CN2770272Y - Light modulating electronic ballast - Google Patents

Abstract

The utility model relates to a dimming type electron ballast, which is used for a high-intensity discharge lamp. The electron ballast comprises a gas discharge lamp main loop and a control circuit, wherein the gas discharge lamp main loop is connected with the high-intensity discharge lamp, and the control circuit is connected with the gas discharge lamp main loop; the gas discharge lamp main loop is composed of a low-pass filtering rectifying circuit, a power factor correcting circuit, a bridge type inverted circuit and a T type filter resonance circuit; besides, the control circuit is composed of a dimming signal sampling circuit, a frequency modulation circuit, an isolating driving circuit, a starting control circuit and a starting circuit.

Description

A dimming electronic ballast

Technical field

The utility model belongs to the technical field of applied electronics and relates to a ballast, in particular to a light-adjustable electronic ballast for high-intensity gas discharge lamps.

Background technique

High-intensity discharge lamps (HID) mainly include metal halide lamps (MHL), high-pressure sodium lamps (HPS), high-pressure mercury lamps, and some special gas discharge lamps such as xenon lamps and krypton lamps. HID lamps have the advantages of small size, high luminous efficiency, good color rendering, and long life, and have become the third generation of electric light sources after incandescent lamps and fluorescent lamps. Electronic ballasts have the advantages of high power factor, high efficiency, small size, light weight, no noise, no flicker, etc., and will gradually replace traditional inductive ballasts. However, for high-intensity gas discharge lamps, especially metal halide lamps, the problem of acoustic resonance exists in the high-frequency working mode.

At present, the relatively mature and reliable low-frequency square wave lighting electronic ballast is characterized by reducing the operating frequency of the inverter stage to below the lower limit frequency of acoustic resonance, which is tens to hundreds of Hz, and can achieve the purpose of silent resonance. Since low-frequency square wave lighting electronic ballasts often use three-stage circuits, and the bridge inverter circuit of the inverter stage is a full-bridge inverter circuit, the cost is high, the volume is large, and low-frequency noise is likely to occur.

Contents of Invention

The purpose of the utility model is to provide a silent resonant ultra-high frequency electronic ballast based on a T-shaped filter for a high-intensity gas discharge lamp.

The purpose of this utility model is to be accomplished through the following technical solutions:

The resonant circuit in the commonly used resonant inverter stage generally adopts a series resonant circuit (SLR) or a parallel resonant circuit (PLR). However, the series resonant circuit and parallel resonant circuit must be used to achieve deep dimming, and the operating frequency of the inverter stage varies widely, which brings difficulties to the design of the EMI filter. At the same time, the series resonant circuit and parallel resonant circuit are adopted, and the crest factor of the lamp current is relatively high, and an excessively high crest factor of the lamp current will greatly reduce the service life of the lamp. At the same time, the resonant ignition method cannot be used with the series resonant circuit, and only the additional ignition method can be used, that is, the bridge inverter circuit, the resonant circuit, the starting circuit, and the starting control circuit are not multiplexed, the structure is complex, and the cost is high; the parallel resonant circuit cannot be used. With the additional ignition method, only the resonant ignition method can be used, that is, the bridge inverter circuit, the resonant circuit, the starting circuit, and the starting control circuit are multiplexed, that is, the starting circuit and the starting control circuit are omitted, and it is difficult to realize the hot start function.

If the resonant circuit in the resonant inverter stage adopts a T-shaped filter resonant circuit, deep dimming can be realized within a narrow operating frequency range of the inverter stage. At the same time, the T-type filter resonant circuit is adopted, the lamp current is close to a sine wave, and the current crest factor is low, thereby prolonging the life of the lamp. Moreover, the resonant ignition mode and the additional ignition mode can be adopted by using the T-shaped filter resonant circuit, which can be considered comprehensively according to the actual situation.

