CN201418195Y

CN201418195Y - Low voltage electronic ballast

Info

Publication number: CN201418195Y
Application number: CN2009201601185U
Authority: CN
Inventors: 杨建华
Original assignee: Individual
Current assignee: Individual
Priority date: 2009-06-18
Filing date: 2009-06-18
Publication date: 2010-03-03
Anticipated expiration: 2019-06-18

Abstract

The utility model discloses a low voltage electronic ballast, comprising a pulse width modulation circuit (PWM), a voltage type push-pull circuit, and a LC resonant ignition circuit, wherein a secondary side of a push-pull transformer of the voltage type push-pull circuit is provided with a photoelectric coupling circuit, which collects instable high frequency voltage signals of the secondary sideof the push-pull transformer and controls and regulates a pulse output width of the PWM circuit according to the signals, such that the voltage type push-pull circuit outputs a stable high frequencyvoltage. According to the utility model, it is possible to regulate output power and make the lamp light to be constant; the utility model is suitable for modes of width modulation, frequency modulation, etc., and constant light output circuits of various high/low-voltage, AC/DC ballast; the constant light output circuit has a simple structure, low cost, high reliability, and high efficiency; andit is possible to prolong the service lifetime of the tube and provide an effective solving scheme for constant light output of the electronic ballast.

Description

The Low-voltage Electronic ballast

Technical field

The utility model relates to a kind of circuit that goes for transferring the permanent light output of ballast of modes such as wide, frequency modulation, particularly a kind of ballast that utilizes the permanent lamp power of photoelectrical coupler.

Background technology

Along with the popularization of green illumination, the fluorescent lamp and the electric ballast thereof of efficient energy-saving are used on a large scale.The high-performance electronic ballast of existing AC power (AC) input, comprise Europe superscript, U.S. mark, most of employing Active Power Factor Correction (APFC) is carried out circuit and is boosted, to obtain High Power Factor, obtain stable ballast direct-current working volts (DC) simultaneously, supply with half-bridge inverter, light a lamp through the permanent power of LC resonance.Yet for the fluorescent lamp of low-voltage power supply, as: the storage battery power supply, especially solar panels charge to storage battery, the electric energy that obtains is then more unstable, for example, and when battery voltage raises 10% the time, for the Low-voltage Electronic ballast of push-pull circuit, the lamp power of output will increase by 20%.The instability of power output will directly cause following harm: the lamp tube service life of fluorescent lamp is significantly reduced; 2, ballast self energy consumption increases; 3, the electric energy of waste storage battery, neither environmental protection can cause the inconvenience in the use again; 4, for guaranteeing the reliability of ballast, must increase the thermal capacity of ballast, thereby cause product cost to increase.

For separating above-mentioned harm, need a kind of design that makes the permanent power of Low-voltage Electronic ballast in the industry, make light output stable.Yet, electric ballast for the low pressure input, because input current is greater than exchanging tens of times of (AC) electric ballasts, use that interchange (AC) input electric ballast APFC circuit-mode designs can permanent power output the Low-voltage Electronic ballast not only the ballast efficiency is very low, and circuit complexity, loss are serious, especially the very high solar energy-electric energy of corresponding cost, very important especially, therefore be difficult to commercialization and use.

As seen prior art has the Low-voltage Electronic ballast circuit complexity of permanent power, can not realize effects such as low cost, highly reliable, high energy efficiency, therefore, have light constant a kind of low energy consumption of high-quality low-pressure type electric ballast needs, the practicable circuit arrangement that can be used for commercialization of cost.

The utility model content

In view of this, the purpose of this utility model is to provide a kind of Low-voltage Electronic ballast, so that it under the prerequisite that does not increase the ballast excess loss, obtains stable power output and luminous flux, makes light constant.

For achieving the above object, the invention provides following scheme:

A kind of Low-voltage Electronic ballast, comprise pulse width modulation circuit (PWM), voltage-type push-pull circuit, LC resonance point circuit for lamp, push-pull transformer secondary at described voltage-type push-pull circuit is provided with the photoelectricity coupling circuit, this photoelectricity coupling circuit is gathered the unsettled high-frequency voltage signal of this push-pull transformer secondary and is changed the width of pulse output with this signal controlling regulating impulse width modulation circuit (PWM), make the voltage-type push-pull circuit export a stable high frequency voltage, this stable high frequency voltage is exported to LC resonance point circuit for lamp.

