Challenges and Solutions in Measuring Computer Power Supply Efficiency for 80 PLUS® Certification

Abstract

This paper discusses the techniques, challenges, and results of measuring computer power supply (CPS) efficiency, power factor (PF), and input harmonic currents for the 80 PLUS® program since its beginning in 2002. To date, over 750 power supplies have been tested with many certified for the 80 PLUS® program. In spite of the large number of power supplies tested and years of testing, there is uncertainty within the computer power supply industry about the correct method for measuring efficiency, power factor, and harmonics. Moreover, in order to improve efficiency at light loading, manufacturers are adopting a duty-cycle control approach to power factor correction that raises even more questions on the proper measurement techniques. This paper presents detailed results of years of computer power supply testing, provides a detailed technical analysis on measurement accuracy with background on why specific measurement techniques were adopted, and looks to the future on upcoming technical difficulties and offers solutions for overcoming these difficulties.

Endpoint Use Efficiency Comparison for AC and DC Power Distribution in Commercial Buildings

“…The lower efficiency at partial load is mainly due to economic factors, including the use of low-quality electronic components [19] and a tendency to prioritize factors other than efficiency, such as size and cost, when manufacturing or procuring power supplies. Some organizations and programs promote higher efficiency, such as Energy Star [20,21], Climate Savers [22,23], DOE level VI efficiency standards for wall adapters [24,25], and 80 PLUS [26,27]. The latter, for instance, certifies power supplies that achieve at least 80% efficiency in energy conversion at 20%, 50%, and 100% of rated load [28] and also offers higher tiers of certification (bronze, silver, gold, etc.)…”

Transformer Isolated SCALDO Based High Current DC Power Supply

“…Maintaining a higher efficiency is one of the key challenges faced by the power supply designers.The 80+ group of power supply manufacturers are well known for maintaining the efficiency of their computer power supplies above 80% at all load conditions. Figure 2 depicts the evolution of efficiency in the 80+ group power supplies [2].…”

On Evaluation of Power Electronic Devices’ Efficiency for Nonsinusoidal Voltage Supply and Different Operating Powers

“…Efficiencies, in [20]- [23], PVIs' efficiencies are represented 97 as averaged operating values for the assumed or calculated 98 changes in annual distribution of input solar power, dis-99 cussing their applicability for different geographic locations 100 and climates. In case of SMPS, for which similar efficiency 101 certification is given by, e.g., "80 Plus" labels [24], the eval-102 uation of efficiencies is discussed in [25]- [27] impedance values for different operating powers/modes, allow-113 ing to assess exchanges of powers at fundamental system 114 frequency and nonfundamental (i.e., harmonic) frequencies. 115 Reference [9] was made to the "total" device efficiency from 116 the input to the output of the device, and to the "fundamental 117 power" device efficiency.…”