JPH0588067B2 - - 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.
In some cases, a chopper type smoothing circuit 4 consisting of a chopper circuit 40 and a smoothing capacitor 41 is provided between the two and a chopper type smoothing circuit 4 is provided to obtain a high power factor. Here, the chopper circuit 40 includes an inductance element 42, a switching transistor 43, a control circuit 44 for the transistor 43, and a backflow blocking diode 4.
5, and a high power factor is obtained by turning 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. In the figure, 20 is a capacitor, 21 is an inductance element, and 6 is a load such as a discharge lamp. However, in such a conventional example, although a small and inexpensive inductance element 42 can be used, a control circuit 44 for the transistor 43 that constitutes the chopper circuit 40 is newly required. The drawback is that the configuration is complicated 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 have a simple and inexpensive circuit configuration. The objective is to provide a power supply device that is

[Disclosure of the invention]

(Configuration) FIG. 4 is a block diagram showing the configuration of the present invention, which includes a rectifier circuit 3 for full-wave rectification of the commercial power supply 1, a chopper-type smoothing circuit 4 for smoothing the rectifier circuit 3 output V _DC , and a smoothing circuit. The inverter circuit 5 is driven by four outputs applied to an input terminal 59, and outputs a high frequency voltage _VRF with little low frequency ripple at an output terminal 60. The smoothing circuit 4 is formed using an inductance element 42, a smoothing capacitor 41, a switch element 50 that constitutes the inverter circuit 5, and a reverse current blocking diode 51a, and outputs the output of the rectifier circuit 3 through the inductance element 42. A series circuit of a backflow blocking diode 51a and a smoothing capacitor 41 is connected in parallel with the switch element 50 of the inverter circuit 5, and a series circuit of a reverse current blocking diode 51a and a smoothing capacitor 41 is connected to both ends of the smoothing capacitor 41 of the inverter circuit 5. The input terminal 59 is connected to input the voltage across the smoothing capacitor 41 to the inverter circuit 5, which is charged by the electromagnetic energy accumulated in the inductance element 42 when the switch element 50 is turned on, and is charged when the switch element 50 is turned off. It's like this. In the figure, 6 is a load such as a discharge lamp. Incidentally, when the inverter circuit 5 is formed using a plurality of switch elements, one of them may be used as a chopper switch element of the smoothing circuit 4.

Accordingly, in the present invention, the inductance element 42 and the switch element 50 of the inverter circuit 5
Since the chopper circuit is formed in the chipper circuit, the inductance element 42 for improving the input power factor can be miniaturized, and the switch element 50 of the inverter circuit 5 is used to configure the chopper circuit. There is no need to newly provide a switch means (switch element and its control circuit) constituting the circuit, and this has the effect of simplifying the circuit configuration and reducing the cost. Note that since a DC voltage with less low frequency ripple is applied to the input terminal of the inverter circuit 5, which is the same as when the rectifier circuit 3 output V _DC is smoothed by the smoothing capacitor 41, the inverter circuit 5 output A substantially constant high-frequency voltage V _RF can be obtained as follows.If a discharge lamp is lit with this high-frequency voltage V _RF , the luminous efficiency will be improved by reducing restriking loss, the discharge will be stabilized,
Effects such as reduction in flicker can be obtained. Note that any switch element of the inverter circuit may be used as the switch means of the chopper circuit.

Embodiment 1 FIG. 5 shows an embodiment of the present invention, in which an inverter circuit 5 includes two transistors 50 and 51 as switch elements, diodes 50a and 51a connected in antiparallel to the transistors 50 and 51, 2
capacitors 52, 53 and transistor 5
an output transformer 54 equipped with feedback windings 54c ₁ and 54c ₂ that apply a drive voltage to the bases of 0 and 51;
and resistors 55 to 58, a series circuit of transistors 50 and 51, and capacitors 52 and 53.
are connected in parallel to the input end 59, and the primary winding 54a of the output transformer 54 is connected between the midpoints of both series circuits. On the other hand, the smoothing circuit 4 includes an inductance element 42, a transistor 50 of the inverter circuit 5, and a diode 5.
1a and a smoothing capacitor 41,
A switch that applies the output V _DC of the rectifier circuit 3 to one transistor 50 via an inductance element 42 and connects a smoothing capacitor 41 to an input terminal 59 of the inverter circuit 5, forming a chopper circuit of the smoothing circuit 4. The means include one transistor 50 of the inverter circuit 5 and an output transformer 54.
The feedback windings 54c ₁ and 54c ₂ of the transistors 54 and 54c 2 are used to form the reverse current blocking means for charging the smoothing capacitor 41. be. In the above embodiment, feedback windings 54c ₁ and 54c ₂ that control the transistors 50 and 51 are wound around the output transformer 54 to make it a self-exciting type, but the transistors 50 and 54 are controlled by an astable multivibrator. It goes without saying that a separately excited type in which 51 is turned on and off alternately may also be used. Further, the capacitor 52 can be omitted.

