OSU Research Programs In Mechatronics · PDF fileOSU Mechatronics Lab. 1 OSU Research Programs In Mechatronics Systems ... OSU Mechatronics Lab. 2 ... Power Ratings of DGS unit 1 and

OSU Mechatronics Lab. 1

OSU Research Programs In Mechatronics Systems

Prof. Ali Keyhani

October 22, 2004 (IAB’04)

Mechatronics Systems LaboratoryDepartment of Electrical and Computer Engineering

The Ohio State University


Publications of the Year ’041. "Control of Distributed Generation Systems Part I: Voltage and Current

Control," IEEE Transactions on Power Electronics, Vol. 19, No. 6, November 2004, (M. N. Marwali and A. Keyhani)

2. "Control of Distributed Generation Systems Part II: Load Sharing," IEEE Transactions on Power Electronics, Vol. 19, No. 6, November 2004, (M. N. Marwali, J. W. Jung, and A. Keyhani)

3. "Composite Neural Network Load Models for Power System Stability Analysis," IEEE Power Engineering Society 2004 Power Systems Conference & Exposition, October 10-13, 2004, New York city, NY (Ali Keyhani; Wenzhe Lu; Gerald T. Heydt)

4. "Power Floe Control of a Single Distributed Generation Unit with Nonlinear Load," IEEE Power Engineering Society 2004 Power Systems Conference & Exposition, October 10-13, 2004, New York city, NY (Min Dai; Mohammad N. Marwali; Jin-Woo Jung; Ali Keyhani)

5. "Neural Network Modeling of Power System Loads," submitted to International Journal of Neural Systems (IJNS), July 2004, (Wenzhe Lu; Ali Keyhani; Gerald T. Heydt)

6. "Torque Ripple Analysis of a PM Brushless DC Motor Using Finite Element Method," IEEE Transactions on Energy Conversion, Vol. 19, No. 1 , Page 40-45, March 2004, (Dai, Min; Keyhani, A.; Sebastian, Tomy)

7. "A PWM rectifier control technique for three phase double-conversion UPS under unbalanced load," accepted for oral presentation on IEEE APEC'05, (Min Dai; Mohammad N. Marwali; Jin-Woo Jung; Ali Keyhani)

http://www.ece.osu.edu/ems/OSUpdf/FilesPdf/pes_dgspaper1.pdf




http://www.ece.osu.edu/ems/OSUpdf/FilesPdf/AKMethodologyNNLoadModeling.pdf




http://www.pscexpo.com/Papers/viewpapers.asp?papernum=04PS0574

http://www.pscexpo.com/Papers/viewpapers.asp?papernum=04PS0574

http://www.ece.osu.edu/ems/OSUpdf/FilesPdf/NNLoadModelingIJNS.pdf

http://www.ece.osu.edu/ems/OSUpdf/FilesPdf/MinTorqueRippleAnalysis.pdf

http://www.ece.osu.edu/ems/OSUpdf/FilesPdf/MinTorqueRippleAnalysis.pdf


Current Graduate Students

Nanda Marwali, PhD student, graduating December, 2004Min Dai, PhD student, graduating June, 2005Wenzhe Lu, PhD student, graduating June, 2005Jin-woo Jung, PhD student, graduating June, 2005


Outline

Control of Z-Source Power Converters for Fuel Cell SystemsControl of Power Converters for Distributed GenerationBy-Wire CarsModeling and Control of SRM in Electromechanic Brake Systems


Control of Z-Source Power Converter for Fuel Cell

SystemsPhD Student: Jin-Woo JungAdvisor: Prof. Ali Keyhani


I. Introduction

Future Trends of Electric Utility Industry


I. Introduction

Operating System For DGS


II. Distributed Genration Systems

Two Applications of Low Voltage DGS

(a) Grid-interconnection (b) Standalone AC power supply

Fig. 1 Configurations for two applications of DGS.


III. Single DGS UnitA. System Modeling

Circuit Model of Single DGS unit

Linv

Cinv Cinv

Delta-Wye Transformer

LOAD

U

V

W

x

z

n

y

aIinv

bIinv

cIinv

aIload

bIload

cIload

Cgrass

ca

bc

ab

VinvVinvVinv

cn

bn

an

VloadVloadVload

ca

bcVpwmVpwmVpwm

Vdc

gating signals DSP system voltages and currentsmeasurement

ab

Fig. 3 Circuit model for a single DGS unit.


