JP2003333852A - Power supply - Google Patents

Abstract

(57) [Problem] To provide a variable output voltage power supply device capable of reducing noise of a reactor with a simple configuration. SOLUTION: A bridge rectifier circuit 6 for full-wave rectifying an AC from an AC power supply 1, a reactor 8 connected between the AC power supply and an AC input terminal of the bridge rectifier circuit, an AC input terminal 6a and an AC input terminal. A capacitor 10 connected to the terminal 6b via a bidirectional switch 9;
7b, a zero-cross detecting means 12, a bidirectional switch driving signal generating means 13, and a bidirectional switch driving means 14. The capacitor 10 is charged / discharged by a resonance current with the reactor 8 by conducting control once every half cycle of the bidirectional switch 9 to form a smooth current waveform with a high power factor, and to reduce output of the reactor while reducing noise of the reactor. It controls the voltage.

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 supplying electric power to devices, systems and the like, and more particularly to a power supply device capable of realizing high power factor and low harmonic distortion.

[0002]

2. Description of the Related Art Conventionally, various types of power supply devices have been proposed which can realize high power factor and low harmonic distortion, for example, there is one disclosed in Japanese Patent Application Laid-Open No. 10-80139.
The configuration and operation will be described below. The power supply device shown in FIG. 4A includes an AC power source 1, a bridge rectifier circuit 6 including four diodes 2 to 5, a capacitor 7a connected to DC output terminals 6c and 6d of the bridge rectifier circuit, 7b
And 15, the AC power supply 1 and the bridge rectifier circuit 6
Between the AC input end 6a of the bridge 8 and the AC input end 6a of the bridge rectifier circuit 6 to which the reactor 8 is connected and the other AC input end 6b of the bridge rectifier circuit 6. Bridge rectifier circuit 1 connected to
8, a short-circuit element 19 connected to the DC output terminal of the bridge rectification circuit 18, a zero-cross detecting means 12 for detecting a zero-cross of the AC power supply 1, the zero-cross detecting means 1
A drive signal generation means 16 for generating a drive signal for the short-circuit element 19 based on the output of 2 and a short-circuit element drive means 17 for driving the short-circuit element 19 based on the signal from the short-circuit element drive signal generation means 16. Reference numeral 11 indicates a load.

The operation of the power supply device configured as described above will be described below. The zero-cross detecting means 12 detects the time when the AC voltage of the AC power supply 1 passes through the zero point, and after this zero point, the drive signal generating means 16 generates a power factor improving pulse, and the power factor improving pulse causes the short-circuit element driving means 17 to operate. The AC power source 1 is short-circuited via the reactor 8 and the bridge rectifier circuit 18 by driving the short-circuit element 19 via the reactor 8 and the bridge rectifier circuit 18 to improve the power factor of the power source, and the noise reducing pulse having an extremely short pulse width after the power factor improving pulse. Is generated from the drive signal generation means 16, the short circuit element 19 is driven by the noise reduction pulse, the AC power supply 1 is short-circuited via the reactor 8 and the bridge rectifier circuit 18, and the vibration of the reactor 8 is canceled to prevent noise. To do.

However, in the conventional power supply device as described above, it is necessary to input a predetermined extremely short noise reduction pulse again in a short time after the power factor correction pulse is turned off, and as a result, a high-speed and high-accuracy drive signal is obtained. The generation unit 16 and the short-circuit element driving unit 17 are required, and the short-circuit element 19 is required to have high responsiveness. Further, since the input position of the noise reduction pulse changes due to the variation of the reactor, there is a problem that high precision with less variation of the reactor is required.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems of the prior art, an object of the present invention is to provide a power supply device which does not require reduction of reactor noise and high accuracy. .

[0006]

In order to solve the above-mentioned problems, a power supply device of the present invention comprises a reactor connected between the AC power supply and an AC input terminal of the bridge rectifier circuit, and the reactor connected to the reactor. In addition, a capacitor connected via a bidirectional switch is provided between the AC input end of the bridge rectifier circuit and the other AC input end of the bridge rectifier circuit.

According to the above power supply device, when the series resonance phenomenon of the reactor and the capacitor occurs and the input current flowing from the AC power supply decreases, the bidirectional switch is turned off. Since the input current that flows after turning off is smoothly connected, the reactor does not vibrate due to a sudden change in current when the bidirectional switch is turned off, and the noise of the reactor can be reduced. In addition, after turning off the bidirectional switch, it is not necessary to input a predetermined pulse again in a short time and turn on the bidirectional switch in consideration of reactor variations, so the reactor can be made highly accurate with little variation. .

