IGBT (Insulated Gate Bipolar Transistor) modules are commonly used in various power electronics applications. Typical applications are inverters, converters, motor drives, and renewable energy systems. IGBTs are also widely used in industrial controls for applications such as variable frequency drives, uninterruptible power supplies, and lighting controls. IGBTs are used in high-voltage switching applications to switch high voltages and currents efficiently and quickly. Modern IGBT modules are very powerful. However, the high current density and heat dissipation cause serious problems for the IGBT products, affecting their performance, lifespan, and capability to operate in high ambient temperatures with maximum power. Therefore, proper cooling is crucial for ensuring the reliable operation of IGBT modules.
There are three main categories of cooling methods. Natural convection cooling relies on air circulation caused by temperature differences. It is an economical cooling method suitable for low-power IGBT modules. Typically, natural convection is not an option for powerful IGBT modules due to limited thermal performance. Forced convection cooling offers better cooling efficiency because it uses a fan or blower to circulate air over the IGBT module. It is broadly used with high-power IGBT modules where natural convection cooling is insufficient. Liquid cooling is typically the most efficient method that uses a liquid to absorb heat from the IGBT module and transfer it to a heat exchanger. This method is used in high-power applications where even the most potent air-cooling solutions cannot meet the specifications of the IGBT application.
NEOcore has a clear advantage in IGBT cooling applications
CooliBlade has developed a NEOcore thermal channel for extreme cooling needs. The basic principle of NEOcore can be used in natural and forced convection cases. NEOcore is a fully integrated aluminum-based solution that utilizes the phase change principle. The whole thermal flow is optimized from the evaporator to the condenser and the heat dissipation to air. The extreme heat transfer capability and the low thermal resistance of NEOcore based products make them capable of even the most demanding forced convection solutions, like IGBT cooling. The low thermal resistance allows the operation of IGBT modules with their maximum performance level in harsh industrial environments.
A single IGBT module’s typical cooling power requirement is at the level of a few kilowatts. In many applications, this level of power traditionally requires liquid cooling. The outstanding thermal management performance of NEOcore heat sinks with forced convection makes it possible to handle the excess heat of IGBT without complicated liquid cooling systems. Power density is also setting another critical challenge in IGBT cooling. Thanks to new component and packaging technologies, increased power densities limit the system-level performance of electronics, especially when using traditional aluminum heat sinks. The thermal conductivity of aluminum material is relatively low, only 200 W/mK. This makes a significant thermal gradient in typical IGBT cases to the first thermal interface from the component. NEOcore thermal channel can remove this bottleneck by transferring the heat instantly from the component into the thermal channel and to the whole structure. When utilizing a large evaporator area and only a thin aluminum surface, optimal performance can be achieved at the most critical interface from the thermal management point of view.
IGBT cooling design should address several topics
Several critical design parameters and features should be addressed when the most efficient cooling products are designed. Power dissipation of the systems is usually the first to address. The cooling method must handle the amount of heat generated by the IGBT module during operation at maximum power. As mentioned, the typical power loss of modern IGBT modules is in the kilowatt range. But it is not only power level but also power density that matters. The maximum power level, together with the module size, determines the maximum power density of the system. This should be at the level that the heat sink element can handle. The operating environment can vary quite a bit in different applications. High ambient temperature sets higher demands for thermal management solutions if the maximum performance of IGBT modules is required.
One typical challenge for traditional heat sinks is also their size. Many aluminum heat sinks need to be bulkier for high-power applications. Their weight may challenge device-level designers, while higher weight may create additional challenges for the product layout. More compact and lightweight cooling solutions give electrical and mechanical engineers more freedom in their work. Finally is the cost of thermal management products. This is not only the cost of materials but also the cost of the development project required. CooliBlade has done its best to shorten the development times and investment in the mass production of the designs to find the optimal balance between the initial investment and the price of the final product.
Thermal management trends in the future
In the future, IGBT cooling is keeping its critical role in power electronics design and performance. There are a few emerging trends in IGBT cooling that will show the way for IGBT cooling products. There is a clear trend towards advanced cooling techniques like two-phase cooling and liquid cooling, which provide better thermal performance and improved reliability compared to traditional air cooling. Traditionally this means heat pipes and thermosiphons. NEOcore is a new and fully integrated solution in this segment, and it offers high performance in a compact structure. The role of simulation is becoming even more critical in the future.
Simulation and modeling tools are becoming more used in designing the cooling of IGBT modules and ensuring that they meet the expected performance requirements. Simulation expertise reduces product development time significantly. It is also emphasized by CooliBlade to ensure the fastest and smoothest development cycle for our products.
The integration level of cooling and packaging solutions is increasing. When the size of a component decreases, the integration of cooling solutions plays a more important role in the future. The integration level also greatly impacts the cooling solutions’ performance level. The first interfaces between the component and the heat sink unit are typically the most critical ones from the performance point of view.
Miniaturization of electronics products also sets some new challenges for cooling unit developers. As IGBTs continue to get smaller, there will be a greater emphasis on developing compact and efficient cooling solutions that can effectively handle the increased heat density. NEOcore provides excellent power density capabilities and is the natural way to solve power density challenges.
The evolution of high-power electronics goes hand in hand with thermal management development
Advanced cooling technology innovations are crucial for ensuring performance improvements and the reliability of IGBT modules in demanding industrial applications. The cooling method should be selected based on the power dissipation, operating environment, size and weight constraints, and cost considerations of the application. Overall, the future of IGBT cooling will be focused on improving performance, reliability, and efficiency while adapting to the changing needs of power electronics systems. The development and implementation of next-generation cooling technologies greatly impact the era of electrification in the long run. All the development in the high-power electronics components and packaging can be fully utilized only when the development can go hand in hand with the evolution of thermal management.
If you want more information about the NEOcore technology or cooling solutions in general, don’t hesitate to contact our personnel.
Kimmo Jokelainen
Chief Technology Officer
CooliBlade
