Unclassified PresentationUnclassified Presentation

Julio C. G. Pimentel

IEEE

Dept. of Computer

and Electrical Engineering

Ste. Foy, Quebec, Canada

Yosef Gavriel Tirat-GefenIEEE, AIAA

Castel Research Inc.www.castelresearch.com

Fairfax, VAe-mail:

yosefgavriel@computer.org& George Mason University

Fairfax, VA

Validation of Mission Critical Power and Control Systems

for Lunar Settlement

OverviewOverview MotivationMotivation Related WorkRelated Work Mission Critical SystemsMission Critical Systems Power Systems for Lunar SettlementPower Systems for Lunar Settlement Control Systems ValidationControl Systems Validation Solar Array Based Power System Solar Array Based Power System

ExampleExample ConclusionConclusion

MotivationMotivation Major systems to be used in the Lunar Major systems to be used in the Lunar

settlement:settlement: Power GenerationPower Generation Life SupportLife Support TransportTransport

Systems are subject to malfunction, faults, Systems are subject to malfunction, faults, etc…etc…

Need to Validate the systems forNeed to Validate the systems for Design errorsDesign errors Degraded operation under faultDegraded operation under fault Sensitivity to design parametersSensitivity to design parameters

Validation cost should be affordableValidation cost should be affordable

Related WorkRelated Work Jiang, Z., Liu, S. and Dougal, R. A., “Design and Testing of Spacecraft Power Systems Jiang, Z., Liu, S. and Dougal, R. A., “Design and Testing of Spacecraft Power Systems

Using VTB,” IEEE Transactions on Aerospace and Electronic Systems, Vol. 39, No. 3, Using VTB,” IEEE Transactions on Aerospace and Electronic Systems, Vol. 39, No. 3, July 2003, pp. 976-989.July 2003, pp. 976-989.

Cho, B. H., and Lee, F. C. Y. “Modeling and analysis of spacecraft power systems,” Cho, B. H., and Lee, F. C. Y. “Modeling and analysis of spacecraft power systems,” IEEE Transactions on Power Electronics, Vol. 3, No. 1, Jan. 1988, pp. 44–54.IEEE Transactions on Power Electronics, Vol. 3, No. 1, Jan. 1988, pp. 44–54.

Colombo, G., Grasselli, U., Deluca, A., and Spizzichino, A., “Satellite power system Colombo, G., Grasselli, U., Deluca, A., and Spizzichino, A., “Satellite power system simulation,” Acta Astronautica, Vol. 40, No. 1, 1997, pp. 41–49.simulation,” Acta Astronautica, Vol. 40, No. 1, 1997, pp. 41–49.

Rosero, J. A., Ortega, J. A., Aldabas, E. Romeral, L., “Moving Twords a More Electric Rosero, J. A., Ortega, J. A., Aldabas, E. Romeral, L., “Moving Twords a More Electric Aircraft,” IEEE A&E Systems Magazine, March 2007, pp. 3-9.Aircraft,” IEEE A&E Systems Magazine, March 2007, pp. 3-9.

Ganig6s, A., Carrasco, J. A., Blanes, J. M. and Sanchis, E., “Modeling the Sequential Ganig6s, A., Carrasco, J. A., Blanes, J. M. and Sanchis, E., “Modeling the Sequential Switching Shunt Series Regulator,” IEEE Power Electronics Letters, Vol. 3, No. 1, Switching Shunt Series Regulator,” IEEE Power Electronics Letters, Vol. 3, No. 1, March 2005, pp. 7-13.March 2005, pp. 7-13.

