DEVELOPMENT OF COMPACT VARIABLE-VOLTAGE, BI-DIRECTIONAL 100KW DC-DC
CONVERTER
Leonid Fursin1, Maurice Weiner1
Jason Lai2, Wensong Yu2, Junhong Zhang2, Hao Qian2
Kuang Sheng3, Jian H. Zhao3, Terence Burke4, and Ghassan Khalil4
1United Silicon Carbide, Inc., New Brunswick Technology Center, Building A, New Brunswick, NJ 08901, USA
2FEEC, ECE Department, Virginia Tech, Blacksburg, VA24060, USA3SiCLAB, ECE Dept., Rutgers University, 94 Brett Road, Piscataway, NJ 08854, USA
4 U.S. Army TARDEC, Warren, MI 48397-5000, USAfor
AECV-2007
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1. REPORT DATE 11 JUN 2007
2. REPORT TYPE N/A
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4. TITLE AND SUBTITLE Development of Compact Variable-Voltage, Bi-Directional 100KWDC-DC Converter
5a. CONTRACT NUMBER
5b. GRANT NUMBER
5c. PROGRAM ELEMENT NUMBER
6. AUTHOR(S) Leonid Fursin; Maurice Weiner; Jason Lai; Wensong Yu; JunhongZhang; Hao Qian; Kuang Sheng; Jian H. Zhang; Terence Burke;Ghassan Khalil
5d. PROJECT NUMBER
5e. TASK NUMBER
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7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) US Army RDECOM-TARDEC 6501 E 11 Mile Rd Warren, MI 48397-5000
8. PERFORMING ORGANIZATION REPORT NUMBER 17101
9. SPONSORING/MONITORING AGENCY NAME(S) AND ADDRESS(ES) 10. SPONSOR/MONITOR’S ACRONYM(S) TACOM/TARDEC
11. SPONSOR/MONITOR’S REPORT NUMBER(S) 17101
12. DISTRIBUTION/AVAILABILITY STATEMENT Approved for public release, distribution unlimited
13. SUPPLEMENTARY NOTES Presented at the 7th AECV Conference, June 11-13, 2007, Stockholm, Sweden, The original documentcontains color images.
14. ABSTRACT
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Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18
OutlineOutlineProject goalsPower Stage DesignDSP controller, interface circuit and gate driver implementationPower stage layout and packagingConverter testing Summary and Conclusions
Project GoalsProject Goals
Bidirectional dc-dc converter targets: Input voltage range: 200 - 300 VDC (battery pack voltage) Output voltage range: 300 - 600 VDC Bidirectional power flow Continuous Power: 100 kW, Peak: 150kWPower density: 4 to 8 kW/literSpecific power density: 4 to 6 kW/kgTotal efficiency: ≥ 95%SVM frequency: ~20kHzCoolant Temperature: ≥ 90oC
InnovationsInnovationsA novel yet simple zero-voltage soft-switching scheme
without adding any extra switchmaking a 25KHz switching frequency possible
High-end digital signal processor controllerallow fast and smooth mode transition
An interleaving 3-phase designsubstantially reducing the ripple current and filter capacitor size
Nano-inductor designHigh permeability, high saturation flux density lead to small inductor size
SiC Schottky diode-Si IGBT power modules Minimized thermal resistanceRobust diodes, zero-recovery charge
POWER STAGE DESIGN
Proposed Soft-switching Bi-directional DC/DC Converter with Lossless SnubbersProposed Soft-switching Bi-directional DC/DC Converter with Lossless Snubbers
Load/Source
Ld1
Ld3
S1u S2u
S1d S2d
300 -800 VH
igh
freq
. cap
.
S3u
S3d
Ld2
200 -300 V
C
A special switching scheme that utilizes unused switches to perform soft switching: The basic idea is to have the unused switch turned on while the active switch is turned off.
This will allow current continuously flow in opposite direction, thus avoiding the discontinuous current and parasitic ringing. Now to reduce the turn-off loss, we can put the lossless snubber
across the device to slow down the rate of switching.
