Analog/Mixed Signal

Achieving High-Efficiency Power Supplies Without Increasing Complexity or Cost

27 June 2017

In 2004, Ecos Consulting launched 80 Plus, a voluntary certification program intended to promote efficient energy use in computer power supply units (PSUs). 80 Plus certifies products that have more than 80% energy efficiency at 20%, 50% and 100% of rated load, and a power factor of 0.9 or greater at 100% load. Such PSUs waste 20% or less electric energy as heat at the specified load levels, reducing electricity use and bills compared to less efficient PSUs.

The 80 Plus program has expanded since that first specification was implemented. Valid levels now include Bronze, Silver, Gold, Platinum, and Titanium specification level. The chart below lists the requirements a PSU must meet to be certified.

Today, it is critical to have an efficient power-conversion system for various economic and environmental reasons. According to the 80 Plus for titanium specification, efficiency levels required are 96%. This high-level of efficiency poses a serious design challenge for power-supply companies.

One method that can help is exploring different power-factor correction (PFC) topologies. Many manufacturers have been investigating this method and discovered that the totem-pole PFC is attracting more attention because it requires few components, has low conduction loss, and provides the high efficiency needed.

There are many options available for implementing a totem pole topology for PFC. A demonstration system was designed utilizing Wolfspeed SiC MOSFETs combined with low cost silicon diodes to achieve peak efficiency above 98.5% which is suitable for 80+ titanium standard. Current trends lean toward the use of the latest SiC MOSFETs in new low inductance packaging to design a PFC system. When combined with a DC/DC circuit the system can achieve system-level efficiency suitable for 80+ titanium standard. Attendees will learn the tradeoffs of using different switches and will provide a review of a design which delivers a peak efficiency > 98.5% and THD < 5%. The design has higher power density than existing silicon 80+ platinum solutions and with higher efficiency all at equivalent EBOM cost.

If you’d like to learn how to enable server and telecom power supplies to reach 80+ titanium efficiency requirements with no additional cost or complexity, understand the benefits of low-inductance discrete SiC MOSFET packaging and Kelvin-contact, or explore the latest SiC MOSFETs with low conduction losses, switching losses and Qrr, enabling new, simplified power conversion topologies, check out the upcoming the upcoming webinar.

Register here to learn more.

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