Title of Invention

AN ELECTRONIC BALLAST FOR HIGH WATTAGE HIGH INTENSITY DISCHARGE LAMP

Abstract This is self oscillated resonant mode power mosfet based High Intensity Discharge Lamp Electronic Ballast with full bridge inverter from a pulsated DC voltage using DC Link and Power Factor correction circuit Active/Passive, with in-built ignition and short circuit protection circuit, frequency controlled, established capacity of power to drive single/multi higher watt HID lamps up to 5000 watt by in a stable flicker free ionisation of the plasma present in the metal halide, sodium vapor and mercury vapor lamps.
Full Text FIELD OF THE INVENTION
The present invention relates to ballast for high intensity discharge lamps and, in particular, to an electronic ballast for such high intensity discharge lamp. Importantly, the electronic ballast of the invention is adapted to save energy by way of avoiding the energy losses in conventional ballast system which are known consume lot of energy. Moreover, the electronic ballast apart from being energy saving would also be reliable and user friendly in its application as a ballast or high wattage high intensity discharge lamp. The electronic ballast of the invention would favour for effective utilization in relation to HID lamps in particular lights used for outdoor, industrial and play grounds which are usually of high wattage of about 70 watt to 2000 watt per lamp. The electronic ballast achieves the above power saving without compromising illumination level and is found to be reliable for operation at any voltage.
BACKGROUND ART
It is well known to provide ballast for operation or lighting of HID lamps which are usually of higher wattage i.e. about 70 watt to 2000 watt.
It is well known that basically the ballast systems conventionally in use comprise of a core of steel lamination surrounded by copper and aluminum coils, a condenser and igniter. In particular, a core of steel lamination surrounded by copper and aluminum coil is adapted to transform electrical power to pass the current by the passage through core and coil creating electrical resistance. Such provision is adapted as per lamp ignition voltage and power regulation. The condenser we use is basically an AC capacitor and is adapted to improve the power factor, phase displacement and current limiting provision. The igniter means use is basically an electronic circuit to create high pulse using a firing circuit. Normally, such HID ballast requires a very high pulse from 2.5-4.0 KV. to ignite the lamp. Importantly, such igniter is used to provide the pulse to start the lamp initially.
It is found that in such conventional HID Lamp ballast wherein the electrical resistance is created by the passage of current through the core and coil of an
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electro magnetic ballast, the electrical energy is converted into heat energy. Due to such conversion of the electrical energy into heat energy there is power loss, which is known as ballast losses and such power loss can not be thus used for producing the light from the lamp. Moreover, such conventional ballast systems are also subject to further loss created from noise (harmonic) making harmonic distortion. As regards the reliability of such conventional ballast the same suffer from problems of reliability since it involves the use of an electrical igniter which fails repeatedly. Also, due to heat on core and coil the ballast causes breakdown on the copper / aluminum coil insulation. Moreover, at high voltage the ballast gets burnt as the current increases proportionately with rise in voltage. Apart from the aforesaid it is also experienced that such conventional ballast can not start at voltage below 200 volt A.C., which adds to the limitation of use of such ballast. Added to the above, it is also known that since such conventional ballast operate at 50Hz., they produce a stroboscopic effect. The 50Hz. operation leads to blinking which can be seen by the naked eye. In particular, in case of lighting in stadium such blinking effect resulting from the ballast is found to disturb and harm the players / performers due to flickering of the light. Also, it is further known that such conventional ballast are heavy in weight and accordingly more the lamp wattage desired to be operated more is the weight of the ballast, which again add to the complexity of its assembling and use.
It is thus apparent from the above that the conventional / magnetic ballast system suffer from inherent problems of operation as well as are not to the users benefit due to extensive power consumption and related complexities of use and reliability as discussed hereinbefore.
OBJECTS OF THE INVENTION
It is thus basic object of the present invention to provide for electronic ballast high wattage high intensity discharge lamps, which would avoid the limitations and shortcomings of the conventional and presently available ballast use in the art.
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Another object of the present invention is to provide an electronic ballast for high wattage high intensity discharge lamp which would be adapted to save energy as compared to conventional ballast upto 40% without compromising illumination (lux) level due to low loss in electronic component followed by choke.
Another object of the present invention is directed to an electronic ballast for high wattage high intensity discharge lamp, which would be simple and cost effective to manufacture and would also not require complex maintenance requirements.
A further object of the present invention is directed to provide an electronic ballast for high wattage which would be adapted to work at any voltage in the range of 90-270 volt or 180-470 volt.
A further object of the present invention is directed to an electronic ballast for high voltage high intensity discharge lamp adapted for multi lamp operation involving a single ballast.
A further object of the present invention is directed to an electronic ballast high wattage high intensity discharge lamps, which would be free of any stroboscopic effect and can operate at high frequency.
