SiC MOSFET based 50kW DC/DC Boost Converter in PV...
Transcript of SiC MOSFET based 50kW DC/DC Boost Converter in PV...
SiC MOSFET based 50kW DC/DC Boost
Converter in PV Application Rev 2, 12/3/13
Cree Power Applications
1
Overview
1. Typical PV Boost systems in PV applications
2. Why consider a design with SiC devices?
3. 50kW Boost converter evaluation unit
4. Test results
5. Availability and other details
2 Copyright © 2012, Cree Inc.
Typical 3-ph String Inverter Topology with Si Devices
Copyright © 2013, Cree Inc.
MPPT BOOST+3Level Inverter: 1200V IGBTs for Booster+600V IGBTs for three-level inverter
Low frequency with10kHZ-20kHZ because of Si IGBT limitation
Heavy weight and large size, thus low power density
High passive magnetic cost because of low frequency
3
ZVT Three-level Boost Converter Topology
Copyright © 2013, Cree Inc.
Source: Michael T. Zhang, Yimin Jiang, Fred C. Lee in APEC1995 ZVT aux circuit
ZVT Three-level Boost Benefits:
600V Si MOSFET devices
Higher frequency operation
Zero voltage soft switching
Higher efficiency
ZVT Three-level Boost Drawbacks:
Additional switcher for aux circuit
Complicated control method
Output DC link voltage unbalance issue
4
Key Advantages of Using SiC MOSFETs
Copyright © 2013, Cree Inc.
SiC power semiconductors are superior to
silicon in 3 critical properties:
– Wider bandgap: SiC supports 10 times higher
electric fields than Si
– Higher thermal conductivity: SiC supports 3
times the power density of Si
– Reliability: 10X better than silicon
SiC MOS Key Benefits Vs Si:
Low conduction losses
Low switching losses
Enabling high frequency
No current tailing for IGBT Turn-on Turn-off
On State
Off State Off State
5
Key Advantages of Using SiC Schottky diodes
I C
urr
en
t (A
)
-10
-8
-6
-4
-2
0
2
4
6
8
10
-1.0E-07 -5.0E-08 0.0E+00 5.0E-08 1.0E-07 1.5E-07 2.0E-07
CSD10060
TJ = 25, 50, 100, 150°C
600V, 10A Si FRED
TJ = 25°C
TJ = 50°C
TJ = 100°C
TJ = 150°C Silicon’s
Wasted Energy!
Cree’s SiC Switching
Waveform –
Constant over Temp
Time (s)
Almost zero reverse recovery energy independent of device temperature.
6
50kW, 4 phase Interleaved Boost Converter Features
2x devices hard paralleled per phase
4 phase interleaved Boost with full SiC devices Input voltage: 400V-600Vdc
Output voltage: 800Vdc
Output power: 50KW (12.5KW per channel)
Controller preset
2x independent MPPT channels
Copyright © 2013, Cree, Inc.
2pcs
C4D10120D
2pcs
C4D10120D
2pcs
C4D10120D
2pcs
C4D10120D
Inverter
StageA B C
A
B
C
800V-1000Vdc
2pcs
C2M0080120D
A Channel
4pcs
150uF/
600V
B Channel
C Channel
D Channel
Solar Panel
MPPT 1
400Vdc~800Vdc
Solar Panel
MPPT 2
400Vdc~800Vdc
2pcs
C2M0080120D
2pcs
C2M0080120D
2pcs
C2M0080120D
Phase A
Phase B
Phase C
Phase D
7
Electrical Specifications
8 Copyright © 2012, Cree Inc.
Parameter Unit Value
DC output voltage VDC 800
Max. output power kW 50
DC input voltage VDC 400 – 600
Efficiency % 97.8 – 99.14
Switching Frequency / phase kHz 75
Operating temp* ºC -25 to +35
Storage temperature range ºC -35 to +85
Isolation voltage kV tbd
Hardware designed as an evaluation platform and not a qualified product.
* Restriction imposed due to limited testing for evaluation products.
PCB Assembly Of The 50kW Evaluation Unit
EMI Filter Choke
Boost Chokes*
Controller
2pcs C2M0080120D
per each phase
Phase Gate
driver
MPPT
Ch B
MPPT
Ch A
Copyright © 2013, Cree, Inc. 9
Measured Versus Calculated Efficiency Over Varying Load
Note: Gate to source turn on resistor is 15Ohm and turn off resistor is 5Ohm
Ambient temperature is 25°C with fan cooling
Copyright © 2013, Cree, Inc.
