JPH07296977A - Discharge lamp lighting device and dc power supply device - Google Patents

Abstract

PURPOSE:To enhance the power factor using a simple circuit configuration by inserting a capacitor between the connection point of a diode with choke coil and the connection point of a pair of switching elements. CONSTITUTION:A capacitor 33 is inserted between the output terminals of a full wave rectifier circuit 2. A series circuit of choke coils 35, 36 and forward direction diodes 35, 37 is inserted between the positive electrode side of the output terminal of the rectifier circuit 2 and one end of a series circuit consisting of a pair of switching elements 7, 8. Another capacitor 38 is inserted between the connection point of diode 35 with choke coil 36 and the connection point of switching elements 7, 8. When the switching element 8 is turned on, a current I flows through a loop composed of the choke coil 34, diode 35, capacitors 33, 38, and switching element 8, and thereby the capacitor 38 is charged. If thereafter the switching element 8 is turned off and the other element 7 is turned on, currents II, III flow through specified loops, and the electric charges are discharged from the capacitor 38. If the capacitance of the capacitor 38 is optimized, change in the inter-end voltage of the capacitor 38 nullifies with turn-on/turn-off of the switching elements 7, 8.

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 and a DC power supply 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. 8 shows an example of a device that can improve the power factor with a simple circuit configuration (see, for example, Japanese Patent Laid-Open No.
315796). In FIG. 8, 1 is an AC power supply, 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. Has been done.

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. However, in this 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 increases and the power loss increases.
However, there is a problem that a large size is required and the cost becomes high.

In view of the above-mentioned problems of the conventional circuit, the power factor can be improved with a simple circuit structure, and at the same time,
A device in which the switching element is as small as possible and the manufacturing cost is low has already been invented (for example, Japanese Patent Application No. 5-266409). In this circuit, as shown in FIG. 9, a series circuit of a pair of capacitors 25 and 26 is connected between the output terminals of the full-wave rectifier circuit 2.
Both ends of the series circuit of 5, 5 are connected to the pair of switching elements 7, 8 through forward diodes 28, 29, respectively.
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 via chokes 31.

Explaining the operation of this conventional circuit, the output voltage of the full-wave rectifier circuit 2 is divided into two by the capacitors 25 and 26, and the choke coil 31 via the switching element 8 and the diode 29 is divided by the divided voltage. An electric current is applied to the choke coil 31, energy is stored in the choke coil 31, 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. 10, and when the switching element 8 is turned off and the diode 14 is turned on, FIG.
1, the capacitor 26, the choke coil 31,
A current flows in the loop of the diode 14, the capacitor 23, and the diode 29. When the switching element 7 is turned on, a current flows in the loop of the capacitor 25, the diode 28, the switching element 7 and the choke coil 31 as shown in FIG. 12, and when the switching element 7 is turned off and the die order 15 is turned on, FIG. A current flows in the loop of the capacitor 25, the diode 28, 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, Switching element 7 and capacitor 1
The combined current of No. 4 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 assuming that the power supply voltage of the AC power supply 1 has the waveform shown in FIG. If the inductance of the choke coil 31 is an appropriate value, the input current of the choke coil 31 will be as shown in FIG.
The choke coil 3 has a waveform as shown in FIG.
If the inductance of 1 is too large, the boosting operation is insufficient and the voltage of the AC power supply 1 cannot be charged up to the peak value due to chopping. In this case, at the time when the voltage of the AC power supply 1 reaches its peak, the diode 28, 29 is 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.

[0011]

However, in the case of the circuit of FIG. 9, there is noise generated from the inverter circuit 3. That is, since the diodes 35 and 36 are turned on and off at a high frequency, a high frequency voltage is generated at the voltage at the points a, b, and c, and when the discharge lamp 19 is longer than the point c, radio noise increases. is there.

In view of the above problems, the present invention can improve the power factor with a simple circuit configuration, and the switching element can be made as small as possible to reduce the manufacturing cost.
Moreover, the noise generated from the inverter circuit can be prevented.

[0013]

The first technical means of the present invention for solving this technical problem is an inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8.
In the discharge lamp lighting device in which the discharge lamp 19 is connected to the AC power source 1 via the full-wave rectifier circuit 2 and the output terminal of the inverter circuit 3 is connected to the capacitor between the output terminals of the full-wave rectifier circuit 2. 33 is connected, and the choke coil 34, the forward diode 35, the choke coil 36, and the forward coil are provided between the positive electrode side of the output terminal of the full-wave rectifier circuit 2 and one end of the series circuit of the pair of switching elements 7 and 8. A series circuit of directional diodes 37 is connected, and a capacitor 38 is connected between the connection point between the diode 35 and the choke coil 36 and the connection point between the pair of switching elements 7 and 8.

