JPH02142357A - Rectifier - Google Patents

Abstract

PURPOSE:To attain suppression of higher harmonics efficiently and inexpensively by using a rectifier where the input transformer has multiphase secondary windings and the two rectifying circuit are parallely connected to each other through a DC reactor. CONSTITUTION:A transformer 1 has primary windings of star connection and two secondary windings of star and data connections and delta respectively. Two rectifying circuits 3, 2 are connected to the two windings respectively, and the two rectifying circuits 2, 3 are connected to each other in parallel through a DC reactor DCL. The output of the rectifying circuits 2, 3 is smoothed by a smoothing capacitor Cf and supplied to an inverter 4.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a harmonic suppressing diode rectifier used in a DC intermediate circuit of a voltage source inverter.

[Conventional technology]

Conventional rectifiers of this type are shown in Figures 4, 5, and 6.
The circuit diagrams shown in the figure and the circuit diagrams are known.

Figure 4 is a basic circuit diagram of this type of rectifier, where 11 is a three-phase input transformer, 12 is a three-phase full-wave rectifier circuit composed of diodes, Cf is a smoothing capacitor, and 4 is a power transistor. The inverter 5 and 6 are connected in series with each other to form a negative circuit of the inverter 4, and are a negative capacitor and a negative coil.

FIG. 5 shows the circuit diagram of FIG.
An AC reactor A (, L) is inserted and connected to each phase between the next output side and the input end of the rectifier circuit 12, and the positive terminal of the inverter 4 and the smoothing capacitor Ct is connected to the output of the rectifier circuit 12. A DC reactor DCL is inserted and connected between the side positive electrode terminal and the side positive terminal.

FIG. 6 shows one of the transformers 11 in the circuit diagram of FIG.
A three-phase star-shaped harmonic absorption filter HPF consisting of a capacitor and an accelerator connected in series for each phase on the next input side.
are connected in parallel.

[Problem to be solved by the invention]

The diode rectifier circuit becomes a new harmonic power source for its input AC side or output DC side. Incidentally, FIG. 7 is an input AC waveform diagram corresponding to FIG. 4 or FIG. 5, and FIG. 8 is a harmonic content characteristic diagram thereof.

However, depending on the installation of an AC reactor or harmonic absorption filter on the input AC side of the diode rectifier circuit as shown in each of the above conventional methods, or the installation of a DC reactor on the output DC side, the harmonic range that can be effectively suppressed or absorbed is limited. At the same time, due to uncertain wiring inductance, etc., it is necessary to add a design margin for specifying the harmonic range, and the selection of constants of related elements becomes more diverse, leading to higher prices.

In view of the above, it is an object of the present invention to provide a rectifier that is relatively inexpensive and has an effective harmonic suppression function.

(Means for Solving the Problems) In order to achieve the above object, the rectifier of the present invention is a multi-phase rectifier using diodes as rectifying elements, which inputs three-phase alternating current and outputs it to the secondary side. A transformer having a plurality of three-phase secondary windings having different voltage phases and insulated from each other, and a plurality of full-wave transformers each composed of a diode and each receiving the output voltage of each secondary winding of the transformer. A rectifier circuit, a plurality of DC reactors connected in series to each of the positive or negative output terminals of each rectifier circuit, and a common terminal obtained by collectively connecting the anti-rectifier side terminals of each of the reactors. a smoothing capacitor connected between a common terminal obtained by collectively connecting the non-connection side output terminals of the reactors in each of the rectifier circuits, and connecting the DC output side of each of the rectifier circuits to each of the DC The circuit configuration is such that they are connected in parallel via a reactor, and the terminal voltage of the smoothing capacitor is used to obtain the required DC output voltage.

[Effect]

Generally, as the deviation of the waveform from the reference sine wave waveform increases, its harmonic content increases, and conversely, as the deviation decreases as a result of waveform improvement, the harmonic content decreases.

The present invention makes the secondary winding of the input transformer of the diode rectifier circuit multiphase by forming a plurality of windings whose output voltage phases are different from each other and which are insulated from each other. In addition to improving the input AC waveform of
A rectifier device in which a full-wave rectifier circuit with a diode configuration is connected to each of the next windings, and the output DC side of each rectifier circuit is connected in parallel with each other via a DC reactor for preventing harmonic circulation in each circuit. By implementing the circuit configuration shown in FIG. 1, the required harmonics can be suppressed.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

Fig. 1 is a circuit diagram showing an embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
The input AC waveform diagram corresponding to the figure, and FIG. 3 is an example of its harmonic content characteristic diagram. In FIG. 1, the same reference numerals are given to components having the same functions as in the prior art embodiments shown in FIGS. 4, 5, and 6.

FIG. 1 shows a transformer 11 and a rectifier circuit 12 in the circuit diagram shown in FIG. 4, each having two windings: a primary winding (star-shaped), a secondary winding (star-shaped), and Δ (triangle). Transformer 1 and transformer 2
Two sets of rectifier circuits 2 and 3 having a diode configuration connected to the next side and the six windings, respectively, and a DC reactor DCL commonly connecting the positive terminal sides of both circuits are substituted, and both of the rectifier circuits are replaced. The output side of the smoothing capacitor Cf
are connected in parallel via the DC reactor DCL.

As mentioned above, due to the multi-phase secondary side of the transformer 1, its primary side input AC waveform diagram becomes as shown in Figure 2, and its harmonic content characteristic diagram becomes as shown in Figure 3, both of which correspond to each other. This is an improvement over the cases shown in FIGS. 7 and 8.

〔Effect of the invention〕

According to the present invention, in a rectifying device using a diode as a rectifying element, multi-phase input transformer secondary winding of the rectifying device and direct current reactor of each diode rectifier circuit connected to the secondary winding are provided. Parallelization makes it possible to effectively and inexpensively suppress harmonics.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram showing an embodiment of the present invention, and Fig. 2 is a circuit diagram showing an embodiment of the present invention.
Figure 3 is the input AC waveform diagram, Figure 3 is the harmonic content characteristic diagram of Figure 2, Figures 4, 5 and 6 are circuit diagrams showing examples of the prior art, and Figure 7 is the harmonic content characteristic diagram of Figure 2. FIG. 8 is an input AC waveform diagram corresponding to FIG. 5, and FIG. 8 is a harmonic content characteristic diagram of FIG. 1... Transformer, 2, 3... Rectifier circuit, 4... Inverter, 5... Negative capacitor, 6... Negative coil, 11... Transformer, 12... Rectifier Circuit, Cf...
Smoothing capacitor, ACL... AC reactor, DCL
...DC rittle, HPF...harmonic absorption filter. 4

Claims (1)

[Claims] 1) A multi-phase rectifier that uses diodes as rectifying elements, which receives three-phase alternating current as input and has a plurality of three-phase secondary windings on the secondary side that have different output voltage phases and are insulated from each other. Each two of the transformers is composed of a transformer and a diode.
A plurality of full-wave rectifier circuits each receiving the next winding output voltage as input, a plurality of DC reactors connected in series to either the positive or negative output terminal of each of the rectifier circuits, and each of the reactors It comprises a smoothing capacitor connected between a common terminal obtained by collectively connecting the anti-rectifier side terminals and a common terminal obtained by collectively connecting the non-connected side output terminals of the reactors in each of the rectifier circuits. , a circuit configuration in which the DC output sides of each of the rectifier circuits are connected in parallel via each of the DC reactors, and the terminal voltage of the smoothing capacitor is used to obtain the required DC output voltage. Device.