How do you protect and cool power electronics components in harsh environments and high temperatures?

Power devices fail when they exceed a specific junction temperature. Even if the temperature is below the maximum limits it is likely that the functionality of the device may be curtailed by derating. Thermal management starts with optimizing the topology for minimum power losses. The selected components must have adequate thermal headroom to account for changes in ambient temperature and worst case power loss scenarios. This is supplemented by adding convective or forced induction cooling (air or water). The selection of a cooling system also depends on the type of application - A standalone system deployed in a remote area may benefit from the simplicity of convective type cooling while more complex automotive systems need water cooling.

May be it is time to carry out detailed research studies on different Indirect Cooling Methodologies, using Thermal management Systems - This opens up an entirely new field of Cooling research opportunities for Power Electronics based Power Converters and Power Components at high altitudes when the air density is low with lower breakdown strength - This an extremely important portfolio of research to explore for Aerospace applications - Thermal Engineering plays a vital role for this kind of Cooling Methodologies - New materials, New Cooling techniques with less weight to provide High Power density and High Specific Power levels for Power Electronics Converters and Inverters along with High Power Motors

Aerospace power electronics cooling is especially challenging as air, and liquid cooling may not be viable techniques due to the operating environment. In deep-space applications, conductive and radiation cooling is a better alternative. If isolation standards are respected, PCBs can utilize multiple copper pour polygons as heat sinks. Thermal jumpers are also useful to connect live planes to MOSFET cases to ensure effective thermal management.

In power electronics, the focus is not just on cooling components, but also on extracting heat in a beneficial manner. We are working on a method termed "concentrated heat extraction." This technique revolves around focusing the extraction of hot air, facilitating its channeling through pipes to heat pumps. Utilizing this warm air enhances the efficiency of heat pumps and cuts down on overall energy expenses.

In the world of power electronics, the focus is often on electrical efficiency and component performance, but how often do we discuss the importance of mechanical design? The truth is, well-executed mechanical design not only complements electrical performance but significantly enhances it. About Thermal Management: Power devices generate significant amounts of heat. A design that integrates efficient cooling solutions, such as liquid cooling systems or optimized airflow designs, can make the difference between a device that fails and one that exceeds expectations. Effective thermal management is not just about keeping components cool—it’s about ensuring reliability, safety, and sustained performance over time.

Although protective coatings are advantageous, they can add weight to the application, eating away at the power density specifications advertised before the coating is applied. Also, when subjected to high voltages, air bubbles trapped in the insulation coating exhibit arcing and corona discharge phenomena, making the coating susceptible to failure. Coatings used in aerospace environments have additional specifications, including thermal cycling stability and outgassing susceptibility. Outgassing is a phenomenon where an insulator breaks down when subjected to radiation, causing gas emission, leading to dielectric failure.

Real time temperature sensing of all the power semiconductor switching elements can help optimise the thermal management. When there are more than one path for power flow, all paths should be equally stressed by using the above mentioned thermal sensing data. When load is less, only absolutely essential power flow path can be enabled and this selection of power flow path should be on rotation basis. For example, when there are parallel phases in operation, by looking at the thermal sensing data, PWM should be controlled in a way to reduce the thermal stress. Also, under each less load conditions, a different phase can be enabled on rotation basis.

Accurate thermal modelling of power electronics is the key to arrive at best thermal management strategy. Using Cauer or foster networks, heat dissipation and the thermal resistance can be modelled in simulation and accordingly heat sink/ cooling system can be designed and tested in simulation environment. Natural air cooling, forced air cooling, oil cooling are some of the examples of cooling systems. Each system has its own parameters for example for liquid cooling, thermal resistance and flow rate are the key points to consider while designing.