Arthur G. Birchenough and David S. Hervol

QinetiQ North America Operations LLC, Cleveland, Ohio

Brent G. Gardner

Glenn Research Center, Cleveland, Ohio

Test Results From a High Power Linear

Alternator Test Rig

NASA/TM—2010-216910

November 2010

AIAA–2010–6691
NASA STI Program . . . in Profi le

Since its founding, NASA has been dedicated to the 

advancement of aeronautics and space science. The 

NASA Scientifi c and Technical Information (STI) 

program plays a key part in helping NASA maintain 

this important role.

The NASA STI Program operates under the auspices 

of the Agency Chief Information Offi cer. It collects, 

organizes, provides for archiving, and disseminates 

NASA’s STI. The NASA STI program provides access 

to the NASA Aeronautics and Space Database and 

its public interface, the NASA Technical Reports 

Server, thus providing one of the largest collections 

of aeronautical and space science STI in the world. 

Results are published in both non-NASA channels 

and by NASA in the NASA STI Report Series, which 

includes the following report types:

• TECHNICAL PUBLICATION. Reports of 

completed research or a major signifi cant phase 

of research that present the results of NASA 

programs and include extensive data or theoretical 

analysis. Includes compilations of signifi cant 

scientifi c and technical data and information 

deemed to be of continuing reference value. 

NASA counterpart of peer-reviewed formal 

professional papers but has less stringent 

limitations on manuscript length and extent of 

graphic presentations.

• TECHNICAL MEMORANDUM. Scientifi c 

and technical fi ndings that are preliminary or 

of specialized interest, e.g., quick release 

reports, working papers, and bibliographies that 

contain minimal annotation. Does not contain 

extensive analysis.

• CONTRACTOR REPORT. Scientifi c and 

technical fi ndings by NASA-sponsored 

contractors and grantees.

• CONFERENCE PUBLICATION. Collected 

papers from scientifi c and technical 

conferences, symposia, seminars, or other 

meetings sponsored or cosponsored by NASA.

• SPECIAL PUBLICATION. Scientifi c, 

technical, or historical information from 

NASA programs, projects, and missions, often 

concerned with subjects having substantial 

public interest.

• TECHNICAL TRANSLATION. Englishlanguage translations of foreign scientifi c and 

technical material pertinent to NASA’s mission.

Specialized services also include creating custom 

thesauri, building customized databases, organizing 

and publishing research results.

For more information about the NASA STI 

program, see the following:

• Access the NASA STI program home page at 

http://www.sti.nasa.gov

• E-mail your question via the Internet to help@

sti.nasa.gov

• Fax your question to the NASA STI Help Desk 

at 443–757–5803

• Telephone the NASA STI Help Desk at

 443–757–5802

• Write to:

 NASA Center for AeroSpace Information (CASI)

 7115 Standard Drive

 Hanover, MD 21076–1320
Arthur G. Birchenough and David S. Hervol

QinetiQ North America Operations LLC, Cleveland, Ohio

Brent G. Gardner

Glenn Research Center, Cleveland, Ohio

Test Results From a High Power Linear

Alternator Test Rig

NASA/TM—2010-216910

November 2010

AIAA–2010–6691

National Aeronautics and

Space Administration

Glenn Research Center

Cleveland, Ohio 44135

Prepared for the

8th International Energy Conversion Engineering Conference (IECEC)

sponsored by the American Institute of Aeronautics and Astronautics

Nashville, Tennessee, July 25–28, 2010
Acknowledgments

The work in this paper was performed for the Exploration Technology Development Program and the Fission Surface Power 

Project. The authors would like to thank Wayne Gerber (BAE Systems), for his assistance with testing.