The operation of the first embodiment will be explained below. 6th
The figure is an operation waveform diagram showing high frequency operation, and the figure a shows the collector-emitter voltage of the transistor 50.
V _CE , b is the collector current of the transistor 50
Ic ₁ , c is the forward current I _D1 of the diode 50a,
d in the figure shows the collector current Ic ₂ of the transistor 51,
The figure e shows the forward current I _D2 of the diode 51a, the figure f shows the current flowing through the inductance element 42, that is, the output current I _DC of the rectifier circuit 3, and the figure g shows the primary winding current In ₁ of the output transformer 54. . FIG. 7 is an operation waveform diagram showing low frequency operation, where a shows the power supply voltage V _AC of the commercial power supply 1, and b shows the rectifier circuit 3.
The figure _{c shows the input current I AC from} the commercial power supply 1, the figure d shows the voltage Vc across the smoothing capacitor 41, and the figure e shows the high frequency voltage _VRF output from the inverter circuit 5. It is something.

Now, when the commercial power supply 1 is input to the rectifier circuit 3 via the filter 2, the rectifier circuit 3 outputs a DC voltage (pulsating voltage) that has been full-wave rectified by the diode bridge, and this DC voltage is smoothed. The capacitor 41 is charged via the inductance element 42 and the diode 51a. The smoothing capacitor 41 is appropriately charged, and the transistor 5 is connected to the smoothing capacitor 41 through the starting resistors 55 and 56.
When base current is supplied to transistors 50 and 51, one of transistors 50 and 51 is turned on and the other is turned off. Next, the capacitors 52 and 53, the primary winding 54a and the secondary winding 54 of the output transformer 54
b. The oscillating circuit formed by the load 6 induces a voltage in the feedback windings 54c ₁ and 54c ₂ of the output transformer 54 to reverse the on/off state of the transistors 50 and 51, and the transistors 50 and 51 are alternately turned on and off. Repeat. Periods t ₁ and t ₂ in FIG. 6 indicate periods in which the transistor 51 is on and the transistor 50 is off, and a period t ₂ is the period in which the transistor 51 is on and the transistor 50 is off.
0 indicates a period in which the transistor 51 is on and the transistor 51 is off. Here, when an oscillating current flows through the oscillating circuit and a current In ₁ flows through the primary winding 54a of the output transformer 54, this current In ₁ is divided into transistors 50, 51, diodes 50a, 51a, and flows into the load. A current of In ₁ ×n ₁ /n ₂ (where n ₁ /n ₂ is the winding ratio between the primary winding 54a and the secondary winding 54b) flows through the coil 6. Note that the figure shows operating waveforms when the switching frequencies of the transistors 50 and 51 are set higher than the natural oscillation frequency of the oscillation circuit, and the current i _o1 has a delayed phase. by the way,
During the period _t2 in which the transistor 50 is on,
A shunt current I′c ₁ of the current In ₁ is applied to the transistor 50;
A composite current Ic ₁ with the current I _DC flowing from the rectifier circuit 3 through the inductance element 42 flows. At this time,
Electromagnetic energy due to the current I _DC flowing through the inductance element 42 is accumulated. Then the period
When the transistor 50 is turned off at t ₂ , the inductance element 42 is turned off when the transistor 50 is turned on.
The electromagnetic energy stored in the diode 51
The electromagnetic energy is discharged to the smoothing capacitor 41 via the diode bridge of the rectifier circuit 3, and the smoothing capacitor 41 is charged with the electromagnetic energy. In this case, the current I _D2 flowing through the diode 51a becomes a composite current of the shunt current I' _D2 of the current In ₁ and the output current I _DC of the rectifier circuit 3. However, the imaginary line portions in FIGS. 6b, e, and f illustrate fluctuations during a low frequency half cycle (fluctuations due to low frequency ripples). As described above, in the first embodiment, the transistor 50 of the inverter circuit 5, the diode 51a, and the inductance element 42 constitute a chopper circuit, and the switch element of the inverter circuit 5, its control circuit, and the diode Since the chopper circuit for improving the input power factor is formed by using the smoothing circuit 4, the circuit configuration of the smoothing circuit 4 is simplified, and an inexpensive power supply device can be provided.

