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CPES Webinar 20210105 Feng Jin Final

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CPES Webinar
The Bradley Department of Electrical and Computer Engineering
College of Engineering
Virginia Tech, Blacksburg, Virginia, USA
High-Efficiency High-Density DC/DC Converter for
Battery Charger Applications
Feng Jin, Chen Chen, Dr. Qiang Li, Dr. Fred C. Lee
Sponsored By
Jan. 13th, 2020
Electric Vehicle Charger
EV Advantages
• Eco-friendliness
• Low greenhouse gas emission
• Economical solution in a long run
Battery Pack
On Board Charger
Off Board Charger
(fast charger)
EV
Battery Pack Solutions in EV
Battery Capacity:
Battery volt./Range:
Battery Capacity:
Battery volt./Range:
VW E-Golf
Nissan Leaf
Chevrolet Bolt
Spring 2019
35.8KWH
323 V,125 Mi
Spring 2019
62 kWH
360V,226 Mi
Aug. 2019
66 kWH
350V,238 Mi
TESLA Model X/S/3
Mercedes EQC
PORSCHE Taycan
Sep. 2015
100KWH
400V, 351 Mi
Fall 2019
80kWH
405V, 220 Mi
2020
93kWH
800V, 201 Mi
Trend: 1. Larger Battery 2. Higher
Charging Time Comparison
Battery Pack:
TESLA Model X
100KWH/400V
Charging Options
On-Board Charger:
Up to 11.5 kW
~10h
0
[Ref] https://www.tesla.com/support/home-charging-installation/wall-connector
[Ref] https://www.tesla.com/blog/introducing-v3-supercharging
Fast Charging
~0.5h
Off-Board Charger:
Up to 250kW
2
4
6
8
10 t/hour
State-of-the-art Fast Charging
Input volt.:
Power:
Output volt.:
Eff.:
TESLA
SIEMENS
ABB
480VAC
250kW
50-480VDC
92% – 94%
400VAC
150kW
200-920V
94%
480VAC
175/350/500kW
150-920VDC
95%
Chargepoint
400/480VAC
500kW
200-1000V
95%
EV Charger from 3 Phase AC Bus
MVAC
Neutral
3Φ-Grid
480VAC
AC/DC
PFC Stage
AC/DC
PFC Stage
AC/DC
PFC Stage
DC Bus
DC Bus
DC Bus
DC/DC
Isolation
DC/DC
Isolation
DC/DC
Isolation
200~450V
200~450V
400~800V
Ronanki,
D.; Kelkar, A.; Williamson, S.S. Extreme Fast Charging Technology—Prospects
to Enhance
Sustainable Electric Transportation. Energies 2019, 12, 3721.
1/5/2021
Center for Power Electronics
Systems
6
EV Charger From DC Bus
C
B
A
Filter &
protection
MVAC
DC bus
…
Modular Design
~ = =
~ ==
=
~ = = ===
~ =
~ =
=
~ == =
=
=
~ ×n= =
~ ==
=
=
~ =
Neutral
=
=
SST
3Φ-Grid
AC/DC
PFC Stage
DC/DC
Isolation
PV or other
renewable
energy
Energy
Battery
DC/DC
Isolation
DC/DC
Isolation
DC/DC
Isolation
200~450V
400~800V
DC bus
S., Zhao, High Frequency Isolated Power Conversion from Medium Voltage AC to Low Voltage DC. MS defense, 2016.
Ronanki,
D.; Kelkar, A.; Williamson, S.S. Extreme Fast Charging Technology—Prospects
to Enhance
Sustainable Electric Transportation. Energies 2019, 12, 3721.
1/5/2021
Center for Power Electronics
Systems
7
Modular Approach for Fast Charger
135kW Super Charger
11.5kW Module
3.8kW Power Stage
3.8kW Power Stage
3.8kW Power Stage
11.5kW Module
11.5kW Module
11.5kW Module
12 Module
11.5kW Module
Modular approach is good solution to achieve fast charging.
