Three Dimensional Passive Integrated Three Dimensional Passive Integrated Electronic Ballast for Low Wattage HID lampsElectronic Ballast for Low Wattage HID lamps

Yan JiangYan Jiang

Committee Members: Committee Members:

Dr. Fred C. Lee (Chair)Dr. Fred C. Lee (Chair)

Dr. J. D. van WykDr. J. D. van Wyk

Dr. Dushan BoroyevichDr. Dushan Boroyevich

Dr. Shuo WangDr. Shuo Wang

Dr. William T. BaumannDr. William T. Baumann

Dr. Carlos T. A. SuchicitalDr. Carlos T. A. Suchicital

January 27th, 2009

2Lighting

19%19% of of global power consumptionglobal power consumption and and 3%3% of of global oil demandglobal oil demand is attributable to lighting is attributable to lighting

Fluorescent (FL)

CFL

CCFL

Low pressure sodium

Metal halide (MH)

Ceramic MH

Mercury vapor

High pressure sodium

60~200 lm/W

8k~18k hours

60~150 lm/W

8k~40k hours

IncandescentIncandescent

Efficacy: 15~20 lm/W

Life time: 1k~3k hours

Standard Incand.

halogen

Gas dischargeGas discharge Solid StateSolid State

Low pressure discharge

High (pressure) intensity discharge

(HID)LED

Organic LED

40~160 lm/W

50k~60k hours

3HID Applications

Track lighting for offices and retail environment (20W~39W)

Automotive headlights (35W~70W)

LCD projectors (100W~150W)

Supermarket lighting (175W~400W)

Stadium, parking area and roadway/tunnel lighting (400W~2000W)

4Track Lighting

Halogen HID

Lower efficacy

Shorter lamp life (≈4kHr)

≈70% of market share

Lower cost, smaller size

(Basically incandescent lamp, doesn’t need ballast)

Higher efficacy

Longer lamp life (up to 20kHr)

<20% of market share

Higher cost, larger size

(Needs sophisticated ballast)

70W halogen≈20W HID

HID lamp system has higher initial cost, but is more energy efficient in long run.

Need around 4 yr to break even

Compact size

Low cost

Market requirements for HID ballast:

5Ballast for Gas Discharge Lamp

Current (A)

Vo

ltag

e (V

)

VLamp

VR

VAB

LampR

+ VR - + VLamp -

+ VAB -

VS

ISS

Ignitor is needed to initiate the gas discharge

Ballast is needed to stabilize the current for gas discharge lamps

fs>20kHz

L Lamp

C

High Q parallel-load series-resonant tank generate high voltage peakTransformer boost voltage pulse

6From Magnetic to Electronic Ballast

Lamp110V/60Hz

Magnetic Ballast

L

Ignitor

fs>20kHz

L

HF Electronic Ballast

Lamp

Simple, low cost, high reliability

large and heavy

External ignitor

Reignition causes line frequency

flickering

No lamp power regulation

Higher cost

Small and light

Integrated ignitor

No reignition, no flickering and audible

noise

With lamp power regulation (more

intelligent)

Improved lamp efficacy

HF electronic ballast greatly reduce the size and weight of ballast, and greatly improve the lamp performance

7Most Significant Lighting Advance: CFL

Typical CFL ballast circuit:

Self-oscillating HB series resonant circuit

* from Delta

CFL w/ built-in ballast

FL with magnetic ballast

Why this topology is not suitable for HID ballast?

..

In CFL below 25 W, PFC and constant power control are not often used to achieve low cost

8CFL v.s. HID

HID lamp start-up profileCFL start up profile

Requires lower ignition voltage: 400V~600V, Series resonant parallel loaded circuit is enough

Requires much higher ignition voltage: 1kV~5kV (cold strike), ~20KV (hot strike), Voltage need to be further boosted by transformer or else

No Acoustic Resonance, can use HF AC current driving

LF SQ AC current driving is needed to avoid Acoustic Resonance, additional LF inverter is needed.

