JPH0716597U - Power supply - Google Patents

Abstract

(57) [Abstract] [Purpose] It is possible to sufficiently suppress low-order harmonic currents, reduce the installation space compared to using a coil, inexpensive, and to resonate with other circuits. Provided is a power supply device that does not have a bad influence. In a power supply device in which a smoothing capacitor C is connected to the output side of a rectifier circuit DB, a current limiting resistor R that limits the charging current to the smoothing capacitor C is connected to the input side of the smoothing capacitor C.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a power supply device that rectifies and smoothes an AC power supply (for example, AC110V) and supplies DC power (for example, DC5V) to a small power (low power consumption) electric device.

[0002]

[Prior art]

 FIG. 3 shows a circuit diagram of an example of a conventional power supply device. In FIG. 3, DB is a full-wave rectifier in which four diodes are connected in a bridge shape, C is a smoothing capacitor provided at the DC output end of the full-wave rectifier DB, and L is provided at the AC input end of the full-wave rectifier DB. It is a coil.

The power supply device as described above rectifies and smoothes an AC power supply and supplies DC power to a low-power electric device (not shown). In the coil L, the charging current to the capacitor C is intermittent. It has a function of suppressing the generation of higher harmonic current due to flowing into FIG. 4 is a waveform diagram of each part of the power supply device of FIG. 3, where the curve B ₁ of FIG. 4A is the output voltage of the full-wave rectifier DB, and the curve B ₂ is the charging voltage of the smoothing capacitor C. 4 (b) shows the consumed current i.

[0004]

[Problems to be solved by the device]

Since the coil impedance Z _L of the coil L for suppressing harmonics becomes higher as the harmonic current becomes higher, the amount of higher harmonic current can be reduced. However, when the coil L is used, there are the following problems. The coil L has a problem that it has a small function of suppressing harmonic currents of a relatively low order (3, 5, 7, ...). That is, assuming that the inductance of the coil L is, for example, L = 1 mH, in the case of the fifth harmonic (5 × 60 Hz = 300 Hz), ωL = 2π × 60 × 5 × 1 × 10 ^-3 ≈1.9Ω, which is extremely small. The value is small, and the ability to suppress low-order harmonic currents is small.

The coil L has a large shape and requires a large installation space. The coil L is expensive. Depending on the power supply structure and system (on the power supply side of the outlet), the coil L may resonate and adversely affect other circuits. Therefore, the purpose of this device is to sufficiently suppress low-order harmonic current, to reduce the installation space compared to using a coil, to be inexpensive, and to resonate with other circuits. It is to provide a power supply device that does not adversely affect the power supply.

[0006]

[Means for Solving the Problems]

 The power supply device of the present invention is characterized in that, in a power supply device in which a smoothing capacitor is connected to the output side of the rectifier circuit, a current limiting resistor that limits the charging current to the smoothing capacitor is connected to the input side of the smoothing capacitor.

[0007]

[Action]

 The harmonic current is generated by the intermittent flow of the charging current to the smoothing capacitor, that is, the intermittent flow of the consumption current, but the current limiting resistor limits the charging current to the smoothing capacitor. As a result, the charging speed of the smoothing capacitor slows down, the period during which the charging current flows through the smoothing capacitor, that is, the period during which the consumption current flows, becomes longer and its peak value becomes smaller. As a result, the consumption current waveform approaches a sine wave, and the harmonic current is suppressed. In this case, since the period during which the consumption current flows is lengthened and the peak value is reduced to improve the waveform so that the consumption current approaches a sine wave, low-order harmonic currents are also sufficiently suppressed. .

[0008]

【Example】

 FIG. 1 shows a circuit diagram of a power supply device according to an embodiment of the present invention. In FIG. 1, DB is a full-wave rectifier in which four diodes are connected in a bridge, C is a smoothing capacitor provided at the direct current output end of the full-wave rectifier DB, and R is provided at the AC input end of the full-wave rectifier DB. It is a current limiting resistor.