Aforesaid Low-voltage Electronic ballast, described photoelectricity coupling circuit comprises luminous tube, transistor, the collection of photoelectricity coupling circuit is owing to the instability of low-tension supply power supply causes the unsettled high-frequency voltage signal of described push-pull transformer secondary, and the variable signal that unsettled high frequency voltage variable quantity is converted to the luminous tube light of photoelectricity coupling circuit is passed to photoelectricity coupling circuit transistor one end, utilize its impedance variation control impuls width modulation circuit (PWM) that pulse duration is changed.

Aforesaid Low-voltage Electronic ballast; it also comprises the abnormal condition of lamp tube protective circuit; when this abnormal condition of lamp tube protective circuit does not activate or rectifier phenomena occurs and cause the field effect transistor overcurrent at fluorescent tube; overcurrent signal is delivered to pulse width modulation circuit (PWM) protection end, turn-offs driving pulse with the protection field effect transistor.

Aforesaid Low-voltage Electronic ballast, it also comprises the current rectifying and wave filtering circuit that is used for rectification full-bridge when ac power supply.

Aforesaid Low-voltage Electronic ballast, described photoelectricity coupling circuit is a precision photoelectric coupler.

Aforesaid Low-voltage Electronic ballast, described photoelectricity coupling circuit carries out dividing potential drop by resistance (R11, R12) to the high frequency voltage that push-pull transformer (T1) secondary changes, and the variation of photoelectricity coupling circuit (Q4) luminous tube side electric current is coupled to its transistor side, when photoelectricity coupling circuit (Q4) luminous tube electric current is changed, its transistor conduct resistance changes thereupon, and makes push-pull transformer electric current power output produce respective change by pulse width modulation circuit (PWM).

According to the specific embodiment that the utility model provides, following technique effect is disclosed:

Low-voltage Electronic ballast of the present utility model is based on pulse width modulation generator (PWM) and drives and to design on the push-pull circuit basis, at push-pull transformer secondary sampling high frequency voltage variable quantity, isolate via photoelectricity, change the width of (PWM) generator driving pulse, thereby the adjusting power output makes light constant.The utility model is applicable to modes such as transferring wide, frequency modulation simultaneously, and the permanent light output circuit of the multiple ballast of various high-low pressure, alternating current-direct current, and circuit structure is simple, low-cost, highly reliable, high energy efficiency, and effective prolonging lamp tube service life.

Description of drawings

Further specify the utility model with reference to represented in the accompanying drawings non-limiting example below, wherein:

Fig. 1 is the block diagram of the Low-voltage Electronic ballast that provides of the utility model embodiment;

Fig. 2 is the circuit theory diagrams of the Low-voltage Electronic ballast that provides of the utility model embodiment.

Symbol description:

1, pulse width modulation circuit 2, voltage-type push-pull circuit

31, photoelectricity coupling circuit luminous tube side 32, photoelectricity coupling circuit transistor side

4, rectification circuit 5, LC resonance point circuit for lamp

6, abnormal condition of lamp tube protective circuit

Embodiment

For above-mentioned purpose of the present utility model, feature and advantage can be become apparent more, the utility model is described in further detail below in conjunction with the drawings and specific embodiments.

The utility model discloses a kind of circuit of electronic ballast that makes constant low-pressure type AC power (AC) of fluorescent tube light output or DC power supply (DC) input, the classical Low-voltage Electronic ballast that it is made up of current rectifying and wave filtering circuit, pulse width modulation circuit (PWM), voltage-type push-pull circuit, LC resonance point circuit for lamp, integrated photoelectricity coupling circuit, utilize this photoelectricity coupling circuit control impuls width modulation circuit (PWM) pulse duration to change, make push-pull circuit be output as a stable high frequency voltage, stablize the light output of fluorescent lamp.The circuit of the permanent power output of multiple ballast of modes such as that the utility model platform goes for transferring is wide, frequency modulation obtains the light stable flux under the prerequisite that does not increase the ballast excess loss.

See also shown in the accompanying drawing, Fig. 1 is the block diagram of the Low-voltage Electronic ballast that provides of the utility model embodiment, and Fig. 2 is the circuit theory diagrams of the Low-voltage Electronic ballast that provides of the utility model embodiment.The Low-voltage Electronic ballast that the utility model embodiment provides comprises pulse width modulation circuit (PWM), voltage-type push-pull circuit, LC resonance point circuit for lamp, reaches the photoelectricity coupling circuit.The chip U1 model that is adopted in the utility model accompanying drawing is SG3525A, but the utility model is not limited to this, all with circuit, the chip of its similar functions, structure, all within this patent protection range.

