JPH0817583A - Electric discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To reduce the ripple component of input current by adding simple secondary winding to the inductance of a filter circuit laid between a rectification circuit and an inverter circuit. CONSTITUTION:An inductor 28 is formed out of primary winding 29 and secondary winding 30. If only the primary winding 29 is used, input current from an AC power supply 20 is determined by the capacitance of a capacitor 31 and the inductance of the winding 29. Thus, the current comes to have a sine waveform with a high-frequency ripple component. Thus, the winding 30 is added to the inductor 28 and current having polarity reverse to current flowing to a feed inductor 27 is thereby made to flow to the secondary winding 30. The current flowing to the primary winding 29 of the inductor 28 has a large DC component with a less ripple component. On the other hand, the current flowing to the winding 30 contains a very large ripple component having approximately the same phase as the current flowing to the winding 29, and generated magnetic field largely depends on the ripple component. Thus, another secondary winding with the number of turns extremely smaller than the secondary wining 30 is added to offset the ripple in the primary winding 29.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a discharge lamp lighting device having an inverter circuit.

[0002]

2. Description of the Related Art Conventionally, a discharge lamp lighting device having a circuit configuration as shown in FIG. 3 is known (Japanese Patent Laid-Open No. 3-276).
598). In this case, the rectifier circuit 3 is connected to the AC power supply 1 via the filter circuit 2, and the discharge lamp 6 is connected to the inverter circuit 5 connected to the rectifier circuit 3 via the chopper circuit 4.

The inverter circuit 5 includes two transistors 7 and 8 connected in series, diodes 9 and 10 connected in antiparallel to both transistors 7 and 8, and two capacitors 11 connected in series. 12 and transformer 13
And a series connection point of two transistors 7 and 8, and
A secondary winding 13b of a transformer 13 in which a primary winding 13a is connected between the two capacitors 11 and 12 connected in series.
The discharge lamp 6 is connected to. Also, transformer 1
The feedback winding 13c of No. 3 is connected between the base and the emitter of the transistor 7 through the resistor 14, and the feedback winding 13d is connected between the base and the emitter of the transistor 8 through the resistor 15. Reference numerals 16 and 17 denote start-up resistors.

On the other hand, since the chopper circuit 4 comprises the smoothing capacitor 18, the transistor 8, the inductor 19 and the diode 9, the transistor 8 and the diode 9 are also used as the inverter circuit 5 and the chopper circuit 4.

In this circuit, the AC voltage input from the AC power supply 1 to the rectifier circuit 3 through the filter circuit 2 is full-wave rectified by the rectifier circuit 3. When the pulsating voltage is applied to the chopper circuit 4, the charging current flows into the smoothing capacitor 18 through the inductor 19 and the diode 9. When a current flows through one of the starting resistors 17 and the transistor 8 turns on, the smoothing capacitor 18 causes the capacitor 1 to be turned on.
1, a current flows through the primary winding 13a of the transformer 13 and the transistor 8, and the resonance system including the transformer 13 and the two capacitors 11 and 12 starts electrical oscillation.
At first, a voltage for turning on the transistor 8 and turning off the transistor 7 is induced in the feedback windings 13c, 13d of the transformer 13. However, due to the electric vibration of the resonance system, both transistors 7, 8 are turned on and off alternately. Repeat.

When the transistor 8 is on, the current flowing through the inductor 19 is limited by the inductance, but increases with time. In addition to this current, a current from the smoothing capacitor 18 through the resonance system also flows through the transistor 8. Then, when the transistor 8 is turned off, the energy stored in the inductor 19 is discharged to the smoothing capacitor 18 through the diode 9, and at the same time, the transistor 7 is turned on. Since the resonance system continues to vibrate electrically, the chopper circuit 4 will be used thereafter.
The inverter circuit 5 repeats the above-described operation, and the discharge lamp 6 maintains lighting.

When the instantaneous value of the AC power supply 1 is low, the rate of increase of the current flowing through the inductor 19 is low, and the transistor 8
The energy stored in the inductor 19 at the time of turn-off is low. Therefore, the charging voltage of the smoothing capacitor 18 is low and the input current to the load is small, but conversely, when the instantaneous value of the AC power supply 1 is high, the input current to the load is large, so the input current is The waveform is similar to the waveform of the AC power supply 1. Therefore, the power factor of the power supply input is high, and the generation of harmonic components can be suppressed to a low level.