Embodiment 2 FIGS. 8 and 9 show other embodiments of the present invention, in which the inverter circuit 5a is a transistor 7.
1 to 74, diodes 71a to 74a connected in antiparallel to each transistor 71 to 74, and a control circuit 75 consisting of an astable multivibrator that controls the transistors 71 to 74, and a series circuit of transistors 71 and 72. A load 6 consisting of a choke coil 76, a capacitor 77, and a discharge lamp 78 is connected between the midpoint of the inverter and the series circuit of transistors 73 and 74, forming a so-called full bridge inverter. However, the control circuit 75 includes transistors 79 to 79 as shown in FIG.
82 and pulse transformers 83 and 84, ab is a power supply terminal, cc', dd', ee', ff' are control terminals that output control signals for each transistor 71 to 74, and a control circuit 75 Transistors 71, 72 and transistors 73, 74 are alternately turned on and off by control signals output from the transistors 71 and 73, and transistors 71 and 73 are switched in opposite phases to each other. on the other hand,
The smoothing circuit 4a is composed of an inductance element 42, a transistor 71 of the inverter circuit 5a, a diode 72a, and a smoothing capacitor 41, and applies the output of the rectifier circuit 3 to the transistor 71 via the inductance element 42. The smoothing capacitor 41 is charged via the diode 72a with the electromagnetic energy accumulated in the inductance element 42 when turned on, and the voltage across the smoothing capacitor 41 is applied to the input terminals 59 and 60 of the inverter circuit 5a. It's summery. Note that the operation is the same as in the first embodiment, so a description thereof will be omitted. Furthermore, although a step-up chopper circuit is shown in the embodiment, it goes without saying that a step-down chopper circuit may also be used.

Embodiment 3 FIGS. 10 and 11 show still another embodiment of the present invention, in which an inverter circuit 5b includes a transistor 85 connected in antiparallel with a diode 85a, a control circuit 86 for the transistor 85, and a discharge circuit 5b. The control circuit 86 is composed of an output transformer 87 having a filament winding 87c that heats the filament of the electric lamp 78, and a capacitor 88. The control circuit 86 includes transistors 89 to 91 and a pulse transformer 92.
It is formed using This control circuit 86 operates as an astable multivibrator with the output of the rectifier circuit 3 applied to the power supply terminal ab via the resistor 93, and outputs a control signal for the transistor 85 to the control terminal cc' to operate the transistor 85 at a predetermined frequency. It's starting to turn on and off. The smoothing circuit 4b is composed of a transformer 94, a transistor 85 of the inverter circuit 5c, a control circuit 86, a diode 95, and a smoothing capacitor 41, and the output of the rectifier circuit 3 is the primary winding 94a of the transformer 94, which is an inductance element. The output from the secondary winding 94b of the transformer 94 is rectified by the diode 95 to charge the capacitor 41.

The operation of the third embodiment will be explained below. 1st
Figure 2 shows the operating waveforms of each part, and Figure a shows the collector-emitter voltage V _CE of the transistor 85,
The figure b shows the collector current Ic of the transistor 85, the figure c shows the current I _L flowing through the primary winding 94a of the transformer 94, and the figure d shows the current I _D2 flowing through the diode 95, and t ₁ , t ₃ indicates the on period of the transistor 85, and _t2 indicates the off period of the transistor 85. Note that the collector current Ic is a current Ic ₁ ' flowing through the oscillating circuit consisting of the primary winding 87a of the output transformer 87 and the capacitor 88, and the primary winding 9 of the transformer 94.
It is a composite current with the current I _L flowing through 4a,
The current I _D1 flowing through the diode 85a has a polarity opposite to that of the collector current Ic.

