Presented by Youngkook Lee, December 04, 2006 A S TATOR T URN F AULT T OLERENT S TRATEGY FOR I...

Presented by Youngkook Lee, December 04, 2006

A STATOR TURN FAULT TOLERENT STRATEGY

FOR INTERIOR PM SYNCHRONOUS MOTOR

DRIVES in SAFETY CRITICAL APPLICATIONS

Youngkook Lee

Professor Thomas G. Habetler

School of Electrical and Computer EngineeringGeorgia Institute of Technology

Atlanta Georgia

2Presented by Youngkook Lee, December 04, 2006

Outline

Part 1. Introduction

Background of the Research

Problem Statement and Research Objective

Survey on Previous Work

Part 2. Proposed Work

Modeling of an IPMSM with Stator Turn Faults

Turn Fault Tolerant Strategy

Part 3. Conclusions and Future Work


Interior PM Synchronous Motors (IPMSMs)

Features Having large power (torque) density, wide constant power-speed ratio, and high

efficiency

Creating special challenges under any fault condition due to the presence of

permanent magnets that cannot be turned off at will

Requiring special care in safety critical applications where any failure can result in

serious accidents

Permanent Magnet

Rotor

Stator

Cross-Sectional View


Fault Tolerance

Defined as a performance characteristic that a fault in a component or sub-system does not cause the overall systems to malfunction

Quantified in terms of “reliability and availability”

Increased conventionally by “conservative design and

redundancy”; however, these approaches increase the

cost and complexity of the system

Recently, increased via “fault diagnosis and tolerant

strategies”; however, focusing on how to detect a fault,

while the research on how to increase the availability

remains uncharted area


Stator Turn Faults

Referring to the insulation failures in several turns of a stator coil within one phase

Generating excessive heat in the shorted turns due to a large circulating current

Developing rapidly into the catastrophic failures

Initiating a large portion of stator winding-related failures

that attribute to about 35~37% of induction machine

failures


Outline










Problem Statement and Objective Research

The primary objective of this research is to develop a stator turn fault tolerant strategy in IPMSM drives satisfying the following requirements:

The ultimate goal of this research is to develop a complete solution for high turn fault tolerance of IPMSM drives in safety critical applications including modeling, detection method, and tolerant strategy

Preventing a turn fault from developing into the destructive phase

Not resulting in the complete loss of the availability of the drive

under a turn fault condition

Not requiring any change in the standard IPMSM drive

configuration


Outline










Approaches in Previous Work

Since it is generally accepted that there is no way to prevent turn faults from developing destructive phase except for stopping the machine completely, a small amount of work has been done in the following three ways:

Redundancy

Development of fault tolerant machines

Post-fault operations for stopping the faulty machine without further damage


Redundancy Approach

LoadMotor 1 Motor 2

Position sensor 2

Position sensor 1

Inverter 1 Inverter 2

DC source 1

DC source 2

Controller 1 Controller 2

Gate signal Gate signal

Back up Controller


Fault Tolerant Machines

Requirements for Fault Tolerant Machines Complete electrical isolation between phases

Implicit limiting of fault currents

Magnetic isolation between phases

Physical isolation between phases

More than 3-phases

Switched Reluctance Motors (SRMs) Coming close to achieving the requirements

Having inherently large acoustic noise and vibration, and low

efficiency

Requiring a different converter topology from the standard 6-

switch full bridge inverter

1



Converter Topologies for Conventional 3-phase motors and SRMs

(a) Conventional 3-phase Motors (b) SRMs

2



Modular Fault Tolerant PM Motors

Combining the advantages of PM motors and SRMs

Being subjected to stator turn faults due to the presences of the permanent magnets

Requiring the same converter topology as SRMs

3


Post-Fault Operations

Free-Running Mode

Not being an appropriate post-fault operation for IPMSMs

Possibly being subjected to a critical damage on the dc-link due to unregulated generating power in high speed ranges

