CN101742795A - electronic ballast - Google Patents

Abstract

An electronic ballast comprises an input filter, a DC-DC flyback converter and a DC-AC full-bridge inverter circuit which are connected in turn in a cascade manner, wherein the front end of the input filter is connected with an accumulator battery, a sustained arc circuit and a multivoltage parallel structure firing circuit are in parallel connection on the DC-AC full-bridge inverter circuit; the multivoltage parallel structure firing circuit comprises a multivoltage circuit, a booster circuit, a high voltage barrier diode and a relay; the output end of the multivoltage circuit is connected with the sustained arc circuit and the booster circuit; and the booster circuit is in parallel connection with the high voltage barrier diode and a high pressure gas discharge lamp, and the high pressure gas discharge lamp and the relay are in connection. The beneficial effects of the invention are as follows: the volume of the ignition transformer is reduced, the overall efficiency of the electronic ballast of the high pressure gas discharge lamp is increased; the voltage value of the storage capacitor in the sustained arc circuit is increased so as to more effectively complete the function of arc maintenance and increase the primary ignition success rate of the high pressure gas discharge lamp; and the overall cost is reduced.

Description

electronic ballast

technical field

The invention relates to an electronic ballast for a high-pressure gas discharge lamp.

Background technique

Electronic ballasts for high-pressure gas discharge lamps include a high-voltage ignition circuit and a steady-state power supply circuit. The ignition circuit and steady-state power supply circuit can generally be connected in series or in parallel. The steady-state power supply circuit includes a DC boost circuit and a full-bridge inverter circuit. The high-voltage generating circuit of the ignition circuit generally has a single-stage boost circuit and a double-stage boost circuit.

The single-stage step-up circuit in series, as shown in Figure 1, generally requires a high turn ratio. Because the high-voltage coil flows the lamp current, the wire used should not be too thin, which will make the high-voltage transformer bulky.

The parallel single-stage booster circuit, as shown in Figure 2, can make the high-voltage side coil wires very thin, but the lamp needs to be connected in series with another ballast inductor, so the volume of the electronic ballast system will also be large.

The dual-stage boost circuit, as shown in Figure 3, generates high voltage while the high-voltage side winding acts as an electronic ballast inductance, which can reduce the volume and weight of the system. The method of adding an auxiliary winding on the secondary side of the previous stage flyback transformer is adopted, but the volume and fabrication difficulty of the flyback transformer are increased.

In order to reduce the size of the transformer and generate high voltage, the existing ignition circuit adopts a double voltage series ignition circuit structure, as shown in Figure 4. The electronic ballast adopting voltage doubler series ignition circuit includes input filter, flyback converter, continuous arc circuit, full bridge inverter circuit, voltage doubler circuit, series structure ignition circuit, using flyback converter output stage voltage doubler rectifier The circuit only uses a one-stage step-up transformer, which can reduce the turn ratio of the transformer without increasing the volume of the transformer. However, during each high-voltage ignition and start-up process of the high-pressure gas discharge lamp, one of the two electrodes of the lamp tube will be fixed as the anode, and the other electrode will be fixed as the cathode. Such a high-voltage ignition circuit structure and start-up process, The service life of the high-pressure gas discharge lamp will be greatly reduced, and the efficiency of the ignition circuit will be low.

Contents of the invention

The invention solves the problem of low efficiency of the voltage doubling series ignition circuit of the existing electronic ballast, and provides an electronic ballast with high efficiency and compact structure.

Technical scheme of the present invention:

The electronic ballast includes an input filter connected in cascade connection in order to isolate the high-frequency interference between the battery and the device, a DC-DC flyback converter used to increase the DC voltage input to the battery level, A DC-AC full-bridge inverter circuit for converting high-voltage direct current into a high-voltage square wave voltage, the front end of the input filter is connected to a storage battery, and it is characterized in that: the DC-AC full-bridge inverter circuit is connected in parallel with When the two electrodes of the high-pressure gas discharge lamp are broken down, the arc-continuing circuit and the voltage doubler parallel structure ignition circuit that briefly provide energy for the high pressure gas discharge lamp; the voltage doubler parallel structure ignition circuit includes a voltage doubler circuit, a voltage booster circuit, blocking high-voltage diodes, and relays, the output end of the voltage doubling circuit is connected with a continuous arc circuit and a booster circuit, the boosting circuit is connected in parallel with blocking high-voltage diodes and high-pressure gas discharge lamps, and the high-pressure gas discharge lamps and relays in parallel;

The voltage doubling parallel structure ignition circuit is used to generate a high voltage that breaks through the two electrodes of the high pressure gas discharge lamp, and the barrier high voltage diode is used to prevent the high voltage at the ignition moment from disabling the continuous arc circuit, the voltage doubling circuit, and the DC-AC all The components of the bridge inverter circuit are burned out, and the relay is used to maintain the normal light emission of the high-pressure discharge lamp.

