Case Study: Using Simulation to Optimize Motor Design for Commercial-Grade Lawnmowers

Company Background

ETA Green Power is a UK-based leader in power electronics and magnetics, specializing in electrification solutions for OEMs and Tier 1 suppliers in e-Mobility, Outdoor Power Equipment, and compact construction industries. Leveraging a portfolio of over 20 patents across 40+ countries, ETA delivers patented technologies that provide up to 60% performance improvements while reducing costs, empowering its partners with a decisive competitive edge.

Through a unique licensing model, ETA enables customers to access cutting-edge innovations while maintaining full control of their product development and supply chains. Its integrated approach ensures optimal system efficiency and mitigates single points of failure, delivering reliable and robust solutions. With a strong commitment to collaboration, ETA offers ongoing support and knowledge transfer, driving successful implementation and sustained growth for its partners.

Challenges

The transition from internal combustion engines (ICE) to battery-electric drives has become a critical focus for Original Equipment Manufacturers (OEMs) across various industries. This shift is driven by tightening emission regulations and growing customer demand for cleaner, more sustainable technologies. However, the journey to electrification presents significant challenges, particularly for larger machines such as construction equipment, Outdoor Power Equipment (OPE), and light motorcycles or tricycles.

These machines often struggle with following:

In finding electric motors and controllers that meet their unique requirements.
Existing electric drive solutions are frequently heavy, inefficient, and too bulky to fit within the compact designs of many modern machines.
As OEMs develop their next generation of electric machines, they seek to overcome the limitations of their first-generation products, such as insufficient power density and system inefficiencies.

Technology Overview

To enable OEM’s to overcome these challenges, ETA has adopted advanced simulation tools, enabling the company to deliver high-performance electric motor solutions efficiently and confidently. Leveraging a comprehensive suite of Ansys solutions, including Ansys Motor-CAD, Electronics Enterprise, Ansys HPC, Ansys Mechanical, and Ansys CFD, ETA ensures that every aspect of solution performance is rigorously validated. Simulation provides:

Validation and Confidence: Proves the technology will meet performance requirements before investing in costly manufacturing processes.
Reduced Development Time: Speeds up solution development cycles by eliminating the need for extensive physical testing.
Risk Mitigation: Identifies and eliminates potential structural weaknesses early in the design phase.

Case Study: Shock-Load Simulation for Commercial-Grade Lawnmowers

A critical aspect of ETA’s business involves designing and developing motors for commercial-grade applications, including lawnmowers. One of the key risks these products face is the impact of sudden stop events, such as when a rotating blade strikes debris during operation.

To address this, ETA collaborated with EDRMedeso to analyze the effect of a shock load caused by such a collision. The goal was to assess the induced loads and identify potential structural integrity issues, using a simulation approach applicable across ETA’s solutions.

1. Scenario Setup:

A 520mm commercial-grade lawnmower blade, typical for these applications, was modeled.
The blade was simulated at a rotational velocity of 3000 r.p.m., representing normal operating conditions.
The system included full contact between components such as the motor, bearings, and debris (modeled as a steel tube).
Ansys optiSLang: for evaluating parametric design changes through the software’s robust analysis capabilities.

2. Boundary Conditions:

Appropriate boundary conditions were applied to simulate the motor’s real-world installation.
The rotor, bearings, and blade were fully integrated into the model, ensuring accurate load transmission representation.

3. Tool Used:

Ansys LS-Dyna was employed for the simulation. This software specializes in analyzing complex, dynamic events like shock loads and impacts.

4. Key Observations:

The simulation showed the blade deforming significantly upon impact with the debris.
The resulting shock load propagated through the system, deforming the motor’s upper bearing and causing one of the ball bearings to release.
The analysis provided detailed insights into how such catastrophic events could impact the motor assembly.

Image giving scale indication.

Benefits of Simulation

1. Risk Mitigation

The analysis revealed potential mechanical failure points, enabling ETA to propose design changes for their motors in this type of application or introduce mechanical interfaces that absorb or mitigate the effects of such shock loads.
This proactive approach ensures and enhances machine reliability, offers right-first-time designs and ultimately reduces rework and inefficiencies.

2. Time and Cost Efficiency

By replacing extensive physical testing with simulation, ETA accelerated the development process and reduced costs.
The ability to simulate multiple scenarios ensures faster iteration cycles, allowing solutions to reach the market sooner.

3. Enhanced Design Performance

Simulation allows ETA to optimize its motor designs, ensuring they meet the demanding requirements of numerous commercial-grade applications.

4. Industry-Specific Insights

The findings validated that ETA’s designs withstand the challenging physical demands of OPE applications, giving clients confidence in the robustness of their solutions.

A blade animation.

Key Observations

The simulation is based on mower blade compliance tests, which involve inserting a steel stake into the path of a rotating blade.
The simulation presented does not include the mower body in which the blade would typically be enclosed.
Upon impact with the stake, the blade undergoes significant deformation, and the motor shaft bends. Deformation is acceptable as long as no debris escapes from the mower.
The shock load propagates through the system, deforming the motor’s upper bearing and causing the release of one of the ball bearings.
The analysis provides detailed insights into how such catastrophic events could affect the motor assembly and identifies potential remedial changes before finalizing the design.
The simulation demonstrates successful compliance within the legislative tolerances required for this application.

Conclusion

Vector By collaborating with EDRMedeso and leveraging tools like Ansys LS-Dyna, ETA successfully identified and addressed potential risks, enhancing the performance and durability of its motor solutions.

Simulation has become an integral part of ETA’s development process, enabling the company to remain a leader in the electrification of machinery and vehicles. By combining industry expertise with cutting-edge technology, ETA continues to empower its clients with solutions that not only meet but exceed the evolving demands of the market.

Learn more about ETA Green Power