aegis Power Systems, a leading provider of power supply solutions for industrial, commercial, and military sectors, has crafted a detailed technical article that explores various cooling techniques utilized in AC-DC and DC-DC power supplies.
All electronic devices produce heat, which means they cannot operate at 100% efficiency. To prevent damage and enhance reliability, each unit must effectively dissipate excess heat. This process is known as thermal management, commonly referred to as cooling.
There are multiple strategies to reduce losses in power supplies through diffrent cooling methods. The efficiency and reliability of a power supply unit are significantly influenced by its cooling design.
This article provides an overview of the most prevalent conduction and convection cooling techniques for AC-DC and DC-DC power supplies.
Heat Sink Technology
Heat sinks represent a form of conduction cooling, facilitating heat transfer through direct contact with a cooler component within the unit.
In technical terms, heat sinks are categorized into two main types: those equipped with fins and those without. However,in engineering terminology,“heat sinks” typically refer to finned varieties,while “cold plates” denote the non-finned versions.
Finned heat sinks enable rapid heat dissipation due to their increased surface area in contact with air and are frequently enough paired with forced air cooling for optimal performance. However, design limitations related to space ofen restrict this option to medium to large applications.
Cold Plate Solutions
Cold plates serve as another conduction cooling method,utilizing a thick metal plate to draw heat away from a unit.
Cold plates are especially effective in scenarios where simplicity and space are critical factors. Nevertheless, the overall design must also incorporate a mechanism for heat dissipation from the cold plate, which may involve natural airflow, thermal compounds, or forced air systems.
Liquid Cooling Systems
Liquid cooling involves a specialized cold plate that contains a closed-loop system of cool liquid, which can be water or a 50% water and 50% glycol mixture in our applications.
This method maintains a consistent temperature at the base plate, ensuring efficient thermal transfer. Liquid cooling is ideal for compact spaces where traditional heat sinks and fans are impractical. For instance, it is widely used in aircraft due to stringent size and weight constraints. Ground vehicles also benefit from liquid cooling; our 600E power supply for electric vehicles exemplifies this application.
while liquid cooling is highly efficient, it comes with increased costs and complexity, requiring more materials and engineering resources to integrate into power supply designs.
Enhancing Heat Transfer with Thermal Compounds
Thermal compounds, though not a standalone cooling method, significantly enhance heat transfer between a heat sink or cold plate and the unit. Also known as thermal paste or thermal grease, these materials are thermally conductive and ensure even adhesion between components.
Natural Airflow: A Cost-Effective Solution
Natural airflow, technically referred to as convection cooling, dissipates heat by surrounding the unit with cooler air. If the unit is enclosed, air vents may need to be incorporated into the design to facilitate circulation.
This method is often the most economical thermal management option and tends to yield the best mean-time-between-failures (MTBF) ratings due to the absence of additional mechanical components for air movement. Though, power supplies relying solely on natural airflow face meaningful limitations in their safe operating temperature range.
For demanding applications such as aircraft, industrial robotics, and maritime systems, natural airflow is typically insufficient for cooling the associated power supplies.
Forced Air Cooling: An Enhanced Approach
Forced air cooling is an advanced version of natural airflow thermal management.
This technique incorporates one or more fans either within the unit or specified elsewhere in the application’s design to ensure adequate cooling for the power supply, thereby achieving maximum rated output. Aegis’ HY2714A COTS DC-DC converter exemplifies a power supply that utilizes customer-supplied forced air cooling.
It is vital to note that while fans improve thermal management,they can also contribute to the inefficiency of the unit. However, they may help reduce internal dust accumulation, enhancing the overall effectiveness and lifespan of the power supply.
Choosing the Right Cooling Method
Each cooling technique offers distinct advantages for thermal management in various power supplies. Typically, the cooling system is steadfast by customer specifications during the initial design phase. In manny cases, a combination of several cooling methods may be employed.
Global initiatives aimed at enhancing energy efficiency have prompted engineers to innovate in cooling power supplies, even though progress has been gradual. Aegis engineering manager Mark Mason notes, “While 99% efficiency may be attainable, achieving it may not occur in our lifetime. A 100% efficiency rate is, of course, physically unfeasible.”
Despite this understanding among engineers, the pursuit of optimal efficiency remains a driving force across all industries.
As an exmaple, the Aegis LMA501 DC-DC converter has achieved the highest efficiency of any Aegis unit to date, boasting a typical efficiency of 93%. This allows for energy savings in other areas of the supported application, freeing up budget for additional design elements.
Several factors influence the choice of cooling method for your power supply design, including space constraints, efficiency, cost, weight, and the amount of heat generated.
For reliable and efficient power supplies, visit Aegis Power Systems and request a quote for a custom design.