9Acoustic Resonance

Acoustic Resonance in HID lamps:

standing pressure waves occur on the discharge tube at high frequency (f>4kHz)Normal arc Arc with AR

10 20 100 200

70

80

90

100

Vlamp(V)

fs(kHz)

Lamp voltage increase (due to AR) vs. freq.

Detrimental effect of AR:

Light lumens fluctuation

Lamp color temperature variation

Arc tube overheat

Extinguish

* E. Rasch, Osram, 1988

1. Lamp frequency is within AR frequency band

2. High frequency energy is larger than the AR threshold

Acoustic Resonance is due to:

1. Operate in non-AR frequency

2. Reduce HF energy to below the threshold

Methods (for Ballast) to eliminate AR:

10

3) Operates at frequency higher than 300kHz (*R. Redl, 1999)

High EMI caused by high frequency lamp arc.

Existing Methods to Eliminate AR_1

1. Operate in non-AR frequency1. Operate in non-AR frequency

Difficult to select these windows due to dependency on lamp geometry and physical characteristics.

1) DC-type ballast (*S. Wada, 1987)

2) Operate at AR-free Zone (*E. Rasch, 1988)

Etching and asymmetrical eroding of electrodes due to cataphoretic effect

10kHz 20kHz 200kHz100kHz

AR AR-free

DC Ultra HF

11

1) Lamp Power spectrum spreading

frequency modulation, phase-angle modulation…

feedback modulation or random modulation

Threshold varies due to lamp parameter inconsistency Possible to introduce AR on other frequency point

* L. Laskai, 1998

Existing Methods to Eliminate AR_2

2. Reduce HF energy to below the threshold2. Reduce HF energy to below the threshold

)cos()( tAtv sOriginal Lamp voltage:

Modulated Lamp voltage:

))cos(cos()( tttAtv msm mm f

f

Graph0

dB

(v/H

z)

-40.0

-20.0

0.0

20.0

f(Hz)

10.0k 15.0k 20.0k 25.0k 30.0k 35.0k 40.0k 45.0k 50.0k

dB(v/Hz) : f(Hz)

vlamp

Graph0

dB

(v/H

z)

-40.0

-20.0

0.0

20.0

40.0

f(Hz)

27.5k 30.0k 32.5k 35.0k

dB(v/Hz) : f(Hz)

vlamp

5 50

40dBV

0dBV

20dBV

0dBV

12

1) Low Frequency Square Wave (LFSW) lamp current. (*Janos Melis, 1995)

Existing Methods to Eliminate AR-3

Completely eliminate Acoustic Resonance,but has relatively complicated system structure.

2) High Frequency Square Wave (HFSW) lamp current. (*M. Ponce, APEC 2001)

3. Square-wave current driving3. Square-wave current driving

The only one used in commercial product

Flat instantaneous power ideally, due to parasitics, there is still HF energy provided to lamp

vlamp

ilamp

≈x00Hz

13Requirements for HID Ballast

High power factor (PF>0.9)

Small input current harmonics (IEC 61000-3-2 Class C and ITHD <10% )

EMI standard (FCC 18)

Functions:

Stabilize lamp current

Provide high voltage (several kV) pulse for initial starting

Acoustic resonance free (LF SW AC current driving)

Constant lamp power regulation (maximize lamp life time)

Regulations:

14Typical Electronic HID Ballast Achieve high PF, low ITHD

Provide constant lamp power regulation

Provide high ignition voltage Avoid Acoustic resonance(10K~500kHz)

LF DC/AC Inv& Ignitor

UnregulatedVin

AC/DCPFC

DC/DCBuck

Regulated

S3

S4

S5

S6

LampCo

L2S2

For soft-start

S1B1

L1

Cbvin Lr

Cr

vlamp

ilamp

≈400Hz

Compact size

Low cost

To compete with halogen and CFL in low wattage application, HID ballast need:

