CN1192646A

CN1192646A - Electronic ballast for fluorescent lamp

Info

Publication number: CN1192646A
Application number: CN96119956A
Authority: CN
Inventors: 胡安华
Original assignee: Mass Technology HK Ltd
Current assignee: Mass Technology HK Ltd
Priority date: 1996-09-24
Filing date: 1996-09-24
Publication date: 1998-09-09
Anticipated expiration: 2016-09-24
Also published as: EP0831677A2; CN1113583C; EP0831677A3; AU1256397A; AU737784B2

Abstract

A kind of fluorescent lamp electronic ballast consists of commutating circuit, filter circuit, high frequency generating and controlling circuit, primary and secondary current following circuits which are connected between the commutating circuit and filter circuit, and are used for increasing the power factor of the ballast and restraining the interference of current harmonic wave. The input current is continuous and can be changed with inputted voltage, thus the power factor is increased and the rear stage high-frequency generating and controlling circuit is made work in stable state simultaneously because that primary and secondary current following circuits are led in. The interference of current harmonic wave of the ballast is restrained effectively, the pollution for electric network is reduced, the safety is raised.

Description

Electronic ballast for fluoresent lamp

The present invention relates to the operating circuit of fluorescent lamp, relate in particular to the electric ballast of fluorescent lamp.

Existing electronic ballast for fluoresent lamp all adopts AC-DC-exchange conversion, lights fluorescent lamp by the high frequency electric source that civil power is transformed to tens of kilo hertzs.This electric ballast generally includes rectification circuit, filter circuit, high frequency generation and (see figure 1)s such as control circuit and 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 rectification circuit diode is very little, its current waveform is illustrated in figure 3 as 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, if use this kind ballasts in a large number in three-phase power line, the current in middle wire in the circuit is very big with making, to the potential harm of safety formation of electrical network.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 object of the present invention is to provide and a kind ofly have High Power Factor, can reduce Harmonic Interference, and can guarantee the electronic ballast for fluoresent lamp of Electrical Safety supply network.

To achieve these goals, electronic ballast for fluoresent lamp of the present invention comprises: in order to civil power is converted to galvanic rectification circuit and filter circuit, in order to described direct current is converted to high frequency electric source to fluorescent tube provide the high frequency generation of working power and control circuit, in order to start the tube starting circuit that fluorescent tube lights and be connected in rectification circuit and filter circuit between, in order to the power factor that improves ballast with suppress the major and minor freewheeling circuit that current harmonics disturbs.

According to electronic ballast for fluoresent lamp of the present invention, owing between rectification circuit and filter circuit, added major and minor freewheeling circuit, change thereby make input current be continuity and can follow input voltage, improved the power factor of ballast, made the high frequency generation and the control circuit of back level work in stable state simultaneously.And the current harmonics of ballast disturbs and is effectively suppressed, and has reduced the pollution to electrical network, has improved Electrical Safety.In addition, according to electronic ballast for fluoresent lamp of the present invention,, can make the radio frequency conducted interference of ballast meet the standard that International Electrotechnical Commission (IEC) formulates owing to adopted major and minor freewheeling circuit.

Below with reference to drawings and Examples electronic ballast for fluoresent lamp of the present invention is described in further detail, other purpose of the present invention, characteristics and advantage will become clearer in the following description.

Fig. 1 is the electrical schematic diagram of the electronic ballast for fluoresent lamp of prior art;

Fig. 2 is the sketch of rectification circuit and filter circuit in the electronic ballast for fluoresent lamp shown in Figure 1;

Fig. 3 is the input current waveform of the electronic ballast for fluoresent lamp of prior art;

Fig. 4 is the block diagram of expression electronic ballast for fluoresent lamp according to an embodiment of the invention;

Fig. 5 is the electrical schematic diagram of expression electronic ballast for fluoresent lamp according to an embodiment of the invention;

Fig. 6 is the current/voltage oscillogram of electronic ballast for fluoresent lamp shown in Figure 5;

Fig. 7 is the radio frequency conducted interference figure of electronic ballast for fluoresent lamp shown in Figure 5.

Referring to Fig. 4 and Fig. 5, Fig. 4 and Fig. 5 represent the block diagram and the electrical schematic diagram of electronic ballast for fluoresent lamp according to an embodiment of the invention respectively.This electronic ballast for fluoresent lamp comprises that rectification circuit 11, secondary freewheeling circuit 13, main freewheeling circuit 14, filter circuit 16, high frequency take place and control circuit 17 and tube starting circuit 18.Wherein, rectification circuit 11, filter circuit 16, high frequency generation and control circuit 17 and tube starting circuit 18 for example adopt the circuit of prior art, and it can constitute as follows.That is, rectification circuit 11 comprises the bridge rectifier of being made up of diode D1 to D4.Filter circuit 16 comprises electrochemical capacitor C.High frequency takes place and control circuit 17 comprises triode BG1, BG2, diode D6 to D9, and resistance R 1 is to R6, and capacitor C 4 is to C6, and inductance L 3 is to L6.Wherein, diode D6 and D7 are connected in parallel in the two ends of electrochemical capacitor C, promptly between point of the F among the figure and the ground end; Capacitor C 4 is connected between the node (G point) that the F point is connected with diode D6 and D7; The collector electrode of triode BG1 is connected to the F point, and emitter is connected to the G point, and base stage then is connected to the F point via resistance R 3, and is connected to the G point via the resistance R 5 that is connected in series and diode D9 and the resistance R 1 that is connected in series, capacitor C 5 and inductance L 5 respectively; The collector electrode of triode BG2 is connected to the G point, and emitter is held with being connected to, and base stage then is connected to the G point via resistance R 4, and holds via the resistance R 6 that is connected in series and diode D8 and the resistance R 2 that is connected in series, capacitor C 6 and inductance L 6 respectively with being connected to; Inductance L 3 and L4 are connected in series between the pin of G point and fluorescent tube Y.Tube starting circuit 18 comprises the capacitor C 7 of cross-over connection between fluorescent tube Y two pins.

