Cree SiC MOSFET Performance Advantages in High Frequency Power

SiC MOSFET Performance Advantages in High Frequency Power Conversion Applicationseque cy o e Co e s o pp cat o s

--Demonstrating the Advantages of SiC MOSFETs

Using a SEPIC ConverterUsing a SEPIC Converter

March, 2012

Introduction

• Use SEPIC converter to demonstrate SiC MOSFET pe fo mance ad antages o e silicon de icesperformance advantages over silicon devices

• Equating the results from the SEPIC converter to a particular applicationa particular application

• Comparison of the Cree CMF10120D and CMF20120D 1 2 kV SiC MOSFETs with a 1 2 kV SiCMF20120D 1.2 kV SiC MOSFETs with a 1.2 kV Si IGBT and 1.2 kV Si MOSFET

Copyright © 2012, Cree, Inc. pg. 2

SEPIC Converter Demonstrator System

Sepic converter characteristics:Sepic converter characteristics:• Simple – only one switch• Output power recirculated back to input

N l d i d– No load required– Efficiency easy to precisely measure– Switch operated at ~ 50%

Vin

• Switch ground referenced for precise voltage and current measurement

• Inductors can be overdesigned so that All that is required is to adjustloss does not vary much with frequency

• Switch sees 2x input voltage reduces power supply voltage requirements

All that is required is to adjust voltage, current and frequency to match application operating conditions p pp y g q

pg. 3Copyright © 2012, Cree, Inc.

Why SEPIC Converter?

• SimpleR i l h b k h i• Recirculate the output power back to the input – No need for a load while maintaining switch stress

Allows precise system loss measurement at a given set– Allows precise system loss measurement at a given set of conditions

• Switch referenced to groundg– Easy voltage and current measurement

• Allow easy frequency adjustment with minimal impact on overall system loss


Why Recirculate the Power?

• System loss is the difference between input and output poweroutput power

• For a high efficiency system, total power loss is very smallvery small

• The accuracy of power measurement is critical• By recirculating the output power back to the• By recirculating the output power back to the

input, the system loss is simply the input power which can be accurately measuredy


Some Application Facts

• All candidate applications operate their switches at a specified voltage current switchingat a specified voltage, current, switching frequency and case temperature

• A demonstrator operating the switch under the• A demonstrator operating the switch under the same specified conditions as the application will robustly illustrate the relative advantages y gbetween technologies


Detailed Schematic

Sepic converter design:

D i t i d ith• Drain current is sensed with a T & M Research current viewing resistor

• A BNC connector is provided for the VDS probe

• Isolated gate driver used to eliminate ground loop with current viewing resistor

• Switch sees 2x input voltage reduces power supply voltage requirements


Inductor Design

Pwind Pcore Ptotal10

s (W

)

Total Inductance = 3.3 mH Inductor design:1

r Tot

al A

C L

oss

Design goal: Minimum AC loss from 30 kHz to > 300 kHz• A U-U93 3C90 ferrite core was used

0.1

Indu

ctor to minimize losses (at the cost of

size)• Litz wire 540xAWG40 was used to

minimize skin and proximity effect0.01

minimize skin and proximity effect• Three air gaps were used to

minimize wire loss

0.00110 100 1000

Frequency (kHz)


Device Demonstration

• Comparative performance of the SiC MOSFET in almost any hard-switched application can be ascertained using a SEPIC converter

• All that is required is to operate the SEPIC switch at the same voltage, current, frequency and temperature as the switches in the application such as:

Motor DrivesDC-DC ConvertersPower Factor Controllers

DC

EV Battery Chargers Utility Tie Solar Inverters


Application Examples

Consider SEPIC demo runningBoost Converter• Input Voltage = 400 VConsider SEPIC demo running

under these conditions:• Switch Voltage = 800V• Switch Current = 20A pk, 50 % Du

Input Voltage 400 V• Output Voltage = 800 V• Output Power = 8 kW

Buck Converter• Input Voltage = 800V• Output Voltage = 400V

Output Power 8 kWThe relative switch

• Output Power = 8 kW

PFC

performance results are exactly the same as for these typical applications

• Input Voltage = 480 VAC• Output Voltage = 800 VDC• Output Power = 12.8 kW

3 Phase Inverter• Input Voltage = 800 VDC• Output Voltage = 480 VAC

O t t P 20 kW

DC IN 3 PHASE AC OUT

• Output Power = 20 kW


SEPIC Demonstration

• The SEPIC converter was used to compare the l ti t l d ffi i b trelative system losses and efficiency between