Complicated circuit

Low power density

High cost

High PF, low ITHD

Constant power

Acoustic resonance free

Low Crest Factor

15Research Objective

A high power density, high performance, low cost solution for HID lamp ballast

HID ballast

Built-in HID ballast

Compact system architecture

Novel circuit topology

Novel integration technology

3D packaging scheme

16

Discrete ballastBenchmark Integrated ballast

Output filter

Integrated Ignitor

Integrated EMI filter

17Dissertation Outline

Chapter 1: Introduction

Chapter 2: High Density HID Ballast Topology Study, Design and

Implementation

Chapter 3: High Density 3D Passive Integrated Ballast

Chapter 4: Thermal Modeling, Management and Experimental

Verification for Integrated Ballast

Chapter 5: Conclusions and Future Work

18

Chapter 2: High Density HID BallastChapter 2: High Density HID Ballast Topology Study,Topology Study,

Design and ImplementationDesign and Implementation

Investigation on system architecture for CHID ballast

SSPFC AC/DC frond-end design

Experimental verification

19

AC/DCPFC

Three-stage HID Ballast Structure

Complicated circuit

Low power density

High cost

High PF, low ITHD

Constant power

Acoustic resonance free

Low Crest Factor

LF SW Inv.& Ignitor

UnregulatedVin

DC/DCBuck

Regulated

S3

S4

S5

S6

Ignitor

LampCo

L2

S2

For soft-start

S1B1

L1

Cbvin

vlamp

ilamp

≈400Hz

*Janos Melis, 1995

20

S2

S3

S4

S5

VLMP

DC/DCDC/AC Inv.& Ignitor

Regulated Unregulated

AC/DCPFC

Vin Full-bridge Buck Converterwith ignitor

S3

S4

S5

S6

Ignitor

LampCo

L2S2

For soft-start

S1B1

L1

Cbvin

S2

S3

S4

S5

Lo

Co

LampLr

Cr

From Three-stage to Two-stage Structure

BCM

* U.S. patent 5,932,976, MEW

20W MH ballast (2.4W/in3)

Save 1 switch and controller

BCM Boost-type PFC: unity PF, ITHD<10%,

High VB(>Vin,pk), need additional soft-start switch

3 HF switches

Need complicated sensing circuit for constant power control

21Two-stage HID Ballast_type A

*M. Sen, et al, IEEE transaction on IA, 2003

Boost

Save 1 switch and controller

BCM Boost-type PFC: unity PF, low ITHD, High bus voltage(>Vin,pk), need soft-start switch

3 HF switches

Only constant current control is achieved (also need complicated sensing circuit for constant power control)

Boost Boost PFCPFC

Boost Boost PFCPFC

*J. Zhao, et al, IAS 2003

Buck Boost Save 3 switches

BCM Boost-type PFC: unity PF, low ITHD

High bus voltage(>Vin,pk), Need soft-start switch

3 HF switches

Only constant current control is achieved

Large Cs, Lamp voltage or duty cycle is limited by the Vdc and Vcs

22Two-stage HID Ballast_Type B

*Y. Jiang, IAS 2000

DC/DC DC/AC Inv.& Ignitor

(Regulated) (Unregulated)

AC/DCPFCVin

DC/AC Inv.& Ignitor

(Regulated) (Unregulated)

Single Stage PFC AC/DCVin

DCM Boost type PFC: ITHD>10% , High bus voltage(>Vin,pk), need additional soft start switch

only 1 HF switch, but with higher current stress

SSPFC:DCM Boost + Flyback LF FB inv.

*Y. Yang, APEC 2005

DCM Boost type PFC: ITHD>10%, High bus voltage(>Vin,pk), need additional soft start switch,

only 1 HF switch, but with higher current stress

Save 2 LF switch, but adding passive component: one L winding, one C, and one diode.

23Two-stage Structure Comparison

DC/AC Inv& Ignitor

regulated

Vin

AC/DCPFC

BCM Boost type PFC:

unity PF, ITHD <10% ,

High bus voltage(>Vin,pk),

Need additional-soft start switch

3 High Freq. switches

Complex sensing and control

Specific requirements of SSPFC for Low-wattage HID Ballast:

Stringent input current harmonic requirement (ITHD<10%)

Low bulk cap voltage under large load range (open-circuit to short-circuit)

Load characteristic: constant power regulation , large output voltage range.

