(12) United States Patent

Transcription

1 (12) United State Patent USOO B2 (10) Patent No.: US 9.462,666 B2 Pickett et al. (45) Date of Patent: Oct. 4, 2016 (54) ELECTRODELESS FLUORESCENT (52) U.S. Cl. BALLAST DRIVING CIRCUIT AND CPC... H05B 4I/282 ( ); H05B 41/38 RESONANCE CIRCUIT WITH AIDDED ( ) FILTRATION AND PROTECTION (71) Applicant: Environmental Potential, Paadena, CA (US) (72) Inventor: Andrew C Pickett, Paadena, CA (US); Naveen R Tera, Sandy, UT (US); Robert V Rawling, Sandy, UT (US) (73) Aignee: ENVIRONMENTAL POTENTIALS, Paadena, CA (US) (*) Notice: Subject to any diclaimer, the term of thi patent i extended or adjuted under 35 U.S.C. 154(b) by 0 day. (21) Appl. No.: 14/828,815 (22) Filed: Aug. 18, 2015 (65) Prior Publication Data US 2016/ A1 Feb. 25, 2016 Related U.S. Application Data (60) Proviional application No. 62/039,372, filed on Aug. 19, (51) Int. Cl. H05B 3700 ( ) H05B 39/00 ( ) H05B 4L/4 ( ) H05B 4I/282 ( ) H05B 4L/38 ( ) (58) Field of Claification Search None See application file for complete earch hitory. (56) Reference Cited 5,767,631 A * 6,441,652 B1* U.S. PATENT DOCUMENTS 6/1998 Konopka et al ,307 8/2002 Qian ,108 6,486,570 B1* 11/2002 Price et al. r 307/ A1* Parra et al / / A1* 5, 2014 Gocha et al ,85 * cited by examiner Primary Examiner Anh Tran (74) Attorney, Agent, or Firm Buchalter Nemer (57) ABSTRACT A ballat circuit for a lighting ytem uing an induction fluorecent lamp utilize an AC-DC rectification circuit, a DC-DC boot power converion circuit, a DC-AC half bridge inverter circuit, and a reonating circuit to ignite the lamp and maintain Subtantially contant power output of the lamp, while the DC-AC half bridge inverter circuit i further compried of a gate iolation tranformer connected in a half bridge inverter chematic which ue a ballat integrated circuit (IC) to drive a high ide MOSFET and a low ide MOSFET and the gate iolation tranformer elec trically iolate a gate ignal to the high ide MOSFET. 9 Claim, 11 Drawing Sheet

2 U.S. Patent Oct. 4, 2016 Sheet 1 of 11 I 0], H. zzzzzzzzzzzzzzzzzzzzzzzzzzzzzz???????????????????????*********{}? /

3 U.S. Patent Oct. 4, 2016 Sheet 2 of 11 ************************? **** #*** 858

4

5 U.S. Patent Oct. 4, 2016 Sheet 4 of 11 US 9.462,666 B2 * r r or r n or r or r or r or rr Y ??? «*****! } ---- {X} ~... Ç ; ~~~); }

6 U.S. Patent Oct. 4, 2016 Sheet S of 11??????????????????????????????????ºzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz) zzzzzzzzzzzzzzz}???????????????????????????????????????r??????????????????????????????????