A second technical means of the present invention is that in which an inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 is connected to an AC power source 1 via a full-wave rectifier circuit 2, A capacitor 33 is connected between the output terminals of the wave rectifier circuit 2, and a choke coil 34 is provided between the positive side of the output terminal of the full wave rectifier circuit 2 and one end of the series circuit of the pair of switching elements 7 and 8. Forward diode 3
5, a series circuit of a choke coil 36 and a forward diode 37 is connected, and a capacitor 38 is connected between the connection point of the diode 35 and the choke coil 36 and the connection point of the pair of switching elements 7 and 8. The load 45 is connected between both ends of the series circuit of the pair of switching elements 7 and 8.

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 is connected to an AC power source 1 via a full-wave rectifier circuit 2, A capacitor 33 is connected between the output terminals of the wave rectifier circuit 2, and a choke coil 34 is provided between the positive side of the output terminal of the full wave rectifier circuit 2 and one end of the series circuit of the pair of switching elements 7 and 8. Forward diode 3
5, a choke coil 36 and a diode 37 in the forward direction are connected in series, and a capacitor 38 is connected between the connection point between the diode 35 and the choke coil 36 and the connection point between the pair of switching elements 7 and 8. A control circuit 46 for controlling the pair of switching elements 7 and 8 is provided to separately oscillate the inverter circuit 3, and a load 45 is connected between both ends of a series circuit of the pair of switching elements 7 and 8. There is a point in doing so.

[0016]

By properly selecting the capacity of the capacitor 38, the voltage across the capacitor 38 hardly changes due to the high frequencies of the switching elements 7 and 8 turning on and off, and the voltage across the capacitor 38 changes according to the cycle of the AC power supply 1. As a result, the voltage across the capacitor 38 becomes about 1/2 of the voltage across the capacitor 33. Further, since the diode is not included in the output line on the negative side of the full-wave rectifier circuit 2, a high frequency voltage is not generated in the voltage at the point a, and the noise generated from the inverter circuit 3 is prevented.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. As shown in FIG. 1, a capacitor 33 is connected between the output terminals of the full-wave rectifier circuit 2 and the output terminal of the full-wave rectifier circuit 2 is connected. A series circuit of a choke coil 34, a forward diode 35, a choke coil 36 and a forward diode 37 is connected between the positive electrode side and one end of the series circuit of the pair of switching elements 7 and 8, and the diode 35 is connected to the series circuit. A capacitor 38 is connected between the connection point between the choke coil 36 and the choke coil 36 and the connection point between the pair of switching elements 7 and 8.

According to the structure of the above embodiment, when the switching element 8 is turned on, the choke coil 3 shown in FIG.
A current I flows through the loop of 4, the diode 35, the capacitor 38, the switching element 8 and the capacitor 33 to charge the capacitor 38. Turn off the switching element 8,
When the switching element 7 is turned on, the current II flows in the loop of the choke coil 34, the diode 35, the capacitor 38, the diode 14, the capacitor 23, and the capacitor 33 shown in FIG. 2 and the choke coil 3 shown in FIG.
A current III flows in a loop of 6, the diode 37, the switching element 7, and the capacitor 38. The current I is discharged by the current III, and the charge charged in the capacitor 38 is discharged by the current II.

When the switching element 7 is turned off and the switching element 8 is turned on, a current I flows in the loop of the choke coil 34, the diode 35, the capacitor 38, the switching element 8 and the capacitor 33 shown in FIG. The choke coil 36, the diode 37, and
The current IV flows in the loop of the capacitor 23, the diode 15 and the capacitor 38.

When the capacitance of the capacitor 38 is properly selected, the high-frequency switching elements 7 and 8 turn on and off the high frequency, the voltage across the capacitor 38 hardly fluctuates, and the voltage changes according to the cycle of the AC power source 1. The voltage across both ends is about 1/2 of the voltage across capacitor 33. Further, since the diode is not included in the output line on the negative side of the full-wave rectifier circuit 2, no high frequency voltage is generated at the voltage at the point a.

FIG. 4 shows another embodiment in which the choke coil 34 and the choke coil 33 are formed on the same iron core. The other points are the same as those of the embodiment shown in FIG. FIG. 5 shows another embodiment in which a diode 41 and a diode 42 are added to reduce the voltage applied to the diodes 35 and 37. The other points are the same as those of the embodiment shown in FIG.

FIG. 6 shows another embodiment, in which the discharge lamp 19 and the capacitor 21 are eliminated, and a load 45 is connected between both ends of a series circuit of a pair of switching elements 7 and 8, whereby the circuit is connected to a DC power supply device. It is intended to be used as. In other respects, the configuration is similar to that of the embodiment shown in FIG. 5, and a smooth DC voltage from which high frequency components have been removed can be supplied to the load 45.