[0008]

In the discharge lamp lighting device configured as described above, since a high frequency current flows in the inverter circuit, it is important to sufficiently suppress ripples in the filter circuit and keep a clean input current waveform. However, for that reason, there is a problem that the filter circuit becomes large in size.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a discharge lamp lighting device capable of obtaining a high input power factor and suppressing a harmonic component of a power supply input current to be small while having a small size and a simple structure. It is in.

[0010]

According to the present invention, in order to achieve the above-mentioned object, a smoothing capacitor is connected in parallel between output terminals of a rectifying circuit for rectifying an AC power supply voltage via an inductor of a filter circuit. A series connection body of the first switching element and the second switching element is connected in parallel to the capacitor, a diode is connected in antiparallel to each of the first switching element and the second switching element, and a resonance capacitor, a discharge lamp, and A series connection body composed of a resonance inductor is connected in parallel to the first switch element, a starter circuit is connected to the second switch element, and the inductor of the filter circuit includes a primary winding and a reverse polarity two-pole element connected in series. A secondary winding, and the capacitor of the filter circuit is connected between the output terminals of the rectifier circuit via the primary winding. Discharge lamp lighting device is provided, wherein.

[0011]

In the present invention, since the inductor of the filter circuit is composed of the primary winding and the secondary winding of the opposite polarity connected in series to the primary winding, the filtering effect by the mutual inductance can be obtained. That is, the current flowing in the secondary winding of the filter circuit has a phase opposite to that of the current flowing in the primary winding, so that even if the number of turns in the secondary winding is small, it is canceled by the magnetic field created by both windings. The effect is obtained, and the high frequency ripple component that cannot be completely absorbed by the capacitor of the filter circuit can be efficiently removed. Since the current flowing through the primary winding is mainly a direct current component, there is almost no adverse effect on the secondary winding due to the reaction.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

The discharge lamp lighting device of the embodiment shown in FIG. 1 has a rectifier circuit 21 connected to an AC power source 20 and a filter circuit 22 and diodes 23 and 24 between output terminals a and b of the rectifier circuit 21. It is composed of a connected inverter circuit 25, a starting circuit 26 for starting the inverter circuit 25, and a power feeding inductor 27.

The inductor 28 of the filter circuit 22 includes a primary winding 29 and a secondary winding 3 of reverse polarity connected in series with the primary winding 29.
0, and the filter capacitor 31 is connected between the output terminals a and b of the rectifier circuit 21 via the primary winding 29.

On the other hand, the inverter circuit 25 has a smoothing capacitor 32 connected between its input terminals c and b, and first and second transistors 33 and 34 connected in series between the input terminals c and b. Two diodes 35 and 36 respectively connected in anti-parallel to both transistors 33 and 34,
And a capacitor 37 connected in parallel with the diode 35. Further, the primary winding 39 of the current transformer 38
A resonance inductor 40, a fluorescent lamp 41, a capacitor 42 connected between both electrodes of the fluorescent lamp 41,
A resonance circuit including the resonance capacitor 43 is connected in parallel to the first transistor 33 to form a closed loop. Further, the secondary winding 44 of the current transformer 38 is the first
Resistor 45 between the base and emitter of the transistor 33 of
And another secondary winding 46 is connected between the base-emitter of the second transistor 34 and the resistor 4
It is connected via 7.

The starting circuit 26 comprises a series connection body consisting of a resistor 48 and a capacitor 49, a diode 50 having one end connected to the series connection point of the series connection body, and a trigger element 51. The series connection body is connected in parallel to the capacitor 31, and the other end of the diode 50 is connected to the series connection point of the first and second transistors 33 and 34. The other end of the trigger element 51 is connected to the base of the second transistor 34.

The discharge lamp lighting device constructed as described above operates as follows. That is, the pulsating current voltage obtained by the full-wave rectification by the rectifier circuit 21 is
When applied to the inverter circuit 25 through the inductor 28 and the diodes 23 and 24, the charging current flows into the smoothing capacitor 32. At the same time, the charging current flows into the capacitor 49 through the resistor 48. Capacitor 49
When the charging voltage of 1 reaches the breakdown voltage of the trigger element 51, the base current is supplied from the capacitor 49 to the second transistor 34, and the second transistor 34 turns on.

