A quick overview of the current sensing in power electronics converters is tested and analyzed. Then, SenseGaN technique along with the integration of semiconductors to monitor the power GaN module current without significant effects on power stage performance and opens a new era for smart devices in future power electronics. Various application for soft switching with this current measurement technique is also proposed.
Current Monitoring for Power GaN Transistors-SenseGaN Technique
1. Current Mirroring of Power GaN Transistor-
SenseGaN Technique
By: Mehrdad Biglarbegian
Team members: Namwon Kim, Shahriar Nibir
Ph.D. adviser: Babak Parkhideh
Electrical and Computer Engineering Department
Energy Production and Infrastructure Center (EPIC)
University of North Carolina at Charlotte
Contact: mbiglarb@uncc.edu, bparkhideh@uncc.edu
Phone: (704) 687-1959
January 12, 2018
2. 2/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
3. 3/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Goals
* Oak Ridge National Lab: Tolbert, et. al., “Power Electronics for Distributed Energy Systems and Transmission and Distribution Applications,”
➢ By 2030, 80% of all the electric power generated utilizes power electronics somewhere
between point of generation to the end-use*.
➢ Let’s go toward lower loss, circuit miniaturization, and performance enhancement.
Switching frequency is going high
High power density, and efficiency
Accurate & loss-less sensor
Fact
Demand
Demand
Options for accurate current sensors
at high frequency converters are limited!
Need to investigate alternative loss-less
and wideband current sensing techniques
Semiconductor and Gate Drive Circuits
Control development Filter Design
Sensing
Thermal
Management
We need current sensing in Power Electronics:
➢ Advanced control
➢ Ultra-fast protection
➢ Diagnostics/prognostics
4. 4/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
✓ Theoretically high BW.
✓ Topology dependent.
✓ Low accuracy @ high T.
✓ High loss.
Current Sensors
Non-Isolated Isolated
Current
Mirroring
Filter-
based
Resistive-
based
Inductor-
based
Hall-
Effect
Current
Transformer
Rogowski
Coil
Magneto-
Resistor
5. 5/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
Current Sensors
Non-Isolated Isolated
Current
Mirroring
Filter-
based
Resistive-
based
Inductor-
based
Hall-
Effect
Current
Transformer
Rogowski
Coil
Magneto-
Resistor
✓ Accurate.
✓ Very bulky.
✓ Works only for AC.
6. 6/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
Current Sensors
Non-Isolated Isolated
Current
Mirroring
Filter-
based
Resistive-
based
Inductor-
based
Hall-
Effect
Current
Transformer
Rogowski
Coil
Magneto-
Resistor
✓ Isolated
✓ Potentially high BW.
✓ Fast response.
✓ High current capability.
7. 7/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
• Even 2nH series inductance at high frequencies results in higher spikes across the switch.
• Needs over-design considerations and knowing perfectly the EMI on converter power stage.
SiLab sensors under 500kHz, 30V, 5A inverter:
Top Switch in full bridge converter
Bottom Switch in full bridge converter
• Rogowski-based:
SiLab sensors under 50kHz, 3A buck converter:
8. 8/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
Improved Inductor current with AKM-CQ3303
First porotype under 500kHz, 20A inverter.
• Hall effect sensor:
9. 9/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Motivations
Background
✓ Loss-less
✓ Current Capacity
✓ No bandwidth limitations Current Sensors
Non-Isolated Isolated
Current
Mirroring
Magneto-
Resistor
Hall-
Effect
Current
Transformer
Rogowski
Coil
Filter-
based
Resistive-
based
Inductor-
based
10. 10/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
11. 11/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
11
Dielectric
AlGaN
GaN
Substrate-Si
S G D
VGS
2DEG region
(Previously was built on: Sapphire, SiC)
GaN Transistors
Architecture
Gain
egative
• Higher Bandgap
✓ Potentially thinner and smaller device
• Higher critical electric field
✓ Potentially lower R-ds(ON)
• Lower capacitance charge
✓ Lower leakage current, and higher switching frequency
• Enhancement Mode GaN
➢ Sensitivity to the gate source voltage (5V)
➢ Dynamic R-ds(ON)
• High power switching frequency
➢ New techniques for control and measurement.
➢ System level reliability is still unforeseen.