The power supply device as described above rectifies and smoothes an AC power supply and supplies DC power to a low-power electric device (not shown), and the current limiting resistor R is a charging current to the capacitor C, that is, It has the function of suppressing the generation of harmonic currents due to intermittent consumption current flow. 2 shows a waveform diagram of each part of the power supply device of FIG. 1. A curve A ₁ of FIG. 2 (a) is the output voltage of the full-wave rectifier DB, and a curve A ₂ is the charging voltage of the smoothing capacitor C. 2 (b) shows the consumed current i.

Here, the function of the current limiting resistance R will be described with reference to FIG. The harmonic current is generated when the charging current to the smoothing capacitor C flows intermittently, and therefore the consumption current i flows intermittently. However, the current limiting resistor R changes the charging current to the smoothing capacitor C. Since the limit is imposed, the charging speed of the smoothing capacitor C becomes slower, the period during which the charging current flows in the smoothing capacitor C becomes longer, and the peak value of the charging current becomes smaller. As a result, the period during which the consumption current i flows (T₁~ T ₂ ) Becomes longer and the peak value becomes smaller, the waveform of the consumption current i approaches a sine wave, and the harmonic current is suppressed.

In this case, since the charging current is limited and the waveform of the consumption current is improved so as to be close to a sine wave, the low-order harmonic current can be sufficiently suppressed. In addition, since the current limiting resistor R is used to suppress the high harmonic current, the installation space can be made smaller than using a coil, the cost is low, and resonance to other circuits is adversely affected. Never.

More specifically, in the circuit of FIG. 1, the output voltage of the full-wave rectifier DB is shown in FIG. 2A because the current limiting resistor R that limits the charging current to the smoothing capacitor C is provided. As described above, it changes compared with the case of the conventional example (see the curve B _{1 in} FIG. 4A). The change in FIG. 2, since the only flowing current consumption i in between times t ₁ ~t _2, i × peak portion of the output voltage of the R component only full-wave rectifier DB is changed to drop. Due to the voltage drop due to the current limiting resistance R, the voltage difference between the output voltage of the full-wave rectifier DB shown by the curve A ₁ and the charging voltage of the smoothing capacitor C shown by the curve A ₂ is small between time t _{1 and} t _2. Therefore, the charging current flowing into the smoothing capacitor C is reduced. For this reason, the supply time of the charging current to the smoothing capacitor C every half cycle of the AC power supply voltage becomes long, and the charging voltage of the smoothing capacitor C is charged to a state equal to the output voltage of the full-wave rectifier DB. It will take more time. Therefore, as shown in FIG. 2, the consumption current i has a lower peak value due to the insertion of the current limiting resistor R and a longer energization period (t _{1 to} t ₂ ), and its waveform is smaller than that of the conventional example. Will approach a sine wave. As a result, the harmonic current is suppressed.

In the embodiment shown in FIG. 1, the current limiting resistor R is provided in the front stage of the full-wave rectifier DB, but it may be provided in the latter stage.

[0014]

[Effect of device]

 According to the power supply device of this invention, since the current limiting resistor for limiting the charging current to the smoothing capacitor is connected to the input side of the smoothing capacitor, the period during which the consumption current flows is made longer and the peak value is made smaller. The current waveform can be improved so that it approaches a sine wave, low-order harmonic currents can be suppressed sufficiently, and the installation space can be reduced compared to using a coil. Therefore, there is no adverse effect of resonance on other circuits.

[Brief description of drawings]

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

FIG. 2 is a waveform diagram showing an operation of the power supply device of FIG.

FIG. 3 is a circuit diagram showing a configuration of an example of a conventional power supply device.

FIG. 4 is a waveform diagram showing an operation of the power supply device of FIG.

[Explanation of symbols]

 DB Full-wave rectifier C Smoothing capacitor R Current limiting resistance

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Creator Masatoshi Kawakawa 47 Umezu Takaunecho, Ukyo-ku, Kyoto City Nissin Electric Co., Ltd.

Claims (1)

[Scope of utility model registration request] 1. A power supply device in which a smoothing capacitor is connected to an output side of a rectifier circuit, wherein a current limiting resistor for limiting a charging current to the smoothing capacitor is connected to an input side of the smoothing capacitor. .