KR100879710B1 - Electronic ballast for metal halide lamp - Google Patents

Abstract

The present invention relates to an electronic ballast for metal halide lamps in which power loss is small, light tremors are not generated, and lamp life is extended.

According to the present invention, a commercial AC power is applied and is connected to the power supply unit 10 including the filter unit 12 and the rectifier unit 14 and the rear end of the power supply unit 10, and the rectified DC direct current of a constant voltage. Is connected to a power factor adjusting unit 20 for outputting the power source and the output terminal of the first oscillator IC1 connected to a rear end of the power factor adjusting unit 20 and outputs an alternate pulse signal, and converts an alternate pulse signal into a high frequency signal. A pair of switching elements Q1 and Q2 and a charge / discharge capacitor which converts a direct current output from the power factor adjusting unit 20 into an alternating current by receiving an alternating high frequency pulse signal converted into a high frequency pulse from the transformers LT2 and LT3. A connection point between the inverter unit 31 including (C6, C7) and the two switching elements (Q1, Q2) of the inverter unit 31 to convert the AC output from the inverter unit 31 into a current controlled direct current And sequentially between the connection points between the two capacitors (C6, C7) It is connected between the choke transformer 32 and the bridge rectifier 34 which are connected in series, and between the choke transformer 32 and the bridge rectifier 34 to mutually connect the bridge rectifier 34 to a full-wave voltage rectifier circuit or a full-wave rectifier circuit. A direct current is converted into a square wave alternating current for lamp driving in accordance with the low frequency pulse signal of the second oscillator (IC2) connected to the switching switch 35 for switching and the rear rectifier of the bridge rectifier 34 to generate a low frequency pulse signal. And a full bridge inverter unit 40 applied to 60, and an igniter unit 50 connected between the full bridge inverter unit 40 and the lamp 60 to induce a high voltage to the lamp 60 at an initial stage of lighting. An electronic ballast for a metal halide lamp is provided.

Metal halides, electronic ballasts, half bridges, choke transformers

Description

Electronic ballast for metal halide lamps {Electronic ballast for metal halide lamp}

1 is a circuit diagram of an embodiment of the present invention

2 is a block diagram of a full-wave back voltage rectifying circuit according to the present invention

<Description of the symbols for the main parts of the drawings>

10. Power supply unit 20. Power factor adjustment unit

31. Inverter 32, choke transformer

34. Bridge rectifier 40. Full bridge inverter

50. Igniter 70. Voltage drop circuit

80. Ballast controller

The present invention relates to an electronic ballast for a metal halide lamp used in a commercial power source, and in more detail is small in volume and low in power loss, no light tremor occurs, lamp damage is suppressed and lamp life is extended. The present invention relates to an electronic ballast for a metal halide lamp having a new structure capable of lighting the lamp stably.

Metal halide lamps are light white and have excellent color rendering properties to clearly identify objects, and have excellent efficiency compared to incandescent lamps and halogen lamps. Therefore, they are widely used as outdoor or indoor lighting lamps. The magnetic leakage transformer used in the ballast of the conventional metal halide lamp is bulky and heavy, and has a disadvantage in that the power loss of the ballast is large due to magnetic loss, iron loss or copper loss, and the heat generation is severe. Electronic ballasts with relatively low losses have been developed and used.

On the other hand, the high-frequency type metal ballast stabilizer generates light tremors caused by the acoustic resonance phenomenon that occurs when the lamp is turned on, and when the lamp is turned on again, it is induced outside the discharge tube (primer) to cause other contacts (primer supports) and arcs. Due to the phenomenon, there are many difficulties in lighting the lamp by using high frequency, and when the output line is long, high frequency loss occurs and the output of the load decreases. To overcome this problem, the applied current must be converted to low frequency. In addition, if the metal halide lamp reaches the maximum power level immediately after lighting, the cold glass tube may be easily cracked or damaged by the load heat caused by the discharge, so the power of the lamp immediately after the lamp is turned off from the minimum power required to maintain the lighting. It is desirable to slowly reach the rating. However, the conventional ballast for metal halide lamps has a problem in that its structure is complicated, such as requiring a separate processor or using a large number of parts to satisfy such lighting conditions.