No isolation requirement

LF DC/AC Inv& Ignitor

Unregulated

Vin

SSPFCAC/DC

DCM Boost type SSPFC:

ITHD >10%

High bus voltage(>Vin,pk)

Need additional soft-start switch

Only 1 High Freq. switch

Simple control

24DCM Single Stage Single Switch PFC

* M. Madigan, etc, PESC’92

Small current stress

Higher efficiency

High voltage stress at light load

DC bus voltage is independent of load

Higher current stress

DCM PFC + DCM DC/DC: DCM PFC + CCM DC/DC:

DCM S2PFC is suitable for Low power application due to inherent PFC with simple control

Combine PFC with DC/DC

BV

oVgv

25DCM S4PFC with DC Bus Voltage Feedback

* F. Tsai etc. INTELEC’96

Reduce the bulk cap voltage stress

Reduce the switch current stress

THD increase due to the dead time in input current (much larger than 10%)

26DCM PFC +DCM DC/DC

*Jingrong Qian, Ph.D dissertation,

Good PFC

Low DC bus voltage

High current stress on the switch (only suitable for low power application)

DCM Flyback + DCM FlybackDCM Flyback + DCM Flyback

Flyback PFC:Flyback PFC:DCM PFC

+ DCM DC/DC

• Low bus voltage stress

• lTHD <10%• Unity PF, Low ITHD (<10%)

• Low and adjustable bus voltage

• Easy soft start

Flyback DC/DC:Flyback DC/DC: • large lamp load range (from open-circuit to short-circuit)

27Derivation of proposed SSPFC Converter

DCM Flyback (PFC)

sa1

2in

av fL2

DVi

iav Vin, Unity PF and Low THD can be achieved at constant D and fs

sa1

22pkin

in fL4

DVP

DCM Buck-Boost (DC/DC)

s2

22b

out fL2

DVP

Constant Pout means constant D and fs

L1a

*

S

RL

*

L1b Cb

D1

L1a

*

S

RL

*

L1b Cb

D1

D3

L2

Cb

SCo RL

D3

L2

Cb

SCo RL

No isolation requirement

28SSPFC AC/DC Front-end

RL

*

S

B1

*

L2

CbD2

D1

D3

Co

L1a L1b

DCM Flyback DCM Buck-Boost

Benefits Automatic unity PF and very low THD (<10%)

Constant and low bulk cap voltage at all load conditions

Simple duty cycle control, constant power regulation

Easy soft start, no additional sw needed

pa

b VL

LV

1

2

2

+Vb

_

29

* ***

S1

D2 D3

B1L2

Co RL

L1a L1b

Cb

Implementation Issues-1

*

S

B1

*

L1

L2

Cb

D2D1

D3

Co RL

L1a L1b

*

S

B1

*

L1

L2

Cb

D2D1

D3

Co RL

L1a L1b

High voltage stress on D3 due to voltage ringing when IL2 =0 @ ignition mode (Vo=300V)

VL2

IL2

VD3

Vb=120V

Vo=90V

Vo+Vb

Vo

VD3= -(Vo+VL2)

Vo,igi=300V

≈2Vo,igi

Vo,igi+Vb

+

-

+ -

Vgs

D4

30Implementation issue-2

Eliminate D1

Split S1 to two separate MOSFETs

Large output voltage ripple due to the reverse recovery of D1

* *

Cb

Cb

**1a1aL1a 1b1bL1b

L222

Cb

S1

Cooo

D1 D2 D3

B1D4

Vin

+

Vo

-

irr of D1

iD1

Irr of D1

Irr of D1

iD3

Vo

@ peak

(vin > Vo)

Solution:Solution:

31Two-Switch Version of SSPFC Stage

Benefits:

