JPH07135084A - Discharge lamp lighting device - Google Patents

Abstract

PURPOSE:To improve power factor in a simple circuit constitution, form a switching element compact, and achieve low manufacturing cost. CONSTITUTION:A series circuit of a pair of capacitors 25, 26 is connected between output terminals of a full-wave rectification circuit 2. Both ends of the series circuit of the capacitors 25, 26 are connected to both ends of a series circuit of a pair of switching elements 7, 8 through normal direction diodes 28, 29 respectively, and connection points of the capacitors 25, 26 are connected to connection points of the switching elements 7, 8 through a choke coil 31. An inductance of the choke coil 31 is set large to charge the smoothing capacitors 25, 26 through the diodes 28, 29 at the peak of a voltage of an AC power supply 1.

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 using a half-bridge type or full-bridge type inverter circuit.

[0002]

2. Description of the Related Art A conventional discharge lamp lighting device using a half-bridge type or full-bridge type inverter circuit
FIG. 10 shows an example of a device that can improve the power factor with a simple circuit configuration (for example, Japanese Unexamined Patent Publication No. Hei 4 (1999) -242242).
-315796). In FIG. 10, 1 is an AC power source, 2
Is a full-wave rectifier circuit composed of a diode bridge, 3
Is a half-bridge type inverter circuit, which is connected to the output terminal of the full-wave rectifier circuit 2 via a diode 4 and a choke coil 5.

The inverter circuit 3 includes a series circuit of a pair of switching elements 7 and 8, a series circuit of a pair of DC dividing capacitors 9 and 10 having a smoothing function, and a winding 1.
Transformer 1 having 1a and feedback windings 11b and 11c
1, a resistor 12, 13, a feedback diode 14, 15 connected in parallel with the switching element 7, 8 respectively, and a choke coil 16. A discharge lamp 19 is connected to the output terminal of the inverter circuit 3. Reference numeral 21 is a starting capacitor, and 22 is a diode.

Next, the operation will be described. When the AC power supply 1 is turned on, electric power is supplied from the full-wave rectifier circuit 2 to the inverter circuit 3 via the diode 4 and the choke coil 5.
When the switching element 8 is turned on, a chopping current flows from the positive electrode side of the output terminal of the full-wave rectifier circuit 2 to the negative electrode side through the diode 4, the switching element 8 and the choke coil 5. As a result, electromagnetic energy is stored in the choke coil 5.

A pair of DC dividing capacitors 9 and 10 are also provided.
Is applied with input power from the diode 4 and the feedback diode 14, and the voltage is divided by the capacitors 9 and 10. When the switching element 8 is turned off, the electromagnetic energy stored in the choke coil 5 is closed by the diode 22, the DC division capacitors 9 and 10, and the choke coil 5 and the DC division capacitors 9 and 10 are closed.
Is released to. As a result, the DC division capacitors 9, 10
Electromagnetic energy from the choke coil 5 is superimposed on the input power supply voltage applied to
The voltage across the series circuit of 10 is boosted. That is,
The series closed loop circuit composed of the choke coil 5, the diode 22 and the DC dividing capacitors 9 and 10 functions as a boost chopper circuit.

Next, when the switching element 7 is turned on, the inverter circuit 3 oscillates using the DC dividing capacitors 9 and 10 as power sources. When the inverter circuit 3 oscillates, when the switching element 8 is turned on, a combined current of the chopping current from the full-wave rectifier circuit 2 and the current due to the inverter operation flows through the switching element 8. Therefore, in the case of this conventional example, the power factor can be improved with a simple circuit configuration as compared with the discharge lamp lighting device in which the chopper circuit is separately used.

The pair of DC dividing capacitors 9,
Although 10 has a smoothing function, the pair of capacitors 9 and 10 are capacitors without a smoothing function, and instead, the smoothing capacitor 23 is connected in parallel to the series circuit of the pair of DC dividing capacitors 9 and 10 as shown by the chain line. Sometimes connected.

[0008]

However, in the conventional circuit, since the current of the inverter circuit 3 and the combined current of the chopper circuit flow through the switching element 8, the current flowing through the switching element 8 becomes large and the power loss becomes large. Becomes
Therefore, a large switching element 8 is required,
There was a problem of high cost.

In view of the above problems, the present invention can improve the power factor with a simple circuit configuration, and at the same time, the switching element can be made as small as possible and the manufacturing cost can be reduced.

