Bertrand Rivet STMicroelectronics

TOURS

SiC Diodes in Switching

Power Converters

Summary2

1. Some applications of SiC diodes

2. Main benefits versus PN diodes

3. Comparison between first and second

generation of SiC diodes

4. Critical phases in PFC application

5. Electro-thermal model of SiC diode

6. Examples of simulation

7. Recommendations of design

Saint-Nazaire / Electronique de puissance

Seminar, Thursday June 12, 2014

Single - Interleaved PFC

600/650V diodes

VOUT

Vmains

L Dboost

Vgate

IRM

3

PFC Overview: Bridgeless topologies

VAC(in)

D1 D2

D3 D4 S1 S2

CB RL VO

LB1

LB2

+

-

D1 D2

D3 D4

LBVAC(in)

CB RL VO

+

-

VAC(in) LB

D1

D4

D2

D3

D5

D6

CB RL VO

+

-

S2

S1

600V/650V SiC diodes

Source: Emerson

4

Three phase PFC 5

Solar inverters topologies Pout < 4.6kW

VDCmax

VGRID

+ -

VDC/ 2

VDC/ 2

N

L

VDCmax

VDCmaxVDCmax

6

Solar inverter topologies Pout > 4.6kW

L1L2

L3

N

VDCmax = 1000V

N

AB

C

L1

L2

L3

VDC/ 2

VDC/ 2

N

VDCmax = 1000V

N

AB

C

L1

L2

L3

VDC/ 2

VDC/ 2

N

N

AB

C

VDCmax = 1000V

L1

L2

L3

VDC/ 2

VDC/ 2

N

N

VDCmax = 1000V

7

PFC working in continuous mode

Vmains = 85V

F=100kHz

dI/dt=400A/µs

POUT=1 000W

T°case = 100°C

VOUT= 400V

IL

IRM

TRANSISTOR

IL

IL+IRM

VOUT

High dI/dt

IT

VT

ID

VDQRR

EON(T)

EOFF(D)

24.2% 0.2%0.8%2.5%

72.4%

PrevD

PonDPoffD=0.62W

PcondD=6.01W

Pontr=17.9W

il

VOUT

Vmains

L Dboost

Vgate

IRM

Example STTH8R06D:

DIODE

8

Turn-off comparison versus TJ

VR=380V ; IF=8A; dI/dt=200A/us ; Tj=75°C

VR=380V ; IF=8A; dI/dt=200A/us ; Tj=125°C

Capacitive current of SiCdiodes

doesn’t increase with Tj

STTH8R06

STTH806TTI

SiC 8A

STTH8R06

STTH806TTI

SiC 8A

20ns / div

2A / div

20ns / div

2A / div

9

Power losses comparison versus dI/dt

Vmains=90V Pout=500W Tj=100°C

Fsw=100kHz

0123456789

101112131415161718

0 100 200 300 400 500 600 700 800 900

dI/dt (A/µS)

PO

NT

R (

W)

8A SiC diode

STTH806TTI

STTH8R06

10

Power losses comparison versus TJ

PFC Pout=500W Vmains=90V dI/dt=500A/µs F=100kHz

87.3

87.4

87.5

87.6

87.7

87.8

87.9

88

88.1

88.2

88.3

88.4

88.5

88.6

88.7

88.8

88.9

89

89.1

89.2

50 75 100 125 150 175Tj(°C)

Eff

icie

nc

y (

%)

8A TURBO2

8A TANDEM

6A SiC

8A SiC

11

αVF comparison between SiC

G1 and PN diodes

ST T HR8R06

0

5

10

15

20

25

30

35

40

45

50

0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5

VF(V)

IF(A

)

Pce7 25°

Pce7 125°

Pce7 150°

Tj ���� => VF ���� => Pcond ����

SiC 6A

0

5

10

15

20

25

30

0 1 2 3 4

VF(V)

IF(V

)

Tj=25°C

Tj=150°C

Tj=175°C

SiC=8A

ααααVF>0

ααααVF<0

PN diode: ααααVF<0 in the application area

Tj ���� => VF ���� => Pcond ���� => Tj ����

SiC diode: ααααVF>0 in the application area

Positive loop

Negative loop

12

Maximum forward current SiC G1 diodes

8A SiC IFSM = 30A,35A,40A,41A

Tj<175°C!

