JP2003033009A - Power device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a power device which reduces DC or AC voltage, and is small-sized and inexpensive, along with being high-efficiency and low-loss. SOLUTION: This power device 1 is provided with a switched capacitor voltage reducing circuit portion 5 which receives an AC or DC positive-electrode voltage, and a control circuit portion 7. In the circuit 5, a first changeover switch 47 is turned off and a second changeover switch 49 is turned on, and a first capacitor 43 is discharged to a load 17 via an output terminal 31. Along with it, a part of the discharge current charges a second capacitor 39. Next a first changeover switch 47 is turned on and the second changeover switch 49 is turned off, and the first capacitor 43 is charged, and along with it the second capacitor 39 is discharged. By doing this way, power is supplied to the load 17 from the first capacitor and the second capacitor alternately.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply device for converting a commercial AC current or a DC current as a power supply into a DC current of a predetermined voltage, and more particularly to a DC load for supplying a DC voltage by lowering the power supply voltage. The present invention relates to a power supply device such as an AC adapter.

[0002]

2. Description of the Related Art Generally, when supplying power to a load that consumes DC power using commercial AC power, a transformer is required to lower the commercial AC voltage. Therefore, when using a load that consumes DC power, an AC adapter having a built-in transformer is connected to an outlet of a commercial AC power supply.

For example, L for displaying and illuminating as a load
When using an ED lamp, the LED is a direct current (DC) number V
It is operated by the power supply voltage of the conventional AC power supply (Japan domestic: 100V, US: 11
0V, Europe: 230V, etc.) is required to convert the AC voltage to several V DC, which requires an AC adapter with a built-in transformer.

On the other hand, when an LED is used as the load, A
There is an attempt to manage the LED by directly connecting it to a commercial AC power supply without using a C adapter. An example thereof will be described below with reference to the drawings.

FIG. 9 is a circuit diagram showing an LED lamp device of Conventional Example 1.

In FIG. 9, 2003 is an AC input terminal, 2004 is an AC input terminal, 2002 is a full-wave rectifying diode bridge (BrD1), 2005 is a series resistor (Rp), and 2006 is a constant current element (CRD; Curre).
nt RegulatedDiode), 2007 is L
It is an ED lamp.

Most of the LED lamps 2007 have 2 to 8 LEDs having a VF (forward voltage drop) of about 2 V, which are connected in series. Therefore, the VF is 4 to 16
It becomes V. The leading voltage of the full-wave rectified waveform sent from the diode bridge 2002 is about 140V in the case of Japan with an effective value of 100V.

IF of the LED for obtaining the required emission brightness
Assuming that the (forward current) is about 10 mA, and if there is only one LED, VF is 2 V, so the resistance 2005
And the voltage to be charged by the constant current element 2006 is 14
0V-2V = 138V, 138V × 10mA =
1.38 W becomes heat and is emitted.

On the other hand, the electric power that contributes to the light emission is 2 V × 10 m
A = 0.02W, and the efficiency is 0.02W / (1.38W + 0.02W) = 0.014, which is only 1.4% and almost 99% is released by heat.

FIG. 10 is a circuit diagram showing an LED lamp device of Conventional Example 2.

In FIG. 10, 2105 is a voltage regulator (Vreg1), 2106 is a current limiting resistor (R
c). In addition, in FIG. 10, the same reference numerals as those in FIG. 9 denote the same or corresponding portions.

In the conventional example 2, since the voltage regulator 2105 balances the voltage fluctuation of the full-wave rectified AC waveform, the constant current element CRD in the above-mentioned conventional example 1 is not necessary and the light emission is stable, but it is power efficient. Is basically the same (low efficiency) as the above-mentioned conventional example 1 because of the series regulation of the voltage.

[0013]

As described above, when the conventional AC adapter is used, the transformer and the load device as a whole are expensive and large in size because a transformer is required.

Further, as described above, the prior arts 1 and 2 both have problems of low efficiency and high loss.
This also applies to the case where the predetermined DC voltage is stepped down to a predetermined voltage lower than that.

Therefore, an object of the present invention is to provide a power supply device for stepping down a DC or AC voltage, which has high efficiency and low loss, and is small and inexpensive.