7

8 U.S. Patent Oct. 4, 2016 Sheet 7 of 11 US 9.462,666 B2

9 U.S. Patent Oct. 4, 2016 Sheet 8 of 11

10 U.S. Patent S.

11 U.S. Patent Oct. 4, 2016 Sheet 10 of 11 Low eqeey

12 U.S. Patent S r - tudo?!» ~~~~)

13 1. ELECTRODELESS FLUORESCENT BALLAST DRIVING CIRCUIT AND RESONANCE CIRCUIT WITH AIDDED FILTRATION AND PROTECTION CROSS REFERENCE TO RELATED APPLICATIONS Thi application i a non-proviional application which claim priority from U.S. Ser. No. 62/039,372, filed Aug. 19, 2014, the dicloure of which i pecifically incorporated by reference herein. TECHNICAL FIELD OF THE INVENTION Thi invention relate to lighting of electrodele/induc tion fluorecent lamp. BACKGROUND Fluorecent lamp have been widely ued in indutry in recent year due to their higher efficiency and longer life than electric bulb. While conventional fluorecent lamp have electrode, induction fluorecent lamp do not ue any electrode for their operation. A lighting ytem uing an induction fluorecent lamp conit of an inductively coupled electrodele fluorecent lamp along with it driving ballat. The principal of electromagnetic induction i employed in the lamp ytem to ignite the plama, making the plama to emit light on the fluorecent wall of the tube. Since the lamp ytem doe not contain any electrode, the life of electrodele lamp i ignificantly higher than typical fluorecent lamp. The nature of thee lamp i that they require higher ignition frequency to ignite and higher oper ating frequency to maintain contant light output. Thee frequencie are in radio frequency range. While elf-ocil lating reonating circuit are often ued in thee ballat, they are not power factor corrected or efficient. Self-ocil lating circuit are very enitive to variation in the compo nent and they are not very well uited for high temperature application. Due to the feature of low maintenance and higher life time, electrodele lamp are often intalled in high bay, tunnel, high ceiling and other location where air circulation and ventilation i very minimal and, due to thi, the lamp and ballat are ubjected to extreme high temperature condition. Poor fixture deign alo add more heat to the lamp-ballat ytem. Extreme heat condition due to environmental ue factor will vary the lamp and ballat parameter, uch a lamp inductance and ballat operational characteritic. Therefore, it i extremely important to have a lamp-ballat ytem that can withtand higher tempera ture, while maintaining it good power quality. SUMMARY OF THE INVENTION The preent invention i generally directed to way to improve a ballat circuit ued with an electrodele induc tion fluorecent bulb. Thi invention relate to an operating circuit for an electrodele induction fluorecent lamp. The electronic ballat for an electrodele induction lamp conit of AC DC rectification, power factor correction while the rectified DC i booted, DC-AC inverion uing half bridge truc tured MOSFET, ballat reonating circuit to ignite the lamp and to maintain the lamp output, and common mode and differential mode filter for thi circuit. Electrodele induc tion fluorecent lamp are unique in their nature, and they require much higher frequency of operation compared to traditional fluorecent lamp. While ome of the electrode le ballat run at 1.25 MHz and 235 khz, running fre quency of 200 khz i meaured to be optimum for election of reonating inductor and capacitor, to maintain continuou operation and retrike in the event of high ambient tempera ture. Selection of ballat IC (chip) that can run under thee frequency condition with high power requirement i nearly impoible, due to their limitation on handling electrical tre. To overcome the electrical tre problem and make the IC run at higher power, higher frequency condition, and an iolated high ide gate tranformer i employed in the circuit. Thi invention dicue about the gate drive iola tion circuit along with the unique reonating condition of the ballat circuit. Thi invention alo dicue about add ing waveform correction circuit to the ballat circuit in order to filter the noie and protect the circuit under harh elec trical condition. Accordingly, it i an object of the preent invention to provide improved ballat circuit ueful with an electrode le induction fluorecent bulb. Thi and further object and advantage will be apparent to thoe killed in the art in connection with the drawing and the detailed decription of the invention et forth below. BRIEF DESCRIPTION OF THE FIGURES FIG. 1 i a block diagram of a ballat circuit for a lighting ytem uing an induction fluorecent lamp according to the preent invention. FIG. 2 i a chematic diagram of a DC-DC Power Factor Correction circuit that i repreented by block 100 in FIG. 1. FIG. 3 i a chematic diagram of a DC-AC Half Bridge Inverter circuit that i repreented by block 60 in FIG. 1. FIG. 4 i a chematic diagram of a Reonance Circuit that i repreented by block 70 in FIG. 1. FIG. 5 illutrate a waveform correction filter uch a i dicloed in U.S. Pat. No. 7, that i repreented by block 50 in FIG. 1. FIG. 6 illutrate a baic ballat IC circuit deign for a typical lighting application. FIG. 7 i a chematic diagram of the high ide driver circuit from FIG. 9. FIG. 8 i a waveform achieved from FIG. 7 in actual operation. FIG. 9 i a chematic diagram of block 60 in FIG. 1 in greater detail than et forth in FIG. 3. FIG. 10 illutrate a typical Q-curve for a conventional electronic-fluorecent lamp ballat while FIG. 11 illutrate how high temperature hift operating point on the Q-curve of FIG. 10. FIG. 12 illutrate the high energy actually meaured in the reonating tank of a conventional electrodele-fluore cent lamp during tartup at high temperature while FIG. 13 illutrate how idealized ballat waveform hould look during tartup at high temperature. FIG. 14 illutrate a Q-curve obtained by actual meaure ment of a circuit deigned in accordance with the preent invention while FIG. 15 illutrate actual waveform of the ame circuit obtainer during tartup at high temperature. DETAILED DESCRIPTION OF THE INVENTION FIG. 1 give a block diagram of a ballat circuit ueful in the preent invention that include AC-DC rectification uing diode bridge 90, DC-DC boot power converion