Patel, M.R., Spacecraft Power Systems, CRC Press, 2004.Patel, M.R., Spacecraft Power Systems, CRC Press, 2004. Billerbeck, W., and Lewis, G., Jr., “Spacecraft power system studies using Pspice,” Billerbeck, W., and Lewis, G., Jr., “Spacecraft power system studies using Pspice,”

36th Intersociety Energy Conversion Engineering Conference, Vol. 1, 2001, 1–18.36th Intersociety Energy Conversion Engineering Conference, Vol. 1, 2001, 1–18. Ganig6s, A., Carrasco, J. A., Rubiato, J., Avila, E. and Blanes, J. M., “System model of Ganig6s, A., Carrasco, J. A., Rubiato, J., Avila, E. and Blanes, J. M., “System model of

the sequential switching shunt series regulator for spacecraft regulated high power the sequential switching shunt series regulator for spacecraft regulated high power busses,” 351h Annual IEEE Power Electronics Specialists Conference, Aachen, busses,” 351h Annual IEEE Power Electronics Specialists Conference, Aachen, Germany, 2004, pp. 2645-2650.Germany, 2004, pp. 2645-2650.

Pimentel, J. C. G., “Hardware Emulation for Real-Time Power System Simulation,” Pimentel, J. C. G., “Hardware Emulation for Real-Time Power System Simulation,” IEEE International Symposium on Industrial Electronics - ISIE’2006, July 9-12, IEEE International Symposium on Industrial Electronics - ISIE’2006, July 9-12, Montreal, QC, Canada, 2006, pp. 1560-1565.Montreal, QC, Canada, 2006, pp. 1560-1565.

13Spice Simulator, University of California at Berkeley, 13Spice Simulator, University of California at Berkeley, http://bwrc.eecs.berkeley.edu/Classes/IcBook/SPICE/, 2002.http://bwrc.eecs.berkeley.edu/Classes/IcBook/SPICE/, 2002.

XILINX ISE, FPGA Development Tool, Software Package, Ver. 8.1i, Xilinx Inc., San XILINX ISE, FPGA Development Tool, Software Package, Ver. 8.1i, Xilinx Inc., San Jose, CA, 2006.Jose, CA, 2006.

Matlab/Simulink, Flow Graph Simulation Tool, Software Package, Ver. 7.0.4, Matlab/Simulink, Flow Graph Simulation Tool, Software Package, Ver. 7.0.4, Mathworks Inc., Natick, MA, 2004.Mathworks Inc., Natick, MA, 2004.

Modelsim, HDL Simulation Tool, Software Package, Ver. 6.1, Mentor Graphics Inc., Modelsim, HDL Simulation Tool, Software Package, Ver. 6.1, Mentor Graphics Inc., Winsonville, OR, 2005.Winsonville, OR, 2005.

Easy5, Multi-Discipline Simulation Tool, MSC Software Corp., Easy5, Multi-Discipline Simulation Tool, MSC Software Corp., http://www.mscsoftware.com/, Santa Ana, CA, 2007http://www.mscsoftware.com/, Santa Ana, CA, 2007

Critical Systems in a Lunar Critical Systems in a Lunar SettlementSettlement

Power System

Life Support (e.g. O2 and H2O processing and generation)

Transport system (e.g. evacuation modules)

Distributed Control Systems (e.g. supervisory control)

Validation and Validation and VerificationVerification

SimulationSimulation Off-lineOff-line Real-timeReal-time Hardware in the loopHardware in the loop

Formal methodsFormal methods Design by assertionDesign by assertion May be coupled to simulation based May be coupled to simulation based

methodsmethods

SimulationSimulation(Validate only what we know about)(Validate only what we know about)

System Model (Implementation)

Environmental Parameters

System Model

(high-level/ behavioral)

Low-level Simulator

High-level Simulator

Compare

Report of Bugs / Design Errors

Simulation => more computationally efficient

Formal MethodFormal Method(automatically validate the whole (automatically validate the whole

design space)design space)System Model

(Implementation)

Environmental Parameters

System Assertions

Model Checker

(Theorem Proofing)

Report of Bugs / Design Errors

Formal Methods => Much less efficient what limits the size of the design it can handle

State of the ArtState of the Art

Simulation:Simulation: Widely usedWidely used Not able to detect/cover all possible faultsNot able to detect/cover all possible faults Time consuming (write/run many simulation Time consuming (write/run many simulation

cases)cases) Formal Methods:Formal Methods:

