The Stator Slot & Lamination section is a critical part of the Motor Wiz module, allowing users to define the magnetic and mechanical structure of the stator. From a user perspective, this section bridges the electromagnetic design, thermal management, and winding configuration, providing a detailed view of how lamination choice, slot geometry, and packing factors affect efficiency, torque, and overall motor performance.
Motor Wiz enables users to experiment with different slot shapes, lamination materials, and packing factors, instantly visualizing their impact on flux density, copper fill, and motor losses. This creates a design sandbox where engineers can optimize motor performance while balancing manufacturing constraints and thermal limits.
i. Packing Factor (Stacking Factor)
The packing factor (also called stacking factor) in stator lamination is a measure of how much of the stator cross-section is actually filled with steel, versus how much is lost to insulation, coating, and air gaps between lamination.
ii. Slot Type
Slot Name | Description |
Angular Stepped | A slot shape featuring angular sides with stepped geometry along its depth. |
Conventional | A standard, rectangular-like open slot with straight parallel sides. |
Conventional (smoother) | A conventional slot with smoother, rounded corners or slightly curved walls. |
Tapered Type-1 | A slot with side walls inclined (tapered) toward the slot opening. |
Flangeless | A slot shape without top flanges or lips, providing a fully open mouth to simplify coil installation. |
T-shaped Type-1 | A slot with a narrow opening and wider body, forming a "T" shape. |
Conventional (circular) | A conventional slot profile featuring a circular contour at the base or along its length. |
T-shaped Type-2 | A slot with a narrow opening and wider body, forming a "T" shape. |
Tapered Type-2 | A slot with side walls inclined (tapered) toward the slot opening. |
Stepped | A slot with multiple step changes in width or depth along its profile. |
ii. Axial Cooling Duct
Cooling ducts are channels in the stator or rotor core that allow airflow or coolant flow to remove heat, improving thermal performance and efficiency. In Pyleecan, three common shapes are modeled: Circular, Polar, and Trapeze.
Circular Duct
Shape: Simple circular hole through the lamination stack.
Advantages: Easy to manufacture, smooth airflow, minimal stress concentration.
Disadvantages: Limited surface contact for heat transfer; may not maximize cooling efficiency in high-power density motors.
Applications: Medium-power motors where simplicity and reliability are prioritized.
Polar Duct
Shape: Radially oriented, often sector-shaped ducts aligned toward rotor center.
Advantages: Directs cooling flow toward hot regions (e.g., winding hotspots); better thermal control.
Disadvantages: More complex to design and manufacture; may affect flux path slightly.
Applications: High-speed or high-efficiency motors with localized thermal hotspots.
Trapeze Duct
Shape: Trapezoidal cross-section; wider at one end to enhance airflow distribution.
Advantages: Maximizes airflow through critical sections; balances mechanical strength with thermal performance.
Disadvantages: Slightly complex manufacturing; requires precise lamination cutting.
Applications: High-power density motors where cooling efficiency is critical without compromising mechanical integrity.
Selection Criteria:
Motor power density, thermal load, and size constraints.
Ease of manufacturing and impact on magnetic flux.