Resulting in the loss of the control over the speed and torque

ia

ea

VDC A B C

D4 D6 D2

ib ic

eb ec

O

n

D3 D5D1

1


Post-Fault Operations

Symmetrical Short-Circuit Operation

Being a good choice for post-fault operation for IPMSMs

Resulting in the loss of the control over the speed and torque

ia

ea

VDC A B C

D4 D6 D2

ib ic

eb ec

O

n

2


Outline










Demands for Modeling An accurate model is required to develop an effective detection

method or tolerant strategy

A test-bench for confirming any fault detection scheme or tolerant

strategy is required since even a minor deficiency can result in a

serious damage to the drives


Approaches in Modeling of Electric Machines Finite element analysis (FEA) based models

Accurate, but take long time for simulation and require detail

specification of the machine

Equivalent circuit-oriented models

Simple, but less accurate and difficult to consider non-linearity in

the magnetic system

1


A Circuit-Oriented Model of IPMSMs with Turn Faults Being derived in phase-variables

Being integrated with a vector-controlled drive model since almost

IPMSM applications utilize current-controlled inverters

Being used to investigate the behaviors of a stator turn fault in an

IPMSM drive


Basic assumptions for the henceforth analysis Each phase winding consists of turns connected in series, and the

3-phase windings are Y-connected with a floating neutral

A stator turn fault occurs on the a-phase winding

2


Q1 Q3 Q5

Q4 Q6 Q2

D1 D3 D5

D4 D6 D2

the number of the shorted turns

the number of turns per phase

Schematic Diagram of an IPMSM drive with a turn Fault

ia

ib ic

a

bc

as1

as2 if

ia

ib ic

a

bc

Rfia- if


Machine Equations under Fault-Free Conditions

Stator Line-Neutral Voltages

Developed Torque

r rr

d d d

dt dt dt

s s PMs s s s s

i Lv r i L + i

( ) ( )( )

(1)

1= +

2 2r r

er r

d dPT

d d

T Ts PMs s s

Li i i

( ) ( )

where, , , [ ]a b cdiag r r rsr

( ) ( ) ( )

( ) ( ) ( )

( ) ( ) ( )

aa r ab r ac r

r ba r bb r bc r

ca r cb r cc r

L L L

L L L

L L L

sL( ) _ _ _[ ( ) ( ) ( )]Tr a PM r b PM r c PM r PM ( )=

P is the number of poles, r represents the rotor position in electrical radians.

(2)

[ ]Tan bn cnv v vsv [ ]Ta b ci i isi

1


Machine Equations under Fault-Free Conditions

Stator Self- and Mutual Inductances

Flux Linkages Contributed by Permanent Magnets

1 21

1 21

1 21

( ) cos(2 ) ( )

2( ) cos[2 ( )] ( )3

4( ) cos[2 ( )] ( )3

aa r l k r l am rk

bb r l k r l bm rk

cc r l k r l cm rk

L L L L k L L

L L L L k L L

L L L L k L L

1 21

1 21

1 21

1( ) ( ) cos[2 ( )]32

1( ) ( ) cos[2 ( )]

2

1( ) ( ) cos[2 ( )]32

ab r ba r k rk

bc r cb r k rk

ca r ac r k rk

L L L L k

L L L L k

L L L L k

(a) Self inductances (b) Mutual inductances

2 11

sin[(2 1) ]

2sin[(2 1)( )]32sin[(2 1)( )]3

r

r k rk

r

k

k

k

PM( )=

2


Machine Equations under Turn Fault Conditions


Developed Torque

r rr

d d d

dt dt dt

' ' '

' ' ' ' 's s PMs s s s s

i Lv r i L + i

( ) ( )( )

1= +

2 2r r

er r

d dPT

d d

' ''T ' 'Ts PMs s s

Li i i

( ) ( )

where,

(1 ) 0 0 0

0 0 0

0 0 0

0 0 0

s

s

s

s

r

r

r

r

'sr

2

2

(1 ) (1 ) ( ) (1 ) ( ) (1 ) ( ) (1 ) ( )

