CA2103627A1 - Variable frequency electronic ballast of high power factor and stabilized output voltage - Google Patents
Variable frequency electronic ballast of high power factor and stabilized output voltageInfo
- Publication number
- CA2103627A1 CA2103627A1 CA002103627A CA2103627A CA2103627A1 CA 2103627 A1 CA2103627 A1 CA 2103627A1 CA 002103627 A CA002103627 A CA 002103627A CA 2103627 A CA2103627 A CA 2103627A CA 2103627 A1 CA2103627 A1 CA 2103627A1
- Authority
- CA
- Canada
- Prior art keywords
- voltage
- pulsating
- power
- frequency
- circuit
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B41/00—Circuit arrangements or apparatus for igniting or operating discharge lamps
- H05B41/14—Circuit arrangements
- H05B41/26—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc
- H05B41/28—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters
- H05B41/282—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices
- H05B41/2825—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage
- H05B41/2828—Circuit arrangements in which the lamp is fed by power derived from dc by means of a converter, e.g. by high-voltage dc using static converters with semiconductor devices by means of a bridge converter in the final stage using control circuits for the switching elements
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
- H02P6/00—Arrangements for controlling synchronous motors or other dynamo-electric motors using electronic commutation dependent on the rotor position; Electronic commutators therefor
- H02P6/14—Electronic commutators
- H02P6/16—Circuit arrangements for detecting position
- H02P6/18—Circuit arrangements for detecting position without separate position detecting elements
- H02P6/185—Circuit arrangements for detecting position without separate position detecting elements using inductance sensing, e.g. pulse excitation
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention relates to a variable frequency electronic ballast of high power-factor and stabilized output-voltage which is used for fluorescent lamps and other gas discharge lamps. A rectifying circuit changes input AC power voltage to full-wave rectified pulsating DC voltage. A
voltage-controlled oscillator is used to produce a high-frequency signal and the variation of the frequency is based on the pulsating DC voltage. The high-frequency signal is amplified in the driving circuit to drive an electronic switch.
The electronic switch inverts the pulsating DC voltage into a variable high-frequency square-wave voltage, but this voltage still pulsates with the pulsating DC voltage. Then the variable high-frequency square-wave voltage passes through a resonant circuit to become a constant-amplitude wave voltage and supplies a constant power to lamp. Because the system can operate in the condition of variable voltage, the rectifying circuit does not need a big volume filter capacitor, the distortion of input current waveform is decreased, and the power-factor is increased. Moreover, the power at the lamp is a constant value when input voltage changes, therefore the system has an equivalent stabilized output-voltage.
The present invention relates to a variable frequency electronic ballast of high power-factor and stabilized output-voltage which is used for fluorescent lamps and other gas discharge lamps. A rectifying circuit changes input AC power voltage to full-wave rectified pulsating DC voltage. A
voltage-controlled oscillator is used to produce a high-frequency signal and the variation of the frequency is based on the pulsating DC voltage. The high-frequency signal is amplified in the driving circuit to drive an electronic switch.
The electronic switch inverts the pulsating DC voltage into a variable high-frequency square-wave voltage, but this voltage still pulsates with the pulsating DC voltage. Then the variable high-frequency square-wave voltage passes through a resonant circuit to become a constant-amplitude wave voltage and supplies a constant power to lamp. Because the system can operate in the condition of variable voltage, the rectifying circuit does not need a big volume filter capacitor, the distortion of input current waveform is decreased, and the power-factor is increased. Moreover, the power at the lamp is a constant value when input voltage changes, therefore the system has an equivalent stabilized output-voltage.
Description
21036~7 .. . . ..
.
VARIABL~ FR~QU~NCY ~L~CTRONIC BALLAST OF
NIGH POWER ~ACTOR AND STABILIZ~D OUTPUT VOLTAG~
: ' The present invention relates to an electronic ballast ~- -system, and more particulary to a variable frequency electronic -ballast system of high power-factor and stabilized output-voltage, which is used for fluorescent lamps and other gas discharge lamps. -Electronic ballast systems for fluorescent lamps and other gas discharge lamps are known in the art. However, in most of prior art electronic ballast systems, the principle of operation is: First, the input AC power is changed to a constant DC voltage power by a rectifier and a filter, then a DC/AC inverter is used to change the DC voltage power to high frequency voltage power to light the lamp. Because the inverter only works in the waveless DC power, the system must use a big filter capacitor to filter off the pulsating wave after rectifying. Therefore, the system has input current only when the input voltage exceeds the voltage of the filter - ;
capacitor. The result is that the input current waveform is distorted, which causes low power-factor and high quantity of harmonics for the input AC power.
