JPH04133297A - Power supply - Google Patents

Abstract

PURPOSE:To enhance input power factor and prevent rush current from generating by discharging energy accumulated in an inductor by the use of input current of an inverter circuit to the inverter circuit through a diode and capacitor to the rest area of input current. CONSTITUTION:In an inductor (L)1 inserted in series in a loop of current I including the rest area of an inverter circuit B, energy caused by a current I when it is flowed is accumulated. The accumulated energy is discharged at the rest area to a capacitor (C)1 through a diode (D)2 from the inductor (L)1 to charge the capacitor C1. The electric charge accumulated in the capacitor C1 is discharged to the circuit B through a diode D1. In this case, when the electric charge of the capacitor C1 becomes higher that the voltage of pulsative wave between output end X-Y, the electric charge of the capacitor C1 and the power source for the circuit B becomes a partially smooth one. It is thus possible to maintain the power factor of input high and there is no loop which rush current flows, and thereby no rush current flows at the time of start-up of power supply.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply device that smoothes the low voltage portion of a pulsating waveform obtained by rectifying an AC power supply, and is used, for example, in an inverter circuit for lighting a discharge lamp. It is used as a power source.

[Prior art] Conventionally, the pulsating voltage obtained by rectifying the AC power source is partially smoothed,
A circuit system as shown in FIG. 6 has been proposed as a power supply device that increases the input power factor. The AC input voltage Vin of the AC power supply is full-wave rectified by a diode bridge DB, and a capacitor CI, a diode D2, and a capacitor C2 are connected in series to the rectified output terminal as shown. In addition, a diode D3 is connected in parallel with the series circuit of capacitor C1 and diode D2 with the polarity shown, and a diode D is connected in parallel with the series circuit of diode D2 and capacitor C2.
, are connected with the polarity shown. A load 2 is connected to the rectified output end.

Next, an operational waveform diagram of the above circuit is shown in FIG.

In this circuit, diodes D + , D 2 , and D
'Turn off. When the potential of the pulsating waveform shown in FIG. 7(a) is higher than the sum of the charging potentials of the capacitor CC2, the diode D2 is turned on and the capacitors C, C2 are charged. Also, if the potential of the pulsating flow waveform is the capacitor CI or C
When the charging potential is lower than the charging potential of 2, the diodes D, , D
, is turned on, and the capacitor C1 or capacitor C2 is discharged.6 Therefore, the voltage e applied to the load Z is:
As shown in FIG. 7(b), the pulsating current waveform obtained by full-wave rectification of the input voltage Vin has a waveform in which a portion less than half of the peak value is filled in with the charging voltage of the capacitors C+ and C2. In addition, the input current Iin from the AC power supply is shown in Fig. 7 (c
).

Although this circuit has a very simple circuit configuration, it becomes a partial smoothing circuit while maintaining a high input power factor.Moreover, when capacitors C and C2 are discharged, capacitor CC2 is connected in parallel, so the capacitance can be reduced. .

However, in this circuit, when the power is turned on, the capacitor C diode D2 is connected via the diode bridge DB.
, an inrush current flows in the loop of the capacitor C2, and an overcurrent flows in the fuse F and each diode of the diode bridge DB, so there is a problem that a circuit to suppress the current is required.

In addition, as a configuration in which inrush current does not flow in a partial smoothing circuit,
There is a circuit system disclosed in Japanese Unexamined Patent Publication No. 1-160367. This circuit system is shown in FIG. In this circuit, when the switching element 51 is turned on, the electrolytic capacitor 31, inductor 32, and diode 3 are connected from point a of the rectified output.
4. The switching element 51 charges the capacitor 31 through the path of the rectified output point b, and furthermore, the switching element 51
When turned off, the energy stored in the inductor 32 is
It is discharged through a loop of the diode 34, the capacitor 53 or the load 9, and the electrolytic capacitor 31, and the capacitor 31 is charged. However, this current will flow only when the potential of the electrolytic capacitor 31 is lower than the potential of the pulsating waveform obtained by rectifying the AC power source 1.

In this circuit, the power supply of the single-stone inverter is a partially smoothed power supply, and no inrush current flows. are connected in parallel, and the switching element 51 has a current on the inverter side and an electrolytic capacitor 31.
．． There is a problem in that a composite current of the currents flowing through the inductor 32 flows, and the current withstand capacity of the switching element 51 increases. Furthermore, as a fundamentally different point from the circuit of the present invention described later, in the circuit of FIG. 8, the inverter circuit operates even if the electrolytic capacitor 31 and inductor 32 for partial smoothing are removed, but In the circuit, there is no current loop flowing through the inverter circuit, and the inverter circuit also stops working.

Note that as another conventional example of a partial smoothing circuit in which no inrush current flows, there is a circuit system disclosed in Japanese Patent Publication No. 62-62037. This circuit system feeds back high frequency components to the power supply, and no inrush current flows. They store and release energy in an inductor using a current loop with a current rest period, and their configurations are basically different.

