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Yan Jiang Committee Members: Dr. Fred C. Lee (Chair) Dr. J. D. van Wyk

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Presentation on theme: "Yan Jiang Committee Members: Dr. Fred C. Lee (Chair) Dr. J. D. van Wyk"— Presentation transcript:

1 Three Dimensional Passive Integrated Electronic Ballast for Low Wattage HID lamps
Yan Jiang Committee Members: Dr. Fred C. Lee (Chair) Dr. J. D. van Wyk Dr. Dushan Boroyevich Dr. Shuo Wang Dr. William T. Baumann Dr. Carlos T. A. Suchicital January 27th, 2009

2 Low pressure discharge High (pressure) intensity discharge (HID)
Lighting 19% of global power consumption and 3% of global oil demand is attributable to lighting Incandescent Efficacy: 15~20 lm/W Life time: 1k~3k hours Standard Incand. halogen Gas discharge Solid State Low pressure discharge High (pressure) intensity discharge (HID) Fluorescent (FL) CFL CCFL Low pressure sodium Metal halide (MH) Ceramic MH Mercury vapor High pressure sodium LED Organic LED For FL and CFL, Technologies on both lamp and ballast are very mature. Simple and low cost ballast have been widely used in residential application and replacing the incandescent lamps. For HID lamps, mainly used in outdoor and high end, due to the large size and high cost of HID ballast. 60~200 lm/W 8k~18k hours 60~150 lm/W 8k~40k hours 40~160 lm/W 50k~60k hours

3 HID 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) 3

4 Need around 4 yr to break even
Track Lighting Halogen HID Lower efficacy Shorter lamp life (≈4kHr) ≈70% of market share Lower cost, smaller size (Basically incandescent lamp, doesn’t need ballast) 70W halogen≈20W HID Higher efficacy Longer lamp life (up to 20kHr) <20% of market share Higher cost, larger size (Needs sophisticated ballast) HID lamp system has higher initial cost, but is more energy efficient in long run. Track lights provide directable beams of high-quality light for use in retail displays, galleries, museums, and residences. They are useful in locations where lights need to be aimed at different angles and where the position of the light may be changed frequently. Until recently, the only light sources that could provide the right kind of illumination for track lighting were inefficient halogen lamps. However, the introduction of low-wattage, metal halide (MH) lamps in the mid-1990s gave designers and specifiers an energy-efficient alternative. These lamps not only reduce energy use but last several times longer than halogen lamps, thus leading to reduced lamp-replacement costs as well. However, costs for MH lamps and fixtures are significantly higher than those for incandescent units, so MH products are most cost-effective in applications with long burn hours and where changing lamps is difficult. Need around 4 yr to break even Market requirements for HID ballast: Compact size Low cost

5 Ballast for Gas Discharge Lamp
VS VAB VR Voltage (V) VAB Lamp R + VR - + VLamp - VLamp Current (A) ISS Ballast is needed to stabilize the current for gas discharge lamps fs>20kHz Like other gas discharge lamp as fluorescent lamp, HID lamp has negative VI characteristics as shown in this figure. So if an HID lamp can’t directly connected to a voltage source, a small variation of the current may lead to the extinguish or blow up of the lamp. Therefore, a ballast with a positive impedance is needed to compensate the negative impedance , and stabilize the lamp current. This is the first requirement for the HID lamp ballast. HID ballast should also provide a high ignition voltage pulse to start the lamp at the beginning. Provide a constant lamp power during the lamp lifetime. It also should provide a high PF and small input current harmonics, ballast should meet IEC Class C standard, which is the most stringent requirement especially for lighting application. Another special characteristic of HID lamp is a phenomenon called “acoustic resonance” . Acoustic resonance can occur when HID lamp is operating at high frequency from several kHz to several hundred kHz. And it will lead to the fluctuation of the light, variation of the color temperature, decrease the lamp lifetime and in the worst case even crack the discharge cube. The most effective way to eliminate AR is providing the lamp a low frequency square wave current. Since the HID lamp is has the highest efficacy and compact size, the ballast is also needed to have high efficiency and small size. L Lamp C High Q parallel-load series-resonant tank generate high voltage peak Transformer boost voltage pulse Ignitor is needed to initiate the gas discharge

6 From Magnetic to Electronic Ballast
Magnetic Ballast HF Electronic Ballast fs>20kHz L Ignitor Lamp L 110V/60Hz Lamp Higher cost Small and light Integrated ignitor No reignition, no flickering and audible noise With lamp power regulation (more intelligent) Improved lamp efficacy Simple, low cost, high reliability large and heavy External ignitor Reignition causes line frequency flickering No lamp power regulation HF electronic ballast greatly reduce the size and weight of ballast, and greatly improve the lamp performance