Available from

NASA Center for Aerospace Information

7115 Standard Drive

Hanover, MD 21076–1320

National Technical Information Service

5301 Shawnee Road

Alexandria, VA 22312

Available electronically at http://gltrs.grc.nasa.gov

Level of Review: This material has been technically reviewed by technical management. 
NASA/TM—2010-216910 1 

Test Results From a High Power Linear Alternator Test Rig 

Arthur G. Birchenough and David S. Hervol 

QinetiQ North America Operations LLC 

Cleveland, Ohio 44135 

Brent G. Gardner 

National Aeronautics and Space Administration 

Glenn Research Center 

Cleveland, Ohio 44135 

Abstract 

Stirling cycle power conversion is an enabling technology that provides high thermodynamic efficiency but also 

presents unique challenges with regard to electrical power generation, management, and distribution. The High 

Power Linear Alternator Test Rig (HPLATR) located at the NASA Glenn Research Center (GRC) in Cleveland, 

Ohio is a demonstration test bed that simulates electrical power generation from a Stirling engine driven alternator. 

It implements the high power electronics necessary to provide a well regulated DC user load bus. These power 

electronics use a novel design solution that includes active rectification and power factor control, active ripple 

suppression, along with a unique building block approach that permits the use of high voltage or high current 

alternator designs. This report describes the HPLATR, the test program, and the operational results. 

Nomenclature 

MPa megapascal 

Hz hertz 

VAC volts AC 

VDC volts DC 

kWe kilowatts (electric) 

I. Introduction 

As a step toward the development of a Stirling power convertor for use in a lunar Fission Surface Power (FSP) 

system, a pair of commercially available pressure wave generators was pneumatically connected with a pair of 

pressure wave alternators to create a High Power Linear Alternator Test Rig (HPLATR). The HPLATR is intended 

to simulate the coupling between the displacer piston and the power piston/linear alternator in a free piston Stirling 

engine. It was used to map and verify high power Stirling linear alternator performance and to develop a power 

management and distribution (PMAD) system. 

II. High Power Linear Alternator Test Rig Description 

A. Stirling Simulator 

It was necessary to provide AC power to the PMAD that was analogous in character to a Stirling engine. The AC 

power level also had to be relevant to planned FSP power systems. Since there are no available Stirling engines 

available at that power level, a simulated system was fabricated. Two commercially available Pressure Wave 

Generators (PWGs) were procured from Clever Fellows Innovation Consortium (CFIC), of Troy, New York. Each 

PWG unit consists of two CFIC STAR linear motors that are mounted in a dual opposed configuration for balanced 

operation. The CFIC PWG was originally designed to provide pressure waves for acoustic pulse tube cryocoolers. 

The PWG has no wearing parts or lubrication needs, which means long-life and no scheduled maintenance. A 

second PWG unit was plumbed to the first PWR to create a common closed pneumatic space between them. One of 

the PWG units is powered with a variable frequency ac power supply power supply. This pair creates a pressure 

wave driving the second PWG which acts as a pair of linear alternators in an opposed configuration. The net effect is 

similar to the way a Stirling convertor displacer piston creates a pressure wave to drive its power piston. A 

photograph of the PWG units as configured in the HPLATR test facility is shown in Figure 1. The nominal 

operating conditions of the PWG are given in Table 1. 
NASA/TM—2010-216910 2 

Figure 1.—Compressor alternator pairs as installed. 

TABLE 1.—PWG NOMINAL OPERATING CONDITIONS 

Charge gas Helium 

Charge pressure 4.0 MPa 

Nominal operating frequency 90 Hz 

Mover amplitude 13 mm 

Nominal voltage 330 VAC 

Nominal motor input power 10 kWe 

B. Stirling PMAD 

A Stirling based power system has several unique characteristics compared to systems based on high speed 

turbo-alternators (Refs. 1 to 3) or DC sources such as solar cells or fuel cells. The power output of the source is 

single phase AC. Because the instantaneous power goes through zero twice every cycle some energy storage is 

required to supply continuous power to the loads. Also, the output frequency of the Stirling alternator is a relatively 

low frequency, on the order of 50 to 100 Hz, so the use of line frequency power transformers to boost the voltage for 

long distance power transmission can be heavy. Therefore, the alternator output has a relatively high voltage. The 

power electronics must work directly from this voltage, but must also provide a lower DC bus voltage output. 