[Problem to be solved by the invention] The present invention has been made in view of the above points,
The purpose of this study is to propose a circuit system in which no inrush current flows in a power supply device that has a high input power factor and partially smoothes pulsating voltage.

[Means for Solving the Problems] In the present invention, in order to solve the above problems, the first
At least one switching element (
A diode bridge D is connected between an inverter circuit B including a transistor Q, ) through which an input current I having a rest period flows, and a diode bridge DB that rectifies the AC power supply.
In a power supply device in which a partial smoothing circuit A is interposed to smooth the low output voltage portion of B, the partial smoothing circuit A is connected between the rectified output terminals X and Y of the diode bridge DB so that the polarity is opposite to that of the rectified output. first and second connected in series
diodes D+, D2 and inverter circuit B
and the inductor Ll inserted in series between the inverter circuit B and the inductor L1, and the first and second diodes D, one end of which is connected to the connection point of the inverter circuit B and the inductor L1.
,, an electrolytic capacitor C whose other end is connected to the connection point of D2
It is characterized by comprising: I.

Note that in place of the inverter circuit B, other switching means such as a chopper circuit may be connected.

Furthermore, instead of the diode bridge DB, a half-wave rectifier may be connected.

[Function] In the circuit shown in Fig. 1, the input current of the inverter circuit B is used to store energy in the inductor of the partial smoothing circuit A, and the fact that the input current has a rest section is used. During this rest period, the energy stored in the inductor is released to the capacitor C1 via one diode D2, and the charge charged in the capacitor C1 is released to the inverter circuit B via the other diode D. There is.

[Example] FIG. 1 is a circuit diagram of a first embodiment of the present invention.

The circuit configuration will be explained below. An AC input voltage Vin of an AC power source is full-wave rectified by a diode bridge DB, and an inverter circuit B is connected between its output terminals X and Y via a partial smoothing circuit A.

First, the partial smoothing circuit A consists of diodes D + and D 2 connected in series in opposite directions between the full-wave rectified output terminal X-7 of the diode bridge DB, and the current I of the inverter circuit B.
An inductor L is inserted in series in a loop in which current flows, and energy is stored by a current (2), and the stored energy of the inductor (L) is discharged through a diode D2 during the rest period of the current, thereby charging the inductor (L). It is equipped with a capacitor C1. The charge of this capacitor C1 is
The load can be discharged to the inverter circuit B via the diode D.

Next, inverter circuit B is a single-channel voltage resonance type inverter, and a fluorescent lamp l is connected to the load. A parallel resonant circuit including an inductor L2 and a capacitor C2 is connected to the input end of the inverter circuit B via a switching transistor Q1. A fluorescent lamp 1 is connected to this parallel resonant circuit via an inductor L3, and a capacitor C is connected in parallel between the non-power supply side terminals of the filament of the fluorescent lamp 1. The switching transistor Q is passively controlled by a control circuit B.

A diode D4 is connected in antiparallel to the transistor Q1.

Further, a capacitor C8 is connected in parallel between the output terminal X-7. This capacitor C0 is connected to the output terminal X-Y
A capacitor with a small capacitance (for example, a capacitance of 0.47 μF or less) that is not sufficient to smooth the pulsating flow waveform between
This is for flowing the high frequency current of the inverter circuit B.

The operation of this embodiment will be explained below.

First, if there is no partial smoothing circuit A, there will be a pulsating current waveform between the output terminals It becomes a waveform. In this way, the current flowing through the switching transistor Q has a rest period, and the current I in FIG.
is the composite current of the current flowing through the transistor Q and the current flowing through the diode D4 (see FIG. 2(e)).6 In the present invention, the rest period of this waveform is utilized.

Now, in the circuit of Fig. 1, if there is a partial smoothing circuit A, it is inserted in series in the loop of current I including the rest section of inverter circuit B, as shown in the waveform diagram of Fig. 2 (c). When a current I flows through the inductor L, energy due to the current I is stored. And the current I
During the pause 7, the inductor discharges the stored energy to the capacitor CI via the diode D2, charging the capacitor C+. The charge stored in the capacitor C1 is discharged to the inverter circuit B via the diode D. However, the potential of this capacitor CI is
- When the voltage becomes higher than the voltage of the pulsating waveform of Y, the charge in capacitor C4 is discharged, and as a result, the power supply of inverter circuit B becomes a partially smoothed power supply, and the input power factor maintains a high power factor. do.

Furthermore, since there is no loop through which an inrush current flows in the electrolytic capacitor C1, no inrush current flows when the power is turned on. Further, even though a circuit for partial smoothing is added, the circuit current flowing through the switching transistor Q1 does not increase significantly.

The operating waveforms of each part in the above circuit are shown in Fig. 3. Fig. 3 (a) shows the AC input voltage Vin, Fig. 3 (b) shows the AC input current of 1 inch, and Fig. 3 (c) shows the diode bridge DB.
It shows the voltage VX-y between the output terminals X-Y of .

Next, a second embodiment of the present invention is shown in FIG.