Further, the voltage doubler circuit includes a third capacitor, the first end of the third capacitor is connected to the output end of the DC-DC flyback converter and the anode of the first diode, and the anode of the first diode is The cathode is connected to the first end of the clamp capacitor, the anode of the second diode and the second end of the fourth capacitor, and the cathode of the second diode is connected to the second end of the third capacitor and the third diode The anode of the third diode is connected, and the cathode of the third diode is connected with the first end of the fourth capacitor, the boost circuit and the arc continuing circuit.

Further, the arc continuation circuit includes a first resistance and a fourth diode connected in parallel, the cathode of the fourth diode and the parallel end of the first resistance are connected to the first end of the sixth capacitor that stores energy, and the sixth The second terminal of the capacitor is connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the output terminal of the voltage doubler circuit.

Further, the boost circuit includes a current limiting resistor, the first end of the current limiting resistor is connected to the output end of the voltage doubler circuit, the second end of the current limiting resistor is connected to the first end of the ignition capacitor and the first end of the gas discharge tube. The second end of the ignition capacitor is connected to the ground, the second end of the gas discharge tube is connected to the first end of the low-voltage side of the ignition transformer, and the first end of the high-voltage side of the ignition transformer is connected to the first end of the blocking low-frequency capacitor The second end of the blocking low-frequency capacitor is connected to the first end of the high-pressure gas discharge lamp and one end of the relay, and the second end of the high-pressure gas discharge lamp is connected to the second end of the high-voltage side of the ignition transformer and the DC-AC full The third inductor of the bridge inverter circuit is connected, and the other end of the relay is connected with the second inductor of the DC-AC full bridge inverter circuit.

The start-up process of high-pressure gas discharge lamps is divided into four stages from transient state to steady state: voltage breakdown, glow discharge, glow to arc discharge, and arc discharge (steady state work). The specific state transition is shown in Figure 5. process. The length of the transient time is related to the power supplied to the lamp during the glow-to-arc phase. If a larger power is applied to the lamp during the glow-to-arc period, the temperature of the lamp will rise faster, and the high voltage will be shortened. The transient time of the gas discharge lamp enables the lamp tube to enter the steady state work quickly.

During start-up, the electronic ballast has to go through three stages: high voltage breakdown, current connection, preheating and arc maintenance. The high-voltage starting circuit is the basis for whether the high-pressure gas discharge lamp can be lit instantly. However, the delay of the inertia and filter circuit after the glow discharge makes it difficult for the DC converter and the detection circuit to have a faster response speed, so the electronic ballast must contain a current take-over circuit, which stores the capacitor in advance. The energy provides a large instantaneous current for the lamp to ensure a reliable transition from glow to arc.

The working process of the present invention is described as follows: In the start-up phase, the control program performs a constant-voltage closed-loop on the terminal voltage of the bus capacitor of the full-bridge inverter circuit. The output terminal of the voltage doubler circuit charges the ignition capacitor of the boost circuit through the current limiting resistor. When the voltage value at both ends of the ignition capacitor reaches the breakdown voltage of the gas discharge tube, the ignition capacitor discharges through the low voltage side of the ignition transformer, and at the same time transfers the energy to the high voltage side. The closed-loop circuit is composed of the high-voltage winding of the ignition transformer, the blocking low-frequency capacitor, and the high-pressure gas discharge lamp. The upper electrode of the high-pressure gas discharge lamp bears positive high voltage, which makes the high-pressure gas discharge lamp breakdown.

In the continuous flow stage, the circuit composed of the continuous arc circuit, the blocking high-voltage diode and the high-pressure gas discharge lamp makes the high-pressure gas discharge lamp achieve the function of maintaining the arc.

When the high-pressure gas discharge lamp enters the glow-to-arc and arc-discharge stages, the relay is closed through program control, so that 400Hz alternating current can be obtained at both ends of the lamp tube to maintain the normal light emission of the high-pressure gas discharge lamp.

Beneficial effects of the present invention: reduce the volume of the ignition voltage device, improve the overall efficiency of the electronic ballast for high-pressure gas discharge lamps; increase the voltage value of the energy storage capacitor in the arc-continuing circuit, and more effectively complete the arc-maintaining function , improve the success rate of one-time ignition of the high-pressure gas discharge lamp; reduce the overall cost.

Description of drawings

Fig. 1 is a schematic structural diagram of a high-pressure gas discharge lamp connected in series with the high-voltage side of an ignition coil.