Therefore, the designed electronic ballast for dimming high-intensity gas discharge lamps includes: the main circuit of the gas discharge lamp connected with the high-intensity gas discharge lamp, and the control circuit connected with the main circuit of the gas discharge lamp. The main circuit of the gas discharge lamp is composed of a low-pass filter rectifier circuit, a power factor correction circuit, a bridge inverter circuit, and a T-type filter resonant circuit; the control circuit is a dimming signal sampling circuit, a frequency modulation circuit, an isolation drive circuit, Composed of start-up control circuit and start-up circuit; low-pass filter rectifier circuit, power factor correction circuit, bridge inverter circuit, T-type filter resonant circuit, sequentially connected between power frequency AC mains and high-intensity gas discharge lamp; The dimming signal sampling circuit is connected to the frequency modulation circuit, the power factor correction circuit is connected to the frequency modulation circuit, the frequency modulation circuit is connected to the isolation drive circuit, and the isolation drive circuit is connected to the bridge inverter circuit; the power factor correction circuit is connected to the startup circuit, and the startup circuit is connected to the high-intensity The gas discharge lamp; after the high-intensity gas discharge lamp is connected to the starting control circuit, the starting control circuit is connected to the starting circuit.

Compared with inductive ballasts, another advantage of electronic ballasts is that they can easily realize the dimming function. Commonly used resonant high-frequency electronic ballasts are generally composed of a power factor correction stage and a resonant inverter stage. The power factor correction stage is composed of a low-pass filter rectifier circuit and a power factor correction circuit. The resonant inverter stage is composed of a bridge inverter. circuit, resonant circuit and control circuit. In order to realize the dimming function, some solutions are proposed as follows.

The voltage regulation and dimming method refers to adjusting the input DC voltage of the resonant inverter stage, that is, the output DC voltage of the power factor correction stage to change the lamp power output. The advantage of this method is that the operating frequency of the inverter stage is fixed, and it can maintain the zero voltage switching (ZVS) working condition of the bridge inverter circuit in a wide dimming range. However, this method puts forward higher requirements on the topology of the power factor correction stage, and the output DC voltage adjustment range of the commonly used power factor correction stage is limited, which can only meet the mild dimming requirements.

The duty ratio dimming method generally uses a full-bridge inverter circuit, which is relatively complicated and expensive. It can also be implemented with a half-bridge inverter circuit. The switch tube works symmetrically, and its duty ratio is adjusted to make the inductor current enter an intermittent working state to realize dimming. However, due to the high crest factor of the current, it is not suitable for use. It is generally believed that the lamp current crest factor should be controlled within 1.7.

In the frequency modulation and dimming method, the resonant inverter stage generally works above the natural resonant frequency of the resonant circuit, and the load of the bridge inverter circuit is generally inductive. The frequency modulation dimming method refers to adjusting the operating frequency of the resonant inverter stage to change the lamp power output. This is the easiest and most commonly used dimming method.

Compared with the existing technology: the characteristic of this design is that the operating frequency of the inverter stage is increased above the upper limit frequency of acoustic resonance, which is hundreds of kilohertz to several megahertz, and the purpose of silent resonance can be achieved. At the same time, due to the high operating frequency of the inverter stage, the resonant circuit inductor and capacitor are reduced in volume and cost. Since the ultra-high frequency lighting electronic ballast adopts a secondary circuit, and the bridge inverter circuit of the inverter stage can adopt a half-bridge inverter circuit, the cost is low, the volume is small, and audio noise can be avoided.

Description of drawings

Figure 1 is a schematic block diagram of an electronic ballast for dimming high-intensity gas discharge lamps.

FIG. 2 is a schematic diagram of a half-bridge inverter circuit of the bridge inverter circuit in FIG. 1 .

FIG. 3 is a schematic diagram of a half-bridge inverter circuit of another bridge inverter circuit in FIG. 1 .

FIG. 4 is a schematic diagram of a half-bridge inverter circuit of another bridge inverter circuit in FIG. 1 .

FIG. 5 is a schematic diagram of a full-bridge inverter circuit of the bridge inverter circuit in FIG. 1 .

FIG. 6 is a schematic diagram of the resonant circuit of the T-shaped filter in FIG. 1 .

FIG. 7 is a schematic diagram of the startup circuit in FIG. 1 .

