frequency stator, Reenives can deliver.

Key Specifications & Data

Below are typical specifications for Reenives brushless motor stators. Custom values are available upon request.

Data source: Reenives internal testing & supplier material datasheets, 2024–2025. Actual values may vary by design.

Applications & Why the Stator Matters

The stator directly determines the motor's performance across every operating condition. Here is why stator design and quality matter so much:

• Core Loss & Efficiency — Thin, low-loss laminations reduce eddy current losses, directly improving motor efficiency and flight endurance in UAV applications.
• Thermal Performance — Lower core loss means less heat generation, keeping the motor cooler and extending winding and magnet life.
• Slot Fill Factor — Accurate stamping of slot geometry enables higher copper fill, increasing torque density and reducing I²R losses.
• Air Gap Consistency — Tight stator tolerances keep the air gap uniform, essential for smooth high-RPM operation and low vibration.
• Cogging Torque & Control Smoothness — Slot/pole combination and lamination edge quality determine cogging torque, which affects FPV control feel and gimbal smoothness.
• Production Consistency — Consistent stator geometry and stacking pressure ensure that every motor in a batch delivers the same KV, thrust, and thermal behavior.

Reenives stators are used across a wide range of UAV, robotics, and industrial applications:

• FPV Racing Drones — High RPM, lightweight stators with low cogging torque and fast throttle response.
• Cinematic & Photography Drones — Smooth, vibration-free stators for stable aerial footage.
• Agricultural Spraying Drones — Corrosion-resistant epoxy-coated stators for harsh chemical environments.
• Industrial Inspection Drones — High-torque stators for long endurance and heavy payloads.
• eVTOL & UAV Propulsion — Custom high-power stators for next-generation air mobility.
• UAV Onboard Generators — Generator stators for hybrid-electric power systems.
• Camera Gimbals & Robot Actuators — Ultra-low cogging stators for precise motion control.
• General BLDC Motors — Fans, pumps, power tools, and automotive actuators.

Reenives stators power FPV, agricultural, cinematic, and industrial UAVs — and a wide range of industrial BLDC motors worldwide.

How to Select the Right Stator

Choosing the correct stator for your motor or generator involves several engineering decisions. Follow these steps:

1. Determine the Application Type — Motor or generator? Outrunner or inrunner? Gimbal or propulsion? Each has different design priorities.
2. Determine Required Torque & RPM — Higher torque needs more stack length or larger diameter. High RPM demands thinner laminations and low-loss material.
3. Select Slot/Pole Combination — Common drone motors use 12S/14P or 9S/6P. Gimbal motors use higher pole counts for smoother motion. Generators may use distributed windings for cleaner waveforms.
4. Choose Lamination Thickness — For high-frequency operation (e.g., 400Hz+), use 0.15–0.20 mm laminations to reduce eddy current losses. For lower RPM, 0.35–0.50 mm is cost-effective.
5. Select Material Grade — Lower-loss silicon steel grades (e.g., 20JNEH1200) reduce heat but cost more. Balance performance and budget.
6. Consider Assembly Method — Segmented stators offer higher slot fill; bonded stators reduce vibration; interlocked stators are the most economical.
7. Specify Insulation & Coating — Epoxy powder coating with H-Class 180°C rating is recommended for moisture, vibration, and chemical resistance.
8. Request Samples & Test — Reenives provides free samples for qualified projects. Test core loss, cogging torque, temperature rise, and mechanical fit.

FAQ — Stator Parameters

Summary — A Stator Is the Electromagnetic Heart of Every Brushless Motor