Transcript February 2004 - CEME Logo Research Projects by Area

Energy Source Diversification
Patrick Chapman
Asst. Professor
UIUC
Sponsored by: National
Science Foundation
1
February 2, 2004
Grainger Center for Electric Machinery
and Electromechanics
What is a diversified energy
source?
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> 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
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reliability
environmental responsibility
adaptability
interchangeability
Grainger Center for Electric Machinery and Electromechanics
Motivation
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Incorporate more ‘preferred’ energy sources
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–
–
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Conversion methods that adapt to various
sources and loads
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3
wind
solar
fuel cell
address wide market with single product
Take advantage of deregulation laws
Grainger Center for Electric Machinery and Electromechanics
Research Areas
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Circuit topologies
Energy source allocation (static control)
Dynamic control
Simulation
Experimentation
Grainger Center for Electric Machinery and Electromechanics
Conceptual Diagram
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
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Source-to-load conversions
Source-to-source conversions
Load-to-source conversions
Source 1
Load 1
= Power Converters
Source 2
Load 2
Source 3
5
Grainger Center for Electric Machinery and Electromechanics
Selected Applications

Classic two-input: Uninterruptable Power
Supply
Rectifier
6
Inverter
110 VAC
Grainger Center for Electric Machinery and Electromechanics
Solar/Battery

Provide average AC power from solar only
Solar
7
Boost
Inverter
110 VAC
Grainger Center for Electric Machinery and Electromechanics
Solar/Battery; Flexible Bus Voltage

Allows more flexibility in battery management
Solar
Boost
Inverter
110 VAC
Bidirect.
dc-dc
8
Grainger Center for Electric Machinery and Electromechanics
Fuel Cell / Battery

Provides dynamic capability to fuel cell system
F.C.
Boost
Inverter
110 VAC
Bidirect.
dc-dc
9
Grainger Center for Electric Machinery and Electromechanics
Three-Source Systems

AC Line, Fuel Cell, Battery
–
(plus capacitor)
Rect,
PFC)
F.C.
Boost
Inverter
110 VAC
Bidirect.
dc-dc
10
Grainger Center for Electric Machinery and Electromechanics
Multiplicity of Same Source

11
Unbalanced sources, alternative locations
Solar
Boost
Solar
Boost
Solar
Boost
Inverter
110 VAC
Grainger Center for Electric Machinery and Electromechanics
Restricted Switch Types
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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 Electromechanics
Circuit Topologies
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Straightforward approaches
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New topologies
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“n” sources, “n” converters (or similar)
dc link
ac link
“n” sources, “1” converter (with “n” inputs)
embed sources in the converter
Grainger Center for Electric Machinery and Electromechanics
Standard DC Link

Essentially rectifier-inverter circuit
–
only we attach different sources and loads
AC/DC
DC/DC
DC/DC
AC
DC
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DC/AC
Load
Load
Grainger Center for Electric Machinery and Electromechanics
DC Link with ‘Phase Leg’ Approach

Model after standard bridge inverters, active
rectifiers
–
In 1
15
requires inductive load/source impedance (not
shown)
In 2
In 3
Out 1
In M
Out N
Out 2
Out 3
Grainger Center for Electric Machinery and Electromechanics
AC Link

Use transformer, coupled inductors
–
–
isolation possible
less scalable
AC/AC
AC/DC
Load
AC
DC/AC
DC
16
AC/AC
Load
Grainger Center for Electric Machinery and Electromechanics
Prior Work
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
First ‘multiple-input’ converter from Matsuo, et
al, c. 1990
‘Multiple input’ can be interpreted more broadly
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Here, consider the narrow interpretation
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e.g. three-phase rectifier has three inputs
three inputs could handle three different sources
(but doesn’t have to)
Grainger Center for Electric Machinery and Electromechanics
Matsuo’s Circuit
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An AC link topology
Used in
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solar/battery
wind/solar/utility
Shown
experimentally
Dynamic Analysis
I1
V1
NP1
.
.
.
I2
V2
NP2
IN
.
.
.
N1
VN
NPN
N2
- (to load 1)
Vout1
+
- (to load 2)
Vout2
+
Grainger Center for Electric Machinery and Electromechanics
Caricchi’s circuit
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
Caricchi, et al, developed
DC link version, c. 2001
Shown in
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–
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Can be used with fewer
switches
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hybrid automobile
wind/solar/utility
V1 I1
V2
I2
.....
+
Vout
-
depends on directionality
of sources, loads
Boost only from source to
cap.
Buck only from cap. to
load
Grainger Center for Electric Machinery and Electromechanics
DC Link Circuit
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Uses one inductor for each load, source
–
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Essentially the standard phase legs we know
well, applied to multi-source
Uses capacitive energy storage
–
20
or requires load, source to have inductive series
impedance
could be battery instead, but high voltage
Grainger Center for Electric Machinery and Electromechanics
Buck-Derived Two-Input