A. System ModelingIII. Single DGS Unit

Equivalent Model of ∆/Y Transformer

DELTA-WYE TRANSFORMER

+

-

+

-

+

-

Ltrans

Ltrans

Ltrans

n

Rtrans

Rtrans

Rtrans

aIsnd

bIsnd

cIsnd

bIsndtr ⋅−

cIsndtr ⋅− aIsndtr ⋅−

u

v

w

x

y

zabVinvtr ⋅−

bcVinvtr ⋅−

caVinvtr ⋅−

Fig. 4 ∆/Y transformer model.



State equations in abc reference frame

abciinv

abcinv

abc sndITrC

invICdt

invVd rrr

⋅⋅

−⋅

=3

13

1

abcinv

abcinv

abc invVL

pwmVLdt

invId rrr

11−=

abcload

abcload

abc loadIC

sndICdt

loadVd rrr

11−=

abctran

abcvtran

sndtran

transabc loadVL

invVTrL

ILR

dtsndId rrrr

11−⋅+−=

[ ]Tcabcababc VinvVinvVinvinvV =r [ ]

[ ]Taccbba

Tcabcababc

IinvIinvIinvIinvIinvIinv

IinvIinvIinvinvI

−−−=

=r

where,

[ ]Tcbaabc IsndIsndIsndsndI =r[ ]Tcbaabc VloadVloadVloadloadV =

r

−−

−⋅=

010001100

trTrv[ ]Tcbaabc IloadIloadIloadloadI =r

−−

−⋅=

112211

121trTri



State equations in the stationary qd reference frame

0031

31

qdqdinv

qdinv

qd sndITriC

invICdt

invVd rrr

⋅⋅

−⋅

=

qdinv

qdinv

qd invVL

pwmVLdt

invId rrr

11−=

000 11

qdload

qdload

qd loadIC

sndICdt

loadVd rrr

−=

000 11

qdtran

qdqdtran

qdtran

tranqd loadVL

invVTrvL

sndILR

dtsndId

−⋅+−=r

r

[ ]

−⋅=⋅⋅= −

013031

23

2,11

0 trKTrKTri rowSisqd

−

−−=

5.05.05.0232305.05.01

32

SKwhere,

[ ]

−⋅=⋅⋅= −

0013

31

21

2,11 trKTrKTrv colSvsqd


B. Control System DesignIII. Single DGS Unit

Control Block Diagram

Outer Loop: Robust ServoMechanism VoltageController (RSC)

Inner Loop: Discrete-time Sliding Mode Current Controller (DSMC)

Robust ServoMechanismController Limiter Discrete Sliding Mode

Controller

( )krefV qd

r

+-

+

-

( )kloadV qd

r

Vqder

*qdcmdI

rqdcmdI

r

Iqder

( )kinvI qd

r

Line-to-LineVoltageSpaceVectorPWM

( )kpwmV qd

r

PWM timing

states states

Fig. 5 Overall control system.


C. Experimental ResultsIII. Single DGS Unit

System Parameters

Cgrass = 90 µFOutput Filter

Ts = 1/(3.2 kHz) = 320 µsSwitching/Sampling Period

Turn Ratio: 245 : 208Ltrans = 48 µH (≈ 0.03 p.u.), Rtrans = 0.02 Ω

∆/Y Transformer

Cinv = 540 µF, Linv = 300 µHInverter Filters

Vload = 208 V (LL-RMS), 120 V (LN)f = 60 Hz

AC Output Voltage

Vdc = 540 V (nom.) 390 V (min)DC Bus Voltages



Steady-state performance comparisonsbetween PI controllers and proposed controllers

(b) Proposed control methods(a) PI controllers

Fig. 8 Steady-state performance comparisons under nonliner load.(Top: three phase load currents. Bottom: Three-phase load voltages)



Steady-state linear load (1)