Tj>>Tjmax

13

Forward voltage comparison between G1 and

G2 (with JBS structure) SiC diodes

25°C

175°C

� VF=f(IF) versus Tj (tp=50µs)

75°C

125°C

STPSC606D 1G (SiC schottky)

STPSC6H065D 2G (SiC JBS) Thermal effect

14

Comparison of SiC diodes

with two JBS structures�VF=f(IF) versus Tj with (tp=50 µs)

25°C

225°C

Other JBS technoSTPSC6H065D 2G

75°C

125°C

175°C

15

Comparison of SiC diodes

with two JBS structure

STPSC6H065D

Other JBS techno

16

IFSM Comparison between G1

and G2 SiC diodes

1.E+01

1.E+02

1.E+03

1.E-05 1.E-04 1.E-03 1.E-02

IFSM(A)

tp(s)

Tc=25 °C

650V SiC 2G 600V SiC 1G

17

Critical phases in PFC application

AC in

Inrush phase:

Lightning surge test

IEC61000-4-5 :

Line drop-out test

EN 61000-4-11

VCout

Inrush resistor

- +

Bridge

Bypass diode

Boost diode

R=2Ώ

C

Bypass diode

ESR

Boost diode- +

Driver

PFC

2KV

C

Bypass diode

Boost

diode-

Driver

PFC

INT

C

18

Electro-thermal model of SiC diode

Thermal modelElectrical model

U1

TOPEN = 0.01

1

2

I3

IOFF = 0FREQ = 50IAMPL = 47

Dbreak

IN1

OUTIN2

R82

1

VF2

IN1

IN2

OUT

IF(V(%IN1)<V(%IN2), V(%IN1), V(%IN2))

(a+b*V(%IN1)+c*V(%IN1)*V(%IN1)+d*(V(%IN1))**3+e*(V(%IN1))**4)*(V(%IN2))

R80

1

(Vt1+aVt1*V(%IN1)+bVt1*V(%IN1)*V(%IN1))+(Rd1+aRd1*V(%IN1)+bRd1*V(%IN1)*V(%IN1))*V(%IN2)

VF1

OUT+

OUT-

IN

e1*(V(%IN)**4)+d1*(V(%IN)**3)+c1*V(%IN)*V(%IN)+b1*V(%IN)+a1

VF_tj_IF

R81

1

R77

1

(V(%IN1) *V(%IN2))

R83

1

VF3

VF11

(Vt3+aVt3*V(%IN1)+bVt3*V(%IN1)*V(%IN1)+cVt3*(V(%IN1))**3)+(Rd3+aRd3*V(%IN1)+bRd3*V(%IN1)*V(%IN1)+cRd3*(V(%IN1))**3)*V(%IN2)

PARAMETERS:

aRd1 = 2.1542E-04aVt1 = -6.4005E-04

bRd1 = 2.5860E-06bVt1 = -1.1968E-06

Vt1 = 9.7788E-01 Rd1 = 9.1267E-02

IN1

IN2

OUT

IF(V(%IN1)<V(%IN2), V(%IN1), V(%IN2))

TJ

PARAMETERS:

a1 = 1.3166E+00

b1 = 2.6601E-02

c1 = -2.2788E-04

d1 = 9.0534E-07

e1 = -1.3932E-09

PARAMETERS:

a = 8.8736E-02

b = -4.7201E-04

c = 3.0955E-06

d = -8.5670E-09

e = 8.4095E-12

PARAMETERS:

aRd3 = -4.3599E-04aVt3 = 1.4256E-02bRd3 = 2.3970E-06bVt3 = -7.8925E-05cRd3 = -4.1511E-09cVt3 = 1.3556E-07

Rd3 = 7.2948E-02Vt3 = 2.5132E+00

IFTC

R74

0.32484

R76

0.52881

R79

0.01547

C74

0.00118

C750.00053

C76

0.00311C77

0.00962

R84

0.27507

C78

0.03716

R85

0.19657

C79

0.20431

R86

0.10262

C80

0.74923

R87

0.02207

0

V2525

Tj

19

IFSM simulation

Time

0s 1ms 2ms 3ms 4ms 5ms 6ms 7ms 8ms 9ms 10ms1 V(Tj1g) V(TJ) 2 V(vfC) V(VF_tj_IF) 3 I(I6)

0V

100V

200V

300V

400V2

0V

5V

10V

15V2

>>0A

10A

20A

30A

40A

50A3

200°C ⇒⇒⇒⇒ Tj 2G

⇒⇒⇒⇒ Tj 1G >400°C

Thermal runaway

Phenomenon!IFSM 42A@Tc=25°C

VF typ 2G

VF typ 1G

20

Electro-thermal model of SiC diode

with PFC model

VB

Dbreak

D1

+

-

+

-

S2

SVON = 10VVOFF = 0.0V

V12

R3

2K IF(I(V13)>80,10,0)

V13

1Vac

0Vdc

V

V

V

V

I

V

V

I

V

I

VC

R78

0.6

R79

0.6

C53

0.5

IC = 90

C52

0.004

IC = 90

PARAMETERS:

