How do fanless power supplies dissipate heat?

Fanless power supplies (Fanless PSUs) are designed to operate without the use of mechanical fans for cooling. Instead, they rely on advanced passive cooling techniques and efficient design to maintain effective heat dissipation and stable performance. This article provides an in-depth look at the principles of passive cooling and its application in fanless power supplies.Let's look forward to Owon's upcoming SPS fanless power supply.

Passive cooling relies on thermal conduction and natural convection to dissipate heat. These two mechanisms work together to efficiently transfer heat from the internal components of the power supply to the external environment.

Thermal conduction is the process by which heat is transferred within a solid material from a high-temperature area to a low-temperature area. In fanless power supplies, heat-generating components (such as power converters, MOSFETs, and inductors) are connected to heatsinks made of high thermal conductivity materials, like aluminum or copper. These materials quickly absorb and transfer heat, preventing heat buildup at the source.

Natural convection involves the movement of fluid (air or liquid) caused by temperature differences, which carries heat away. In fanless power supplies, heatsinks transfer heat to their surfaces, which is then dissipated into the surrounding air through natural convection. Heatsinks are typically designed with fin structures to maximize surface area and enhance natural convection efficiency.

●Large Heatsinks: Fanless power supplies often use large heatsinks to increase the surface area for heat dissipation. These heatsinks are typically made of high thermal conductivity materials such as aluminum or copper to ensure rapid heat transfer.
●Fin Structures: The fin design of the heatsinks significantly increases the surface area, optimizing air flow paths and enhancing natural convection. This design allows the heatsink to effectively dissipate heat into the air.

●Optimized PCB Layout: The printed circuit board (PCB) layout in fanless power supplies is meticulously designed to minimize thermal interference among heat-generating components. By spreading out high-heat components and optimizing thermal paths, heat can be effectively conducted to the heatsink.
●Enclosure Design: The enclosure of a fanless power supply not only provides physical protection but also assists in heat dissipation. Metal enclosures can act as part of the heatsink, conducting heat to the external environment.

●Silent Operation: The absence of a fan eliminates noise, making fanless power supplies ideal for environments where quiet operation is essential.
●High Reliability: Without mechanical fan components, the likelihood of failure is reduced, enhancing the overall reliability and lifespan of the power supply.
●Low Maintenance: Fanless designs reduce the need for cleaning and replacing fans, lowering maintenance costs and efforts.
●Dust and Water Resistance: Fanless power supplies typically have better sealing, protecting against dust and moisture, and making them suitable for harsh environments.

●Limited Cooling Capacity: The efficiency of passive cooling is limited by the performance of natural convection and thermal conductive materials. In high power density and high ambient temperature scenarios, cooling capacity may be insufficient.
●Design Complexity: Fanless power supplies require meticulous design of thermal paths and component layout, increasing design complexity and cost.

Fanless power supplies utilize passive cooling technologies to achieve efficient heat dissipation and stable operation without the need for fans. Their silent operation, high reliability, and low maintenance make them suitable for various applications. Despite some challenges, optimizing heatsink design, employing heat pipe technology, and comprehensive thermal management strategies can significantly enhance the cooling performance of fanless power supplies, meeting the demands of diverse application scenarios.