Fig. 2 is a schematic structural diagram of a high-pressure gas discharge lamp connected in parallel with the high-voltage side of the ignition coil.

Fig. 3 is a schematic structural diagram of a two-stage boost ignition circuit for a high-pressure gas discharge lamp.

Fig. 4 is a schematic diagram of an existing voltage doubling series ignition circuit.

Fig. 5 is a schematic diagram of the transient transition process of the high-pressure gas discharge lamp from electrode breakdown to constant power steady state operation.

Fig. 6 is a schematic circuit diagram of the present invention.

Detailed ways

Referring to Fig. 6, the electronic ballast includes an input filter 2 connected in cascade connection in order to isolate the high-frequency interference between the storage battery 1 and the device, and a DC input filter 2 used to increase the DC voltage input to the battery 1 level. -DC flyback converter 4, a DC-AC full-bridge inverter circuit 6 for converting high-voltage direct current into high-voltage square wave voltage, the front end of the input filter 2 is connected to a battery 1, and the DC-AC full-bridge The inverter circuit 6 is connected in parallel with an arc-continuing circuit 5 and an ignition circuit 3 with a double-voltage parallel structure that briefly provides energy for the high-pressure gas discharge lamp when the two electrodes of the high-pressure gas discharge lamp are broken down; Ignition circuit 3 comprises voltage doubler circuit, booster circuit, blocking high voltage diode D5, relay, and the output end of described voltage doubler circuit is connected with continuous arc circuit 5 and booster circuit, and described booster circuit is connected with blocking high voltage diode D5 and high voltage A gas discharge lamp is connected in parallel, and the high-pressure gas discharge lamp is connected in parallel with a relay;

The ignition circuit 3 with double voltage parallel structure is used to generate a high voltage that breaks down the two electrodes of the high-pressure gas discharge lamp, and the high-voltage blocking diode D5 is used to prevent the high voltage at the ignition moment from switching the arc-continuing circuit 5, voltage doubler circuit, DC - The elements of the AC full-bridge inverter circuit 6 are burnt out, and the relay is used to maintain the normal light emission of the high-pressure discharge lamp.

The voltage doubler circuit includes a third capacitor C3, the first end of the third capacitor C3 is connected to the output end of the DC-DC flyback converter 4 and the anode of the first diode D1, and the first diode The cathode of the tube D1 is connected to the first end of the clamping capacitor Co, the anode of the second diode D2 and the second end of the fourth capacitor C4, and the cathode of the second diode D2 is connected to the first end of the third capacitor C3. The two terminals are connected to the anode of the third diode D3 , and the cathode of the third diode D3 is connected to the first terminal of the fourth capacitor C4 , the boost circuit and the arc continuing circuit 5 .

The arc continuation circuit 5 includes a first resistor R1 and a fourth diode D4 connected in parallel, the cathode of the fourth diode D4 and the parallel terminal of the first resistor R1 are connected to the first end of the sixth capacitor C6 that stores energy, The second terminal of the sixth capacitor C6 is connected to the first terminal of the second resistor R2, and the second terminal of the second resistor R2 is connected to the output terminal of the voltage doubler circuit.

The boost circuit includes a current limiting resistor R3, the first end of the current limiting resistor R3 is connected to the output end of the voltage doubler circuit, the second end of the current limiting resistor R3 is connected to the first end of the ignition capacitor C5 and the gas discharge tube The first end of S.G is connected, the second end of the ignition capacitor C5 is grounded, the second end of the gas discharge tube S.G is connected to the first end of the low-voltage side of the ignition transformer T2, and the first end of the high-voltage side of the ignition transformer T2 is connected to the first end of the ignition transformer T2. The first end of the blocking low-frequency capacitor C7 is connected, the second end of the blocking low-frequency capacitor C7 is connected to the first end of the high-pressure gas discharge lamp and one end of the relay, and the second end of the high-pressure gas discharge lamp is connected to the ignition transformer T2. The second end of the high-voltage side is connected to the third inductor L3 of the DC-AC full-bridge inverter circuit 6 , and the other end of the relay is connected to the second inductor L2 of the DC-AC full-bridge inverter circuit 6 .

The working process of the present invention is described as follows: In the start-up phase, the control program performs a constant-voltage closed-loop on the terminal voltage of the bus capacitor of the full-bridge inverter circuit 6 . The output terminal of the voltage doubler circuit charges the ignition capacitor C5 of the boost circuit through the current limiting resistor R3. When the voltage value at both ends of the ignition capacitor C5 reaches the breakdown voltage of the gas discharge tube S.G, the ignition capacitor C5 passes through the low-voltage side of the ignition transformer T2 discharge while transferring energy to the high voltage side. The closed-loop circuit is composed of the ignition transformer T2 high-voltage winding, the blocking low-frequency capacitor C7, and the high-pressure gas discharge lamp. The upper electrode of the high-pressure gas discharge lamp bears positive high voltage, which makes the high-pressure gas discharge lamp breakdown.

