APPENDIX 5D. MAX-TECH

TABLE OF CONTENTS

5D.1 OVERVIEW ................................................................................................................. 5D-1

5D.2 METHODOLOGY ....................................................................................................... 5D-1

5D.3 ACTIVE RECTIFICATION ......................................................................................... 5D-1

5D.3.1 Efficiency .................................................................................................... 5D-2

5D.3.2 Price ............................................................................................................ 5D-2

5D.4 IMPROVED COMPONENTS...................................................................................... 5D-2

5D.4.1 Efficiency .................................................................................................... 5D-3

5D.4.2 Price ............................................................................................................ 5D-3

5D.5 CONCLUSION ............................................................................................................. 5D-4

LIST OF TABLES

Table 5D.1 Incremental Price Increase Per Ballast To Go From Passive to Active

Rectification ................................................................................................ 5D-2 Table 5D.2 Component Price Mar kups and Price Composition............................................... 5D-4

5D-iAPPENDIX 5D. MAX-TECH

5D.1 OVERVIEW

When the U.S. Department of Energy (DOE) pr oposes to adopt or to decline to adopt an amended or new standard for a type (or class) of covered product, as pa rt of the rulemaking process, DOE must ‘‘determine the maximum improvement in energy efficiency or maximum reduction in energy use that is technologically feasible’’ for the product. (42 U.S.C. 6295(p)(1)) In the technology assessment, DOE identifie d various technology options employed in commercially available ballasts to improve efficiency. DOE then applied the four screening criteria to determine which of these options DOE would consider in the engineering analysis. In this chapter DOE presents two technology options that are not currently used in commercially available ballasts. Although these two options have not yet met the screening criteria of technological feasibility, DOE believes they may be a viable option for improving the efficiency of ballasts beyond that which exists in the market today. In this appendix, DOE discusses these options and presents incremental efficiency and price increases associated with each one. DOE requests comment on the maximum technologically f easible ballast efficiency and its associated

costs.

5D.2 METHODOLOGY

DOE investigated multiple sources to identify the two possible technology options presented in this appendix. DOE obtained info rmation from manufacturer interviews, subject matter experts, scholarly article s, U.S. patents, and manufactur er marketing information. DOE also considered efficiency improvements used in comparable products, such as power supplies. The following sections discuss active rectifi cation and certain improved components that DOE identified to improve a ballast’s efficiency beyond that of the most efficient ballasts currently

available.

5D.3 ACTIVE RECTIFICATION

In the engineering analysis, the most efficient ballasts DOE identified were electronic ballasts. As described in the technology a ssessment (preliminary TSD chapter 3), the second stage of an electronic ballast is the input rectifier, which convert s AC to DC current. Through its research, DOE learned that commercially availa ble ballasts use a process known as passive rectification to complete this step. A passive rect ification circuit typically consists of four diodes to rectify the AC waveform. Passive rectification is currently used in commercially available ballasts because it is simple to design, contains few parts, is very reliable, and is cheap to

manufacture. 1

With technological advancem ents in electronics in th e past few decades and new developments in controls, meta l-oxide-semiconductor field-effect transistors (MOSFETs) have become a popular component of power electronics . MOSFETs have much lower electrical losses compared to diodes. Active rectification uses th ese MOSFETs in place of diodes to convert AC to DC current. Because MOSFETs operate in a slightly different manner than diodes, an

5D-1integrated circuit is necessary to switch the MOSFETs on and off as required. Even though this requires additional circuitry, the use of active rectification still results in an overall increase in efficiency because the electrical losses of the MOSFETs are much smaller than that of the

diodes.

5D.3.1 Efficiency

In the technology assessment (preliminar y TSD chapter 3), DOE classified the rectification stage of an electronic ballast as having a relatively low impact on overall ballast efficiency. However, when considering impr ovements required to move above 92 percent efficiency, even small improveme nts matter. After conversations with subject matter experts and parts suppliers, DOE believes that going from passive to active rectification could result in a one percentage point increase in overall efficiency.

5D.3.2 Price

To determine the incremental increase in pric e to go from passive to active rectification, DOE interviewed part suppliers and reviewed the bill of material from its teardown analysis to identify prices of individual components. DOE calculated the average cost of a passive rectification circuit – assuming the main component s of the circuit were four diodes. DOE then calculated a minimum, average, and maximum cost of an active rectification circuit – assuming the circuit was composed of four MOSFETs and a chip instead of four diodes. The incremental prices specified in the table below represent th e minimum, average, and maximum cost of an active rectification circuit minus the average cost of a passive rectification circuit.

Table 5D.1 Incremental Price Increase Per Ballast To Go From Passive to Active

Rectification

Min
$ Average
$ Max
$
Manufacturer Selling Price 0.02 1.69 4.62

5D.4 IMPROVED COMPONENTS

As described in the technology assessment (preliminary TSD chapter 3), improving the quality of the components in a ballast can increase efficiency. In particular, diodes, transistors, transformers, and capacitors are the main components that impact efficiency. Using the most efficient 2-lamp, 4-foot 32 watt medium bipin ballast as a point of reference, DOE used manufacturer datasheets to identify alternative co mponents with lower electrical losses to be used in a more efficient ballast design. If mo re than one alternative existed, DOE chose the component that demonstrated the lowest electri cal losses and therefore had the greatest potential to impact overall efficiency. DOE considered imp rovements for all components of the ballast, regardless of the stage in which they were used.