12. 12/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
13. 13/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Current Mirroring
SenseGaN Technique
13
Dielectric
AlGaN
GaN
Substrate-Si
S G D
2DEG region
Current input path
Main
Switch
Sense
Switch
W/L=1W/L=n
Gate Signal
Vsense
ImainIsense
Vsense=Rsense*IsenseControl Unit
Isense << Imain
Current output path
14. 14/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Current Mirroring
System Description
http://epc-co.com/epc/Portals/0/epc/documents/presentations/CompoundSemi2015-Ditching%20the%20Package.pdf
http://www.mouser.com/pdfDocs/343654_GaNSystems__GN001_How_To_drive_GaN_EHEMT_Rev_20160426.pdf
15. 15/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Current Mirroring
Challenges
✓ Gate-Source voltage mismatching
✓ Suppression of voltage over-shoot
✓ Choosing proper resistor
Gate Signal
Vsense
Main
Switch
Sense
Switch
W/L=1W/L=n
16. 16/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Current Mirroring
Proposed Solutions
Virtual Grounding Circuit
Isolated Gate Driver
W/L=1W/L=n
in
Vout
V
Isolated Gate Driver
L
DSP
+
-
-
+
-
+
+
- Rsense
1Ω
Si8271
Si8271
10kΩ
10kΩ
1Ω 4.7kΩ
10Ω
2Ω
10Ω
4.7kΩ
2Ω
C R
6.8nF
1Ω
100kΩ
100kΩ
Power GaN Sense GaN
Power GaN
82pF
100kΩ
82pF
100kΩ
10pF
100kΩ
10pF
100kΩ
82pF
100kΩ
100kΩ
1nF
Iref load
LM6154
LM6154
LM6154
LM6154
S/H &
Logic
Circuits
VoutVin
10Ω
Ron(Q2)
Rsense
Ron(Q1)
ID
(b)
(a)
Q1 Q2
Delay on signal control path
17. 17/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Current Mirroring
Proposed Solutions
Isolated Gate Driver
W/L=1W/L=n
in
Vout
V
Isolated Gate Driver
L
DSP
+
-
-
+
-
+
+
- Rsense
1Ω
Si8271
Si8271
10kΩ
10kΩ
1Ω 4.7kΩ
10Ω
2Ω
10Ω
4.7kΩ
2Ω
C R
6.8nF
1Ω
100kΩ
100kΩ
Power GaN Sense GaN
Power GaN
82pF
100kΩ
82pF
100kΩ
10pF
100kΩ
10pF
100kΩ
82pF
100kΩ
100kΩ
1nF
Iref load
LM6154
LM6154
LM6154
LM6154
S/H &
Logic
Circuits
VoutVin
10Ω
Ron(Q2)
Rsense
Ron(Q1)
ID
(b)
(a)
Q1 Q2
𝑅 ሻ𝐷𝑆(𝑜𝑛 = 𝑅 ሻ𝐷𝑆(𝑜𝑛
25℃
𝑒൫𝑇−25℃ Τሻ 𝑘
𝐼 𝑄_𝑃𝑜𝑤𝑒𝑟
𝐼 𝑄_𝑆𝑒𝑛𝑠𝑒
= 𝑘 +
𝑅 𝑠𝑒𝑛𝑠𝑒
𝑅 𝐷𝑆 𝑜𝑛 𝑄1
25℃
𝑒
ቀ𝑇−25℃ Τሻ 𝑘 𝑄1
Better performance with GaN
Delay on signal control path
Virtual Grounding
20. 20/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
21. 21/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Experimental Development
Hardware prototype
DC+ DC-
Inductor
Isolated
Power Supply
SENSE GaN
Top Power GaN
Bot Power GaN
Load Connection
DSP-micro Controller
DC Supply for
Control Signals
• The prototype boost converter with GS66508T. [Qg = 6.5nC, Rds(on) = 55mΩ]
Manufacture Part Number Description
GS66508T GaN transistors
SI8271GB-IS Gate driver
LM6154BCM OpAmp 100MHz Bandwidth
PHP02512E20R0BST5 20Ω 0.1% Sense resistor
CL10C820FB8NNNC 82pF Filter capacitor
22. 22/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Experimental Development
SenseGaN results-150kHz, and 5A.
Inductor Current
SenseGaN
Time-µsec
Time-µsec
Gate SignalsControl Signals
23. 23/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Experimental Development
SenseGaN results-50kHz, and 5A
Blue:
Inductor Current
Time-µsec
Orange:
SenseGaN at 80% duty cycle
Orange:
SenseGaN at 20% duty cycle
Blue:
Inductor Current
Time-µsec
Time-µsec
24. 24/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
25. 25/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Application in Power Converters
SenseGaN for soft-switching
✓ Switching at Zero Current to reduce switching loss.
✓ There is no current sensor to achieve this possibility in the market.
