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Optimizing Rare Earth Magnet Usage in E-Motor Design With Ansys

Electric motors (E-motors) account for a significant portion of global energy consumption, comprising 70% of the electricity used in the industrial sector. The Electric Vehicle (EV) market, projected to grow at a CAGR of 9.82% from 2024 to 2028, is further driving the demand for efficient motors. However, the low efficiency of conventional motors contributes to increasing energy demand, posing a significant challenge.

To address this issue, countries are increasingly adopting electronically commutated motors (EC motors) that are more efficient, easy to use, and require less maintenance. In India, government initiatives like the National Motor Replacement Program (NMRE), AMRUT, Make in India, and the Smart City Mission have accelerated the development of advanced E-motor technologies, fostering innovation and sustainability.

Figure 1 Single Transmon Design

Figure 2 Field Distribution Plots

Challenges in Motor Design

Most electronically commutated motors incorporate permanent magnets (PMs) in their design. While effective, PMs pose several challenges:
  • High costs: Permanent magnets are expensive, and their production facilities are limited to a few countries.
  • Limited resources: The availability of rare-earth materials is scarce.
  • Demagnetization risks: PMs are prone to demagnetization under certain conditions.
  • Limited lifespan: This further impacts reliability.
To overcome these drawbacks, engineers are optimizing PM usage or designing PM-free alternatives, such as synchronous reluctance motors, by refining flux barrier designs. Achieving these optimizations requires multiple iterations, which makes prototyping and testing economically unfeasible.

The Role of Simulation in E-Motor Design

Simulation tools play a pivotal role in addressing these challenges by reducing development time and prototyping costs while ensuring efficient motor design and optimization.

ANSYS is a market leader in Finite Element Method (FEM) simulations, offering tools like MotorCAD, Maxwell, Fluent, and Mechanical for multiphysics analysis in motor design.
  • MotorCAD: A template-based simulation tool that performs electromagnetic, thermal, and mechanical analysis of rotating machines at the design and validation stage.
  • EV Applications: For electric vehicles, MotorCAD enables motor performance validation by incorporating vehicle dynamics and drive cycles.
The combination of MotorCAD and optiSLang is a game-changer in motor optimization, as it allows engineers to meet design objectives efficiently. By defining variable parameters and constraints, simulation engineers can identify optimal configurations with minimal effort.

Fig. 1 : Variable Parameters considered for optimizing torque ripple

How optiSLang Enhances Motor Optimization

Using optiSLang in the ANSYS Workbench platform, engineers can optimize designs by performing a systematic parametric analysis. For example:
  • Minimizing Torque Ripple: Variable parameters such as skew angle, slot size, and magnet dimensions are optimized to reduce torque ripple. As shown in Fig. 2, skew angle variation impacts torque ripple by 62%, making it the most influential parameter.
  • Multiphysics Analysis: Objectives and constraints for optimization can be considered across electromagnetic, thermal, and structural domains. optiSLang seamlessly integrates these aspects, enabling comprehensive design optimization.
  • Accounting for Faults and Thermal Effects: The simulation also evaluates PM demagnetization under faulty conditions and temperature rise, ensuring reliability and safety.
Fig. 2 : Influence of rotor skew angle on torque ripple

Conclusion:

Optimizing permanent magnet materials and dimensions requires multiple iterations, which is impractical and costly with traditional prototyping methods. ANSYS simulation tools significantly contribute to the E-motor industry by offering reliable, economical, and efficient solutions for designing high-performance motors. By leveraging tools like MotorCAD and optiSLang, engineers can develop motors that meet performance parameters while reducing costs and development time, paving the way for sustainable and innovative technologies in the EV and industrial sectors.

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