(1 ) ( ) ( ) ( ) ( )( )

(1 ) ( ) ( ) ( ) ( )

(1 ) ( ) ( ) ( ) ( )

l am r am r ab r ac r

am r l am r ab r ac rr

ab r ab r l bm r bc r

ac r ac r bc r l cm r

L L L L L

L L L L L

L L L L L

L L L L L

'SL

1 2

T

as as bn cnv v v v'sv

T

a a f b ci i i i i 'si

_ _ _ _(1 ) ( ) ( ) ( ) ( )T

r a PM r a PM r b PM r c PM r 'PM( )=

(3)

(4)

1



* Rearranging (3) and (4) yields


Developed Torque

( ) ( ) ( ) ( ) ( )1

2

( ) ( )1

2T TS r sr r

2 2aa r ar r aa r ab r ac r

s s sr

f f f a b cr r r r

e

r

r

dL θ dλ θ dL θ dL θ dL θ+ μ i - μi - μi i +i +i

dθ dθ dθ d

d θ d θ+

dθ dθPT =

2

θ dθ

L λi i i

(5)

(6)

( ) ( )0 ( )

( ) ( )

( )0 ( ) ( )

s aa r aa rff ab r e ab r f

rac r a

s s r sr rs s s s e s e

r

r r

c

r L θ L θdi dμ i L θ +ω L θ i

dt dθL θ

d d θ d θω ω

dt dθ dθ

L θ

i L λ

v r i L i

2



Voltage Equation at the Healthy Turns

Voltage Equation at the Shorted Turns

Summation of the Line-Neutral Voltages

(7)

(8)

( ) ( )( )

( )( )

( )

s a r a rs a a r e s e

r ras1

f am ram r e f

r

d d θ dλ θr i + θ +ω +ω

dt dθ dθv = 1 μ

di dL θμ L θ +ω i

dt dθ

i LL i

2

e e

e

( ) ( )+ + +

= ( )

( )

as f f

s a r ar rs a a s

r r

f am rs f ls am r f

r

v R i

d d dr i

dt d ddi dL

r i L L idt d

i LL i

+ fan bn cn s f ls

div v v r i L

dt

(9)

3


Implementation of a simulation model

Block Diagram of the Simulation model

Discrete PI

controller

S-function(anti-windupPI with feed-

forwardcontroller)

Phase-variableModel

MotionEquation

Speed controller

Currentcontroller

Phase voltage generator IPMSM

sv eT*sov*

eT

r

*r

, ,, ,r e a b ci , ,,e a b ci

Load

Pole to phase


Key Parameters for Specifying the Model

Class Item Unit Values

Motor

Pole Number [ - ] 8

Rated /Max. Torque [Nm] 40 / 80

Rated Current [A] 114 / 250

Rated Speed [rpm] 2450

Stator Resistance [mohm] 4.85

Stator Leakage Inductance [uH] 18.9

Stator Magnetizing Inductance [uH] L1 : 167.4, L2: -33

PM Flux Linkage [Wb] 0.0543

Inverter

Nominal dc-Link Voltage [Vdc] 216

Switching Frequency [kHz] 7

Current Control Rate [kHz] 7


Simulation under Various Rotating Speeds

Simulation Conditions and Summary of the Results

Items Unit Values

Load Torque [Nm] 20

Rotating Speed [rpm] 1500 2450 3500

Fault Fraction [%] 1

Fault Impedance [ohm] 0 ( a bolted fault)

Circulating current [A] 1621 1650 1678

Sequence components in line-neutral voltages

Positive

[V]

35.58 57.67 82.26

Negative 1.2 1.93 2.72

Zero 0.12 0.19 0.27

Sequence components in line currents

Positive[A]

62.30 61.95 61.85

Negative 2.18 4.77 6.8

TorqueFund.

