Performance Enhancements using Matrix Converters in Open-Ended Drives Ned Mohan Krushna Mohapatra
University of Minnesota
Thursday March 1, 2007 APEC 2007
Copyright 2007
1
U.S. Energy Production and Consumption
(a)
(b)
Fig. 3-1 Production and consumption of energy in the United States in 2004 [1].
Lighting 19%
• Motors Consume
IT 14%
Copyright HVAC 2007
~2/3rd of the Electricity 16%
Motors 51%
2
Role of Power Electronics Power Electronics Interface Converter Source
Load Controller
Figure 1-1 Power electronics interface between the source and the load. Electric Drive
fixed form
Power Processing Unit (PPU)
Motor speed / position
adjustable form
Electric Source (utility)
Load
Sensors measured speed/ position
Controller
Power Signal
input command (speed / position)
Power Electronics has set free the electroCopyright 2007 mechanical systems!
3
Power Electronic Systems - Voltage-Link conv1
conv2
utility
Load
controller
12 uni-directional switches
Figure 1-19 Load-side converter in a voltage-source structure.
Problems with the Storage Capacitor: 1. Weight and cost 2. Reliability 3. Inrush Current at switch-on 4. Not suitable for high temperature operation 5. Difficult to integrate Motor and the Power Electronics
Problem of Bearing Currents
Copyright 2007
4
Matrix Converters AC Source
AC Machine
• Direct-Link (no energy storage) • Limitation of 86.7% Voltage Output • 18 uni-directional switches • Ideal with SiC Devices
Copyright 2007
5
Shortcomings of Single Matrix Converters
Only 86.7% Voltage: REMOVED Common-Mode Voltage (Bearing Currents): Eliminated Large Number of Switches: Increased Control Complexity : Simplified?
Copyright 2007
6
Open-Ended AC Drives without Intermediate Energy Storage Proposed Topology and Control
Solid-State Switches and wires (no capacitor or inductor)
first set of multi-phase voltages
Open-Ended Motor or Generator
Power (motoring mode) Power (generating mode)
Copyright 2007
Patent Application filed by the University of Minnesota
7
Open-Ended AC Drives with Matrix Converters
MC2
MC1
MC ≡ Matrix Converter
Copyright 2007
Open-Ended AC Motor
Patent Application filed by the University of Minnesota
8
Conventional Voltage-Link System Vph,in
+ Vph, m = Vph,in −
+ Vd
− Vd = VˆLL,in
Vins = VˆLL,in
Open-Ended Machine Supplied by Two Matrix Converters V ph , in
V ph , m = 1.5V ph , in + − MC1
MC2 insulation
Copyright 2007
Vins = Vˆph , in
Vins = Vˆph , in
9
Capability Curves with Common Mode Voltages Eliminated proposed Tem =1 pu
conventional Vm =1.5 pu
proposed
Vm =1.0 pu
conventional
0
Copyright 2007
0.5pu
1.0pu
1.5pu
ωm, f
10
Simultaneous Benefits Increases available voltage to 150%
1.
• • 2. 3. 4. 5. 6.
7.
rated torque up to 150% of the rated speed 150% power output capability
Bearing currents are eliminated Slot insulation reduced by a factor 1.73 Comparable efficiency Input power factor is controllable Elimination of Bulky Energy Storage Capacitors with inrush current problem Increased Reliability
Copyright 2007
11
Reduced Switch Topology
Patent Application filed by the University of Minnesota
Reliability; Reduced Switching Losses
Copyright 2007
Patent Application filed by the University of Minnesota
12
Can be Applied in the Rotor Circuit of Doubly-Fed Induction Generators For Windmills Wound rotor Induction Generator
AC Wind Turbine
DC DC
Generator-side Converter
AC Grid-side Converter
Fig. 3-10 Doubly-fed, wound-rotor induction generator [9]. Patent Application filed by the University of Minnesota
Copyright 2007
13
Proposed System Operation iA
ia
A
a ib b ic
MC1
c
r v s = v a e j 0 + vb e j 2 π / 3 + v c e j 4 π / 3 r is = ia e j 0 + ib e j 2π / 3 + ic e j 4π / 3
iB
A′
B′
B
iC C
a
MC2
C′
b c
r v0 = v A e j 0 + vB e j 2π / 3 + vC e j 4π / 3 r v0′ = − ( v A′e j 0 + vB ′e j 2π / 3 + vC ′e j 4π / 3 )
r r r vm = v0 + v0′ r im = i Ae j 0 + iB e j 2π / 3 + iC e j 4π / 3 Copyright 2007
14
CCW Basic Vectors:
A
B
C
(no common-mode)
a
b
c
c
a
b
b
c
a
r vm (2)
B − phase
B − phase
r v0 ( cab)
r vm (3)
r v0′ (bca )
B − phase
r vm (1) 3 pu
