The Rotor is the heart of an electric motor, converting electrical energy into mechanical rotation. In Motor Wiz, the Rotor Parameters module allows users to configure rotor geometry, magnetic properties, lamination details, and flux optimization parameters, which directly influence torque generation, efficiency, thermal performance, and vibration characteristics. From a user perspective, this module provides a comprehensive interface to simulate how rotor design choices impact the overall motor behavior under various operating conditions.
The rotor interacts dynamically with the stator through magnetic fields, and its design affects torque density, power output, efficiency, and heat dissipation. Motor Wiz allows users to explore different rotor types (IPMSM, SPMSM, SynRM, SCIM) and customize lamination, magnet placement, and stacking factors, providing immediate feedback through simulation outputs like torque-speed curves, loss maps, and thermal profiles.
i. Packing Factor
Definition: The lamination stacking/packing factor (kf1) is the ratio of the actual iron material volume to the total volume occupied by the stacked lamination, including air gaps, insulation, and adhesives.
Mathematical Formula:
Stacking Factor (kf1)= (Volume of Iron) / (Total Volume of Stack)
Typical Values:
The stacking factor typically ranges between 0.90 to 0.97, depending on the material and manufacturing process.
Example: If kf1 = 0.95, it means 95% of the volume is occupied by iron, while the remaining 5% consists of air gaps and insulation.
Impact on Motor Performance:
Higher kf1 (e.g., 0.97):
Lower kf1 (e.g., 0.90):
ii. Hole Type
The rotor hole type refers to the shape and configuration of magnet slots/holes in the rotor core. Different hole types impact the motor's flux linkage, reluctance torque, and performance. Below are common rotor hole types:
Hole Name | Description |
Angular V-stepped | A rotor hole with a V-shaped, angular geometry including stepped regions. |
Stepped | A hole profile with stepped diameters or widths. |
V-Stepped | A V-shaped hole including step variations along its depth. |
V-Shaped | A pure V-shaped hole, typically for embedding V-shaped magnets. |
iii. Magnet Type
Magnets are integral components in electric machines such as motors and generators, where their shape and orientation greatly influence magnetic flux distribution, torque production, and efficiency. Different magnet geometries are selected based on design constraints, performance goals, and manufacturing feasibility. Below is a table describing some commonly used magnet types:
Magnet Name | Description |
Ring Magnet | A circular magnet with a hole in the center, often used in axial flux machines or as rotor magnets in certain brushless DC motors. |
Spoke Rectangular Magnet | Rectangular magnets placed like spokes pointing outward from the center of a rotor. This configuration enhances torque and reduces flux leakage. |
Rectangular Magnet | A simple block-shaped magnet, typically embedded in rotors or stators. These are easy to manufacture and provide a uniform magnetic field. |
Polar Magnet | A magnet shaped or oriented to produce distinct magnetic poles aligned with the rotor or stator's geometric poles. Common in surface-mounted motors. |
iv. 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. |
v. 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.