Another object of the invention is directed to an electronic ballast which would not be of heavy weight and can be obtained as light weight ballast involving compact and light weight electronic components only.
SUMMARY OF THE INVENTION
Thus according to the basic aspect of the present invention there is provided an electronic ballast for high wattage high intensity discharge lamp comprising:
a rectifier means for converting the input AC signal into DC;
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a power factor correction means adapted for generating a pulsated DC signal in addition to Power factor improvements;
said pulsated DC signal adapted to be formed in parallel with the function of a full bridge inverter having four Mosfets;
a power transformer means operatively connected to said full bridge inverter means and adapted to generate the required induced voltage such as to effect controlled ignition based on said transformer and isolated drive to said Mosfets and activate the said higher wattage HID lamps.
In the above disclosed electronic ballast for high wattage high density discharge lamp the said power factor correction means comprise selectively a Passive Power Factor Correction (PPFC) or a Active Power Factor Correction (APFC) means. The said Passive Power Factor Correction (PPFC) means is adapted to generate 200-300 DC volts as per AC input signal and said Active Power Factor Correction (APFC) means adapted to generate a DC voltage from 400-450Volts.
The said pulsated DC output using Mosfet comprise drain voltage of Mosfets adapted to build sufficient power to drive high watt HID lamps at controlled frequency.
Importantly, the said full bridge inverter comprises of four mosfets supplied with isolated gate signals .The two of said Mosfets are adapted to operate as one switch while the other two are adapted to operate as another switch and said two sets of switches remain ON/OFF at alternate phase. The pulse gate drive of self-oscillated type is applied to the Mosfets with speed up diode to scale up gate resistance to thereby speed up the Mosfet turn ON while leaving the turn OFF slow.
Advantageously, the arc stability in the lamp is tuned with variable frequency based on said power transformer and its inductance. The primary windings of said transformer and its inductance are tuned depending upon the lamp wattage, frequency and current required to be delivered to the load. The current delivered to the lamp depend upon the lamp voltage and capacitor means selected from single or gang capacitor.
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In accordance with a preferred aspect of the invention, depending upon the lamp firing voltage the internal igniter in said transformer means is tuned using sense voltage from the primary windings involving ignition voltages of upto 4-5 KV. The said sense voltage is passed through diac and controlled by SCR for providing high ignition voltage to the HID lamps for ignition. Thus, depending upon the lamp the igniter is directly tuned from the isolated transformer itself.
In accordance with another preferred aspect of the invention the electronic ballast for high wattage high intensity discharge lamp comprises providing series of condensers from the isolated transformer adapted to operate single or multiple HID-lamps.
Importantly, according to yet further aspect of the invention, the lamp terminal is protected from short circuit through isolation and tends to OFF when short circuit is found and remains OFF till the circuit is in order to operate the lamp properly.
It is possible by way of afore-discussed electronic ballast for high wattage high intensity discharge lamp of the invention to provide for a light weight electronic ballast which is simple to obtain and also reliable to operate and use.
Importantly, it is found that the electronic ballast of the invention has disclosed about can save energy as compared to the conventional ballast of upto about 40% without compromising (Lux) level since the power lost in electronic component is much less as compared to the consumption of power and heat loss in the conventional ballast / chokes.
Advantageously, as further apparent from the disclosure herein, the electronic ballast of the invention does not require any complex or cost extensive operating components and is thus reliable and require reduced maintenance as compared to the conventional ballast. Also, in view of the stability in its performance there is no stroboscopic effect observes in use of the electronic ballast of the invention even at high frequency.
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Advantageously the electronic ballast further avoids the limitation of the conventional ballast being operative only at 210-270 volts and not at low voltage and makes it possible to achieve the ballast function at any voltage such as in the range 90-270 volts or 180-470 volts. Moreover, electronic ballast of the invention makes possible multi lamp operation involving a single ballast. Also, less weight of the electronic component further at to the benefit of the electronic ballast of the invention as compared to the conventionally available to the ballast.
The details of the invention, its object and advantages are explained hereunder in greater detail in relation to non-timiting exemplary illustration of the electronic ballast and its operating circuit as per the following accompanying figures.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURE.
Fig 1-Illustrates a conventional ballast circuit presently available to the art;
Fig.lA - Illustrates schematically by way of a block diagram the electronic ballast system in accordance with the present invention;
Fig. 2 - Illustrates the two types of AC to DC converter with Power Factor Correction circuit which can be used in the electronic ballast of the invention (i) Passive Power Factor Correction and (ii) Active Power Factor Correction.
Fig. 3- Illustrates a typical pulsated DC waveform after resonance using Passive Power Factor Correction circuit.
Fig. 4- Illustrates a typical pulsated DC waveform after resonance using Active Power Factor Correction circuit.
Fig. 5 & 6 - Illustrates a configuration of mosfets Q1-Q4 and their Gate Drive signal generated from the pulse transformer;
