Technology Insights | Triphibian™: Pressure Sensor Technology Revolutionizing Thermal Management in Electric Vehicles

As the problem of climate change becomes increasingly serious, humans must take effective measures to significantly reduce carbon emissions. Under the new legislative and policy framework, the automotive industry is facing unprecedented pressure. Take the "Fit for 55" initiative under the European Green Deal as an example, which proposes to amend laws and regulations to reduce carbon dioxide emissions from new cars, with the goal of reducing emissions levels by 55% by 2030 compared to 2021 levels. The ultimate goal is to reduce CO2 emissions from new cars and vans by 100% by 2035. The implementation of this initiative means that new cars powered by internal combustion engines will be banned from 2035, thus accelerating the popularity of battery electric vehicles (BEV).

However, more solutions are needed to address CO2 emissions from fuel extraction to vehicle driving. Although countries are stepping up the deployment of greener energy sources, they will not be able to provide enough energy to promote the development of new electric vehicles in the short term. Additionally, EV charging infrastructure coverage remains insufficient in many countries, posing challenges for sustainable vehicle solutions.

▲ Illustration of battery-powered electric vehicle thermal management system

In order to achieve higher levels of thermal management efficiency, OEMs and system manufacturers need to rely on accurate, reliable and miniaturized pressure sensing technology that can handle various types of media and accurately measure the pressure of gases and liquids . At the same time, the sensor chip should have anti-freeze properties to avoid damage due to medium freezing during the measurement process.

Thermal management systems in electric vehicles consist of multiple interacting refrigeration and cooling circuits that control the temperature of the cabin and battery pack and cool the power electronics and electric motors. A pressure sensor chip and a temperature sensor chip are deployed in this system to monitor the status of the refrigerant, helping to optimize system efficiency and protect key components from damage.

▲ Melexis BEV thermal management system chip solution

System centralization is the mainstream trend in thermal management of electric vehicles. This technology minimizes weight and piping by tightly integrating more components while improving system reliability and simplifying the installation process.

In 2021, former Ford engineer Sandy Munro (now founder of engineering consulting firm Munro & Associates) took apart the thermal management systems of the Ford Mach-E and Tesla Model Y. Sandy and his team found that Mach-E's thermal system contains 35 components, with a hose length of 18.42m and a weight of 22.4kg. In contrast, the Model Y thermal system shows a high degree of integration and only contains 10 components. The length of components and hoses is 6.35m, and the weight is 9.2kg. There are obvious advantages in the number of components and weight.

“ For automotive OEMs and system manufacturers

Installing pressure sensor chips within components of centralized systems helps reduce potential points of failure within the refrigerant and cooling circuits .”

▲ Triphibian™ sensor chip

Micro MEMS pressure sensitive components provide strong support for this technology direction. The sensor chip has more reliable and accurate characteristics and uses a smaller package, thus significantly improving the performance of the system.

Ten years ago, Melexis introduced to the market the MLX90809 , the first factory-calibrated pressure sensor chip in a rugged package designed specifically for safety-critical applications in automotive braking systems. Since then, Melexis has continued to innovate, and has successively launched highly integrated pressure sensor chips, achieved miniaturization of bare chip products (such as MLX90819/20), and released ultra-high-precision PCB-free automotive pressure sensor chips (such as MLX90822 /23/24/25).

However, MEMS technology has some limitations in the application of electric vehicle thermal management systems. Many existing low-pressure sensor chips, whether with PCB or without PCB, are difficult to withstand burst pressures exceeding 20bar, otherwise the sensor chip may be damaged (such as gel rupture, bonding wire disconnection). Furthermore, there is a risk of separation of the chip from the package when the backside of the relative pressure sensor chip is subjected to pressure, and these sensor chips typically can only measure the pressure of gaseous media.

During use, if the gel side of the sensor chip is in contact with the liquid to be measured for a long time, there is a risk that the liquid will penetrate the gel and cause the output of the sensor chip to drift. While other types of sensor chips can withstand most liquids, they are either unable to cope with liquid freezing or are difficult to miniaturize. For the automotive industry, many existing packaged and bare die MEMS solutions are insufficient.

▲ Comparison of MEMS sensor chip design and its limitations

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Melexis’ Triphibian™ Technology

The Triphibian™ sensing element is an IC package that contains a cantilever with a sensing film at its tip. The sensor chip's cantilever structure remains balanced around pressure during pressure transients and burst pressures, making this design more robust than back-exposed solutions, which are between the glass base side and the wire bond side There is still a pressure difference. The principle of pressure equalization also applies to cryogenic media, which is the first time MEMS has been used in such an environment.

"Melexis provides a pressure sensor solution that is packaged, easy to integrate, factory calibrated and uses innovative technology for automotive thermal management systems. The sensor chip is packaged in SOIC16 and can be electrically connected to the PCB board through a reflow soldering process. connections while making it easy to seal the sensor.”

▲ The design of the MLX90830 eliminates the requirement for initial calibration beyond Melexis factory calibration

MLX90830

The first product in the Triphibian™ product range, it can measure gaseous and liquid media from 2 to 70 bar like never before.

●Measure 2-70bar liquid and gas, and can handle solid state

● Subverting MEMS pressure measurement

Triphibian™

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As the challenges facing the world continue to increase, MEMS pressure sensor chip technology will become an important tool in meeting these challenges. In addition to its application in automotive thermal management, this technology can be applied in many other areas. For example, as the impact of climate change on humanity becomes increasingly apparent and water scarcity becomes a hotly debated topic, Triphibian™ sensor chips can help manage local water consumption, just one example of many potential market-leading applications.

Melexis is committed to making a positive contribution to all mankind and the entire planet and continues to innovate and expand its product lines. Stay tuned for the next product in Melexis’ Triphibian™ series!