CN1051656A - High-efficiency electronic ballast - Google Patents

Abstract

A kind of low-pressure mercury fluorescent-lamp-use high-efficiency electronic ballast comprises current rectifying and wave filtering circuit and double-triode valve high-frequency oscillating circuits.In high-frequency oscillating circuits, be connected with high Q value series resonant tank, cancelled the negative feedback resistor of two transistor emitters in the oscillating circuit, cancelled in the circuit power supply heater circuit to filament.This electric ballast starting voltage low (line voltage is more than 30 volts), can prolonging lamp tube service life, economize on electricity, volume is little, in light weight, cost is low, can be used with the fluorescent tube of different capacity, can start and move many fluorescent lamps easily.

Description

High-efficiency electronic ballast

The present invention relates to a kind of high-efficiency electronic ballast, be mainly used in the starter and the operation of low-pressure mercury fluorescent lamp.

Existing illumination low-pressure mercury fluorescent lamp generally all is by the low-frequency ac power power supply, is for example powered by the 50Hz commercial ac power source.In the build-up of luminance and operation circuit of fluorescent lamp,, all be added with the peculiar ballast of arc discharge in order to make discharge stability.Use at present inductance type ballast the most widely, power consumption is many, cost is high, volume is big, heavy, must develop the better ballast of performance and replace it.Experimental result shows, is that the high-frequency ac power of 15-50KHz is powered to fluorescent lamp with frequency, has economize on electricity, build-up of luminance, luminous efficiency height, flicker free phenomenon and do not have advantage such as the hum of interchange fast.Since the middle nineteen seventies, the design of multiple high-frequency electronic ballast is disclosed, for example U.S. Pat 4188661(1979), Japan Patent J63170898(1988), Australian Patent Au8666834(1986) and Chinese patent CN88212514(1988) or the like.The disclosed circuit of electronic ballast of these documents differs from one another, but the part that all comes with some shortcomings, for example, high-frequency oscillating circuits and fluorescent lamp coupling are not good, cause fluorescent tube to be difficult to build-up of luminance and lamp tube service life shortening; The circuit structure complexity, the cost height; Same ballast can not be easily be used with the pipe of different size and power.

The object of the present invention is to provide a kind of high-efficiency electronic ballast, this electric ballast have with fluorescent lamp coupling is good, circuit structure is simple, cost is low, can prolonging lamp tube useful life, can be used, can start easily and move characteristics such as many fluorescent lamps with the fluorescent lamp of different capacity.

High-efficiency electronic ballast of the present invention is made up of current rectifying and wave filtering circuit and high-frequency oscillating circuits, and its circuit theory diagrams as shown in Figure 1.Rectification circuit is a bridge full-wave rectifier, is made up of four diodes of D1～D4.C1 is a filter capacitor.Oscillating circuit comprises that the parameter of transistor Q1, two pipes of Q2(of pair of series is identical), start loop R4, C3, D5(diac), series resonant tank L3, L4, C4, C5, fluorescent lamp T1 is connected on the two ends of C5.One end of this series resonant tank is connected with the collector electrode of Q2 by L3, and the other end is connected with dc power anode by C4.The quality factor q of series resonant tank is higher,

$Q\≅\frac{1}{R}\sqrt{\frac{L}{C_s}}$

, in the formula, L=L3+L4, R are the resistance value of inductance.Be connected with between the emitter of every triode and the base stage and drive inductance L 1(or L2) and current-limiting resistance R1(or R2).Drive inductance L 1, L2 and L3 on same magnet ring.The emitter of triode Q2 directly is connected with the negative pole of DC power supply, and the emitter of Q1 directly is connected with the collector electrode of Q2, has promptly cancelled the negative feedback resistor of two high-frequency high-power transistor emitters in the oscillating circuit.With the respectively short circuit of fluorescent tube T1 two ends filament, promptly cancelled in the circuit power supply heater circuit to filament.The end of fluorescent tube T1 is connected with an end of capacitor C 4, and the other end of C4 is connected with the positive pole of DC power supply; The other end of fluorescent tube T1 is connected with an end of inductance L 4, and the other end of L4 links to each other with L3.