14 3 along with power factor correction 100, DC-AC inverion uing half bridge inverter circuit 60, and reonating circuit 70 to ignite the lamp and maintain the contant power output of the lamp. The ballat circuit i protected with common mode, differential mode filter 80 and alo a waveform correction circuit 50 i added in parallel to the circuit for an added protection and performance. FIG. 2 how the DC-DC boot ection of the ballat circuit of FIG. 1 along with active power factor correction. Integrated circuit STL i ued in tranition mode operation, with a MOSFET 102 witch and boot inductor 105 in traditional boot topology, to achieve booted DC at 103 from the rectified DC 104 with corrected power factor of 0.99 and low THD level. Low lo boot inductor 105 i ued in thi boot topology. Electrolytic capacitor 106 i choen Such that it can handle maximum ripple current at maximum temperature condition for longer life time. FIG. 3 how the DC-AC inverter ection of the ballat circuit of FIG. 1 employ two MOSFET witche 1 and 20 in half bridge reonant inverter model. Integrated circuit IR i ued to drive the two MOSFET 1 and 20 in the circuit. Gate iolation tranformer 7 i ued to iolate the high ide gate, connected from HO pin 18 and V 34. Clamping Zener 3 and 4 are connected acro MOSFET 1 to enure the Voltage at 10 doen't exceed clamping Voltage of Zener. Low ide MOSFET 20 i connected from Lo 41, through bia reitor 42. FIG. 4 how the reonant circuit of the ballat circuit of FIG. 1, which comprie blocking capacitor 23, reonating inductor 24, and reonating capacitor 25 along with elec trodele lamp 26. FIG. 5 how waveform correction technology 51 added in parallel to the ytem. The preent invention mainly deal with the ection waveform correction 50, DC-AC half bridge inverter circuit 60 and reonating circuit 70 of the ballat circuit mentioned in FIG. 1. Detailed Decription of the DC-AC Inverion Circuit: FIG. 6 illutrate a baic ballat IC circuit deign for a typical lighting application. Thi circuit ue ballat IC 28 to drive high ide MOSFET 1 and low ide MOSFET 20, witching booted DC from terminal 21. Baed on the internal gate driving circuitry of the IC, the high ide witche from terminal 33 and 34 and output the ignal at 35. So, the ignal i actually 35 referenced to 34, and i fed to gate 10 of high ide MOSFET 1 through gate bia reitor 37. In order to turn on MOSFET 1, voltage at gate 10 need to be greater than voltage at 11, and o pin 35 i alway higher than pin 34. Low ide MOSFET 20 receive it gate ignal from low ide drive output 41 of IC 28 through it bia reitor 42. When the IC i powered up, it generate the gate ignal 41 for low ide MOSFET 20, turning it on. At thi point, the high ide MOSFET 1 i till off, and the path of current i from regulated DC (ued to power the IC) 39, boot diode 31, boottrap capacitor 32 and then low ide MOSFET 20. Thi way boottrap capacitor 32 i charged to one diode dropped to regulated DC voltage value. IC then generate the high ide ignal 35, hutting down it low ide ignal 41. Thi high ide ignal i of amplitude at 33 (one diode dropped to regulated DC voltage) will turn on the high ide MOSFET 1. Once both the Switche 1 and 20 tart ocillat ing, terminal 11 will ee the booted DC a high a 450 VDC. In thi condition, in order to turn on high ide MOSFET 1, the added boottrap voltage from boottrap capacitor (regulated DC 39-diode drop 31) to the 450 VDC will uccefully turn on the high ide MOSFET 1. Thi way of uing the IC to drive the two MOSFETS in half bridge configuration i Succeful for mot of the fluorecent