The present invention provides a substantially variable freguency electronic ballast system having an AC power source for actuating at least one gas discharge lamp. The ballast system comprising: A rectifying circuit is connected to the AC
power source for supplying a full-wave rectified pulsating DC
voltage. A voltage-controlled oscillator is connected to the pulsating DC voltage ~or establishing a substantially high frequency oscillating signal, the frequency of this signal varies with the pulsating DC voltage. A driving circuit is connected to the oscillator for amplifying the high freguency oscillating signal. An electronic switch is connected to the driving circuit, the pulsating DC voltage is coupled to the electronic switch as a power supply, for providing an inverted ~ :
high frequency square-wave voltage power. A resonant circuit -is linked between the electronic switch and the lamp for establishing a stabilized output-voltage.
Said rectifying circuit includes a full-wave rectifier.
_ . . ~ . , - ,.
. .
-- 2la3627 `~
The rectifying circuit may also have a small capacitor for preventing the output voltage being reduced to zero, but the capacitor must be so small that the output of the rectifying circuit still maintains more than fifty percent original pulsation.
Said voltage-controlled oscillator includes a linear voltage-controlled oscillator, the function of which is that the output frequency varies with the input voltage. The voltage-controlled oscillator may also have a nonlinear corrector for correcting output nonlinear difference of the ballast system, which is caused by said resonant circuit. The nonlinear corrector has at least one nonlinear device; for ~-example: Zener diode etc.
Said driving circuit has at least one amplifier, the function of which is to amplify the oscillating sigDal.
Said electronic switch has at least one semiconductor device, for example: Transistor, SCR, MOSFET, IC etc., the function of which is to invert the pulsating DC voltage to high frequency voltage.
Said resonant circuit consists of at least one inductor and at least one capacitor, the function of which is when the operating frequency changes, the rate of input/output voltage also changes in the resonant circuit. In the present invention, some electronic ballast systems may be applled for two or more lamps. In this case, the resonant circuit has the same number of groups of output terminals, for actuating the lamps.
Various other advantages of the present invention will be readily apparent from the following detailed description when considered in connection with the accompanying drawing forming a part thereof and in which:
Figure 1 is a block diagram shown in said variable frequency electronic ballast system embodying the present invention;
Figure 2 is a practical schematic circuit of the present invention;
Figure 3 is a practical schematic circuit of the V.C.O.
and Driving module.
Referring to the Figure 1, there is shown the block 4~ diagram of a variable frequency electronic ballast system. In Figure 1, an AC power source 10 is applied to a rectifying ~ 21~3627 _ . .:
circuit 20, the output of rectifying circuit 20 is a full-wave rectified pulsating DC voltage and supplied to the DC lines 21 and 22. A voltage-controlled oscillator 30 is connected to the DC lines 21 and 22 at its input terminals 31 and 32. A driving circuit 40 is connected between the oscillator 30 and an electronic switch S0, for amplifying the high frequency signal from the oscillator 30 to trigger the electronic switch 50.
The DC lines 21 and 22 are also connected to the electronic - ~:
switch 50 as a power supply; the electronic switch S0 inverts ~ -- -the pulsating DC voltage to the high frequency voltage but the high frequency voltage still includes the pulsating component.
A resonant circuit 60 is applied to smooth pulsation of the high frequency voltage, which is linked between the electronic switch 50 and the lamp 70.
The practicable circuits of the present invention may be --designed in various ways. Figure 2 just shows one of them.
In Figure 2, an AC power source 10 of sinusoidal voltage is applied to a rectifying circuit 20, the unidirectional pulsating voltage output of which is supplied directly between the DC lines 21 and 22, with the positive voltage being ~ -connected to the line 21. The rectifying circuit 20 consists of a full-wave bridge rectifier 23 and a small capacitor 24.
