JPH0588068B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a power supply device that receives a commercial power source as an input and outputs a high frequency voltage with little low frequency ripple.

[Background technology]

Conventionally, this type of power supply device used for a discharge lamp lighting device, etc., as shown in FIG. A DC voltage obtained by smoothing the current voltage with a smoothing capacitor 41 is applied to the power input terminal of the inverter circuit 5 for high frequency generation, and the inverter circuit 5 is driven by the smoothed DC voltage, and the load 6 (for example, a discharge lamp) is It was designed to supply a nearly constant high-frequency voltage to the However, in such a conventional example, since the smoothing capacitor 41 with a large capacity is connected in parallel to the output terminal of the rectifier circuit 3, a capacitive load is connected as seen from the power supply side. However, the disadvantage was that the input power factor deteriorated. Therefore, in order to improve the input power factor, an inductance element 7 was inserted in series between the output terminal of the rectifier circuit 3 and the smoothing capacitor 41 as shown in FIG. Since it is necessary to use one for frequency use, the disadvantage is that it becomes large in size and expensive. Therefore, as shown in FIG. 3, a rectifier circuit 3 that full-wave rectifies the commercial power supply 1 inputted through a filter 2, and an inverter circuit 5 that receives DC voltage as input and generates a high-frequency voltage.
A chopper type smoothing circuit 4' consisting of a chopper circuit 40 and a smoothing capacitor 41 is provided between the
There was one that was designed to obtain a high power factor. Here,
The chopper circuit 40 includes an inductance element 42,
It is formed by a switching transistor 43, a control circuit 44 for the transistor 43, and a reverse current blocking diode 45, and turns on and off the transistor 43 under the condition that the voltage across the smoothing capacitor 41 is higher than the commercial power supply voltage to achieve high power output. I'm starting to get a higher rate. In the figure, 20 is a capacitor, and 21 is an inductance element.

FIG. 4 is an operation waveform diagram showing high frequency operation, in which a shows the output current I DC of the rectifier circuit 3, and b shows the output current I _DC of the rectifier circuit 3.
is the collector-emitter voltage of transistor 43
V _CE , c in the figure is the collector current of transistor 43
It shows IC. FIG. 5 is an operation waveform diagram showing low frequency operation, and a in the figure shows the power supply voltage of the commercial power supply 1.
V _AC , b in the same figure is the output power supply I _DC of the rectifier circuit 3, c in the same figure
indicates the input current I _AC from the commercial power supply 1.

Currently, the transistor 43 of the chopper circuit 40 is turned on and off at a relatively high frequency set in the control circuit 44.
Electromagnetic energy is stored in the inductance element 42 during _{the t1} period when the transistor 43 is turned on, and the smoothing capacitor is charged with this stored electromagnetic energy via the diode 45 during the _t2 period when the transistor 43 is turned off. There is. However, in such a conventional example, although the input power factor can be improved by using a small and inexpensive high-frequency inductance element 42, the control circuit of the transistor 43 constituting the chopper circuit 40 44 is newly required, and the circuit configuration becomes complicated and expensive. In addition, since the output current I _DC of the rectifier circuit becomes a current with large ripple as shown in Fig. 4a and Fig. 5b, there is a problem that the noise flowing back to the commercial power supply 1 increases, and it is necessary to prevent this. The disadvantage is that the filter 2 for this purpose is large and expensive.

[Purpose of the invention]

The present invention has been made in view of the above points, and its purpose is to be able to output a substantially constant high frequency voltage without worsening the input power factor, and to reduce noise flowing back into the commercial power supply. It is an object of the present invention to provide a power supply device which can be reduced in number, has a simple circuit configuration, and is inexpensive.

[Disclosure of the invention]

(Basic Configuration) FIG. 6 shows a schematic configuration that is the basis of the present invention.
A series circuit consisting of an AC power supply (commercial power supply) 1, a rectifier circuit 3 that rectifies this AC power supply voltage, an inductance element 42 and a switch element 50 connected between the serial output terminals of this rectifier circuit 3, and a switch. When the element 50 is turned on, the inductance element 42
A chopper-type smoothing circuit that converts DC input into a predetermined DC output is equipped with a series circuit consisting of a backflow blocking diode 45 that discharges the electromagnetic energy accumulated in the switch element 50 when the switch element 50 is turned off, and a smoothing capacitor 41; This is a power supply device comprising an inverter circuit 5 connected to both ends of a capacitor 41 and converting DC input into AC output by the on/off operation of a switch element 50, in which the switch element 50 of the chopper type smoothing circuit is used as the switch element of the inverter circuit 5. It is shared as 50.