light ing application that run at le than 60 khz. However, the configuration of FIG. 6 i not realitic when dealing with higher frequency of operation along with higher wattage application. High energy or high Voltage hort duration tranient reulting from the reonating tank in the ballat circuit at 11 may eventually be tranferred to IC 28 through high ide 37 or low ide 42, adding witching tranient from MOSFET 1 and 20 due to faulty ignal, cauing early life termination or permanent damage of IC 28. Thee typical ballat IC are deigned to withtand a maximum of 60 khz for it preheat while induction lighting require 466 khz a preheat frequency. Therefore, thee IC' are not uitable for higher frequency higher wattage appli cation. However, there are no or limited reource for IC' that can operate under higher wattage higher frequency application and thi leave an engineer no choice other than uing the exiting technology to drive higher energy appli cation. Electrodele lamp have a weet pot of 250 khz for reonance and 200 KHZ a their operational frequency. The above IC' available in the market are not ueful to drive the Electrodele lamp application, unle ome other addition to the circuit are made. The preent invention eek to ue mot typical fluore cent ballat IC to run high frequency, higher energy elec trodele lamp reliably and efficiently. A mentioned in the lat paragraph, the main reaon for the IC to be damaged i the maive energy tranfer from the reonating tank to the IC' drive circuitry. In order to olve thi problem, iolation of the gate ignal i achieved. Although gate iolation can be implemented at both the high ide and the low ide of the bridge, it i epecially deirable to iolate jut the high ide of the bridge becaue only the high ide of the bridge carrie higher energy and uing one iolation circuit intead of two ave pace and cot of PCB. Implementation of High Side Gate Tranformer: In order to run the circuit at higher wattage and higher frequencie, the traditional ballat IC circuit need further modification, and an iolation gate tranformer will allevi ate ome of the tre. The added advantage of thi tran former i that it electrically iolate the MOSFET from the control circuitry. Driver circuit 14 from FIG. 7 conit of coupling capacitor 15, 1:1 iolation tranformer 7, diode 5. biaing reitor 6, clamping Zener diode 3 and 4. N-channel MOSFET 1, and pull down reitor 2. FIG. 7 illutrate the high ide driver circuit chematic ueful in the preent invention. Coupling capacitor 15 i placed in erie between the HO ignal 18 and the dotted ide primary ide of the tranformer 17. The other end of primary ide of the tranformer 8 i connected to ground 19. Diode 5 i connected acro gate reitor 6, connecting it anode to dotted econdary 16 of the tranformer 7 and it cathode to gate 10 of MOSFET 1 and/or anode of Zener 3 and/or gate-ource reitor 2. Reitor 2 i connected acro gate 10 and ource 11 of N-channel MOSFET 1. Reitor 2, cathode of Zener 4 i connected to undotted end of econdary 9 tranformer 7. Undotted end econdary ide 9 of the tranformer 7 i connected to the ource 11 of the MOSFET 1. The winding ratio of tranformer 7 i 1:1 and the input and output ignal are in phae (oberve the dot at 16 and 17). In an idealitic condition, a tranformer doen't tore any energy. But, in reality, leakage inductance and magnetizing inductance in the tranformer tore a little energy and thi caue low efficient tranformer deign that can affect the turn on and turn off timing of the gate ignal. Therefore, it i very important to have the tranformer deigned with low