Detailed ways

The design will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

Embodiment 1: The dimming electronic ballast for high-intensity gas discharge lamps includes a gas discharge lamp main circuit 12 connected to the high-intensity gas discharge lamp 2 and a control circuit 13 connected to the gas discharge lamp main circuit. The main circuit of the gas discharge lamp is composed of a low-pass filter rectifier circuit 3, a power factor correction circuit 4, a bridge inverter circuit 5, and a T-type filter resonant circuit 6; the control circuit is a dimming signal sampling circuit 9 , frequency modulation circuit 10, isolation drive circuit 7, start control circuit 11, start circuit 8; described low-pass filter rectifier circuit 3, power factor correction circuit 4, bridge inverter circuit 5, T-type filter resonance The circuit 6 is sequentially connected between the power frequency AC mains 1 and the high-intensity gas discharge lamp 2; the dimming signal sampling circuit 9 is connected to the frequency modulation circuit 10, and the power factor correction circuit 4 is connected to the frequency modulation circuit 10, and the frequency modulation The circuit 10 is connected to the isolated drive circuit 7, and the isolated drive circuit 7 is connected to the bridge inverter circuit 5; the power factor correction circuit 4 is connected to the starting circuit 8, and the starting circuit 8 is connected to the high-intensity gas discharge lamp 2; the high-intensity gas After the discharge lamp 2 is connected to the start control circuit 11 , the start control circuit 11 is connected to the start circuit 8 .

Wherein the bridge inverter circuit 5 is a half-bridge inverter circuit: it is composed of switch tubes Q11, Q12, and capacitor C11; the output terminals of the switch tubes Q11 and Q12 are connected in series, and the mid-terminal connection capacitor C11 is connected in series with the output terminals of the switch tubes Q11 and Q12. One end, the two terminals connected in series with the output terminals of the switching tubes Q11 and Q12 are the input terminals, and the other terminal of the capacitor C11 and the output terminals of the switching tubes Q11 and Q12 connected in series are the output terminals.

Among them, the T-shaped filter resonant circuit 6 is composed of inductors L1, L2, and capacitor C; one end of capacitor C is connected to one end of inductor L1 and one end of inductor L2, the other end of inductor L1 and the other end of capacitor C are input ends, and inductor L2 The other end, the other end of the capacitor C is the output end.

The starting circuit 8 is composed of a resistor R, a capacitor C1, a transformer T, and a switch tube Q. One end of the primary side of the transformer T is connected to one end of the resistor R and one end of the capacitor C1, and the other end of the primary side of the transformer T is connected to one end of the output end of the switch tube Q. The other end of the output end of the tube Q is connected to the other end of the capacitor C1, and the other end of the resistor R is the input end, and the two ends of the secondary side of the transformer T are the output ends.

The output current sampling point of the power factor correction circuit 4 is connected to the input terminal of the frequency modulation circuit 10, the output terminal of the dimming signal sampling circuit 9 is connected to the other input terminal of the frequency modulation circuit 10, and the output terminal of the frequency modulation signal circuit 10 is connected to the input terminal of the isolation drive circuit 7 , the output end of the isolation drive circuit 7 is connected to the control input ends of each switching tube of the bridge inverter circuit 5 .

Specific embodiment 2: the electronic ballast for dimming high-intensity gas discharge lamps described in embodiment 1, wherein the bridge inverter circuit 5 adopts: composed of switch tubes Q21, Q22, capacitors C21, C22; switch tube Q21 is connected in series with the output terminals of the switching tube Q22; the capacitor C21 is connected in series with the capacitor C22; C21, C22 are connected in series with two terminals connected in parallel, and the two terminals connected in parallel are used as input terminals; the middle terminal connected in series with the output terminals of the switch tubes Q21 and Q22 and the middle terminal connected in series with capacitors C21 and C22 are used as the output terminal half-bridge inverter circuit.

Specific embodiment 3: the electronic ballast for the dimming type high-intensity gas discharge lamp described in embodiment 1, wherein the bridge inverter circuit 5 adopts a full bridge inverter circuit: the switch tubes Q31, Q32, Q33, Q34 constitutes; the output ends of the switch tubes Q31 and Q32 are connected in series; the output tubes of the switch tubes Q33 and Q34 are connected in series; The two terminals connected in series at the output end of Q32 and the two terminals connected in series with the output terminals of the switch tubes Q33 and Q34 in parallel are input terminals, the middle end of the series connection of the output ends of the above-mentioned switch tubes Q31 and Q32, and the middle end of the series connection of the output ends of the switch tubes Q33 and Q34 are output.