Now, when the output of the rectifier circuit 3 is applied to the control circuit 86 via the resistor 93, the control circuit 86 operates in oscillation, and the transistor 85 is turned on and off.
1 of the output transformer 87 from the smoothing capacitor 41
An oscillating current flows through the secondary winding 87a, a high frequency voltage _VRF is output to the secondary winding 87b and the filament winding 87c, and the preheating discharge lamp 78 is lit at high frequency. Here, the smoothing capacitor 41 is charged in the following manner. That is, during period t ₁ when the transistor 85 is on, in addition to the current I'c ₁ flowing through the oscillating circuit, a current I _L also flows through the primary winding 94a of the transformer 94, and the primary winding 94a electromagnetic energy is stored in Next, during period _t1 when transistor 85 is off, electromagnetic energy is accumulated in primary winding 94a. Then transistor 85 turned off
During period _t2 , the electromagnetic energy accumulated in the primary winding 94a is transferred to the electromagnetically coupled secondary winding 9.
4b, and the smoothing capacitor 41 is charged with the current I _D2 obtained by rectifying the output of the secondary winding 94b with the diode 95. in this case,
Similar to the first and second embodiments, the transistor 85 and the control circuit 86 serve as the switching means constituting the chopper circuit of the smoothing circuit 4b, which has the effect of simplifying the circuit configuration and reducing the cost. ing. If the primary winding 94a of the transformer 94 is wound with the opposite polarity to that shown in FIG. 12, the smoothing capacitor 41 will be charged by the output of the secondary winding 94b when the transistor 85 is turned on. It turns out.

Embodiment 4 FIG. 13 shows still another embodiment of the present invention, in which the inverter circuit 5c has a chiyoke coil 10.
0, transistors 101 and 102, an output transformer 103, and a resonance capacitor 104, forming a so-called push-pull type inverter. . The smoothing circuit 4c is an inductance element 4
2. The inverter circuit 5c is composed of a transistor 101, a diode 105, and a smoothing capacitor 41, forming a chopper-type smoothing circuit as in the previous embodiment. The accumulated electromagnetic energy is transferred to diode 1.
05 to charge the smoothing capacitor 41. Note that a diode 106 shown by an imaginary line in the figure may be provided.

〔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 series circuit of an inductance element and a switch element connected between the DC output terminals of the rectifier circuit, and a series circuit for turning on the switch element. a chopper-type smoothing circuit that includes a series circuit of a backflow blocking diode and a smoothing capacitor that discharges the electromagnetic energy accumulated in the inductance element when the switch element is turned off, and converts DC input into a predetermined DC output; In a power supply device equipped with an inverter circuit connected to both ends of a capacitor for converting DC input into AC output by the on/off operation of a switch element, the switch element of the chopper type smoothing circuit is commonly used as the switch element of the inverter circuit. Since it is equipped with a chopper-type smoothing circuit that converts DC input into a specified DC output, the inductance element used to improve the input power factor can be made smaller. Since it is commonly used as a switch element in the inverter circuit, the number of parts is reduced, the circuit configuration is simplified, and the cost can be reduced.

[Brief explanation of the drawing]

1 to 3 are circuit diagrams of a conventional example, FIG. 4 is a main block circuit diagram showing the configuration of the present invention, FIG. 5 is a circuit diagram showing an embodiment of the same, and FIGS. 8 is a circuit diagram of another embodiment, FIG. 9 is a main circuit diagram of the same as above, FIG. 10 is a circuit diagram of still another embodiment, and FIG. 11 is a circuit diagram of another embodiment. Main part circuit diagram, Fig. 12 is an operation explanatory diagram of the same as above, Fig. 13
The figure is a circuit diagram of yet another embodiment. 1 is a commercial power supply, 3 is a rectifier circuit, 4 is a smoothing circuit,
5 is an inverter circuit, 6 is a load, 41 is a smoothing capacitor, 42 is an inductance element 51a which is a reverse blocking diode, and 50 is a switch element.

Claims (1)

[Scope of Claims] 1. An AC power supply, a rectifier circuit that rectifies the AC power supply voltage, a series circuit of an inductance element and a switch element connected between the DC output terminals of the rectifier circuit, and a series circuit that a chopper-type smoothing circuit that includes a series circuit of a backflow blocking diode and a smoothing capacitor that discharges the electromagnetic energy accumulated in the inductance element when the switch element is turned off, and converts DC input into a predetermined DC output; In a power supply device equipped with an inverter circuit that is connected to both ends of a capacitor for converting DC input into AC output by the on/off operation of a switch element, the switch element of the chopper type smoothing circuit is shared as the switch element of the inverter circuit. Features a power supply device. 2. In a power supply device in which the inverter circuit includes a series circuit of two switch elements connected in antiparallel to each other and turned on and off alternately, the DC output terminal of the rectifier circuit is connected to the DC output terminal of the rectifier circuit through an inductance element. A series circuit of a diode and a smoothing capacitor connected in parallel with the other switch element is connected to both ends of one switch element, and the above inverter circuit is connected to both ends of the smoothing capacitor. 2. The power supply device according to claim 1, wherein the input end of the power supply device is connected to the input end of the power supply device.