ee155/255 green electronics - stanford...

EE155/255 Green Electronics

Power Circuits10/4/17

Prof. William DallyComputer Systems Laboratory

Stanford University

Course Logistics• HW2 due Monday 10/9• Lab groups have been formed• Lab1 signed off this week• Lab2 out

EE155/255 Lecture 4 - Power Circuits

Course at a GlanceNo Date Topic HWout HWin Labout Labck Lab HW

1 9/25/17 Intro(basicconverters) 1 1 IntrotoST32F3 PeriodicSteadyState2 9/27/17 EmbeddedProg/PowerElect.3 10/2/17 PowerElectronics-1(switches) 2 1 2 1 ACEnergyMeter PowerDevices4 10/4/17 PowerElectronics-2(circuits)5 10/9/17 Photovoltaics 3 2 3 2 PVMPPT MotorcontrolMatlab6 10/11/17 FeedbackControl7 10/16/17 ElectricMotors 4 3 4 3 Motorcontrol-Lab/ Feedback8 10/18/17 IsolatedConverters9 10/23/17 SolarDay 5/PP 4 5 4 PS IsolatedConverters10 10/25/17 Magnetics11 10/30/17 SoftSwitching 6 5/PP 6 5 Magnetics MagneticsandInverters12 11/1/17 ProjectDiscussions13 11/6/17 Inverters,Grid,PF,andBatteries 6 P 6 Project14 11/8/17 Thermal&EMI15 11/13/17 QuizReview C116 11/15/17 Grounding,andDebuggingQ 11/15/17 Quiz-intheevening

11/20/17 ThanksgivingBreak C211/22/17 ThanksgivingBreak

17 11/27/17 Wrapup18 11/29/17 GuestLecture C319 12/4/17 GuestLecture20 12/6/17 NoClass

TBD Projectpresentations P12/15/17 Projectwebpagedue


Test SetupMulti-Level PV System


Prim

ary

and

Seco

ndar

y PC

Bs


Course to Date• We need sustainable energy systems• At the core they are voltage converters• Periodic steady-state analysis, buck and boost• Intelligent control + power path• Intelligent control done with event-driven embedded software• Real devices have switching and conduction loss – and parasitics


Last Time• DC and AC characteristics of MOSFETs, Diodes, and IGBTs• Switches in pairs• One switch does the work• Turn on transient• Diode reverse recovery• Parasitics• Gate drive and Miller capacitance


Turn-On and Turn-Off Loss


Turn-On Loss


IP

ILQRR QD

ID

VDS

s

t1 t2 t3

Turn-OffBuck with Diode

Excess current charges drain node.

Integrate to get switching energy

E =VDDtr16IL +

13I1

!

"#

$

%&

ID

VDS

IL

trtc

I1


Turn-OffBuck with Diode

If current ramps faster than voltage nearly ZVSID

VDS

IL

tr

tc

V1

E = 16V1ILtc


Parasitic Losses

LP

C2

CL

L1D1

M1

C1


Gate Drive


Gate Driver

RGH

RGL

M1

source

drain

Control &Protection+

-VGH

in

Gate-driver IC

SH

SL


Effect of Miller Cap on Rise Time

M1

iG

CDG


Effect of Miller Cap on Rise Time

M1

iG

CDG

dVDdt

=iGCDG

Δt = ΔVDCDG

iG

Example: i = 0.5A, C = 100pF, DV = 400V


Bootstrap Supply

M1

i

M2

V1

+-

High-SideGate Drive

Low-SideGate Drive

VGL

+-

inH

inL

GND

X

G1

G2

CB

RB DB V


Dead Time


Too Little Dead Time (11.6kW loss)

1.6µs 1.7µs 1.8µs 1.9µs 2.0µs 2.1µs 2.2µs 2.3µs 2.4µs 2.5µs 2.6µs 2.7µs 2.8µs 2.9µs 3.0µs 3.1µs 3.2µs-5V

0V

5V

10V

15V

20V

25V

30V

35V

40V

45V

50V0V

2V

4V

6V

8V

10V

12V

14V

16V-3.0KA

-2.5KA

-2.0KA

-1.5KA

-1.0KA

-0.5KA

0.0KA

0.5KA

1.0KA

1.5KA

2.0KA

2.5KA

3.0KA-10KW

0KW

10KW

20KW

30KW

40KW

50KW

60KW

70KW

80KW

90KW

100KW

110KW

V(m1)

V(p1l) v(p1h)-v(m1) V(1:gl) V(1:gh)-v(m1)

Ix(1:h:1) Ix(1:l:3)

ix(1:h:1)*(v(d)-v(m1)) ix(1:l:1)*v(m1)