(a) 100% resistive balanced (b) 100% 0.8 p.f. load

Fig. 9 Steady-state linear load.(Top: load currents. Middle: Bottom: Three-phase load voltages)



Steady-state linear load (2)

(c) 100% resistive unbalanced (phase A unloaded) (d) 100% resistive unbalanced (phase A&B unloaded)

Fig. 10 Steady-state linear load.(Top: load currents. Middle: load voltages. Bottom: inverter voltages)



Transient Response

(a) 0% to 100% (b) 100% to 0%

Fig. 11 Resistive load transient.(Top: three-phase load currents. Bottom: three-phase load voltages)



Response of Three-Phase Short Circuits

Fig. 12 Three-phase short-circuits on output terminals.(Top: inverter currents. Middle: load voltages. Bottom: inverter voltages)



Output Voltage THD

2.7%Crest load (3:1)1.89%100% unbal. resistive (ph.A&B)1.70%100% unbal. resistive (ph.A)1.32%100% 0.8 pf load1.30%100% balanced resistive load0.90%No load

Output voltages THDTYPES OF LOAD


IV. Two DGS UnitsA. System Configuration

Circuit Model of Two DGS units

Fig. 13 Circuit model for two DGS units.


B. Control RequirementsIV. Two DGS Units

Complex Power at the load due to inverter i*iiii IVjQPS ⋅=+=

*sincos

−+=∴

i

iiiii Lj

VjEEVS

ωδδ*

* sincos

−+=

i

iiiii Lj

VjEEI

ωδδ

ii

ii LVE

P δω

sin=i

iii L

VVEQ

ωδ 2cos −

=

Active and Reactive Power flowing from the i-th inverter

11 δ∠E 22 δ∠E

1Ljω 2Ljω

0∠V

1I 2I

Fig. 14 Two inverters connected to a load.


B. Control RequirementsIV. Two DGS Units

Control variables for P and Q

P → power angle “δ”

Q → inverter output voltage “E”

Control Contraints

Locally measurable feedback signals (voltages/currents)

Data communications between each DGS about real power and reactive power

Wire impedance mismatches between inverter output and load bus

Voltage/current sensor measurement error mismatches

Tie-line impedance between loads


D. Simulation ResultsIV. Two DGS Units

Case 1Power Ratings of DGS unit 1 and 2: 600 kVA, respectivelyLoad 1: Pload1 = 480 kW/ Qload1 = 360 kVar (p.f. = 0.8)Load 2: Pload2 = 480 kW/ Qload2 = 360 kVar (p.f. = 0.8)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

100

200

300

400

500

600

Time [s ec]

P1, P

2 [kW

]

Two Active P owers

P 1P 2

(b) Real Powers (P1 and P2) 1.9 1.91 1.92 1.93 1.94 1.95 1.96 1.97 1.98 1.99 2

-1000

-800

-600

-400

-200

0

200

400

600

800

1000

Time [s ec]

I L1, I

L2 [A

]

Two Load Currents (Trans ient)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

100

200

300

400

500

600

Time [s ec]

Q1, Q

2 [kva

r]

Two Reactive P owers

Q1Q2

(a) Load currents (IL1 and IL2)

(c) Reactive Powers (Q1 and Q2)

Fig. 19 Simulation Results for Case 1.



Case 2Power Ratings of DGS unit 1 and 2: 600 kVA, 500 kVA, respectively

1.9 1.91 1.92 1.93 1.94 1.95 1.96 1.97 1.98 1.99 2-1000

-800

-600

-400

-200

0

200

400

600

800

1000

Time [s ec]

I L1, I

L2 [A

]


0 0.2 0.40

100

200

300

400

500

600

P1, P

2 [kW

]

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

100

200

300

400

500

600

Time [s ec]

Q1, Q

2 [kva

r]

Two Reactive Powers

Q1Q2

(a) Load currents (IL1 and IL2) (b) Real Pow


Load 2: Pload2 = 400 kW/ Qload2 = 300 kVar (p.f. = 0.8)Load 1: Pload1 = 480 kW/ Qload1 = 360 kVar (p.f. = 0.8)

0.6 0.8 1 1.2 1.4 1.6 1.8 2Time [s ec]

Two Active P owers

P 1P 2

ers (P1 and P2)




