JPH0736699B2 - Power supply - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a power supply device in which an AC power supply is rectified and smoothed.

[Background technology]

As shown in FIG. 1, the conventional power supply device rectifies an AC power supply (1) with a full-wave rectifier (2) and connects it to a smoothing circuit composed of a smoothing capacitor C ₀ and a load (3) via an inductance L _1. Was. The voltage-current waveform of each part in the steady state of this circuit is as shown in FIGS. 2 (a) to (c), and the input current is
Is a delay power factor due to the inductance L ₁ as shown in FIG. 2 (c). As a result, the power factor cannot be improved simply by increasing the inductance value of the inductance L ₁ and lengthening the current conduction period (t ₅ −t ₂ ). Inductance
When L ₁ is not present, the power factor becomes low, and when the inductance L ₁ is connected to improve the power factor, the shape of the inductance L ₁ becomes considerably large, and there is a limit in improving the power factor.

Next, FIG. 3 shows a power supply device of a phase-advancing current / phase-delaying current integrated input system, in which an AC power supply (1) is connected to a full-wave rectifier (2) via an inductance L ₁ for phase-delaying current. It is connected to the full-wave rectifier (2) 'through the capacitor C ₁ for the phase-advancing current, and the outputs of the full-wave rectifiers (2) and (2)' are connected to the smoothing capacitor C ₀ and the load (3). Yes, the voltage / current waveform of each part in the steady state is as shown in FIGS. 4 (a) to (e). The input current i _S of this circuit is improved by synthesizing the lagging power factor current i _L due to the inductance L ₁ and the leading power factor current i _C due to the capacitor C ₁ . However, it has a drawback that the structure becomes complicated.

[Object of the Invention]

An object of the present invention is to improve the power factor with a simple circuit configuration.

[Disclosure of Invention]

Example In FIG. 5, (1) is an AC power supply, (2) is a full-wave rectifier, C ₀ is a smoothing capacitor, and (3) is a load to form a smoothing circuit. L ₁ is an inductance, the diode D is connected in series, and the capacitor C ₁ is connected in parallel to the series circuit of this inductance L ₁ and the diode D.

Operation FIG. 6 (a) ~ (e) in each unit voltage and current waveforms of the embodiment of FIG. 5, in the preceding period (time t ₂ previously), the capacitor C ₁
Of the voltage v _{C 1 of −} is charged to −V _{C 1} . | v _S | =-
At time t ₂ when V _{C 1} + V ₀ is reached, the phase-advancing current i _C flows through the capacitor C ₁ and the smoothing capacitor C ₀ . | v _S | =
At time t ₃ when V ₀ is reached, in addition to the advanced current i _C , the delayed current i _L flows through the inductance L ₁ and the smoothing capacitor C ₀ .
| v _S | −V ₀ becomes the maximum, at time t ₄ the phase advance current i that has been flowing through capacitor C ₁ and smoothing capacitor C ₀ until now
_C flows in the opposite direction. The input current i _S becomes zero at time t ₆ when the sum of the advanced current i _C and the delayed current i _L becomes zero. Current i _C
And i _L oscillate in the closed circuit of the inductance L ₁ and the capacitor C ₁ , and then at time t ₇ when the current becomes zero, the capacitor C ₁
The voltage v _{C 1} of V is returned to a negative value −V _C and the oscillation is stopped by the diode. It becomes substantially the same operation as the conventional example of I connexion Figure 3 the above operation, the flow combined current of the leading phase current i _C and the delayed phase current i _L is the input current i _S, the circuit with the input power factor is improved Simpler configuration.

〔The invention's effect〕

As described above, the present invention provides an inductance inserted between a rectifying circuit and a smoothing capacitor, a diode inserted between this inductance and the smoothing capacitor with the smoothing capacitor side as a cathode, and a series circuit of the diode and the inductance. Since there is a capacitor connected in parallel at both ends of the, the input current is a combination of the leading power factor current due to the capacitor and the lagging power factor current due to the inductance, which lengthens the period during which the current flows in the smoothing capacitor. Therefore, the power factor can be improved. Also, by inserting a diode between the inductance and the smoothing capacitor with the smoothing capacitor side as the cathode, it is possible to prevent the closed circuit consisting of the inductance and the capacitor from vibrating, and to reduce the input current with a simple configuration. It is possible to improve the power factor by combining the current of the advanced power factor and the current of the delayed power factor. Furthermore, by connecting a capacitor in parallel to both ends of the series circuit of the diode and the inductance, the energy stored in the inductance can make the voltage across the capacitor the maximum negative voltage possible. The time point at which the current starts to flow can be advanced, and thus the power factor can be improved satisfactorily.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an example of a conventional power supply device, FIG. 2 is a voltage / current waveform diagram of a main part of the same as above, FIG. 3 is a circuit diagram of another example of the conventional power supply device, and FIG. Waveform diagram, FIG. 5 is a circuit diagram of an embodiment of the present invention, and FIG. 6 is a voltage / current waveform diagram of an essential part of the same. (1) ... AC power supply, (2) ... Full wave rectifier, (3) ...
… Load, C ₀ …… Smoothing capacitor, L ₁ …… Inductance, D ₁ …… Diode, C ₁ …… Capacitor.

Claims (1)

[Claims] 1. A rectifying circuit for rectifying an AC power supply, a smoothing capacitor for smoothing a rectified output, an inductance inserted between the rectifying circuit and the smoothing capacitor, and a smoothing capacitor side between the inductance and the smoothing capacitor. A power supply device comprising a diode inserted as a cathode and a capacitor connected in parallel at both ends of a series circuit of the diode and the inductance.