CN2430827Y

CN2430827Y - Electronic ballast

Info

Publication number: CN2430827Y
Application number: CN 00233862
Authority: CN
Inventors: 朱益杉
Original assignee: Guoqi Electronics Co ltd
Current assignee: Hon Hai Precision Industry Co Ltd
Priority date: 2000-05-15
Filing date: 2000-05-15
Publication date: 2001-05-16
Anticipated expiration: 2010-05-15

Abstract

The utility model relates to a high efficiency electronic ballast of a single-order conversion. The electronic ballast is composed of a push-pull type resonance level, a lamp tube, a synchronous pulse width modulator, and a bidirectional impedance converter; the input terminal of the push-pull type resonance level is connected with a power supply, and a secondary winding of a high frequency transformer of the push-pull type resonance level directly drives the lamp tube; the lamp tube, the synchronous pulse width modulator and the bidirectional impedance converter form a series connection loop; the output terminal of the bidirectional impedance converter is connected in series with the secondary winding of the high frequency transformer of the push-pull type resonance level. The utility model uses the bidirectional impedance converter to replace a traditional power converter, and the bidirectional impedance converter is positioned on the secondary side of a transformer. The utility model only passes through a resonance level and single-order loss and has the advantages of low power, low thermal loss, and low cost.

Description

Electronic ballast

The utility model relates to a kind of electronic ballast, refers to a kind of high efficiency electronic ballast of single-order conversion especially.

As shown in Figure 3, Figure 4, at present, the electronic ballast that is used with fluorescent lamp is: the push-pull type resonance level of being made up of the high frequency transformer and the two transistor of high turn ratio 50, produce sine wave by the self-excitation mode, change the alternating voltage of high voltage low current again through the high frequency transformer of high turn ratio into, excite fluorescent tube 60 to light.Yet the electronic ballast of this structure can only be exported the voltage of certain volt value, can't control (that is: the light and shade of control fluorescent tube) to lamp tube current.So, for addressing this problem, people are connected in series a power converter 80 again at the front end of push-pull type resonance level 50 usually, change the transistor turns cycle (DUTY CYCLE) of these power converter 80 inside by clock-pulse width modulator 70 (PWM ControIler), reach and adjust, obtain the control of brightness by the lamp tube current size.

This method, though can solve the problem that changes lighting tube brightness,, bring new problem again, promptly cause efficient to reduce greatly, do not meet high efficiency requirement.Owing to between the fluorescent tube 60, must be connected in series power converter 80 and push-pull type resonance level 50 at power input, thereby cause the quadratic loss of power.If the efficient of aforementioned each grade is 85% o'clock, gross efficiency after the two-stage serial connection is about 72%, and power converter 80 is serially connected on the major loop, transistor in the power converter 80 must use high-power, big current transistor, cost heat higher, that produce is bigger, so no matter previous designs is aspect efficient, cost, still on heat dissipation problem, all not very desirable, truly have the necessity that is improved.

Main purpose of the present utility model provides the high efficiency electronic ballast of the single-order conversion of a kind of low cost, the loss of low-heat energy.

For achieving the above object, the utility model is by the following technical solutions: a kind of electronic ballast, comprise: a push-pull type resonance level, constitute self-excited oscillation type AC boosting loop by high frequency transformer and transistor, its input links to each other with power supply, and the secondary winding of its high frequency transformer directly drives fluorescent tube;

One lock-out pulse width modulator, its input links to each other with the other end of fluorescent tube, and the signal of sampling fluorescent tube end is with the voltage of control lamp tube ends;

One transducer, this transducer is the bilateral impedance transducer that is made of transistor, the controllable current two-way flow, its input is connected with the output of described clock-pulse width modulator, its output is serially connected on the secondary winding of described push-pull type resonance level great number transformer, and constitutes series loop with fluorescent tube, clock-pulse width modulator.

Described transducer and fluorescent tube are connected on the different end points of described high frequency transformer secondary winding or on the fluorescent tube loop; Described transducer is with two transistor connection parallel with one another, and between the base stage of two transistor the cross-over connection inverter; Described transistorized two ends cross-over connection has compensation condenser; Described transistor collector is serially connected with rectifier diode.

Because the utility model is at the output transformer secondary side, replace the power converter that is connected in series at the input mains side in the conventional art with the bilateral impedance transducer, make and only pass through resonance level on the lamp tube power supply path, the loss of single-stage is only arranged, like this except that obtaining the high efficiency, more, overcome the bad problem that traditional electrical minor ballast efficient is low, cost is high because the bilateral impedance converter configurations in the Circuit Fault on Secondary Transformer of low current, can reduce the wastage and cost.

In addition, the utility model moves to the bilateral impedance transducer secondary side (outlet side) of high frequency transformer, change the size of current of secondary side, these variations, make power input between the fluorescent tube, single-stage conversion and single switch cost, the characteristic that Circuit Fault on Secondary Transformer only has low current to flow are only arranged for keeping, only need use low cost, ordinary appliances element to get final product, and the heating phenomenon obviously reduce.

Again, the utility model is except the installation site that changes the power converter, its internal structure also has significantly change, change into the anti-phase connection of two transistor and form the bilateral impedance transducer, its switching frequency more designs and push-pull type resonance level synchronous (Synchronization), and near close phase angle zero degree, switch (zero switching), make and flow through lamp tube current convergence sine wave, to improve luminous efficiency and to pass through suitable compensation electric capacity, make transducer conducting and by the time, output voltage and lamp current are compensated, have auxiliary its output waveform and more tend to sinusoidal wave effect.

Further specify below in conjunction with accompanying drawing.

Fig. 1: be structure calcspar of the present utility model.