Additionally, the alternator has a relatively high internal inductance, which requires reactive compensation to deliver 

the power to the load, and the power must be drawn nearly in phase with the internal voltage to allow the Stirling 

engine to operate efficiently. 

Classically, power conditioning for a Stirling linear alternator used a passive system consisting of a full bridge 

rectifier and an output filter (Ref. 4). A parasitic load across the output bus provided voltage regulation and control 

of the Stirling engine stroke. However it could not perform the voltage regulation and stroke control functions 

independently from the other. Due to the high internal inductance of the linear alternator, a series tuning capacitor 

was used between the alternator and the rectifier. This compensated for the inductive impedance or else the 

inductive impedance was too great to extract much useful power out of the alternator. By adjusting the capacitor to 

be in resonance with the inductance, the output power was reasonably sinusoidal and in phase with the alternator 

motion. Both conditions were necessary for optimum operation of the Stirling engine. Increasing the alternator 

inductance and the impedance of the series capacitor improved how sinusoidal the waveform shape was, improving 

the Stirling engine operation. The drawback with this approach was that the capacitor became quite large, and the 

power losses in the inductor and capacitor decreased the overall efficiency. 

Using an active rectifier with active Power Factor Correction (PFC) eliminates the large tuning capacitor while 

maintaining optimum power factor on the alternator, and has low current harmonics with minimum distortion. 

Additionally, the regulation of the output bus voltage can be performed independently of the control of the Stirling 

engine stroke. 
NASA/TM—2010-216910 3 

Figure 2.—HPLATR functional schematic. 

The resulting linear alternator power conditioning system consists of three major elements. The functions of 

these elements are to rectify and filter the power output, provide constant engine loading, electrically isolate the 

load, convert to the desired bus voltage, and regulate the output bus voltage. These elements are the AC input 

module, a DC-DC converter module and a parasitic load regulator. A functional schematic of the overall HPLATR 

Stirling PMAD is shown in Figure 2. 

The linear alternator of the Stirling engine produces a relatively low, 50 to 100 Hz, single phase AC output. The 

first element of the power conditioning system, the AC input module, is an active rectifier which performs the power 

factor control (PFC) required to absorb the input power at the correct phase angle. The circuit, shown in Figure 3, 

consists of a full bridge converter using PWM controlled FETs to modulate the input current. The operation is 

similar to a full bridge circuit used as a DC-AC inverter, but operating in a manner such that the power flow is from 

the AC input to the DC output. The module essentially generates an AC voltage at its input, where the alternator is 

connected, and the input current is consumed as a result of the difference between the alternator voltage and the 

voltage generated by the inverter. The control circuits act to consume current in phase with the voltage, and the input 

power to the inverter is converted to a DC voltage at the output of the AC input module. A capacitor and inductor 

are placed on the AC input to filter out the high frequency (50 kHz) modulation frequency. This minimizes the EMI 

induced in the AC power line. 

The PFC circuit output is a DC voltage, but it is higher than desired for a user bus voltage, and also has a ripple 

component as a result of the single phase AC power input. The second element of the power conversion system is a 

DC-DC converter to reduce the PFC output voltage to the desired user bus voltage, and attenuate the voltage ripple. 

This stage is also required to provide isolation between the alternator bus and the user bus so that system grounding 

can be controlled independently between the power source and the user load bus. The circuit, shown in Figure 4, 

uses a full bridge inverter transformer coupled to a full bridge output rectifier. The inverter bridge uses high 

frequency conversion to minimize mass. This control method allows the frequency convertor to operate at a nearly 

constant duty cycle (9010 percent) which allows close control of the rectifier reverse voltage transients. 

