JPH09149644A - Single phase diode rectification apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress harmonics generated in an AC input current by using diodes only by a method wherein the DC output of a DC filter circuit and the DC output of a reverse-L type filter circuit are connected in series to each other. SOLUTION: The respective rectified output side capacitors 5 and 8 of the capacitor input type rectifier 10 and the reactor input type rectifier 20 of a rectification apparatus 1 are connected in series to each other and connected to a load 9. An AC input current which is inputted to the single phase primary side of a transformer 2 is converted into a triangular waveform AC current by the capacitor input type rectifier 10 on the secondary side of the transformer 2 and, at the same time, converted into a rectangular waveform AC current by the reactor input type rectifier 20 which is the other rectifier provided on the secondary side. The resultant current of those two AC currents is applied to the primary side of the transformer 2. As the two AC currents are supplied from the same AC power supply, their phases are identical and harmonics can be suppressed by synthesizing the triangular waveform AC current and the rectangular waveform AC current. As a result, an AC input current in which harmonics are suppressed can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a single-phase diode rectifier, and more particularly, to a single-phase diode rectifier for converting single-phase AC power to DC power using a single-phase full-wave diode rectifier circuit. .

[0002]

2. Description of the Related Art Conventional single-phase diode rectifiers used for rectification of AC power are roughly classified into a capacitor input type and a reactor input type depending on the type of a DC filter circuit mounted thereon.

In the capacitor input type single-phase diode rectifier, the AC input current is converted into a triangular pulse current due to the characteristics of the capacitor, and therefore contains many low-order harmonics.

In the reactor input type single-phase diode rectifier, the AC input current is converted into a rectangular wave pulse current due to the characteristics of the reactor. Therefore, when the order of harmonics is N, 1 / N (where N = 1,3,5 ...
・) Contains harmonics.

In these single-phase diode rectifiers, an input current waveform improving method using a self-extinguishing semiconductor device has been proposed in order to suppress harmonics generated in an AC input current by passing through a DC filter circuit. ing.

[0006]

However, in such a conventional single-phase diode rectifier, harmonics generated in an AC input current by using a DC filter circuit of a capacitor input type or a reactor input type. In order to suppress this, an input current waveform improvement method using a self-extinguishing type semiconductor device has been proposed.
In this input current waveform improvement method, control for improving the waveform is performed using the input current or the voltage waveform, so that it is necessary to take measures against external noise and voltage waveform failure, and the circuit becomes complicated. However, there has been a problem that the reliability of the circuit operation is inevitably reduced.

An object of the present invention is to provide a single-phase diode rectifier that suppresses harmonics generated in an AC input current using only a diode without using a self-extinguishing semiconductor device.

[0008]

According to the first aspect of the present invention, there is provided a single-phase diode rectifier comprising: a set of transformers having two sets of secondary windings; A single-phase full-wave diode rectifier circuit is connected, and a reactor is connected to one line of an AC line between a secondary winding of a set of transformers and a single-phase full-wave diode rectifier circuit. A DC filter circuit comprising a capacitor is connected to the DC output stage of the rectifier circuit, and a DC reactor and a capacitor are connected to the DC output stage of the single-phase full-wave diode rectifier circuit connected to the secondary winding of the other set of transformers. And a DC output of the DC filter circuit and a DC output of the inverse L filter circuit are connected in series.

According to the single-phase diode rectifier of the present invention, a single-phase full-wave diode rectifier circuit is connected to each secondary winding of a set of transformers having two sets of secondary windings. A DC filter circuit having a different circuit configuration is connected to each DC output stage of each single-phase full-wave diode rectifier circuit, and the DC output of each DC filter circuit is connected in series to reduce the AC input current. Suppress generated harmonics. That is, one set of single-phase full-wave diode rectifier circuit is a capacitor input type rectifier circuit in which a DC filter circuit composed of a capacitor is connected to its DC output stage,
By inserting a reactor in the AC input stage, the peak value and the current conduction angle of the triangular AC input current generated due to the capacitor characteristics are increased. Another set of single-phase full-wave diode rectifier circuits is a reactor input type reverse LC comprising a DC reactor and a capacitor at the DC output stage.
Type DC filter circuit. Each input stage of the two sets of single-phase full-wave diode rectifier circuits is insulated by a single-phase transformer, and each DC output stage is connected in series.

Therefore, the AC input current input to the primary side of the single-phase transformer is divided into a triangular waveform AC current converted by the capacitor input type filter circuit on the secondary side and the other secondary side. Is combined with the rectangular-wave AC current converted by the reactor input type filter circuit, and a harmonic reduction action is generated.

Therefore, the distortion rate of the DC output current waveform output by the single capacitor input type rectifier circuit and the distortion rate of the DC output current waveform output by the single reactor input type rectifier circuit are different from each other. The distortion rate of the AC input current waveform obtained by combining the output current can be reduced.

Further, the combined AC input current effective value is smaller than the arithmetic sum of the input AC current effective values by the single rectifier circuit, and the AC input power factor can be improved.

[0013]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 and 2 are diagrams showing an embodiment of a single-phase diode rectifier to which the present invention is applied.

First, the structure will be described. FIG. 1 is a diagram illustrating a circuit configuration of a single-phase diode rectifier 1 according to the present embodiment.