The volume of small capacitor 24 is about 1/5 to 1/10 of a ~ -regular filter capacitor. In this system, a voltage-controlled oscillator with a nonlinear corrector and a driving circuit are made up of a V.C.O. and Driver module 90. For more description, a schematic circuit of the module 90 is shown in Figure 3. The electronic switch 50 includes two serial transistors 51 and 52, four driving output terminals 41, 42, 43 and 44 from module 90 which are connected to the bases and the emitters of transistors 51 and 52 respectively; the serial connection point of transistors 51 and 52 is as an output terminal of electronic switch 50; the collector of transistor Sl and emitter of transistor 52 are connected to the DC lines 21 and 22 respectively. The resonant circuit 60 has two groups of output terminals and connected to two lamps 71 and 72. In the resonant circuit 60, the inductors 61, 64 and the capacitors 62, 63, 65, 66 compose two similar resonant networks respectively.
Figure 3 shows the detail of V.CØ and Driver module 90.
In the Figure 3, the module 90 has a voltage-controlled 3 ~ ~ ~
::
::
:: :
` 2103627 "' ' oscillator 30 with a nonlinear corrector, a driving circuit 40 and a simple supplying circuit. The supplying circuit includes a diode 91, two voltage reducing resistors 92, 93 and two filter capacitors 94, 95. The voltage-controlled oscillator with a nonlinear corrector 30 is composed of two parts: One is a nonlinear corrector part, which includes four resistors 33, 34, 35, 36, a zener diode 37 and a transistor 38~ Another part is a linear voltage-controlled oscillator 39, which may consist of an IC (for example LM3900, CD4007) and surrounding elements.
(Reference- C. Sondgeroth, More PLL Magic, 73 Magazine, Aug.
1976, p 56-59; \ W.J. Prudhomme, CMOS Oscillators, 73 Magazine, July 1977, p 60-63). The driving circuit includes a driving transistor 45 and a driving transformer 46.
The operation of the circuit of Figure 2 and Figure 3 may be explained as follows:
In Figure 2, the AC power source 10 represents an ordinary electric utility power line, the nominal value of which is 120V/60Hz, the voltage from which is applied directly to the bridge rectifier identified as 23. This bridge rectifier is of conventional construction and provides for the full-wave rectified voltage to be applied to the V.C.O. and Driver module 90 and the electronic switch 50 by way of the DC lines 21 and 22. The small volume capacitor 24 is connected directly across the output of the bridge rectifier 23, in which a little energy is stored so that when the output voltage of the bridge rectifier is going to be zero, the energY is discharged from the capacitor 24 keeping the DC voltage above zero. But the capacitor 24 is so small that the DC voltage is still pulsating, and the valley and peak values are about 40V - 160V.
The V.C.O. and Driving module 90 is connected as Figure 2 and inside operation of which is as Figure 3.
In Figure 3, the pulsating DC voltage is entered from input terminals 31 and 32. A part of the current becomes DC
supply by way of the diode 91 and the resistors 92 and 93. In this DC supply circuit, the function of diode 91 is to prevent the current returning to terminal 31. The resistors 92 and 93 are used to reduce the DC voltage, and the capacitors 94 and 95 are used for filtering pulsation of the DC voltage. The voltage at the capacitor 94 is applied to the oscillator 30 and 4Q the value is about 18V; the voltage at the capacitor 95 is applied to the driving circuit 40 and the value is about 80V, . . ~
but the values of voltage may be different than the aforesaid, although that depends on what devices are to be used. Besides this use, the pulsating DC voltage is divided by the resistors 33 and 34, then offered to the base of the transistor 38. The transistor 38 and the resistor 35 compose an inverting amplifier and a controlled voltage signal is from the collector of transistor 38. The resistor 36 parallel with the zener diode 37 compose a nonlinear circuit, through which the controlled voltage signal passes into the linear voltage-controlled oscillator 39. The output of linear voltage-controlled oscillator 39 is a high frequency signal, the frequency of which varies with the controlled voltage signal and its value is about 20 KHz to 40 KHz. The high frequency signal is provided to the base of the driving transistor 45 and is amplified. The amplified high frequency signal is from the collector of transistor 45, which circulates through the primary winding of the driving transformer 46. The output of the driving transformer is two high frequency square-wave signals from secondary windings of driving transformer 41 and 48, which are of the same value and opposite phase. The output terminals of the driving signal are identified as 41, 42, 43 and 44 on the module 90.