AlphaVT0 = -0.0010324VT0 = 0.95982

Rd0 = 0.062574betaVT0 = -0.0000014857

deltaRd0 = 1.7401e-4etaRd0 = 1.5317e-6

V5

90

R4

1G

V7

90

R5

1G

TJ

(VT0+AlphaVT0*V(%IN1)+betaVT0*V(%IN1)*V(%IN1))+(Rd0+deltaRd0*V(%IN1)+etaRd0*V(%IN1)*V(%IN1))*V(%IN2)

vfC

R75

1

G3

0.000285*(PWR((300/(V(%IN+)+273)),(-0.7)))*DDT(V(%IN+, %IN-))

GVALUE

OUT+OUT-

IN+IN-R76

1 V8

90

9.363*(PWR((300/(V(%IN1)+273)),(1.2)))*(V(%IN1)-V(%IN2))(V(%IN1) *V(%IN2))

TJ3

G2

0.000344*(PWR((300/(V(%IN+)+273)),(-0.7)))*DDT(V(%IN+, %IN-))

GVALUE

OUT+OUT-

IN+IN-

TJ2

0

V9

40

R66

0.579

R67

0.6620

R68

0.3249

10.5258*(PWR((300/(V(%IN1)+273)),(1.2)))*(V(%IN1)-V(%IN2))11.936*(PWR((300/(V(%IN1)+273)),(1.2)))*(V(%IN1)-V(%IN2))

TJ4

C54

0.000521

C55

0.0020887

C56

0.021025

C57

0.401

R72

0.372

G4

0.000424*(PWR((300/(V(%IN+)+273)),(-0.7)))*DDT(V(%IN+, %IN-))

GVALUE

OUT+OUT-

IN+IN-

TJ

R6

1G(V(%IN1)-V(%IN2))*10

U2A

1

23

vm

C2

660u

IC = 127

L1

300uH

1 2R1

0.005

R2

1K

ABS

V1

FREQ = 60VAMPL = 127VOFF = 0

U1

RSFF

SE1

CLK2

RE3

Q4

Q5

E1

IF(V(%IN+, %IN-)>1,10,0)

EVALUE

OUT+OUT-

IN+IN-

E2

IF(V(%IN+, %IN-)>0,10,0)EVALUE

OUT+OUT-

IN+IN-

0.000002*(V(%IN1)*V(%IN2))

VA

V6

TD = 0.00001

TF = 0.0001PW = 0.15PER = 0.2

V1 = 0

TR = 0.02

V2 = 1

V4

TD = 0

TF = 0.003uPW = 1uPER = 10u

V1 = 0

TR = 0.003u

V2 = 10

0

E5

IF(V(%IN+, %IN-)<435,10,0)

EVALUE

OUT+OUT-

IN+IN-

VOUTR11

0.1

Diode model

PFC model

TjTcase

Heatsink

Equivalent model

Tamb

21

Start up simulation

Time

0s 20ms 40ms 60ms 80ms 100ms 120ms

1 V(TJ) 2 V(vfC)

80V

90V

100V

110V1

>>

0V

2.5V

5.0V2

I(R11)

0A

5A

10A

15A

20A

SEL>>

1 V(V12:+) 2 I(L1) 3 V(VOUT)

0V

0.5V

1.0V1

0A

5A

10A

15A

20A2

>>

0V

250V

500V3

• 8A G1 SiC , Vmains=90Vac, 60ms Soft Start, Ipk 13A, Cout=660uF, Fsw=100kHz, Tcase=90°C

Tj=101°°°°C

TC=90°°°°C

VFSiC

Vout

VSoftStart

IdSiC

Iline

10A

20A

15A

5A

0A

250V

500V

90√√√√2

0V

22

23

Time

0s 2ms 4ms 6ms 8ms 10ms 12ms 14ms 16ms 18ms 20ms1 V(TJ) 2 I(D2) 3 I(D3)

0V

100V

200V

300V1

0A

20A

40A

60A

80A2

0A

400A

800A3

SEL>>SEL>>

(7.1484m,214.85°C)

V(VOUT)200V

300V

400V

500V

Vout

Tc=50°C

IdSiCIdbypass

Line drop simulation with SiC G1 diode 23

24

Vout

Tc=50°C

IdSiCIdbypass

Time

0s 2ms 4ms 6ms 8ms 10ms 12ms 14ms 16ms 18ms 20ms1 V(TJ) 2 I(D2) 3 I(D3)

50V

100V

150V1

0A

20A

40A

60A

80A2

0A

400A

800A3

SEL>>SEL>>

(7.0892m,145.28°C)

V(VOUT)200V

300V

400V

500V

Line drop simulation with G2 SiC diodes24

Recommendations of Design

• Need to use a by-pass diode

• Cheec all critical phases (start-up phase, line drop-out, lightning surge test )

• Start-up phase: Increase the soft start time when it is possible

• Line drop-out phase (EN 61000-4-11): Limit the rising junction temperature with the use of the current limitation

• Lightning surge test (EN 61000-4-5): Don’t forget to check the test at 0°phase shift angle

• Choose the diode current rating to have Tj < Tjmax(175°C) during the transient phases.

25

Thank you!