1/5/2021
Center for Power Electronics Systems
8
Universal Charging DC/DC Module
DC bus
DC/DC
Isolation
DC/DC
Isolation
DC/DC
Isolation
200~400V
200~400V
400~800V
Requirements for DC/DC Isolation Converter:
1. Wide output voltage capability (200 V to 800 V)
2. Modular Design
3. Bidirectional energy transfer
4. Design for Automation
5. High Efficiency and High Power Density
High Efficiency High Density DC/DC Module with wide output voltage range is necessary.
850V
Proposed DC/DC Solution
Interleaved
Buck
3 Phase CLLC
850V
**
**
**
**
**
**
**
**
**
**
**
**
οƒ˜ Interleaved Buck to cover wide output voltage range
οƒ˜ Modular design
οƒ˜ Bi-directional energy transfer
οƒ˜ Integrated PCB Winding Transformers and Inductor.
200V~
800V
Magnetic Integration for One Phase
Inductor
Inductor
**
Two Transformers
3P3S
3P3S
**
Transformer
**
**
Bulky and high cost!
4P2S
3P3S
**
**
2 transformers in 1 core
πœ±πœ±π’Œπ’Œ
2P4S
3P3S
πœ±πœ±π’Žπ’Ž
Two Trans. + Two Indu.
1/5/2021
Center for Power Electronics Systems
11
Integration of 3 Phase CLLC Transformer
4P2S
**
VTIP 17-108
2P4S
**
**
**
**
**
πΏπΏπ‘šπ‘š
16
=
𝑅𝑅𝑔𝑔
4
πΏπΏπ‘˜π‘˜ =
𝑅𝑅𝑔𝑔
πΏπΏπ‘šπ‘š
𝐿𝐿𝑛𝑛 =
=4
πΏπΏπ‘˜π‘˜
Center for Magnetics
Power Electronics
Systems
B. Li, 1/5/2021
dissertation, High Frequency Bi-directional DC/DC Converter with Integrated
for Battery
Charger Application, Virginia Tech Sep., 2018.
12
Flux Density Comparison
Case 1: 6 Layer
3P3S
Case 2: 6 Layer
4P2S
3P3S
Bmax
5P3S
2P4S
Integrate Lk
𝑳𝑳𝒏𝒏 = ∞, π‘³π‘³π’Œπ’Œ = 𝟎𝟎
Case 3: 8 Layer
6 οƒ  8 Turns
𝑳𝑳𝒏𝒏 = πŸ’πŸ’, π‘³π‘³π’Œπ’Œ = πŸ“πŸ“ µπ‘―𝑯
𝑳𝑳𝒏𝒏 = πŸ•πŸ•. πŸ“πŸ“, π‘³π‘³π’Œπ’Œ = 𝟐𝟐. πŸ”πŸ”πŸ”πŸ” µπ‘―𝑯
Vin=850, Vo=850V, fs= 500kHz, Lm = 20µH, Same Core. Based on Maxwell 3D FEA simulation.
