JPH03256520A - Dc power supply unit - Google Patents

Abstract

PURPOSE:To reduce the harmonic component of an AC input current so as to prevent the occurrence of a high-frequency trouble by respectively connecting the first, second, and third DC output terminals to the rectifier circuit-side terminal of a DC reactor, the intermediate tap of the reactor, and the non-DC reactor-side terminal of a capacitor. CONSTITUTION:The first and second positive-polarity output terminals P1 and P2 are respectively connected to one terminal and intermediate tap of a DC reactor 10 equipped with the intermediate tap and the negative-polarity output terminal N of the circuit is connected to one end of a parallel circuit composed of a capacitor 6 for smoothing, one end of which constituting the other end of the parallel circuit is connected to the other terminal of the reactor 10 and a load 7. Therefore, the harmonic component of an AC input current can be reduced.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a DC power supply device used in a UPS (uninterruptible power supply), a switching power supply, etc. The present invention relates to a DC power supply device equipped with a rectifier circuit.

(Prior Art) FIGS. 7(a) and 7(b) show the circuit configuration of the most typical DC power supply device, and the AC power supply voltage e and current waveform j. In FIG. 7(a), an AC power source 1 is connected to the AC input side of a single-phase bridge rectifier circuit composed of diodes 2 to 5, and a smoothing capacitor 6 is connected to the DC output side of the rectifier circuit. and the load 7 is connected to the capacitor 6
are connected in parallel. In such a configuration, when the AC voltage (power supply voltage) e in FIG. 7(b) is positive and this value exceeds the DC voltage of the capacitor 6, the diodes 2 and 5 become conductive, and the AC voltage e becomes In a negative period,
When this value exceeds the DC voltage of the capacitor 6, the diodes 3 and 4 become conductive, and a current i with a narrow width and a large peak value flows from the AC power supply 1 into the rectifier circuit as shown in Figure 7(b). , and is rectified and supplied to a parallel circuit of capacitor 6 and load 7.

Next, FIG. 8(a) shows the AC power supply 1 in FIG. 7(a).
Another conventional example is shown in which an AC reactor 11 is connected between the AC input side of the rectifier circuit and the AC input side of the rectifier circuit.

Its operation is the same as that shown in FIG. 7, but as shown in FIG. 8(b), the waveform of the power supply current i in this conventional example has a peak value compared to that shown in FIG. 7(b) due to the action of the AC reactor 11. is getting smaller.

Moreover, FIG. 9(a) shows yet another conventional example, and FIG. 7(a) shows another conventional example.
A smoothing DC reactor 12 is connected between the DC output side of the rectifier circuit in a) and the capacitor 6. Its operation is similar to the conventional example shown in FIG. 7, but the waveform of the power supply current i is a square wave alternating current as shown in the figure, as is well known.

(Problem to be Solved by the Invention) In the conventional example described above (Figs. 7 to 9), it is known that the power supply current contains many odd harmonics. In the conventional example, the harmonics contained in the power supply current i are 33% of the fundamental wave, 33% of the 3rd harmonic, 20% of the 5th harmonic, and 14% of the 7th harmonic. As a result, the voltage waveform of the power line is distorted, causing harmonic interference such as causing other equipment connected to the same power line to malfunction or heating up due to harmonic components.

The present invention has been made to solve the above problems,
The purpose is to provide a DC power supply device that reduces harmonic components of AC input current and prevents various harmonic disturbances from occurring.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a rectifier circuit with first and second DC output terminals connected to one polarity of the DC voltage and connected to the other polarity. a third DC output terminal connected to the rectifier circuit side terminal of the DC reactor, and a second DC output terminal connected to the intermediate tap of the DC reactor; The DC output terminal of No. 3 is connected to the non-DC reactor side terminal of the capacitor.

(Function) According to the present invention, when the AC power supply voltage is higher than the DC voltage of the capacitor, the rectifier circuit is connected to the AC power supply.

Current flows between the capacitor and the load through the center tap of the DC reactor. On the other hand, when the power supply voltage is lower than the DC voltage of the capacitor, current flows from the AC power supply through the rectifier circuit and the DC reactor to the capacitor and the load. At this time, for example, if an intermediate tap is provided at 1/2 of the inductance of the DC reactor, the ratio of the current when the power supply voltage is higher than the DC voltage of the capacitor and the current when it is lower becomes approximately 1/2, and the power supply current becomes a step-like waveform and harmonics are reduced.

(Example) The present invention will be described in detail below with reference to the drawings.