[Nm]20 20 20

2nd order 1.77 1.40 1.37



Items Unit Values

Load Torque [Nm] 0 40 80

Rotating Speed [rpm] 1500

Fault Fraction [%] 1


Circulating current [A] 1532 1813 2218


Positive

[V]

33.41 39.85 48.67

Negative 1.11 1.33 1.61

Zero 0.11 0.13 0.16


Positive[A]

2.57 117.09 211.20

Negative 1.24 3.04 3.75

TorqueFund.

[Nm]0 40 80

2nd order 1.63 2.27 3.61

Simulation under Various Loads



Simulation under Various Fault Fractions

Items Unit Values

Load Torque [Nm] 40

Rotating Speed [rpm] 1500

Fault Fraction [%] 0 1 3 5


Circulating current [A] 0 1813 1630 1483


Positive

[V]

40.82 39.55 38.20 36.83

Negative 0 1.33 3.61 5.52

Zero 0 0.13 0.35 0.55


Positive[A]

113.07 117.09 124.72 131.84

Negative 0 3.04 8.32 12.76

TorqueFund.

[Nm]40 40 40 40

2nd order 0 2.27 6.38 9.99


Characteristics of Turn Faults in Current-Controlled Inverter-Driven Applications

A Stator turn fault induces a large circulating current in the shorted turns that has the following characteristics :

1

The fundamental frequency is the same as the synchronous

frequency

The current generates magnetic flux that acts against the main air-

gap flux. In the case of a stator turn fault where a large number of

turns are shorted, the additional flux can be large enough to

demagnetize the permanent magnets

The amplitude is strongly related to the amplitude of the stator

line-neutral voltages, while fault fraction has very little effect

The current is mainly limited by the stator resistance and leakage

inductance


Characteristics of Turn Faults in Current-Controlled Inverter-Driven Applications

A Stator turn fault in current-controlled inverter-driven applications induces …

2

Decreased positive sequence and increased negative sequence

voltages since the inverter tries to control the currents so as to

follow their references by reducing positive sequence voltage and

compensating negative sequence voltage

Reduced positive sequence impedance, and increased negative sequence

and coupling impedances as the same as those in line-fed applications

A circulating current that decreases as fault fraction increases,

because the amplitude of current is nearly proportional to the

amplitude of the stator line-neutral voltage and negative sequence

voltage is much smaller than positive sequence voltage


Outline










Theoretical Foundations

Relation between and (Stator Voltage)

Rearranging the voltage equation (8) at the shorted turns yields

Generally, the asymmetry introduced in the stator voltages due to

a stator turn fault has a small effect on the overall stator voltage;

thus

0( )( ) f f am r

f s f ls am r e f asr

R di dLi r i L L i v

dt d

where, represents the instantaneous value of the line-neutral

voltage at the faulty winding.

0asv

fi sv

where, represents the stator voltage vector. sv

1 2( 3 )ff s e ls s

Ri r j L L L v

1

1

(11)

(12)


Theoretical Foundations

Relation between and (Stator Voltage)

The amplitude of the circulating current in the shorted turns is

Three Options for

(1) Increasing the fault impedance

(2) Increasing the resistance and leakage inductance of the stator

winding

(3) Reducing the stator voltage vector

fi sv

1 2[ ( 3 )]

sf

fs e ls

vi

Rr j L L L

2

2

(13)


Machine Equations in the qd-variables in a steady State Condition under Fault-Free Condition

Stator Voltage

Developed Torque

3

2 2e e e

e PM qs d q ds qs

PT i L L i i

( ) ( )

e es qs ds

e e e es qs ds e q qs e d ds PM

v v jv

r i ji j L i L i

Theoretical Foundations 3

(14)

(15)


Theoretical Foundations 4

Representation in Circle Diagram

di

qi

Constant torque hyperbola, 0eT

Voltage Ellipse, in the case that

Maximum Torque-per-Amp Trajectory

(Motoring)

