Prof. Ion BOLDEA
Department of Electrical Machines and Drives, University Politehnica
of Timisoara, V.Parvan 2,
RO - 1900 Timisoara, Romania, Tel.+40-56-204402, E-mail:
boldea@lselinux.utt.ro,
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Contents
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•
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Introduction
Variable speed wind-generator systems
Variable speed hydro-generator systems
Stand-alone variable speed generators
Superhigh speed gas turbine PM generator
systems
• Automotive starter (torque-assist)/alternator
systems
• Home and space electric generator systems
• Conclusion
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Variable speed wind-generator systems
• 13,932 MW by the end of 1999
• 2 – 2.5 MW units
Wind turbine induction generator system with blade angle
control and soft-starter [1]
CR-IG
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Connection circuit for fixed – speed wind turbine
using external resistors
CR-IG
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Measured (gray) and calculated (black)
current magnitude as the 15- kW machine is
connected using external resistance [26]
Measured (gray) and calculated (black) rotor
speed magnitude as the 15- kW machine is
connected using external resistance [26]
Measured (gray) and calculated (black) machine voltage as 15- kW
machine is connected using external resistance [26]
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CR-IG
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Variable speed generator connected to the grid
through bidirectional converter
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CR-IG
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Grid side converter control
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CR-IG
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Machine side converter control
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CR-IG
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CR-IG
 Unity power factor
Phase current and voltage.Speed
1500 rpm, generator, torque 100%
Phase current and voltage per
phase.Speed 1500 rpm, generator,
torque 100%, reactive power 50%
Results with inverter control at power grid
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Stand alone SCIG control systems [3]
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CR-IG
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a) Vdc versus time
b) Vd versus time
Full load application over 50% load application [3]
CR-IG
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Doubly-fed IG (DFIG) wind turbine system
DFIG
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a)
b)
Vector control of DFIG a) and
step active power response b),
without and with decoupled
control [4]
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Sensorless
DFIG with
operating
modes I, II,
III [8]
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Rotor and stator current and their
harmonics content at s = -0.27with
controlled rectifier - current source
inverter in the rotor
DFIG
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DFIG connected to the power grid
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Power [pu / 2000 kW]
Turbine speed referred to generator side [rpm]
Implemented wind turbine characteristics – aerodynamics
characteristics
DFIG
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DFIG
The block diagram of the supply – side converter control [8]
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The block diagram of the machine-side converter control in a
DFIG
doubly-fed wind turbine [8]
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a) The active and b) reactive stator power control [8]
DFIG
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Three-phase short-circuit
on the power grid :
a)
Stator voltage
b) Stator currents
c)
Rotor currents
d) Speed
e)
Turbine torque
f)
Electromagnetic torque
g) Active power
h) Reactive power
[8]
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DFIG
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Modified vector controller
for unbalanced voltages in the
power grid [6]
DFIG
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Stator currents in individual phases
Stator currents in individual phases
for 10% negative-sequence voltage
for 10% negative-sequence voltage
applied - conventional controller [6]
applied - modified controller [6]
DFIG
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Stator currents in individual
phases for two- phase
operation-modified controller
[6]
DFIG
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Sensorless control of DFIG
Im s 
s
 Im s  j Im s
Ls



 s   V s  Rs i s dt

Ls
I  ir  jir   i ms  i s
Lm
s
r
cos  1  ir is
cos  2  ir ? ir
sin 1  ir  ir
sin 2  ir  ? is
sin  er  sin  1   2 
d er
r
dt
DFIG
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Sensorless control of DFIG
Experimental waveforms showing estimated and actual sin  for
step in ifrom
0 to 0.5 p.u. [2]
rq
DFIG
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Sensorless control of DFIG
DFIG
a) Before filtering [2]
b) After filtering
Experimental waveforms showing estimated and actual  at starting
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Variable speed hydrogenerator systems
Pump storage
necessities prompted
by nuclear power
usage led to the
design and
application of two
rather large
(310MW) power
DFIGs; one with a
cycloconverter and
the other with a
GTO inverterconverter in the
rotor circuit [10]
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Ramp power response for motoring mode
(Ohkawachi unit 4) [10]
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DFIG
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Ramp power response for generating mode
(Ohkawachi unit 4) [10]
DFIG
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Goldishtal pump-storage station
300 MW [27]
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DFIG
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Power flow at constant torque in turbine and pump
operation [27]
DFIG
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Stand-alone variable speed generators
Stand-alone MG generator – converter with battery quick back up
PMSG
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PMSG
PM generator advanced mobile genset [28]
PMSG
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PM generator
advanced
mobile genset
[28]
Peak torque,
power and fuel
consumption
PMSG
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PM
alternator
genset
with
Diesel
engine
[28]
PMSG
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Dual stator winding IG with reduced
count inverter – battery system
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CRIG
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Starter generators for vehicular technologies
• Induction type
• IPM brushless type
• Transverse flux PM brushless type
• Switched reluctance type
• Claw pole rotor synchronous type
Characteristics :
* High starting torque
* Large power speed range
* Low volume and system costs
* Low total system losses at 42 Vdc – battery – mild hybrids, 200 –
400 Vdc – battery – full hybrids and electric vehicles
ISG
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Starter-alternators (continued)
So there is the low voltage (42 V d.c.)
