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Gallium Nitride (GaN) and Silicon Carbide (SiC) are emerging as key technologies in the power electronics landscape, competing with traditional silicon-based devices such as Insulated Gate Bipolar Transistors (IGBTs) and Metal-Oxide-Semiconductor Field-Effect Transistors (MOSFETs).
GaN devices operate at higher frequencies due to their rapid switching capabilities, however it is currently only applicable to lower voltage applications. It is therefore being utilized in applications where space is limited, enabling smaller, more efficient power supplies. We are seeing this crop up with some consumer brands, for instance Anker's GaNPrime chargers.
Image Source: Anker
SiC also offers fast switching (albeit not as fast as GaN) but it is able to operate in higher voltage applications. SiC also has better thermal conductivity allowing it to operate at higher temperatures without significant degradation - making it great for harsh environments. It is therefore being adopted for use in EVs and Energy conversion systems. Whilst it is not yet being used widely for marketing to consumers there is evidence across the EV industry of adoption either today or planned:
It should be noted that both IGBTs and MOSFETs remain in widespread use today, but as the new technologies improve and also reduce in cost, we are slowly seeing them replaced. Further manufacturing improvements are likely to increase the speed of adoption.
While these devices are more efficient resulting in less power loss and they can operate at higher temperatures without degradation, they come with one clear challenge: their compact size results in increased heat density. This increased heat flux is making more traditional, typically passive cooling systems less feasible for cooling next-gen systems. Therefore engineers are looking for new methods to cool these electronics effectively in order to realize the benefits the technologies offer.
When moving beyond passive conductive heat sinks reliant on natural convection there are a few obvious solutions to consider:
When comparing solutions, particularly those used in applications where there are many cooling needs, I think it is important to consider combining or replacing cooling systems. In other words do you want the system to operate independent of other systems or in combination with them.
Forced Convection
Obviously using larger fans, with potentially a larger fin stack will improve performance, but the drawbacks are obvious; it takes up more space, it uses considerably more power it provides a maintenance risk. Conducting the heat over a larger fin stack can also be tricky, particularly if steel or aluminum are being used to avoid copper due to cost. Embedding two-phase cooling inside using a heat pipe heat sink is a viable option that many engineers have deployed for many years.
Single-Phase
Often in EVs for instance there is a WEG (Water Ethylene Glycol) or Oil circuit. While it may seem straightforward to bring WEG or Oil directly to an inverter system for cooling, it is not always the best solution. I have already mentioned the increased heat flux of new technologies, in practice this means a limited surface of exchange. This means that the existing cooling system will need a higher flow rate and therefore a larger pump. The pressure drop from pumping liquid through small channels to small devices, especially when combined across the myriad of systems in an EV results in a very complex system, requiring many controls to operate effectively.
Two-Phase
With a two-phase system you have the option to combine it with existing systems, including WEG, or create a standalone dedicated cooling system for a component. This can be an extremely effective method for simplifying your global cooling loop, and allowing the two-phase system to both handle the hot components, and bring the heat to a large surface of exchange. Extra emphasis here on the large surface, this means much less pressure drop (in one case of ours over 90% reduction) and less flow rate, simplifying the system and reducing the pump requirements.
For standalone systems two-phase loop systems can be used to drastically improve the transport distance of heat, again allowing it to be dissipated over a much larger fin stack. This is important for solar inverters where the idea of introducing an active liquid cooled loop is not ideal.
Obviously isolated systems or those being used in combination bring the ever-present benefits two-phase offers:
Comparison
We believe that two-phase offers a great combination of benefits for end users that warrant exploring new types of solutions. There are two clear wins:
Calyos was able to significantly reduce the cost of a total system, simply through better cooling. By lowering the system’s thermal resistance, and increasing the efficiency of the IGBTs the client reduced the number of modules required - leading to significant cost savings as these are the most expensive component.
With no pumps or fans involved, our solution not only eliminates noise but also drastically reduces maintenance requirements, making it ideal for traction applications where reliability is key. The solution also reduced the thermal swing experienced by components, increasing their lifetime.
Industrial and Energy systems often demand high cooling performance at low cost and weight. Calyos has developed a new, 100% aluminum loop thermosiphon solution, tailored for these applications.
It can dissipates up to 2kW of high heat flux (100W/cm²) thermal power per module, while remaining lightweight and cost-efficient, thanks to an all-aluminum design. Plus it can be easily scaled to meet the size of your application.
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Who We Are
Calyos is a leader in the design and manufacture of two-phase thermal management systems. Building on our heritage from Euro Heat Pipes (EHP) and their space technology expertise, we specialize in innovative cooling solutions that tackle the thermal challenges of tomorrow.
What We Do
We engineer advanced cooling technologies, including loop heat pipes, micro-channel heat pipes, and pulsating heat pipes, to optimize thermal performance across a variety of applications. Typically these include: power electronics, processors, and batteries, but we don't stop there we are continuing to develop and produce fully customizable solutions for other specific needs, for example e-motors and fuel cells.
Where We Operate
Calyos is headquartered in Charleroi, Belgium, where our engineering and production teams work side by side in a state-of-the-art facility. From this base, we serve a global clientele, providing our cutting-edge solutions across North America, Asia, Europe, and South America.
When We Started
Calyos was incorporated in 2014 as a spin-off from Euro Heat Pipes (EHP), which was established in 2001 and has become a major player in the European satellite market. Since then, Calyos has been adapting and evolving EHP's space-grade cooling technologies for terrestrial applications.
Why We Matter
Our mission is to lead the industry towards adopting the most effective and sustainable thermal management solutions. We aim to address the most pressing thermal challenges in the data-driven and electrified environments of today, leveraging passive cooling technologies to achieve superior efficiency and environmental stewardship.
How We Succeed
Our success is driven by our commitment to four core values:
1. Applied Knowledge - Transforming deep technical expertise into market-ready solutions.
2. Better Together - Emphasizing collaboration with all stakeholders to enhance our collective success.
3. Inherent Flexibility - Adapting our solutions and practices to keep pace with evolving market demands.
4. Continuous Research - Persistently innovating to maintain our leadership in thermal technology.
Ben Sutton
Marketing & Business Development Manager
