Is it possible to optimise the wound stator design in a high efficiency motor? And how far can this process go? To what end?
These are the questions that I asked myself when faced with a request from the Came Production Manager. The request was clear: come up with a substantial change to a historical customer’s product, indeed a family of products, in order to reduce the cycle time and thereby increase production efficiency, of course with the same motor performance and product cost.
The aim of this service is to find a solution that can optimise a product, and it is divided into two processes:
- Optimising product consumption (electrical efficiency)
- Optimising the product through industrialisation (product efficiency)
In this article, I will focus on the study of an IE3 three-phase motor winding:
Mec 90S/B5 1.1kW 230/400V 50Hz IE3 motor
- The project was divided into two phases:
- Winding design specifications
- CAD simulation of the motor and study of an alternative
1. Winding design specifications
The stator consists of a classic 135×80-36c 4-pole three-phase asynchronous winding.
The most critical design choice was the winding pattern (1-8-10-8 pitch), which offers an electrical efficiency benefit because of its lower phase resistance.
The main disadvantage of this distribution is unfortunately that it is more difficult to make than the better-known concentric winding pattern (1-8-10-12 pitch), especially the phase insulation, resulting in approximately 15% lower production efficiency.
The aim of this study was to assess the possibility of developing a concentric pitch motor with the same performance while not increasing the final product cost.
2. CAD simulation of the motor and study of an alternative
In this second phase, collaboration with SPIN Applicazioni Magnetiche and CAD simulation with FluxMotorTM allowed us to characterise the current model and verify the efficiency loss with the classic pattern shown below, for the same data and materials.
The simulation results are shown below, and indicate an efficiency loss of 1%.
- The efficiency reduction with the new winding pattern could be recovered in several ways:
- Using laminations with lower losses
- Increasing the copper fill factor
- Increasing the bundle height
We ruled out using laminations with lower losses due to price and availability, and focused on changing the other two aspects of the design. After some simulations, this resulted in:
- Increasing the copper volume by +5%
- Increasing the bundle height by +4,5%
- Restoring the efficiency to its original value of 84,3%
The higher raw material cost is largely offset by the higher production efficiency, with net final winding cost savings estimated to be approximately 2,5%.
The result might seem insignificant, but it has a great impact in terms of increased production capacity. This allows Came to respond more effectively to the ever-increasing market demands with alternative solutions without increasing the product cost.
Teamwork, availability of internal and external expertise and professionalism: these are the key factors that have successfully led to the required goal.