CN1023627C - Electronic ballast of fluorescent lamp with current follow-up circuit - Google Patents

Abstract

The present invention relates to an electronic ballast with a current follow-up circuit for fluorescent lamps. A main current follow-up circuit which is composed of two capacitors and three diodes is connected between a bridge rectifier of a common electronic ballast and a high frequency generating and controlling circuit; a matched auxiliary current follow-up circuit, together with a double-pi common-mode rejection high-frequency filter circuit that is composed of two capacitors and two inductors, is connected in series between the bridge rectifier and an input end of an AC power supply, and the other capacitor is connected in parallel between a positive and a negative DC output ends of the bridge rectifier. Due to the adoption of the follow-up circuit in the electronic ballast, the three-phase neutral current is small, the circuit power factor is increased, the harmonic interference toward electric networks is reduced, the capability of resisting the overvoltage of a power supply is enhanced, and the reliability of the electronic ballast is greatly improved.

Description

Electronic ballast of fluorescent lamp with current follow-up circuit

The invention belongs to electronic technology field, is a kind of electronic ballast for fluoresent lamp.

Electric ballast at present commonly used all is by AC-DC-exchange conversion, promptly comes the burning-point fluorescent tube by the frequency conversion ballast technology.Be used for 220V, the 50HZ civil power in friendship-straight conversion, generally all adopts the circuit (as shown in Figure 1) of half-wave or full-wave rectification, big dielectric capacitance Lu ripple.Because the existence of big capacity Lu ripple capacitor C makes rectifier diode D ₁～D ₄The angle of flow very little, line current i forms spike, as shown in Figure 2.After three-phase uses electronic energy-saving lamp (as shown in Figure 3) simultaneously, the current in middle wire i of its circuit as shown in Figure 4, every phase current is discontinuous pulse, phase difference 120 degree, the source current waveform difference, harmonic content is big, thereby, even when electronic energy-saving lamp was used in three-phase equilibrium, current in middle wire was also non-vanishing, but for the three-phase current sum.And when its current in middle wire i is as shown in Figure 6 when (as shown in Figure 5) at three alternate while burning-point incandescent lamps or Inductive ballast electricity-saving lamp, because three-phase current is continuous sine wave, and phase difference is 120 degree, and stack result is cancelled out each other, its effective value center line average electric current approximate zero.Therefore, though present electric ballast has energy-efficient good result, have following deficiency for above-mentioned reasons: when three-phase used a large amount of electronic energy-saving lamp simultaneously, current in middle wire was very big, to cause the tripping operation (blown out) of electric power system, the serious fire that causes; And start simultaneously when a large amount of electronic fluorescent lamps, electric ballast in blocks might puncture and burns.In addition, general electric ballast power factor is not high enough, is about 0.6, and seriously polluted to the Harmonic Interference of supply network.

The purpose of this invention is to provide a kind of defeated supply line fail safe that improves, reduce the supply network Harmonic Interference, and can improve the efficient energy-saving fluorescent lamp electronic ballast of power factor (PF).

This electric ballast comprises electronic circuit and package casing thereof, and they have constituted an integral body.The electronic circuit of at present common efficient energy-saving fluorescent lamp electronic ballast comprises that bridge rectifier, filter circuit, high frequency take place and the several essential parts of control circuit.The electric ballast that has in addition also has " abnormal state protection circuit " and " preheat starting circuit ".Wherein filter circuit uses big electric dielectric device C.The characteristics of this electric ballast are, bridge rectifier and high frequency takes place and control circuit between used a main current follow-up circuit, correspondingly between the AC power input of bridge rectifier and dc output end, used an auxilliary current follow-up circuit.Removed the big dielectric capacitance C in the primary electron ballast like this.Fig. 7 is the circuit block diagram of this electric ballast.Wherein 1 is auxilliary current follow-up circuit, and 2 for bridge rectifier, 3 is main current follow-up circuit, and 4 is preheat starting circuit, and 5 for high frequency takes place and control circuit, and 6 is abnormal state protection circuit, R ₁Be fluorescent tube.The circuit 6 that dashed rectangle is represented can adopt, and also can not adopt.