Cree’s 1.2 kV SiC MOSFETs and representative 1 2 kV silicon switches in TO-247 packages1.2 kV silicon switches in TO-247 packages

• The silicon switches were:– IGW40N120H3 trench and field stop 1.2 kV 40A IGBT.IGW40N120H3 trench and field stop 1.2 kV 40A IGBT.– APT28M120B2 1.2kV 28A Si MOSFET


1.2 kV TO-247 Switch Comparison

Cree SiCParameter

Cree SiC MOSFET

CMF20120D

Si IGBTIGW40N120H3

Si MOSFETAPT28M120B2 Comments

BreakdownV lt

1.2kV 1.2kV 1.2kV SameVoltage

Maximum ContinuousCurrent

17A @ TC=100°C

40A @ TC=100°C

17A @ TC=100°C APT28M120B2 has similar max current and is largest Si MOSFET in TO-247 package

Forward Voltage Drop @ 20A

1.68V @ TJ=25°C1 98V @

1.70V @ TJ=25°C1 79V @

9.6V @ TJ=25°C IGW40N120H3 has similar voltage drop at half rated current!1.98V @

TJ=150°C1.79V @ TJ=150°C

half rated current!

Gate Charge 91 nC @ 20V 185 nC @ 15V 300 nC @ 10V CMF20120D has lowest gate charge

Gate Energy 1.82 µJ 2.78 µJ 3 µJ CMF20120D has lowest gate energy even with 20V drive


Efficiency Comparison in 30 kHz Hard Switched Application

Efficiency Comparison at 30 kHz

99%IGW40N120H3 CMF20102D APT28M120B2 CMF10120D Cree SiC MOSFETs handles

more current at higher efficiency

Competitive Devices:• High switching loss limits

IGW40N120H3 Si IGBT

98%

cien

cy

IGW40N120H3 Si IGBT• High conduction loss limits

APT28M120B2 Si MOSFET96%

97%

Ove

rall

Effic

Comparison Conditions:• Switching Freq = 30 kHz• Switch Voltage = 800V

D t c cle 50%

95%

• Duty cycle = 50%→ Avg current = ½ peak current

94%0 5 10 15 20 25

Peak Switch Current @ 50% Du (A)Peak Switch Current @ 50% Du (A)


Switch Loss Relative to CMF20120D vs. Switch Current @ 30 kHz

60APT28M120B2

IGW40N120H3 Cree SiC MOSFET handles

40

50

W)

Peak Current Comparison:

10A max IGW40N120H312A max

CMF10120D18.5A max

Cree SiC MOSFET handles more peak current

30

40

CM

F201

20D

(W Peak Current Comparison:(Test terminated when max heatsink temp reached)• CMF20120D = 25A peak

18.5A max

10

20

ss R

elat

ive

to C CMF20120D 25A peak

• CMF10120D = 18.5A peak• IGW40N120H3 = 12A peak

o Limited by high switching lossAPT28M120B2 10A k

CMF20120D Baseline25A max

10

0

Los • APT28M120B2 = 10A peak

Limited by high conduction loss

C i C di i-100 5 10 15 20 25 30

Peak Switch Current @ 50% Du (A)

Comparison Conditions:• Switching Freq = 30 kHz• Switch Voltage = 800V• Duty cycle = 50%Relative Switch Loss = DUT Loss – CMF20120D Loss