15 5 leakage inductance. Gate driver output high ide gate ignal at 18 with repect to 19, with 19 being connected to digital ground. Coupling capacitor 15 i connected in erie with the primary winding of the iolation tranformer 7 in order to block any DC voltage while paing the AC portion of HO ignal 18 to the dotted primary ide of the tranformer 17. Tranformer 7 will aturate, if coupling capacitor 15 i not ued in erie with the winding, therefore coupling capaci tor 15 reet the Voltage for the magnetizing inductance. When the HO ignal 18 i poitive, it will induce poitive voltage at dotted terminal 16 of tranformer 7, bia gate reitor 6 allow the current flow to the gate 10 of N-channel MOSFET 1, bypaing diode 5. Diode 5 i a blocking diode during the poitive Voltage ignal at 16, and the gate current only pae through gate reitor 6. When the gate ignal goe to Zero at 16, diode 5 help to dicharge the gate capacitance of the MOSFET 1 quickly, bypaing the gate reitor 6, pull down the gate 10 to ource voltage 11, o that the MOSFET 1 i properly turned off efficiently and quickly. Bia gate reitor 6 i ued to avoid any gate tranient current from uncoupled inductance at 16 reaching MOSFET' 1 gate 10. Clamping Zener diode 3 and 4 are ued to make Sure that the gate Voltage doen't exceed the pecified Voltage range, clamping the Voltage at 13 to rail to rail voltage of 16V. In other word, thee two Zener 3 and 4 clip the negative and poitive Swing from the looely coupled econdary inductance related tranient. Pull down reitor 2 i ued to diipate Voltage tranient (dv/dt) caued by looely coupled econdary inductance from econdary wind ing 16 and 9 of the tranformer 7. During witching tranition uncoupled econdary inductance at 13 may create voltage pike that can puncture MOSFET gate' 10 oxide layer, thu permanently damaging the MOSFET 1. MOS FET uually fail in hort circuit mode and thu the two MOSFET in half bridge may conduct at the ame reulting in fue and/or current ene reitor blow out. Therefore, it i eential to have the pull down reitor 2 between gate and ource of the MOSFET, to protect the MOSFET from Voltage tranient. Coupling capacitor 15 provide AC cou pling and thu the level hift for gate drive ignal 18. After adding Zener 3 and 4 and coupling capacitor 15 from FIG. 7 at the high ide MOSFET 1, gate 10 i now driven by -V. and V-V, a oppoed to 0 and Voi, where Vc i the voltage acro coupling capacitor 15, and V i the gate Voltage. Thee waveform are hown in FIG.8. By doing o, the FET receive negative bia during it turn off time and hence it improve the turn off peed. It alo improve the dv/dt immunity of the MOSFET. Pull down reitor 2 from FIG. 7 pull the gate low during turn on, o that FET i alway off at tart up. Pull down reitor 2 help the blocking capacitor to charge and dicharge, otherwie Voltage never build up acro blocking cap. Temperature Dependency of the Circuit: A mentioned above, electrodele lamp ytem are often intalled at high bay and tunnel with very low air circu lation and ventilation. Under thee circumtance, the ballat ytem doen t have very good thermal tranfer outide the fixture, and they mut therefore withtand high tempera ture. The ambient temperature of the electrodele lamp ytem under thee condition may go up to 180 F., cauing the ballat component to run at above 200 F. Component value under thee extreme high temperature vary quite a bit, altering the circuit operating condition. A the value of thee component change, reonating condition of the cir cuit alo change, hifting the reonance frequency higher or lower than deigned. However, the IC i deigned to drive the FET