CN2406448Y

CN2406448Y - Electronic ballast for fluorescent lamp

Info

Publication number: CN2406448Y
Application number: CN 99254953
Authority: CN
Inventors: 饶胜金
Original assignee: Individual
Current assignee: Individual
Priority date: 1999-12-09
Filing date: 1999-12-09
Publication date: 2000-11-15
Anticipated expiration: 2009-12-09

Abstract

The utility model relates to an electronic ballast for fluorescent lamps, which comprises a bridge rectifier circuit, a high-frequency inversion generation and control circuit, a lamp tube glow starting circuit, a follow current circuit which is connected to the front and the rear of the bridge rectifier circuit, a high-frequency feedback auxiliary power supply circuit introduced from high-frequency current, and an auxiliary oscillation circuit, for enhancing the power factor of the ballast and suppressing the harmonic interference of the current. Because the follow current circuit, the high-frequency feedback auxiliary power supply circuit and the auxiliary oscillation circuit are introduced, the input current is made to change as much as possible along with the input voltage. The power factor of the ballast is enhanced; simultaneously, the current harmonic interference obtains effective suppression. The contamination to electric networks is reduced; the power utilization safety is enhanced.

Description

Electronic ballast for fluoresent lamp

The utility model relates to a kind of ballast of fluorescent lamp, relates in particular to the electric ballast of fluorescent lamp.

Existing electronic ballast for fluoresent lamp all adopts interchange----direct current----exchange conversion, light fluorescent lamp by the high frequency electric source that civil power is transformed to tens of kilo hertzs, this electric ballast generally includes bridge rectifier, filter circuit, high frequency takes place and control circuit, and (see figure 1) such as fluorescent tube start-up circuit.But owing to adopted jumbo electrochemical capacitor (see figure 2) in the filter circuit, make that the angle of flow of bridge rectifier diode is very little, its current waveform is discontinuous pulse, thereby its power factor is very low, generally only is about 0.5 to 0.6.And the current harmonics of this kind ballast is very big, causes the pollution to electrical network easily, the normal operation of interfere with communications and other electrical equipment facilities.If a large amount of this kind ballasts that use in three phase supply, the current in middle wire in the circuit is very big with making, and the potential harm of safety formation to electrical network can cause unsafe factors such as fire.In addition, the electrical network surge current caused the puncture of ballast electronic component to damage to the impact of electric ballast easily when this ballast work fashion can not prevent that fluorescent lamp from turning on light.

The purpose of this utility model is to provide a kind of High Power Factor that has, and can reduce the Harmonic Interference to supply network, and can guarantee the electronic ballast for fluoresent lamp of Electrical Safety, to solve above-mentioned the deficiencies in the prior art, reaches real energy-conservation.

To achieve these goals, the utility model has designed a kind of electronic ballast for fluoresent lamp and has comprised: in order to civil power is converted to galvanic bridge rectifier, provide the high-frequency inversion of working power to take place and control circuit in order to described direct current is converted to high frequency electric source to fluorescent tube, in order to start the starting circuit of fluorescent tube; Also comprise being connected between bridge rectifier and high-frequency inversion generation and the control circuit, in order to power factor that improves ballast and freewheeling circuit and high frequency feedback auxiliary power circuit and the auxiliary oscillator circuit that suppresses the current harmonics interference.

Because electronic ballast for fluoresent lamp of the present utility model, freewheeling circuit and high frequency feedback auxiliary power circuit and auxiliary oscillator circuit behind bridge rectifier, have been added, thereby the angle of flow that makes rectifier diode increases and makes input current follow input voltage to greatest extent, improved the power factor of ballast, make the high-frequency inversion generation and the control circuit work of back level be in stable state simultaneously, and the Harmonic Interference of ballast has obtained effective inhibition, reduced pollution, improved Electrical Safety electrical network.Electronic ballast for fluoresent lamp of the present utility model in addition, owing to adopted freewheeling circuit and high frequency feedback auxiliary power circuit and auxiliary oscillator circuit, the reverse radio-frequency that has prevented the higher-order of oscillation is crosstalked, and makes the radio frequency conducted interference of ballast meet the standard that International Electrotechnical Commission (IEC) formulates.