Identical triode Q1 and the Q2 of two parameters used in the circuit is Bu406, and they form vibration, rate of doing work output again.Behind the power connection,, produce the direct voltage of about 300V through bridge full-wave rectifier and filtering, in the moment of power connection, the series resonant tank storage power.Because the charge constant of R4, C3 is bigger, the C3 both end voltage rises slower, and when the C3 charging reached the puncture voltage of diac D5, a narrow current impulse was added to the base stage of Q2, make the Q2 conducting, this moment, the charge volume of series resonant tank formed the loop discharge through collector electrode, the emitter of Q2.When discharging current passed through inductance L 3, because L3 on the toroidal core coil and the coupling of L1 and L2 make the Q1 conducting, Q2 ended, and power supply charges to series resonant tank.Two pipes take turns conducting, make the oscillating circuit starting of oscillation.When starting of oscillation, oscillating circuit is with the hunting of frequency of about 23KHz, and produces high pressure on capacitor C 5.Under the effect of very high oscillating voltage, fluorescent lamp build-up of luminance and operation.After rated operational current passed through fluorescent tube, the impedance of fluorescent tube descended greatly, and to series resonant tank Q value is descended, resonance frequency is reduced to about 18KHz(when fluorescent lamp is the power saving fluorescent lamp of 11W).After oscillating circuit was realized constant amplitude stable oscillation stationary vibration, its oscillation frequency remained on this operating frequency always.In the circuit, L4 is 2-15mH, and C4 is 0.02-0.04 μ F, C5 is the pipe of 3000-10000PF(different capacity, capacitance difference in parallel, the electric capacity of high-power fluorescent tube parallel connection is bigger), C2 is 4000-6000PF, R3 is 200-470K Ω, and C3 is 0.01-0.05 μ F, and R4 is 270K Ω, R1, R2 are 8.2 Ω, on the annular FERRITE CORE, L1, L2 are 3 circles jointly for L1, L2 and L3, and L3 is 10 circles.

Disclosed high-frequency electronic ballast circuit, some circuit (for example Chinese patent CN88207905) also are to adopt this triode LC oscillating circuit.The emitter of two triodes all is connected in series negative feedback resistor in this circuit.Negative-feedback circuit has the effect that reduces the oscillating circuit output amplitude.When reality was used, it can influence the build-up of luminance of fluorescent tube.

In order both to improve the starting performance of electric ballast, do not reduce its stability and reliability again, the present invention is in the cancellation negative feedback resistor, on circuit with the short circuit of lamp tube ends filament, be about to this non-linear element of scorching hot filament and from series resonant circuit, remove, make resonant circuit more stable.This circuit has been given full play to the nonlinear characteristic of fluorescent tube ionic medium body behind the fluorescent tube starter to the self-oscillatory stabilization of oscillating circuit.Entire circuit is before tube starting, and self-oscillatory amplitude is dull to rise, and can not tend towards stability; Behind tube starting, multiple factors such as the NONLINEAR NEGATIVE RESISTANCE characteristic of fluorescent tube make amplitude and frequency of oscillation be in a kind of stable state.When voltage disturbance occurring in the circuit, the variation of electric current can not influence the amplitude of transistor base driving voltage in the fluorescent tube, cause the oscillating voltage amplitude of triode Q2 collector electrode to remain unchanged substantially, thereby the voltage of guaranteeing lamp tube ends remains unchanged, and promptly this circuit has good stable and reliability.

In this circuit, fluorescent tube is connected in the circuit as a non-linear element of oscillating circuit.After the circuit energized, sharply the high frequency voltage amplitude that rises produces enough high-frequency electric fields and makes the rapid build-up of luminance of fluorescent tube, and behind the build-up of luminance, the nonlinear characteristic of fluorescent tube and the inherent characteristic of circuit tend towards stability circuit.Because the steady-working state (frequency of oscillation, oscillation amplitude etc.) that circuit is last and the characteristic relation of fluorescent tube are very close, therefore can make lamp works in the optimum Working that self determined, realized the matched well between fluorescent tube and oscillating circuit, and make circuit have unique adaptive ability, as long as promptly be no more than the power upper limit (can determine) of this circuit, must do not adjust circuit parameter and just can be used with the low-pressure mercury fluorescent lamp of various different sizes and different capacity by the triode of selecting different capacity.For example, need not circuit parameter is adjusted, only change the capacitance of the capacitor C 5 in parallel with fluorescent tube, electric ballast of the present invention just can start and move the power saving fluorescent lamp of multiple models such as 9W, 11W, 16W, 36W and power, also can move common fluorescent lamps such as 8W, 12W, 20W, 30W, 40W.These characteristics bring many conveniences for the manufacturer and the user of electric ballast, and help the target that this ballast is realized commercialization.

The emission of the electronics of fluorescent tube electrode all has significant effects to the characteristics such as starting, life-span (also being related to the pipe end melanism) and noise of lamp.Existing circuit of electronic ballast for improving the starting characteristic of fluorescent tube, generally all be provided with the circuit to the filament heating, but this heater circuit often makes filament be connected in the resonant circuit of oscillator, influences the stable operation of oscillator.The present invention has cancelled the filament heating, has not only simplified circuit, and export license is reduced, and has prolonged the life-span of fluorescent tube, the noise that also helps the stable of resonant circuit work and reduce to produce owing near the ion vibration filament.This circuit is in when operation, and fluorescent tube just can build-up of luminance when supply voltage was 30 volts, this be because cancel that the Q value of transistor emitter resistance, series resonant circuit is higher, the result of combined factors effect such as the configuration of each element of resonant circuit and parameter designing are reasonable.