The present invention has been proposed in view of the problems of the conventional metal halide lamp as described above, while the volume is small and the power loss is small, but the light tremors are not generated when the lamp is turned on, damage to the lamp is suppressed and It is to provide an electronic ballast for a metal halide lamp with a new structure that can control the current to reliably turn on the lamp to extend the life.

According to one feature of the present invention, a commercial AC power is applied and connected to the rear end of the power supply unit 10 and the power supply unit 10 including the filter unit 12 and the rectifier unit 14, and the rectified DC It is connected to the power factor adjusting unit 20 for outputting a direct current of voltage and the output terminal of the first oscillator IC1 connected to the rear end of the power factor adjusting unit 20 and outputting an alternate pulse signal to convert the alternate pulse signal into a high frequency signal. A pair of switching elements Q1 and Q2 for converting a direct current output from the power factor adjusting unit 20 into an alternating current by applying a high frequency transformer LT2 and LT3 to be converted and an alternating high frequency pulse signal as a gate terminal; Inverter unit 31 including charge and discharge capacitors C6 and C7, and two switching elements Q1 and Q2 of the inverter unit 31 to convert the AC output from the inverter unit 31 into a current controlled direct current. ) And between the two capacitors (C6, C7) A choke transformer 32 and a bridge rectifier 34 that are sequentially connected in series, and are connected between the choke transformer 32 and the bridge rectifier 34 to connect the bridge rectifier 34 to a full-wave voltage rectifier circuit or a full-wave rectifier circuit. A direct current switch to a square wave alternating current for lamp driving in accordance with a low frequency pulse signal of a second oscillator (IC2) connected to a switching switch 35 for mutually switching to the rear end of the bridge rectifying unit 34 and generating a low frequency pulse signal. The full bridge inverter unit 40 applied to the lamp 60 and the igniter unit 50 connected between the full bridge inverter unit 40 and the lamp 60 to induce a high voltage to the lamp 60 at the initial stage of lighting. Provided is an electronic ballast for a metal halide lamp, characterized in that consisting of.

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According to another feature of the present invention, a relay driver 36 is connected to the secondary side of the choke transformer 32 so that the relay driver 36 switches by driving a relay 37 disposed adjacent to the changeover switch 35. An electronic ballast for a metal halide lamp, characterized in that the switch 35 is automatically switched.

Hereinafter, with reference to the drawings will be described a preferred embodiment of the present invention. 1 is a circuit diagram of an embodiment of the present invention. As shown, the ballast circuit of the present invention includes a power supply unit 10 is largely rectified by a direct current AC power input, a power factor adjustment unit 20 for converting a direct current into a constant current of a constant voltage, a direct current controlled DC A half-bridge DC-DC converter section comprising an inverter section 31, a choke transformer 32, and a bridge rectifying section 34 for converting the voltage into a high voltage converter, a full bridge inverter section 40 for generating low frequency alternating current for lamp driving, and an igniter. It consists of a part 50.

The power supply unit 10 is provided with a commercial power source of 220V 60Hz and is composed of a filter unit 12 for removing noise and a full-wave bridge rectifying unit 14 for converting AC into direct current. Meanwhile, a voltage drop circuit unit 70 for supplying a low voltage current to the ballast controller 80 is disposed in parallel with the power supply unit 10.

A power factor adjusting unit 20 using a dedicated IC is connected to the rear end of the power supply unit to obtain a stable voltage of DC 400V despite a change in the input voltage.