The third element required is a parasitic load controller that is used to absorb the excess energy from the Stirling 

alternator that is not required by the user loads. By dissipating the excess energy the parasitic load controller 

regulates the bus voltage, and indirectly, the voltages within the AC input and the DC-DC converter stages. The 

circuit parasitic load controller, shown in Figure 5, uses PWM control of FET switches to modulate the power 

dissipated by the resistors. 

Current 

Compensation PFC Controller Power Stage

DC-DC 

Conversion

PLR

Power 

Stage

PLR

Voltage 

Bus

Voltage 

Sense

Current 

Feedback

Current 

Feedback

Voltage 

Sense

AC Input Module

DC-DC Convertor 

Module

Parasitic Load 

Regulator

Stirling 

Alternator

High-pass Filter
NASA/TM—2010-216910 4 

Figure 3.—AC input module schematic (Ref. 1). 

Figure 4.—DC-DC convertor schematic. 

Figure 5.—Parasitic load controller schematic. 

V

Linear Alternator

FET1

FET2 FET4

Ralt Lalt FET3

CDC

A

B

VAB

AC Input Module

VDC

Phase Shift

Modulator

High Pass

Filter

DC Bus

DC 

from 

Input 

Module

FET1

FET2 FET4

FET3

Full Bridge Inverter Transformer Full Bridge Output Rectifier

PWM

Modulator

Proportional 

Controller +

-

Vref

DC Bus

FET1 FET2 FET3 FET4
NASA/TM—2010-216910 5 

Figure 6.—Parallel connected power sage/DC-link for higher current handling capability. 

Figure 7.—Series connected power stage/DC-link for higher voltage handling capability. 

C. Series/Parallel Module Connections 

The AC input modules are always paired with one DC-DC converter module, and the DC-DC converter modules 

always have their outputs connected in parallel. Since the DC-DC converter modules provide isolation, the AC input 

modules may be connected in parallel to increase the current capability, as shown in Figure 6, or in series to increase 

their voltage capability as shown in Figure 7. The AC input modules always operate with independent controls, 

sensing the module input voltage and current, and the DC-DC converter modules also operate with independent 

controls, sensing their output current. The only common controls on any of these modules are the power commands 

to the AC modules used to control the engine stroke. 

Since the control systems for these series and parallel modules are independent, the connections are simple and 

robust. Alternatively, individual current control could be used, but some balancing network would have to be 

employed, with its additional control loop stability concerns. By using a common control signal the single feedback 

path assures the switching will command the correct input current. An unbalance in the series or parallel connected 

stages will show up as a slightly different output power from each stage, but the unbalance is only a few percent 

even without any attempt to trim the circuits to balance them. Although differences in the modules result in some 

unbalance in the power they absorb, there is no interaction between modules, and therefore no control signal 

compensation required. 

D. Stirling and PMAD Control System 

The control strategies for the converter modules are a function of the use of the series and parallel connections. 

Each of the AC input modules, DC-DC converter modules, and the parasitic load controller has its own function, 

and the control functions are set up to allow these separate functions, and minimize interactions with the other 

modules. 

 

DC 

Convertor 

Module 1

120 VAC

120 

VAC 

ALT

120 VAC

200 VDC

200 VDC

DC 

Convertor 

Module 2

120 VDC

120 VDC

To 

Regulated 

DC Bus 

AC Input 

Module 1

AC Input 

Module 2

120 VAC

240 

VAC 

ALT

120 VAC

200 VDC

DC 

Convertor 

Module 2

200 VDC

DC 

Convertor 

Module 1

120 VDC

120 VDC

To 

Regulated 

DC Bus

AC Input 

Module 1

AC Input 

Module 2
NASA/TM—2010-216910 6 

The controls on the AC input modules perform two functions: The first is to consume current in phase with the 

alternator internal voltage source; the 2nd is to vary the amount of power it consumes to control the stroke of the 

linear alternator. The DC-DC converter controls are designed to convert the nominal 200 VDC input voltage to 

120 V, and to attenuate the ripple voltage on the input. The parasitic load controller is designed to shunt excess 

power to the parasitic load elements in order to regulate the bus voltage to 120 VDC as the power input from the 

Stirling engines and the user loads vary. 

