What Are Switching Converters And SMPS Transformers?

Switching converters are power conversion devices that utilize high-frequency switching to regulate input voltage, delivering a stable output voltage or current. SMPS (Switched-Mode Power Supply) transformers play a vital role in these systems by stepping up or down input voltages and efficiently transferring energy to the load. These transformers are commonly used in electronics, communication systems, and industrial automation to ensure reliable power and efficient energy conversion.

What is an SMPS Transformer?

An SMPS transformer is essential in a switching power supply for providing galvanic isolation. In an isolated power supply, the SMPS transformer creates a distinct barrier that prevents dangerous high voltages from reaching the output, ensuring safety against electrical shock. However, a downside of an isolated power supply is its lower efficiency and larger size. Non-isolated SMPS units can achieve efficiencies exceeding approximately 95%, while isolated power supplies typically range from 70% to 90% efficiency.

The reduced efficiency of an isolated SMPS is attributed to the SMPS transformer included in the design. When these power supplies operate at high voltage and current, they induce strong magnetic fields within the transformer core. As the input AC signal fluctuates, hysteresis occurs in the magnetic cores of the SMPS transformers. There is a risk that the transformer core may saturate during operation when the input current is particularly high, which results in increased hysteresis and heat dissipation within the core.

Manufacturers of SMPS transformers and core materials typically provide hysteresis curves with their products, enabling designers to assess the limits on input current. Isolated SMPS units with lower efficiency tend to reach higher temperatures when operating at high voltage and current levels, necessitating thermal management strategies to dissipate heat. In high-output power supply units, heat sinks are commonly employed along with chassis-mounted fans to ensure adequate cooling.

How Does a Switch Mode Power Transformer Work?

Switch mode power transformers provide an efficient way to convert AC main power into DC output voltage. When powered on, the AC main supply is filtered through a capacitor before being converted from AC voltage to unregulated DC voltage. In many cases, a regulator is also employed to transform the unregulated DC voltage into a stabilized DC output at a specified level.