TMC Transformers closer to the real world with multiphysics simulations
When looking for the right transformers and dry inductance to meet standard requirements yet also match specific requests, TMC Transformers SpA is the perfect choice.
Founded in 2017 following the acquisition of preexisting know-how, TMC gained in prominence on the market in just a few years due to its expertise and ability to meet customer needs, especially in very specific industries such as marine & offshore, wind, and rail.
Our solid team of about 250 experts are committed to innovation and quality (most are employed at our Italian headquarters in Busto Arsizio).
Flexibility and agility when answering customer requests are two unique features of this young company, which is appreciated for expertise that makes it competitive with major established companies. The numbers are also proof of our customer satisfaction: since 2017, turnover has grown exponentially, even during the pandemic.
A transformer for every need
Today’s transformer market is focused on two primary requests: machine efficiency, implying low losses, and market costs, which need to be restrained.
“These two characteristics cannot be overlooked,” explains Salvatore Iovieno, an engineer in the TMC technical department and an expert since 2004 in multiphysics simulations with finite elements.
“Then there are those industries with specific requests and needs that require specific raw materials or transformers optimized for custom parameters such as circuits and geometry.”
This is the difference of TMC: offering highly customized applications. “We develop nonstandard solutions with high levels of personalization. For example, transformers with one primary winding and 27 secondaries, solutions with a 52-kV voltage class and highly strict phase shift angles. Alternatively, for new applications, we offer clients innovative solutions in terms of materials and structures.”
Simulations, an essential tool for designing quality
Given the above, it is clear why simulations are an essential element in transformer design. The more complex an object is or the more it deviates from standard construction, the more important it is to simulate its real operation according to the required conditions. Since transformers are subject to physics in the real world, multiphysics simulations are perfect for approaching the actual operating conditions.
In particular, which physical forces should be considered?
“Transformers are often perceived as machines in which the fundamental physics are electromagnetic. This is true, but transformers are extremely complex machines in which more interconnected physics operate,” Iovieno explains.
For example, electricity moving through the windings causes the machine to heat up, and it is essential for a good design that the temperature spreads across the various parts of the transformer (i.e. core and windings). It is also necessary to know how these parts react to temperature increases.
Although transformers do not contain moving parts, mechanical and structural analysis is necessary to ensure the tightness of the windings in case of short circuits.
Closer to reality with finite element multiphysics analysis
The most advanced multiphysics simulations are finite elements analysis. As Iovieno explains, the simulation creates a “mesh” for each component and geometry, discretizing the component in question.
“In this step, under precise instructions from the operator, the software divides the component into many subsets and the differential equations that describe the physics in question are applied to each. In the case of electromagnetism, for example, Maxwell’s equations, which constitute the fundamental rules that govern electromagnetic interactions, are applied to each discrete element. Finite element simulations provide an extremely precise analysis of the component and define the gradients of each type of physics considered.”
For transformers, the most common properties investigated using multiphysics analysis are electromagnetism, mechanics, and thermal physics.
The added value of multiphysics simulations
In developing TMC products, multiphysics analysis is involved right from the offer, which determines the technical specifications requested by the customer. Therefore, right at the beginning, it is possible to understand if the suggested geometries are the most suitable and they need to be optimized.
“Multiphysics analysis is very useful if there is any need to exclude design paths that are not practicable in view of the simulation results.” Customers also appreciate multiphysics simulations.
“We use the example of a transformer that must guarantee short-circuit withstand. To be sure that the machine matches the requirements, the customer might ask for a test that would be commissioned to certified third-party laboratories, but this also implies a further significant cost. With multiphysics analysis run on finite elements, we always provide the customer with a very detailed report of the analysis, which provides evidence and guarantees that the machine has been designed to answer the specific request for short-circuit withstand, often making the test irrelevant.”
This type of analysis brings added value to both the company, which offers products developed on a sound scientific basis, and the customer, who is guaranteed that the TMC product meets its requirements, is made with cutting-edge tools, and is the result of top-quality analysis.
What if new parameters that are not yet covered by the analysis software need to be analyzed?
“The companies developing multiphysics analysis software are very attentive to customer requests. Whenever we have to consider new parameters that have not yet been implemented in the software, the developer, upon request, quickly integrates the additional functions. Simulation software programs develop based on user needs. Besides this, we have also witnessed many improvements concerning the use of storage and computation times over the years. For example, the same analysis that required many hours of machine computation time just a few years ago can be solved in a few tens of minutes today. Advances in software have been truly decisive.”
Although they are powerful tools in and of themselves, multiphysics simulations integrate very different skill areas. Moreover, user experience plays a key role when performing the analysis.
“For instance, choosing the best discretization of the component, namely the one permitting the best visualization of the force gradients acting on it, is also the outcome of previous experiences that have taught us where such forces are exerted, and which points should be considered in further detail. Since there is no such thing as standardization, every company builds its own know-how and skills based on the experiences and the analysis made when developing the various products. Such know-how is the real business tool used to make further developments.”
One analysis for three types of physics
One of the most recent cases for which TMC conducted complex multiphysics analysis of the finite elements was a railroad substation transformer with two secondary windings operating in connection with a 12-impulse frequency converter which had provide a specific short-circuit withstand.
“In this case, finite element analysis highlighted the current thickening at either end of the conductors at various operating frequencies, a detail that led to optimization of the conductors themselves. Such analysis highlights the density of losses which lead to heating in various parts of the transformer and calculates the temperatures via thermal simulation. For the same machine, mechanical simulations were also conducted to guarantee short-circuit withstand. A detailed technical report of all the above analysis was prepared and provided to the client as further guarantee of product quality.”
At TMC, multiphysics analysis of finite elements has been applied since day one. From the beginning, TMC has used the software Comsol Multiphysics®, which is suitable for modern technological challenges and is based on the most advanced numerical methods.