Fig 7 - It shows the same as fig 5 & 6, but in this case the source is APFC;
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Fig 8 - Fig. 8 (1 & 2) illustrates the drain voltages with respect to ground after the circuit goes into resonance and fig-8 (3) above shows voltage across one set of mosfets when OFF and other set of mosfets is ON.
Fig. 9 - Illustrates single / parallel DC link using L/C network depending upon the circuit current used after Rectifier and Power Factor correction circuit;
Fig. 10- Illustrates a common ignition circuit used in the feed back loop of transformer adapted to be active when the circuit fails itself to ignite the lamp;
Fig. 11 - Illustrates a basic block diagram for Active Power Factor correction circuit using Ics as per standard specifications;
Fig. 12 - Illustrates the signal delivered to the lamp wherein frequency is controlled by L-C network as desired to drive the lamp smoothly.
Fig. 13 - Illustrates the direction of current flow in DC Link after it goes in to resonance.
DETAIL DESCRIPTION OF THE INVENTION
Reference is first invited to accompanying figure 1 which illustrates a common circuit diagram of a conventional ballast involving a core and coil ballast which use a tapped transformer with external igniter and condenser to improve power factor. As explained earlier, due to conversion of the electrical energy into heat energy there is power loss in such ballasts, which is known as ballast losses and such power loss can not be thus used for producing the light from the lamp. Moreover, such conventional ballast systems are also subject to further loss created from noise (harmonic) making harmonic distortion. There are also problems of reliability since it involves the use of an electrical igniter, which fails repeatedly. Also, such ballasts have breakdown problems and at high voltage the ballast gets burnt as the current increases proportionately with rise in voltage. There are also problems of stroboscopic effect. Also, it is further known that such conventional ballast are heavy in weight and accordingly more the lamp
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wattage desired to be operated more is the weight of the ballast, which again add to the complexity of its assembling and use.
Reference is now invited to accompanying Figure 1A which schematically illustrates by way of a blocks the various operating units in the electronic ballast of the present invention. As clearly shown in the figure the electronic ballast basically of the rectifier means (1R) for converting the input AC signal into DC, a power factor correction means (1) adapted for generating a pulsated DC signal apart from its Power Factor improvement wherein the said pulsated DC signal is adapted to be formed in parallel with the function of a full bridge inverter (4) having four Mosfets (Q1,Q2,Q3 and Q4).The invertor output is operatively connected to the power transformer means (10) adapted to generate the required induced voltage such as to effect controlled ignition based on said transformer and isolated drive to said Mosfets and activate the said higher wattage HID lamps.
As also shown in the figure 1A ,in the electronic ballast for high wattage high intensity discharge lamp the said power factor correction means (1) can comprise selectively a Passive Power Factor Correction (PPFC) or a Active Power Factor Correction (APFC) means. Such Power Factor Correction means are further shown in accompanying Figure 2. In particular the power factor correction means can be two types of power factor correction involving (i) Passive Power Factor Correction Circuit wherein the desired DC output is low and an active power factor correction wherein the DC output is high as compared to the passive power factor correction circuitry. Thus the said Passive Power Factor Correction (PPFC) means is adapted to generate 200-300 volts as per AC input signal and said Active Power Factor Correction (APFC) means adapted to generate a DC voltage from 400-450Volts.More particularly, the typical pulsated DC waveform after resonance using Passive power factor correction circuit and the pulsated DC waveform after resonance using Active power factor correction circuit are illustrated in greater detail in accompanying figures 3 and 4 respectively.
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Reference is invited to accompanying figures 5 and 6 which illustrates in further detail the inverter (4) and, in particular, the configuration of the mosfets Q1-Q4 and their gate drive signals generated form the pulse transformer. As would be further clearly apparent from figures 5 and 6, in the case of PPFC mode when Ql and Q3 are made ON with applied gate drive signal, Q2 and Q4 are made OFF without gate drive and vice versa.
Likewise in the case of APFC mode the corresponding gate drive illustration is provided in accompanying figure 7. In this case, however, due to high voltage there is preferably a zener cut-OFF protection provided at the gate of the mosfet.
The said pulsated DC output using Mosfet comprise drain voltage of Mosfets adapted to build sufficient power to drive high watt HID lamps at controlled frequency (Refer figures 8 (1,2 & 3)).In particular, figures 8 (1&2) illustrates the drain voltages with respect to ground after circuit goes into resonance while figure 8(3) shows the voltage across one set of mosfets when OFF and the other set of mosfets are ON.
Importantly, thus the above said full bridge inverter comprises of four mosfets supplied with isolated gate signals. The two of said Mosfets are adapted to operate as one switch while the other two are adapted to operate as another switch and said two sets of switches remain ON/OFF at alternate phase. The pulse gate drive of self-oscillated type is applied to the Mosfets with speed up diode to scale up gate resistance to thereby speed up the Mosfet turn ON while leaving the turn OFF slow.
Figure 9 illustrates a basic standard single/parallel DC link using L/C network (2) depending upon the circuit current used after rectifier (1R) and power factor correction circuit (2).
