JP2922269B2 - Thyristor converter - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thyristor converter in which thyristors are connected in anti-parallel to improve characteristics during regenerative operation.

[Conventional technology]

FIG. 6 is a circuit diagram showing, for example, a conventional thyristor converter, in which 1 is an AC power supply, 2 is a forward converter CONV1 that outputs a forward current, and a reverse converter that outputs a reverse current. A thyristor converter composed of CONV2, 3 is a DC load connected to the DC output side of the thyristor converter 2, for example, a DC machine (DCM), 4 is a mechanical load, 5 is a power supply having reactance and resistance components. Impedance.

Next, the operation will be described. First, FIG. 7 shows an operation waveform diagram of the thyristor converter of FIG. 6. In FIG. 7, e _uw in FIG. 7A shows a line voltage waveform between the U phase and the W phase of the AC power supply 1, and e _{uo. Shows} the U-phase voltage waveform of the AC power supply 1, and e _uo is ahead of e _uw by 30 °.

Now, when the thyristor converter 2 is operating in the power running (converter) mode at the control angle α = 0 °, as shown in FIG. 6, the current flows through the following path during the firing period of the thyristor elements TH1 and TH2. . That is, the U phase of the AC power supply 1 → the power impedance Z of the U phase → the thyristor element TH1 → the DC load 3
→ Thyristor element TH2 → W phase power impedance Z →
W-phase of the AC power supply 1, and the DC load 3 is applied a DC voltage E _d of the solid arrow direction shown in FIG. 6 is, the DC current I _d is energized. The U-phase current (I _U ) of the AC power supply 1 at this time is the seventh
A rectangular wave current indicated by oblique lines in FIG. 2B is obtained (however, it is assumed that the inductance of the DC load 3 is sufficiently large). The fundamental wave current I _U1 of the U-phase current I _U of this rectangular wave is shown by a broken line in FIG.
e Becomes in phase with _U0 .

Then the thyristor converter 2 is, if you are regenerated (inverter) operating at the control angle alpha = 180 ° is the DC load 3 voltage E _d of the dotted arrow direction as shown in FIG. 6 is generated cage, the direct current I _d of the power running operation at the same direction are energized.
The U-phase current AC power source 1 at this time becomes a rectangular wave current shown by oblique lines in Figure No. 7 (c), the fundamental current I _U1 is as shown by a broken line in (c) FIG, from the phase voltage e _U0 180 ° delay.

FIG. 8 is a vector diagram showing the relationship between the phase voltage e _U0 of the AC power supply 1, the phase current I _U1 , and the phase voltage e _U at the input terminal of the thyristor converter.

In FIG. 8 (a), e _U0 (vector ▼) indicates the power supply phase voltage, whereas the phase current I _U depends on the operation mode of the thyristor converter 2 as described in FIGS. 6 and 7. , The same phase as the phase voltage (α = 0 °) to the opposite phase (α = 180 °)
To change. I _{U1 in} FIG. 8 (a) shows this change, and the vector ▼ represents the vector ▲ when α = 0 °.
▼ indicates α = 90 °, and vector ▲ ▼ indicates α = 180 °. FIG. 8 (b) shows the power supply phase voltage e _U0 (vector ▲
▼) shows the relationship between the thyristor converter input terminal phase voltage e _U , and from _U = _U 0 _{−U 1} , as the phase current I _U1 changes with the control angle α as shown by the broken line, the input voltage e _U becomes a vector ▲ ▼ (Α = 0 °), vector G (α = 90
°) and the vector ▲ ▼ (α = 180 °). Accordingly, the trajectory of the vector end of the input terminal voltage e _U is indicated by the broken line in (b).

Thus, (b) the thyristor input voltage as is clear from FIG. E _U minimum vector ▲ ▼, varies greatly with vector ▲ ▼ at the maximum.

[Problems to be solved by the invention]

Since the conventional thyristor converter is configured as described above, the phase current phase changes between the power running operation and the regenerative operation by a maximum of nearly 180 °, so that the voltage fluctuation at the input terminal of the thyristor converter is very large. Becomes This voltage fluctuation has a larger fluctuation when the power supply system is weak, in other words, when the power supply impedance is large, and may cause abnormal operation of the thyristor converter itself or other devices connected to the same power supply system. there were.

As an approximation technique, for example, there is a technique described in Japanese Utility Model Publication No. 47-4655, "Static Leonard Device".

The present invention has been made in order to solve the above-described problems, and reduces voltage fluctuation at an input terminal of a thyristor converter that operates in a regenerative operation or a power running operation even when an AC power supply is weak, so that the same AC power supply is used. It is an object of the present invention to obtain a thyristor conversion device capable of stably operating the thyristor conversion device itself without adversely affecting other devices connected to the thyristor.