A − phase
r v0 ( abc)
A − phase
Copyright 2007
1 pu
r v0′ ( cab)
r v0 (bca ) C − phase
A − phase
r v0′ ( abc)
r vm (6)
r vm (4) C − phase
C − phase
Three zero-vectors
r vm (5)
15
Maximum Output using CCW Basic Vectors: (no common-mode)
A
B
C
a
b
c
c
a
b
b
c
a
Open-ended Machine; Matrix Converter ron each side
Single Matrix Converter
vm (2)
B − phase
r vm (3)
B − phase Vˆ0,max = 1.5
r v0 ( cab)
Vˆ0,max = 0.5
3 pu r vm (1)
A − phase
A − phase
r v0 ( abc ) = 1.0
r v0 (bca )
r vm (4)
r vm (6)
C − phase
C − phase
Copyright 2007
r vm (5)
16
CW Basic Vectors:
A
B
C
(no common-mode)
a
c
b
b
a
c
c
b
a
r vm (2)
B − phase
B − phase
r v0 (bac )
r vm (3)
r v0′ ( cba )
A − phase
r v0 ( acb)
Copyright 2007
r vm (1)
A − phase
A − phase
r v0′ ( acb)
r v0′ (bac )
r v0 ( cba ) C − phase
B − phase
r vm (6)
r vm (4) C − phase
C − phase
Three zero-vectors
r vm (5)
17
Relationship Between Output Voltage Vectors and Input Current Vectors: CCW Basic Vectors: (no common-mode) i Output Voltages Input Currents i A
a
B
b
A
B
C
a
b
c
a
b
c
A
B
C
A
B
c
C
iC
a
A
iA
B
iB
b
c
a
b
B
C
A
c
C
iC
b
c
a
C
A
B
a
A
iA
B
iB
C
iC
B − phase
r v0 (cab) r is (CAB)
b
c
A− phase
r v0 (abc) r is ( ABC)
Copyright 2007
r v0 (bca) r is (BCA)
18 C − phase
Relationship Between Output Voltage Vectors and Input Current Vectors: CW Basic Vectors: (no common-mode) Output Voltages Input Currents A
iA
B
iB
c
C
iC
a
A
iA
B
iB
c
C
iC
a
A
iA
B
iB
C
iC
a
A a
B c
C b
a A
b C
c B
b
a
c
B
A
C
c
b
a
C
B
A
B − phase
r v0 (bac) r is (BAC)
b
b
b
c
A − phase
r v0 (acb) r is ( ACB)
Copyright 2007
r v0 (cba) r is (CBA)
C − phase
19
Input Power Factor Control Example
Unity PF Input in a MC without Common-Mode Voltages: a
A
b
B
MC
c
C
phase − B
phase − B
r vr0 (bac) is ( BAC )
r vr0 (bca ) is (CAB )
r v0 r is , CW r i0
r v0
r i0
r vr0 ( abc) is ( ABC ) phase − A r vs
phase − C
Copyright 2007
r v0 r i0 r is
phase − A
r vs
r is , CCW
r is , CCW
r vr0 ( cab) is ( BCA)
r vr0 ( acb) is ( ACB ) r vs
r is , CW
r vr0 ( cba ) is (CBA) phase − C
20
Slot Insulation
vcond
Conventional Voltage-Link System + V ph , m = V ph , in − V ph , in
Under Zero-VoltageState: VN = 0
+ Vd
−
∴ Vins = VˆLL , in
N
Vd = VˆLL , in
Vins = VˆLL , in
Proposed System: Open-Ended Machine Supplied by a MC from Each Side V ph , in
V (conventional) ∴ Vins = Vˆph ,in = ins 3
V ph , m = 1.5V ph , in + − MC1
Copyright 2007
Vins = Vˆph , in
MC2 Vins = Vˆph , in
21
Elimination of Storage Capacitor Conventional Voltage-Link System + V ph , m = V ph , in −
V ph , in
Proposed System V ph , in
+ Vd − Vd = VˆLL , in
V ph , m = 1.5V ph , in + −
Vins = VˆLL , in MC1
MC2
N Vins = Vˆph , in
Vins = Vˆph , in
Problems with the Storage Capacitor: 1. Weight and cost 2. Reliability 3. Inrush Current at switch-on 4. Additional currents under input unbalance 5. Difficult to integrate motor and the inverter Copyright 2007
22
Simulation Results: Output Voltages and Currents
Fig .9b
Copyright 2007
The output phase voltage averaged over every switch cycle and the output current.
23
Simulation Results: Input Voltages and Currents
Fig .9c
Copyright 2007
The input phase voltage and the input phase current.
24
Power Semiconductor Price Trends
0.7
USD/A 1200 V IGBTs
0.6 0.5 0.4 0.3 0.2 0.1 0
1990
1995
2000
2005
Copper and Steel Prices - Copper prices have gone up five fold in three years
Copyright 2007
25
Advantages of SiC Devices - Closer to an ideal switch - Lower Losses; Higher Efficiency - High Temperature; Compact Design
Copyright 2007
26
Applications
Anywhere motors/generators connected through power electronics, for example any
variable-speed motor drive for military or civilian application harnessing of wind energy by wind turbines
Ideally suited for SiC devices Lighting 19%
• Motors consume 2/3rd of the electricity generated IT 14%
HVAC 16%
Copyright 2007
• Many generators could be connected through power electronics Motors 51%
27
Wind Resource in the U.S.
Fig. 3-7 Wind-resource map of the United States [6].
20% of the U.S. Power Production can be by Wind Copyright 2007
28