[0010]

The first technical means of the present invention for solving this technical problem is to provide an inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor, In a discharge lamp lighting device in which a discharge lamp 19 is connected to an output terminal of an inverter circuit 3 connected to an AC power source 1 via a full-wave rectifier circuit 2, a pair of capacitors is provided between output terminals of the full-wave rectifier circuit 2. A series circuit of 25 and 26 is connected, and both ends of the series circuit of the capacitors 25 and 26 are connected to both ends of the series circuit of the pair of switching elements 7 and 8 through forward diodes 28 and 29, respectively. At the same time, the connection point of the capacitors 25 and 26 and the connection point of the pair of switching elements 7 and 8 are connected via the choke coil 31, and the peak of the voltage of the AC power supply 1 is reached. To charge the smoothing capacitor via the diode 29, choke coil 31
The inductance of is set to a large value.

In a second technical means of the present invention, an inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor is provided with an AC power supply 1 and a full-wave rectification circuit 2.
In the discharge lamp lighting device in which the discharge lamp 19 is connected to the output terminal of the inverter circuit 3, the pair of capacitors 25 and 26 are provided between the output terminals of the full-wave rectifier circuit 2.
Is connected to both ends of the series circuit of the capacitors 25 and 26 through forward diodes 28 and 29, respectively, and to both ends of the series circuit of the pair of switching elements 7 and 8. The connection points of the capacitors 25 and 26 and the connection points of the pair of switching elements 7 and 8 are connected via a choke coil 31, and the smoothing is performed via diodes 28 and 29 at the time when the voltage of the AC power supply 1 reaches the peak. The inductance of the choke coil 31 is set to be large so as to charge the capacitor, and the choke coil 41 is connected in series to the smoothing capacitor.

In a third technical means of the present invention, an inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor is connected to an AC power source 1 with a full-wave rectifying circuit 2.
In the discharge lamp lighting device in which the discharge lamp 19 is connected to the output terminal of the inverter circuit 3, the pair of capacitors 25 and 26 are provided between the output terminals of the full-wave rectifier circuit 2.
Is connected to both ends of the series circuit of the pair of switching elements 7 and 8 via the choke coils 33 and 34 and the forward diodes 28 and 29, respectively. Connected,
The choke coils 33 and 34 are formed on the same iron core, the connection points of the capacitors 25 and 26 and the connection points of the pair of switching elements 7 and 8 are connected, and between the choke coil 33 and the choke coil 34. , Capacitor 4
2 is connected.

[0013]

[Function] The output voltage of the full-wave rectifier circuit 2 is changed to the capacitor 25,
The voltage is divided into two by 26, and the voltage divided into two causes a current to flow through the choke coils 31, 33, 34 to store energy in the choke coils 31, 33, 34. Even when the switching elements 7 and 8 are turned on and off, the current of the inverter circuit 3 and the combined current of the chopper circuit do not flow through the switching element 8.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. As shown in FIG. 1, a series circuit of a pair of capacitors 25 and 26 is connected between the output terminals of a full-wave rectifier circuit 2, Both ends of the series circuit of 25 and 26 are connected to both ends of the series circuit of the pair of switching elements 7 and 8 via diodes 28 and 29 in the forward direction, respectively, and the connection point of the capacitors 25 and 26 and the A connection point between the pair of switching elements 7 and 8 is connected via a choke 31.

The choke coil 31 has a large inductance, and the smoothing capacitor 23 is charged through the diodes 28 and 29 at the time when the voltage of the AC power source 1 reaches its peak. A choke coil 41 is connected in series with the smoothing capacitor 23. Therefore, the output voltage of the full-wave rectifier circuit 2 is divided into two by the capacitors 25 and 26, and the divided voltage causes a current to flow through the choke coil 31 via the switching element 8 and the diode 29, and the choke coil 3
Energy is stored in 1 and the capacitor 23 is charged. Then, when the switching element 8 is turned on, a current flows in a loop of the capacitor 26, the choke coil 31, the switching element 8 and the diode 29 as shown in FIG. 2, and when the switching element 8 is turned off and the diode 14 is turned on, FIG. Capacitor 26,
A current flows in a loop of the choke coil 31, the diode 14, the choke coil 41, the capacitor 23, and the diode 29. When the switching element 7 is turned on, a current flows through the loop of the capacitor 25, the diode 28, the switching element 7 and the choke coil 31, as shown in FIG. 4, and when the switching element 7 is turned off and the die order 15 is turned on, A current flows in a loop of the capacitor 25, the diode 28, the choke coil 41, the capacitor 23, the diode 15, and the choke coil 31, as shown in FIG. Further, the current of the choke coil 31, the ON period of the switching element 8, the ON period of the switching element 7, the ON period of the diode 14, the ON period of the diode 15, the current of the choke coil 16, the combined current of the switching element 8 and the capacitor 15, The combined current of the switching element 7 and the capacitor 14 is as shown in FIG.

