February 2, 2004Grainger Center for Electric Machinery and Electromechanics 1 Energy Source...
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Transcript of February 2, 2004Grainger Center for Electric Machinery and Electromechanics 1 Energy Source...
February 2, 2004
Grainger Center for Electric Machinery and Electromechanics1
Energy Source Diversification
Patrick ChapmanAsst. Professor
UIUC
Sponsored by: National Science Foundation
Grainger Center for Electric Machinery and Electromechanics2
What is a diversified energy source?
> 1 energy source Power flow both to and from some sources “Source” may be energy storage Overall ability of multiple sources exceeds the ability of
one alone– reliability– environmental responsibility– adaptability– interchangeability
Grainger Center for Electric Machinery and Electromechanics3
Motivation
Incorporate more ‘preferred’ energy sources– wind– solar– fuel cell
Conversion methods that adapt to various sources and loads– address wide market with single product
Take advantage of deregulation laws
Grainger Center for Electric Machinery and Electromechanics4
Research Areas
Circuit topologies Energy source allocation (static control) Dynamic control Simulation Experimentation
Grainger Center for Electric Machinery and Electromechanics5
Conceptual Diagram
Source-to-load conversions Source-to-source conversions Load-to-source conversions
S o u rc e 3
S o u rc e 2
S o u rc e 1
L o a d 1
L o a d 2
= P o w e r C o n v e rte r s
Grainger Center for Electric Machinery and Electromechanics6
Selected Applications
Classic two-input: Uninterruptable Power Supply
InverterR ec tifie r 110 VA C
Grainger Center for Electric Machinery and Electromechanics7
Solar/Battery
Provide average AC power from solar only
Inverter 110 VA CSolar B oos t
Grainger Center for Electric Machinery and Electromechanics8
Solar/Battery; Flexible Bus Voltage
Allows more flexibility in battery management
Inverter 110 VA CSolar B oos t
B id irec t.dc-dc
Grainger Center for Electric Machinery and Electromechanics9
Fuel Cell / Battery
Provides dynamic capability to fuel cell system
Inverter 110 VA CB oost
B id irec t.dc-dc
F.C .
Grainger Center for Electric Machinery and Electromechanics10
Three-Source Systems
AC Line, Fuel Cell, Battery– (plus capacitor)
Inverter 110 VA CB oost
B id irec t.dc-dc
F.C .
R ec t,PFC )
Grainger Center for Electric Machinery and Electromechanics11
Multiplicity of Same Source
Unbalanced sources, alternative locations
Inverte r 110 VA C
Solar B oos t
So lar B oos t
So lar B oos t
Grainger Center for Electric Machinery and Electromechanics12
Restricted Switch Types
More general switch schematic symbols Forward-conducting, bidirectional-blocking
(FCBB):
GTO, some cases SCR, MOSFET-diode, IGBT-diode, MCT,RB-IGBT (new)
Grainger Center for Electric Machinery and Electromechanics13
Circuit Topologies
Straightforward approaches– “n” sources, “n” converters (or similar)– dc link– ac link
New topologies– “n” sources, “1” converter (with “n” inputs)– embed sources in the converter
Grainger Center for Electric Machinery and Electromechanics14
Standard DC Link
Essentially rectifier-inverter circuit– only we attach different sources and loads
D C /D C
A C /D CD C /A C
D C /D C
D CA C L oad
L oad
Grainger Center for Electric Machinery and Electromechanics15
DC Link with ‘Phase Leg’ Approach
Model after standard bridge inverters, active rectifiers– requires inductive load/source impedance (not
shown)
In 1 In 2 In 3In M
O ut 1 O ut 2 O ut 3O ut N
Grainger Center for Electric Machinery and Electromechanics16
AC Link
Use transformer, coupled inductors– isolation possible– less scalable
D C /A C
A C /A C
A C /A C
A C /D C
D C
A C L oad
L oad
Grainger Center for Electric Machinery and Electromechanics17
Prior Work
First ‘multiple-input’ converter from Matsuo, et al, c. 1990
‘Multiple input’ can be interpreted more broadly– e.g. three-phase rectifier has three inputs
Here, consider the narrow interpretation– three inputs could handle three different sources
(but doesn’t have to)
Grainger Center for Electric Machinery and Electromechanics18
Matsuo’s Circuit
An AC link topology Used in
– solar/battery– wind/solar/utility
Shown experimentally
Dynamic AnalysisIN
-V
+o u t2
-V
+o u t1
V N (to load 2 )
(to load 1 )
N P N
N 1
N 2
I 2
V 2
N P 2
I 1
V 1
N P 1
.
.
.
.
.
.
Grainger Center for Electric Machinery and Electromechanics19
Caricchi’s circuit
Caricchi, et al, developed DC link version, c. 2001
Shown in– hybrid automobile– wind/solar/utility
Can be used with fewer switches
– depends on directionality of sources, loads
Boost only from source to cap.
Buck only from cap. to load
. . . . .V 1 V 2
I 2I 1+
V-o u t
Grainger Center for Electric Machinery and Electromechanics20
DC Link Circuit
Uses one inductor for each load, source– or requires load, source to have inductive series
impedance
Essentially the standard phase legs we know well, applied to multi-source
Uses capacitive energy storage– could be battery instead, but high voltage
Grainger Center for Electric Machinery and Electromechanics21
Buck-Derived Two-Input
Ordinary buck topology– diode cathode goes to a second source, not ground
Sebastian, et al, showed high efficiency attainable– diversification not studied.
