Learn more about electric motor performance, it’s testing and research

July 28, 2021

A recent Virtual UAV Manufacturers Meet Up, organized by MicroPilot, provided its audiences with two days of webinars and discussions on subjects most relevant to the industry, and ePropelled was a proud participant.  

Our Global CTO and MD, Dr. Nabeel Shirazee, presented a session entitled “Demystifying Electric Motor Performance Data.” The session focused on the main aspects of building propulsion motors without forgetting that what to some might seem insignificant, can actually have a huge impact on UAV performance. 

The basics 

The main points of the session addressed questions such as: 

  • What do performance curves really tell you? 
  • How are operating temperature and altitude interrelated? 
  • Why may power to weight ratio be more important than weight alone? 

Using examples from our own in-depth research and detailed data, Nabeel explained why mission parameters are vital to design decisions. Because they not only determine the payload requirements and the overall size of the vehicle, but they also demand different motors and propellers used at different voltages. Among others, designers need to determine: 

  • what propeller to use, 
  • what motor to use, 
  • what air motor controller to use, 
  • what voltage to use,
  • what battery to use, 
  • how peak power differs from continuous power, and 
  • how to use performance curves for the most efficient systems. 

As a result, the propulsion system must be configured to support various requirements and answer all the questions above (and more) for best performing motors. The problem is that minute details of the design can be very complex and have a significant impact on the UAV efficiency. Nabeel used examples and data from our own research to show how designers can balance competing demands of their products’ performance needs.   All the data presented in the webinar was based on solid and in-depth research from:  

  • ingress protection testing (solid and liquid ingress protection) 
  • gyroscopic force testing, and 
  • life testing. 

Higher thrust is not the answer 

One of the main points of the webinar was the fact that many customers focus on thrust, but simply choosing higher thrust doesn’t mean better efficiency. Designers need to find a happy medium where they can marry high efficiency with a lower voltage. And that is always about the mission profile. If, for example, the drone needs to go fast and immediately return at high speed, then the propeller size and voltage will be different than if the mission is not as demanding. 

The conclusion was threefold:  

The most important parameter is not higher thrust. Instead, it’s about better system thrust efficiency—how many grams of force are required per Watt. This is important but easy to forget. Heavier motors do add to the overall UAV weight, but sometimes a heavier motor might be more efficient and provide more force per Watt.  

The second most important parameter is performance requirements. For example, if lower internal temperatures are required, a smaller propeller will be needed. It’s not just a question of finding the right size of the engine and the right thrust efficiency.  

Thirdly, every application is unique and requires data analysis. Designers need to know how every part of their motor functions under different conditions and base their decisions on that. And Nabeel has a vast amount of analytics to share.  

Nabeel holds degrees in electrical and electronic engineering and in magnetic engineering. He earned his Ph.D. at Cardiff University, where he developed a permanent magnet lifting system that the university patented. His interest in magnetics and materials science is pushing his research and his work forward and we were very proud that he could present some of his work during the webinar.  To learn more, watch this free webinar here.