1/5/2021
3P5S
Center for Power Electronics Systems
13
Design Steps of Integrated Transformer
1/5/2021
Center for Power Electronics Systems
15
Step 1: PCB Winding Implementation
5P3S
A
3P5S
8-Layer board
configuration
π‘³π‘³π’Žπ’Ž = 𝟐𝟐𝟐𝟐𝟐𝟐𝟐, 𝑳𝑳𝒓𝒓 = 𝟐𝟐. πŸ”πŸ”πŸ”πŸ”π’π’π’π’
5P3S
8-turn Transformer + Shielding
6 Layer Mother Board
+
6 Layer Daughter Board
3P5S
Motherboard
Daughter
Primary Winding
Secondary Winding
Shielding
Step 2: Core Material Selection at 500kHz
10000
500kHz
Pv(kW/m3)
1000
100
ML95S – Hitachi
ML-X6 – Hitachi
3F36 – Ferroxcube
N49 – TDK
DMR51W – DMEGC
10
1
10
100
Bac(mT)
Limitation of
fabrications
Step 3: Define the Shape of Transformer
c
r
r: Radius of the core leg
C: Winding width of the
transformer
Footprint
Step 4: Winding Loss Simulation
• Given:
fs, Lm, Np, Ns
• Design Variables:
r, c
• Method: 2D FEA Simulation
• Excitation: Switching-Cycle Pri./Sec. Current from Simulation
• Winding Loss at One Operating Point:
𝑃𝑃𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀𝑀 = 𝑓𝑓 π‘Ÿπ‘Ÿ, 𝑐𝑐
Step 5: Core Loss Calculation
• Given:
fs, Lm, Np, Ns
• Design Variables:
r, c
• Method: Equivalent Elliptical Loop Calculation
• Excitation: Flux density waveform from Calculation
• Core Loss at One Operating Point:
𝑃𝑃𝑐𝑐𝑐𝑐𝑐𝑐𝑐𝑐 = 𝑃𝑃𝑣𝑣 π‘Ÿπ‘Ÿ, 𝑐𝑐 οΏ½ 𝑉𝑉 π‘Ÿπ‘Ÿ, 𝑐𝑐
Transformer Winding Loss
Vin=850V, Lm=20uH, Lr=2.67uH, Ln=7.5
Winding Loss/W
8
Vin: 850V
Vo: 850V
Po: 12.5kW
Lm=20uH, Lr=2.67uH, Ln=7.5
7
c/mm
6
5
4
3 8
Results are based on EEL Calculation.
9
10
11
r/mm
12
13
14
r: Core Radius, c: Winding Width
Transformer Core Loss
Vin=850V, Lm=20uH, Lr=2.67uH, Ln=7.5
Core Loss/W
8
Vin: 850V
Vo: 850V
Po: 12.5kW
Lm=20uH, Lr=2.67uH, Ln=7.5
7
c/mm
6
5
4
3 8
Results are based on EEL Calculation.
9
10
11
r/mm
12
13
14
r: Core Radius, c: Winding Width
Transformer Total Loss
Vin=850V, Lm=20uH, Lr=2.67uH, Ln=7.5
Footprint --- Total Loss ___
8
7
c/mm
c/mm
6
5
#1
4
3
8
Design #1
Results are based on EEL Calculation.
10
12
14
Winding Loss
Core Loss
Total Loss
40
35
r/mm
75
r: Core Radius, c: Winding Width
Loss Evaluation vs. Footprint
150
6 turn, Ln=4
Total Loss/W
100
Design Point
50
0
5000
Loss Breakdown of 3
Phase CLLC
113.6W
8 turn, Ln=7.5
10 turn, Ln=12
6000
7000 8000 9000
Footprint/mm2
10000 11000
Devices Loss
Vin=850, Vo=850V, fs= 500kHz, Lm = 20µH
1/5/2021
Center for Power Electronics Systems
40W
34W
Trans Core
Loss
Trans Wind.
Loss
24
Waveforms of 3P CLLC @ 100% Load
vds2
400V/div
vSR2
400V/div
isec1
15A/div
ipri1
vds2
vSR2
ipri1
isec1
15A/div
iLm1
15A/div
π‘½π‘½π’Šπ’Šπ’Šπ’Š = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝑽𝑽𝒐𝒐 = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝟏𝟏𝟏𝟏𝟏𝟏𝟏 𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳
iLm1
500ns/div
Waveforms of 3P CLLC @ 100% Load
vds2
400V/div
ipri1
10A/div
ipri2
10A/div
ipri3
10A/div
500ns/div
π‘½π‘½π’Šπ’Šπ’Šπ’Š = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝑽𝑽𝒐𝒐 = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝟏𝟏𝟏𝟏𝟏𝟏𝟏 𝑳𝑳𝑳𝑳𝑳𝑳𝑳𝑳
Test Efficiency of 3P CLLC Converter
100
98.23% 98.15%
99
98
97
96
Eff/% 95
94
93
92
91
90
0%
20%
Test condition: Vin=850V, Vo: 850V, Po: 12.5kW
Power analyzer: Keysight PA2203A
@Room Temp.