Below with reference to drawings and Examples the utility model is described in further detail;

The circuit theory diagrams of the electronic ballast for fluoresent lamp of Fig. 1, prior art;

Fig. 2, be the sketch of bridge rectifier and filter circuit in the electronic ballast for fluoresent lamp shown in Figure 1;

The block diagram of Fig. 3, the utility model embodiment;

The circuit theory diagrams of Fig. 4, the utility model embodiment;

The current/voltage oscillogram of Fig. 5, the utility model embodiment;

As shown in Figure 3 and Figure 4, represent block diagram and circuit theory diagrams respectively according to the electronic ballast for fluoresent lamp of an embodiment of the present utility model.This electronic ballast for fluoresent lamp comprises bridge rectifier 1, freewheeling circuit 2, and high-frequency inversion takes place and control circuit 3, high frequency feedback auxiliary power circuit 5, auxiliary oscillator circuit 6, tube starting circuit 4.Freewheeling circuit 2 comprises 2a, 2b two parts, and freewheeling circuit 2a partly is connected to the input of bridge rectifier 1, and freewheeling circuit 2b partly is connected in the output of bridge rectifier 1; The output of freewheeling circuit 2 is connected to high-frequency inversion and takes place and control circuit 3; The input termination tube starting circuit 4 of high frequency feedback auxiliary power circuit 5, its output is connected to freewheeling circuit 2, and high-frequency inversion generation and control circuit 3 and auxiliary oscillating circuit 6 connect tube starting circuit 4.

Bridge rectifier 1 in the present embodiment, high-frequency inversion takes place and control circuit 3 and tube starting circuit 4, can use the circuit of prior art, it can constitute in the following manner: (one) bridge rectifier 1 comprises the bridge rectifier that diode D1 to D4 forms; (2) high-frequency inversion takes place and control circuit 3 comprises triode BG1, BG2, and resistance R 1 is to R4, capacitor C 3, C4, diode D5, diac DB3, transformer B; The primary coil n1 of transformer B, secondary coil n2, n3 are two groups of coils; Wherein resistance R 2 is connected to the collector and emitter of triode BG1, promptly between the C of Fig. 4 point and the D point; Resistance R 1, capacitor C 3, diode D5, diac DB3 constitute saw-toothed wave generator, and to produce the required starting of oscillation signal of high-frequency inversion generation circuit working, this circuit is connected between the base stage and ground end of C point, D point, triode BG2; The collector electrode of triode BG1 is connected to the C point, and emitter is connected to the D point, and base stage then is connected in the D point through resistance R 3, secondary coil n2; The collector electrode of triode BG2 is connected to the D point, and emitter is held with being connected to, and then via the resistance R 4 that is connected in series, secondary coil n3 holds base stage with being connected to; Capacitor C 4 is connected between D point and the ground end; The primary coil n1 of transformer B and inductance L 3 are connected between the pin of D point and fluorescent tube Y; (3) tube starting circuit 4 comprises the capacitor C 6 of cross-over connection between fluorescent tube Y two pins.

As previously mentioned, characteristics of the present utility model are: also be provided with freewheeling circuit 2 and high frequency feedback auxiliary power circuit 5 and auxiliary oscillator circuit 6.Freewheeling circuit 2 comprises inductance L 1, diode D6, inductance L 2, capacitor C 1, is connected to the AC end before inductance L 1 formation freewheeling circuit 2a places bridge rectifier 1; Diode D6, inductance L 2, capacitor C 1 series connection constitute freewheeling circuit 2b, are connected between the output terminals A point and G point (promptly holding) of bridge rectifier 1; High frequency feedback auxiliary power circuit 5 comprises diode D7, D8 and electrochemical capacitor C2, wherein diode D8 negative pole is connected to B point (inductance L 2 is connected in series a little with capacitor C 1), diode D8 is anodal to be connected in series in the F point with electrochemical capacitor C2 positive pole, and this point is connected with the pin of fluorescent tube Y, another utmost point of electrochemical capacitor C2 (being negative pole) is held (G point) with being connected to, diode D7 positive pole is connected to the B point, and negative pole is connected to the C point; Auxiliary oscillator circuit 6 comprises capacitor C 5, and this circuit is held between (G point) in the series connection point E and the ground of inductance L 3 and fluorescent tube Y one pin by capacitor C 5 cross-over connections.Among the embodiment, inductance L 2 is selected inductance value＞=5 milihenries; Capacitor C 1 is selected capacitance＞=47nF, and is withstand voltage＞=400v; Diode D6, D7, D8 select withstand voltage＞=400v; Diode D6, D7, D8 are fast recovery diode; Capacitor C 5 selection capacity＞=4N5, withstand voltage＞=1000v.