Specific embodiment 4: the electronic ballast for the dimming type high-intensity gas discharge lamp described in embodiment 1, wherein the output end of the power factor correction circuit 4 is connected to the input end of the starting circuit 8, and the current sampling point of the high-intensity gas discharge lamp 2 The input end of the start control circuit 11 is connected, the output end of the start control circuit 11 is connected to the control input end of the switching tube Q of the start circuit 8, and the output end of the start circuit 8 is connected to the high-intensity gas discharge lamp 2 in series.

Specific embodiment 5: the electronic ballast for dimming type high-intensity gas discharge lamp described in embodiment 1, wherein the output end of the power factor correction circuit 4 is connected to the input end of the starting circuit 8, and the current sampling point of the high-intensity gas discharge lamp 2 Connect the input end of the start control circuit 11, the output end of the start control circuit 11 is connected to the control input end of the switch tube Q of the start circuit 8, the secondary side of the transformer T of the start circuit 8 is multiplexed with the inductor L2 of the T-type filter resonant circuit 6, that is, the secondary side of the transformer T Side is the inductor L2.

Specific embodiment 6: the electronic ballast for dimming type high-intensity gas discharge lamps described in embodiment 1, wherein the bridge inverter circuit 5, the T-type filter resonant circuit 6, the starting circuit 8, and the starting control circuit 11 Multiplexing means omitting the startup circuit 8 and the startup control circuit 11 .

Claims (10)