This embodiment is an example in which the present invention is applied to a half-bridge type inverter. At the input terminal of the inverter circuit B, first and second transistors Q, Q2 for switching are connected.
series circuits are connected in parallel. Each transistor Q,
, Q2 are connected in antiparallel with diodes D3°D, respectively. A series resonant circuit consisting of an inductor L2 and a capacitor C3 is connected to one transistor Q via a coupling capacitor C2 for cutting DC components, and the resonant voltage of the capacitor C3 is applied to the fluorescent lamp L. . Each transistor Q, Q2 is alternately controlled on/off by a control circuit B+. transistor Q
, is off and transistor Q2 is on, the capacitor C2 is connected from the output terminal X-Y of the diode bridge DB.
, a current I flows through the fluorescent lamp I, the capacitor C3, the inductor L2, and the transistor Q2. Also, when transistor Q is on and transistor Q2 is off,
Capacitor C2 becomes the power supply, and from this capacitor C2, transistor Q1, inductor L2, and fluorescent lamp! A current flows through the capacitor C1. In the latter case, the current I from the output X-Y of the diode bridge DB will cease.

In this way, this embodiment uses a half-bridge type inverter circuit B, but since the current I flowing through this inverter circuit B is also a current having a rest period, it operates in the same way as the first embodiment. While maintaining the input power factor at a high power factor,
The partial smoothing circuit A can partially smooth the pulsating flow waveform.

The operating waveforms of the third embodiment of the present invention are shown in FIG. 5. In this embodiment, in the half-bridge inverter circuit B shown in FIG. Fluorescent lamp l by controlling the section
The light is dimmable. Figure 5 (a), (b
), in the case of (b) of the same figure, the ON period of the transistor Q2 is narrower than in the case of (a) of the same figure, so the current flowing through the fluorescent lamp r becomes smaller and dimming is possible. In addition, for each case in FIGS. 5(a) and (b),
The current flowing through the transistor Q2 is as shown in Fig. 5 (e
) and (d). *In the case of FIG. 5(d) during light, the peak current is smaller than in the case of FIG. 5(e), so the energy stored in the inductor Ll of FIG. There is also less charge charged in W, which means that the voltage that partially smoothes the current source is lower, and the power supply voltage of the inverter circuit IB is also effectively lowered, making it possible to further dim the fluorescent lamp L. become. In other words, compared to the case where a fluorescent lamp L is dimmed by duty control of a half-bridge inverter circuit using a conventional partially smoothed power supply, even if the control range of the ON period of the switching transistor Q2 is made smaller, ,
It becomes possible to obtain the same level of dimming output.

In addition, in the partial smoothing circuit A, an inductor L is inserted on the output terminal X side of the diode bridge DB, and a capacitor C
I may be connected in parallel with the inductor L1 via the diode D. In that case, contrary to the illustrated embodiment, the diode D becomes the charging diode for the capacitor C0, and the diode D2 becomes the charging diode for the capacitor C0. It becomes the discharge diode of C1.

Moreover, although the inverter circuit B is separately excited controlled by the control circuit B1, it may be automatically controlled.

[Effects of the Invention] According to the present invention, as described above, since energy is stored in the inductor of the partial smoothing means by the input current of the switching means, there is an advantage that the circuit current of the switching means does not increase significantly. In addition, by using the rest period of the input current of the switching means, the tti energy of the inductor in the partial smoothing means is released to the electrolytic capacitor via one diode, and the electric charge charged in the electrolytic capacitor is transferred to the other diode. Since the configuration is such that the current is discharged to the switching means through the power supply, there is an effect that no rush current flows to the electrolytic capacitor when the power is turned on.

Note that it is advantageous to control the energization period and the rest period of the input current of the switching means, since it is possible to control the stored energy of the inductor and the stored charge of the electrolytic capacitor in conjunction with the output control of the switching means.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram of the first embodiment of the present invention, FIG.
4 is a circuit diagram of the second embodiment of the present invention, FIG. 5 is an operating waveform diagram of the third embodiment of the present invention, FIG. 6 is a circuit diagram of the conventional example, and FIG. FIG. 7 is an operating waveform diagram of the same as above, and FIG. 8 is a circuit diagram of another conventional example. A is a partial smoothing circuit, B is an inverter circuit, DB is a diode bridge, DI and D2 are diodes, C3 is a capacitor, and Ll is an inductor.

Claims (1)

[Claims] (1) Partial smoothing means for smoothing the low output voltage portion of the rectifying means is interposed between the switching means including at least one switching element and through which an input current having a rest period flows, and the rectifying means for rectifying the AC power supply. In the power supply device, the partial smoothing means includes first and second diodes connected in series between rectified output ends of the rectifying means so as to have opposite polarity to the rectifying output, a switching means, and a rectifying means. an inductor inserted in series between the switching means and the inductor, one end of which is connected to the connection point between the switching means and the inductor;
A power supply device comprising: an electrolytic capacitor whose other end is connected to a connection point between the first and second diodes.