Case 3Power Ratings of DGS unit 1 and 2: 600 kVA, respectively

Load 2: Pload2 = 240 kW → 480 kW (after 1.6s), Qload2 = 180 kVar → 360 kVarLoad 1: Pload1 = 480 kW/Qload1 = 360 kVar (p.f. = 0.8)

1.4 1.5 1.6 1.7 1.8 1.9 2-1000

-800

-600

-400

-200

0

200

400

600

800

1000

Time [s ec]

I L1, I

L2 [A

]


1.4 1.5 1.6 1.7 1.8 1.9 20

100

200

300

400

500

600

Time [s ec]

Q1, Q

2 [kva

r]


Q1Q2

(a) Load currents (IL1 and IL2)


1.4 1.5 1.6 1.7 1.8 1.9 20

100

200

300

400

500

600

Time [s ec]

P1, P

2 [kW

]

Two Active P owers

P 1P 2

(b) Real Powers (P1 and P2)




Case 4: Nonlinear load

1.5 1.51 1.52 1.53 1.54 1.55 1.56 1.57 1.58 1.59 1.6-800

-600

-400

-200

0

200

400

600

800

Time [s ec]

I L1, I

L2 [A

]


0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

50

100

150

200

250

300

350

400

450

500

Time [s ec]

P1, P

2 [kW

]

Two Active P owers

P 1P 2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.60

50

100

150

200

250

300

350

400

450

500

Time [s ec]

Q1, Q

2 [kva

r]


Q1Q2

(a) Load currents (IL1 and IL2) (b) Real Powers (P1 and P2)


Power Ratings of UPS unit 1 and 2: 600 kVA, respectivelyLoad 1: Three-Phase Bridge Diode (CDC1 = 10000 µF and RL1 = 3.25 Ω) Load 2: Three-Phase Bridge Diode (CDC2 = 10000 µF and RL2 = 3.25 Ω)



E. Experimental ResultsIV. Two DGS Units

System Parameters

Cgrass = 90 µFOutput Filter

Ts = 1/(3.2 kHz) = 320 µsSwitching/Sampling Period

Turn Ratio: 245 : 208Ltrans = 48 µH (≈ 0.03 p.u.), Rtrans = 0.02 Ω

∆/Y Transformer

Cinv = 540 µF, Linv = 300 µHInverter Filters

Vload = 208 V (LL-RMS), 120 V (LN)f = 60 Hz

AC Output Voltage

Vdc = 540 V (nom.) 390 V (min)DC Bus Voltages



Steady-state linear load sharing performance

(b) Unbalanced resistive load(a) Balanced resistive load

Fig. 23 Steady-state linear load sharing.(Each trace box: per-phase load voltage and two units’s output currents)



Steady-state nonlinear load sharing performance

Fig. 24 Steady-state nonlinear load sharing.(two units’s output currents for phase a, b, c)



Dynamic load sharing performance

(a) 0% to 100% (b) 100% to 0%

Fig. 25 Resistive load transient.(two units’s output currents for phase a, b, c)



Different load applied on each phase

Fig. 26 Unit 2 is reconnected with different load applied on each phase. (Phase a and b : linear resistive load. Phase c: single-phase non-linear load.)


V. Conclusions

Standalone AC Power Supply

Design of Three Controllers: Voltage, Current, and Power Controller

Good Performance for Single DGS Unit and Two DGS Units

Nearly zero steady-state voltage (RMS) error

Low Total Harmonic Distortion (THD)

Fast/no-overshoot current response

Good voltage regulation

Good load sharing by P and Q control

OSU Mechatronics Lab.

Modeling and Control of a Fuel Cell Based Z-source Converter for Distributed Generation Systems

1. Conventional Topology: a DC-DC boost converter and a DC/AC inverter DSP controller: two controllers (DC/DC and DC/AC power converters)Power devices: ⇒ DC to DC boost converter: four power switches and four diodes⇒ DC to AC inverter: six power switchesSensors: DC input, DC output, and AC output

FuelCell(Vin)

S1 S3

S4 S2

S1 S3

S4 S6

3-phaseload

S5

S2

DC to DC boost converter DC to AC inverter

Fig. 1 Conventional system configuration.