starter-alternator and the high voltage (150400 V d.c.) motor-generator for mild and
respective heavy hybrids electric vehicles.
Typical peak torque and voltage versus
speed for a PM-RSM mild hybrid starting
and, respectively, torque-assist mode are
shown in next slide, with corresponding
ISG
efficiency.
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Starter-alternators (continued)
42V
battery
voltage
versus
d.c.
current
load
ISG
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Starteralternators
PM-RSM
crosssection
[12]
ISG
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a) Generating
Rotor position
b) Motoring
 er in relation to  
s
and   s
ISG
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Starter-alternators (continued)
150
1
60
0.9
125
50
100
40
0.8
30
50
20
25
10
Efficiency
75
Voltage (V)
Torque (rpm)
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0
0
1000
2000
3000
speed (rpm)
a)
4000
5000
0
6000
0
0
1000
2000
3000
Speed [rpm]
4000
5000
6000
b)
Peak torque, voltage a) and corresponding machine
efficiency versus speed b) [12]
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ISG
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a)
b)
Potential 42V d.c. automotive starter/alternator system
with winding switch (a.c. machines) and passive
(capacitor) voltage a) and with boost/buck converter b)
ISG
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H-bridge dc – dc boost bidirectional converter with
transformer and inductance (T + L) [11]
ISG
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IGBT losses for the induction motor drive: base
and max speed, with and without boost converter [11]
Total power loss at 30 kW max. delivered power motor
design of Table 2 with boost converter, Vb =180 V [11]
Total power loss at 30 kW max. delivered power motor
design of Table 1 with boost converter, Vb =180 V [11]
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Fundamental rotor – position and speed tracking observer [14]
ISG
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Estimated initial electrical rotor position [14]
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ISG
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Superhigh speed gas turbine PM generator
systems
Typical power – speed ranges :
• to 150 kW at 70 – 80 000 rpm
• to 1.4 – 5 MW at 18 000 – 15 000 rpm
Applications :
Stand alone, standby or cogeneration in distributed
power systems.
PMSG
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The superhigh PM generator : rotors
a) cylindrical
b) disk – shape
PMSG
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Variable speed PMSG system with constant output
voltage and frequency
PMSG
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3 – 5 MW medium voltage superhigh speed PMSG ( f1  0.6  1.2 kHz )
With dc voltage booster and three level PWM inverter
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Home and space electric generator
systems
Stirling
engine
linear PM
generator
[25]
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Various PM linear
alternators [25]
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Conclusion
The present paper leads to conclusions such as:
 variable-speed generator technologies for power
systems are already available up to 400 MW with
doubly-fed induction generator motors. They bring
more flexibility and better efficiency to power
production and transportation for distributed/power
systems wind and hydro electric generators are prime
candidates for variable speed
 better system design optimisation and sensorless
control methodologies are still desired
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• automotive starter-alternator system for mild (42V
d.c.) and heavy (150-600V d.c.) hybrid vehicles have
been proposed in various configurations. The IM
solution has been brought to markets by Toyota and
Honda. Up to 35% fuel consumption reduction in
town driving has been reported for Toyota Prius but
the additional electrical equipment has been rated at
3000 USD. PM-RSM or transverse flux PM rotor
configurations are currently proposed as they are
credited with slightly less initial system costs for
lower total system losses.
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
PM or induction generators with full (respectively
fractionary) power electronics rating are proposed for
dedicated stand alone or mobile gensets in the tens or
hundreds of kW. Faster availability, lower volume and better
energy conversion ratio with faster response for load
transients are expected for such solutions.
• Superhigh speed PM generators with powers up to 150kW
and 75 krpm and for higher powers (up to 5 MW and 15
krpm ) are proposed for distributed power systems, aircraft
and small vessel.
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
Home combined electricity and heat production
through burning natural gas has been demonstrated with
quiet, free piston Stirling engines and linear PM
generators for efficiency above 85%, and at the power
electric grid for tens of thousands of hours in the kW
range. More compact configurations with still high
efficiency and lower initial costs are required to make
home electricity generation truly practical with all
implicit advantages.
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2.
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