Since the inductance element 42 and the switch element 50 of the inverter circuit 5 form a chopper circuit, the inductance element 42 for improving the input power factor can be made smaller, and the switch element 50 of the inverter circuit 5 can be made smaller. Since the chopper circuit is configured by reusing the chipper circuit, there is no need to newly provide a switch means (switch element and its control circuit) that makes up the chopper circuit, which has the effect of simplifying the circuit configuration and reducing the cost. are doing. In addition, at the input end of the inverter circuit 5, a smoothing capacitor 41 is connected to the rectifier circuit 3 output V _DC .
Since a DC voltage with less low frequency ripple is applied, which is the same as when smoothed by the inverter circuit 5,
A substantially constant high-frequency voltage V _RF is obtained as an output, and lighting a discharge lamp with this high-frequency voltage V _RF improves luminous efficiency by reducing restriking loss, stabilizes discharge, and reduces flickering. Effects such as reduction can be obtained. Note that any switch element in the inverter circuit 5 may be used as the switch element constituting the chopper circuit.

Embodiment 1 FIG. 8 shows an embodiment of the present invention, in which an inverter circuit 5 is composed of a choke coil 61, transistors 62, 3, an output transformer 64, a capacitor 65, and starting resistors 66, 67. The transistors 62 and 63 are connected to the feedback winding 64 of the output transformer 64.
The center-tapped primary winding 64a of the output transformer 64 is turned on and off alternately by the voltage induced in the output transformer 64.
It self-oscillates at a frequency set by a resonant circuit consisting of a capacitor 65 and a high frequency voltage _VRF output to the secondary winding 64b of the output transformer 64. is lit at high frequency. On the other hand, the chopper type smoothing circuit 4 includes inductance elements 42a and 42b, transistors 62 and 63 whose switch positions of the inverter circuit 5 are opposite in phase, and a diode 45 for blocking reverse current.
a, 45b, and a smoothing capacitor 41, and the rectifier circuit 3 output is connected to an inductance element 42,
42 to the transistors 62 and 63, respectively, so that when the transistor 62 is on, the electromagnetic energy accumulated in both inductance elements 42a and 42b charges the smoothing capacitor 41 when the transistors 62 and 63 are off. It's summery.

The operation of the first embodiment will be explained below. 8th
The figure is an operation waveform diagram showing high-frequency operation, and a in the figure shows the current I _L1 flowing through the inductance element 42a,
The figure b shows the collector-emitter voltage V _CE1 of the transistor 62, the figure c shows the collector current _IC1 of the transistor 62, the figure d shows the current I _L2 flowing through the inductance element 42b, and the figure e shows the collector-emitter voltage of the transistor 63. V _CE2 , f in the figure is the collector current I _C2 of the transistor 63, g in the figure is the rectifier circuit 3
shows the output current I _DC . In the figure, i ₁ and i ₁ ' are currents flowing through the transistors 62 and 63 via inductance elements 42a and 42b, and i ₂ and i ₂ ' are currents flowing through an oscillating circuit consisting of the primary winding 64a of the output transformer 64 and the capacitor 65. transistors 62, 63
This is the current flowing through the FIG. 9 is an operation waveform diagram showing low frequency operation, where a shows the power supply voltage V _AC of the commercial power supply 1, b shows the output current I _DC of the rectifier circuit 3, and c shows the output current from the commercial power supply 1. The input current I _AC is shown.

Now, in the embodiment, the inductance element 42a, the transistor 62, and the diode 45
A first chopper circuit is formed by a, and a second chopper circuit is formed by an inductance element 42b, a transistor 63, and a diode 45b. Here, each chopper circuit is connected to the transistors 62 and 6 of the inverter circuit 5, as in the basic example above.
3 and its control circuit (feedback winding 64c), the circuit structure is simplified and the cost is reduced. Further, when the transistors 62 and 63 are turned on, currents I _L1 and 2 flowing through the inductance elements 42a and 42b
Since the phase of I _L2 is reversed as shown in Figure 8 a and d, the output current I _DC of the rectifier circuit 3, which is a current that is a composite of both currents I _L1 and I _L2 , is as shown in Figure 8. As shown in g, the high frequency ripple of the output current I _DC becomes smaller. Therefore, the high frequency noise flowing back into the commercial power supply 1 is reduced, and the filter 2 for cutting high frequency noise can be made smaller and less expensive. Furthermore, since two chopper circuits are used to charge the smoothing capacitor 41, the capacity of each chopper circuit can be reduced, and the burden on the transistors 62 and 63 can be reduced. There is.

Embodiment 2 FIG. 10 shows another embodiment, in which the inverter circuit 5a includes transistors 71 to 74, diodes 71a to 74a connected in antiparallel to each of the transistors 71 to 74, and transistors 71 to 74.
The control circuit 75 is composed of an astable multivibrator that controls the transistors 71 and 7.
A load 6 consisting of a chiyoke coil 76, a capacitor 77, and a discharge lamp 78 is connected between the middle point of the series circuit of 2 and the series circuit of transistors 73 and 74. Here, the transistors 71 and 72 and the transistors 73 and 74 are turned on and off alternately by a control signal output from the control circuit 75, and the transistors 71 and 73 are switched in opposite phases to each other. ing.
On the other hand, the smoothing circuit 4a includes an inductance element 42
a, 42b, transistors 71, 73 of the inverter circuit 5a, diodes 72a, 74a, and a smoothing capacitor 41. The output of the rectifier circuit 3 is applied to the transistor 71 via the inductance element 42a, and the inductance element 42b is When the transistors 71 and 73 are turned on, the smoothing capacitor 41 is charged with the electromagnetic energy accumulated in both the inductance elements 42a and 42b via the diodes 72a and 74a.
1 is the input terminal 5 of the inverter circuit 5a.
9 and 59.