FIG. 7 shows another embodiment. Instead of the transformer 11 and the resistors 12 and 13, a control circuit 46 for supplying a base current to the pair of switching elements 7 and 8 is provided, and the inverter circuit 3 is controlled by the control circuit 46. It is designed to be separately excited. The other points are the same as those of the embodiment shown in FIG. In the above embodiment, the pair of capacitors 9 and 10 are capacitors having no smoothing function, and the smoothing capacitor 23 is connected in parallel to the series circuit of the pair of DC division capacitors 9 and 10. However, instead of this, The smoothing capacitor 23 may be omitted by providing the pair of DC dividing capacitors 9 and 10 with a smoothing function.

Further, although the bipolar transistors are used as the switching elements 7 and 8 in the above embodiment, the switching elements 7 and 8 are not limited to this, and metal oxide film gate field effect transistors (MOSFETs) and other switching elements are used. The element 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.

[0026]

According to the present invention, the power factor can be improved with a simple circuit configuration, and the switching element 7,
8 can be made as small as possible, the manufacturing cost can be reduced, and the noise generated from the inverter circuit 3 can be prevented.

[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 showing another embodiment.

FIG. 5 is a circuit diagram showing another embodiment.

FIG. 6 is a circuit diagram showing another embodiment.

FIG. 7 is a circuit diagram showing another embodiment.

FIG. 8 is a circuit diagram showing a conventional example.

FIG. 9 is a circuit diagram showing a conventional example.

FIG. 10 is a circuit diagram for explaining the operation.

FIG. 11 is a circuit diagram for explaining the operation.

FIG. 12 is a circuit diagram for explaining the operation.

FIG. 13 is a circuit diagram for explaining the operation.

FIG. 14 is a waveform diagram for explaining the operation.

FIG. 15 is a waveform diagram for explaining the operation.

[Explanation of symbols]

 1 AC power supply 2 Full wave rectifier circuit 3 Inverter circuit 7 Switching circuit 8 Switching circuit 19 Discharge lamp 33 Capacitor 34 Choke coil 35 Capacitor 36 Choke coil 37 Diode 38 Capacitor 45 Load 46 Control circuit

Claims (5)

[Claims] 1. An inverter circuit 3 having a series circuit of a pair of switching elements 7, 8 is connected to an AC power supply 1 via a full-wave rectifier circuit 2, and a discharge lamp 19 is connected to an output terminal of the inverter circuit 3. In the discharge lamp lighting device described above, a capacitor 33 is connected between the output terminals of the full-wave rectifier circuit 2, the positive side of the output terminal of the full-wave rectifier circuit 2 and one end of a series circuit of a pair of switching elements 7 and 8. A series circuit of a choke coil 34, a forward diode 35, a choke coil 36, and a forward diode 37 is connected between and, and a connection point between the diode 35 and the choke coil 36 and the pair of switching elements 7 are connected. , 8 is connected to a connection point of the discharge lamp lighting device. 2. The discharge lamp lighting device according to claim 1, wherein the choke coil 34 and the choke coil 36 are formed on the same iron core. 3. An inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 connected to an AC power source 1 via a full-wave rectifier circuit 2, wherein an output terminal of the full-wave rectifier circuit 2 is connected. , The capacitor 33 is connected, and the choke coil 34, the forward diode 35, and the choke coil 36 are provided between the positive electrode side of the output terminal of the full-wave rectification circuit 2 and one end of the series circuit of the pair of switching elements 7 and 8. And a series circuit of forward-direction diodes 37 are connected, and a capacitor 38 is connected between a connection point between the diode 35 and the choke coil 36 and a connection point between the pair of switching elements 7 and 8, and the pair of A DC power supply device characterized in that a load 45 is connected between both ends of a series circuit of switching elements 7 and 8. 4. An inverter circuit 3 having a series circuit of a pair of switching elements 7 and 8 connected to an AC power source 1 via a full-wave rectifier circuit 2, wherein the output terminals of the full-wave rectifier circuit 2 are connected. , The capacitor 33 is connected, and the choke coil 34, the forward diode 35, and the choke coil 36 are provided between the positive electrode side of the output terminal of the full-wave rectification circuit 2 and one end of the series circuit of the pair of switching elements 7 and 8. And a diode 37 in the forward direction are connected in series, and a capacitor 38 is connected between the connection point between the diode 35 and the choke coil 36 and the connection point between the pair of switching elements 7, 8. A control circuit 46 for controlling the pair of switching elements 7 and 8 to separately excite 3 is provided, and the pair of switching elements 7 and 8 are connected in series. Load across 45
A DC power supply device characterized in that the power supply device is connected. 5. The DC power supply device according to claim 3, wherein the choke coil 34 and the choke coil 33 are formed on the same iron core.