[0016]

In order to solve the above-mentioned problems, the invention according to claim 1 is a power supply device comprising a switched capacitor step-down circuit unit for receiving an AC or DC positive voltage and a control circuit unit. The switched capacitor step-down circuit unit is connected in series and has an ON position and an OF position.
A plurality of first changeover switches which can be switched to the F position, a first capacitor arranged between the first changeover switches, an ON terminal provided between the output terminal of the switched capacitor step-down circuit unit and each first capacitor. A second selector switch that can be switched between a position and an OFF position, and a second switch provided downstream of the output terminal of the switched capacitor step-down circuit unit.
Each of the first and second changeover switches is provided with a capacitor, and the first and second changeover switches are turned on and off by an oscillation signal from the control circuit unit.
The first switching switch is in the OFF position and the second switching switch is in the ON position so that the load is discharged from the first capacitor to the load through the output terminal, and a part of the discharge is performed. Current is stored in the second capacitor, then the first selector switch is turned to the ON position and the second selector switch is turned on.
By storing electricity in the first capacitor and discharging it from the second capacitor at the FF position, electric power is alternately supplied from the first and second capacitors to the load.

According to the first aspect of the present invention, when the first changeover switch is turned on and the second changeover switch is turned off under the control of the control circuit section, each of the first capacitors (C1 to C4) is turned on as shown in FIG. ) Are connected in series,
Electricity is stored by the power from the rectifying diode bridge. On the other hand, the electric power stored in the second capacitor (Cout) is discharged to the load.

Next, the control circuit section turns off the first changeover switch and turns on the second changeover switch.
As a result, as shown in FIG. 5, each first capacitor (C
1 to C4) are discharged to the load. Each first capacitor (C
The second capacitor (Cout) is charged with a voltage that is the difference between the discharge voltage of 1 to C4) and the consumed voltage of the load.

As described above, the first capacitors (C1 to C4)
By alternately accumulating and discharging with the second capacitor (Cout) and the second capacitor (Cout), it is possible to continuously and stably supply a DC current of a predetermined voltage obtained by stepping down an AC or DC voltage to the load.

In particular, according to the power supply device of the present invention, when the commercial AC voltage is stepped down to a DC voltage of a predetermined voltage, the commercial AC current is converted into a DC voltage of several volts without using a conventional transformer. Since it can be supplied to the load by a small amount, it is small and inexpensive.

In addition, the capacitor merely repeats the storage and discharge, and the resistor for reducing the voltage is not provided, so that the efficiency is high and the loss is low.

According to a second aspect of the present invention, in the first aspect of the present invention, the switched capacitor step-down circuit section and the control circuit section are provided on a semiconductor substrate, and the changeover switch is provided on the semiconductor substrate. MO provided in
It is an S-type transistor.

According to a third aspect of the present invention, in the first aspect, the switched capacitor step-down circuit section and the control circuit section are provided on a semiconductor substrate, and the changeover switch is provided on the semiconductor substrate. SC provided in
It is characterized by being R (thyristor).

According to a fourth aspect of the present invention, in the first aspect of the invention, the switched capacitor step-down circuit section and the control circuit section are provided on a semiconductor substrate, and the changeover switch is provided on the semiconductor substrate. IG provided in
It is characterized by being a BT (insulation type bipolar transistor).

According to the inventions described in claims 2 to 4, the same operational effect as the invention described in claim 1 is obtained, and
By providing at least the switched capacitor step-down circuit section and the control circuit section on the semiconductor substrate to form an IC substrate,
Further, the size can be reduced, and the manufacturing cost can be reduced.

The first and second capacitors may be externally attached to obtain a voltage according to the load. In this case, since a capacitor having an arbitrary capacity can be attached or replaced, it is possible to easily obtain a DC voltage as needed.

According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, a plurality of switched capacitor step-down circuit units are provided, and the control circuit unit alternates the switched capacitor step-down circuit units. And the other switched capacitor step-down circuit section is charged while the other switched capacitor step-down circuit section is discharging.

In the invention described in claim 5, claim 1
In addition to the operational effect described in any one of 4 to 4, a plurality of switched capacitor step-down circuit units are provided, and the control circuit unit controls the switching of the switches so that the other unit stores electricity while one is discharging, which further stabilizes the operation. The predetermined voltage can be obtained.

[0029]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to FIGS. FIG. 1 is a circuit diagram showing a first embodiment of a power supply device according to the present invention.

As shown in FIG. 1, the power supply device 1 includes a diode bridge (BrD1) 3 for full-wave rectification, a switched capacitor step-down circuit unit 5, and a control circuit unit 7 for full-wave rectification. The diode bridge 3 obtains a rectified waveform of the power supply voltage, and is connected to the AC input terminals 9 and 11. The AC input voltage is commercial 100V.