Starting to be used for digital hardware Starting to be used for digital hardware designdesign

Not fully understood for hybrid systemsNot fully understood for hybrid systems Combinatory explosionCombinatory explosion

Mixed ApproachMixed Approach

System Model (Implementation)

Environmental Parameters

System Assertions

Model Checker

(Theorem Proofing)

Report of Bugs / Design Errors

Scenario co-simulation

Real-Time SimulationReal-Time SimulationHardware in the LoopHardware in the Loop

EquipmentUnderTest

DigitalRealTime

Simulator

(processing)(Z-1)

AnaAna

Ana

Dig

Dig

SamplingZ-1

Z-1

Sampling

Power - How Critical?Power - How Critical? On Earth:On Earth:

During a power failure, close to 90% of the During a power failure, close to 90% of the economic/human activity will be affectedeconomic/human activity will be affected

It is possible to wait a few hours or days for It is possible to wait a few hours or days for recoverrecover

On the Moon/Mars:On the Moon/Mars: Close to 100% of all activities are interruptedClose to 100% of all activities are interrupted Communication may be disruptedCommunication may be disrupted Life support activity is interruptedLife support activity is interrupted Air supply may be depleted in a few hoursAir supply may be depleted in a few hours Settlers may dieSettlers may die

Roadmap for Power Roadmap for Power GenerationGeneration

SolarSolar Immediately availableImmediately available

NuclearNuclear Within 10 years of the start of the Within 10 years of the start of the

settlementsettlement Mineral basedMineral based

Not sureNot sure

Solar Based Power Solar Based Power SystemSystem

Solar Array 1

Solar Array 2

Solar Array n

LoadEnergyStorageSystem

Main BusRegulatorSystem

Power Distribution and Control Unit

Redundancy

HIL Real-Time SimulationHIL Real-Time SimulationGeneral ArchitectureGeneral Architecture

EquipmentUnderTest

DigitalRealTime

Simulator

(processing)(Z-1)

AnaAna

Ana

Dig

Dig

SamplingZ-1

Z-1

Sampling

High Level ArchitectureHigh Level Architecture

Linearsub-circuit

Control

VoltageCurrent

VoltageCurrent

VoltageCurrent

VoltageCurrent

VoltageCurrent

VoltageCurrent

Scheduler

Non linear sub-circuits

State Space(Ad, Bd, Cd, Dd)

Control Control

Non linearSub-circuit

Non linearSub-circuit

Non linearSub-circuit

Non linearSub-circuit

Non linearSub-circuit

Non linearSub-circuit

Control

Examples of ModulesExamples of Modules

Voltages

EOC

LogicalSignals

Sub

CircuitCurrents

Voltages

Currents

LogicalSignals

RSTCLKS_CLKF_CLKENSTCREG

Examples of ModulesExamples of Modules

RSTCLK

EOC1

EOC2

EOCnScheduler

EN

STC_l

STC_nl

REG_l

REG_nl

Programming FlowProgramming Flow SimPowerSystem

SimulinkLibrary

VHDLSystemLibrary

SimPowerSystemSimulink

GenVhdl

ValidateVHDLLibrary

User

Power SystemSpec

Non linearSub-circuit

LinearSub-circuit

C/C++ Or FPGAFPGA

Scheduler

Hardware Description Hardware Description LanguageLanguage

Component ModelingComponent Modelingentity DiscPIController isgeneric (NBits:natural:=8; NBitsRadix:natural:=8; NBitsCoef:natural:=8; PIType:natura :=0; NCycles:natural:=1; A1:natural:=1; A2:natural:=1; Init:natural:=0; UpperBound:integer:=1; LowerBound: integer:=0 ); port (CLK: in STD_LOGIC; RST: in STD_LOGIC; EN: in std_logic; STC: in std_logic; Reg_output: in std_logic; Verr: in std_logic_vector (NBits-1 downto 0); Vcont: out std_logic_vector (NBits-1 downto 0); EOC: out std_logic );

Modeling a Power SwitchModeling a Power Switch

ψ

sample!{VQ1=inp}[STC==1]

store!{out=Ib1}[Reg==1]

turnon!{Ib1=Ib1+Is1}[P2]

{Ib1=Icalc1}

Icalc1=f(Ron1,Lon1,Rs1,Cs1)

Rs1

Rs2

Cs1

Cs2D2

Q1

G1

+

-

A

Ib1

Ib2

Q1 switching sequence

Is1

Is2

Ia

Q1_on = VQ1>0 and G1=1D2_on = not(Q1_on) and …...