1. An electronic ballast for a dimming type high-intensity gas discharge lamp, comprising a gas discharge lamp main circuit (12) connected to a high-intensity gas discharge lamp (2), and a control circuit connected to a gas discharge lamp main circuit ( 13), characterized in that: the main circuit of the gas discharge lamp is composed of a low-pass filter rectifier circuit (3), a power factor correction circuit (4), a bridge inverter circuit (5), a T-type filter resonant circuit ( 6) composed of; the control circuit is composed of dimming signal sampling circuit (9), frequency modulation circuit (10), isolation drive circuit (7), start control circuit (11), and start circuit (8); the The low-pass filter rectifier circuit (3), power factor correction circuit (4), bridge inverter circuit (5), T-type filter resonant circuit (6), in the industrial frequency AC mains (1) and high-intensity The gas discharge lamps (2) are sequentially connected; the dimming signal sampling circuit (9) is connected to the frequency modulation circuit (10), the power factor correction circuit (4) is connected to the frequency modulation circuit (10), and the frequency modulation circuit (10) is connected to the frequency modulation circuit (10). ) is connected to the isolated driving circuit (7), and the isolated driving circuit (7) is connected to the bridge inverter circuit (5); the power factor correction circuit (4) is connected to the starting circuit (8), and the starting circuit (8) is connected to the high-intensity A gas discharge lamp (2); after the high-intensity gas discharge lamp (2) is connected to the start control circuit (11), the start control circuit (11) is connected to the start circuit (8). 2. The electronic ballast for dimming high-intensity gas discharge lamps according to claim 1, characterized in that: the bridge inverter circuit (5) is a half-bridge inverter circuit: the switching tube ( Q11, Q12) and capacitor (C11); the output terminals of the switch tubes (Q11, Q12) are connected in series, and the middle end of the output terminals of the switch tubes (Q11, Q12) connected in series is connected to one end of the capacitor (C11), and the switch tubes (Q11, Q12) are connected in series. The two terminals connected in series with the output terminals of Q12 are the input terminals, and any one of the two terminals connected in series with the other terminal of the capacitor (C11) and the output terminals of the switch tubes (Q11, Q12) is the output terminal. 3. The electronic ballast for dimming type high-intensity gas discharge lamps according to claim 1, characterized in that: the bridge inverter circuit (5) is a half-bridge inverter circuit: the switching tube ( Q21, Q22), capacitors (C21, C22); the above-mentioned switching tube (Q21) and the output terminal of the switching tube (Q22) are connected in series; the above-mentioned capacitor (C21) and the capacitor (C22) are connected in series; the above-mentioned switching tube (Q21, Q22) output two terminals connected in series with capacitors (C21, C22) and two terminals connected in parallel; the output terminals of the switch tubes (Q21, Q22) connected in series with two terminals connected in series with capacitors (C21, C22) in parallel, and the two terminals connected in parallel with capacitors (C21, C22) are input terminals; (Q21, Q22) the middle terminal connected in series with the output terminals and the middle terminal connected in series with the capacitors (C21, C22) are the output terminals. 4. The electronic ballast for dimming high-intensity gas discharge lamps according to claim 1, characterized in that: the bridge inverter circuit (5) is a full bridge inverter circuit: the switching tube ( Q31, Q32, Q33, Q34) form; the output terminals of the above switching tubes (Q31, Q32) are connected in series, the output tubes of the switching tubes (Q33, Q34) are connected in series, and the output terminals of the switching tubes (Q31, Q32) are connected in series with the switching tube (Q33) ), the output terminals of the switch tube (Q34) are connected in series and two terminals are connected in parallel, and the output terminals of the above switch tubes (Q31, Q32) are connected in series and two terminals are connected in series with the output terminals of the switch tube (Q33) and the switch tube (Q34). terminal, the mid-terminal connected in series with the output terminals of the switching tubes (Q31, Q32) and the mid-terminal connected in series with the output terminals of the switching tubes (Q33, Q34) are the output terminals. 5. The electronic ballast for dimming type high-intensity gas discharge lamps according to claim 1, characterized in that: the T-shaped filter resonant circuit (6) is composed of inductors (L1, L2), capacitors ( C) Composition; one end of the above-mentioned capacitor (C) is connected to one end of the inductor (L1) and one end of the inductor (L2), the other end of the above-mentioned inductor (L1) and the other end of the capacitor (C) are input terminals, and the above-mentioned inductor (L2) The other end, the other end of the capacitor (C) is the output end. 6. The electronic ballast for dimming type high-intensity gas discharge lamps according to claim 1, characterized in that: the starting circuit (8) is composed of a resistor (R), a capacitor (C1), a transformer (T ), a switch tube (Q), one end of the primary side of the transformer (T) is connected to one end of the resistor (R) and one end of the capacitor (C1), the other end of the primary side of the transformer (T) is connected to the output end of the switch tube (Q), and the switch tube (Q) The other end of the output end is connected to the other end of the capacitor (C1), and the other end of the resistor (R) is the input end, and the two ends of the secondary side of the transformer (T) are the output ends. 7. The electronic ballast for dimming high-intensity gas discharge lamps according to claim 1, characterized in that: the output current sampling point of the power factor correction circuit (4) is connected to the input terminal of the frequency modulation circuit (10) , the output end of the dimming signal sampling circuit (9) is connected to the other input end of the frequency modulation circuit (10), the output end of the frequency modulation signal circuit (10) is connected to the input end of the isolation drive circuit (7), and the output end of the isolation drive circuit (7) Connect the control input terminals of each switching tube of the bridge inverter circuit (5). 8. The electronic ballast for dimming type high-intensity gas discharge lamps according to claim 1, characterized in that: the output end of the power factor correction circuit (4) is connected to the input end of the starting circuit (8), and the high-intensity The current sampling point of the gas discharge lamp (2) is connected to the input end of the start control circuit (11), the output end of the start control circuit (11) is connected to the control input end of the start circuit (8) switch tube (Q), and the output end of the start circuit (8) is connected in series Connect the high-intensity discharge lamp (2). 9. The dimming-type electronic ballast for high-intensity gas discharge lamps according to claim 1, characterized in that: the output end of the power factor correction circuit (4) is connected to the input end of the starting circuit (8), and the high-intensity The current sampling point of the gas discharge lamp (2) is connected to the input end of the start control circuit (11), the output end of the start control circuit (11) is connected to the control input end of the start circuit (8) switch tube (Q), and the start circuit (8) transformer (T ) secondary side and T-shaped filter resonant circuit (6) inductor (L2) multiplexing, that is, the secondary side of the transformer (T) is the inductor (L2). 10. The electronic ballast for dimming type high-intensity gas discharge lamps according to claim 1, characterized in that: the bridge inverter circuit (5), the T-type filter resonant circuit (6) and the starting The circuit (8) and the start control circuit (11) are multiplexed, that is, the start circuit (8) and the start control circuit (11) are omitted.

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