Advantageously, the arc stability in the lamp is tuned with variable frequency based on said power transformer and its inductance. The primary windings of said transformer and its inductance are tuned depending upon the lamp wattage, frequency and current required to be delivered to the load. The current delivered
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to the lamp depend upon the lamp voltage and capacitor means selected from single or gang capacitor as also shown in figure 1.
In accordance with a preferred aspect of the invention, depending upon the lamp firing voltage the internal igniter in said transformer means it is tuned using sense voltage from the primary windings involving ignition voltages of upto 4-5 KV. The said sense voltage is passed through diac and controlled by SCR for providing high ignition voltage to the HID lamps for high ignition. Thus, depending upon the lamp the igniter is directly tuned from the isolated transformer itself.
Reference is invited to accompanying figure 10, which illustrates a common ignition circuit used in the feed back loop of transformer, which is adapted to be active when the circuit fails itself to ignite the lamp. In particular, the firing circuit (13) in figure 1 , in case of ignition by APFC circuits , the voltage is sensed from the primary windings of transformer and given to the firing circuit. Figure 11 illustrates a basic standard block diagram for Active Power factor correction circuit using known infenion Ics as per standard specifications. Figure 12 illustrates the provision of the delivery of the signal to the lamp wherein the frequency is controlled by L-C network required to drive the lamp smoothly. Figure 13 illustrates a basic resonance circuit using L/C network and in particular the direction of the current flow in DC link after it goes into resonance.
In accordance with another preferred aspect of the invention the electronic ballast for high wattage high intensity discharge lamp can comprise providing series of condensers from the isolated transformer adapted to operate single or multiple HID-lamps.
Also according to an aspect of the invention, the electronic ballast of the invention is preferably also provided with hot re-strike protection system. In particular as shown in figure 1, the hot re-strike protection system is indicated by reference (12). Thus after some hours of operation the HID lamp gets hot and if it turns OFF and again makes it ON , it does not ignite immediately due to its characteristics. Hence the entire ignition voltage (high) remains across the
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lamp. Thus the ignition is made at certain intervals to protect the lamp from high voltage or ignition voltage till it gets ON.
Importantly, according to yet further aspect of the invention, the lamp terminal is protected from short circuit through isolation and tends to OFF when short circuit is foutid and remains OFF till the circuit is in order to operate the lamp properly. In particular as shown in figure 1A, the short circuit protection means (14) provided in the ballast system of the invention. Thus if the lamp is found short or if the binary output (all HID lamps have two ends to connect to circuit) is shorted, then the sense voltage becomes zero, stops firing also stops control circuit (2) shut down, till the lamp end is shorted. Again automatically it gets ON if opened or connected with good condition lamp.
Also the electronic ballast of the invention is provided with over current protection means (15) and in case the current exceeds due to bad electrical signal or earth missing, then the extra current is sensed from Transformer (10) to the APFC circuit (1) making active shut down. Likewise there is also provision for over voltage protection (16) as shown in figure l.Such over voltage may occur during initial start up or output sparking etc. The over voltage regulator reduces the multiplier output voltage in case of APFC circuit.
Thus basically the high intensity lamps are from 35 watt to higher wattage i.e. 2500 watt and the ruggedness to withstand power is needed to drive such higher wattage lamp in case of its function through low loss inverter. As already discussed in relation to Figure 1A from the ac line voltage normally from (90-400volts), the DC signal is produced using full wave rectifier (1R). The DC signal is passed through the power factor correction circuit (1) using a passive or Active power factor correction circuit (fig-lA) for an improved power factor. The different DC voltage is produced from the different boost up power factor correction circuit. The active power factor correction circuit produces a DC voltage from 400-450 volts whereas passive circuits generate 200-300 volts as per ac input signal. After the DC signal is modulated to a pulsated DC signal (3) (as per fig-3 by using PPFC and fig-4 using APFC), . Normally this modulation is formed in parallel with the function of full bridge inverter (4). The peak or, amplitude of the pulsated signal is calculated from the DC voltage by boost up
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circuit. This helps in deciding Vds for the power mosfets to be used in the inverter. Full bridge inverter uses the four mosfets Ql, Q2, Q3 & Q4. These mosfets are supplied with isolated gate signal (5,6,7, & 8) (fig-6 in case of PPFC & Fig-7 in case of APFC) generated from the power transformer (10). The peak drive is applied as required by the mosfet's gate drive limitation. A Zener is used for a cut-off in excess drive signal for safety (fig-7). The isolated drive signal is limited through a current limiting resistance and speed up diode as scaled upward to make faster turn-ON while leaving turn-OFF slow. The operation starts with after supplied Vds and Vgs, when Ql and Q3 works as one switch and Q2 and Q4 plays as another (signal wave form at fig-lA). The two set of switches remain ON/OFF at alternate phase.
The arc stability in the lamp is tuned with variable frequency designed from power transformer with its inductance. The primary winding and its inductance are tuned depending upon the lamp wattage, frequency and current required to be delivered to the load. The current delivered to the lamp depends upon the lamp voltage and single as well as gang capacitor is used in isolated load as also illustrated in Figure 1A.
