JPH0556643A - Rectifier device - Google Patents

Abstract

PURPOSE:To prevent current unbalance between both commutation groups in a rectifier device using a transformer for the rectifier of double-star connection. CONSTITUTION:Saturable reactors 9a-9f are inserted in series with each diode 3a-3f in order to further fine-adjust inter-tap voltage by the voltage adjustment of a transformer 2 for a rectifier continuously, and control windings 10 for controlling the adsorption voltage of each saturable reactor 9 and bias windings 13 are installed to each saturable reactor 9. The magnitude of bias currents IB1 made to flow through bias windings 13a-13c an bias currents IB2 made to flow through bias windings 13d-13f can be adjusted independently by rheostats 15a and 15b respectively, and current balance between both commutation groups is attained by the adjustment.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rectifier used in, for example, the electrolytic industry.

[0002]

2. Description of the Related Art FIG. 2 shows, for example, Mitsubishi Electric Technical Report Vol.40, No.
It is a circuit diagram which shows the structure of the conventional rectifier of this kind described in 7, 1966 and P1173 to 1181. In the figure, reference numeral 1 is an AC power supply system, and since the output of the device is several tens to several hundreds of MW, it usually receives high voltage of several KV to several tens of KV and extra high voltage. Note that the details of the AC power receiving side devices such as the power receiving side switch are omitted. 2 is a transformer for a rectifier that converts the high voltage of the AC power supply system 1 into the voltage of tens to thousands of volts required for the electrolytic cell.
The AC side winding has a star connection with a tap for gradually changing the transformation ratio, and the DC side winding has a double star connection. 3a to 3f are diodes respectively connected to u-, v-, w-, x-, y-, and z-phase windings on the DC side of the rectifier transformer 2, and 4 and 5 are + (P) -side conductors of the DC output and-( N) side conductors, 6a to 6f are conductors connecting each diode 3 and the DC conductor 4, 7a and 7b are conductors connecting the neutral point of the DC side winding of the rectifier transformer 2 and the DC conductor 5, Reference numeral 8 denotes an interphase reactor, which absorbs the voltage between both commutation groups, that is, the u, v, w phase commutation groups and the x, y, z phase commutation groups, and operates in parallel between both commutation groups. To secure.

Reference numerals 9a to 9f denote saturable reactors inserted between the diodes 3a to 3f and the DC conductor 4 with the conductors 6a to 6f as main windings, and control windings 10a to 10f and bias winding 13a to. It is equipped with 13f. The control winding 10 forms a control current I _c in the winding to flow, AT to main winding forms (ampere-turn) and reverse AT for controlling the absorption voltage of the saturable reactor 9. Also the bias winding
Reference numeral 13 is a winding for flowing a bias current I _B for adjusting the level of the control current to set a predetermined control range, and forms an AT in the same direction as the AT formed by the main winding. 11 and 12 are
A DC power supply for supplying the control current I _C and a controller for controlling the magnitude thereof, and 14 and 15 are a DC power supply for supplying the bias current I _B and a variable resistor for adjusting the magnitude thereof.

It is necessary to adjust the DC output voltage of the rectifier according to the change in the load of the electrolytic cell. However, the tap switching of the rectifier transformer 2 is generally used, and fine adjustment between the tap voltages is possible. This is done by continuously adjusting the control current I _C flowing through the control winding 10 of the saturation reactor 9.

[0005]

By the way, there is a difference in the winding impedance of the rectifier transformer 2 between the two commutation groups u, v, w phases and the x, y, z phases, and the diode 3 is used. If there are characteristic variations in the or saturable reactor 9,
Differences occur in the currents of both commutation groups. In the conventional rectifying device, no means for compensating for these differences is provided, so that it is necessary to select the diode 3 which is large in rating and therefore expensive in consideration of the current imbalance. Due to this current difference, the interphase reactor 8 is subjected to DC excitation, which causes problems such as increased loss and occurrence of overheating. The present invention has been made in order to solve the above problems, and an object thereof is to obtain a rectifying device capable of preventing current imbalance between both commutation groups with a simple structure.

[0006]

The rectifier according to the present invention has a structure in which the bias current supplied to the bias winding can be independently adjusted by both commutation groups.

[0007]

When there is a large or small difference in the currents of both commutation groups, the bias current of both commutation groups is adjusted by adjusting the bias current in the direction of increasing the absorption voltage of the saturable reactor provided in the group where the current increases. Make sure the currents are equal.

[0008]

1 is a circuit diagram showing the structure of a rectifying device according to an embodiment of the present invention. The circuit of the bias winding 13 is different from the conventional circuit shown in FIG. That is, the variable resistor 15 is composed of two variable resistors 15a and 15b.
a is a saturable reactor 9a-9c inserted in the u, v, and w phases
Bias current I _B1 supplied to the bias windings 13a to 13c of
Adjust the size of. Also, the variable resistor 15b is x, y, z
Bias winding of saturable reactor 9d-9f inserted in phase
The magnitude of the bias current I _B2 supplied to 13d to 13f is adjusted.

Initially, with the bias currents I _B1 and I _B2 set to the same value, a DC current of, for example, about 50% of the rated current is made to flow, and the current imbalance between both commutation groups is measured.
Here, for example, if the current on the u, v, w phase side is larger than the current on the x, y, z phase side, the bias current I _B1 is decreased (or the bias current I _B2 is increased). , U, v, w Increase the absorption voltage of saturable reactors 9a to 9c on the phase side (or decrease the absorption voltage of saturable reactors 9c to 9f on the x, y, z phase sides) Direct current of both commutation groups Match the currents. Further, after increasing the direct current to the maximum output level, the bias currents I _B1 and I _B2 are readjusted in the same manner as described above, and the variable resistors 15a and 15b hold the set state at this time. To do so.

As described above, since the currents of both commutation groups can be balanced at the maximum output level which is the most severe as a load condition, it is not necessary to consider the current imbalance between the groups when selecting the diode 3. Therefore, it is possible to use inexpensive elements and reduce the cost of the device. Further, since the interphase reactor 8 is also not subjected to DC excitation, the loss is reduced and the temperature rise is also reduced.

[0011]

As described above, according to the present invention, since the bias currents can be independently adjusted in both commutation groups, the imbalance of the DC currents in both groups can be reliably eliminated.

[Brief description of drawings]

FIG. 1 is a circuit diagram showing a configuration of a rectifying device according to an embodiment of the present invention.

FIG. 2 is a circuit diagram showing a configuration of a conventional rectifier.

[Explanation of symbols]

2 rectifier transformer 3a~3f diode 8 interphase reactor 9a~9f saturable reactor 10a~10f control winding 13a~13f bias winding 15a, 15b variable resistor I _C control current I _B1, I _B2 bias current

Claims (1)

[Claims] 1. A rectifier transformer having a double star connection, a diode connected to each DC side winding of the rectifier transformer,
A main winding is connected in series with each of the above-mentioned diodes and a control winding for flowing a control current for controlling the absorption voltage and a bias for supplying a bias current for adjusting the level of the control current to set a predetermined control range. A saturable reactor having a winding and a rectifying device having an interphase reactor for absorbing a voltage between the two commutation groups on the DC side to ensure parallel operation between the two commutation groups. A rectifying device characterized in that the bias current supplied to the line can be independently adjusted by both of the commutation groups.