Fig. 8 is a concrete line map of this electric ballast.Wherein, diode D ₁～D ₄Form bridge rectifier 2, resistance R ₁～R ₇, capacitor C ₃～C ₇, inductance L ₃～L ₆, triode BG ₁, BG ₂, diode D ₃, D ₇Form high frequency capacitor C takes place and control circuit 5 ₆, C ₉Form preheat starting circuit 4,6 with PTC and be abnormal state protection circuit commonly used.R ₂It is fluorescent tube.Its circuit connects as common electric ballast.By capacitor C ₃, C ₄With diode D ₅, D ₆, D ₇Form main current follow-up circuit 3.Capacitor C ₆, C ₁, C ₂And inductance L ₁, L ₂Form auxilliary current follow-up circuit.Concrete circuit connects as follows: diode D ₅, D ₆, D ₇Series connection, D ₈Both positive and negative polarity respectively with D ₇Negative pole, D ₅Positive pole connect C ₄Both positive and negative polarity respectively with D ₅Negative pole, D ₇Positive pole connect D ₅Negative pole and D ₇Anodal respectively again with by D ₁～D ₄The bridge rectifier current DC voltage output positive and negative terminal of forming connects.This kind connection makes rectifier diode D ₁～D ₄The angle of flow increase, thereby the waveform of line current i trends towards continuously by original spike, near sinusoidal waveform (as Fig. 9), and can reduce surge current.In the auxilliary accordingly current follow-up circuit of main current follow-up circuit, C ₃, C ₁And L ₁, L ₂Form two π common mode inhibition high-frequency filter circuits, C ₂Be connected in parallel between the bridge rectifier direct voltage output positive and negative terminal, they are in order to reduce surge current, to suppress Harmonic Interference and to high frequency bypass.Very obvious, to adopt after the current follow-up circuit, new variation has appearred in the state of electric ballast entire circuit: the waveform trend of line current i is continuous, and the surge current when circuit is opened obviously reduces, and the direct voltage E behind the stream is pursued in rectification _eReduce, after load is connected between the half-bridge, make triode BG ₁, BG ₂Only bear the voltage of EC/2.Thereby, adopting the later electric ballast of current follow-up circuit, the three-phase current in middle wire is very little, the line power factor obviously improves, and the Harmonic Interference of electrical network is significantly reduced, and the requirement of withstand voltage of triode is reduced, anti-power supply overvoltage capabilities strengthens, and the reliability of electric ballast greatly improves.

In this electric ballast, the desirable following ranges of the component parameters of current follow-up circuit, C ₅And C ₄: 0.47 μ F/250V～4.7 μ F/250V, D ₅～D ₇: anti-TV university is in the diode of 300V, C ₄=C ₁: 0.047 μ F/400V～0.47 μ F/400V, C ₂: 0.1 μ F/400V～0.68 μ F/400V, L ₁=L ₂: greater than 10mH.The component parameters scope of application of other circuit such as common electric ballast.Because C ₅, C ₄Capacity and the filter capacitor C in the original electric ballast of withstand voltage ratio little, so the price than C is low on the contrary for the element price of main current follow-up circuit, and compare C ₃, C ₄Choose greater than the performance of 4.7 μ F/250V more goodly, surge is littler, and electronic energy-saving lamp burns out better effects if in flakes when preventing that three-phase from starting simultaneously.

The main current follow-up circuit of this electric ballast can constitute (as shown in figure 10), its better effects if with two utmost point current follow-up circuits.C wherein ₃, C ₄, D ₅, D ₆, D ₇Form one-level, C ^' ₃, C ^' ₄, D ^' ₅, D ^' ₆, D ^' ₇Form the second level.

Current follow-up circuit in this electric ballast can use on various electronic ballast circuits commonly used, can both obtain same effect.

This electric ballast has following premium properties: reduce the current in middle wire when three-phase uses electronic energy-saving fluorescent simultaneously greatly, improve the fail safe of defeated supply line; When three-phase starts electronic energy-saving lamp simultaneously, can avoid burning in flakes of electric ballast; The merit factor of circuit significantly improves, and generally can reach the requirement of High Power Factor (〉=0.85) electric ballast; Harmonic Interference to supply network significantly reduces.