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The above-mentioned object of the present invention can be achieved by adopting the constitution described in each claim as an embodiment. Therefore, the constitution of each claim will be described below together with the function of the constitution. At the same time, a detailed description will be added to specific terms that require an explanation among the configurations described in the claims, and the embodiments of the present invention will be described.

The invention according to claim 1 for solving the above-mentioned problems, a bridge rectifier circuit for rectifying AC from an AC power source, a positive DC output terminal of the bridge rectifier circuit, and an AC input of the bridge rectifier circuit. A power supply device having a capacitor connected between the AC input terminal of the bridge rectifier circuit and a negative DC output terminal of the bridge rectifier circuit. A reactor connected between the power source and the AC input end of the bridge rectifier circuit, and between the AC input end of the bridge rectifier circuit to which the reactor is connected and the other AC input end of the bridge rectifier circuit. , A capacitor connected via a bidirectional switch, a zero-cross detection unit for detecting a zero point of the voltage of the AC power supply, and an output based on the output of the zero-cross detection unit. The bidirectional switch driving signal generating means for generating a driving signal of the bidirectional switch, in which a bidirectional switch driving means for driving the bidirectional switch based on a signal of the bidirectional switch driving signal generating means.

With such a configuration, the bidirectional switch is made to conduct with an appropriate phase and conduction width, and while the bidirectional switch is conducting for a certain period or longer, the inductance of the reactor and the capacitance of the capacitor are changed. By selecting the inductance L of the reactor and the capacitance C of the capacitor so that the series resonance current exceeds the peak, noise due to vibration of the reactor can be reduced. Further, after turning off the bidirectional switch, it is not necessary to input an extremely short pulse again in a short time in consideration of variations in the reactor, and the reactor can be made to have little variation and high accuracy.

According to a second aspect of the present invention, the reactor is arranged so that the absolute value of the current flowing through the bidirectional switch decreases in a decreasing direction when the bidirectional switch is turned on after being turned on for a certain period or more. The inductor and the capacitance of the capacitor connected in series to the reactor are set.Since the input current that flows after the bidirectional switch is cut off and the current that flows in the reactor and the capacitor are smoothly connected, there is no sudden change in the reactor Vibration can be suppressed.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. The same components as those of the conventional example will be described with the same reference numerals.

(Embodiment 1) FIG. 1 shows an embodiment of the configuration of a power supply device according to the present invention. The power supply device shown in FIG. 1 includes a bridge rectifier circuit 6 formed of four diodes 2 to 5 and an AC power supply 1. A reactor 8 is connected between the AC power supply 1 and the AC input terminal 6a of the bridge rectifier circuit 6, and a capacitor 10 is connected between the AC input terminals 6a and 6b of the bridge rectifier circuit via a bidirectional switch 9. There is.

A capacitor 7a is provided between the positive DC output terminal 6c of the bridge rectifying circuit 6 and the AC input terminal 6b.
However, a capacitor 7b is connected between the AC input terminal 6b and the negative DC output terminal 6d.

Further, a zero-cross detection means 12 for detecting a zero-cross point of the voltage of the AC power supply 1, and a bidirectional switch drive signal generation means 13 for generating a drive signal for the bidirectional switch 9 based on the output of the zero-cross detection means 12.
And a bidirectional switch drive means 14 for driving the bidirectional switch 9 based on the output of the bidirectional switch drive signal generation means 13.

Hereinafter, referring to FIGS. 2 (a) to 2 (d), FIG.
The operation of the power supply device shown in FIG. Figure 2
(A) and (b) show during the positive half cycle of the AC input voltage Vi, and FIGS. 2 (c) and 2 (d) show during the negative half cycle. In addition, FIGS. 3A and 3B show an AC input voltage Vi of 100 V and a reactor 8 of the power supply device shown in FIG.
2 shows each waveform of the embodiment in which the inductance L is L1 mH, the capacitance C of the capacitor 10 is C1 μF, and the capacitance of each of the capacitors 7a and 7b is C2 μF.