D S

Gate

D S

Gate

Cs1 Rs1

Cs1 Rs1

Ron Lon

Ib1 = f(Vds, Vf, Ron, Lon, Rs1, Cs1)

Vf

Is1 = f(Vds, Vf, Ron, Lon, Rs1, Cs1)

(a) Electrical Model (b) MOS Switch electrical equivalent (c) Power Switch EFSM Model

Mathematical ModelMathematical Model

( ) ( ) ( ) ( )ds f on ds on ds

dV t V t R I t L I t

dt

( ) (1/ )( )

( ) ( ) 1 ( / )ds on

ds f on on

I s RH s

V s V s s L R

1 2( ) ( ) ( 1))ds ds dsI n A V n A I n

sonon

on

sonon

s

TRL

LA

TRL

TA

21 ,

S4R SystemS4R System

SwitchLogic

n

Ipcn

Power Cell n

SwitchLogic

n

Ipcn

Power Cell 1

LoadBattery

PI control

Integrator

VMEA

VBEA

S3RS3R == Sequential Switching Shunt RegulatorSequential Switching Shunt Regulator S4RS4R == Sequential Switching Shunt Series RegulatorSequential Switching Shunt Series Regulator

Ladder ModelLadder Model

Vcmp1 Vcmp2 Vcmpn

VMEA

VBEA

Main Bus CurrentBattery Bus Current Power cell n

Power cell 2

Power cell 1

++

+VMEA Itotal

Ipcn

Ipc2

Ipc1Ipc

2 Ipc

n Ipc

Bus or BatteryComparators

Experimental Real-Time Experimental Real-Time SetupSetup

The test environment consists of The test environment consists of an AMD XP2400+ microcomputer an AMD XP2400+ microcomputer a Digilent Inc. XUP Virtex II Pro Development FPGA a Digilent Inc. XUP Virtex II Pro Development FPGA

Card with a 2VP30-7-FF896 Virtex II Pro FPGA. Card with a 2VP30-7-FF896 Virtex II Pro FPGA. The schematic of the simulation model was The schematic of the simulation model was

generated using Matlab/Simulink. generated using Matlab/Simulink. The VHDL simulation and the FPGA The VHDL simulation and the FPGA

synthesis/implementation phases were realized synthesis/implementation phases were realized using using Modelsim HDL simulator v6.1b from Mentor Graphics Modelsim HDL simulator v6.1b from Mentor Graphics and ISE Development System v8.1i from Xilinx and ISE Development System v8.1i from Xilinx

respectively.respectively.

Simulink/Matlab Simulink/Matlab ModellingModelling

Main Bus

Battery BusMain Bus Load

SolarPower Cells

Sequential Switching Shunt Series Regulator - S4R

VBEA Integrator

VMEA PI Controller

Continuous

pow ergui

v+-

Vout

v+-

VRSense

-C-

VPiRefBus

-C-

VIntRefBat

In1

In2

Conn2

Conn1

SolarArray4

In1

In2

Conn2

Conn1

SolarArray3

In1

In2

Conn2

Conn1

SolarArray2

In1

In2

Conn2

Conn1

SolarArray1

Scope1

Scope

RSense

RLoad2RLoad1

PGen

-K-

KpPiBus

-K-

KiPiBus

-K-

KIntBat

-K-

KBus

1s

Integrator1

1s

Integrator

g m

1 2

IdealSwitch

i+ -

IBus1

i+

-

IBus

CBus

Bat36V

Add3

Add1Add

Vout

Verror

VMEA

VMEA

VRSense

VBEA

VBEA

IBat

IBus

Power Cell ModelPower Cell ModelPower Switch #1

Power Switch #2

Solar Power Cell

Switch Logic

Main BusHystheresis

Battery BusHystheresis

2

Conn2

1

Conn1

NOT op3

AND

op2

AND

op1

g

ds

M3

g ds

M2

Isar2

D3

D2

Bus_Hist1

Bat_Hist

2

In2

1

In1

Vthy 1

S4R Main Bus Results S4R Main Bus Results (Matlab)(Matlab)