Separating the control functions between AC input module, the DC-DC converter modules, and the PLR 

controller, allows parallel and series modules connections without changing the interaction between the modules. 

The AC input module outputs a nominal 200 V, with several percent ripple in the voltage due to the low frequency 

single phase input. But the AC input module does not regulate this voltage; it just pumps energy into its output filter 

in response to the power level command. A reference voltage, which will be nearly in phase with the internal 

alternator EMF is generated based on the alternator terminal voltage, with a compensation for the voltage drop 

across the internal inductance of the alternator. The power level command is developed from a measurement of the 

engine/alternator stroke, and the control loop increases the power command if the stroke exceeds its set point. The 

power level command is generated by a common controller, and must be isolated for each of the modules to 

maintain independence of the modules. 

Since the DC-DC converter module does not have a voltage regulation loop, it operates at an almost constant 

conversion ratio, but modulated 10 percent to attenuate the ripple voltage at its input. The ripple is attenuated by 

controlling to a constant output current, but the DC component of the current feedback signal is removed by a high 

pass filter and the primary ripple current at twice the input frequency is the only active component in the control 

loop. With this control scenario, the DC-DC converter does not have a voltage regulation or power set point or any 

other external command input; it merely pumps whatever power is available from the AC input module to the output 

bus, and removes most of the AC ripple. 

The voltage regulation is performed by the PLR controller stage connected in parallel with the power output bus. 

Since the DC-DC converter stage(s) are pumping current into the PLR controller stage, largely independent of the 

actual voltage at the bus, interactions are minimized. 

III. Testing 

The optimum Stirling engine operating frequency was determined by operating the engine at a constant drive 

motor voltage and then sweeping the drive frequency until a maximum alternator piston stroke was determined. For 

these tests the frequency was on the order of 90 Hz. Once this frequency was established, the amount of power 

produced by the linear alternator was varied by manually changing the drive motor voltage and commanding the 

desired current drawn by the AC power stage. 

A. DC Bus Voltage Control With Switched User Loads 

The first test, performed with the AC input modules in the parallel configuration, demonstrated the capability of 

the parasitic load to successfully regulate the DC user bus. The system was placed at a constant AC power output so 

that the corresponding total DC bus power was also constant. A series of five load combinations were then applied 

in increasing and decreasing fashion. The DC bus voltage and current were measured along with the user load 

current. The resulting DC bus and user load power was calculated. The timeline of the test showing user loads, DC 

bus power, current and voltage are shown in Figure 8. During the testing, the DC bus was deliberately “overloaded” 

by adding excess user load. This caused a DC bus voltage drop. The user load current increased in relative 

proportion to maintain a constant power level. These results are more clearly shown in Figure 9. The alternator 

voltage and stroke remained unaffected thus demonstrating the ability of the PMAD DC bus to provide protection to 

the linear alternator from adverse loading conditions. 

B. DC Bus Current With and Without Ripple DC-DC Link Ripple Suppression 

The next test examined the effectiveness of the DC-DC link high-pass filter current feedback in suppressing DC 

Bus current ripple. The HPLATR was operated at a constant power level to obtain time traces of DC link input 

voltage and DC bus current with the active ripple suppression operational (Fig. 10). The current feedback loop was 

then disabled and the same data was taken (Fig. 11). The difference in the magnitude in DC bus current traces 

between the two charts graphically illustrates the effectiveness of this method. 
NASA/TM—2010-216910 7 

Figure 8.—User load test. 

Figure 9.—User load current and voltage characteristics. 