First, FIGS. 1 and 2 show a first embodiment of the present invention,
The case where the AC power supply is a single-phase two-wire type is shown.

In Figure 1 (,), the AC power source l is connected to diodes 2 to 5.
It is connected to the alternating current input side of a rectifier circuit constituted by 8 and 9. Further, the first and second positive output terminals P0. The first positive output terminal P□ of P2 is connected to one terminal of the DC reactor 10 with an intermediate tap, and the second positive output terminal P2 is connected to the intermediate tap of the reactor 10, and furthermore, the rectifier The negative output terminal N of the circuit is connected to the other end of a parallel circuit of a smoothing capacitor 6 and a load 7, one end of which is connected to the other terminal of the reactor 10.

In such a configuration, when the power supply voltage e of the AC power supply 1 is positive and the voltage value is higher than the DC voltage value of the capacitor 6, the voltage e from the AC power supply 1 to the diode 8, the terminal P2 . A current 1 shown in FIG. 1(b) flows through the center tap of the reactor 10, the terminal on the capacitor 6 side of the reactor 10, the parallel circuit of the capacitor 6 and load 7, the terminal N, and the diode 5, and the power supply voltage When e is positive and the voltage value is lower than the DC voltage value of the capacitor 6, the voltage from the AC power supply 1 to the diode 2 and the rectifier circuit side terminal of the reactor IO, that is, the terminal P
1. A current flows through the capacitor 6 side terminal of the reactor IO, the parallel circuit of the capacitor 6 and the load 7, the terminal N and the diode 5 as shown in FIG. 1(b).

The values of current and current in this operation mode are determined by the ratio n of the number of turns between the intermediate tap and the terminal on the side of the capacitor 6 to the total number of turns of the reactor 10, that is, the ratio of the inductance. =nX1. bawl. Therefore, by setting this ratio to an appropriate value, the waveform of the power supply current i can be changed as shown in Fig. 1 (b
) becomes a step-like waveform as shown in the positive half-wave period.

The same applies when the power supply voltage e of the AC power supply 1 is negative, and when the absolute value of the power supply voltage is higher than the DC voltage of the capacitor 6,
From AC power supply 1 to diode 9, terminal P2. Reactor 1
A current I flows through the middle tap of 0, the terminal on the capacitor 6 side of the reactor 10, the parallel circuit of the capacitor 6 and load 7, the terminal N and the diode 3, and the absolute value of the power supply voltage is the DC voltage of the capacitor 6. When it is lower, the current flows from the AC power supply 1 through the diode 4, the rectifier circuit side terminal of the reactor 10, that is, the terminal P1, the capacitor 6 side terminal of the reactor 10, the parallel circuit of the capacitor 6 and the load 7, the terminal N, and the diode 3. I2 flows.

The values of currents 11 and I2 in this operation mode are also l2 = nXI as described above, and the waveform of power supply current i is as shown in Fig. 1 (
This results in a step-like waveform as shown in the negative half-wave period of b).

As described above, according to this embodiment, the waveform of the power supply current i has a step-like shape over its positive and negative sides, so that the number of odd harmonics contained in the power supply current i is reduced.

Next, FIG. 2 shows a modification of the first embodiment, in which the rectifier circuit includes one positive output terminal P and two negative output terminals N1. N
, and has a configuration. Since this operation is the same as that in FIG. 1, the explanation will be omitted.

Next, FIGS. 3 and 4 show a second embodiment of the present invention,
In this embodiment, the AC power supply 1 is of a single-phase three-wire type. That is, FIG. 3 shows the configuration when the output of the rectifier circuit consisting of diodes 2, 4, 8.9 is set to one negative output terminal N and the first and second positive output terminals P and P2, Further, in FIG. 4, the output of the rectifier circuit is connected to one positive output terminal P and first and second negative output terminals N1. This is the configuration when N is set. Note that since the operation in this embodiment can be considered similar to that in the first embodiment, detailed explanation will be omitted.

Next, FIG. 5 shows a third embodiment of the present invention, and this embodiment is a combination of the configurations of FIGS. 1 and 2 according to the first embodiment, and the AC power supply 1 is a single-phase, two-wire system. It is composed of a voltage doubler rectifier circuit.

In addition, in the figure, 8a and 8b are diodes and 10a.

10b is a DC reactor with an intermediate tap, and 6a and 6b are capacitors.