97.13%
98.28%
98.75%
98.92%
99.06% 99.11% 99.06%
98.87%
98.52%
97.80%
98.60%
98.91%
99.20% 99.28% 99.36% 99.41% 99.34%
99.14%
96.0%
96.2%
96.4%
96.6%
96.8%
97.0%
97.2%
97.4%
97.6%
97.8%
98.0%
98.2%
98.4%
98.6%
98.8%
99.0%
99.2%
99.4%
99.6%
5% 10% 20% 30% 40% 50% 60% 80% 100%
Eff
icie
ncy
Loading (%)
50KW Interleaved Boost Converter with 800V DC Output
Prototype @400VDC Input
Prototype @600VDC Input
Predicted @600VDC Input
10
Waveforms With 600VDC Input And 800VDC Output (D=25%)
Vds1 (500V/div)
Vds2 (500V/div)
Il(10A/div)
Copyright © 2013, Cree, Inc.
Turn-Off detail Turn-On detail
Hard paralleled
MOSFETs
on each phase
5uS/div
200nS/div 200nS/div
11
Waveforms With 400VDC Input And 800VDC Output (D=50%)
Vds1 (200V/div)
Vgs (10V/div)
Il(10A/div)
Copyright © 2013, Cree, Inc.
Turn-Off detail Turn-On detail
5uS/div
200nS/div 200nS/div
12
Thermal Images With 400V In / 800V Out at Full Load
C2D0080120D C4D10120D
Part Tc (°C) #1 Tc (°C) #2
C2M0080120D 92.6 94.4
C4D10120D 67.5 64.9
Boost Inductor 69.7
Note: Testing is based on full load operation after 30min with fan to cool system
Ambient temperature = 25ºC
Boost Inductor
Copyright © 2013, Cree, Inc. 13
Electrical Connectors
14 Copyright © 2012, Cree Inc.
Power Terminals Use AWG2 / 35mm2 Cable
CON 1 In, Ch A Pos
CON 2 In, Ch A Neg
CON 3 In, Ch B Pos
CON 4 In, Ch B Neg
CON 5 Out Pos
CON 6 Out Neg
CON 21 Out, HV aux. pos
CON 22 Out, HV aux. neg
Aux. Power CON 16 6 pin 2.54mm connector
1 Vee -2VDC
2 PV_-Ve PWR Ground
3 18V_HV +18VDC
4 PV_-Ve PWR Ground
5 n/c
6 PV_-Ve PWR Ground
CON 6
CON 5
CON 3
CON 4
CON 2
CON 1
2x 94mm, 12VDC fans
connected to CON 20. CON 21
CON 22
CON 16
Top View
Bottom View
Mechanical Detail
15 Copyright © 2012, Cree Inc.
Unit size: 530mm X 365mm X 174mm
Weight (as shown): 10Kg
Cooling: 2x 94mm, 12VDC Fans
Mounting: 10x M6 bolts
Confidential
FAQ
1. How does this compare to a Si solution?
SiC MOSFETs allows the designer to take new directions in design and its not always possible to make meaningful
comparisons. It is unlikely that we would use Si in a such a hard switched, high power and high Fsw application. A
comparative case study has been completed on a 10kW system by Cree in the past and its results should scale well
at 50kW.
2. What is the core and wire used to make boost inductors?
18 strand 25 AWG copper wire with polyurethane / Nylon coating.
3. What is the highest dv/dt measured during switching?
Approximately 50 V/nS.
4. How does EMI signature compare to Si based solution?
The EMI signature is highly dependent on the final package and cost effective mitigating solutions finally implemented
in the product. Since the purpose of the evaluation board is to provide a platform for customers to evaluate SiC
MOSFETs, the EMI aspect has not been tested.
A small ferrite bead with high impedance over 10MHz is used to reduce ringing on the gate lead of the SiC MOSFETs.
The bead is from Wurth Electronik p/n 74270011.
5. What is CON15 used for?
It is used for a different configuration with a digital control card and should not be used by the customer.
17 Copyright © 2012, Cree Inc.