Reduce the output voltage ripple (by eliminating the reverse recovery current of D1)

Remove the clamping diode D4 by using the body diode of S2

Change 1 Mosfet to 2 smaller Mosfet (share the same gate signal), save 2 diodes

Separate the power loss into two switches. S1.S2 can use smaller package (IPAK) and no heat sink is needed

S2

* ***

S1

D2 D3

B1L2

Co RL

L1a L1b

Cb

D4

32Proposed HID Ballast

Lr

Cr

LampS3

S4

S5

S6

KI KV

10oVoI VKIK

W

PI

PRef

d

VoIo

Function generator

G2 G3 G4 G5

driver driver

Comp.

Iswi

PWM IC MCU

* ***1a1aL1a 1b1bL1b

S1

D5 D6

S2

Vin L2Co

Cb

Multiplier

VVL VCL

Single stage PFC stage Inverter/Ignitor stage

fs=200kHz fs=400Hz

U.S. Patent 7,391,165 B2

33Constant Power Control Scheme

VVL

KIIo

VCL

KVVo

multiplier PI Vcon

Pref

Current limiting mode: VCL* KIIO = Pref IO=Const.

Constant power mode: KIIO* KVVO = Pref VOIO=Const.

Voltage limiting mode: VVL* KVVO = Pref VO=Const.

Control scheme

PO

VO50V 300V

Ideal ballast curve

34Inverter/Ignitor

Steady state:

fs=400Hz, D=0.5

Ignition mode:

fs=100~200kHz(sweeping), D=0.5

3rd harmonic resonance is used to reduce the size of Lr (fr=450kHz)

Auto-transformer structure is used to reduce the voltage across the cap

Lr

Cr

LampVBus

S1

S4S2

S3

1:1.5

Lr

Cr

LampVBus

S1

S4S2

S3

1:1.5

Ignition Mode Steady state

90V

fs=400Hz

35Experimental Results – I

PF>99.5%, ITHD<10%

@ Vin=120Vac +/-10%

95

96

97

98

99

100

105 110 115 120 125 130 135

Vin(V)

PF(%)

5

7

9

11

13

15

THD(%)

PF THD

vin

iinVin: 50V/div

Iin: 0.2A/div

2ms/div

vin

iinVin: 50V/div

Iin: 0.2A/div

2ms/div

Input Current Harmonics

0

5

10

15

20

25

30

35

3 5 7 9 11 13 15 17 19

In/I1(%)

IEC 61000-3-2 Class C

measured results

Input Current Harmonics

0

5

10

15

20

25

30

35

3 5 7 9 11 13 15 17 19

In/I1(%)

IEC 61000-3-2 Class C

measured results

Input Current Harmonics

0

5

10

15

20

25

30

35

3 5 7 9 11 13 15 17 19

In/I1(%)

IEC 61000-3-2 Class C

measured results

36Experimental Results-II

Vo=89V, Po=19.9W

Efficiency = 84.7%(w/o control power)

Efficiency 81.3%(with control

power)

Vlamp

Ilamp

Low bulk cap voltage at all load conditions

Bulk cap voltage is lower than vin,pk

vin

iin

020406080100120140160

0 50 100 150 200 250 300

Vout(V)

Vb(V)

vin

iin

020406080100120140160

0 50 100 150 200 250 300

Vout(V)

Vb(V)

37Experimental Results – III

0

5

10

15

20

25

0 100 200 300

Vout (V)

Pout (W ) Pout

Current limiting Voltage limiting

fs decreasing

Constant power

Lamp operation

area

0

5

10

15

20

25

0 100 200 300

Vout (V)

Pout (W ) Pout

Current limiting Voltage limiting

fs decreasing

Constant power

Lamp operation

area

Constant power regulation during steady state

Current limiting during start-up

Voltage limiting before ignition

38Power Density

CPES PrototypeBenchmark: Commercial 20W HID ballast

2.4W/in3 4.5W/in3

(1.8x)

New commercial product

6.0W/in3

(2.5x)

Use same circuit topology