0

40

80

120

160

200

0

200

400

600

800

1000

1200

1400

1600

1800

566 586 606 626 646 666 686

DC Voltage, DC Current x 10

Electrical Power(watts)

Test Sequence elapsed Time (seconds)

DC Bus

Power

User Load

Power

DC Bus

Voltage

User Load

Current x 10

0

4

8

12

16

0

20

40

60

80

100

120

140

160

180

0 400 800 1200 1600

Amps, Alternator Stroke (mm)

Volts

User Load (Watts)

DC Bus

Voltage

User

Load

Current

Linear

Alt.

Stroke

Linear

Alt.

Current

Overload 

Condition
NASA/TM—2010-216910 8 

Figure 10.—DC bus current with DC-DC link active suppression. 

Figure 11.—DC bus current without DC-DC link active suppression. 

0

1

2

3

4

5

100

150

200

250

300

0.000 0.005 0.010 0.015 0.020

Volts

Amps

Seconds

DC link

Input

Voltage

DC Bus

Current

0

1

2

3

4

5

100

150

200

250

300

0.000 0.005 0.010 0.015 0.020

Volts

Amps

Seconds

DC link

Input

Voltage

DC Bus

Current
NASA/TM—2010-216910 9 

C. Parallel and Series Module Configuration Tests 

The final series of tests demonstrated the ability to connect the power modules in parallel or series depending on 

whether current or voltage handling capability is to be optimized. One of the measures that determine how well this 

works is the ability for the power modules to handle the power loads equally, and how well the DC user bus voltage 

is regulated regardless of how they are connected. This was first done with the power modules hooked in parallel. 

The resulting power sharing between the modules and DC bus voltage versus the alternator output power is shown 

in Figure 12. DC bus regulation was maintained for all realistic alternator power output levels (greater than 50 W) 

with the DC modules showing good power sharing between them. 

The modules were then connected in series. The test was rerun at the same alternator output levels. Good DC bus 

regulation was maintained at all realistic alternator power output levels and the DC modules showing good power 

sharing between them. This is graphically shown in Figure 13. 

Figure 12.—Parallel connected power modules. 

Figure 13.—Series connected power modules. 

0

200

400

600

800

1000

0

20

40

60

80

100

120

140

0 500 1000 1500 2000

Volts

Watts

AlternatorPower Output (watts)

DC Bus

Voltage

DC1 Power

DC2 Power

0

200

400

600

800

1000

0

20

40

60

80

100

120

140

0 500 1000 1500 2000

Volts

Watts

AlternatorPower Output (watts)

DC Bus

Voltage

DC1 Power

DC2 Power
NASA/TM—2010-216910 10 

IV. Conclusions 

The innovative use of independent controls to divide the functions of rectification, DC bus ripple suppression, 

and DC voltage control on a linear alternator representative of a Stirling engine was successfully demonstrated. 

The DC bus parasitic load control maintained correct voltage regulation throughout a wide range of user loading 

conditions. The only exception to this came from a deliberate bus overload. This overload did not affect the total 

electrical load and AC voltage on the linear alternator due to the operation of the AC input module. 

The DC-DC link current feedback loop using a high pass filter provided excellent DC bus current ripple 

suppression and provided electrical isolation from the linear alternator. Finally, by demonstrating successful power 

sharing of the AC input modules and corresponding DC-DC this method of PMAD control allows flexibility to 

configure the system for either high current or high voltage alternator designs. 

References 

1. Birchenough, A., and Hervol, D., “Test Results from a Simulated High-Voltage Lunar Power Transmission 

Line,” NASA/TM—2008-215164, 2008. 

2. Birchenough, A., and Hervol, D., “Operational Results from a High Power Alternator Test Bed,” NASA/TM—

2007-214708, 2007. 

