TMC Transformers closer to the real world with multiphysics simulations
When you need to find the right transformers and dry inductance to not only meet standard requirements, but also match specific requests, the right choice is TMC Transformers.
Founded in 2017 following an acquisition in which it acquired the pre-existing know-how, TMC in a few years TMC established itself on the market in just a few years due to its expertise and ability to meet customer needs, even in very specialized industries such as marine & offshore, wind, and rail.
Our team of approximately 250 specialists, experts committed to innovation and quality approximately 250 (the majority located in at our Italian headquarters in Busto Arsizio), makes the company solid.
Flexibility and agility in answering the client requests are two peculiar characteristics of this young company, which is appreciated for expertise that is in no way inferior to major established companies. Customer satisfaction is visible also visible in the numbers: since 2017, the turnover of TMC has grown exponentially, even during the pandemic.
A transformer for every need
Nowadays, the transformers market is focused on two main requests: the machine efficiency, implying low losses, and the 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 that are optimized based on tailored parameters such as circuits and geometry specific raw materials."
This is where TMC makes the difference, 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
Based on the above, the reason why simulations is are an essential element in transformer design is clear. The more complex an object becomes and/or deviates from a standard construction, the more important it is to design it while simulating its real operation according to the conditions required. And since transformers are subject to physics in the real world, multiphysics simulations is needed to get closer to reality.
In particular, which physical forces should be considered for transformers?
"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 for a good design, it is essential to see the temperature spread across the various parts of the transformer (i.e. core and windings) and how these parts react to increases in temperature.
Even though transformers do not have moving parts, mechanical and structural analysis is needed to ensure the tightness of the windings in case of short circuits.
Closer to reality with finite element multiphysics analysis
The most advanced level of multiphysics simulations is 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 investigated common aspects investigated using multiphysics analysis are, above all, electromagnetism, mechanics,and thermal physics.
The added value of multiphysics simulations
In the process of developing TMC products, the multiphysics analysis comes into play right from the offer, which is based on the technical specifications requested by the customer. It is therefore possible, even at the beginning, to understand if the suggested geometries are the most suitable and if optimization is necessary.
"Multiphysics analysis is very useful if there is any need to exclude design paths that are not practicable in view of the simulation results." Multiphysics simulation is also particularly appreciated when it comes from the customers.
"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 the 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 to the specific request of for short-circuit withstand, often making the test irrelevant."
Essentially, this type of analysis brings added value to both the company, which offers products developed on a sound scientific basis, and the customer, who has the guarantee that the product provided by TMC complies with its requests, is made with cutting-edge tools, and is the result of top-quality analysis.
What if there is a need to analyse new parameters that are not yet covered by the analysis software?
"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 over the years, we have also witnessed many improvements concerning the use of storage and computation times over the years. For example, the same analysis that a few years ago required many hours of machine time computation time just a few years ago can be solved in a few tens of minutes today. Advances in software have been truly decisive."
What to focus on
Multiphysics simulations, despite being powerful tools in and of themselves, require the integration of multiple competencies which are all different. Moreover, the user experience plays a fundamental role 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 and illustrative cases, for which TMC carried out complex multiphysics analysis of the finite elements, was a transformer for a railway substation 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 the temperatures 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 the "day of its establishment." Since the beginning, TMC has used the software Comsol Multiphysics®, which is suited for modern technological challenges and based on the most advanced numerical methods.