The energy stored in the choke coil 31 is determined by the inductance of the choke coil 31 and the switching frequency of the switching elements 7 and 8, and the power supply voltage of the AC power supply 1 has the waveform shown in FIG. Then, if the inductance of the choke coil 31 is relatively small, the input current of the choke coil 31 is as shown in FIG.
Although the waveform is as shown in (c), the choke coil 31
Has a large inductance, the boosting operation is insufficient and charging cannot be performed up to the peak value of the voltage of the AC power supply 1 due to chopping. In this case, at the time when the voltage of the AC power supply 1 reaches the peak, the diodes 28 and 29 are used. Since the capacitor 23 is directly charged, the input current of the choke coil 31 has a waveform as shown in FIG. However, even in this case, the power factor is improved.

Therefore, the inductance of the choke coil 31 is small (the input current of the choke coil 31 is as shown in FIG.
In the case of (C)), if the power supply voltage of the AC power supply 1 increases by 10%, the input current of the choke coil 31 increases by 10%,
What in Win is [Vin (10% up) x Iin
(10% up)], which means an increase of 20%, the voltage of the capacitor 23 changes by 20%.
Since the choke coil 31 has a large inductance, the voltage of the capacitor 23 is determined by the peak voltage of the AC power supply 1, and the voltage of the capacitor 23 changes only 10% with respect to the change of 10% in the power supply voltage of the AC power supply 1. Become. Therefore, the voltage of the capacitor 23 can be reliably determined by setting the inductance of the choke coil 31 to be large.

If the choke coil 41 is not provided, the capacitors 9 and 10 are charged by the currents flowing through the switching elements 7 and 8, and the smoothing capacitor 23 is supplied via the diodes 28 and 29 regardless of whether the switching elements 7 and 8 are on or off. The peak value of the current flowing in the choke coil 31 may become too high, and the peak value of the input current of the choke coil 31 becomes high as shown in FIG.
Since the choke coil 41 is connected in series with the choke coil 41, the peak value of the input current of the choke coil 31 becomes low as shown in FIG.

FIG. 8 shows another embodiment of the full-wave rectifier circuit 2.
A series circuit of a pair of capacitors 25 and 26 is connected between the output terminals of the pair of capacitors 25 and 26, and both ends of the series circuit of the capacitors 25 and 26 are connected via the chokes 33 and 34 and the forward direction diodes 28 and 29, respectively. Switching element 7, 8
Is connected to both ends of the series circuit, and the connection point of the capacitors 25 and 26 and the pair of switching elements 7,
8 connection points are connected. In other respects, the configuration is the same as that of the above-described embodiment, the inductance of the choke coil 31 is set to be large as in the above-described embodiment, and the choke coil 41 is connected in series to the smoothing capacitor 23.

In the case of this embodiment, the noise generated from the inverter circuit 3 is reduced. That is, the diodes 28, 2
9 is turned on and off at a high frequency, the high frequency voltage is generated at the points a, b, and c.
As the length becomes longer, the radio noise may increase. Therefore, the choke coil is divided into choke coils 33 and 34, and the middle point e of the half bridge is connected to the connection point of the capacitors 25 and 26. The loop in which a current flows when the switching elements 7 and 8 are turned on and off is the same as in the case of FIG. 1, and energy is accumulated in the choke coils 33 and 34 instead of the choke coil 31 to charge the capacitor 23. . Point e is full-wave rectifier circuit 3
The output voltage of 2 is divided into two, the high frequency component is small, and the point d is the same, so that the noise does not become high even if the line to the discharge lamp 19 is longer than the point d.

FIG. 9 shows another embodiment in which choke coils 33 and 34 are formed on the same iron core, and a capacitor 42 is connected between the choke coil 33 and the choke coil 34. In other respects, the configuration is similar to that of the embodiment of FIG. 8, the inductance of the choke coil 31 is set to be large, and the choke coil 41 is connected in series to the smoothing capacitor 23 as in the case of the above embodiment.

In the case of this embodiment, the choke coil 33,
If there is a leakage inductance between 34, an oscillating voltage is generated by the capacitance between the leakage inductance and the choke coils 33, 34, and the voltage applied to the diodes 28, 29 is increased. However, the capacitor 42 generates the oscillating voltage. Prevent. In the above embodiment,
The pair of capacitors 9 and 10 are capacitors without smoothing function, and the smoothing capacitor 23 is connected in parallel to the series circuit of the pair of DC dividing capacitors 9 and 10. However, instead of this, the pair of DC dividing capacitors 9 and 10 are connected. The smoothing capacitor 23 may be omitted by providing 10 with a smoothing function.

In the above embodiment, NPN type transistors are used as the switching elements 7 and 8.
The switching elements 7 and 8 are not limited to this, and a metal oxide film field effect transistor (MOSFET) or other switching elements may be used. Further, instead of the diodes 14 and 15, MOSFET parasitic diodes may be used.

