JPS59148565A - Power source device - Google Patents

Abstract

PURPOSE:To improve the input current power factor with a small inductor and a capacitor, to reduce the power source and to increase the efficiency of the power source by connecting a resonance circuit of the inductor and the capacitor in series between a full-wave rectifier and a smoothing capacitor, and multiplying the resonance frequency by the specific magnification of the power source frequency. CONSTITUTION:An inductor L and a capacitor C1 are connected in parallel to form a resonance circuit 4, and connected in series between the full-wave rectifier 2 and a smoothing capacitor C0. When the resonance frequency f1 of the circuit 4 is set to 2f0<f1<6f0, where f0 represents the frequency of the AC power source 1. The input power factor can be improved by accelerating the phase for starting the conduction of the rectifier 2 by the vibration of the resonance circuit of the inductor L and the capacitor C1, thereby obtaining a power source device having small size and high power factor.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a power supply device that rectifies and smoothes alternating current power to supply direct current to a load.

[Background technology]

As shown in Fig. 1, the conventional power supply device rectifies the AC power source (tx) with a full-wave rectifier (2), smoothes it with a smoothing capacitor co via a choke coil L1, and supplies DC to the load (3). was. In the steady state of this power supply device, the voltage and current waveforms of each part are as shown in FIG. 2 (11) to (c). The input current is is delayed by the choke coil L1 and the power factor increases. As a result, it is not possible to expect an improvement in the power factor simply by increasing the no-inductance of the choke coil L1 and lengthening the current conduction period (1-11). Note that if the choke coil L1 is not provided, the power factor will be low, and if the choke coil L1 is connected to improve the power factor, the shape of the choke coil L1 will be considerably large, and there is a limit to the power factor improvement.

[Purpose of the invention]

An object of the present invention is to improve the input current power factor by using a small interfter and a capacitor, and to provide a small and inexpensive power supply device with a high power factor.

[Disclosure of the invention]

(Example) In Figure 3, +1) Fi AC power supply, (2) full wave.

The rectifier 5 (3) is a load, and Co is a smoothing capacitor. Connect in series between. Resonant circuit (
The resonant frequency 11 of 4) is the frequency of the AC power supply (1) /
.

When 2/”6<8<6/.

shall be.

(Operation) Figures 4 (a) to (c) are voltage and current waveform diagrams for each part in Figure 3, where ■9 is the voltage of the AC power supply (1), and lvsl is the voltage turned over to the + side. It is a VR full wave rectifier (
2), the voltage on the DC output side, V, is the voltage across the smoothing capacitor Co, and i@ is the input current from the AC power supply (1).

While the voltage tvs+ is low, the full-wave rectifier (2) does not conduct;
The voltage Vr is the sum of the voltage Vo and the oscillating voltage generated by the resonance of the interfter L and the capacitor C1. When the voltage IVsl becomes high and crosses the voltage vr, the full-wave rectifier (2) becomes conductive and the input current is flows. This current ts is the sum of the current flowing through the intertaffer L and the current flowing through the capacitor CI, and is not a delayed current as in the conventional example, but flows over a wide range.The full-wave rectifier (2) is conductive. During this time, the voltage Vr becomes approximately equal to the voltage 1v-1, and this voltage V is the voltage V. When it becomes smaller than Capacitor C1
Free vibration of occurs. The above operation is repeated, and the smoothing capacitor Co is charged by the input current is, and the load (3
) is supplied with almost direct current.