4mJ3.4mJ

2500A

3.4mJ3.7mJ


0.6 0.8 1 1.2 1.4 1.6 1.8v G

(V)

0

10

0.6 0.8 1 1.2 1.4 1.6 1.8

v X (V

)

0

20

40

0.6 0.8 1 1.2 1.4 1.6 1.8

i M1 (k

A)

0

1

2

3

t (µ s)0.6 0.8 1 1.2 1.4 1.6 1.8

P M1 (k

W)

0

50

100

0

5

10

15

0

5

10

15

The “Real” Gate Signal


Too Much Dead-Time (340W loss)(Still pretty good)


0V

5V

10V

15V

20V

25V

30V

35V

40V

45V

50V-2V

0V

2V

4V

6V

8V

10V

12V

14V

16V-700A

-600A

-500A-400A

-300A

-200A

-100A

0A100A

200A

300A

400A

500A600A

700A

800A-4KW

0KW

4KW

8KW

12KW

16KW

20KW

24KW

28KW

32KW

36KW

40KW

V(m2)

V(p2l) V(p2h)-v(m2) V(2:gl) V(2:gh)-v(m2)

Ix(2:h:1) Ix(2:l:3)

ix(2:h:1)*(v(d)-v(m2)) ix(2:l:1)*v(m2)

700mV diode drop

740A

0.27mJ


Just Right (310W loss)


0V

5V

10V

15V

20V

25V

30V

35V

40V

45V

50V-2V

0V

2V

4V

6V

8V

10V

12V

14V

16V-350A

-280A

-210A

-140A

-70A

0A

70A

140A

210A

280A

350A

420A-0.3KW

0.0KW

0.3KW

0.6KW

0.9KW

1.2KW

1.5KW

1.8KW

2.1KW

2.4KW

2.7KW

V(m4)

V(p4l) v(p4h)-v(m4) v(4:gh)-v(m4) V(4:gl)

Ix(4:h:1) Ix(4:l:3)

IX(4:l:1)*v(m4) ix(4:h:1)*(v(d)-v(m1))

0.19mJ3uJ

Conduction loss is I2R = 502 x 1m ~ 25W

Slower gate rise

Short duration diode drop


Too much dead time is better than too little


Snubbers


LD

G 50V

+-

40A

RS

CS

D

Cj

M

Dampen Ringing Nodes

LD and Cj resonate when M is on

Parallel RS dampens tank

Series CS limits dissipation


Inductance on Drain

8uJ turn-on

42uJ turn-off


With Snubber (1nF, 5W)

8uJ turn-on

2uJ in snubber

42uJ turn-off


LD

G 50V

+-

40A

RS

CS

D

Cj

M

Design Procedure

Pick RS ~ 1/wCj

Pick CS so t >= p/w

OrEs = CSV2/2


Example Cycle


IGBT Half Bridge


VS+-

GD

QH

QL

CCGH

GD

CCGL

DH

DL

SL

X

CH

RX

CX

IL

LSL

LS

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

50

i QH

(A)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2−20

0

20

40

i DL (A

)

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 20

100

200

300

400

v x (V)

t (µs)

0

200

400

v CEH

(V)

One Switching Cycle


1

2

Turn-On Transient


60 80 100 120 140 160 1800

50

i QH

(A)

60 80 100 120 140 160 180−20

0

20

40

i DL (A

)

60 80 100 120 140 160 1800

200

400

v X (V)

60 80 100 120 140 160 180390

400

410

v CH

(V)

60 80 100 120 140 160 180−10−5

05

1015

v GEH

(V)

t (ns)

0

200

400

v CEH

(V)

−20

0

20

40

i QL (A

)

0

10

20

P QH

(kW

)

−10−5051015

v GEL

(V)

1 2

2

𝐸~60𝑛𝑠×22𝑘𝑊

2 = 660µ𝐽

𝐸 = 773µ𝐽

𝐿𝑑𝑖𝑑𝑡

Hig

h-Si

de T

urn

On


Hig

h-Si

de T

urn

Off

1.55 1.6 1.65 1.7 1.750

20

40

i QH

(A)

1.55 1.6 1.65 1.7 1.750

10

20

30

40

i DL (A

)

1.55 1.6 1.65 1.7 1.750

200

400v X (V

)

1.55 1.6 1.65 1.7 1.75

400

405

410

415

v CH (V

)

t (µs)

0

200

400

v CEH

(V)