In FIG. 1, a single-phase diode rectifier 1 includes a transformer 2, a reactor 3 connected to the u-phase of two sets of secondary outputs of the transformer 2, and a subsequent stage connected to the reactor 3. Single-phase full-wave diode rectifier circuit 4, a capacitor filter including a capacitor 5 connected to the output stage of single-phase full-wave diode rectifier circuit 4, and a capacitor composed of single-phase full-wave diode rectifier circuit 4 and a capacitor filter An input type rectifier 10 and two sets of transformers 2
Of the secondary-side output, an inverted L-type LC filter composed of a single-phase full-wave diode rectifier circuit 6 connected to the a-phase, and a reactor 7 and a capacitor 8 connected to the output stage of the single-phase full-wave diode rectifier circuit 6 And a single-phase full-wave diode rectifier circuit 6
And a reactor input type rectifier 20 composed of an inverted L-type LC filter.

Then, the capacitor input type rectifier 1
The capacitors 5 and 8 of the rectified output of the reactor 0 and the reactor input type rectifier 20 are connected in series and connected to the load 9.

The AC input current input to the single-phase primary side of the transformer 2 is converted into a triangular AC current by the capacitor input type rectifier 10 on one secondary side, and the other secondary side. Are converted into rectangular-wave AC currents by the reactor input type rectifier 20, and a composite current of these triangular AC currents and rectangular AC currents flows to the primary side of the transformer 2.

Since the combined currents are supplied from the same AC power source, the phases thereof match, and a harmonic reduction action is generated by combining the triangular and rectangular AC currents.
The AC input current has harmonics suppressed as compared with a single rectifier.

Next, the operation of this embodiment will be described. FIG. 2 shows the operation of the single-phase diode rectifier 1 of FIG.
It will be described with reference to the timing charts of the signals of the respective parts shown in FIG.

Since the load current Ir is supplied from a DC voltage sufficiently smoothed by the capacitors 5 and 8, the load current Ir is a DC current with little ripple as shown in FIG. U-phase current Iu of the secondary output of transformer 2
Is a current adjusted by the reactor 3 as shown in FIG. That is, u shown in FIG.
The effective value of the phase current Iu is 1 p. u. , The peak value is 2.45
p. u. , The flow angle during the half cycle from (π / 4) to (3
(π / 4) triangular wave current.

The a-phase current Ia of the other set of secondary outputs of the transformer 2 has an effective value of 1 as shown in FIG.
p. u. , The peak value is 1 p. u. Of square wave current. Furthermore, the turns ratio between the primary side of the transformer 2 and the two sets of secondary sides is:
Assuming that 1: 1: 1, the effective value of the AC input current In at this time is a value represented by the following equation (1).

[0022]

(Equation 1)

Further, when this AC input current In is expanded by Fourier series, a value represented by the following equation (2) is obtained.

[0024]

(Equation 2)

Then, the secondary-side u-phase output current I of the transformer 2
u, the secondary side a-phase output current Ia, and the primary side AC input current In
When the current waveforms are compared, the values shown in the following table are obtained.

[0026]

[Table 1]

In this table, the distortion rate of the combined current of the triangular wave AC current and the rectangular wave AC current from the capacitor input type rectifier 10 and the reactor input type rectifier 20 is such that the harmonic current is suppressed as shown in the table. ing.

That is, according to the single-phase diode rectifier 1 of the present embodiment, the distortion rate of the AC input current waveform output by the single capacitor input type rectifier 10 and the single output by the reactor input type rectifier 20 are output. The distortion rate of the AC input current waveform obtained by cascading the DC outputs of the rectifiers is smaller than the distortion rate of the AC input current waveform.

Further, the combined AC input current effective value becomes smaller than the arithmetic sum of the input AC current effective value by the single rectifier, and the AC input power factor is also improved.

In the above embodiment, the reactor 3
Can be substituted by the reactance of the transformer 2 or the reactance of the wiring. The single-phase transformer can omit the secondary winding by setting the DC output voltage.

[0031]

According to the single-phase diode rectifier of the first aspect of the present invention, the distortion rate of the AC input current waveform when the capacitor input type rectifier circuit is single and the AC input current waveform when the reactor input type rectifier circuit is single. Compared with the distortion factor, the distortion factor of the AC input current waveform obtained by combining the AC input currents of the rectifier circuits can be reduced.

Further, the combined AC input current effective value is smaller than the arithmetic sum of the input AC current effective values by the single rectifier circuit, and the AC input power factor can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a circuit configuration of a single-phase diode rectifier to which the present invention is applied.

FIG. 2 is a diagram showing a timing chart of a current signal waveform of each part in the circuit of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Single-phase diode rectifier 2 Transformer 3 Reactor 4 Single-phase full-wave diode rectifier circuit 5 Capacitor 6 Single-phase full-wave diode rectifier circuit 7 Reactor 8 Capacitor 9 Load 10 Capacitor input type rectifier 20 Reactor input type rectifier

Claims (1)

[Claims] 1. A set of transformers having two sets of secondary windings;
A single-phase full-wave diode rectifier circuit is connected to each secondary winding of this transformer, and one of the AC lines between the secondary winding of one set of transformers and the single-phase full-wave diode rectifier circuit is connected. A single-phase full-wave diode connected to a reactor, a DC filter circuit comprising a capacitor is connected to a DC output stage of the single-phase full-wave diode rectifier circuit, and connected to a secondary winding of another set of the transformers. A single-phase diode rectifier, wherein an inverted L-shaped DC filter circuit comprising a DC reactor and a capacitor is connected to a DC output stage of a rectifier circuit, and each DC output of each DC filter circuit is connected in series.