JPS6111070B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a plurality of transformers each connected to two or more sets of secondary windings wound around one transformer and supplying rectified power to loads to be operated simultaneously. The present invention relates to a control method for a thyristor converter.

Thyristor-type AC vehicles often use thyristor converters in the form described above, and in such cases, harmonic currents flowing through overhead wires can cause inductive disturbances to nearby communication lines. often occurs. Conventionally, filters have been added to suppress these harmonics, but this method is only effective against specific harmonics, and requires extra space to install the filter, resulting in an increase in weight. It had the disadvantage of being accompanied by

It is an object of the invention to provide a method for controlling a thyristor converter without the problems of increased space and weight.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will now be described in detail with reference to preferred embodiments thereof, with reference to the drawings.

FIG. 1 is a simplified circuit diagram of a thyristor converter to which the present invention is implemented, and FIG. 2 is an explanatory diagram of operating waveforms illustrating the control method according to the present invention in proportion to the conventional method.

In Figure 1, a transformer 1 has a first set of secondary windings 2-1 to 2-4 and a second set of secondary windings 2-5 to 2-8; Thyristor converters 3-1 and 3-2 are connected to the next windings, respectively. The primary side of the transformer 1 is connected to an overhead wire (not shown). The thyristor converter 3-1 consists of a plurality of thyristor rectifiers (without reference numbers) connected as shown, the rectified output of which is connected to the load DC motor 5-1 via a reactor 4-1. On the other hand, the thyristor converter 3-2 also consists of a plurality of thyristors,
The rectified output is supplied to a DC motor 5-2, which is a load, via a reactor 4-2. For each thyristor converter 3-1, 3-2, the secondary winding of the transformer 1 is multi-divided, a thyristor rectifier is connected to each of the secondary windings, and these are connected in cascade. As a result, induced disturbances to communication lines due to harmonic currents are reduced to some extent. FIG. 2A shows the transformer primary voltage waveform together with a command firing angle α supplied from a firing angle command device (not shown).

In the conventional method, the thyristor rectifier group belonging to the thyristor converter 3-1 and the thyristor converter 3-2
The thyristor rectifiers belonging to the transformer 1 are all controlled at the same firing angle α, and the primary current waveform of the transformer 1 at that time is shown in FIG. When the transformer primary current waveform is not smooth and changes as shown in FIG.

On the other hand, in the present invention, as shown in FIG.
-Δα, the change in the primary current of the transformer 1 during the commutation period of both thyristor rectifier groups is made smoother than in the conventional control method, and the harmonics contained are reduced.

Although FIG. 1 shows the case where two sets of thyristor converters are provided on the secondary side of the transformer 1, the number of thyristor converters may be three or more, in which case K is an integer. 0, 1, 2, ..., the firing angle of each thyristor converter is an integer multiple KΔα of a preselected small phase angle Δα with respect to the command firing angle α supplied from the firing command device. Leading or lagging phase angles α±KΔα and phase differences are provided such that the firing angles of all thyristor transducers are arranged symmetrically around α in front and behind it.

In addition, as mentioned above, the firing angle of the thyristor converter is changed from the command firing angle α to KΔα (K=1 in Figure 2 C).
If the thyristor converter is shifted forward or backward by only the thyristor converter used, a difference will occur in the average value of the DC output voltage of each thyristor converter.
Since this difference is small, it does not cause any particular problem in normal use. However, it is desirable, and in some cases necessary, to keep the average DC output voltage of each thyristor converter the same if possible. Third
4 and 5 are diagrams illustrating a method for achieving this in the present invention, taking as an example the case where the number of thyristor converters is three.

In FIG. 3, thyristor converters 3-1, 3-2 and 3-3 connected to three sets of secondary windings of transformer 1 are connected through reactors 4-1, 4-2 and 4-3, respectively. rectified power is supplied to DC motors 5-1, 5-2, and 5-3. In addition,
In FIG. 3, in order to simplify the drawing, the secondary windings and the thyristor converters are shown grouped together without even being shown in detail individually.

Figure 5 A, B, and C illustrate the firing angles of the thyristor rectifiers 3-1, 3-2, and 3-3, respectively, and the firing angle at which the firing angle of each thyristor converter corresponds to the command firing angle. The three thyristor converters are switched to an advanced phase α ₁ and a delayed phase α ₃ at a predetermined period T with respect to α ₂ , and moreover, within an arbitrary period t within the period T, in other words, at an arbitrary time, the three thyristor converters It is shown that the same relationship as shown in FIG. 2C is maintained between them. Figure 4 B, C and D show the individual primary current waveforms when the thyristor converter is fired at firing angles α ₃ , α ² and α ₁ , and Figure 4 A shows the composite primary current waveform, i.e. This shows the current waveform that actually appears on the primary side of the transformer. As is clear, thyristor converters 3-1, 3-2, 3-3
The average values of the DC output voltages are all equal to the values for firing at firing angle α ² and remain the same.

In addition to being used for railway vehicles, the present invention has two or more sets of secondary windings in one transformer, a thyristor converter is connected to each winding, and a transformer rectifier that is controlled in the same way is used as a power source. It is also applicable to group operation of devices such as DC machines and electric furnaces.

As can be understood from the above explanation, the present invention can be implemented simply by adding an inexpensive and small-sized phase shifter for shifting the ignition pulse phase, and the problem of increased space and weight can be avoided. Moreover, it provides an excellent harmonic suppression effect.

[Brief explanation of the drawing]

Fig. 1 is a simplified circuit diagram of a thyristor converter to which the present invention is applied, Fig. 2 is an explanatory diagram of operating waveforms for explaining the control method according to the present invention in comparison with a conventional method, and Fig. 3 is a diagram illustrating the control method according to the present invention in comparison with a conventional method. A diagram illustrating another thyristor converter for implementation, FIG. 4 is an explanatory diagram of operating waveforms for FIG. 3, and FIG. 5 shows switching of the firing angle of each thyristor converter shown in FIG. 3. It is a diagram. 1: Transformer, 3-1, 3-2, 3-3: Thyristor converter, 4-1, 4-2, 4-3: Reactor, 5-1, 5-2, 5-3: DC motor.

Claims (1)

[Claims] 1. In order to supply rectified power connected to two or more sets of secondary windings wound on one transformer to loads to be operated at the same time, according to a common command firing angle. A control method for a plurality of thyristor converters to be controlled, characterized in that the firing angle of each thyristor is commanded to vary by a preselected small value in the vicinity of the command firing angle. Control method for thyristor converter.