Depending upon the lamp firing voltage the internal igniter is tuned with help of sense voltage from primary winding. In some types of the lamp the use of igniter may be directly tuned from the isolated transformer itself. In case of the igniter the sense voltage is passed through diac and controlled by SCR for providing high ignition voltage to the HID lamps for high ignition. After ignition the firing pulses tends to zero.
As also explained above, the lamp terminal is protected from short circuit through isolation and tends to OFF when short circuits is found and remain OFF till the circuit is in order to operate the lamp properly.
It is thus possible by way of the above invention to provide for electronic ballast high wattage high intensity discharge lamps, which would avoid the limitations and shortcomings of the conventional and presently available ballast use in the art. In particular, electronic ballast for high wattage high density discharge lamp would be adapted to save energy as compared to conventional ballast upto 40%
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without compromising illumination (lux) level due to low loss in electronic component followed by choke. Importantly, the electronic ballast is lightweight, user friendly and would be simple and cost effective to manufacture and would also not require complex maintenance requirements. Advantageously as further discussed hereinbefore, the electronic ballast for high voltage high density discharge lamp adapted for multi lamp operation involving a single ballast and also is free of any stroboscopic effect and can operate at high frequency.
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WE CLAIM:
1. An electronic ballast for high wattage high intensity discharge lamp comprising:
a rectifier means for converting the input AC signal into DC;
a power factor correction means adapted for generating a pulsated DC signal with Power factor improvement;
sard pulsated DC signal adapted to be formed in parallel with the function of a full bridge inverter having four Mosfets;
a power transformer means operatively connected to said full bridge inverter means and adapted to generate the required induced voltage such as to effect controlled ignition based on said transformer and isolated drive to said Mosfets and activate the said higher wattage HID lamps.
2. An electronic ballast for high wattage high intensity discharge lamp as
claimed in claim 1 wherein said power factor correction means comprise
selectively a Passive Power Factor Correction (PPFC) or a Active Power
Factor Correction (APFC) means.
3. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 or 2 wherein said pulsated DC output using
Mosfet comprise drain voltage of Mosfets adapted to build sufficient power
to drive high watt HID lamps at controlled frequency.
4. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 3 wherein said Passive Power Factor
Correction (PPFC) means is adapted to generate 200-300 volts as per AC
input signal and said Active Power Factor Correction (APFC) means
adapted to generate a Dc voltage from 400-450Volts.
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5. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 4 wherein said full bridge inverter
comprises of four mosfets (Ql, Q2, Q3 and Q4) supplied with isolated
gate signals (5,6,7 and 8).
6. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 5 wherein said Ql and Q3 are adapted to
operate as one switch while Q2 and Q4 are adapted to operate as another
switch and said two sets of switches remain ON/OFF at alternate phase.
7. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 6 wherein pulse gate drive of self-
oscillated type is applied to the Mosfets with speed up diode to scale up
gate resistance to thereby speed up the Mosfet turn ON while leaving the
turn OFF slow.
8. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 7 wherein the arc stability in the lamp is
tuned with variable frequency based on said power transformer and its
inductance.
9. An electronic ballast for high wattage high intensity discharge lamp as
claimed in claim 8 wherein the primary windings of said transformer and
its inductance are tuned depending upon the lamp wattage, frequency and
current required to be delivered to the load.
10. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 9 wherein the current delivered to the
lamp depend upon the lamp voltage and capacitor means selected from
single or gang capacitor.
11. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 8 to 10 wherein depending upon the lamp
firing voltage the internal igniter in said transformer means is tuned using
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sense voltage from the primary windings involving ignition voltages of upto 4-5 KV.
12. An electronic ballast for high wattage high intensity discharge lamp as
claimed in claim 11 wherein the said sense voltage is passed through diac
and controlled by SCR for providing high ignition voltage to the HID lamps
for high ignition.
13. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 12 wherein depending upon the lamp the
igniter is directly tuned from the isolated transformer itself.
14. An electronic ballast for high wattage high intensity discharge lamp as
claimed in claim 13 comprising providing series of condensers from the
isolated transformer adapted to operate single or multiple HID-lamps.
15. An electronic ballast for high wattage high intensity discharge lamp as
claimed in anyone of claims 1 to 14 wherein the lamp terminal is
protected from short circuit through isolation and tends to OFF when short
circuit is found and remains OFF till the circuit is in order to operate the
lamp properly.
16. An electronic ballast for high intensity discharge lamp as claimed in
anyone of claims 1 to 15 wherein in additional loads single or, parallel
transformer is involved to multiply additional HID lamp wattage
operational capacity.
17. An electronic ballast for high wattage high intensity discharge lamp
substantially as herein described and illustrated with reference to the
accompanying figures.