2. Conventional Z-source Topology

Conventional Z-source converter: Impedance source (L-C) and a DC/AC inverterBoosted by shoot-though zero vectors (both switches turned-on)Open-loop control under only linear/heavy loadDynamic load applications like motorFuel cell modeled by a DC voltage source (battery)

Fig. 2 Conventional Z-source converter.


3. Proposed Z-source Topology

Proposed Z-source converter:Static load applications with fixed peak voltage/frequency (i.e., three-phase AC 208V and 60 Hz)Dynamic response of fuel cell considered System modeling/modified SVPWM implementation/closed-loop control system designGood performance under both linear load and nonlinear loadWide range of load, i.e., light load to a full load

Fig. 3 Proposed Z-source converter.


5. Entire Control Loop Structure

Fig. 5 Total control system block diagram.

where, Three controllers1. Discrete-time Optimal Voltage Controller2. Discrete-time Sliding Mode Current Controller (DSMC) 3. Discrete-time PI DC-link Voltage Controller

One observer1. Asymptotic Observer for estimation of load currents


Control of Power Converters for Distributed Generation

Ph.D. Student: Min DaiAdvisor: Prof. Ali Keyhani


Problem Statement (1)

• Power control of grid-connected inverters– Single unit with grid-connection

• No load connection• Disconnection• Reclose

– Multiple units• Parallel operation in island mode• Connect a 2nd unit to a grid-connected unit• Disconnections• Reclose


System Description (1)

• Power circuit topology– Single unit (3-ph 3 wire inverter plus transformer)


System Description (2)

• Power circuit topology– Multiple

units


PQ Control with Grid-Connection (1)

• Real & reactive power control in grid-connected mode

• Operating scenarios-single unit– Connection with no load:

• Synchronization before closing the switch

• Control strategy change while closing the switch

• Insignificant transient due to low inverter output impedance

InverterUnit

GridLocalLoad

jX



InverterUnit

GridLocalLoad

jX– Disconnection with load:

• Three phase opened one by one due to zero-cross switching

– Reclose• Synchronization• Control strategy

switch• P,Q transient exists

due to non-zero X

InverterUnit

GridLocalLoad

jX



• Operating scenarios-multiple units– Parallel in island mode:

• Synchronization• Load sharing after

connection• Harmonic load sharing

– Connect a 2nd unit• Synchronization• Load sharing operation

InverterUnit 1

GridLocalLoad

jX

InverterUnit 2

InverterUnit 1

GridLocalLoad

jX

InverterUnit 2



– Disconnections with load:

• Three phase opened one by one due to zero-cross switching

InverterUnit 1

GridLocalLoad

jX

InverterUnit 2

InverterUnit 1

GridLocalLoad

jX

InverterUnit 2



– Reclose• Synchronization in

parallel• Control strategy

switch• Fundamental and

harmonic load sharing before and after switching

• P,Q transient exists due to non-zero X

InverterUnit 1

GridLocalLoad

jX

InverterUnit 2



• Control goals– Low steady state PQ tracking error– Relatively fast transient response– Steady state decoupling between P and Q

controls– Small PQ transient at reclose– Load sharing in island mode including harmonic

load sharing– Load sharing in grid-connected mode– As less control interconnections between the units

as possible


Mechatronics in Automotive Systems Mechatronics in Automotive Systems Embedded DSP/microcontrollersEmbedded DSP/microcontrollers

Active suspensioncontrol

Thermal managementsystem control

Electric motor drive controlin hybrid electric car

IC Engine control

Power steering andtraction control

Adaptive comfortcontrol :heat,ventilatiion,air condition

Active noise cancellation


Brake-By-Wire

• Brake-by-wire does everything:– Braking– ABS – Antilock brake system– Brake power assisting– Vehicle stability enhancement control– Parking brake control– Tunable pedal feeling


Application of Embedded System to Brake-By-Wire

• Plug-in modules for Brake-By-Wire


Application of Embedded System to Brake-By-Wire• EMB: Electromechanical Brake Actuators• BBWM: Brake-By-Wire Manager