I o u t
+V
-o u t
V 1
V 2
Grainger Center for Electric Machinery and Electromechanics22
Multiple-Input Buck
Standard buck with parallel inputs Originally shown by Rodriguez, et al, with only
two inputs– shown with solar/battery
I o u t
I 2
I 1
+V
-o u t
V 1
V 2
Grainger Center for Electric Machinery and Electromechanics23
New, Recent Work at UIUC
Multiple-input buck-boost (MIBB)
I o u t
IN
I 2
I 1
I L
-V+
o u t
V 1
V 2
V N
Grainger Center for Electric Machinery and Electromechanics24
MIBB Characteristics
Buck and boost operation Similar, but simpler, than Matsuo’s approach Scalable to n inputs Can regulate output voltage with an prescribed power
flow from each input (in theory) Probably has some niche in energy source
diversification field In base form, only accommodates unidirectional
source/load– can modify a bit to get bidirectional
Grainger Center for Electric Machinery and Electromechanics25
Cousins of the MIBB
Multiple-input flyback– add isolation, turns ratio
I o u t
IN
I 2
I 1
I L
-V+
o u t
V 1
V 2
V N
N NP 1:
Grainger Center for Electric Machinery and Electromechanics26
Multiple-Input, Multiple-Output
Flyback with multiple, isolated outputs
IN
I 2
I 1
-V+
o u t2
-V+
o u t1
V 1
V 2
V N
(to load 2 )
(to load 1 )
N P
N 1
N 2
Grainger Center for Electric Machinery and Electromechanics27
Multiple Output, Some Isolated
IN
I 2
I 1
I L
-V
+o u t2
-V
+o u t1
V 1
V 2
V N
N P :N 1
Grainger Center for Electric Machinery and Electromechanics28
With a bidirectional load/source
Battery load/source concept
I o u t
IN
I2
I1
-V+
o u t
V 1
V 2
V N
(to load)
(batte ry - a sourceor load)
unid
irec
tiona
lso
urce
s
Grainger Center for Electric Machinery and Electromechanics29
MIBB with Multiplicity of Sources
Battery balancer– (other, probably better balancers exist…)
IN
I 2
I 1
I L
N P :N 1
c e ll 1
c e ll 2
B a tte ryP a c k
c e ll N
c e ll 1N +
Grainger Center for Electric Machinery and Electromechanics30
Steady-State Analysis
Many switching strategies possible– first attempts involve simple common-edge,
constant frequency, approach
0
1q N
q 2
q 1
T
D T1
D T2
D TN
Grainger Center for Electric Machinery and Electromechanics31
Steady-State Analysis, cont’d
Begin with basic MIBB, continuous mode The instantaneous inductor voltage
Setting the average to zero, solving for Vout:
maxL i i out ii
v qV V q
0
0
maxT
i ii
out T
ii
qV dtV
q dt
1 max
ieff ii
outi
i
D VV
D
Grainger Center for Electric Machinery and Electromechanics32
Effective Duty Cycle
The effective duty cycle is the time a switch conducts nonzero current
Can be shown:
1
1
1 1
1 1
0,
,
i
i eff jj
eff i i i
i ieff j eff jj j
D D
D
D D D D
Grainger Center for Electric Machinery and Electromechanics33
Two-Input Case
V1 > V2, D1 > D2– normal buck-boost, single input
V1 > V2, D2 > D1
11
11out
DV V
D
1 1 2 1 2
21out
DV D D VV
D
Grainger Center for Electric Machinery and Electromechanics34
Selecting Duty Cycles
Given prescribed:– Power, Pi, for each source
– Output Voltage, Vout– Input Voltages, Vi
**
** *
1iouteff i
jiout j
j jj
PD V
PVV P
V
Grainger Center for Electric Machinery and Electromechanics35
Plausibility of Duty Cycles
Sum of all effective duty cycles less than one?
YES, since: May be issues with extreme duty cycles
– same for all converters
1 ?eff jj
D
**
** *
1 ?jout
jj jout j
j jj
PV
P VV P
V
* 0jj
P
Grainger Center for Electric Machinery and Electromechanics36
Correcting for Nonideal
Simple switch-drop model More complicated models possible Feedback to cancel nonidealities
Grainger Center for Electric Machinery and Electromechanics37
Experimental Continuous Mode
Vary one duty cycle of three Hold all other constant, constant R load
25 35 45 55 65D 1 (% )
30
40
50
60
V o ut (V )M easuredIdea lC ons tan t-D rop
Grainger Center for Electric Machinery and Electromechanics38
Discontinuous Mode
Inductor current is zero for some portion of each cycle
p j jeff jj j
Ti i D V
L
| |i jiL
t do n
T
D Tef f j( )
Grainger Center for Electric Machinery and Electromechanics39
Average Output Voltage
Energy balance
Output Voltage– similar to standard buck-boost
21
2 p out out out out donLi CV v V I t
2out p
RLV i
T
Grainger Center for Electric Machinery and Electromechanics40
Characteristics of Discontinuous Mode
Very sensitive to parameters– feedback a must
Improve accuracy by including– switch drop model– core loss model
taken from Micrometals data sheets iterative procedure with switch-drop model as starting point
Grainger Center for Electric Machinery and Electromechanics41
Experimental, Discontinuous
Vary one duty cycle, hold others constant
M easuredIdea lSw itch-d ropSw itch-d rop + co re loss
20
30
40
50
30 40 50 60 70
V o ut (V )
D 3 (% )
Grainger Center for Electric Machinery and Electromechanics42
Other Work at UIUC
Multiple-input flyback– currently being investigated– successful simulation, analysis
Multiple-input boost– n boost converters with common output capacitor– power from unlike solar array sources– simulation, design stage
Grainger Center for Electric Machinery and Electromechanics43
Work to be Done
Dynamic analysis Dynamic control
– case-by-case? Static control
– power management– case-by-case
Evaluation of topologies Interchangeable sources Topology restructuring