Bac~ to Figure 2, two serial transistors 51 and 52 compose an electronic switch 50. The terminals 41, 42, 43 and 44 are directly connected to emitters and bases of transistors 51 and 52, and the transistors 51 and 52 switch with the driving signals by turn. A high frequency square-wave voltage power of which frequency and voltage both vary with pulsation of pulsating DC voltage, with output from the emitter of transistor 51 going into the resonant circuit. The resonant circuit has two of the same resonant networks. Each resonant network has an inductor 61 (or 64) in series with a capacitor 62 (or 65), another capacitor 63 (or 66) in parallel with the lamp 71 (or 72) and the lamp 71 (or 72) is in series with the resonant network by way of its filaments. The resonant frequency of the network is designed near and higher than the maximal operating frequency of the electronic switch, and the frequency - output/input characteristic is the higher the operating frequency the greater the voltage rate of output/input. Therefore, when DC voltage between the DC lines 21 and 22 is on the increase, the oscillating frequency of the .
-; ,~
- ,. .
21~3~27 : :
module 90 is decreased. At output of electronic switch 50, the result is that the voltage is increased simultaneously with the decrease in frequency. 8ecause in the resonant circuit, the voltage rate of output/input is decreased with reduction of the operating frequency, when the voltage from electronic switch 50 is increased, which frequency is decreased and the output voltage is decreased to compare with the input voltage. In other words, the output voltage of the resonant circuit is stabilized. The voltage rate of output/input varies with the operating frequency that is usually not linear, and for gaining better compensation, the nonlinear corrector is used. If the frequency - output/input characteristic of resonant circuit is linear enough, the nonlinear corrector would not be used. The voltage-controlled oscillator 30 is the linear voltage-controlled oscillator 39.
.
VARIABL~ FR~QU~NCY ~L~CTRONIC BALLAST OF
NIGH POWER ~ACTOR AND STABILIZ~D OUTPUT VOLTAG~
: ' The present invention relates to an electronic ballast ~- -system, and more particulary to a variable frequency electronic -ballast system of high power-factor and stabilized output-voltage, which is used for fluorescent lamps and other gas discharge lamps. -Electronic ballast systems for fluorescent lamps and other gas discharge lamps are known in the art. However, in most of prior art electronic ballast systems, the principle of operation is: First, the input AC power is changed to a constant DC voltage power by a rectifier and a filter, then a DC/AC inverter is used to change the DC voltage power to high frequency voltage power to light the lamp. Because the inverter only works in the waveless DC power, the system must use a big filter capacitor to filter off the pulsating wave after rectifying. Therefore, the system has input current only when the input voltage exceeds the voltage of the filter - ;
capacitor. The result is that the input current waveform is distorted, which causes low power-factor and high quantity of harmonics for the input AC power.
The present invention provides a substantially variable freguency electronic ballast system having an AC power source for actuating at least one gas discharge lamp. The ballast system comprising: A rectifying circuit is connected to the AC
power source for supplying a full-wave rectified pulsating DC
voltage. A voltage-controlled oscillator is connected to the pulsating DC voltage ~or establishing a substantially high frequency oscillating signal, the frequency of this signal varies with the pulsating DC voltage. A driving circuit is connected to the oscillator for amplifying the high freguency oscillating signal. An electronic switch is connected to the driving circuit, the pulsating DC voltage is coupled to the electronic switch as a power supply, for providing an inverted ~ :
high frequency square-wave voltage power. A resonant circuit -is linked between the electronic switch and the lamp for establishing a stabilized output-voltage.
Said rectifying circuit includes a full-wave rectifier.
_ . . ~ . , - ,.
. .
-- 2la3627 `~
The rectifying circuit may also have a small capacitor for preventing the output voltage being reduced to zero, but the capacitor must be so small that the output of the rectifying circuit still maintains more than fifty percent original pulsation.