7 Most Significant Lighting Advance: CFL
. Most Significant Lighting Advance: CFL FL with magnetic ballast Typical CFL ballast circuit: Self-oscillating HB series resonant circuit * from Delta Compact fluorescent Compact fluorescent lamps (CFLs) are the most significant lighting advance developed for homes in recent years. They combine the efficiency of fluorescent lighting with the convenience and popularity of incandescent fixtures. CFLs can replace incandescents that are roughly three to four times their wattage, saving up to 75% of the initial lighting energy. Although CFLs cost from 10 to 15 times more than comparable incandescent bulbs, they also last 10 to 15 times as long. This energy savings and superior longevity make compact fluorescent lamps an excellent choice for residential use. As previously discussed, CFLs are one of the best energy efficiency investments available. When introduced in the early- to mid-1980s, CFLs were bulky, heavy, and too big for many incandescent fixtures. However, newer models with lighter electronic ballasts are only slightly larger than the incandescent lamps they replace. The new CFLs also produce a better color for the home. CFLs come in integral and modular designs. Integral CFLs have a ballast and a lamp in a single disposable unit. In CFL below 25 W, PFC and constant power control are not often used to achieve low cost CFL w/ built-in ballast Why this topology is not suitable for HID ballast?

8 HID lamp start-up profile
CFL v.s. HID CFL start up profile HID lamp 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 LF SQ AC current driving is needed to avoid Acoustic Resonance, additional LF inverter is needed. No Acoustic Resonance, can use HF AC current driving

9 Lamp voltage increase (due to AR) vs. freq.
Acoustic 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 Vlamp(V) fs(kHz) Detrimental effect of AR: Light lumens fluctuation Lamp color temperature variation Arc tube overheat Extinguish Lamp voltage increase (due to AR) vs. freq. Acoustic Resonance. At high frequency (f > 4 kHz) operation of HID lamps, standing pressure waves (acoustic resonances) can occur in the discharge tube. This phenomenon may lead to visible arc distortions, resulting in decreased lamp life time and, in some cases, cracking of the discharge tubes. Acoustic resonances are driven by periodic instantaneous lamp power. In conclusion it may be stated that the occurrence of acoustic resonances at high frequency can be considered as a limitation factor for a wide and reliable application of high frequency (< 60kHz) electronic ballasts supplying HID lamps . Acoustic Resonance is due to: Methods (for Ballast) to eliminate AR: Lamp frequency is within AR frequency band High frequency energy is larger than the AR threshold Operate in non-AR frequency Reduce HF energy to below the threshold * E. Rasch, Osram, 1988

10 Existing Methods to Eliminate AR_1
1. Operate in non-AR frequency DC Ultra HF 10kHz 20kHz 100kHz 200kHz AR AR-free 1) DC-type ballast (*S. Wada, 1987) Etching and asymmetrical eroding of electrodes due to cataphoretic effect 2) Operate at AR-free Zone (*E. Rasch, 1988) Difficult to select these windows due to dependency on lamp geometry and physical characteristics. 3) Operates at frequency higher than 300kHz (*R. Redl, 1999) High EMI caused by high frequency lamp arc.

11 Existing Methods to Eliminate AR_2
2. Reduce HF energy to below the threshold 1) Lamp Power spectrum spreading frequency modulation, phase-angle modulation… feedback modulation or random modulation Original Lamp voltage: Modulated Lamp voltage: 40dBV 20dBV 0dBV 0dBV Threshold varies due to lamp parameter inconsistency Possible to introduce AR on other frequency point * L. Laskai, 1998

12 Existing Methods to Eliminate AR-3
3. Square-wave current driving 1) Low Frequency Square Wave (LFSW) lamp current. (*Janos Melis, 1995) vlamp ilamp ≈x00Hz The only one used in commercial product Completely eliminate Acoustic Resonance, but has relatively complicated system structure. 2) High Frequency Square Wave (HFSW) lamp current. (*M. Ponce, APEC 2001) Flat instantaneous power ideally, due to parasitics, there is still HF energy provided to lamp

13 Requirements for HID Ballast
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: High power factor (PF>0.9) Small input current harmonics (IEC Class C and ITHD <10% ) EMI standard (FCC 18)