Pulse width modulation circuit (PWM) produces one group of positive negative pulse stuffing that differs 180 °, and is provided with pulse duration adjustment input, and the shutoff pulse ends that is used to protect.Driving pulse 14 pin of the chip U1 of pulse width modulation circuit (PWM) drive field effect transistor (VDMS) Q1 through resistance R 9, and driving pulse 11 pin drive field effect transistor (VDMS) Q2 through resistance R 10.

The voltage-type push-pull circuit comprises a pair of field-effect transistor (VDMS) Q1, Q2, and push-pull transformer T1, the field effect transistor Q1, the Q2 that link to each other by former limit are connected with pulse width modulation circuit (PWM), the former limit of push-pull transformer T1 is flow through and is controlled by Q1, the Q2 that pulse width modulation circuit drives, make it two windings of the high-frequency current of alternate conduction through the former limit of push-pull transformer T1, push-pull transformer T1 secondary output high-frequency high-voltage is to LC resonance point circuit for lamp.

Two primary current phase places of above-mentioned push-pull transformer T1 are opposite, secondary produces high frequency voltage, high frequency voltage connects capacitor C 9 through reactor L2 serially connected lamp tubes filament and forms resonance, capacitor C 9 two ends produce high voltage and light fluorescent tube, the tube impedance of being lighted reduces, the quality factor q value of LC resonance reduces, and reactor L2 ballast is for lamp works.

LC resonance point circuit for lamp includes inductance, electric capacity, is used to light fluorescent tube.

The photoelectricity coupling circuit, comprise luminous tube, transistor, be arranged on the push-pull transformer secondary of described voltage-type push-pull circuit, this photoelectricity coupling circuit changes according to the pulse duration of the unsettled high-frequency voltage signal regulating and controlling pulse width modulation circuit (PWM) of this push-pull transformer secondary output, make the voltage-type push-pull circuit export a stable high frequency voltage, promptly, high frequency voltage variable quantity with the generation of push-pull transformer secondary, deliver to regulating impulse width modulation circuit (PWM) through the photoelectricity isolation, adjust output pulse width and finish the photoelectricity isolation, constant light output.

Particularly, above-mentioned photoelectricity coupling circuit is that precision photoelectric coupler is advisable.The luminous tube side of above-mentioned photoelectricity coupling circuit is by resistance R 11, R12 carries out dividing potential drop to the high frequency voltage that push-pull transformer T1 secondary changes, and the instability of gathering owing to the low-tension supply power supply causes the unsettled high-frequency voltage signal of described push-pull transformer secondary, unsettled high frequency voltage variable quantity is converted to the variable signal of the luminous tube light of photoelectricity coupling circuit, be coupled to its transistor side by the variation of photoelectricity coupling circuit Q4 luminous tube side electric current, when photoelectricity coupling circuit Q4 luminous tube electric current is changed, its transistor conduct resistance changes thereupon, thereby the electric current variation is passed to photoelectricity coupling circuit transistor one end, utilize the pulse duration of its impedance variation control impuls width modulation circuit (PWM) to change, make push-pull transformer electric current power output produce respective change by pulse width modulation circuit (PWM) again.In this patent, the transistor internal resistance of photoelectrical coupler transistor side changes with the luminous tube electric current, the 9 pin current potentials of the chip U1 of pulse width modulation circuit (PWM) change, when supply voltage raises, transformer T1 secondary voltage raises, Q4 luminous tube side electrorheological is big, Q4 transistor side conducting resistance diminishes, the 9 pin current potential step-downs of chip U1, the field-effect transistor Q1 of voltage-type push-pull circuit, Q2 grid input pulse width narrows down, and the push-pull transformer current output pulse is narrowed down, thereby reduce the transformer power output, otherwise pulse broadens, and power of lamp tube obtains constant.