Overall hardware system structure: power stage, gate driver and DSP controller
Overall hardware system structure: power stage, gate driver and DSP controller
TMS2808
GATE DRIVER
Power Stage in Bidirectional Soft-switched DC/DC Converter
V-low
V-high
A0
A1
000
01
A0
Boost-I10Boost-V00
Buck-V01
Buck-I11Stopxx
ModeA2A1
I –inductor3
I –inductor2
I –inductor1
A2
SIGNALCONDITIONING
EP
WM
ADC G
PIO
SYSTEMCLOCK
INTERRUPT SYSTEM
DSP Controller
TMS2808
GATE DRIVER
Power Stage in Bidirectional Soft-switched DC/DC Converter
V-low
V-high
A0
A1
000
01
A0
Boost-I10Boost-V00
Buck-V01
Buck-I11Stopxx
ModeA2A1
I –inductor3
I –inductor2
I –inductor1
A2
SIGNALCONDITIONING
EP
WM
ADC G
PIO
SYSTEMCLOCK
INTERRUPT SYSTEM
DSP Controller
Summary of Testing Results of IGBT LossSummary of Testing Results of IGBT Loss
0
10
20
30
40
50
60
0 50 100 150 200 250 300 350
Current (A)
Turn
-off
ener
gy (m
J)
w/o capacitor
with 0.14μF
VDC=700V, Csnub= 0.14μF
×3 loss reductionAchieved without extra switches/inductors
Inductor DesignInductor Design
A superior core, FINEMET®, is usedHigh permeability, high flux density
Inductor Design Verification Inductor Design Verification
iC (100A/div)
iL (100A/div)vCE1 (100V/div)
vGE1 (10V/div)
t (5µs/div)
Saturation Point=456A
L=14.5μH, ISAT=456A, 20% design margin
Each inductor core:3.35kg, 0.47 liter
Liquid cooled heatsink designLiquid cooled heatsink design
Liquid-cooledθth<0.01°C/W
Physical Layout Dimensions of IGBTsPhysical Layout Dimensions of IGBTs
DSP controller, interface circuit and gate driver
implementation
Auxiliary Gate Drive Power SupplyAuxiliary Gate Drive Power Supply
0.50
19.65
7.0510.20
2.5415.24
1 2
5 6 7
4.10
1 2
5 6 7
MSV
H-241505
100mA
/–100mA
•C
TC
Pin no Function
1 +Vin
2 –Vin
5 –Vout
6 COM
7 +Vout
The gate driver power supply module provides isolated outputs of +15V and –5V at ≥90°C.
DSP TMS320F2808 function blocksDSP TMS320F2808 function blocks
Simulation results for the efficiency of boost mode and buck mode
Simulation results for the efficiency of boost mode and buck mode
0.90.910.920.930.940.950.960.970.98
400 450 500 550 600 650 700
Boost Mode
Output Voltage (V)
Effic
ienc
y
Vin = 200V
Vin = 300V
0.90.910.920.930.940.950.960.970.98
400 450 500 550 600 650 700
Boost Mode
Output Voltage (V)
Effic
ienc
y
Vin = 200V
Vin = 300V
Boost mode efficiency
0.90.910.920.930.940.950.960.970.98
400 450 500 550 600 650 700
Buck Mode
Input Voltage (V) Ef
ficie
ncy
Vo = 200V
Vo = 300V
0.90.910.920.930.940.950.960.970.98
400 450 500 550 600 650 700
Buck Mode
Input Voltage (V) Ef
ficie
ncy
Vo = 200V
Vo = 300V
Buck mode efficiency
Power stage layout and packaging
Converter moduleConverter moduleInductors
IGBT modulesGate driver board
Fiber-optical cables
• The DSP controller includes signal conditioning circuit and TMS320F2808 digital signal processor.
DSP controller with interface board
The IGBT driver circuit
• Provides electrical isolation by optocouplers, fiber optics, and by transformers• With overcurrent detection and pulse-by-pulse overcurrent protection function
The Power Stage Layout
• With minimized size of the inductors for 100kW output power• Zero-voltage switching on and zero-voltage switching off with capacitor• Compact bus capacitor size with Interleaving ripple cancellation
Converter testing with Coolant at 90oC
iL(100A/div)
iLall (100A/div)
vo (100V/div)
t(10µs/div)
iL(100A/div)
iLall (100A/div)
vo (100V/div)
t(10µs/div)
Measured Current Waveforms
Inductor current ripple is greatly reduced by interleaving three phases
Detailed Measured Waveforms in 100kW Load
• Switch is turned on under ZVS condition.
vGE (10V/div)
vCE (200V/div)
–iL (100A/div)
t(2µs/div) Turn-offTurn-on
Test condition : Vin=450V, Vout=280V, P=100KW
• Note that Inductor current negated.
Start-up Voltage and Current Waveforms at 108-kW Operation in Boost Mode
Start-up Voltage and Current Waveforms at 108-kW Operation in Boost Mode
Transient response of the converter under boost mode operation with a step load
change from no load to 80-kW
Transient response of the converter under boost mode operation with a step load
change from no load to 80-kW
200A
400V
ia (100A/div)
vo (200V/div)
io (100A/div)
50
60
70
80
90
100
0 10 20 30 40 50 60 70 80 90 100
Output Power (kW)
Effi
cien
cy (%
) Experimental ResultsAnalytical Results
• Maximum efficiency is around 97%
Test condition : Vin=450V, Vout=280V, buck mode
Experimental efficiencies in Buck Mode (450V input and 280V output)
50556065707580859095
100
0 10 20 30 40 50 60 70 80 90 100Output Power (kW)
Effic
ienc
y (%
)
Experimental ResultsAnalytical Results
Experimental efficiencies in Boost Mode(240V input and 360V output)
• Maximum efficiency is around 98%
SummarySummarySi-based soft-switching bidirectional DC-DC converter has been successfully demonstrated
Novel soft-switching circuit without extra switch/inductorDSP (TI-TMS320F2808), inductor, gate driver, optical fiber interface designed
Successfully tested at 90°C temperature for 30-kW continuous and 108-kW.Efficiency of 97-98% achieved in both buck and boost modesCompact size (less than 25 liters) demonstratedSiC/Si hybrid power modules being packaged for DC-DC converter operating at high coolant temperature >90oCSix phase interleaved design will reduce stress to inductors for robust long-term reliable DC-DC converter for FCS
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