Application of Embedded System to Brake-By-Wire• System structure

DSP based Controller

Motor Gear and Screw

Caliper

Force Sensor

TV FclFd

Position Sensor


Application of Embedded System to Brake-By-Wire

• Electromechanically actuated disk brake by ITT Automotive


Application of Embedded System to Brake-By-Wire• Control of brake-by-wire system

– Four-quadrant operation of servo-motor– Desired clamping force response– Torque ripple minimization– Elimination of rotor position sensor– Elimination of clamping force sensor– Fail-safe operation


Steer-By-Wire

• Not just electrically assisted power steering

• Steer-by-wire comes in two flavors:– Front steer– Rear wheels

• Cars with steer-by-wire may not even have a driver’s wheel


Application of Embedded System to Steer-By-Wire

• Only wires may relay signals from a car’s steering wheel to its front wheels in a front steer-by-wire system. And an electrically actuated motor, not a mechanical link with the steering wheel, turns the front wheel.


Research @ OSU• Experimental setup


Modeling and Control of SRM in Electromechanic Brake

System

Wenzhe Lu, Ph.D. studentAli Keyhani, Advisor


Project Goal and Objective• Overall project goal:

Develop and implement a low-cost drive system consisting of a sensorless switched reluctance motor (SRM) with power converter and controller.

• Objectives:1. Four-quadrant operation2. Clamping force response3. Torque ripple minimization4. Elimination of rotor position sensor5. Elimination of clamping force sensor6. High performance, low cost7. Fault tolerance


Inductance Model of SRM for Standstill and Online Operation

(a) Standstill (b) Online Operation

)k(v)1k(X)(C)1k(Y)k(w)k(u)(B)k(X)(A)1k(X

s

ss

++⋅θ=++⋅θ+⋅θ=+&

X=[i1, (,i2)] Y=[i] u=[V] θs=[R, L (,Rd, Ld)]w: process noise v: measurement noise


Parameter Identification of SRM Using Maximum Likelihood

Maximum Likelihood Estimation

phase winding to be estimated

phase winding model

maximum likelihood estimation

input u output y

estimated output

errorestimated

parameter R, L

+_


Experimental Setup with dSPACE DS1103


Parameter Estimation ResultsInductance and Flux Linkage


Sensorless ControlAn inductance model of SRM can be used to design sensorless controller for full speed range.When speed is above 20RPM, a sliding mode observer based sensorless controller can yield satisfactory results.At near zero speeds is, the turn-on position for next phase and the turn-off position for current phase can be determined by matching inductances.At standstill, rotor position can be estimated by applying voltage pulses and comparing peak current values.

I

I

ControllerController SRMSRM

SRMmodelSRMmodel

ObserverObserver

V

+_

θ ω


4-Q Torque and Force Control in EMB System

System structure

Four-quadrant operationForce control and torque ripple minimizationSensorless operation (no rotor position sensors)

switchingsignal

SRMSRMControllerController InverterInverter PlantPlant

V,I T,θFFcmd

ObserverObserverθ, ω


4-Q Torque and Force Control in EMB System

Two control loops + torque controlOuter loop: force control (PID)

Inner loop: current control (Hysteresis)

Force control (PID)

Torque control

Current control (Hysteresis)

Tcmd Icmd

VSRM and Brake system

Fcmd

Fcl

I

ObserverObserverθ, ω


4-Q Torque and Force Control in EMB – Simulation Results

0 0.05 0.1 0.15 0.2 0.250

500

1000

1500

2000

2500Force (N)

time (s )

(a) Clamping Force Response

-0.5 -0.4 -0.3 -0.2 -0.1 0 0.1 0.2 0.3 0.4-40

-20

0

20

40

60

80

100

120

140

160

T (Nm)

w (rad/s )

(b) Torque-Speed Curve


Conclusions

• Four Ph.D students will graduate in 2005.• We could continue our research if industry

could support us.• Our support has gone to zero since 2001.• Outsourcing?• Could we do some of your outsourcing

Research Projects?

Documents

OSU Research Programs In Mechatronics · PDF fileOSU Mechatronics Lab. 1 OSU Research Programs In Mechatronics Systems ... OSU Mechatronics Lab. 2 ... Power Ratings of DGS unit 1 and