Switch Loss Relative to CMF20120D vs. Delivered Power @ 30 kHz

60

50

60

APT28M120B22 kW max

IGW40N120H32.4 kW max

CMF10120D

Cree SiC MOSFET provides highest delivered power

30

40

F201

20D

(W) CMF10120D3.7 kW max Delivered Power

Comparison:(Test terminated when max heatsink

d d)

20

ativ

e to

CM

F

CMF20120D Baseline5 kW

temp exceeded)• CMF20120D = 5 kW • CMF10120D = 3.7 kW• IGW40N120H3 = 2.4 kW

0

10

Loss

Rel

a 5 kW max IGW40N120H3 2.4 kWo high switching loss

• APT28M120B2 = 2 kWo high conduction loss

-100 1000 2000 3000 4000 5000 6000

Delivered Power (W)

Comparison Conditions:• Switching Freq = 30 kHz• Switch Voltage = 800VSwitch Voltage 800V• Duty cycle = 50%Relative Switch Loss = DUT Loss – CMF20120D Loss


Efficiency Comparison in 100 kHz Hard Switched Application

CMF10120 CMF20120 APT28M120

96%

97% Cree SiC MOSFETs handles more current at higher efficiency

Competitive Devices:• Impractical to compare to

IGW40N120H3 Si IGBT95%

96%

cy

g y

IGW40N120H3 Si IGBT• High conduction loss limits

APT28M120B2 Si MOSFET94%

95%

Effic

ienc

Comparison Conditions:• Switching Freq = 100 kHz

h l93%

94%

• Switch Voltage = 800V• Duty cycle = 50%

92%

93%

0 5 10 15 20 25Peak Switch Current @ 50% Du (A)


Switch Loss Relative to CMF20120 vs. Peak Switch Current @ 100kHz

60

50

60

APT28M120B28.5 A max

CMF10120D14 A max

Cree SiC MOSFET handles more peak current

30

40

F201

20D

(W) Peak Current Comparison:

(Test terminated when max heatsink temp reached)

CMF20120D 18 A peak

10

20

ativ

e to

CM

F

CMF20120D Baseline18 A max

• CMF20120D = 18 A peak• CMF10120D = 14 A peak• APT28M120B2 = 8.5 A peak

o Limited by high conduction loss

-10

0

Loss

Rel

a

Comparison Conditions:• Switching Freq = 100 kHz


-200 5 10 15 20 25

Peak Switch Current @ 50% Du (A)

• Switching Freq = 100 kHz• Switch Voltage = 800V• Duty cycle = 50%

Relative Switch Loss = DUT Loss – CMF20120D Loss


Switch Loss Relative to CMF20120D vs. Delivered Power @ 100 kHz

60

50

60

APT28M120B21.7 kW max

CMF10120D2.8 kW max

li d i

Cree SiC MOSFET provides highest delivered power

30

40

0120

D (W

) Delivered Power Comparison:(Test terminated when max heatsink temp exceeded)• CMF20120D = 3 6kW

10

20

ve to

CM

F20

CMF20120D Baseline3.6 kW max

• CMF20120D = 3.6kW • CMF10120D = 2.8kW• APT28M120B2 = 1.7kW


-10

0

Loss

Rel

ativ

Comparison Conditions:-20

0 1000 2000 3000 4000 5000Delivered Power (W)

p• Switching Freq = 100 kHz• Switch Voltage = 800V• Duty cycle = 50%

Relative Switch Loss = DUT Loss – CMF20120D Loss


Summary

• Demonstration of the advantages of SiC MOSFETs can be accomplished with a SEPIC convertercan be accomplished with a SEPIC converter.

• A SEPIC converter allows the accurate measurement of relative performance betweenmeasurement of relative performance between different switches

• These results can be translated to specificThese results can be translated to specific applications

• A comparison was made between 1.2 kV SiC pMOSFETs and competing 1.2 kV silicon IGBTs and MOSFETs

• The SiC MOSFET performance was superior at 30 kHz and at 100 kHz

Copyright © 2012, Cree, Inc. pg. 19

Cree SiC PowerThe material difference.

Cree SiC MOSFET Performance Advantages in High Frequency Power

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