Ordinary buck topology
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diode cathode goes to a second source, not ground
Sebastian, et al, showed high efficiency
attainable
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diversification not studied.
Iout
V1
V2
21
+
Vout
Grainger Center for Electric Machinery and Electromechanics
Multiple-Input Buck
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Standard buck with parallel inputs
Originally shown by Rodriguez, et al, with only
two inputs
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shown with solar/battery
I2
V2
V1
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I1
Iout
+
Vout
Grainger Center for Electric Machinery and Electromechanics
New, Recent Work at UIUC
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Multiple-input buck-boost (MIBB)
IN
VN
I2
V2
Iout
I1
V1
IL
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Vout
+
Grainger Center for Electric Machinery and Electromechanics
MIBB Characteristics
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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
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can modify a bit to get bidirectional
Grainger Center for Electric Machinery and Electromechanics
Cousins of the MIBB
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Multiple-input flyback
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add isolation, turns ratio
IN
VN
I2
V2
I1
NP:N1
V1
IL
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Iout
Vout
+
Grainger Center for Electric Machinery and Electromechanics
Multiple-Input, Multiple-Output
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Flyback with multiple, isolated outputs
VN
IN
N1
I2
V2
I1
V1
NP
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- (to load 1)
Vout1
+
N2
- (to load 2)
Vout2
+
Grainger Center for Electric Machinery and Electromechanics
Multiple Output, Some Isolated
Vout1
+
IN
VN
I2
V2
I1
NP:N1
V1
IL
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Vout2
+
Grainger Center for Electric Machinery and Electromechanics
With a bidirectional load/source
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Battery load/source concept
IN
unidirectional
sources
VN
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V2
V1
I2
(battery- a source
or load)
I1
Iout
- (to load)
Vout
+
Grainger Center for Electric Machinery and Electromechanics
MIBB with Multiplicity of Sources
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Battery balancer
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(other, probably better balancers exist…)
cell
N +1
cell
N
cell 2
cell 1
IN
I2
I1
NP:N1
IL
Battery
Pack
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Grainger Center for Electric Machinery and Electromechanics
Steady-State Analysis
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Many switching strategies possible
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first attempts involve simple common-edge,
constant frequency, approach
qN 1
0
DNT
q2
D2T
q1
D1T
T
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Grainger Center for Electric Machinery and Electromechanics
Steady-State Analysis, cont’d
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Begin with basic MIBB, continuous mode
The instantaneous inductor voltage
vL  max  qiVi   Vout  qi
i
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Setting the average to zero, solving for Vout:
Vout


T
0
max  qiVi  dt
i
T
  q dt
0
i
i
Vout 
D
V
eff  i  i
i
1  max  Di 
i
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Grainger Center for Electric Machinery and Electromechanics
Effective Duty Cycle
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The effective duty cycle is the time a switch
conducts nonzero current
Can be shown:
Deff i 
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i 1

Di   Deff  j 
0,
j 1


i 1
i 1
D  D
, Di   Deff  j 
eff  j 
 i 
j 1
j 1
Grainger Center for Electric Machinery and Electromechanics
Two-Input Case
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V1 > V2, D1 > D2
–
normal buck-boost, single input
Vout 
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V1 > V2, D2 > D1
Vout
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D1
V1
1  D1
DV
1 1   D2  D1  V2

1  D2
Grainger Center for Electric Machinery and Electromechanics
Selecting Duty Cycles

Given prescribed:
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Power, Pi, for each source
Output Voltage, Vout
Input Voltages, Vi
Deff i   V
*
out
Pi *
Vi
*
Vout

j
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1
Pj*
Vj
  Pj*
j
Grainger Center for Electric Machinery and Electromechanics
Plausibility of Duty Cycles
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Sum of all effective duty cycles less than one?
j Deff  j   1  ? 
*
Pj*
Vout
j V  1
*
P
*
Vout
j Vj  j Pj* j
j
 ?
*
P
 YES, since:  j  0

j
May be issues with extreme duty cycles
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same for all converters
Grainger Center for Electric Machinery and Electromechanics
Correcting for Nonideal
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Simple switch-drop model
More complicated models possible
Feedback to cancel nonidealities
Grainger Center for Electric Machinery and Electromechanics
Experimental Continuous Mode
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Vary one duty cycle of three
Hold all other constant, constant R load
60
Vout (V)
Measured
Ideal
Constant-Drop
50
40
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30
25
35
45
D1 (%)
55
65
Grainger Center for Electric Machinery and Electromechanics
Discontinuous Mode
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Inductor current is zero for some portion of
each cycle
T
i p   i j   Deff  j V j
L j
j
iL
|ij|
tdon
Deff(j)T
T
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Grainger Center for Electric Machinery and Electromechanics
Average Output Voltage
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Energy balance
1 2
Li p  CVout vout  Vout I out tdon
2
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Output Voltage
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similar to standard buck-boost
Vout  i p
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RL
2T
Grainger Center for Electric Machinery and Electromechanics
Characteristics of Discontinuous
Mode
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Very sensitive to parameters
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feedback a must
Improve accuracy by including
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switch drop model
core loss model
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taken from Micrometals data sheets
iterative procedure with switch-drop model as starting point
Grainger Center for Electric Machinery and Electromechanics
Experimental, Discontinuous

Vary one duty cycle, hold others constant
Measured
Ideal
Switch-drop
Switch-drop + core loss
50
Vout (V)
40
30
20
30
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40
50
D3 (%)
60
70
Grainger Center for Electric Machinery and Electromechanics
Other Work at UIUC
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Multiple-input flyback
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Multiple-input boost
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currently being investigated
successful simulation, analysis
n boost converters with common output capacitor
power from unlike solar array sources
simulation, design stage
Grainger Center for Electric Machinery and Electromechanics
Work to be Done
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Dynamic analysis
Dynamic control
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Static control
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case-by-case?
power management
case-by-case
Evaluation of topologies
Interchangeable sources
Topology restructuring
Grainger Center for Electric Machinery and Electromechanics