The output terminal 13 of the power supply device 1 is the positive output side of the direct current, and the output terminal 15 is the negative side.
A DC current load 17 having a predetermined voltage is connected to these DC output terminals 13 and 15. The load 17 is not particularly limited, but for example, an LED that receives a voltage of several volts
It is a lamp.

The circuit between the full-wave rectifying diode bridge 3 and the switched capacitor step-down circuit section 5 is provided with a capacitor 19, resistors (R1, R2) 21 and 23 for voltage division, and a capacitor 25. , Reference numeral 27 is a GND (ground) line. Here, the resistors 21 and 23 are connected in series to divide the output voltage of the full-wave rectifying diode bridge 3, and the voltage dividing point is connected to the operating power supply input terminal of the control circuit unit 7. The control circuit unit 7 is provided with an input oscillation circuit unit (Osc) and a clock signal control circuit unit, and controls ON / OFF of each changeover switch (described later) of the switched capacitor step-down circuit unit 5. There is.

The input terminal 42 of the switched capacitor step-down circuit section 5 is connected to the positive output terminal from the full-wave rectifier diode bridge 3, and is connected to the direct current output terminal (OUT +) 31 of the switched capacitor step-down circuit section 5. Is connected to the output terminal 13 via the backflow prevention diode 33 and the series regulator 35, and the minus output terminal (OUT−) 37 of the switched capacitor step-down circuit unit 5 is grounded.

On the output side of the switched capacitor step-down circuit unit 5, a second capacitor 39 whose one terminal is grounded is provided between the flow prevention diode 33 and the series regulator 35.
A capacitor 41 whose one terminal is grounded is also provided between the output terminal 5 and the output terminal 13.

In the switched capacitor step-down circuit section 5,
The positive output of the full-wave rectifying diode bridge 3 is input, and the switched capacitor step-down circuit unit 5 is controlled by the control circuit unit 7.
It controls the positive electrode output (voltage) of the direct current supplied to the output terminal 31 in response to the signal from.

As shown in FIG. 2, the switched capacitor step-down circuit section 5 includes four first capacitors (C1 to C4).
43 is externally attached to each mounting part (CAP +, CAP−) 49, 51. Each first capacitor (C1 to C4) 43
, A first changeover switch 47 is connected in series. When the first changeover switch 47 is in the ON position, the first capacitor (C1 to C4) 43 is energized, and when it is in the OFF position, the energization is stopped. ing. A photo MOS relay is used for each first changeover switch 47.

Further, the condenser mounting portion (CAP +, C
A second changeover switch 49 is provided between the AP−) 49, 51 and the output terminals 31, 37. The second changeover switch 49 is energized at the ON position and is stopped at the OFF position. A photo MOS relay is also used for each of the second changeover switches 49.

In the control circuit section 7, the voltage-divided outputs of the resistors 21 and 23 are input to output a predetermined oscillation signal, and
The switched capacitor step-down circuit section 5 receives the clock signal whose duty is controlled according to the current detection signal value by receiving the current detection signal and the oscillation signal in the clock signal control circuit section.
To give to.

For the first changeover switch 47 and the second changeover switch 49, specifically, the MOS type transistor of the circuit shown in FIG. 8A is used, but FIG. 8B is used.
It may be an SCR (thyristor) or an IGBT (insulated bipolar transistor) shown in FIG.

Further, in the present embodiment, the switched capacitor step-down circuit section 5 and the control circuit section 7 are provided on the semiconductor substrate (the one-dot chain line shown by reference numeral 6 in the figure), and the first changeover switch 47 and the first changeover switch 47 are provided. The 2-switch 49 is integrated on the semiconductor substrate 6.

The operation of the switched capacitor step-down circuit section 5 will be described below. First changeover switch 47
As shown in FIG. 3, the ON / OFF switching timing between the second switching switch 49 and the second switching switch 49 is ON when the second switching switch is ON when the first switching switch 47 is OFF.
Therefore, when the second changeover switch 47 is off, the first changeover switch is turned on so that the ON states of the first changeover switch 47 and the second changeover switch 49 are controlled so as not to overlap. The ON time of the first changeover switch 47 is, for example, 4 msec, and the OFF time is controlled to 8 msec.

When the first changeover switch 47 is ON and the second changeover switch 49 is OFF, the first capacitors (C1 to C) connected in series are connected as shown in FIG.
4) 43 becomes the charged state, and each first capacitor (C1 to C1
C4) 43 is stored.

