Do you know the different “categories” of stator windings? Stator windings refer to copper wires wound around the stator core. Based on the shape and arrangement of the coils, they are divided into two types: concentrated winding vs distributed winding.
Simply put, concentrated windings wrap the coil around a single stator tooth, while distributed windings span at least two teeth.
So, when should you use concentrated windings? Let’s find out!
Concentrated Winding
In concentrated winding, each stator tooth carries one winding. This is primarily used for salient pole stators and is usually wound into rectangular-shaped coils.
Interestingly, concentrated windings generally have one coil per pole. However, some salient-pole types, such as shaded-pole motors, form two poles using a single coil.
How is concentrated winding wound?
Winding Methods
Automated Winding: This method uses flyer or needle winding machines to wrap copper wire around each stator tooth layer by layer.
Manual Winding: Workers manually wind copper wires into complete coils on fixtures and then fit them onto the stator teeth.
What are the advantages and disadvantages of concentrated winding?
Advantages
Lower manufacturing complexity due to single-tooth winding.
Minimal electromagnetic interference between coils.
Smaller axial height at the stator end reduces current losses.
Produces trapezoidal back EMF, enabling high torque at low speeds.
Disadvantages
Localized winding does not cover the entire stator core, resulting in uneven magnetic fields.
High harmonic losses at high speeds, particularly in the laminated windings and magnets.
The number of poles in concentrated windings is small, resulting in poor torque smoothness, which needs to be compensated by moving the relative position of the magnets on the rotor or changing the shape of the magnets.
Not suitable for high-power permanent magnet synchronous motors.
Applications
Concentrated windings are ideal for stator cores with small stack heights, such as small-diameter brushless motor stators, drone motor stators, and large-diameter hub motor cores. E-type transformer cores also use concentrated windings.
If you want to know about “brushless motor stator winding“, please read this article.
After understanding concentrated winding, are you curious about when to use distributed winding? Next, let’s talk about distributed winding.
Distributed Windings
As the name suggests, distributed windings spread coils across multiple stator teeth. These windings span at least two teeth, known as coil pitch or step size, which can be three, four, five, or more teeth.
Based on the arrangement, distributed windings are classified into concentric windings and lap windings.
Type Of Winding
What is concentric winding?
Concentric Windings
Formed by coils of similar shapes but different sizes, arranged concentrically around a common center.
Can be designed as two-plane or three-plane windings based on layout.
On which motors is concentric winding used?
Typically used in single phase motors and small-power three-phase asynchronous motors(induction motor) with large coil pitches.
What is a lap winding?
Lap Windings
Lap winding is generally composed of coils of the same shape and size, with one or two coil sides embedded in each slot, and evenly distributed one by one at the end of the slot.
How many types of lap winding are there?
The answer is 2, one is single-layer lap winding, and the other is double-layer lap winding.
Single-layer lap winding, or single-layered winding, is when only one coil side is embedded in each slot. When two coil sides belonging to different coil groups are embedded in each slot, they are placed in the upper and lower layers of the slot, which is double-layer lap winding, or double-layered winding.
According to the different changes in the embedded wiring method, stacked winding can be derived into cross-type, concentric cross-type, and single-double-layer mixed types.
Which motors use lap winding?
Generally, the stator winding of three-phase asynchronous motors with larger power mostly adopts double-layer stacking. Small motors mostly use derivative types of single-layer stacked windings, but rarely use single-layer stacked windings.
What are the advantages and disadvantages of distributed winding?
Advantages
Smooth sinusoidal back EMF, reducing harmonics and losses.
Higher efficiency, ideal for electric vehicles.
Minimal torque ripple and noise, perfect for precision machinery like machine tool spindles.
Large short-circuit torque with low starting torque.
Disadvantages
Larger winding heads increase complexity.
Higher manufacturing difficulty and process requirements.
Series winding sections have greater resistance, causing more losses.
Large winding copper loss, low efficiency.
What are the differences between stator concentrated winding and distributed winding?
Concentrated Winding VS Distributed Winding
| Concentrated Winding | Distributed Winding | |
| Pitch | 1 | At least 2 |
| End Winding Head Height | Low | High |
| Slot Fill Factor | Low | High |
| Cost | Low | High |
| Power Density | Low | High |
| Efficiency | Moderate | High |
When do you use concentrated and distributed windings? Now it is clear.
Concentrated windings are simpler and provide higher torque, but losses increase with speed. Distributed windings, though more complex to manufacture, deliver smoother operation, higher efficiency, and lower torque ripple, making them essential for precision and energy-efficient applications.
Stator Winding Solutions by Lamnow
Lamnow, a leading electric motor and generator core manufacturer in China, specializes in stator and rotor laminations, epoxy-coated stators, stator injection molding, stator windings, and rotor die-casting.
We offer integrated core and winding production, as well as standalone motor winding services. If you need electrical machine winding, contact Lamnow for reliable solutions!