3. Hervol, D., Mason, L., Birchenough, A., and Pinero, L., “Experimental Investigations from the Operation of a 

2 kW Brayton Power Conversion Unit and a Xenon Ion Thruster,” NASA/TM—2004-212960, 2004. 

4. Santiago W., and Birchenough, A., “Single Phase Passive Rectification Versus Active Rectification Applied to 

High Power Stirling Engines,” NASA/TM—2006-214045, 2006. 
REPORT DOCUMENTATION PAGE Form Approved 

OMB No. 0704-0188 

The public reporting burden for this collection of information is estimated to average 1 hour per response, including the time for reviewing instructions, searching existing data sources, gathering and maintaining the 

data needed, and completing and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this collection of information, including suggestions for reducing this 

burden, to Department of Defense, Washington Headquarters Services, Directorate for Information Operations and Reports (0704-0188), 1215 Jefferson Davis Highway, Suite 1204, Arlington, VA 22202-4302. 

Respondents should be aware that notwithstanding any other provision of law, no person shall be subject to any penalty for failing to comply with a collection of information if it does not display a currently valid OMB 

control number. 

PLEASE DO NOT RETURN YOUR FORM TO THE ABOVE ADDRESS. 

1. REPORT DATE (DD-MM-YYYY)

01-11-2010 

2. REPORT TYPE

Technical Memorandum 

3. DATES COVERED (From - To)

4. TITLE AND SUBTITLE

Test Results From a High Power Linear Alternator Test Rig 

5a. CONTRACT NUMBER

5b. GRANT NUMBER

5c. PROGRAM ELEMENT NUMBER

6. AUTHOR(S)

Birchenough, Arthur, G.; Hervol, David, S.; Gardner, Brent, G. 

5d. PROJECT NUMBER

5e. TASK NUMBER

5f. WORK UNIT NUMBER

WBS 463169.04.03.04.01.04 

7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

John H. Glenn Research Center at Lewis Field 

Cleveland, Ohio 44135-3191 

8. PERFORMING ORGANIZATION

 REPORT NUMBER

E-17388 

9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES)

National Aeronautics and Space Administration 

Washington, DC 20546-0001 

10. SPONSORING/MONITOR'S

 ACRONYM(S)

NASA 

11. SPONSORING/MONITORING

 REPORT NUMBER

NASA/TM-2010-216910 

12. DISTRIBUTION/AVAILABILITY STATEMENT

Unclassified-Unlimited 

Subject Category: 20 

Available electronically at http://gltrs.grc.nasa.gov 

This publication is available from the NASA Center for AeroSpace Information, 443-757-5802

13. SUPPLEMENTARY NOTES

14. ABSTRACT

Stirling cycle power conversion is an enabling technology that provides high thermodynamic efficiency but also presents unique challenges 

with regard to electrical power generation, management, and distribution. The High Power Linear Alternator Test Rig (HPLATR) located at 

the NASA Glenn Research Center (GRC) in Cleveland, Ohio is a demonstration test bed that simulates electrical power generation from a 

Stirling engine driven alternator. It implements the high power electronics necessary to provide a well regulated DC user load bus. These 

power electronics use a novel design solution that includes active rectification and power factor control, active ripple suppression, along 

with a unique building block approach that permits the use of high voltage or high current alternator designs. This report describes the 

HPLATR, the test program, and the operational results.

15. SUBJECT TERMS

Electric power; Rectification; Voltage convertors 

16. SECURITY CLASSIFICATION OF: 17. LIMITATION OF

 ABSTRACT

UU 

18. NUMBER

 OF 

 PAGES

16 

19a. NAME OF RESPONSIBLE PERSON

STI Help Desk (email:help@sti.nasa.gov) 

a. REPORT

U 

b. ABSTRACT

U 

c. THIS 

PAGE

U 

19b. TELEPHONE NUMBER (include area code)

443-757-5802 

Standard Form 298 (Rev. 8-98)

Prescribed by ANSI Std. Z39-18