During the freewheeling phase, the sixth capacitor C6 storing energy in the arc continuing circuit 5 passes through the loop composed of the fourth diode D4, the second resistor R2, the blocking high voltage diode D5, the high pressure gas discharge lamp, the third inductor L3 and S4 To make the high-pressure gas discharge lamp achieve the function of maintaining the arc.

When the high-pressure gas discharge lamp enters the glow-to-arc and arc-discharge stages, the relay is closed through program control, so that 400Hz alternating current can be obtained at both ends of the lamp tube to maintain the normal light emission of the high-pressure gas discharge lamp.

The content described in the embodiments of this specification is only an enumeration of the implementation forms of the inventive concept. The protection scope of the present invention should not be regarded as limited to the specific forms stated in the embodiments. The protection scope of the present invention also extends to the field Equivalent technical means that the skilled person can think of based on the concept of the present invention.

Claims (4)

1. Electronic ballast, including the input filter used to cut off the high-frequency interference between the battery and the device connected in series, and the DC-DC flyback conversion used to increase the DC voltage input to the battery level A device, a DC-AC full-bridge inverter circuit for converting high-voltage direct current into a high-voltage square wave voltage, the front end of the input filter is connected to a storage battery, and it is characterized in that: the DC-AC full-bridge inverter circuit is connected in parallel When the two electrodes of the high-pressure gas discharge lamp are broken down, an arc-continuing circuit and a voltage-doubler parallel structure ignition circuit briefly providing energy for the high-pressure gas discharge lamp are connected; the voltage doubler parallel structure ignition circuit includes a voltage doubler circuit, Booster circuit, blocking high-voltage diode, relay, the output end of the voltage doubler circuit is connected with a continuous arc circuit and a boosting circuit, the boosting circuit is connected in parallel with the blocking high-voltage diode and the high-pressure gas discharge lamp, and the high-pressure gas discharge lamp in parallel with the relay; The voltage doubling parallel structure ignition circuit is used to generate a high voltage that breaks through the two electrodes of the high pressure gas discharge lamp, and the barrier high voltage diode is used to prevent the high voltage at the ignition moment from disabling the continuous arc circuit, the voltage doubling circuit, and the DC-AC all The components of the bridge inverter circuit are burned out, and the relay is used to maintain the normal light emission of the high-pressure discharge lamp. 2. The electronic ballast according to claim 1, wherein the voltage doubling circuit comprises a third capacitor, the first end of the third capacitor is connected to the output end of the DC-DC flyback converter and the first end of the third capacitor. The anode of a diode is connected, the cathode of the first diode is connected with the first end of the clamp capacitor, the anode of the second diode and the second end of the fourth capacitor, the second diode The cathode of the third diode is connected with the second terminal of the third capacitor and the anode of the third diode, and the cathode of the third diode is connected with the first terminal of the fourth capacitor, the boost circuit and the arc continuing circuit. 3. The electronic ballast according to claim 1 or 2, characterized in that: the arc continuing circuit comprises a first resistor and a fourth diode connected in parallel, the cathode of the fourth diode and the first resistor The parallel terminal is connected to the first terminal of the sixth capacitor for storing energy, the second terminal of the sixth capacitor is connected to the first terminal of the second resistor, and the second terminal of the second resistor is connected to the output terminal of the voltage doubler circuit. 4. The electronic ballast according to claim 3, characterized in that: the boost circuit includes a current limiting resistor, the first end of the current limiting resistor is connected to the output end of the voltage doubler circuit, and the current limiting resistor The second end of the ignition capacitor is connected to the first end of the ignition capacitor and the first end of the gas discharge tube, the second end of the ignition capacitor is grounded, the second end of the gas discharge tube is connected to the first end of the low-voltage side of the ignition transformer, and the The first end of the high-voltage side of the ignition transformer is connected to the first end of the blocking low-frequency capacitor, the second end of the blocking low-frequency capacitor is connected to the first end of the high-pressure gas discharge lamp and one end of the relay, and the first end of the high-pressure gas discharge lamp The two ends are connected with the second end of the high-voltage side of the ignition transformer and the third inductance of the DC-AC full-bridge inverter circuit, and the other end of the relay is connected with the second inductance of the DC-AC full-bridge inverter circuit.

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