at preprogrammed dead time and frequency, and any variance in the reonating frequency might not ignite the lamp. A the lamp i not ignited, the ballat IC keep trying to retrike the lamp reetting it value, a lot of energy might flow in the reonating circuit. There i a chance that thi energy will take the path of the high ide MOSFET to the ballat IC, damaging the internal driver circuit of the IC. The gate driver iolation will prevent thi caue of the damage to the IC, electrically iolating the gate ignal to the control ignal. Therefore, the gate iolation tranformer i ued in the ballat circuit to enhance the MOSFET control mechanim, protect the MOSFET from voltage tranient, iolate the control circuitry from noie, alleviate the electrical tre on ICS internal driver circuit, and reduce Switching loe at MOSFET. Reonating Circuit 70: From FIG.9, MOSFET 1 and 20 are connected in a totem pole, half bridge configuration circuit and driven from high ide and low ide gate ignal from IC 28. Control circuit 29 determine the dead time, witching frequencie of the IC 28. MOSFET Switch the booted DC at terminal 21 and 22. The reonating tank from FIG. 4 conit of DC blocking capacitor 23, reonating inductor 24 and reonating capaci tor 25. Electrodele fluorecent lamp 26 i connected in parallel with the reonating capacitor 25. MOSFET 20 i connected to ground through current ening reitor 27. Current ene reitor 27 limit the current that i being driven in the reonating tank 30. The value of reonating capacitor 25 i maller than DC blocking capacitor 23, o that lamp 26 get the higher AC voltage during it initial trike. Lower capacitor 25 will alway have higher voltage compared DC blocking capacitor 23. Once lamp 26 trike, the lamp will have le impedance compared to reonating capacitor 25 and hence the reonance capacitor behave like an open circuit, making capacitor 23 and inductor 24 alone in the reonating tank 30. Thi will change reonating condition in the tank, reulting in change of frequency for operation and change of Voltage. Electrodele lamp do not have any electrode or filament in them, o they don t require preheat condition, meaning electrodele lamp do not require time to preheat and preheat current. The ballat IC ha programmable preheat time, and preheat frequency, ballat i made to operate very hort duration of time 140 ms for preheat with preheat frequency of 466 khz. Before the lamp i ignited, the erie L-C circuit will be in reonance with high Q factor. Once the preheat mode i paed, the frequency i wept (decreaed) toward the reonance and the lamp Voltage increae up to kv to ignite the lamp. Once thi high Voltage ignite the lamp, the circuit then become a erie L and parallel R C with low Q factor. After ignition, the frequency in the circuit i further decreaed to running frequency of the lamp, and the lamp current i maintained at contant value at it running frequency. The preent invention addree preheat frequency, pre heat time and reonating condition of the ballat circuit. The value of the circuit parameter hould be choen in Such a way that the ballat trike the lamp Succefully at all temperature condition irrepective of the variance in it component value. Electrodele lamp are uually run at 235 khz with a preheat frequency and reonating frequency of 450 khz and 240 khz repectively. FIG. 10 how the typical Q-curve for an electronic-fluorecent lamp ballat. In thi figure, the ballat initially follow the high Q charac teritic 125 of the reonating tank, and the ballat weep from preheat frequency 121 through Ignition frequency 122, where the ballat ignite the lamp. Once the lamp i ignited,