14 Typical Electronic HID Ballast
Achieve high PF, low ITHD Provide constant lamp power regulation Provide high ignition voltage Avoid Acoustic resonance(10K~500kHz) AC/DC PFC DC/DC Buck Regulated LF DC/AC Inv & Ignitor Unregulated Vin High PF, low ITHD Constant power Acoustic resonance free Low Crest Factor To compete with halogen and CFL in low wattage application, HID ballast need: Compact size Low cost Complicated circuit Low power density High cost

15 CHID Research Objective
A high power density, high performance, low cost solution for HID lamp ballast HID ballast Compact system architecture Novel circuit topology Built-in HID ballast CHID Novel integration technology 3D packaging scheme

16 Benchmark Discrete ballast Integrated ballast
Integrated Ignitor Integrated EMI filter Output filter

17 Dissertation 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 Ballast Topology Study,
Design and Implementation Investigation on system architecture for CHID ballast SSPFC AC/DC frond-end design Experimental verification

19 Three-stage HID Ballast Structure
LF SW Inv. & Ignitor Unregulated AC/DC PFC DC/DC Buck Vin Regulated Co L2 S2 For soft-start S1 B1 L1 Cb vin vlamp ilamp ≈400Hz S3 S4 S5 S6 Ignitor Lamp Here is a typical HID lamp ballast can meet the above requirements for HID lamp ballast. It is a three-stage structure. AC/DC PFC stage is to achieve high PF and small input current harmonics, DC/DC stage is to provide the lamp power regulation, buck is the simplest topology here. And DC/AC inverter/ignitor stage is an unregulated inverter to change the DC-link voltage/current to a low frequency square to avoid acoustic resonance. And also also provide high ignition voltage to start the lamp. High PF, low ITHD Constant power Acoustic resonance free Low Crest Factor Complicated circuit Low power density High cost *Janos Melis, 1995

20 From Three-stage to Two-stage Structure
Full-bridge Buck Converter with ignitor Vin AC/DC PFC DC/AC Inv. DC/DC & Ignitor BCM Regulated Unregulated S3 S4 S5 S6 Ignitor Lamp Co L2 S2 For soft-start S1 B1 L1 Cb vin S2 S3 S4 S5 Lo Co Lamp Lr Cr * 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

21 Two-stage HID Ballast_type A
*M. Sen, et al, IEEE transaction on IA, 2003 *J. Zhao, et al, IAS 2003 Boost Buck 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) 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

22 Two-stage HID Ballast_Type B
DC/DC DC/AC Inv. & Ignitor (Regulated) (Unregulated) AC/DC PFC Vin DC/AC Inv. & Ignitor (Regulated) (Unregulated) Single Stage PFC AC/DC Vin *Y. Yang, APEC 2005 *Y. Jiang, IAS 2000 SSPFC:DCM Boost + Flyback LF FB inv. 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 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.

23 Two-stage Structure Comparison
DC/AC Inv & Ignitor regulated Vin AC/DC PFC LF DC/AC Inv & Ignitor Unregulated Vin SSPFC AC/DC 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 DCM Boost type SSPFC: ITHD >10% High bus voltage(>Vin,pk) Need additional soft-start switch Only 1 High Freq. switch Simple 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

24 DCM Single Stage Single Switch PFC
DCM S2PFC is suitable for Low power application due to inherent PFC with simple control DCM PFC + DCM DC/DC: DCM PFC + CCM DC/DC: DC bus voltage is independent of load Higher current stress Small current stress Higher efficiency High voltage stress at light load * M. Madigan, etc, PESC’92

25 DCM S4PFC with DC Bus Voltage Feedback
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%) * F. Tsai etc. INTELEC’96

26 DCM Flyback + DCM Flyback *Jingrong Qian, Ph.D dissertation,
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 PFC: DCM PFC + DCM DC/DC Flyback DC/DC: large lamp load range (from open-circuit to short-circuit) DCM Flyback + DCM Flyback The main stream of S4PFC converter is based on two-cascade-stage PFC converter. It integrates PFC stage and DC/DC stage with a shared switch and its controller. Because the PFC semi-stage and dc/dc semi-stage share a common switch, only one control variable can be controlled. Since the output voltage is required to be regulated. It is required that PFC semi-stage has an inherent PFC function. . It is well known that a DCM boost or Flyback converter can draw a near sinusoidal input current with constant on-time control during a line period. Therefore, A DCM boost or flyback integrated with a dc/dc converter is able to achieve PFC and output regulation simultaneously with simple control. Good PFC Low DC bus voltage High current stress on the switch (only suitable for low power application) *Jingrong Qian, Ph.D dissertation,