To explain this operation, when the AC power supply voltage is positive and the voltage value is higher than the DC voltage value of the capacitor 6a, the AC power supply 1 is connected to the diode 8a, the intermediate tap of the reactor log, the capacitor 68 side terminal of the reactor 10a, and the capacitor. The current 1□ shown in FIG. 1(b) flows through the series circuit of the capacitor 6a, the load 7, and the capacitor 6b, and the AC power supply voltage is positive and the voltage value is higher than the DC voltage value of the capacitor 6a. When low, connect diode 2 from AC power supply 1.
, rectifier circuit side terminal of reactor 10a, reactor 10
capacitor 6a side terminal of a, capacitor 6a and load 7
The current I2 shown in FIG. 1(b) flows through the series circuit of the capacitor 6b and the capacitor 6b.

The same applies when the AC power supply voltage is negative, and when the absolute value of the AC type g voltage is higher than the DC voltage value of the capacitor 6b, the voltage from the AC power supply 1 passes through the series circuit of the capacitor 6b and the capacitor 6a and the load 7. Through the path, reactor lO
When the current flows through the path passing through the capacitor 6b side terminal of b, the reactor], the intermediate tap of Ob, and the diode 8b, and the absolute value of the voltage g is lower than the DC voltage value of the capacitor 6b, the current flows from the AC power supply 1. A current 2 flows through a path passing through the capacitor 6b and the series circuit of the capacitor 6a and the load 7, and then through the capacitor 6b side terminal of the reactor lOb, the diode 3 side terminal of the reactor IC1b, and the diode 3.

In this embodiment as well, the current 1. The magnitude of , I is determined by the position of the intermediate tap of the accelerator lO, and since the power supply current i has a step-like waveform in both positive and negative directions, the content of odd-order harmonics is reduced.

FIG. 6 shows a fourth embodiment of the present invention, and this embodiment is a combination of the configurations of FIGS. 3 and 4 according to the second embodiment, in which the AC power supply 1 is a single-phase three-wire This is an example having a voltage doubler rectifier circuit of the formula. Note that the operation of this embodiment is based on the third
Since this is the same as the embodiment, the explanation will be omitted.

In the third and fourth embodiments, the DC voltage applied to the load 7 is twice that of the first and second embodiments, so that they are particularly useful as DC power supplies for loads driven at high voltages.

(Effects of the Invention) As described above, according to the present invention, by changing the connection configuration between the rectifier circuit and the DC reactor with an intermediate tap,
Since the power supply current waveform is step-like, if the position of the intermediate tap of the reactor is appropriately selected, the harmonics included in the power supply current can be reduced to 5% for the 3rd harmonic, 5% for the 5th tA wave, etc.
The seventh harmonic is 15%, making it possible to significantly reduce harmonic components compared to the conventional example. This makes it possible to reduce distortion of the voltage waveform in the power supply line and prevent the occurrence of various harmonic disturbances.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1(a) is a circuit diagram showing a first embodiment of the present invention. (b) is a waveform diagram of the power supply voltage and power supply current to explain its operation, FIG. 2 is a circuit diagram showing a modification of this embodiment, and FIG. 3 is a circuit showing a second embodiment of the present invention. 4 is a circuit diagram showing a modification of this embodiment, FIG. 5 is a circuit diagram showing a third embodiment of the present invention, and FIG. 6 is a circuit diagram showing a fourth embodiment of the present invention. Figure 7 (a), Figure 8 (a), Figure 9 (
a) is a circuit diagram showing a conventional example, and FIGS. 7(b), 8(b), and 9(b) are diagrams of power supply voltage and current to explain the operation of each of the above conventional examples, respectively. FIG. 1... AC power supply 2-5, 8, 8 a, 8 b, 9, 9 a, 9b - diode 6.6 a, 6 b... capacitor 7.
...Load 10.10a, 10b...DC actuator P with intermediate tap, P work, P,, N, N□, N2...DC output terminal Fig. 3

Claims (1)

[Scope of Claims] An AC power source, a rectifier circuit connected to the output side of the AC power source, and a smoothing circuit consisting of a DC reactor and a capacitor connected to the output side of the rectifier circuit, the smoothing circuit being connected to both ends of the capacitor. In the DC power supply device that supplies DC voltage to a load, the rectifier circuit includes first and second DC output terminals connected to one polarity of the DC voltage, and a third DC output terminal connected to the other polarity. , the first DC output terminal is connected to the rectifier circuit side terminal of the DC reactor, and the second
A DC power supply device characterized in that a DC output terminal of the capacitor is connected to an intermediate tap of the DC reactor, and a third DC output terminal is connected to a non-DC reactor side terminal of the capacitor.