Next, the first changeover switch 47 is turned off.
And the state in which the second changeover switch 49 is ON is as shown in FIG.
, Each of the first capacitors (C
1 to C4) 43, and the first capacitors (C1 to C4) 43 are discharged.

Here, the discharged current is supplied from the output terminal 31 of the switched capacitor step-down circuit unit 5 to the load 17 through the backflow prevention diode 33, but the discharged voltage becomes a voltage higher than that of the load 17. By setting
Due to the voltage difference between the discharge voltage of the first capacitor 43 and the load 17, the second capacitor 39 is charged when the first capacitor 43 is discharged.

Next, the first changeover switch 47 is turned off again.
When it becomes N and the second changeover switch 49 is turned off, the respective first capacitors (C1 to C4) 43 are brought into the state of FIG.
In 39, discharging is performed and the load 17 is supplied with a current of a predetermined voltage.

As described above, the control circuit unit 7 turns on and off the first changeover switch 47 and the second changeover switch 49.
By alternately switching F, it is possible to continuously supply a current of a predetermined voltage to the load 17.

[Experimental Example] In the above-described embodiment, a circuit similar to the circuit shown in FIG. 1 was constructed and an experiment was conducted under the following conditions. The result is shown in FIG. The experimental conditions were as follows.

Power supply voltage: 30 V First capacitors (C1 to C3): Three capacitors were used, and each first capacitor was 100 μF.

Second capacitor (Cout): 100 μF Output load: 40mA constant current The backflow prevention diode 33 was not used.

First and second changeover switches 47, 49
Means that the ON time of the first changeover switch 47 (in other words, the electricity storage period of the first capacitors C1 to C3) is 4 msec, and the ON time of the second changeover switch 49 (in other words, the electricity storage period of the second capacitor (Cout)). Was controlled as 8 msec.

Under the above conditions, the voltage at each elapsed time at the point X shown in FIG. 2 and the point Y shown in FIG. 1 was measured, and the results are shown in FIG. In FIG. 6, X0 indicates the voltage at point X, and Y0 is the voltage at point Y. Further, X1 is a charge period of the first capacitor 43 (in other words, a discharge period of the second capacitor 39), and Y1 is a charge period of the second capacitor 39 (in other words, a discharge period of the first capacitor 43). is there.

As is apparent from the graph shown in FIG. 6, the Y0 waveform has a substantially smooth waveform near a predetermined voltage (about 6 V), and the predetermined voltage can be continuously supplied.

That is, since the second capacitor 39 is discharged during the storage period of the first capacitor 43, a voltage such as Z (indicated by a chain double-dashed line in FIG. 6) that would be generated only by the first capacitor 43. I was able to prevent the fall.

According to the configuration using the switched capacitor step-down circuit section 5 as described above, the commercial power supply voltage is stepped down to a low voltage without using a transformer or an inductor, and a high breakdown voltage switching element is not used. The voltage can be applied to the load 17.

That is, according to this embodiment, the so-called A
The C adapter can be downsized and the cost can be reduced. For example, the power supply device according to the present embodiment can be incorporated in a plug by making it an IC substrate. In addition, it is possible to construct an isolated power supply without using a transformer, which is extremely epoch-making.

Next, a second embodiment of the present invention will be described with reference to FIG. In the embodiment shown in FIG. 7, two switched capacitor step-down circuit units 5 and 5 are provided in parallel, and one switched capacitor step-down circuit unit 5 and the other switched capacitor step-down circuit unit 5 alternately store electricity. And discharge. Other configurations are the same as those of the above-described first embodiment. According to the second embodiment, the output voltage supplied to the load can be made more stable than that of the first embodiment, and a substantially linear constant voltage can be supplied as shown by a chain line W in FIG. You can

The present invention is not limited to the above-described embodiments, but can be variously modified without departing from the spirit of the present invention. For example, in the above-described embodiments, the power supply device for stepping down the commercial AC power supply to the direct current of the predetermined voltage has been described as an example, but the present invention is not limited to this, and the direct current voltage is used as the power supply to convert the direct current to the predetermined voltage. It may be one that reduces the pressure. In this case, do not use the rectifying diode bridge 3,
The positive output terminal of the DC voltage is connected to the input terminal 42 of the switched capacitor step-down circuit unit 5.

[0058]

According to the first aspect of the present invention, the first capacitor (C1 to C4) and the second capacitor (Cout) are alternately charged and discharged repeatedly to generate a direct current of a predetermined voltage. The load can be continuously and stably supplied.

Further, a commercial AC current can be converted into a DC current of several volts and supplied to a load without using a conventional transformer, so that a small and inexpensive power supply device can be provided.