Said voltage-controlled oscillator includes a linear voltage-controlled oscillator, the function of which is that the output frequency varies with the input voltage. The voltage-controlled oscillator may also have a nonlinear corrector for correcting output nonlinear difference of the ballast system, which is caused by said resonant circuit. The nonlinear corrector has at least one nonlinear device; for ~-example: Zener diode etc.
Said driving circuit has at least one amplifier, the function of which is to amplify the oscillating sigDal.
Said electronic switch has at least one semiconductor device, for example: Transistor, SCR, MOSFET, IC etc., the function of which is to invert the pulsating DC voltage to high frequency voltage.
Said resonant circuit consists of at least one inductor and at least one capacitor, the function of which is when the operating frequency changes, the rate of input/output voltage also changes in the resonant circuit. In the present invention, some electronic ballast systems may be applled for two or more lamps. In this case, the resonant circuit has the same number of groups of output terminals, for actuating the lamps.
Various other advantages of the present invention will be readily apparent from the following detailed description when considered in connection with the accompanying drawing forming a part thereof and in which:
Figure 1 is a block diagram shown in said variable frequency electronic ballast system embodying the present invention;
Figure 2 is a practical schematic circuit of the present invention;
Figure 3 is a practical schematic circuit of the V.C.O.
and Driving module.
Referring to the Figure 1, there is shown the block 4~ diagram of a variable frequency electronic ballast system. In Figure 1, an AC power source 10 is applied to a rectifying ~ 21~3627 _ . .:
circuit 20, the output of rectifying circuit 20 is a full-wave rectified pulsating DC voltage and supplied to the DC lines 21 and 22. A voltage-controlled oscillator 30 is connected to the DC lines 21 and 22 at its input terminals 31 and 32. A driving circuit 40 is connected between the oscillator 30 and an electronic switch S0, for amplifying the high frequency signal from the oscillator 30 to trigger the electronic switch 50.
The DC lines 21 and 22 are also connected to the electronic - ~:
switch 50 as a power supply; the electronic switch S0 inverts ~ -- -the pulsating DC voltage to the high frequency voltage but the high frequency voltage still includes the pulsating component.
A resonant circuit 60 is applied to smooth pulsation of the high frequency voltage, which is linked between the electronic switch 50 and the lamp 70.
The practicable circuits of the present invention may be --designed in various ways. Figure 2 just shows one of them.
In Figure 2, an AC power source 10 of sinusoidal voltage is applied to a rectifying circuit 20, the unidirectional pulsating voltage output of which is supplied directly between the DC lines 21 and 22, with the positive voltage being ~ -connected to the line 21. The rectifying circuit 20 consists of a full-wave bridge rectifier 23 and a small capacitor 24.
The volume of small capacitor 24 is about 1/5 to 1/10 of a ~ -regular filter capacitor. In this system, a voltage-controlled oscillator with a nonlinear corrector and a driving circuit are made up of a V.C.O. and Driver module 90. For more description, a schematic circuit of the module 90 is shown in Figure 3. The electronic switch 50 includes two serial transistors 51 and 52, four driving output terminals 41, 42, 43 and 44 from module 90 which are connected to the bases and the emitters of transistors 51 and 52 respectively; the serial connection point of transistors 51 and 52 is as an output terminal of electronic switch 50; the collector of transistor Sl and emitter of transistor 52 are connected to the DC lines 21 and 22 respectively. The resonant circuit 60 has two groups of output terminals and connected to two lamps 71 and 72. In the resonant circuit 60, the inductors 61, 64 and the capacitors 62, 63, 65, 66 compose two similar resonant networks respectively.
Figure 3 shows the detail of V.CØ and Driver module 90.
In the Figure 3, the module 90 has a voltage-controlled 3 ~ ~ ~
::
::
:: :
` 2103627 "' ' oscillator 30 with a nonlinear corrector, a driving circuit 40 and a simple supplying circuit. The supplying circuit includes a diode 91, two voltage reducing resistors 92, 93 and two filter capacitors 94, 95. The voltage-controlled oscillator with a nonlinear corrector 30 is composed of two parts: One is a nonlinear corrector part, which includes four resistors 33, 34, 35, 36, a zener diode 37 and a transistor 38~ Another part is a linear voltage-controlled oscillator 39, which may consist of an IC (for example LM3900, CD4007) and surrounding elements.