Therefore, the rectifier circuit 2 is switched from the AC power source 20.
1, a current flows through the second transistor 34 through the filter circuit 28, the diode 23, and the power feeding inductor 27, and the smoothing capacitor 32 causes the resonance capacitors 43 and 42, the resonance inductor 40, and the primary winding 39 of the current transformer 38. A resonance current flows through the second transistor 34 through. At this time, the voltage induced in the secondary winding 46 of the current transformer 38 is supplied between the base and the emitter of the second transistor 34, so that the second transistor 34 maintains the ON state.

When the core of the current transformer 38 is magnetically saturated by the current flowing through the primary winding 39, the secondary winding 4
The induced voltage of 6 is eliminated, and the second transistor 34 is turned off. Then, the energy accumulated in the power feeding inductor 27 until immediately before that is discharged to the smoothing capacitor 32 through the diode 35. Due to this step-up chopper operation, the charging voltage of the smoothing capacitor 32 becomes higher than the output voltage of the rectifier circuit 21. At the same time, a resonance current flows through the resonance inductor 40 and the resonance capacitors 43 and 42. This resonance current decays with time, but then the secondary winding 44 of the current transformer 38,
Since the polarity of the voltage induced in 46 is reversed, the first transistor 33 turns on and the second transistor 34 turns off.

Next, the resonance current increases, the current transformer 38 is magnetically saturated, and the first and second transistors 3
Electrical oscillation due to resonance continues thereafter, and the transistors 33 and 34 alternately repeat on and off.

As described above, the second transistor 34
The current flowing in the power feeding inductor 27 at the time of turning on is limited by the inductance of the inductor 27 and increases with time. Then, the second transistor 34
Is turned off, the energy accumulated in the inductor 27 is discharged to the smoothing capacitor 32 through the diode 35, and both the charging voltage and the resonance voltage of the smoothing capacitor 32 rise.
The fluorescent lamp 41 starts and lights up. After that, the charging operation of the smoothing capacitor 32 and the resonance operation of the inverter circuit 25 are repeated with the on / off operation of both the transistors 33 and 34, so that the fluorescent lamp 41 maintains the lighting state.

When the instantaneous value of the AC power supply 20 is low, the rate of increase of the current flowing through the power feeding inductor 27 is low, and if the on-time is always the same, the stored energy of the inductor 27 when the second transistor 34 is turned off is: It is small, the charging voltage of the smoothing capacitor 32 is also low, and the input current to the load becomes small according to the instantaneous value of the AC power supply 20.
Conversely, when the instantaneous value of the AC power supply 20 is high, the rate of increase in the current flowing through the power feeding inductor 27 is high, and if the on-time is always the same, the stored energy in the inductor 27 when the second transistor 34 is turned off is: It is large, and the charging voltage of the smoothing capacitor 32 is high. Further, since the input current to the load also increases according to the instantaneous value of the AC power source 20,
An input current having a waveform substantially similar to the waveform of the AC power supply 20 can be obtained, the power factor of the power supply input is high, and the harmonic component of the power supply input current can be suppressed to be small.

Next, the operation of the filter circuit 22 will be described. The current flowing through the second transistor 34 in the ON state is supplied from the rectifier circuit 21 through the filter inductor 28 and the power feeding inductor 27. Some of them are supplied from the for-use capacitor 31 through the inductor 27. The combined current is controlled by the inductance of the inductor 27 and has a linearly increasing current waveform as shown in FIG.

When the second transistor 34 is turned off, the energy stored in the inductor 27 is discharged to the smoothing capacitor 32 through the diode 35 and the filter capacitor 31. After that, no current flows through the inductor 27 until the second transistor 34 is turned on. Therefore, the current flowing through the inductor 27 has an intermittent pulse waveform synchronized with the oscillation frequency of the inverter circuit 25. It is the inductor 28 and the capacitor 31 of the filter circuit 22 that smooth this current.

The inductor 28 is composed of a primary winding 29 and a secondary winding 30. If only the primary winding 29 is provided, the input current from the AC power supply 20 is the primary capacitance of the capacitor 31 and the primary winding. The waveform is as shown in FIG. 2B, which is determined by the inductance of the line 29, that is, a sine wave having a high-frequency ripple component.