The luminous efficiency of fluorescent lamp, relevant with many factors.The tube wall temperature of fluorescent tube (pressure that relates to mercuryvapour in the pipe) has direct influence to luminous efficiency.The output of the light of fluorescent lamp changes with the variation of tube wall temperature, and when tube wall temperature was below or above 40 ℃ of optimum temperatures, the light output of lamp all can reduce.Test result shows, is connected in the fluorescent lamp in Fig. 1 circuit, and tube wall temperature is about 40 ℃ (when ambient temperature is 15 ℃～25 ℃), so the luminous efficiency of lamp is very high.In general, the characteristic of ballast is bigger to the efficient (1m/W) and the life-span influence of fluorescent lamp, and for example the life-span of lamp descends along with the increase of lamp current peak factor.Because circuit of electronic ballast parameter designing of the present invention is reasonable, also cause the luminous efficiency of lamp to improve and life-time dilatation.Be connected in the fluorescent tube in this circuit, when doing the switch life test, the switch number of times reaches (the general fluorescent switch life-span is 8000 times) more than 20,000 times.

Electric ballast is operated in tens kilo hertzs high frequency, and its radio interference noise is higher.In circuit of the present invention, the high-frequency current waveform that flows through fluorescent tube is bordering on sine wave, and this operating state tends to make the high-frequency noise of circuit to reduce to minimum; Filter capacitor C1 in the circuit had both played the power supply filter action, can partly filter the noise that is produced by oscillating circuit again.Characteristics on these circuit design make that the existing fluorescent lamp noise of inductance type ballast that uses of the interference-to-noise ratio of this circuit is much lower.

Circuit as shown in Figure 1 not only has unique adaptive ability, and can also be used with two or many fluorescent tubes, has solved the difficult problem that an electric ballast starts and move many fluorescent lamps easily.Second method of attachment of fluorescent tube T2 in circuit is: C ' is 5=C5) in parallel for its capacitance of fluorescent tube T2 and C ' 5(, two ends filament short circuit, the end of T2 4=C4) links to each other with the positive pole of power supply through C ' 4(capacitance C ', and the other end of T2 4=L4) is connected with the end of L3 through L ' 4(inductance value L '.If T2 is the pipe with the same power of T1, after T2 is connected into circuit, just build-up of luminance immediately, and normal operation.Can be connected into the 3rd fluorescent tube, the 4th fluorescent tube with aforesaid way ... this connection, easy for installation, simple.

The performance of electric ballast and design of the distribution of circuit and the configuration of components and parts in printed substrate concern very close.The components and parts of entire circuit of the present invention reasonably are arranged in 20 * 90mm printed substrate, have improved the stability and the reliability of circuit operation effectively.Electric ballast of the present invention, than with inductance type ballast economize on electricity more than 30%, more about 5% than economizing on electricity with existing high-frequency electronic ballast, volume is little, in light weight, power consumption 1-2W, is convenient to maintenance, and cost is greatly reduction also.

Claims (5)

1, a kind of high-efficiency electronic ballast, form by current rectifying and wave filtering circuit and high-frequency oscillating circuits, high-frequency oscillating circuits comprises two triodes that parameter is identical, start loop and series resonant tank, it is characterized in that having the series resonant tank (L3 of higher resonant tank quality factor q, L4, C5, C4) a end is connected through the collector electrode of inductance L 3 with triode Q2, the other end is connected with the positive pole of DC power supply through capacitor C 4, the emitter of high-frequency high-power triode Q2 directly is connected with the negative pole of DC power supply, the emitter of triode Q1 directly is connected with the collector electrode of Q2, has promptly cancelled the negative feedback resistor of two transistor emitters in the high-frequency oscillating circuits; With the respectively short circuit of fluorescent lamp T1 two ends filament, promptly cancelled in the circuit power supply heater circuit to filament; Fluorescent tube T1 is in parallel with C5, and the end of T1 is connected with an end of capacitor C 4, and the other end of fluorescent tube T1 is connected with an end of inductance L 4, and the other end of L4 is connected with L3.

2, according to the described high-efficiency electronic ballast of claim 1, the inductance value that it is characterized in that L4 in the series resonant tank is 2-15mH, the electric capacity of C5 is 3000-10000PF, and the electric capacity of C4 is 0.02-0.04 μ F, and triode Q1, Q2 are high-power high-frequency transistor BU406.

3, according to the described high-efficiency electronic ballast of claim 2, it is characterized in that in the circuit inductance L 1, L2 and L3 jointly on same annular ferrite core, L1, L2 are all 3 circles, and L3 is 10 circles.

4, according to the described high-efficiency electronic ballast of claim 3, it is characterized in that the R3 in the circuit is 200K Ω-470K Ω, C2 is 4000-6000PF.

5, according to the described high-efficiency electronic ballast of claim 4, it is characterized in that this electric ballast can start and move many fluorescent lamps, its concrete connection is: with the filament short circuit at second fluorescent tube T2 two ends and in parallel with capacitor C ' 5 (capacitance C ' 5=C5), the end of T2 4=C4) links to each other with the positive pole of DC power supply through C ' 4(capacitance C ', the other end of T2 4=L4) links to each other other fluorescent lamp T3, T4 through L ' 4(inductance value L ' with L3 ... can be connected in the circuit by the same manner.