Date: 16/12/2003
(APPLICANT)
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This is self oscillated resonant mode power mosfet based High Intensity Discharge Lamp Electronic Ballast with full bridge inverter from a pulsated DC voltage using DC Link and Power Factor correction circuit Active/Passive, with in-built ignition and short circuit protection circuit,
frequency controlled, established capacity of power to drive single/multi
higher watt HID lamps up to 5000 watt by in a stable flicker free ionisation of
the plasma present in the metal halide, sodium vapor and mercury vapor lamps.

Documents:

00635-kol-2003-abstract.pdf

00635-kol-2003-claims.pdf

00635-kol-2003-description(complete).pdf

00635-kol-2003-drawings.pdf

00635-kol-2003-form-1.pdf

00635-kol-2003-form-18.pdf

00635-kol-2003-form-2.pdf

00635-kol-2003-form-3.pdf

00635-kol-2003-form-5.pdf

00635-kol-2003-letters patent.pdf

635-KOL-2003-FORM 15.pdf


Patent Number 206424
Indian Patent Application Number 635/KOL/2003
PG Journal Number 17/2007
Publication Date 27-Apr-2007
Grant Date 27-Apr-2007
Date of Filing 16-Dec-2003
Name of Patentee SUBODHA CHANDRA RATH
Applicant Address M/s. OMTEK ELECTRONICS (P)LIMITED, 257/6 SASTRINAGARA UNIT-4, BHUBANESWAR 751004
Inventors:
# Inventor's Name Inventor's Address
1 SUBODHA CHANDRA RATH M/s OMTEK ELECTRONICS (P)LIMITED, 257/6 SASTRINAGARA UNIT-4, BHUBANESWAR 751004
PCT International Classification Number H 05 B 41/295
PCT International Application Number N/A
PCT International Filing date
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 NA