26. 26/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Application in Power Converters
SenseGaN for soft-switching
Inductor Current
Average current for CCM and BCM
DCM
CCM
SenseGaN
Measurements
Trigger Reference
DCMCCM di
dt
Vth
Tdelay
Reference PWM
Trigger Signal
CCM
BCM
delay
Reference PWM
Trigger Signal
delay delay
no delay in CCM
BCM
BCM
27. 27/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Application in Power Converters
Proposed technique for ZCS
Gate Drive
in
Vout
V
Gate Drive
L = 33u
DSP +
-
-
+
-
+
+
- Rsense
Ω
Si8271
Si8271
10k
10k
Ω 4.7k
Ω
Ω
Ω
4.7k
Ω
C = 1u R
82pF
1k
100k
1k
Power GaN Sense GaN
Power GaN
GS66508T
100k
10pF
100k
10pF
100k
82pF
100k
load
+
-
TLV3502
Comperator
LM6154
LM6154
LM6154
LM6154
VThreshold
Ω
GS66508TGS66508T Q1 Q2
100k
100k
Vout
Vin
ADC
Trigger
Virtual grounding and analogue signal processing
Active Device Sensing Device
Synchronous Device
dDCM
Operation
Δf
Δf
TSW
Region
dBCM
dCCM
28. 28/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Application in Power Converters
Closed loop ZCS control of a boost with SenseGaN
Inductor Current
Trigger- Delay
SenseGaN
Duty: 40% 60%
29. 29/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
30. 30/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Iso-SenseGaN
Proposing a new solution for improving the SenseGaN technique
Drain Drain
Source
Source
Gate Gate
▪ One of the drawback of current mirroring techniques (SenseGaN) is lack of galvanic isolation.
▪ Difficulties get severe where the active switch measurement is required for (>30V).
➢ Therefore, Iso-SenseGaN is proposed for …
33. 33/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Comparator
60Hz
0
GB2
GB1
Comparator
I_ref
S1
A
B
A
B
ON OFF
ON
OFF
GA1
Comparator
I_ref
S2
A
B
ON OFF GA2
If
GB1 = ON
If
GB2 = ON
Vload
Iload
IS1 IS2
Iso-SenseGaN
Closed loop ZCS control of a DC-AC with SenseGaN
Vs
SB2
SA1 SA2
SB1
Current Sensing Unit
Linv
R1
Q3
Q1 Q2
Q4
34. 34/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Iso-SenseGaN
Closed loop ZCS control of a DC-AC with SenseGaN
Vs
GB2
GA1 GA2
GB1
Current Sensing Units
Linv
Load
Q3
Q1 Q2
Q4
Vs
GB2
GA1 GA2
GB1
Current Sensing Units
Linv
Load
Q3
Q1 Q2
Q4
Vs
GB2
GA1 GA2
GB1
Current Sensing Units
Linv
Load
Q3
Q1 Q2
Q4
Vs
GB2
GA1 GA2
GB1
Current Sensing Units
Linv
Load
Q3
Q1 Q2
Q4
S2 S1 S2 S1
S2 S1 S2 S1
35. 35/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Contents
• Motivations
• GaN Transistors
• Current Mirroring in GaN
• Experimental Development
• Application in Power Converters
• Isolated-SenseGaN Measurement Technique
• Conclusion
36. 36/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
➢ A novel current mirroring technique for GaN transistor is presented.
➢ The solutions are compatible with the lateral/vertical GaN structures.
➢ SenseGaN characteristics and implementation challenges were
discussed in both the simulations and experimental results.
➢ The application of SenseGaN technique was verified in a DC-DC
boost converter in closed loop control under quasi soft-switching.
➢ The new isolation is added externally on the sensing path to avoid
common mode issues.
➢ This technique is also adaptable for other DC-DC buck converters as
well as DC-AC converters (inverters), and many common typical
power electronics topologies.
Conclusion
37. 37/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Publications from the presented work
• Boundary Conduction Mode Control of a Boost Converter With Active Switch
Current-Mirroring Sensing
(IEEE Transactions on Power Electronics: Published on January-2018)
Mehrdad Biglarbegian, Namwon Kim, and Babak Parkhideh-UNCC, USA
• Characterization of SenseGaN Current-Mirroring for Power GaN with the
Virtual Grounding in a Boost Converter
(IEEE ECCE 2017: Published on September-2016)
Mehrdad Biglarbegian, and Babak Parkhideh-UNCC, USA
• Development of Isolated SenseGaN Current Monitoring for Boundary
Conduction Mode Control of Power Converters
(IEEE APEC: will be published)
Mehrdad Biglarbegian, Namwon Kim, Tiefu Zhao, and Babak Parkhideh-UNCC, USA
• Development of Current Measurement Techniques for High Frequency Power
Converters
(IEEE INTELEC 2016: Published on October-2016)
Mehrdad Biglarbegian, Shahriar Nibir, Hamidreza Jafarian, and Babak Parkhideh-UNCC, USA
• Current Monitoring for Power GaN Transistors
(Application Patent: Filed on January-2017)
Mehrdad Biglarbegian, Namwon Kim, and Babak Parkhideh-UNCC, USA
• Demonstration on the YouTube:
https://www.youtube.com/watch?v=42IQ_ZvXOQ4&t=33s
38. 38/39Contact: mbiglarb@uncc.edu, Ph.D. adviser: bparkhideh@uncc.edu
Thanks!
PV Integration Lab, EPIC, University of North Carolina at Charlotte, Charlotte, NC, USA