Although the half-bridge type inverter circuit 3 is used in the above embodiment, the inverter circuit 3 may be replaced by a full-bridge type inverter circuit.

[0025]

According to the present invention, since the current of the inverter circuit 3 and the combined current of the chopper circuit do not flow through the switching element 8, the power factor can be improved with a simple circuit configuration and at the same time, the switching element 7 can be achieved. , 8 will be as small as possible, and the manufacturing cost will be low.

Moreover, since the inductance of the choke coil 31 is large, the capacitor 23 is directly charged through the diodes 28 and 29 at the time when the voltage of the AC power source 1 reaches its peak, so that the power source voltage of the AC power source 1 changes. On the other hand, the change in the voltage of the capacitor 23 can be suppressed low, and the voltage of the capacitor 23 can be reliably determined.

Further, since the choke coil 41 is connected in series with the smoothing capacitor, the peak value of the input current of the choke coil 31 can be lowered. Further, a capacitor 42 is provided between the choke coil 33 and the choke coil 34.
Is connected to prevent the generation of the oscillating voltage due to the leakage inductance and the capacitance between the choke coils 33 and 34.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram for explaining the operation.

FIG. 3 is a circuit diagram for explaining an operation.

FIG. 4 is a circuit diagram for explaining the operation.

FIG. 5 is a circuit diagram for explaining the operation.

FIG. 6 is a waveform diagram for explaining the operation.

FIG. 7 is a waveform diagram for explaining the operation.

FIG. 8 is a circuit diagram showing another embodiment.

FIG. 9 is a circuit diagram showing another embodiment.

FIG. 10 is a circuit diagram showing a conventional example.

[Explanation of symbols]

 1 AC Power Supply 2 Full Wave Rectifier Circuit 3 Inverter Circuit 7 Switching Circuit 8 Switching Circuit 19 Discharge Lamp 25 Capacitor 26 Capacitor 28 Diode 29 Diode 31 Choke Coil 33 Choke Coil 34 Choke Coil 41 Choke Coil 42 Capacitor

Claims (3)

[Claims] 1. An inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor is connected to an AC power source 1 via a full-wave rectifier circuit 2 and is discharged to an output terminal of the inverter circuit 3. In the discharge lamp lighting device to which the electric lamp 19 is connected, a pair of capacitors 2 is provided between the output terminals of the full-wave rectifier circuit 2.
5 and 26 are connected in series, and the capacitors 25 and 2 are connected.
Both ends of the series circuit of 6 are diodes 28,
Is connected to both ends of the series circuit of the pair of switching elements 7 and 8 via 29, and the capacitor 25,
The connection point of 26 and the connection point of the pair of switching elements 7 and 8 are connected via a choke coil 31, and the diodes 28 and 29 are connected at the time when the voltage of the AC power supply 1 reaches the peak.
A discharge lamp lighting device, wherein the inductance of the choke coil 31 is set to a large value so as to charge the smoothing capacitor via the. 2. An inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor is connected to an AC power source 1 via a full-wave rectifier circuit 2 and is discharged to an output terminal of the inverter circuit 3. In the discharge lamp lighting device to which the electric lamp 19 is connected, a pair of capacitors 2 is provided between the output terminals of the full-wave rectifier circuit 2.
5 and 26 are connected in series, and the capacitors 25 and 2 are connected.
Both ends of the series circuit of 6 are diodes 28,
Is connected to both ends of the series circuit of the pair of switching elements 7 and 8 via 29, and the capacitor 25,
The connection point of 26 and the connection point of the pair of switching elements 7 and 8 are connected via a choke coil 31, and the diodes 28 and 29 are connected at the time when the voltage of the AC power supply 1 reaches the peak.
The discharge lamp lighting device is characterized in that the inductance of the choke coil 31 is set to a large value so that the smoothing capacitor is charged through the choke coil 41, and the choke coil 41 is connected in series to the smoothing capacitor. 3. An inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 and a smoothing capacitor is connected to an AC power source 1 via a full-wave rectifier circuit 2 and is discharged to an output terminal of the inverter circuit 3. In the discharge lamp lighting device to which the electric lamp 19 is connected, a pair of capacitors 2 is provided between the output terminals of the full-wave rectifier circuit 2.
5 and 26 are connected in series, and the capacitors 25 and 2 are connected.
Both ends of the series circuit of 6 are choke coils 33 and 34, respectively.
And the diodes 28 and 29 in the forward direction are connected to both ends of the series circuit of the pair of switching elements 7 and 8, and choke coils 33 and 34 are formed on the same iron core, and the capacitors 25 and 26 are connected. A discharge lamp lighting device characterized in that a point and a connection point of the pair of switching elements 7 and 8 are connected, and a capacitor 42 is connected between the choke coil 33 and the choke coil 34.