Embodiment: with 40 watts of electric ballasts is example.Its electronic circuit such as Fig. 8, wherein the component parameters value of main current follow-up circuit is: C ₃=2.2 μ F/250V, C ₄=1 μ F/250V, D ₅=D ₆=D ₇=1N40004, the component parameters value of auxilliary current follow-up circuit is: C ₀=C ₁=0.1 μ F/400V, C ₂=0.47 μ F/400V, L ₁=L ₂=30mH.Abnormal state protection circuit is a general circuit; can add and not add; the circuit parameter value of other parts such as common 40 watts of electric ballasts; such as EB-III type automatic bias auto-excitation type electric ballast circuit (" fail-safe analysis of electric ballast "; Yang Genyuan etc.,＜electric light source〉the 5th phase of nineteen ninety).By common mode, after the installation in the enclosure, promptly get 40 watts novel electron ballast.

Fig. 1 is the commutation capacitor filter circuit of ordinary electronic ballast, and A is that A phase line 0 is center line

Ec is a direct voltage.

Fig. 2 is the line current waveform of single-phase rectifier filter circuit, and ω t is the angular frequency time shaft.

Fig. 3 uses the electronic energy-saving lamp schematic circuit diagram simultaneously for three-phase, and wherein 7 is electricity-saving lamp.

A, B, C are three tunnel phase lines, and 0 is center line.

Line midline current waveform when Fig. 4 uses electronic energy-saving lamp simultaneously for three-phase.

Schematic circuit diagram when Fig. 5 uses incandescent lamp simultaneously for three-phase, wherein 8 is incandescent lamp.

Line midline current waveform when Fig. 6 uses incandescent lamp simultaneously for three-phase.

Fig. 7 is this electric ballast electronic circuit block diagram.

Fig. 8 is the electrical schematic diagram of this electric ballast, and F is a fuse.

Fig. 9 is the line current waveform of this electric ballast.

Figure 10 is the electric ballast electrical schematic diagram (high frequency takes place and control circuit omits) that has two utmost point current follow-up circuits.

Claims (3)

1, a kind of electric ballast, its electronic circuit comprises that bridge rectifier, high frequency take place and control circuit, it is characterized in that between bridge rectifier and high frequency generation and control circuit, also having a main current follow-up circuit, correspondingly also have an auxilliary current follow-up circuit between the interchange input of bridge rectifier and dc output end, main current follow-up circuit is by capacitor C ₃, C ₄With diode D ₅, F ₆, D ₇Form, its circuit connects as follows; Diode D ₅, D ₆, D ₇Series connection, D ₆Both positive and negative polarity respectively with D ₇Negative pole, D ₅Positive pole connect C ₃Both positive and negative polarity respectively with D ₅Negative pole, D ₅Positive pole connect C ₄Both positive and negative polarity respectively with D ₆Negative pole, D ₇Anodal connection, D ₅Negative pole and D ₇Anodal respectively again with by D ₁-C ₄The positive and negative terminal of the bridge rectifier direct voltage output of forming connects, auxilliary current follow-up circuit correspondingly, by capacitor C ₀, C ₁And inductance L ₁, L ₂Form two π common mode inhibition high-frequency filter circuits, capacitor C ₂Be connected in parallel between the positive and negative terminal of bridge rectifier direct voltage output.

2, electric ballast according to claim 1 is characterized in that said main current follow-up circuit is two utmost point current follow-up circuits, by capacitor C ₃, C ₄, diode D ₅, D ₆, D ₇Form one-level, capacitor C ₃, C ₄, diode D ₅, D ₆, D ₇Form another level.

3, according to claim 1,2 described electric ballast, it is characterized by major-minor current follow-up circuit component parameters scope and be: C ₃, C ₄: 0.47 μ F/250V～4.7 μ F/250V, D ₅～D ₇: the diode that withstand voltage 300V is above, C ₀=C ₁: 0.047 μ F/400V～0.47 μ F/400V; C ₂: 0.1 μ F/400V～0.68 μ F/400V, L ₁=L ₂: greater than 10mH.

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