The rear end of the power factor adjusting unit 20 has a pair of high frequency transformers LT2 and LT3, a pair of switching elements Q1 and Q2, and a pair of chargers connected in series to the rear ends of the switching elements Q1 and Q2. An inverter section 31 including discharge capacitors C6 and C7 is disposed. Alternate high frequency pulse control signals are applied to the gate ends of the pair of switching elements Q1 and Q2 as follows. First, the first oscillator IC1 disposed in the ballast controller 80 outputs an alternating square wave pulse signal to two output terminals. As shown in FIG. 1, two pulse signals (control 1 OUT and control 2 OUT) output from the first oscillator IC1 are inputted to the primary side input signals (control 1 IN and control) of the high frequency transformers LT2 and LT3, respectively. 2 IN). The signal output from the secondary side of each of the high frequency transformers LT2 and LT3 is transmitted to the gate terminal of each of the pair of switching elements Q1 and Q2. That is, the alternating pulse signal output from the first oscillator IC1 is converted into a high frequency pulse signal through the high frequency transformers LT2 and LT3 and applied to the gate terminal of each of the switching elements Q1 and Q2. The choke transformer 32 and the bridge rectifying view 34 are sequentially connected in series between the connection point between the switching elements Q1 and Q2 and the connection point of the charge / discharge capacitors C6 and C7.

The choke transformer 32 has a high frequency ferrite core embedded therein, and a switching switch 35 is connected between one AC input terminal of the bridge rectifying unit 34. The contact A of the switching switch 35 is a contact for connecting the choke transformer 32 and the bridge rectifier 34 in series so that the bridge rectifier 34 functions as a full-wave rectifier circuit, and the contact B is a contact with the choke transformer 32. The bridge rectifying unit 34 blocks the bridge rectifying unit 34 so that the bridge rectifying unit 34 functions as a full-wave back voltage rectifying circuit as shown in FIG. The changeover switch 35 is operated by a relay 37, which is operated by a relay driver 36 connected to the secondary side of the choke transformer 32. Accordingly, in the initial stage of lighting of the lamp, the DC400V current input to the inverter unit 31 is converted into alternating current by the high frequency pulse signal applied through the first oscillator IC1 and the high frequency transformers LT2 and LT3, and then the choke transformer ( 32) is controlled by the current suitable for driving the lamp 60 according to the inductance capacity and frequency of the choke coil, and then consists of two diodes of the bridge rectifier 34 through the contact B of the switching switch 35 Through the full-wave voltage rectification circuit, a relatively high direct current of DC400V is obtained. This 400V is applied to the full bridge inverter unit 40 at the initial stage of lamp lighting.

However, when the lamp 60 is normally turned on, the relay driver 36 connected to the secondary side of the choke transformer 34 drives the relay 37 to automatically switch the switching switch 35 to the A contact point, thereby providing the bridge rectifier. By converting 34 into a full-wave rectifier circuit, a relatively low direct current of DC200V is applied to the full-bridge inverter unit 40 so as to supply a voltage close to the tube voltage of the lamp, thereby converting it to a minimum voltage size capable of maintaining stable lamp discharge. do.

The full bridge inverter unit 40 is connected to the rear end of the bridge rectifying unit 34, so that the low frequency pulse signal from the second oscillator IC2 of the ballast controller 80, specifically, the acoustic resonance of the lamp (light tremor) In response to a pulse signal of about 60 Hz to 400 Hz that does not cause a phenomenon, a direct current applied at the front end is converted into a low frequency alternating current for lamp driving and applied to the lamp 60. To this end, the low frequency transformer LT1, to which the output pulse of the second oscillator IC2 is applied to the primary side, and the four switching elements Q3, Q4, Q5, which are connected in a bridge form to the secondary side of the low frequency transformer LT1, A full bridge circuit consisting of Q6) is provided.

In addition, an igniter unit 50 for instantaneously applying a high voltage is disposed between the full bridge inverter unit 40 and the lamp 60. The igniter portion 50 includes a high voltage transformer 52 having a resistor R19, a capacitor C21, and an SCR connected to a primary side, and a lamp 60 connected to a secondary side. Accordingly, when the voltage charged in the capacitor C21 through the resistor R19 is rapidly discharged to the SCR through the primary side of the high voltage transformer 52, the high pressure is induced on the secondary side having a relatively large turns ratio, thereby causing the lamp 60 to be discharged. Is applied to. The discharge cycle of the SCR uses the triggering DIAC to trigger the gate of the SCR when the voltage charged to C22 through R16 exceeds the breakover voltage of the DIAC (eg 36V). Therefore, if the voltage drops below 200V after the lamp 60 is turned on, the SCR will not trigger and the operation of the igniter will be cut off when the voltage between both ends of C22 becomes below the breakover voltage of DIAC due to the partial pressure ratio of R16 and R17. .

