CN201131077Y - A ballast for metal halide lamps - Google Patents

Abstract

The utility model discloses an electronic ballast for a metal halide lamp, which comprises a power supply filter circuit, a secondary power supply circuit coupled to the power supply input and filter circuit, a DC step-up and constant voltage circuit, a half-bridge high-frequency inverter variable circuit, constant current PWM control circuit, and resonant ignition circuit. The electronic ballast for lighting metal halide lamps of the utility model adopts a digital circuit to control the working state of the lamp tube, so that the output power of the electronic ballast will not change with the change of the characteristics of the lamp, and the output light of the lamp is guaranteed. Efficiency solves the problems of acoustic resonance, power drift and color temperature drift; using DC power supply provided by batteries, such as solar cells, can replace some existing lighting equipment, saving a lot of power consumption and transportation costs to achieve the purpose of energy saving .

Description

A ballast for metal halide lamps

technical field

The utility model belongs to a ballast, in particular to a low-voltage ballast used for a metal halide lamp.

Background technique

Lighting metal halide lamps (metal halide lamps) as a high-efficiency light source are being gradually promoted, but their supporting electronic ballasts have always been a technical difficulty. Although the cost of ordinary high-frequency metal halide lamp ballasts is relatively high Low, but can not overcome the acoustic resonance phenomenon, resulting in unstable lamp work, arc flicker, difficult for consumers to accept. Although the low-frequency square wave lighting solution on the market has basically solved the acoustic resonance phenomenon, its high cost also hinders the promotion of this high-efficiency light source.

The Chinese utility model patent with the publication number CN2728163 granted to the applicant of this case discloses an electronic ballast for metal halide lamps, including: a filter rectifier to convert the voltage of the AC mains frequency into a DC voltage; a power Factor pull-up circuit, which outputs a constant working voltage, improves power factor, and filters out clutter; a high-voltage pulse lighting circuit generates high-voltage trigger voltage to start high-pressure gas discharge lamps; a high-frequency half-bridge drive circuit consists of a resonant A frequency-controlled digital circuit completes drive control and stabilizes the working state of the discharge lamp; a sampling circuit samples the operating frequency of the circuit; a signal processing circuit processes the sampled signal, automatically converts the frequency and controls the digital circuit; A switching power supply provides stable working voltage for the digital circuit. The electronic ballast circuit of the utility model can be hot-started instantaneously, and the discharge lamp can be operated reliably for a long time.

Utility model content

The ballast is an electronic device equipped with a lighting metal halide lamp. The circuit adopts a new circuit design and is powered by DC. It can be used in various battery (such as solar cells, etc.) power supply and other occasions.

In order to achieve the above functions, the novel circuit is realized through the following technical solutions: The electronic ballast for metal halide lamps of the present utility model includes

A power filter circuit for providing a stable low-voltage DC power supply;

The secondary power supply circuit is coupled to the power supply input and the filter circuit, and is used to take the power input and the output of the filter circuit low-voltage DC output as input, and generate a constant voltage or current as output;

DC step-up and constant voltage circuit, coupled to the power input and filter circuit, powered by the secondary power supply circuit, used to use the low-voltage DC output of the power input and the output of the filter circuit as input to generate a constant high-voltage DC output;

The half-bridge high-frequency inverter circuit is coupled to the DC boost and constant voltage circuit to provide a constant current high voltage AC output after inverting the high voltage DC output generated by the DC boost and constant voltage circuit;

A constant-current PWM control circuit for generating a control signal to control the half-bridge high-frequency inverter circuit to output constant-current high-voltage AC outputs of different powers; and,

The resonant ignition circuit is coupled to the output end of the half-bridge high-frequency inverter circuit, and generates a high-voltage signal for starting the lamp.

Preferably, it also includes a no-load protection feedback circuit, coupled between the resonant ignition circuit and the secondary power supply circuit, to feed back the state feedback signal of the resonant ignition circuit to the secondary power supply circuit, and the secondary power supply circuit The constant high voltage DC output voltage value of the control output.

Preferably, a short-circuit protection feedback circuit is also included, coupled between the metal halide lamp and the constant current PWM control circuit, to control it by sampling from the constant current PWM control circuit and feeding back to the constant current PWM control circuit.

Preferably, an anti-reverse connection circuit is also included, which is coupled between the power supply filter circuit, the secondary power supply circuit and the DC step-up and constant voltage circuit.

The electronic ballast for lighting metal halide lamps of the utility model adopts a digital circuit to control the working state of the lamp tube, so that the output power of the electronic ballast will not change with the change of the characteristics of the lamp, and the output light of the lamp is guaranteed. Efficiency solves the problems of acoustic resonance, power drift and color temperature drift; using DC power supply provided by batteries, such as solar cells, can replace some existing lighting equipment, saving a lot of power consumption and transportation costs to achieve the purpose of energy saving .

Description of drawings

The circuit block schematic diagram of Fig. 1 the utility model;

Fig. 2 is a schematic diagram of a DC step-up and constant voltage circuit according to a specific embodiment of the present invention;

3 is a schematic diagram of a constant current PWM control circuit and a short circuit protection feedback circuit according to a specific embodiment of the present invention;

Fig. 4 is a schematic diagram of a half-bridge inverter and resonant ignition circuit according to the present invention.