27 Derivation of proposed SSPFC Converter
No isolation requirement DCM Flyback (PFC) DCM Buck-Boost (DC/DC) iav Vin, Unity PF and Low THD can be achieved at constant D and fs Constant Pout means constant D and fs

28 SSPFC AC/DC Front-end Benefits
+ Vb _ * Cb D2 L1a L1b * B1 D3 L2 Co RL S 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

29 Implementation Issues-1
Vgs IL2 Vb=120V VL2 * S1 D2 D3 B1 L2 Co RL L1a L1b Cb Vo Vo=90V D4 + - Vo,igi=300V - VD3 Since the inductor L2 operates in DCM, when the current through D3 reduced to zero, L2 will resonant with the junction capacitor of D3. If there is no damping, the voltage across L2, VL will reduced to -Vo, and the voltage across D3 will be 2Vo. Consider the load is open circuit, the output voltage is 300V, therefore 600V diode is not enough for the voltage rating. Therefore, Diode D4 is used to clamp VL at -Vb: when VL decreases to - Vb, D4 turns on, and the VL is clamped to - Vb, therefore the maximum voltage across D4 is Vb+Vo=450V. This clamp diode can also reduce the voltage stress of D2 and S1. In our design, this diode won’t work at normal operation mode. Therefore, this diode will not sacrifice the efficiency. + Vo+Vb Vo,igi+Vb High voltage stress on D3 due to voltage ringing when IL2 ignition mode (Vo=300V) VD3= -(Vo+VL2) ≈2Vo,igi

30 Implementation issue-2
D1 1b L D2 D3 * * * * irr of D1 + Vo - C C C b b b @ peak (vin > Vo) B1 Vin C o D4 L 2 S1 Large output voltage ripple due to the reverse recovery of D1 iD1 Irr of D1 Vo When switch turns off, D2 D3 will turn on, and if vin>Vo, D1 will see a reverse bias voltage. During the interval between the switch turn-off and D1’s turn off, a voltage of vin-vo is added to the leakage inductance and stray inductance of the loop of input-B1-L1_d1-D2-D3-Load. Which produce a large di/di.. Especially at high line input, the current through D1 before switch turns off is high, so this di/dt will introduce a large reverse recovery current through D1. Fortunately ,this reverse recovery occurs at switch turn-off, it will not add the switch current stress and switching loss, but it will increase the diode loss, and the This reverse recovery current flow through the load, which results in a large low frequency ripple in the output voltage. Irr of D1 iD3 Eliminate D1 Split S1 to two separate MOSFETs Solution:

31 Two-Switch Version of SSPFC Stage
L1a L1b D2 D3 * * * * S2 D4 Cb B1 S1 Co RL L2 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

32 Proposed HID Ballast Single stage PFC stage Inverter/Ignitor stage
fs=200kHz fs=400Hz Lr Cr Lamp S3 S4 S5 S6 KI KV PI PRef d Vo Io Function generator G2 G3 G4 G5 driver Comp. Iswi PWM IC MCU * 1a L 1b S1 D5 D6 S2 Vin L2 Co Cb Multiplier VVL VCL U.S. Patent 7,391,165 B2

33 Constant Power Control Scheme
VVL KIIo VCL KVVo multiplier PI Vcon Pref PO VO 50V 300V Control scheme Ideal ballast curve Current limiting mode: VCL* KIIO = Pref IO=Const. Constant power mode: KIIO* KVVO = Pref VOIO=Const. Voltage limiting mode: VVL* KVVO = Pref VO=Const.

34 Inverter/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 90V fs=400Hz Ignition Mode Steady state

35 Experimental Results – I
PF>99.5%, ITHD<10% @ Vin=120Vac +/-10%

36 Experimental Results-II
Vlamp Ilamp Low bulk cap voltage at all load conditions Bulk cap voltage is lower than vin,pk Vo=89V, Po=19.9W Efficiency = 84.7%(w/o control power) Efficiency  81.3%(with control power)

37 Experimental Results – III
Constant power regulation during steady state Current limiting during start-up Voltage limiting before ignition

38 Power Density 2.4W/in3 4.5W/in3 6.0W/in3 (1.8x) (2.5x)
Benchmark: Commercial 20W HID ballast New commercial product CPES Prototype Use same circuit topology 2.4W/in3 4.5W/in3 (1.8x) 6.0W/in3 (2.5x)


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