The input power factor can be improved due to the vibration of the resonant circuit (4). In the absence of the resonant circuit (4), in other words, the capacitor C1, the voltage Vi is equal to the voltage Vr minus the voltage vo in the non-conducting section of the full-wave rectifier (2). Therefore, the point at which the full-wave rectifier (2) starts conducting is at point C in the figure. However, by adding the capacitor Ch, the voltage v
The free-flowing voltage of the resonant circuit (4) is added to the r&''i voltage Vo, and this oscillating voltage is the voltage V.

is lowered relative to the voltage vo, the point where the voltage Vr and lvsl intersect, that is, the point at which the full-wave rectifier (2) starts conducting, is t! It stops further and becomes a point t1 in the figure. Furthermore, after the full-wave rectifier (2) is turned on, the inductor L
In addition to the slow phase current passing through the capacitor C1, the leading phase current flows through the capacitor C1, so that the power factor can be further improved.

As described above, the main reason for the improvement in the input power factor according to the present invention is that the phase in which the full-wave rectifier (2) starts conducting is stopped due to the vibration of the interfter L and capacitor C1. It is closely related to the phase relationship of the oscillating voltage. In other words, depending on the period, phase, etc. of the oscillating mJ voltage, the presence of this oscillation may actually delay the phase at which the full-wave rectifier (2) becomes conductive.From this, as a result of investigating various circuit constants, we found that the resonant circuit It has been found that the effect of improving the power factor can be found by maintaining the relationship between the resonance frequency (4) and the frequency of the AC power source (1) at a certain value. Fifth
The figure shows AC power supply voltage 100V 13 wave number (/Q) 50H
z f, smoothing capacitor C! is 200 μF, capacitor C+ is 1 to 1000 μF, and load (3) is 2000 μF.
fl4゜ (where f is the resonant frequency of the resonant circuit 0, the power factor (PF) for fl-2T[1] was calculated, and the 6th The figure shows an AC power supply voltage of 100V, a frequency (/,) of 50Hz, and a smoothing capacitor Cm of 400V.
μF, capacitor Ct 33~1000μF1in'J
f when the capacitor L is 3mH and the load (4) is 1000
The power factor (PF) for y4° is calculated. Fifth
As can be seen from the figure and Fig. 6, the power factor can be improved when 2/e<1><676, and the best power factor is obtained when f+=4fo, and even when the intafter L is small. It was observed that the power factor was highest in the range of 3fo<fI<5fo.

Above, the capacitor C1 of the resonant circuit (4) is connected to the inductor L
However, as shown in FIG. 7, a capacitor c1 may be connected in parallel to the output of the full-wave rectifier (2). In this case, the resonant circuit (4) is the smoothing capacitor C
o, and the resonant frequency 11 at that time is as follows.

〔Effect of the invention〕

As described above, the present invention connects a resonant circuit consisting of an interfter and a capacitor in series between a full-wave rectifier and a smoothing capacitor, and sets the resonant frequency of the resonant circuit to be higher than twice the power supply frequency, and higher than six times the power supply frequency. Since the input power is low, the input current power factor can be improved with a small intertactor and capacitor, and it has the effect of providing a small power supply device with a high power factor.

[Brief explanation of drawings]

Fig. 1 is a circuit diagram of a conventional power supply device, Fig. 2 is a voltage and current waveform diagram of the main parts of the same as above, Fig. 3 is a circuit diagram of an embodiment of the present invention, and Figs. 4 (a) to ( c) is a voltage waveform diagram of a main part of the same as above, FIGS. 5 and 6 are characteristic diagrams of the above, respectively, and FIG. 7 is a circuit diagram of another embodiment of the present invention. [11... AC power supply, (2)... Full wave rectifier, (3
)...load, (4)...resonant circuit, L...interface, C1...capacitor, C0...smoothing capacitor. L, -J Fig. 4 - Fig. 5: 1 f1 a.

Claims (1)

[Claims] IT) In a power supply device that supplies DC to a load by rectifying AC power with a full-wave rectifier and smoothing it with a smoothing capacitor, a resonant circuit consisting of an interfter and a capacitor is connected in series between the full-wave rectifier and the smoothing capacitor. connecting the resonant circuit, the resonant frequency of the resonant circuit is higher than twice the power supply frequency;
A power supply device characterized in that the power supply is lower than 6 times.