16 7 the operating frequency of the circuit drop to running frequency 123, where the circuit maintain low Q value graph 126. The reonating condition of the circuit are maintained at reonating frequency 124. In thee typical characteritic of the reonating tank, there i ignificant difference between reonating frequency 124 and running frequency 123, ay at leat 30 khz. However, due to the variance in the value of reonating inductor and lamp inductance under high temperature, the difference between the reonating frequency and running frequency move fur ther cloer in le than 10 khz range, and the Q-curve of the lamp ytem hift a hown in FIG. 11. In thi figure, the running frequency 129 of the ballat ytem i very cloe to the reonating frequency 128 of the tank, and the lamp run cloe to reonance frequency. By the nature of reonance, the tank hold a lot of energy and maximum power tranfer during reonating condition, and hence the ballat will be dealing with exceive power and energy while it run. Thi will tre the ret of the electrical component in the circuit and further caue damage to the ballat IC 28, cauing permanent damage to the ballat. Thi i the main reaon behind the failure of electronic ballat in the field intalla tion when they are ubjected to high temperature. Ballat will motly fail when they are power cycled at thee high temperature. Thi i a challenging deign iue in electrode le fluorecent ballat and it i reported that mot of the ballat failure in the field intallation are caued by thi deign error. The deign error common in exiting deign i that the frequencie choen for the ballat are very cloe to each other. FIG. 12 how the high energy in the reonating tank during tartup at high temperature. The preheat time for the ballat i approximately 400 m 132, with a 750V ignition voltage 133 at 400 m. The ballat maintain the preheat voltage of 700V 130 and 0.4. A 131 for 400 ms 132. Thi would calculate to 280 W of preheat energy in the reonating tank before even the lamp i ignited. It i een that the ballat circuit i facing exceive energy while it trie to light the lamp. Thi i an exceive energy that doen t need to be generated during ignition of the lamp. FIG. 13 how the typical lamp characteritic during normal temperature con dition. Preheat voltage 135 hould be le than the running voltage 137, and the preheat current 138 hould be zero before the ignition voltage 136. Once the lamp i ignited 136, the value of running voltage 137 and running current 139 hould be maintained contant and teady throughout the lamp operation. For an efficient and Succeful operation of ballat under high temperature, the ballat waveform hould look like FIG. 13, but not like FIG. 12. In the preent invention, the value of reonating inductor and capacitor are choen in Such a way that the Q-curve doen t hift a lot for any temperature variance. The value of reonant tank are choen taking into account of variance in inductor, capacitor and lamp inductance value with repect to temperature change. Variance in the lamp induc tance alo occur due to the different manufacturing tech nique adopted by lamp manufacturer. Therefore it i very important to deign a reonating tank that can light the lamp at all poible condition. IC 28, blocking capacitor 23, reonating inductor 24, reonating capacitor 25, and the lamp inductance 26 from FIG. 9 were extenively tudied under different temperature condition, with varying oper ating and preheat frequencie, and the bet poible combi nation of operating point are drawn in FIG. 14. From FIG. 14, the value of preheat 141, reonance 144, and running frequency 143 of the ballat have been choen to be 466 khz, 231 khz and 199 khz. Thee value are teted to be lighting the lamp at high temperature Succefully, and maintaining the contant lamp lumen output throughout it operation. The running frequency 143 i choen uch a way that it not cloe to the reonance frequency 144 and of parametric variance will not lead the ballat to run at reonating frequency under any condition. Therefore, the ballat avoid maive energy and/or power tranfer while it run. Thi change of Q-curve will caue le tre to the ret of the ballat component, and hence will lat longer with optimum performance. Thi new et of value will alo help the ballat to retrike uccefully at extreme tempera ture condition. FIG. 15 how the ucceful lamp trike at high temperature. From thi figure, it i een that the reonating tank doen t hold any energy while it ignite the lamp. The value of preheat voltage 146 i 200V while the preheat current 149 i negligible during the preheat time of 110 ms 151. The lamp ha an ideal ignition voltage of 900V 147, and after ignition voltage 148 and current 150 are teady and contant throughout the operation of the lamp and therefore the lamp output i contant. FIG. 15 i mea Sured at higher temperature condition and it i oberved that the operating condition of the ballat are very cloe to the idealitic condition of the ballat from FIG. 13. The ballat i teted for it accuracy and robutne for retrike at the higher temperature a well. Ballat wa kept at ambient temperature of 85 C. and went through 34,000 power cycle. Ambient operating temperature of 85 C., caued all the electrical component in the ballat circuit to exceed their maximum temperature limit, however the ballat i oberved to be power cycled 34,000 time uccefully with low THD and high power factor. Therefore, ue of high ide gate iolation tranformer, optimized tank circuit value and the frequency of operation are three important parameter for the ucceful efficient operation of electrodele induc tion ballat at all operating temperature. Waveform Correction Circuit: The lat part of thi invention deal with waveform correction & TVSS protection 50 of FIG. 1. Thi invention introduce waveform correction technology to the ballat technology to maintain good power quality, along with added protection feature. Electrodele ballat are operating under radio frequency range (up to 466 khz during preheat, and 199 KHZ run frequency), and a traditional differential and common mode filter may not be adequate to remove the noie generated from the ballat circuit. Heavy ballat intallation location including freeway and tunnel will require further filtration, uch that the noie generated from the ballat will not affect the enitive electronic equipment Such a traffic controller, Surveillance camera, communi cation networking ytem. Senitive electronic equipment Such a traffic control ytem, Smart lighting control, com munication ytem, and IP camera are highly Suceptible to frequency noie generated by nonlinear load Such a light ing panel. Frequency noie in the range of 1.5 khz to 1 MHz need to be filtered from the load panel before they caue malfunction or erratic behavior of the enitive com puterized load. Ballat circuit alo need to be protected from internal/external generated electrical noie when intalled in the field. Therefore, the ballat need a filtration circuit along with a protection circuit for it ucceful operation in the field. Conducted or radiated energy tranfer due to the electronic ballat on to the main line need to be filtered, proceed and protected. Waveform correction tech nology mentioned in U.S. Pat. No. 6,486,570B1 ha been ued and implemented in the ballat circuit a hown in FIG. 5.