PM

dL

Current circle, in the case that 0 0 and e e e e

ds ds qs qsi i i i A

0 0 and e e e eds ds qs qsi i i i

di

qi

Constant torque hyperbola, 0eT

Voltage Ellipse, in the case that

Maximum Torque-per-Amp Trajectory

(Motoring)

PM

dL

Current circle, in the case that 0 0 and e e e e

ds ds qs qsi i i i A

B

Current circle, in the case that * * and e e e e

ds ds qs qsi i i i

0 0 and e e e eds ds qs qsi i i i

Voltage Ellipse, in the case that* * and e e e e

ds ds qs qsi i i i


Development of the Proposed Strategy

From the torque equation, the q-axis current is expressed as a function of the d-axis current under a given torque condition as,

Inserting into the stator voltage vector equation yields,

The specific combination of the d- and q-axis currents minimizing , consequently, minimizing the circulating currents can be determined by solving

0* 1

** 2

3[ ( ) ]

2 2

e eqs e

e dsPM d q ds

T Ci

P C iL L i

2 21 1

2 2

[ ( )] [ ]s e d PM s e q

C Cv r L i r i L

C i C i

e* e*

s ds dse* e*ds ds

2

0v

i

s

e*ds

(16)

(17)

(18)

sv


Extension to Induction Motor Drives

From the induction motor torque and slip equations,

By inserting (19) and (20) into voltage equation,

By solving the following equation,

(19)

(20)

01

3(1 )

4

e

s

T Ci

P iL i

e*qs e*

e* dsds

** * * * 2

2( )

eqsr

e m sl m mr

ir C

L i i

e* e*ds ds

2 * 2 * 21 2 2 12 2

[ ( ) ] [ ( ) ]( ) ( )s m s s m s

C C C Cv r L i r i L

i i i i e* e*

s ds dse* e* e* e*ds ds ds ds

(21)

2

0v

i

s

e*ds

(22)


Simulation for Comparing with MTPA Operation

Simulation Conditions : Optimal d- and q-axis Current trajectories for reducing the

stator voltage

(a) d-axis current (b) q-axis current

1[%], and 0 (a bolted fault)fR

1



Comparison of

(a) In the case of MTPA operation (b) In the case of

the proposed strategy

fi

2



Comparison of Available Operating Areas with Limiting within 3 Times the Rated Current

MPTA operation : red circle markedProposed strategy : blue x marked

No

rmal

ized

T

orq

ue

Normalized speed

fi

3


Machine Equations in the qd-Variables under Symmetrical Short-Circuit Operation

Stator Voltages

Stator Currents

Developed Torque

22 2

1es e PMqs

ee q PMs e q dds

riLr L Li

32

_ 2 2 2 2 2

3[ ( ) ]

2 2 ( )q ee

e sym s PM d qs e q d s e q d

LPT r L L

r L L r L L

( )0

0

e ees qs e d ds PMqs

e ees ds e q qsds

r i L iv

r i L iv

Simulation for Comparing with Symmetrical Short-Circuit Operation

1

(23)

(24)

(25)


Comparison of

Time (sec)

Circulating current in the shorted turns

In the case of the proposed

strategy

Cu

rren

t (A

)

In the case of symmetrical short circuit operation


fi

2


Comparison of the a-phase Currents

Time (sec)

a-phase current


strategy

Cu

rren

t (A

)



3


Comparison of the a-phase Line-Neutral Voltages

Time (sec)

a-line to neutral voltage


strategy

Vo

ltag

e (V

)



4


Comparison of the Developed Torque

Time (sec)

Developed torque


strategy

To

rqu

e (N

m)



5


Effects of the Machine Specifications

Items Unit #1 #2 #3 Remark

Pole Number [ - ] 8

Max. Current [A] 300 Inverter Max. Current

Rated Speed [rpm] 2450

DC-link Voltage [Vdc] 216

Stator Resistance [mΩ] 4.85

Leakage Inductance [uH] 33

d-axis Inductance [uH] 220 311 127

q-axis Inductance [uH] 440 622 287

Saliency Ratio [ - ] 2 2 2.26

PM Flux Linkage [Wb] 0.0543 0.0384 0.0543

Char. Current [A] 247 123 428

Parameter Lists of Different Machine Designs

1



To

rqu

e (N

m)

