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 Markups and Price Composition............................................... 5D-4
 

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APPENDIX 5D. MAX-TECH
 

5D.1 OVERVIEW
 

When the U.S. Department of Energy (DOE) proposes to adopt or to decline to adopt an 

amended or new standard for a type (or class) of covered product, as part 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 identified 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 feasible 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 information from manufacturer interviews, subject 

matter experts, scholarly articles, U.S. patents, and manufacturer marketing information. DOE 

also considered efficiency improvements used in comparable products, such as power supplies. 

The following sections discuss active rectification 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 assessment (preliminary TSD chapter 3), the second 

stage of an electronic ballast is the input rectifier, which converts AC to DC current. Through its 

research, DOE learned that commercially available ballasts use a process known as passive 

rectification to complete this step. A passive rectification 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 advancements in electronics in the past few decades and new 

developments in controls, metal-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 these MOSFETs in place of diodes to convert AC 

to DC current. Because MOSFETs operate in a slightly different manner than diodes, an 

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integrated 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 (preliminary 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 improvements required to move above 92 percent 

efficiency, even small improvements 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 price 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 components 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 the 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 components with lower electrical losses to be 

used in a more efficient ballast design. If more than one alternative existed, DOE chose the 

component that demonstrated the lowest electrical losses and therefore had the greatest potential 

to impact overall efficiency. DOE considered improvements for all components of the ballast, 

regardless of the stage in which they were used. 

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5D.4.1 Efficiency 

Based on conversations with subject matter experts and members of the ballast and 

electronics community, DOE believes improving the efficiency (reducing electrical losses) of 

components which are currently included in the most efficient commercially available ballast 

could result in a 1 to 2 percentage point increase in efficiency. In this section, DOE discusses the 

characteristics of the alternative components 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; switching 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 available ballasts. Thus, to improve efficiency, 

DOE proposes using M-2a

 grain-oriented steel instead of low-grade, non-oriented steel in the 

core of the transformers. 

For transistors and capacitors, DOE had limited success in identifying more efficient 

replacements. As indicated in Table 5D.2, DOE found alternative MOSFETs with reduced 

electrical losses, but did not locate more efficient bipolar transistors. Thus, DOE only proposes 

to replace existing MOSFETS with a more efficient substitute. For electrolytic capacitors, DOE 

identified several more efficient components as potential 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 existing 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 efficient components available, DOE 

compared online pricing from electronics distributors. 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 grade of electrical steel with an ‘M’ followed by a number. 

Smaller numbers indicate electrical steel with smaller losses. 

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for 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 capacitor <1% 1.4 <1% 

Transformer, corec

 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 ballasts. Both of these options 

are employed in power supplies and other comparable power products. Although neither option 

is present in commercially available ballasts, DOE believes it is likely that they are 

technologically feasible because they are employed in similar products. As such, DOE has 

included them in this appendix to request comment 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 manufacturer 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. 

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REFERENCES 

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 Francisco, California. Maryland: NASA Center 

for Aerospace Information; 2006. p. 1-12. 

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