0

2

4

6

8

P QH

(kW

) 𝐸 = 230𝜇𝐽

𝐿𝑑𝑖𝑑𝑡

1

2

Lab Half-Bridge Module


The Half-Bridge Module

1

2

Hin

IRS21834

ComVss

LO

S

HO

COM

Out

VDVB

M1

M2

R14.7

R24.7

U1

��

VCC

3

DT

GND

4

Hin

��

V12

C14.7 F

2.2 F200V

D356V5W

D1

R3 1

C21 F

VBCSupply

VDCFilter

D215V

C3

7

6

5

13

12

11


Bootstrap Supply

1

2

Hin

IRS21834

ComVss

LO

S

HO

COM

Out

VDVB

M1

M2

R14.7

R24.7

U1

��

VCC

3

DT

GND

4

Hin

��

V12

C14.7 F

2.2 F200V

D356V5W

D1

R3 1

C21 F

VBCSupply

VDCFilter

D215V

C3

7

6

5

13

12

11


Bootstrap Supply


Drain Voltage Filter

1

2

Hin

IRS21834

ComVss

LO

S

HO

COM

Out

VDVB

M1

M2

R14.7

R24.7

U1

��

VCC

3

DT

GND

4

Hin

��

V12

C14.7 F

2.2 F200V

D356V5W

D1

R3 1

C21 F

VBCSupply

VDCFilter

D215V

C3

7

6

5

13

12

11


Drain Voltage Filter300nH Input Inductance


SPICE


SPICE Example – A Voltage Doubler


A Voltage Doubler* Simple voltage "doubler".include "gel.lib".param td=100n tr=100n tf=100n tw=2.5u tcy=5u ncy=2.param l1=22uH c1=10uF r1=10

* call half-bridge subcircuitxhb vd mid g g 0 v12 gel_hb

* circuitl1 vin mid {l1}c1 vd 0 {c1}r1 vd 0 {r1}

* suppliesv12 v12 0 12vin vin 0 24

* stimulusVG g 0 PULSE(0 5 {td} {tr} {tf} {tw} {tcy} {ncy})

.ic i(l1)=9.2

.ic v(vd)=42.8

.tran {ncy*tcy}


Turn-On Transient


Steady State


Close up of Drain Current


With PID Control


A Warning• SPICE (or any simulator) is a Verification tool, not a Design tool• Design your circuit first

– Use Excel, Matlab, a calculator etc… to calculate component values• Then simulate your circuit to check operation and fine-tune parameters• Don’t try to design your circuit using SPICE

• Simulation is not a substitute for thinking


Summary of Power Circuits• Real switches have limitations

– Conduction losses (RON for FETs, VCE for IGBTs, Diode drop)– Switching losses (finite ton, toff, trr)

• With current source load, current ramps, then voltage falls • And voltage rises before current falls• May be dominated by reverse recovery time• Complicated by inductance

– Parasitic L and C• Power MOSFETs

– Switch quickly, have linear I-V, integral diode• IGBTs

– Diode-like I-V, slower switching• Diodes

– Have reverse recovery time• Switches operate in pairs

– For one-way converters, one switch may be a diode– Synchronous rectification – make both switches FETs to reduce loss– Need “dead time” to avoid “shoot through” current

• Gate-drive circuits control rise and fall times– Supply Miller capacitance

• Bootstrap supply needed for high-side driver• Snubbers dampen voltage and current transients• Use SPICE as a verification tool, not a design tool


Course at a GlanceNo Date Topic HWout HWin Labout Labck Lab HW

1 9/25/17 Intro(basicconverters) 1 1 IntrotoST32F3 PeriodicSteadyState2 9/27/17 EmbeddedProg/PowerElect.3 10/2/17 PowerElectronics-1(switches) 2 1 2 1 ACEnergyMeter PowerDevices4 10/4/17 PowerElectronics-2(circuits)5 10/9/17 Photovoltaics 3 2 3 2 PVMPPT MotorcontrolMatlab6 10/11/17 FeedbackControl7 10/16/17 ElectricMotors 4 3 4 3 Motorcontrol-Lab/ Feedback8 10/18/17 IsolatedConverters9 10/23/17 SolarDay 5/PP 4 5 4 PS IsolatedConverters10 10/25/17 Magnetics11 10/30/17 SoftSwitching 6 5/PP 6 5 Magnetics MagneticsandInverters12 11/1/17 ProjectDiscussions13 11/6/17 Inverters,Grid,PF,andBatteries 6 P 6 Project14 11/8/17 Thermal&EMI15 11/13/17 QuizReview C116 11/15/17 Grounding,andDebuggingQ 11/15/17 Quiz-intheevening

11/20/17 ThanksgivingBreak C211/22/17 ThanksgivingBreak

17 11/27/17 Wrapup18 11/29/17 GuestLecture C319 12/4/17 GuestLecture20 12/6/17 NoClass

TBD Projectpresentations P12/15/17 Projectwebpagedue


ee155/255 green electronics - stanford...

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