Primary Challenges for Today’s AC-DC Converters

The equipment that depends on AC-DC converters for power continues to raise the bar when it comes to certain characteristics and aspects of design. Many of the challenges faced by modern AC-DC converters are related to efficiency, heat generation, downsizing, protection functions, and obsolescence.

Efficiency

Higher levels of efficiency, defined as output power/input power, are increasing in demand. Efficiency is related to the power consumed when a device is in standby mode, leading to the challenge of reducing the power draw even when the device is not actively being used. Efficiency is also closely related to size. Typical efficiencies for AC-DC converters are on the order of 80% but can reach up to 95% with the right selection of parts and systems.

Heat Generation

The difference between the input power and output power represents a loss that takes the form of heat generation. Controlling and minimizing heat generation is critical for many reasons, including the damage it can cause to surrounding electronic components. 
 

In the context of industrial AC-DC converters, heat generation is most often addressed through the use of a heatsink to aid in heat dissipation. What’s more, a cooling fan may also be required to keep temperatures at an acceptable level. The necessity of heatsinks and cooling fans further decreases efficiency and increases the size of the system. 

Downsizing

Downsizing is another major challenge for AC-DC converters and involves not just the number of parts but also their size. The need for a small footprint and low part count does lead to more flexibility in installations and reduced manufacturing and shipping costs, but it can be extremely difficult to achieve. And the goal of downsizing is further complicated by the need for heatsinks and cooling fans. 

Protection Functions

AC-DC converters require effective safety functions that support both safety and reliability. There are three basic types of protection functions needed in AC-DC converters:

• Input (over-voltage, input voltage drop with non-functional)
• Output (overload, short circuit, reverse voltage, and over-voltage)
• Temperature (excessive self-heating and increased ambient temperature)

However, including the right protection functions can complicate downsizing and miniaturization unless a control IC with integrated protection functions is used.

Obsolescence

Another problematic issue faced by engineers and designers is obsolescence. Is the selected AC-DC converter guaranteed for the life of the product? Being forced to do a redesign is serious enough, but doing so because of the obsolescence of an AC-DC converter is even worse. The aftermath of such a redesign is often more extensive than it may initially appear. Not only is another revision of the PCB necessary, but there is a high probability that EMC testing will need to again be performed for the product. This, in turn, means associated paperwork must be resubmitted (and even a complete redo of the safety analysis).
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