Cost Effective High- Performance Design: Innovation is the Answer

Marelli Motori applies multiphysics simulation to cost-effectively design better, more reliable motors and generators faster

ABSTRACT

Improving efficiency while reducing cost is a very complex engineering challenge. Marelli Motori, one of the world’s leading generator and electric motor manufacturers, makes extensive use of Computational Fluid Dynamics (CFD) and Finite Element Method (FEM) multiphysics simulation to do just that in the design of its electrical motors and generators. It applies CAE to help it achieve the goals of increasing the efficiency and reliability of its products and lowering their environmental footprint as much as possible, reduce the product development costs in order to remain competitive and keep the products “sellable”, while shortening the time to market. In this overview article, EnginSoft engineers describe how the challenge is approached by using multiphysics simulations for all the components of the motors and generators, as well as to the construction operations.

<h5>Marelli Motori</h5>
Marelli Motori

Marelli Motori is one of the world’s leading generator and electric motor manufacturers. The company was founded in 1891 and enjoys worldwide brand recognition thanks to its extended sales, distribution and service networks across four continents. With two manufacturing facilities in Italy and Malaysia, Marelli Motori sells these technologically advanced products in more than 120 countries.
The business model is based on a successful combination of strategic key elements that enable Marelli Motori to offer innovative and inspired solutions to create value for customers: a wide range of innovative products, skilled people to provide sales and global support and continuous investment in R&D.

Entire GenSet model Meshed to realize Modal Analysis

Entire GenSet model Meshed to realize Modal Analysis

OBJECTIVES

Day by day, power generation is becoming more competitive, reliable and eco-friendly. Marelli Motori is focused on innovation, aiming to match the market needs in the hydro, cogeneration, oil and gas, industrial applications, and marine sectors by increasing efficiency and reliability and lowering the environmental footprint as much as possible. 

These targets can’t be achieved independently: improving the overall performance can lead to overly expensive products, making them “unsellable”, so any activity aimed at increasing the efficiency of the machine must be accompanied by cost reduction -- this is the only way to be competitive in a global market.
It was therefore important to develop multiphysics simulations for all the components: structural analysis to evaluate strength and deformation, dynamic analysis to thoroughly study the operating behavior of the machine, and thermal CFD to improve cooling efficiency -- all while reducing the cost of product development and shortening the time-to-market.

SOLUTION 

Numerous ANSYS simulations were conducted to achieve optimal results: structural simulation was done on the frame, shields, fan and shaft to reduce mass while also creating a better design by reducing waste material. In addition, the construction operations were considered, keeping mechanical safety and reliability in the foreground for each potential operating condition.

The rotor assembly (including the fan), the stator and heat exchangers (where needed) were simulated multiple times to find the optimal trade-off point between cost reduction and thermal efficiency. These components are the core of the entire machine’s thermal exchange. Indeed, the subsequent design modifications arose from the structural and CFD calculations intended to increase cooling efficiency and thermal exchange, lower hot-spots inside the generator, and maximize power output. Approaching the job in this way was complex because the aim was to optimize the design of the entire family of components to extract heat from inside the machine, but, at the same time, there were many constraints concerning the feasibility of the individual shapes, the cost of production and the ease of final assembly.

Each component had to pass a structural assessment. In parallel with the process described thus far, the engineers developed dynamic simulations on a sub-group of components, both inside the machine and on the entire assembly.
Modal Analysis to find natural frequencies and the subsequent harmonic responses according to operating conditions was key to analyzing the dynamic behavior of the machine. These simulations ensured the mechanical reliability of the generating set (genset) during the working phase.
With regard to the design of new components and the modifications to existing ones, a drastic reduction of development times was achieved by taking advantage of SpaceClaim’s defeaturing, 3D-modeling and ease of handling geometric parameterization inside a workbench interface which allowed modifications to be managed very quickly.

Entire GenSet model Meshed to realize Modal Analysis

Structural analysis of a Frame loaded with Torque arising from the Stator

Given all these activities already undertaken for product improvement, what other points could be developed in future? This led the engineers to consider the possibility of snapping off dead times during product development.
Often the CAE analysts working on simulations need to leave their workstations to go to the test room, or to another company’s headquarters, or to attend a meeting. This means they cannot follow the progress of computing operations, check the trend of convergence nor modify any parameters. Moving with a laptop is not always feasible, so the easier way is to exploit the most common connection device. This simple idea is based on an ordinary smartphone or tablet connected to a virtual private network (VPN), a dedicated app with notifications about the simulation status, and the ability to manage only key parameters via remote control. Even better if the application sends push notifications for specific events, such as divergence of the calculation, or the completion of a point solution. The development of this concept could mean zero additional device costs and considerable time saved: a rough calculation can demonstrate that the hours saved in a given year would exceed a few hundred.

RESULTS

By applying multiphysics simulation to different aspects of electrical motor and generator design, the best result for each single component was achieved. The combination of Marelli Motori’s expertise and ANSYS software’s capabilities was key to achieving better competitiveness in today’s market.
The project achieved increased efficiency, component cost reduction and reduced development time for different product series. The final results can be synthetized by the ratio “power output  over final cost” which, in many cases, delivered a double-digit percentage improvement.

This engineering simulation project was honored with the “ANSYS Hall of Fame 2017 - Top 10 Commercial entry” award

Nicola Pornaro, EnginSoft | Newsletter EnginSoft Year 14 n°1

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