(Reference- C. Sondgeroth, More PLL Magic, 73 Magazine, Aug.
1976, p 56-59; \ W.J. Prudhomme, CMOS Oscillators, 73 Magazine, July 1977, p 60-63). The driving circuit includes a driving transistor 45 and a driving transformer 46.
The operation of the circuit of Figure 2 and Figure 3 may be explained as follows:
In Figure 2, the AC power source 10 represents an ordinary electric utility power line, the nominal value of which is 120V/60Hz, the voltage from which is applied directly to the bridge rectifier identified as 23. This bridge rectifier is of conventional construction and provides for the full-wave rectified voltage to be applied to the V.C.O. and Driver module 90 and the electronic switch 50 by way of the DC lines 21 and 22. The small volume capacitor 24 is connected directly across the output of the bridge rectifier 23, in which a little energy is stored so that when the output voltage of the bridge rectifier is going to be zero, the energY is discharged from the capacitor 24 keeping the DC voltage above zero. But the capacitor 24 is so small that the DC voltage is still pulsating, and the valley and peak values are about 40V - 160V.
The V.C.O. and Driving module 90 is connected as Figure 2 and inside operation of which is as Figure 3.
In Figure 3, the pulsating DC voltage is entered from input terminals 31 and 32. A part of the current becomes DC
supply by way of the diode 91 and the resistors 92 and 93. In this DC supply circuit, the function of diode 91 is to prevent the current returning to terminal 31. The resistors 92 and 93 are used to reduce the DC voltage, and the capacitors 94 and 95 are used for filtering pulsation of the DC voltage. The voltage at the capacitor 94 is applied to the oscillator 30 and 4Q the value is about 18V; the voltage at the capacitor 95 is applied to the driving circuit 40 and the value is about 80V, . . ~
but the values of voltage may be different than the aforesaid, although that depends on what devices are to be used. Besides this use, the pulsating DC voltage is divided by the resistors 33 and 34, then offered to the base of the transistor 38. The transistor 38 and the resistor 35 compose an inverting amplifier and a controlled voltage signal is from the collector of transistor 38. The resistor 36 parallel with the zener diode 37 compose a nonlinear circuit, through which the controlled voltage signal passes into the linear voltage-controlled oscillator 39. The output of linear voltage-controlled oscillator 39 is a high frequency signal, the frequency of which varies with the controlled voltage signal and its value is about 20 KHz to 40 KHz. The high frequency signal is provided to the base of the driving transistor 45 and is amplified. The amplified high frequency signal is from the collector of transistor 45, which circulates through the primary winding of the driving transformer 46. The output of the driving transformer is two high frequency square-wave signals from secondary windings of driving transformer 41 and 48, which are of the same value and opposite phase. The output terminals of the driving signal are identified as 41, 42, 43 and 44 on the module 90.
Bac~ to Figure 2, two serial transistors 51 and 52 compose an electronic switch 50. The terminals 41, 42, 43 and 44 are directly connected to emitters and bases of transistors 51 and 52, and the transistors 51 and 52 switch with the driving signals by turn. A high frequency square-wave voltage power of which frequency and voltage both vary with pulsation of pulsating DC voltage, with output from the emitter of transistor 51 going into the resonant circuit. The resonant circuit has two of the same resonant networks. Each resonant network has an inductor 61 (or 64) in series with a capacitor 62 (or 65), another capacitor 63 (or 66) in parallel with the lamp 71 (or 72) and the lamp 71 (or 72) is in series with the resonant network by way of its filaments. The resonant frequency of the network is designed near and higher than the maximal operating frequency of the electronic switch, and the frequency - output/input characteristic is the higher the operating frequency the greater the voltage rate of output/input. Therefore, when DC voltage between the DC lines 21 and 22 is on the increase, the oscillating frequency of the .
-; ,~
- ,. .