Detailed ways

The utility model relates to an electronic ballast for a metal halide lamp, which is used to ensure the output light efficiency of the metal halide lamp when powered by a low-voltage power supply, and solves the problems of acoustic resonance, power drift and color temperature drift, as follows In conjunction with the accompanying drawings, the features of the utility model are described in detail:

Referring to Fig. 1, the electronic ballast of the present invention includes a power supply filter circuit 1, which is used to filter out high-frequency clutter generated by some low-voltage DC power sources such as solar power supplies, thereby ensuring a high-quality low-voltage DC power supply.

The anti-reverse connection circuit 2 is connected to the output terminal of the power filter circuit 1, and is used to provide the positive and negative polarity access protection required for using a DC power supply. There are many ways to implement such an anti-reverse connection circuit in the prior art, such as Diode-based, triode-based.

The electronic ballast also includes a secondary power supply circuit 3 connected to the output end of the anti-reverse connection circuit and a DC step-up and constant voltage circuit 4, wherein the secondary power supply circuit 3 can be a DC step-up circuit for converting the connected The DC low voltage is converted to the 15V DC voltage required to drive the PWM device or drive the DC boost control device.

The DC step-up and constant voltage circuit 4 is based on a switch circuit, outputs high-voltage AC and then rectifies to obtain high-voltage DC. CMOS tubes can be used during the switching period in the switching circuit, and the switching control device is powered by the secondary power supply circuit 3. Its model, as known to those skilled in the art, has multiple options. A typical DC step-up and constant voltage circuit 4 can be seen in Figure 2, in which the frequency control IC controls the operating frequency of the MOS transistor Q1 to determine the output voltage and constant voltage.

The half-bridge inverter circuit 7 and the resonant ignition circuit 8, as shown in 4, may be based on a typical half-bridge inverter circuit and a typical resonant ignition circuit in the prior art. The half-bridge inverter circuit shown in Figure 4 has an inverter bridge composed of two Qs and Ts. Through the saturation reversal characteristics of T, the two MOS transistors Q are turned on in turn, making them work in the switching state and providing power to the lamp. Tube a high-frequency quasi-sine wave.

Its output can be controlled by a constant-current PWM control circuit 5 and a short-circuit protection feedback circuit 6, wherein the constant-current PWM control circuit 5 is coupled to the input end of the half-bridge inverter circuit to provide a switch control signal for the MOS tube, thereby The output power of the half-bridge inverter circuit is controlled, so as to control the half-bridge inverter circuit to switch between the power output of ignition and the power output of the light tube. The short-circuit protection feedback circuit 6 is coupled between the metal halide lamp and the constant current PWM control circuit 5, and is used to feed back a control signal to the constant current PWM control circuit 5 according to the state of the metal halide lamp, and control the output of the constant current PWM control circuit 5 . Fig. 3 shows such a constant current PWM control circuit 5, which controls the pulse width output to the MOS transistor Q by sampling the source resistance R of Q, so as to achieve the purpose of constant power operation. The short-circuit protection feedback circuit 6 samples the source resistance R of Q, uses an amplifier and a comparator to feed back the voltage at this point, and turns off the drive to the MOS transistor Q if an abnormal short circuit is found.

A no-load protection feedback circuit 9 can also be coupled between the resonant ignition circuit 8 and the secondary power supply circuit. The detection signal sampled from the resonant ignition circuit 8 is programmed by the amplifier logic operation in the no-load protection feedback circuit 9, and then fed back to the The control chip in the secondary power supply circuit 3 adjusts the working voltage of the half-bridge according to programming, and completes the function of high-voltage start-up.

In summary, the above are only preferred embodiments of the present utility model, and are not intended to limit the implementation scope of the present utility model. That is, all equivalent changes and modifications made according to the patent scope of the utility model should belong to the technical category of the utility model.

Claims (4)

1. An electronic ballast for metal halide lamps, characterized in that: comprising A power filter circuit for providing a stable low-voltage DC power supply; The secondary power supply circuit is coupled to the power supply input and the filter circuit, and is used to take the power input and the output of the filter circuit low-voltage DC output as input, and generate a constant voltage or current as output; DC step-up and constant voltage circuit, coupled to the power input and filter circuit, powered by the secondary power supply circuit, used to use the low-voltage DC output of the power input and the output of the filter circuit as input to generate a constant high-voltage DC output; The half-bridge high-frequency inverter circuit is coupled to the DC boost and constant voltage circuit to provide a constant current high voltage AC output after inverting the high voltage DC output generated by the DC boost and constant voltage circuit; A constant-current PWM control circuit for generating a control signal to control the half-bridge high-frequency inverter circuit to output constant-current high-voltage AC outputs of different powers; and, The resonant ignition circuit is coupled to the output end of the half-bridge high-frequency inverter circuit, and generates a high-voltage signal for starting the lamp. 2. The electronic ballast for metal halide lamps according to claim 1, further comprising a no-load protection feedback circuit, coupled between the resonant ignition circuit and the secondary power supply circuit, for switching the resonant The state feedback signal of the ignition circuit is fed back to the secondary power supply circuit, and the secondary power supply circuit controls the output voltage value of the constant high-voltage direct current output according to the feedback signal. 3. The electronic ballast for metal halide lamps according to claim 1 or 2, characterized in that: it also includes a short circuit protection feedback circuit, coupled between the metal halide lamp and the constant current PWM control circuit, through The constant current PWM control circuit samples, and then feeds back to the constant current PWM control circuit to control it. 4. The electronic ballast for metal halide lamps according to claim 3, further comprising an anti-reverse connection circuit coupled to the power supply filter circuit, the secondary power supply circuit and the DC boost and constant voltage circuit between.

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