Fig. 2: be the utility model detailed circuit diagram.

Fig. 3: be the traditional structure calcspar.

Fig. 4: be the traditional structure detailed circuit diagram.

As Fig. 1, shown in Figure 3, the utility model mainly is made of push-pull type resonance level 50, fluorescent tube 60, bilateral impedance transducer 10 and pulse-width modulator 70; The input of push-pull type resonance level 50 links to each other with power supply, and an end of fluorescent tube 60 directly links to each other with the high frequency transformer secondary side of push-pull type resonance level 50, constitutes the major loop of power supply; The other end of fluorescent tube 60 links to each other with the input of pulse-width modulator 70, the output of pulse-width modulator 70 links to each other with the input of bilateral impedance transducer 10, and the output of bilateral impedance transducer 10 links to each other with the high frequency transformer secondary side of push-pull type resonance level 50.As seen from the figure, the utility model is compared and can be found with traditional electrical minor ballast, and the utility model has mainly omitted traditional power converter, and is configured on fluorescent tube institute 60, the transformer secondary side position with a two-way impedance transducer 10.Efficient with this structural design, because of being parallel to push-pull type resonance level 50, only push-pull type resonance level 50 outputs are directly linked to each other with fluorescent tube 60 through transformer, bilateral impedance transducer 10 is not serially connected on the major loop, make power input to the loop between the fluorescent tube 60, only there is push-pull type resonance level 50, so import power supply to the single-order loss that push-pull type resonance level 50 is only arranged between the fluorescent tube 60, and the utility model bilateral impedance transducer 10 is configured in only to be had in mobile fluorescent tube 60 loops of little electric current, the feasible magnitude of current by transducer 10 significantly reduces, by contrast, not only the element cost can reduce, and switch cost also reduces relatively, makes that the efficient of this transducer 10 can be up to 99%, if the efficient of this push-pull type resonance level 50 is when 85% left and right sides, the gross efficiency of this structural design also maintains about 84%.Must compare through the loss of two class large powers with traditional structure, the utlity model has greater efficiency.

In addition, the structure of the utility model bilateral impedance transducer is also completely different with traditional structure, non-merely with traditional power converter 80 shift positions, its internal structure is completely different, for example: conventional power converter 10 is an one-way operation, and the utility model is the structure of a two-way running.

As shown in Figure 1 and Figure 2, the structure of the utility model push-pull type resonance level 50 and clock-pulse width modulator 70 is all identical with traditional structure, and difference is:

The utility model bilateral impedance transducer 10 is made of two

transistor

12,13,

diode

14,15, inverter 11, power supply 16 and compensation condenser 17.Two

transistor

12,13 is with in parallel again after two

diodes

14,15 are connected respectively; The base stage of two

transistor

12,13 is by resistance R 2, R3 cross-over connection inverter 11; The emitter-base bandgap grading of two

transistor

12,13 connects a power supply 16, constitutes one and can make two

transistor

12,13 conductings simultaneously or by, transducer that can two-way running; Cross-over connection one compensation condenser 17 between aforementioned two transistor to reduce pulse voltage and to relax the current waveform distortion, makes current waveform slightly be sinusoidal wave.After the input of bilateral impedance transducer 10 connects clock-pulse width modulator 70, can be according to the handover operation of the pulse signal oxide-semiconductor control transistors of sending into, and can the magnitude of current that flow through be changed along with the variation of input pulse width.These bilateral impedance transducer 10 upper ends (output) are serially connected in the secondary winding position of the high frequency transformer 51 of push-pull type resonance level 50, constitute the loop of connecting with the fluorescent tube 60 that is connected this secondary winding equally, so this bilateral impedance transducer 10 is under the state of being connected in series with fluorescent tube 60, can realize changing the purpose of fluorescent tube 60 electric currents.

As shown in Figure 2, the operating voltage of fluorescent tube 60 is high voltage, the low current voltage of self-oscillation after the high frequency transformer conversion by push-pull type resonance level 50 fully, and does not need through 10 supplies of bilateral impedance transducer.Bilateral impedance transducer 10 only is a passive type, can changes the flow restricter of impedance in this circuit.Therefore, at power input to transistor switch cost (producing) once only between the fluorescent tube 60 by the push-pull type resonance level, and, this bilateral impedance transducer 10 only has on fluorescent tube 60 loops that small amount of current flows through because being connected, handoff loss more can significantly reduce, and factors such as the lower cost of little current transistor element and heat energy loss are low, the efficient of this bilateral impedance transducer 10 is up to about 99%, with efficient be that 85% push-pull type resonance level 50 formed gross efficiency values are about about 84%, maintain the efficient level that single-stage push-pull type resonance level 50 is only arranged substantially.

In sum, the utility model provides a kind of only the transition loss of single transistor, and can change the electronic ballast of output current, has reduced cost and thermal dissipation.

Claims

1. electronic ballast comprises:

One push-pull type resonance level constitutes self-excited oscillation type AC boosting loop by high frequency transformer and transistor, and its input links to each other with power supply, and the secondary winding of its high frequency transformer directly drives fluorescent tube;

It is characterized in that: also comprise:

2. electronic ballast as claimed in claim 1 is characterized in that: described transducer and fluorescent tube are connected on the different end points of described high frequency transformer secondary winding or on the fluorescent tube loop.

3. electronic ballast as claimed in claim 1 is characterized in that: described transducer is with two transistor connection parallel with one another, and between the base stage of two transistor the cross-over connection inverter.

4. as claim 1 or 3 described electronic ballasts, it is characterized in that: described transistorized two ends cross-over connection has compensation condenser.

5. as claim 1 or 3 described electronic ballasts, it is characterized in that: described transistor collector is serially connected with rectifier diode.