FIG. 3A shows waveforms of the AC input voltage Vi, the current (AC input current) IL flowing through the reactor 8, the DC output voltage Vo, and the drive signal Vg of the bidirectional switch 9, and FIG. ) Indicates respective waveforms of the AC input voltage Vi, the current (AC input current) IL flowing through the reactor 8, the drive signal Vg of the bidirectional switch 9, and the voltage Vc across the capacitor 10.

In the above structure, the bidirectional switch 9 is turned off immediately after the positive AC half cycle zero crossing in the AC input voltage Vi, the voltage of the capacitor 7a is higher than the AC input voltage Vi, and the AC input voltage Vi is equal to the AC input voltage Vi. Since the DC output voltage Vo is higher than the voltage obtained by adding the voltage of the capacitor 7b, the diode 2 is reverse-biased and the input current does not flow. At this time, the capacitor 10 has the voltage Vc1 with the polarity shown in FIG. 2D as a result of being charged and discharged in the previous cycle. The bidirectional switch drive signal generation means 13 after a time Δd from the zero cross point from the negative to the positive of the AC input voltage Vi.
Generates an ON signal for the bidirectional switch 9, and when the bidirectional switch driving means 14 turns on the bidirectional switch 9, a current flows as shown by the arrow in FIG. That is, the reactor 8 and the capacitor 10 are sequentially arranged from the AC power source 1.
Current flows through the capacitor 10, the capacitor 10 is immediately discharged, and Vc1
It is charged to Vc2 with the opposite polarity. After a time Δt from the time when the bidirectional switch 9 is turned on, the bidirectional switch drive signal generation means 13 generates an off signal for the bidirectional switch 9, and when the bidirectional switch drive means 14 turns off the bidirectional switch 9, the capacitor 10 is turned on. While holding the voltage Vc2 at that time, the current flows in order from the AC power supply 1 to the reactor 8, the diode 2, and the capacitor 7a as shown in FIG. 2 (b). Further, a current also flows from the AC power supply 1 to the reactor 8, the diode 2, the load 11, and the capacitor 7b in this order, and eventually becomes zero due to the decrease of the AC input voltage Vi.

Immediately after the negative AC half cycle zero crossing, the AC input voltage Vi has the bidirectional switch 9 turned off, the voltage of the capacitor 7b is higher than the AC input voltage Vi, and the voltage of the AC input voltage Vi and the voltage of the capacitor 7a are changed. Since the DC output voltage Vo is higher than the applied voltage, the diode 3 is reverse biased and the input current does not flow. The bidirectional switch drive signal generation means 13 generates an ON signal of the bidirectional switch 9 after Δd from the positive-negative zero cross point of the AC input voltage Vi, and the bidirectional switch drive means 14 turns on the bidirectional switch 9. Then, a current flows as shown by the arrow in FIG. That is, current sequentially flows from the AC power supply 1 to the capacitor 10 and the reactor 8, and the capacitor 10 is discharged and then charged with a polarity opposite to Vc2. Then, after Δt from the time when the bidirectional switch 9 is turned on, the bidirectional switch drive signal generation means 13 generates an off signal for the bidirectional switch 9, and when the bidirectional switch drive means 14 turns off the bidirectional switch 9, the capacitor is turned off. Reference numeral 10 holds the voltage in a state of being charged to the voltage Vc1, and current flows from the AC power supply 1 to the capacitor 7b, the diode 3 and the reactor 8 in this order as shown in FIG. 2 (d). A current also flows from the AC power supply 1 to the capacitor 7a, the load 11, the diode 3, and the reactor 8 in this order, and eventually becomes zero due to a decrease in the AC input voltage Vi.

As described above, in this embodiment, by turning on the bidirectional switch 9, the input current flows from a position closer to the zero cross of the input voltage than in the conventional example, and a high power factor can be realized.

Further, by increasing the conduction time Δt of the bidirectional switch 9, the amount of magnetic energy stored in the reactor 8 can be increased and the DC output voltage Vo can be increased. Similarly, by decreasing the time Δt, the output voltage V
It is possible to decrease o, and the DC output voltage Vo can be changed by increasing or decreasing the time Δt. As shown in FIGS. 2 (a) and 2 (c), the power supply device of the present invention stores energy in the reactor 8 during the conduction period Δt of the bidirectional switch 9, and is shown in FIGS. As described above, while the bidirectional switch 9 is off, the energy is stored in the capacitor 7a,
It has a so-called pressurizing action that is released to 7b.