The adding of above-mentioned freewheeling circuit 2 and high frequency feedback auxiliary power circuit 5 and auxiliary oscillator circuit 6 makes the angle of flow of the diode D1 to D4 in the bridge rectifier 1 increase, thereby make the input current waveform of ballast be extended to half cycle nearly by original discontinuous spike, farthest follow input voltage, make it to approach sinusoidal waveform, as shown in Figure 5.Like this, can prevent that on the one hand the electrical network surge current can suppress the pollution of ballast current harmonics to electrical network on the other hand to the impact of ballast when fluorescent lamp from turning on light.According to the electronic ballast for fluoresent lamp of the utility model the foregoing description, its power factor can be up to more than 0.98, and its electric current total harmonic distortion THD is about 10%.

Above described only be a preferred embodiment of the present utility model, according to above-mentioned design of the present utility model, those skilled in the art also can make many variations and conversion to this, for example also high frequency feedback auxiliary power circuit of the present utility model can be inserted between bridge rectifier and the freewheeling circuit, in addition, freewheeling circuit of the present utility model and high frequency feedback auxiliary power circuit and auxiliary oscillator circuit also can apply in other various electric ballasts commonly used, but suchlike conversion all belongs to scope of the present utility model.

Claims

1, a kind of electronic ballast for fluoresent lamp, comprise: in order to civil power is converted to galvanic bridge rectifier 1, provide the high-frequency inversion of working power to take place and control circuit 3 and the tube starting circuit 4 lighted in order to the startup fluorescent tube in order to described direct current is converted to high frequency electric source to fluorescent tube, it is characterized in that: described electric ballast also comprises between connection bridge rectifier and high-frequency inversion generation and the control circuit 3, in order to power factor that improves ballast and freewheeling circuit 2 and high frequency feedback auxiliary power circuit 5 and the auxiliary oscillator circuit 6 that suppresses the current harmonics interference.

2, electronic ballast for fluoresent lamp as claimed in claim 1 is characterized in that: described freewheeling circuit 2 comprises inductance L 1, diode D6, inductance L 2, capacitor C 1, is connected to the AC end before inductance L 1 formation freewheeling circuit 2a places bridge rectifier 1; Diode D6, inductance L 2, capacitor C 1 series connection constitute freewheeling circuit 2b, are connected between the output terminals A point and G point (promptly holding) of bridge rectifier 1.

3, electronic ballast for fluoresent lamp as claimed in claim 1, it is characterized in that: described high frequency feedback auxiliary power circuit 5, comprise diode D7, D8 and electrochemical capacitor C2, wherein the negative pole of diode D8 is connected to the contact (B point) that inductance L 2 and diode D7 positive pole are connected in series mutually, its positive pole is connected in series in the F point with the positive pole of electrochemical capacitor C2 and this point is connected with the pin of fluorescent tube Y, the negative pole of diode D7 is connected to the C point of high-frequency inversion generation and control circuit 3, and electrochemical capacitor C2 negative pole is connected with ground end (G point).

4, electronic ballast for fluoresent lamp as claimed in claim 1 is characterized in that: the capacitor C 5 of described auxiliary oscillator circuit 6 is connected between the contact (E point) and ground end that inductance L 3 is connected with fluorescent tube Y one pin.