Therefore, the inductor 28 is provided with a secondary winding 30, and a current having a polarity opposite to that of the current flowing through the power feeding inductor 27 is passed through the secondary winding 30. The current flowing through the primary winding 29 of the inductor 28 has a large DC component and a small ripple component as shown in FIG. On the other hand, the current flowing through the secondary winding 30 contains a very large ripple component having substantially the same phase as the ripple component of the current flowing through the primary winding 29, and the magnetic field generated by this has a ripple component. Heavily dependent. That is, the larger the ripple component is, the stronger the magnetic field becomes, so that a sufficient correction magnetic field can be obtained with a small number of turns. Since the ripple component of the primary winding current that should be canceled by this magnetic field is much smaller than the ripple component of the secondary winding current, the number of turns is much smaller than that of the primary winding. Only by adding the secondary winding, the ripple component of the primary winding current can be sufficiently canceled, and the current waveform with a small ripple component as shown in FIG. 2C can be improved.

Further, even if the degree of magnetic coupling between the primary winding 29 and the secondary winding 30 is low, the ripple component of the input current can be canceled out, so that the primary winding 29 and the secondary winding 30 have the same magnetic field. It does not have to be arranged on the core. The secondary winding 30 can be installed near the primary winding 29 as a high-frequency general-purpose air-core coil of several turns, or can be patterned on a printed board. Further, since the magnetic field generated by the ripple component of the primary winding current and the magnetic field generated by the secondary winding current are in the direction of canceling each other, even if the inductor 28 is configured by the drum core, high frequency noise may be increased, There is almost no danger of adversely affecting other elements. For this reason, it is possible to dispose them in proximity to other components, and the entire circuit can be made compact.

Furthermore, since magnetic saturation due to ripple components is eliminated as compared with the conventional structure, it can be used in a higher temperature environment, and in particular, a bulb cap mold in which a discharge lamp and its drive circuit are integrated. It can also be applied to a discharge lamp. Further, not only the inductor 28 itself can be made small, but also the filter capacitor 31
Can be made smaller than before.

In a lighting device for a power supply voltage of 120 V,
In a case where a 4 mH drum core (4 turns of secondary winding) is used for the filter inductor 28 and an 18 W fluorescent lamp 41 is used, the maximum value of the input current ripple component can be improved from 50 mA of the related art to 3 mA. did it.

The circuit configuration shown in FIG. 1 is only one example. For example, the feeding inductor 27 is deleted and the cathode of the diode 23 is connected to the connection point between the fluorescent lamp 41 and the resonance inductor 40. Modifications such as the above are possible. In this case, one of the two diodes 23 and 24 can be deleted, but in short, it suffices that the filter inductor 28 is connected to the circuit on the power supply side with respect to the inverter circuit 25.

Further, instead of connecting the inductor 28 to the positive terminal side of the rectifier circuit 21, it may be connected to the negative terminal side, or may be connected to both the positive terminal side and the negative terminal side.
Further, the inverter circuit 25 is not limited to the illustrated circuit type and may be a low power factor type.

[0032]

As described above, according to the present invention, the ripple component of the input current can be reduced only by adding a simple secondary winding to the inductor of the filter circuit connected between the rectifier circuit and the inverter circuit. Can be made.

[Brief description of drawings]

FIG. 1 is an electric circuit diagram of a discharge lamp lighting device according to an embodiment of the present invention.

FIG. 2 is an electric waveform diagram in each part of the discharge lamp lighting device according to the embodiment of the present invention.

FIG. 3 is an electric circuit diagram of a conventional discharge lamp lighting device.

[Explanation of symbols]

 21 Rectifier Circuit 22 Filter Circuit 25 Inverter Circuit 32 Smoothing Capacitor 33, 34 Transistor 40 Resonance Inductor 42 Resonance Capacitor

Claims (1)

[Claims] 1. A smoothing capacitor is connected in parallel between the output terminals of a rectifier circuit for rectifying an AC power supply voltage via an inductor of a filter circuit, and a series connection body of a first switch element and a second switch element is provided. A capacitor connected in parallel, a diode connected in antiparallel to each of the first switch element and the second switch element, and a resonance capacitor,
A series connection body including a discharge lamp and a resonance inductor is connected in parallel to the first switch element, a start circuit is connected to the second switch element, and the inductor of the filter circuit is a primary winding and an inverse winding connected in series to the inductor. A discharge lamp lighting device comprising a secondary winding having a polarity, and a capacitor of the filter circuit being connected between the output terminals of the rectifier circuit via the primary winding.