21~3~27 : :
module 90 is decreased. At output of electronic switch 50, the result is that the voltage is increased simultaneously with the decrease in frequency. 8ecause in the resonant circuit, the voltage rate of output/input is decreased with reduction of the operating frequency, when the voltage from electronic switch 50 is increased, which frequency is decreased and the output voltage is decreased to compare with the input voltage. In other words, the output voltage of the resonant circuit is stabilized. The voltage rate of output/input varies with the operating frequency that is usually not linear, and for gaining better compensation, the nonlinear corrector is used. If the frequency - output/input characteristic of resonant circuit is linear enough, the nonlinear corrector would not be used. The voltage-controlled oscillator 30 is the linear voltage-controlled oscillator 39.
Claims (4)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A variable frequency electronic ballast system having an AC
power source for actuating at least one gas discharge lamp, said ballast system comprising: a rectifying circuit is connected to said power source for supplying a full-wave rectified pulsating DC
voltage; a voltage-controlled oscillator is connected to said pulsating DC voltage for establishing a substantially varying high frequency oscillating signal; a driving circuit is connected to said oscillator for amplifying said signal; an electronic switch is connected to said driving circuit for providing a high frequency square-wave voltage power, said pulsating DC voltage is coupled to said electronic switch as a supply; a resonant circuit is linked between said electronic switch and said lamp for establishing a stabilized output-voltage.
power source for actuating at least one gas discharge lamp, said ballast system comprising: a rectifying circuit is connected to said power source for supplying a full-wave rectified pulsating DC
voltage; a voltage-controlled oscillator is connected to said pulsating DC voltage for establishing a substantially varying high frequency oscillating signal; a driving circuit is connected to said oscillator for amplifying said signal; an electronic switch is connected to said driving circuit for providing a high frequency square-wave voltage power, said pulsating DC voltage is coupled to said electronic switch as a supply; a resonant circuit is linked between said electronic switch and said lamp for establishing a stabilized output-voltage.
2. The ballast system as recited in claim 1 where said voltage-controlled oscillator includes a nonlinear corrector for changing relation of said pulsating DC voltage to frequency of said oscillating signal.
3. The ballast system as recited in claim 1 and claim 2 where said voltage-controlled oscillator and said driving circuit compose a module or an integrated circuit.
4. The ballast system as recited in claim 1 where said resonant circuit has two or more groups of output terminals for actuating same number of lamps.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002103627A CA2103627A1 (en) | 1993-08-09 | 1993-08-09 | Variable frequency electronic ballast of high power factor and stabilized output voltage |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002103627A CA2103627A1 (en) | 1993-08-09 | 1993-08-09 | Variable frequency electronic ballast of high power factor and stabilized output voltage |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2103627A1 true CA2103627A1 (en) | 1995-02-10 |
Family
ID=4152129
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002103627A Abandoned CA2103627A1 (en) | 1993-08-09 | 1993-08-09 | Variable frequency electronic ballast of high power factor and stabilized output voltage |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2103627A1 (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU732605B1 (en) * | 2000-06-14 | 2001-04-26 | Brenex Electrics Pty Limited | Control circuits for fluorescent tubes |
| FR2803977A1 (en) * | 2000-01-19 | 2001-07-20 | High Distrib | ELECTRIC APPARATUS, PARTICULARLY A FLUORESCENCE LIGHTING ELEMENT, HAVING A SUPPLY CIRCUIT COMPRISING A SERVO CONVERTER |
-
1993
- 1993-08-09 CA CA002103627A patent/CA2103627A1/en not_active Abandoned
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2803977A1 (en) * | 2000-01-19 | 2001-07-20 | High Distrib | ELECTRIC APPARATUS, PARTICULARLY A FLUORESCENCE LIGHTING ELEMENT, HAVING A SUPPLY CIRCUIT COMPRISING A SERVO CONVERTER |
| EP1119224A1 (en) * | 2000-01-19 | 2001-07-25 | High Distribution | Electrical device, in particular a fluorescent illuminating element, having a power source with a controlled converter |
| AU732605B1 (en) * | 2000-06-14 | 2001-04-26 | Brenex Electrics Pty Limited | Control circuits for fluorescent tubes |
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