As previously mentioned, characteristics of the present invention are to have introduced major and minor freewheeling circuit between rectification circuit 11 and filter circuit 16.Wherein, secondary freewheeling circuit 13 comprises inductance L 1 and the capacitor C 1 that is connected in series, and two terminal A point and D point (promptly holding) cross-over connection are in the output of rectification circuit 11.Main freewheeling circuit 14 comprises that (its inductance value is selected≤10 milihenries to inductance L 2,5 milihenries for example), (its capacitance is selected≤0.1 microfarad for capacitor C 2, C3,0.01 microfarad for example, withstand voltage 〉=400 volt) and diode D5 (for example select withstand voltage 〉=400 volt FR104 type fast recovery diode).One end of inductance L 2 is connected to the node (B point) that inductance L 1 is connected with capacitor C 1, and the other end is connected with the positive pole of diode D5; The negative pole of diode D5 is connected to the F point; Capacitor C 2 and C3 are connected in series between the node (C point) and ground end that inductance L 2 is connected with diode D5, and the node (E point) that is connected with C3 of capacitor C 2 is connected to another pin of fluorescent tube Y.

The adding of above-mentioned major and minor freewheeling circuit makes the angle of flow of rectification circuit 11 diode D1 to D4 increase, thereby makes the input current waveform of ballast be trended towards approaching sinusoidal waveform as shown in Figure 6 continuously by original discontinuous spike.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.Electronic ballast for fluoresent lamp according to the above embodiment of the present invention, its power factor can be up to 0.95-1, and its electric current total harmonic distortion THD is about 10%.

Table one has been listed the multiple harmonic percentage of this ballast.

Table one

K01：100.00％ K20：000.63％

K02：002.00％ K21：000.37％K03：008.94％ K22：001.63％K04：001.30％ K23：000.32％K05：004.84％ K24：001.23％K06：000.75％ K25：001.80％K07：002.85％ K26：000.35％K08：000.48％ K27：000.60％K09：001.52％ K28：000.96％K10：000.50％ K29：000.26％K11：001.94％ K30：000.86％K12：001.52％ K31：001.05％K13：000.69％ K32：000.49％K14：001.05％ K33：001.20％K15：001.69％ K34：000.50％K16：001.43％ K35：001.63％K17：000.23％ K36：000.88％K18：001.63％ K37：001.52％K19：002.27％ K38：000.73％K39：001.04％THD：012.72％

Referring to Fig. 7, it shows the radio frequency conducted interference figure of electronic ballast for fluoresent lamp of the present invention, and as can be seen from the figure it has reached the standard that International Electrotechnical Commission (IEC) formulates.

Certainly, the above only is a preferred embodiment of the present invention, according to above-mentioned design of the present invention, those skilled in the art also can make many variations and conversion to this, for example, also major and minor freewheeling circuit of the present invention can be inserted between the rectification circuit and high frequency generation and control circuit of ballast; In addition, major and minor freewheeling circuit of the present invention also can apply in other various electric ballasts commonly used, but suchlike conversion all belongs to scope of the present invention.

Claims

1. electronic ballast for fluoresent lamp, comprise: in order to civil power be converted to galvanic rectification circuit 11 and filter circuit 16, provide the high frequency of working power to take place and control circuit 17 and to fluorescent tube in order to start the tube starting circuit 18 that fluorescent tube is lighted in order to described direct current is converted to high frequency electric source, it is characterized in that, described electric ballast also comprise be connected between rectification circuit 11 and the filter circuit 16, in order to the power factor that improves ballast with suppress main freewheeling circuit 14 and the secondary freewheeling circuit 13 that current harmonics disturbs.

2. electronic ballast for fluoresent lamp as claimed in claim 1 is characterized in that, secondary freewheeling circuit 13 comprises inductance L 1 and the capacitor C 1 that is connected in series, and its two ends cross-over connection is in the output of rectification circuit 11.

3. electronic ballast for fluoresent lamp as claimed in claim 2 is characterized in that, main freewheeling circuit 14 comprises inductance L 2, capacitor C 2, C3 and diode D5, wherein, an end of inductance L 2 is connected to the node that inductance L 1 is connected with capacitor C 1, and the other end is connected with the positive pole of diode D5; The negative pole of diode D5 is connected to high frequency and takes place and control circuit 17; Capacitor C 2 and C3 are connected in series between the node and ground end that inductance L 2 is connected with diode D5, and the node that is connected with C3 of capacitor C 2 is connected to the pin of fluorescent tube Y.

4. electronic ballast for fluoresent lamp as claimed in claim 3 is characterized in that, inductance L 2 is selected inductance value≤10 milihenries; Capacitor C 2, C3 select capacitance≤0.1 microfarad, withstand voltage 〉=400 volt; Diode D5 selects withstand voltage 〉=400 volt.

5. electronic ballast for fluoresent lamp as claimed in claim 4 is characterized in that, described diode D5 is a fast recovery diode.