Since the switch phases of the transistors 71 and 73 constituting the inverter circuit 5a are in opposite phases, the currents I _L1 and I _L2 flowing from the rectifier circuit 3 through the inductance elements 42a and 42b are in opposite phases. Therefore, the output current I _DC of the rectifier circuit 3, which is a current obtained by combining both currents I _L1 and I _L2 , is a current with small high-frequency ripples, as in the first embodiment. Therefore, the high frequency noise flowing back into the commercial power supply 1 is reduced, and the filter 2 can be made smaller.
Furthermore, since the diodes 72a and 74a connected in antiparallel to the transistors 72 and 74 function as backflow blocking, the backflow blocking diodes can be omitted.

Embodiment 3 FIG. 11 shows still another embodiment. In Embodiment 1, inductance elements 42a, 4
2b are provided with electromagnetically coupled secondary windings 42a', 42b', and the secondary windings 42a', 42b' are connected in series, and the outputs of both secondary windings 42a', 42b' are rectified by a diode 54c. By changing the turns ratio of the transformer consisting of inductance elements 42a, 42b and secondary windings 42a', 42b', the amount of charge of the smoothing capacitor 41, i.e. It is possible to change the voltage at both ends. Note that the output of the rectifier circuit 3 may be applied to the input end of the inverter circuit 5 via the reverse current blocking diode 54d. Further, the same applies to Example 1 and Example 2.

〔Effect of the invention〕

As described above, the present invention includes an AC power supply, a rectifier circuit that rectifies the AC power supply voltage, a pair of series circuits comprising an inductance element and a switch element connected between the DC output terminals of the rectifier circuit, and the switch element. A pair of series circuits comprising a backflow blocking diode and a smoothing capacitor, which release the electromagnetic energy accumulated in the inductance element when the element is turned on, when the switch element is turned off, and convert DC input into a predetermined DC output. A power supply device comprising a chopper type smoothing circuit and an inverter circuit connected to both ends of the smoothing capacitor and converting a DC input into an AC output by on/off operation of a switch element, wherein both ends of the pair of chopper type smoothing circuits The switch element is shared as two switch elements in which the switching phases of the plurality of switch elements of the inverter circuit are opposite to each other, and by providing a chopper type smoothing circuit at the front stage of the inverter circuit, the input In a power supply device in which an inductance element for power factor correction is miniaturized, both switch elements of a pair of chopper type smoothing circuits are used as two switch elements in which the switching phases of the plurality of switch elements of the inverter circuit are opposite to each other. Because they are shared, the number of parts is reduced, the circuit configuration can be simplified, and costs can be reduced.Furthermore, the ripple of the output current of the rectifier circuit is reduced, so there is no backflow to the commercial power supply. This has the effect that the noise can be reduced, and the noise removal filter can be made smaller.

[Brief explanation of the drawing]

Figures 1 to 3 are circuit diagrams of conventional examples, respectively.
4 and 5 are operation explanatory diagrams of the conventional example shown in FIG. 3, and FIG. 6 is a block circuit diagram of the basic example of the present invention.
Fig. 7 is a circuit diagram of one embodiment of the present invention, Figs. 8 and 9 are explanatory diagrams of the same operation as above, Fig. 10 is a circuit diagram of another embodiment, and Fig. 11 is a circuit of still another embodiment. It is a diagram. 1 is a commercial power supply, 3 is a rectifier circuit, 4 is a smoothing circuit,
5, 5a are inverter circuits, 41 are smoothing capacitors, 42, 42a, 42b are inductance elements, 50 are switch elements, 62, 63, 71, 7
3 is a transistor which is a switch element.

Claims (1)

[Claims] 1. A pair of series circuits consisting of an AC power supply, a rectifier circuit that rectifies the AC power supply voltage, an inductance element and a switch element connected between the DC output terminals of the rectifier circuit, and a switch element connected to the DC output terminal of the rectifier circuit, and when the switch element is turned on, the inductance a pair of chopper-type smoothing circuits that convert DC input into a predetermined DC output; The power supply device includes an inverter circuit connected to both ends of the smoothing capacitor and converting DC input into AC output by on/off operation of switch elements, wherein both switch elements of the pair of chopper type smoothing circuits are connected to the inverter circuit. A power supply device characterized in that the plurality of switching elements are shared as two switching elements whose phases are opposite to each other.