Speed (rpm)

Blue solid line : #1Red dotted line : #2Black dashed line : #3

Torque-Speed Characteristic Curves

2



Comparison of under MTPA Operationfi

(a) In the case of Design #1 (b) In the case of Design #2

(c) In the case of Design #3

3



Comparison of under the Proposed Strategy Operationfi

(a) In the case of Design #1(b) In the case of Design #2


4



Comparison of under the Proposed Strategy Operationsi

(a) In the case of Design #1(b) In the case of Design #2


5


Experimental Results-Preliminary

Experimental Conditions Motor : 5HP Induction Motor

Rotating Speed and Load : 800 rpm, 5 Nm (0.25 rated torque) Fault Conditions : 1.03[%], and 0 (a bolted fault)fR

(a) Specially rewound induction motor (b) Diagram of test bench

1



Transition of Operating Modes

(a) Ch. 4: Rotating speed (400 rpm/V),

Ch. 3: (5 A/V), Ch. 1: (5 A/V), Time (500 ms/div)

(b) Ch.1: (50A/10mV),

Ch. 2: (10 A/10mV), Time (200 ms/div)edsi

eqsi

fi

ai

2



Steady-State Conditions

Ch.1: (50A/10mV), Ch. 2: (10 A/10mV), Time (200 ms/div)fiai

(a) before activating the proposed Strategy (b) after activating the proposed Strategy

3


Outline










Conclusions

A stator turn fault in an IPMSM is one of the dangerous failure mode that can result in serious accidents in safety critical applications

The amplitude of the circulating current due to a stator turn fault has a close relationship with the amplitude of the machine terminal voltages

A proper adjustment of the machine terminal voltage can reduce the circulating current significantly; consequently can prevent the complete loss of the faulty machine

The proposed strategy is very effective in safety critical applications, especially in applications where a limp-operation can prevent serious accidents due to an abrupt interruption of an electric motor drive


Future Work

Validation of the Proposed Strategy via Experiments Enhancing the Proposed Strategy by

Considering non-linearity in the magnetic system

Providing machine design guideline for maximizing the

effectiveness of the proposed strategy

Developing a Turn Fault Detection Scheme for IPMSM Drives

Investigation of the Thermal Behaviors of Stator Turn Fault with a Thermal Model


Consideration on Non-Linearity of the Magnetic System

Two main sources of non-linearity : Magnetic saturation and Cross-coupling effects

Approaches for Including Non-linearity in a Machine Model : FEA and

Physical Experiments

Flux Equations with considering cross-coupling effects

,

,

e e eq q q qd d

e e ed d d dq q PM

L i M i

L i M i

Determination of the self- and coupling qd-inductances from the measured qd-flux under various operating conditions by

, ,

, ,

e eq q

q ls mq qde eq d

e ed d

d ls md dqe ed q

L L L Mi i

L L L Mi i

1


By applying the inverse transform from the qd-synchronous rotating reference frame to the abc-stationary reference frame, the phase inductances can be obtained as


2

1 2 1

1 2 1

1 2 1

cos 2 sin 2

4 4cos 2 sin 23 3

2 2cos 2 sin 23 3

( )

( )

( )

aa r ls r r

bb r ls r r

cc r ls r r

L L L L M

L L L L M

L L L L M

Where , , , 1 3md mqL L

L

2 3md mqL L

L

1 3dq qdM M

M

2

3

6

( )dq qdM MM


1 2 1 2

1 2 1 2

1 2 1 2

1 2 1 2

1 2 1

1 2 2cos 2 sin 23 32

1 2 2cos 2 sin 23 32

1 2 2cos 2 sin 23 32

1cos 2 sin 2

2

1 2 2cos 2 sin 23 32

( )