17 9 In Summary, and without meant to be limiting or exhau tive, the preent invention dicloe the following concept and idea: 1. From FIG. 9, high ide gate iolation tranformer 7 hould be connected in halfbridge inverter chematic, in the application of electrodele induction ballat for the purpoe of reducing electrical tre on typical ballat IC 28 internal driver circuit, o that ballat IC 28 can run at higher frequencie (466 khz) than it pecification of 60 khz. 2. From FIG. 9, high ide gate iolation tranformer 7 hould be connected in halfbridge inverter chematic, in the application of electrodele induction ballat for the purpoe of iolating and protecting the high ide MOSFET gate 1, and hence the MOSFET 10 in the event of operating ballat at higher frequencie and higher temperature. 3. From FIG. 9, high ide gate iolation tranformer 7 hould be connected in halfbridge inverter chematic, in the application of electrodele induction ballat for the purpoe of protecting the ballat IC 28, in the event of operating ballat at higher frequencie and higher temperature. 4. From FIG. 14, the Q-curve of the electrodele induc tion lamp-ballat ytem hould be hifted uch a way that the difference between reonance and running frequency i much higher (at leat greater than 30 khz) when the ballat i under high ambient operating temperature condition. Thi would decreae the preheat energy in the reonating tank, and hence Succeful retrike of the lamp at higher temperature. 5. The reonating circuit value, operating frequency for the ballat IC hould be choen taking into temperature dependence on parameter value at 85 C. 6. From FIG. 14, preheat, reonance and running fre quency of electrodele induction lamp i choen at 466t5 khz, khz and 1995 khz repectively. Thee value are choen after careful reearch of temperature dependence on component value in the circuit. 7. The waveform correction circuit mentioned in U.S. Pat. No. 6,486,570B1 i added to the ballat filtering circuit in order to remove electrical noie generated from ballat to the line. 8. The waveform correction circuit mentioned in U.S. Pat. No. 6,486,570B1, the dicloure of which i pecifically incorporated herein in it entirety by reference, i added to the ballat to protect the ballat from internal/external tran ient from the facility. While the invention ha been decribed herein with ref erence to certain preferred embodiment, thoe embodi ment have been preented by way of example only, and not to limit the cope of the invention. Additional embodiment thereof will be obviou to thoe killed in the art having the benefit of thi detailed decription. Accordingly, it will be apparent to thoe killed in the art that till further change and modification in the actual concept decribed herein can readily be made without departing from the pirit and cope of the dicloed inven tion. What i claimed i: 1. A ballat circuit for a lighting ytem uing an induction fluorecent lamp, compriing: an AC-DC rectification circuit; a DC-DC boot power converion circuit; a DC-AC half bridge inverter circuit; and a reonating circuit to ignite the lamp and maintain Subtantially contant power output of the lamp: wherein the DC-AC half bridge inverter circuit i further compried of a gate iolation tranformer connected in a half bridge inverter chematic which ue a ballat integrated circuit (IC) to drive a high ide MOSFET and a low ide MOSFET: wherein the gate iolation tranformer electrically iolate a gate ignal to the high ide MOSFET; and wherein the gate iolation tranformer i part of a driver circuit compriing: a coupling capacitor placed in erie behind a high output ignal and a firt primary ide of the iolation gate tranformer; and a diode connected acro a gate reitor, wherein an anode of the diode i connected to a firt econdary ide of the iolation gate tranformer and a cathode of the diode i connected to at leat one of the following: a Zener diode connected acro a gate and a ource of the high ide MOSFET, the gate of the high ide MOSFET and a gate-ource reitor connected acro the gate and the ource of the high ide MOSFET; wherein a econd primary ide of the iolation gate tranformer i connected to a digital ground; and wherein a econd econdary ide of the iolation gate tranformer i connected to the ource of the high ide MOSFET. 2. The ballat circuit of claim 1, wherein the ballat circuit i protected with a common mode, differential mode filter and a waveform correction circuit i added in parallel. 3. The ballat circuit of claim 1, wherein a winding ratio of the gate iolation tranformer i 1:1, input and output ignal of the gate iolation tranformer are in phae and the coupling capacitor i connected in erie with primary winding of the gate iolation tranformer. 4. The ballat circuit of claim 1, wherein a pair of Zener diode i connected acro the gate and the ource of the high ide MOSFET to make ure that the gate voltage of the high ide MOSFET doe not exceed a pecified negative Voltage or a pecified poitive Voltage. 5. The ballat circuit of claim 1, wherein the reonating circuit comprie a reonating inductor in erie between a DC blocking capacitor and a reonating capacitor connected in parallel with the induction fluorecent lamp and the value of the reonating capacitor i Smaller than the DC blocking capacitor. 6. The ballat circuit of claim 5, wherein the induction fluorecent lamp ha a running frequency of 1995 khz with a preheat frequency of khz and a reonating fre quency of 2315 khz. 7. The ballat circuit of claim 6, wherein the ballat circuit i protected with a common mode, differential mode filter and a waveform correction circuit i added in parallel. 8. The ballat circuit of claim 5, wherein a Q-curve of the induction fluorecent lamp i hifted uch a way that the difference between a reonance frequency and a running frequency i 30 khz or greater when the ballat circuit i operating at 85 C. 9. A ballat circuit for a lighting ytem uing an induction fluorecent lamp, compriing: an AC-DC rectification circuit; a DC-DC boot power converion circuit; a DC-AC half bridge inverter circuit; and a reonating circuit to ignite the lamp and maintain Subtantially contant power output of the lamp: wherein the DC-AC half bridge inverter circuit i further compried of a gate iolation tranformer connected in

18 11 a half bridge inverter chematic which ue a ballat integrated circuit (IC) to drive a high ide MOSFET and a low ide MOSFET wherein the gate iolation tranformer electrically iolate a gate ignal to the high ide MOSFET: wherein the reonating circuit comprie a reonating induc tor in erie between a DC blocking capacitor and a reo nating capacitor connected in parallel with the induction fluorecent lamp and the value of the reonating capacitor i Smaller than the DC blocking capacitor; and wherein a Q-curve of the induction fluorecent lamp i hifted uch a way that the difference between a reo nance frequency and a running frequency i 30 khz or greater when the ballat circuit i operating at 85 C. k k k k k