Also, due to the series resonance phenomenon between the reactor 8 and the capacitor 9, the AC power supply 1, the reactor 8 and the capacitor 1
By selecting the inductance L of the reactor 8 and the capacitance C of the capacitor 10 so that the current flowing in the short circuit of 0 becomes a series resonance current and exceeds the peak value in the ON period Δt of the bidirectional switch 9, Δt in FIG. The current waveform is as shown in the period, and the input current flowing after Δt is smoothly connected. Therefore, the input current at the time when the bidirectional switch 9 is cut off for a certain period of time or more is turned on as shown in FIG. 4B. The vibration of the reactor 8 can be suppressed and the noise of the reactor can be reduced without drastically changing.

When the bidirectional switch 9 is short-circuited,
The LC series resonance of the reactor 8 and the capacitor 10 makes it possible to suppress the current and facilitate the protection.

[0024]

As described above, according to the power supply device of the present invention, the bidirectional switch is provided between the reactor and the AC input end of the bridge rectifier circuit to which the reactor is connected and the other AC input end of the bridge rectifier circuit. By connecting a capacitor through the bidirectional switch and driving the bidirectional switch for a certain period or longer, and by appropriately selecting the inductance of the reactor and the capacitance of the capacitor, a high power factor of the input current can be realized, and when the bidirectional switch is off. Since the input current is smoothly connected, noise due to reactor vibration can be suppressed.

Further, it becomes possible to employ a relatively low speed and low precision drive signal generating means, a short-circuit element driving means and a bidirectional switch having a low responsiveness, and it is not necessary to have a high accuracy in the variation of the reactor, which results in cost reduction. It can be reduced.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a power supply device according to a first embodiment of the present invention.

FIG. 2 is an operation explanatory diagram of the power supply device according to the first embodiment of the present invention.

FIG. 3 (a) AC input voltage Vi, reactor current IL, DC output voltage Vo of the power supply device according to the first embodiment of the present invention,
And (b) each waveform of the bidirectional switch drive signal Vg. Each waveform of the AC input voltage Vi, the capacitor current Ic, the capacitor voltage Vc, and the bidirectional switch drive signal Vg of the power supply device according to the first embodiment of the present invention. Showing

FIG. 4A is a configuration diagram of a power supply device according to an example of a conventional power supply device. FIG. 4B is a diagram showing a conventional power supply device including an AC input voltage Vi, a reactor current IL, a DC output voltage Vo, and a bidirectional switch drive signal Vg. Diagram showing each waveform

[Explanation of symbols]

1 AC power supply 6 Bridge rectifier circuit 8 reactors 9 bidirectional switch 10 capacitors 12 Zero cross detection means 13 Bidirectional switch drive signal generation means 14 Bidirectional switch driving means

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Yasuhisa Ninomiya             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. (72) Inventor Toruhiro Harada             1006 Kadoma, Kadoma-shi, Osaka Matsushita Electric             Sangyo Co., Ltd. F-term (reference) 5H006 AA02 CA01 CA07 CB01 CC01                       CC02 CC08 DB01 DC05

Claims (2)

[Claims] 1. An AC power supply, a bridge rectifier circuit for rectifying AC from the AC power supply, and a capacitor connected between a positive DC output end of the bridge rectifier circuit and an AC input end of the bridge rectifier circuit. And a capacitor connected between the AC input terminal of the bridge rectifier circuit and the negative DC output terminal of the bridge rectifier circuit, the AC power supply and the AC input of the bridge rectifier circuit. And a reactor connected between the other end and an AC input end of the bridge rectifier circuit to which the reactor is connected and the other AC input end of the bridge rectifier circuit, connected via a bidirectional switch. A capacitor, and zero-cross detection means for detecting the zero point of the voltage of the AC power supply,
Bidirectional switch drive signal generation means for generating a drive signal of the bidirectional switch based on the output of the zero-cross detection means, and bidirectional switch drive for driving the bidirectional switch based on the signal of the bidirectional switch drive signal generation means A power supply device comprising means. 2. The inductance of the reactor and the reactor are connected in series so that the absolute value of the current flowing through the bidirectional switch decreases when the bidirectional switch is turned off after conducting for a certain period or more. 2. The power supply device according to claim 1, wherein the capacitance of the generated capacitor is set.