1/5/2021
40%
60%
80%
100%
Load/%
Center for Power Electronics Systems
27
Design of Buck Converter Stage
Spec.
 Buck converter design
 Four phase interleaving buck topology
 Wide output voltage range
 CRM mode operation with ZVS extension to
achieve ZVS
 Negative coupling PCB winding inductors
L1 L1
1/5/2021
Vin
850V
Vo
200V-800V
Po_max
12.5kW
Io_max
22A
Io_phase
5.5A
Lself
30 µH
α
-0.5
L2
UIcore
core
12EI
Center for Power Electronics Systems
L2
28
PCB Winding Structure of Coupled Inductor
L1
N1=8
N2=8
L2
MMF
Case 1:
L1
N1=8
N2=8
L2
Case 2:
Wind.
Loss
(W)
Core
Loss
(W)
Total
Loss
(W)
Case 1:
w/o
interleaving
8.7
5.5
14.2
Loss
reduction
Case 2:
w/ interleave
6.7
6.2
12.9
10%
Note: Vin=850V; Vo=600V; Po=6.25 kW
1/5/2021
Center for Power Electronics Systems
29
Forward Operation @ Vo =600V, 100% Load
vBot1
400V/div
VBot2
400V/div
vBot3
400V/div
vBot4
400V/div
π‘½π‘½π’Šπ’Šπ’Šπ’Š = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝑽𝑽𝒐𝒐 = πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”, 𝑷𝑷𝒐𝒐 = 𝟏𝟏𝟏𝟏. πŸ“πŸ“πŸ“πŸ“πŸ“πŸ“
1us/div
Forward Operation @ Vo =600V, 100% Load
iL1+iL2
20A/div
iL1/iL2
10A/div
iALL
20A/div
iL3+iL4
20A/div
iL3/iL4
10A/div
1us/div
π‘½π‘½π’Šπ’Šπ’Šπ’Š = πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–πŸ–, 𝑽𝑽𝒐𝒐 = πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”πŸ”, 𝑷𝑷𝒐𝒐 = 𝟏𝟏𝟏𝟏. πŸ“πŸ“πŸ“πŸ“πŸ“πŸ“
Efficiency of Buck/Boost in Forward/Reverse Direction
100
99
Eff/%
98.62
97.96 98.61
98
97.11
97
98.83 98.97
99.19
99.04
98.91
97.19
Forward
Reverse
0
200
400
Test condition: Vin/Vo=850V, Vo/Vin: 200-800V, Po: 100%
Power analyzer: Keysight PA2203A
@Room Temp.
1/5/2021
99.56
99.58
98.01
96
95
99.15
600
800
1000
Vo/Vin/V
Center for Power Electronics Systems
32
Prototype and Efficiency
97.72
98
97.32
97.07 97.14
97.74
96.84
97.36
97.15 97.21
96.00 96.83
97
8.1in
96
Eff/%
96.05
95
94.49
94.57
94
Forward
Reverse
93
9.7in
100W/in3 (6.1kW/L)
1/5/2021
92
100
300
Center for Power Electronics Systems
500
Vo/Vin/V
700
900
33
Summary
 A Two stages DC/DC module with wide output voltage range from 200V
to 800V was proposed for battery charger application.
 The loss analysis and comparison between different PCB winding
configurations of three phase integrated transformer was discussed.
 The Negative coupling inductors with PCB winding structures were used
for four phase interleaving buck converter.
 97.7% peak efficiency
 100W/in3 (6.1kW/L) power density
Thank You
fengjin@vt.edu
1/5/2021
Center for Power Electronics Systems
34
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