( )

( )

( )

( )

ab r r r

ac r r r

ba r r r

bc r r r

ca r r r

M L L M M

M L L M M

M L L M M

M L L M M

M L L M

2

1 2 1 2

1cos 2 sin 2

2( )cb r r r

M

M L L M M


3

By applying the inverse transform from the qd-synchronous rotating reference frame to the abc-stationary reference frame, the phase inductances can be obtained as


Consideration on Non-Linearity of the Magnetic System Simplified Flux Model from General Profiles of the qd-inductances of

an IPMSM

4

[ ]L H

qL

[ ]Current A

dL

As the negative d-axis current decreases

As the q-axis current increases

,

,

e eq q q

e ed d d PM

L i

L i

0

0

constant,

,

d

qq q

qs

L

LL L

i


In the voltage references, positive- and negative-sequence components will appear

Observation of Voltage References in the Synchronous Rotating Reference Frame

Stator Turn Fault Detection Method

• Blue solid line : Stator voltage vector under fault-free condition• Red dashed line : Positive sequence voltage with stator turn faults• Red long-dashed line: Negative sequence voltage with stator turn faults

qsv_

eqds nomv

dsv

ee

e

_eqds posv

_eqds negv

qdsv_

eqds nomv

_eqds posv

_eqds negv

Time

1

2 e


A stator turn fault generates a hot-spot spreading very fast; therefore, modification of conventional lumped parameter thermal model is required

Thermal Model with Stator Turn Faults

'sP rP

3R

'1R 2R'

1C 2C

S r

a

P RC

RC

SR

P

R

RotorShorted turns Adjacent turns Other healthy turns


A STATOR TURN FAULT TOLERENT STRATEGY

FOR INTERIOR PM SYNCHRONOUS MOTOR

DRIVES in SAFETY CRITICAL APPLICATIONS


Appendices

Further Simulated Waveforms

Simulation under various rotating speeds

Simulation under various fault fractions

Simulation under various loads


Sp

eed

(r

pm

)T

orq

ue

(Nm

)

Waveforms : Rotating Speeds and Developed Torque

(a) Speed reference (dashed red-line) and actual Speed (solid blue-line)

Time (sec)

(b) Torque reference (dashed red-line) and actual torque (solid blue-line)

Time (sec)

Simulation under Various Rotating Speeds 1


Waveforms : Phase Voltage, Line Current, and Fault Current

Time (sec)

Vo

ltag

e (V

)C

urr

ent

(A)

Cu

rren

t (A

)

(a) a-phase line-neutral voltage

(c) Circulating Current in the shorted Turns

(b) a-phase current Time (sec)

Time (sec)

Simulation under Various Rotating Speeds 2


Waveforms : Circulating Currents C

urr

ent

(A)

Time (sec)


1 %

3 %

5 %

Simulation under Various Fault Fractions 1


To

rqu

e (N

m)

Time (sec)

Waveforms : Developed Torques

Developed torque

No fault

1 %

3 %

5 %



Waveforms : Rotating Speeds

Time (sec)

Rotating speed

No fault

1 %

3 %

5 %

Sp

eed

(r

pm

)



Waveforms : Circulating Currents

Time (sec)


No load

40 Nm

80 Nm

Cu

rren

t (A

)

Simulation under Various Loads 1


To

rqu

e (N

m)

Waveforms : Developed Torques

Time (sec)

Developed torque

No load

40 Nm

80 Nm



Waveforms : Rotating Speeds

Time (sec)

Rotating speed

No load

40 Nm

80 Nm

Sp

eed

(r

pm

)


Presented by Youngkook Lee, December 04, 2006 A S TATOR T URN F AULT T OLERENT S TRATEGY FOR I...

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Transcript of Presented by Youngkook Lee, December 04, 2006 A S TATOR T URN F AULT T OLERENT S TRATEGY FOR I...