According to the present invention described above, in controlling the metal halide lamp driving current, the choke transformer 32 and the bridge rectifying unit 34 are connected in series to the inverter unit 31, and the bridge rectifying unit 34 is switched to the switching switch 35. By switching between the full-wave back voltage rectifying circuit and the full-wave rectifying circuit simply by means of), current control and voltage control can be achieved with a simple circuit configuration suitable for driving a metal halide lamp. In addition, the existing magnetic ballast using a commercial AC power source has a merit that the current is controlled by the magnetic leakage generated by giving a gap to the core core core, there is an advantage that the stable current control is achieved, the same principle in the electronic ballast of the present invention The high frequency converted by the half-bridge switching circuit is passed through the high-frequency choke coil connected in series with the load side to enable stable current control like the conventional iron core magnetic ballast.

In addition, the choke transformer is supplied to the load through the choke transformer 32 by supplying the voltage charged in the capacitors C6 and C7 through the high speed switching using the pair of switching elements Q1 and Q2 and the capacitors C6 and C7. Since the output power is determined according to the inductance capacitance value of (32), the capacitance value of the capacitors C6 and C7, and the switching frequency, the current is controlled as compared to the secondary induction method using the transformer or PWM control method as in the prior art. The circuit configuration is simple and does not require a separate control unit for controlling the pulse width by using the processor to cope with the load condition. In addition, the use of the high frequency ferrite core in the choke transformer 32 has the advantage that the loss due to iron loss and copper loss, which is a problem of the conventional magnetic ballast, is extremely low, so that the heat generation is small and the efficiency of the ballast is increased.

Claims (2)

A commercial AC power is applied and a power supply unit 10 including a filter unit 12 and a rectifying unit 14 and a power factor adjusting unit connected to a rear end of the power supply unit 10 and outputting rectified DC to a DC of a predetermined voltage. A high frequency transformer (LT2, LT3) connected to a rear end of the power factor adjusting unit (20) and connected to an output terminal of the first oscillator (IC1) that outputs an alternate pulse signal to convert an alternate pulse signal into a high frequency signal; ) And a pair of switching elements (Q1, Q2) and charge and discharge capacitors (C6, C7) for converting a direct current output from the power factor adjusting unit 20 into an alternating current by applying an alternating high frequency pulse signal to a gate terminal. A connection point between the inverter unit 31 and the two switching elements Q1 and Q2 of the inverter unit 31 to convert an AC output from the inverter unit 31 into a current controlled direct current, and two capacitors C6. , Serially connected between connection points between C7) A switching switch connected between the transformer 32 and the bridge rectifier 34 and the choke transformer 32 and the bridge rectifier 34 to switch the bridge rectifier 34 to a full-wave voltage rectifier circuit or a full-wave rectifier circuit. And a direct current is converted into a square wave alternating current for lamp driving according to the low frequency pulse signal of the second oscillator (IC2) connected to the rear end of the bridge rectifying unit 34 and generating a low frequency pulse signal, and applied to the lamp 60. A full bridge inverter unit 40 and an igniter unit 50 connected between the full bridge inverter unit 40 and the lamp 60 to induce a high voltage to the lamp 60 at an initial stage of lighting. Electronic ballasts for metal halide lamps. The secondary drive of the choke transformer 32 is connected to a relay driver 36. The relay driver 36 drives a relay 37 disposed adjacent to the switch switch 35 so as to switch over the switch. 35. Electronic ballast for metal halide lamp, characterized in that the automatic switching.

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