Moreover, the capacitor merely repeats storage and discharge, and no resistor for reducing the voltage is provided, resulting in high efficiency and low loss.

In the inventions described in claims 2 to 4, the same operational effect as the invention described in claim 1 is obtained, and
By providing at least the switched capacitor step-down circuit section and the control circuit section on the semiconductor substrate to form an IC substrate,
Further, the size can be reduced, and the manufacturing cost can be reduced.

According to the invention of claim 5, claim 1
In addition to the operational effect described in any one of 4 to 4, a plurality of switched capacitor step-down circuit units are provided, and the control circuit unit controls the switching of the switches so that the other unit stores electricity while one is discharging, which further stabilizes the operation. The predetermined voltage can be obtained.

[Brief description of drawings]

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

FIG. 2 is an explanatory diagram of an operation principle of the switched capacitor step-down circuit unit in FIG.

FIG. 3 is an explanatory diagram of ON and OFF timings of respective changeover switches.

FIG. 4 is an explanatory view of the operation of the switched capacitor step-down circuit by turning on the first changeover switch and turning off the second changeover switch.

FIG. 5 is an explanatory diagram of an operation of the switched capacitor step-down circuit by turning on the first changeover switch and turning off the second changeover switch.

FIG. 6 is a graph showing a voltage obtained according to the present embodiment.

FIG. 7 is a circuit diagram of a power supply device according to a second embodiment.

FIG. 8 is a circuit diagram showing a specific mode of first and second changeover switches.

FIG. 9 is a circuit diagram showing a conventional device (example 1).

FIG. 10 is a circuit diagram showing a conventional device (example 2).

[Explanation of symbols]

1 power supply 5 Switched capacitor step-down circuit 7 Control circuit section 17 load 39 Second capacitor (Cout) 43 First capacitor (C1 to C4) 47 First changeover switch 49 Second changeover switch

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yoshie Ozaki             2-29-9 Nishi Gotanda Stock Exchange, Shinagawa-ku, Tokyo             Inside Takion F-term (reference) 3K082 AA61 AA62 AA64 AA76 BA00                       BA02 BD04 BD22 BD31 BE01                       CA31                 5G065 AA01 AA08 DA04 HA02 JA02                       KA02 KA05 LA01 MA10 NA01                       NA04 NA08                 5H730 AA15 AS05 BB03 BB81 BB88                       CC01 DD03 DD04 DD05 EE43                       VV01

Claims (5)

[Claims] 1. A power supply device comprising a switched capacitor step-down circuit section for receiving an AC or DC positive voltage and a control circuit section, wherein the switched capacitor step-down circuit section is connected in series and is in an ON position. And a plurality of first changeover switches that can be switched between OFF and OFF positions, a first capacitor arranged between the first changeover switches, and an output terminal of the switched capacitor step-down circuit unit and each first capacitor. A second changeover switch that can be switched between an ON position and an OFF position and a second capacitor provided downstream of the output terminal of the switched capacitor step-down circuit unit are provided, and each of the first and second changeover switches is a control circuit unit. The ON / OFF position can be switched by the oscillation signal from the first switching switch to the OFF position. And turn on the second selector switch
As a position, the load is discharged from the first capacitor to the load through the output terminal, and a part of the discharged current is stored in the second capacitor, and then the first changeover switch is turned on.
Position and the second selector switch in the OFF position to store electricity in the first capacitor and discharge it from the second capacitor, so that
A power supply device characterized by alternately supplying power from a capacitor. 2. The switched capacitor step-down circuit section and the control circuit section are provided on a semiconductor substrate, and the changeover switch is a MOS provided on the semiconductor substrate.
The power supply device according to claim 1, wherein the power supply device is a type transistor. 3. The switched capacitor step-down circuit unit and the control circuit unit are provided on a semiconductor substrate, and the changeover switch is an SCR provided on the semiconductor substrate.
It is a (thyristor), The power supply device of Claim 1 characterized by the above-mentioned. 4. The switched capacitor step-down circuit unit and the control circuit unit are provided on a semiconductor substrate, and the changeover switch is an IGBT provided on the semiconductor substrate.
The power supply device according to claim 1, wherein the power supply device is T (insulation type bipolar transistor). 5. A plurality of switched capacitor step-down circuit sections are provided, and the control circuit section alternately switches the switched capacitor step-down circuit sections so that when one switched capacitor step-down circuit section is discharging, 2. The switched capacitor step-down circuit unit stores electricity.
The power supply device according to any one of to 4.