Ballast of the present utility model can also comprise the abnormal condition of lamp tube protective circuit; when this abnormal condition of lamp tube protective circuit does not activate or rectifier phenomena occurs and cause the field effect transistor overcurrent at fluorescent tube; overcurrent signal is delivered to pulse width modulation circuit (PWM) protection end; turn-off driving pulse with the protection field effect transistor, thereby prevent to cause field effect transistor (VDMS) overcurrent.Particularly; when abnormal condition of lamp tube does not activate; reactor L2 and capacitor C 9 resonance; make the push-pull transformer secondary current become big; be several times as much as the normal point lamp current; at this moment field effect transistor (VDMS) Q1; Q2 flows through respectively greater than normal operating current; as not cutting off field effect transistor (VDMS) Q1 immediately; the input grid impulse of Q2; then can burn immediately; so at field effect transistor Q1; the Q2 source electrode seals in the former limit of instrument transformer T2 winding; obtain overcurrent signal, be coupled to instrument transformer T2 secondary winding, obtain voltage signal with ratio through diode D6; resistance R 7; the gate leve of silicon controlled rectifier (SCR) Q3 is supplied with in R4 dividing potential drop and capacitor C 8 filtering; make it conducting; silicon controlled rectifier (SCR) Q3 anode is connected on chip U1 power end 15 pin, and chip U1 power supply is reduced to below the power supply threshold voltage, and chip U1 turn-offs; do not produce pulse signal; ballast is protected, more renew fluorescent tube after, operate as normal after the power-on.

Ballast of the present utility model is applicable to alternating current or powered by direct current, during direct current supply, be connected in series feeder ear 15 pin of the chip U1 of pulse width modulation circuit (PWM) with the parallel circuits of filter capacitor C5, C2, voltage-stabiliser tube D5 by resistance R 1, chip U1 is provided working power; When AC-powered, low-voltage AC is powered to main circuit by the full-bridge that rectifier diode D1, D2, D3, D4 form through fuse F1 overcurrent fuse F2, and direct current is back to low-voltage alternating current power supply via differential mode inductance L1.In addition, during AC-powered, ballast of the present utility model also comprises the current rectifying and wave filtering circuit that is used for rectification full-bridge when ac power supply.

More than Low-voltage Electronic ballast provided by the utility model is described in detail, used specific case herein principle of the present utility model and execution mode are set forth, the explanation of above embodiment just is used for helping to understand the utility model core concept; Simultaneously, for one of ordinary skill in the art, according to thought of the present utility model, part in specific embodiments and applications all can change.In sum, this description should not be construed as restriction of the present utility model.

Claims

1, a kind of Low-voltage Electronic ballast, comprise pulse width modulation circuit (PWM), voltage-type push-pull circuit, LC resonance point circuit for lamp, it is characterized in that, push-pull transformer secondary at described voltage-type push-pull circuit is provided with the photoelectricity coupling circuit, this photoelectricity coupling circuit is gathered the unsettled high-frequency voltage signal of this push-pull transformer secondary and is changed the width of pulse output with this signal controlling regulating impulse width modulation circuit (PWM), make the voltage-type push-pull circuit export a stable high frequency voltage, this stable high frequency voltage is exported to LC resonance point circuit for lamp.

2, Low-voltage Electronic ballast according to claim 1, it is characterized in that, described photoelectricity coupling circuit comprises luminous tube, transistor, the collection of photoelectricity coupling circuit is owing to the instability of low-tension supply power supply causes the unsettled high-frequency voltage signal of described push-pull transformer secondary, and the variable signal that unsettled high frequency voltage variable quantity is converted to the luminous tube light of photoelectricity coupling circuit is passed to photoelectricity coupling circuit transistor one end, utilize its impedance variation control impuls width modulation circuit (PWM) that pulse duration is changed.

3, Low-voltage Electronic ballast according to claim 1; it is characterized in that; it also comprises the abnormal condition of lamp tube protective circuit; when this abnormal condition of lamp tube protective circuit does not activate or rectifier phenomena occurs and cause the field effect transistor overcurrent at fluorescent tube; overcurrent signal is delivered to pulse width modulation circuit (PWM) protection end, turn-offs driving pulse with the protection field effect transistor.

4, Low-voltage Electronic ballast according to claim 1 is characterized in that, it also comprises the current rectifying and wave filtering circuit that is used for rectification full-bridge when ac power supply.

5, Low-voltage Electronic ballast according to claim 1 is characterized in that, described photoelectricity coupling circuit is a precision photoelectric coupler.

6, Low-voltage Electronic ballast according to claim 1, it is characterized in that, described photoelectricity coupling circuit carries out dividing potential drop by resistance (R11, R12) to the high frequency voltage that push-pull transformer (T1) secondary changes, and the variation of photoelectricity coupling circuit (Q4) luminous tube side electric current is coupled to its transistor side, when photoelectricity coupling circuit (Q4) luminous tube electric current is changed, its transistor conduct resistance changes thereupon, and makes push-pull transformer electric current power output produce respective change by pulse width modulation circuit (PWM).