0 0.01 0.02 0.03 0.04 0.05

2

4

6

VM

EA

s4r1cell - Matlab/SymPowerSystems Simulation

0 0.01 0.02 0.03 0.04 0.050

2

4

IBu

s

0 0.01 0.02 0.03 0.04 0.0549.5

50

50.5

Vou

t

time(seconds)

Battery Bus Results Battery Bus Results (Matlab)(Matlab)

0 0.01 0.02 0.03 0.04 0.050

0.5

1

IBa

t

s4r1cell - Matlab/SymPowerSystems Simulation

0 0.01 0.02 0.03 0.04 0.050

5

10

VR

Se

nse

0 0.01 0.02 0.03 0.04 0.05

2.83

3.23.43.63.8

VB

EA

time(seconds)

Bus Error (Matlab)Bus Error (Matlab)

0.021 0.0215 0.022 0.0225 0.023 0.0235 0.024

6

6.5

7

VM

EA

s4r1cell - Matlab/SymPowerSystems Simulation

0.0215 0.022 0.0225 0.023 0.0235 0.024

3

3.5

4

IBu

s

0.0215 0.022 0.0225 0.023 0.0235 0.024

49.9

50

50.1

Vou

t

time(seconds)

Real Time Results (FPGA)Real Time Results (FPGA)

0.035 0.036 0.037 0.038 0.039 0.0449.8

50

50.2

Vou

t

S4r4CellGenVhdl1b - FPGA simulation @ Ts = 1us

0.035 0.036 0.037 0.038 0.039 0.04

0204060

Vbr

idge

1

0.035 0.036 0.037 0.038 0.039 0.04

0204060

VIp

an

el

0.035 0.036 0.037 0.038 0.039 0.04

0204060

VB

rid

ge2

0.035 0.036 0.037 0.038 0.039 0.04-1.5

-1-0.5

00.5

Ibri

dg

e2

0.035 0.036 0.037 0.038 0.039 0.04-0.5

00.5

11.5

IBu

s

time(seconds)

Real Time Results (FPGA)Real Time Results (FPGA)

0.03 0.035 0.04 0.045 0.0549.5

50

50.5

Vou

t

S4r4CellGenVhdl4b - FPGA simulation @ Ts = 1us

0.03 0.035 0.04 0.045 0.050

5

IBus

time(seconds)

DiscussionDiscussion

The simulator uses low cost The simulator uses low cost reconfigurable computing infrastructure reconfigurable computing infrastructure (e.g. embedded processors and FPGAs).(e.g. embedded processors and FPGAs).

It is capable of having simulation steps It is capable of having simulation steps on the order of 0.4 microseconds.on the order of 0.4 microseconds.

It is suitable to represent typical It is suitable to represent typical modern aerospace power systems. modern aerospace power systems.

We realized the simulation of a We realized the simulation of a sequential switching shunt series sequential switching shunt series regulator (S4R) system regulator (S4R) system

Future WorkFuture Work Probabilistic ModelingProbabilistic Modeling Capture of dynamic/transient faults Capture of dynamic/transient faults Couple simulator to a mixed formal Couple simulator to a mixed formal

method/simulation frameworkmethod/simulation framework Transition tool to a commercial productTransition tool to a commercial product Test other key modules (power and control) Test other key modules (power and control)

to be deployed in a lunar settlementto be deployed in a lunar settlement Add more modules for Add more modules for lunar settlementlunar settlement and and

aerospace applications to the VHDL library aerospace applications to the VHDL library