[Means for solving the problem]

A thyristor conversion device according to the present invention includes a forward converter and a reverse converter, an AC power supply is connected to the AC side, and a DC load for performing powering operation and regenerative operation is connected to the DC side. A thyristor converter, a resistor connected between each phase of an AC input terminal of the thyristor converter, and a switch for turning on the resistor only during regenerative operation.

[Action]

The thyristor converter according to the present invention connects the resistor to the AC power supply only during the regenerative operation. As a result, the currents flowing through the thyristor converters (with a phase delay of 90 ° to 180 ° with respect to the AC power supply) cancel each other.

Therefore, the voltage drop due to the power supply impedance is reduced, and the voltage fluctuation of the thyristor converter is also reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, the same parts as in FIG. 6 are denoted by the same reference numerals. In FIG. 1, reference numeral 6 denotes a resistor R connected between the respective phases of the AC power supply input terminal of the thyristor converter, and 7 denotes a resistor R6. The switch 7 is connected, and the switch 7 is turned on only when the thyristor converter 2 performs a regenerative operation.

Next, the operation will be described. First, FIG. 2 shows an operation waveform diagram of the thyristor converter of FIG.
(A) is a U-phase voltage waveform of the AC power supply 1.

FIG. 2B shows that the thyristor converter 2 is connected to the U-phase current fundamental wave I _U1 (dashed line in the figure) and the U-phase when the thyristor converter 2 is performing regenerative operation at the control angle α = 180 °. The resistance load current I _RU (solid line in the figure) flowing through the resistor 6 is shown. Resistance load current I
_RU has the same phase as the phase voltage e _U0 as shown in FIG. The current I _U0 flowing through the power supply impedance 5 is _U0 = _U1 +
_If the resistance R of the resistor 6 is selected so that the absolute values of I _U1 and I _RU are equal (see FIG. 3),
The current I _U0 becomes zero. Therefore, the voltage drop _{IU0.Z at the} power source impedance Z also becomes zero.

Therefore, the input terminal voltage e _U of the thyristor converter 2 is expressed by _U
= _U0 - _U0 = _U0 , which is equal to the power supply phase voltage _eU0 .

FIG. 3 is a diagram showing the above relationship in a vector diagram.

FIG. 4 shows the relationship between the converter regenerative current I _U1 , the resistance load current I _RU, and the phase power supply I _U0 (= I _U + I _RU ) when the control angle changes from α = 90 ° to α = 180 °. FIG.
As described above, when I = 180 °, I _U0 = 0, and when α = 90 °, I _U0 takes the value indicated by the vector ▼.

When control angle α changes between 90 ° and 180 °, phase current _IU0 changes along a locus indicated by a broken line in the figure.

FIG. 5 (a) shows that the phase voltage e _U at the input terminal of the thyristor converter 2 is changed during the regenerative operation (α = 90 °) based on the above results.
〜180 °) in a vector diagram.

FIG. 5 (b) is a vector diagram of e _U during the converter operation when α = 0 ° to 90 °.

As apparent from the comparison between FIG. 8 in Figure 5 and prior art device, the voltage fluctuation range e _Q in the thyristor converter input is reduced to about 1/2.

〔The invention's effect〕

As described above, according to the present invention, since the resistor is connected between the phases of the AC power supply only when the thyristor converter performs the regenerative operation, the currents flowing through the thyristor converter are canceled each other, and the AC power supply input terminal Is also greatly reduced. Thus, there is no adverse effect on other devices connected to the same AC power supply, and stable operation is possible. In particular, when the power supply system is weak and the power supply impedance is large, the effect is more excellent.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a thyristor conversion device according to an embodiment of the present invention, FIG. 2 is an operation waveform diagram of a main part thereof, and FIGS. 3, 4, and 5 are diagrams for explaining the operation of FIG. Vector illustration of a
FIG. 6 is a circuit diagram of a conventional thyristor conversion device, FIG. 7 is an operation waveform diagram of a main part thereof, and FIG. 8 is a vector diagram for explaining the operation of FIG. In the figure, 1 is an AC power supply, 2 is a thyristor converter, 3
Is a DC load, 6 is a resistor, and 7 is a switch. In the drawings, the same reference numerals indicate the same or corresponding parts.

Claims (1)

(57) [Claims] 1. A thyristor converter comprising a forward converter and a reverse converter, wherein an AC power supply is connected to the AC side, and a DC load for powering operation and regenerative operation is connected to the DC side. A thyristor conversion device, comprising: a resistor, a resistor connected between each phase of an AC power input terminal of the thyristor converter, and a switch for turning on the resistor only during regenerative operation.