5D-25D.4.1 Efficiency

Based on conversations with subject matte r experts and members of the ballast and electronics community, DOE believes improving th e efficiency (reducing electrical losses) of components which are currently included in the most efficient commercia lly available ballast could result in a 1 to 2 percentage point increase in efficiency. In this section, DOE discusses the characteristics of the alternative compone nts it identified as possible substitutes.

DOE discovered that many types of diodes are employed in fluorescent ballasts, including: traditional silicon p-n junction diodes; avalanche diodes; Zener diodes; transient voltage suppression diodes; switc hing diodes; Schottky diodes; and DIAC trigger diodes. For this analysis, DOE proposes to replace traditional silicon p-n junction diodes with silicon carbide Schottky diodes. Although the substitute is significantly more expensive than the diode currently in use in commercially available ballasts, it offers the greatest improvement in efficiency. Economic impacts are considered in the life-cycle cost and national impact analyses. For the remaining diode types, DOE did not identify more efficient alternatives.

For transformers, DOE considered the use of improved core materials to reduce core losses. A higher quality core material can decrease the losses attributable to hysteresis and eddy currents. DOE assumed transformers currently used in fluorescent lamp ballasts employ an inexpensive, low-grade steel. DOE believes that M-43 non-oriented steel best approximates the low-grade, non-oriented steel in commercially av ailable ballasts. Thus, to improve efficiency, DOE proposes using M-2 a grain-oriented steel instead of lo w-grade, non-oriented steel in the

core of the transformers.

For transistors and capacitors, DOE had limite d success in identifying more efficient replacements. As indicated in Table 5D.2, DOE found altern ative MOSFETs with reduced electrical losses, but did not lo cate more efficient bipolar tran sistors. Thus, DOE only proposes to replace existing MOSFETS with a more effici ent substitute. For electrolytic capacitors, DOE identified several more efficient components as po tential replacements for low-voltage (less than 100 volts) electrolytic capacitors, but did not find more efficient alternatives for high-voltage (greater than 100 volts) electrolytic capacitors or for metalized polypropylene film capacitors. Consequently, DOE only proposes to replace exis ting low-voltage electrolytic capacitors with

more efficient substitutes.

5D.4.2 Price

To determine the incremental price for replacing the components found in the most efficient commercially available ballast with the most effici ent components available, DOE compared online pricing from electronics distribut ors. DOE divided the price of most efficient component on the market by the price for the component currently used in the ballast to determine a price markup. DOE then applied the markup to the component prices identified in the teardown analysis of the most efficient commercially available ballast. The resulting price is an estimate of the cost of the most efficient component on the market. By executing this process

a The American Iron and Steel Institute designates the grad e of electrical steel with an ‘M’ followed by a number.

Smaller numbers indicate electrical steel with smaller losses.

5D-3for all of the components for which DOE identified a more efficient replacement, DOE was able to calculate the price of a ballast that uses the most efficient components available. b DOE estimated the MSP of this theoretical ballast to be 56 percent more expensive than the most efficient commercially available ballast.

Table 5D.2 Component Price Markups and Price Composition

Component Type % of MSP for the most efficient commercially available ballast Markup % of MSP for the theoretical

max-tech ballast Diode, silicon p-n junction type 2% 29.1 31%

MOSFET 5% 1.45 4% Electrolytic capac itor <1% 1.4 <1% Transformer, core c 14% 1.99 17%

5D.5 CONCLUSION

As described in the above sections, DOE identified two technology options that may improve ballast efficiency beyond that of commercially available ba llasts. Both of these options are employed in power supplies and other comp arable power products. Although neither option is present in commercially available ballasts, DOE believes it is likely that they are technologically feasible because they are em ployed in similar products. As such, DOE has included them in this appendix to request comme nt on the likelihood that these two options will improve the overall efficiency of existing ballasts. DOE also requests comment its estimates of the incremental efficiency improvements and price increases associated with each option.

b For example, if the price for the component currently used in the ballast was $0.50 using an online distributor’s pricing and the most efficient replacement was $0.75, the markup would be 1.5. The markup of 1.5 would then be applied to the estimated price in the teardown bill of materials (for example, $0.30) to estimate a max-tech component cost of $0.45.

c For transformers, DOE assumed 60 percent of the manufactur er production cost is attributable to the core and 40 percent to the windings. These estimates were based on a bill of material acquired from a teardown analysis of a small electric motor. The small electric motor in this analysis had copper wire windings and non-oriented steel

cores.
5D-4REFERENCES

1 Santiago, Walter and Arthur G. Birchenough. Single Phase Rectification Versus Active Rectification Applied to High Power Stirling Engines . Third International Energy Conversion Engineering Conference; 2005 Aug 15 – 18; San Fr ancisco, California. Maryland: NASA Center for Aerospace Information; 2006. p. 1-12.

5D-5