JPH041596B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an excitation power source for a poloidal field coil (hereinafter abbreviated as PFC) of a tokamak-type nuclear fusion device.

[Conventional technology]

Conventionally, in this type of thyristor power supply, there is a method described in Mitsubishi Atomic Energy Technical Report No. 34, 1982, p. 17, which protects the thyristor rectifier from overvoltage generated by PFC.

Figure 1 shows this conventional example.
is a three-phase AC line, 2 is a three-phase two-winding rectifier transformer, 3 is a three-phase AC input line for a three-phase bridge-connected thyristor rectifier 4, and 41 to 46 are 6 constituting 4.
The thyristors used in the arms of 5 and 6 are 4
a voltage divider circuit element connected between the DC output terminals of 7;
is an isolation amplifier for insulating the terminal voltage of 6 and transmitting it to the subsequent stage; 8 is the voltage between the DC output terminals of the thyristor rectifier 4 detected by the voltage dividing circuit element 6;
A control circuit that gives an ignition signal to the short-circuit thyristor 10 when the voltage at which the P side becomes positive with respect to the N side exceeds a set value, 9 is a gate pulse transformer, 1
1 indicates that the voltage between the upper and lower sides of the thyristor rectifier 4 is detected by the voltage between the DC output terminals of the thyristor rectifier 4 detected by the voltage dividing circuit element 6, when the voltage where the N side is positive with respect to the P side exceeds the set value. A control circuit 12 is a PFC which simultaneously provides firing signals to the thyristors of the series arm, for example 42 and 45. In FIG. 1, the PFC 12 is connected to plasma and other
Because it is electromagnetically coupled to the PFC, sudden changes in plasma current or other PFC currents can cause damage to both ends of the PFC12.
Therefore, a voltage is generated between the DC output terminals of the thyristor rectifier 4. When the generated voltage exceeds the allowable limit of the thyristor rectifier 4, the arm rectifier 42,
45 or the short-circuit thyristor 10 forms a short circuit, and the generated voltage is short-circuited.

Because of the need for PFC current waveform control, two thyristor rectifiers shown in Figure 1 are sometimes prepared and connected in a cross or cascade connection. FIG. 2a shows the case of a cross connection, where the same reference numerals as in FIG. 1 indicate the same parts, and 31 in the figure is a three-phase AC line different from 3. P to N in the figure to PFC
When the current flows in the direction from N to P, the current is supplied from the thyristor rectifier 4 on the left side, and when the current passes in the direction from N to P, the current is supplied from the thyristor rectifier 4 on the right side. Therefore, the overvoltage generated by the PFC is short-circuited by the action of the short-circuit thyristor control circuit 8 or the bypass pair operation control circuit 11 provided in each of the left and right thyristor rectifiers. Second
FIG. b shows a case of cascade connection, and the same reference numerals as in FIG. 1 indicate the same parts. In this case, the overvoltage generated by the PFC 12 is divided by the upper and lower thyristor rectifiers 4 or the short-circuit thyristor 10 because the upper and lower thyristor rectifiers 4 or short-circuit thyristors 10 in the figure are connected in series, and the overvoltage generated by this divided overvoltage is is detected by the two sets of voltage dividing elements 5 and 6 to operate the control circuit 8 or 11. However, if the partial pressure between the upper and lower thyristor rectifiers 4 or the short-circuit thyristor 10 is inappropriate, the upper and lower Only one of them detects overvoltage and performs a short-circuit action, and as a result, the entire voltage generated by the PFC is applied to the non-operating side, and finally overvoltage is detected and a short-circuit action is performed. Therefore, the short circuit of the overvoltage generated by the PFC is delayed, which is not only unfavorable for the insulation of the PFC, but also
It is necessary to design the thyristor rectifier that operates with a delay and the short-circuit thyristor to have a large voltage withstand capacity, which has the disadvantage of being expensive and large.

[Summary of the invention]

The present invention was made in order to eliminate the drawbacks of the conventional ones as described above, and in addition to adding the voltage detection signal of each of the plurality of cascade-connected thyristor rectifiers to its own overvoltage short circuit control circuit, The present invention provides a power supply for PFC that is connected to other overvoltage short-circuit control circuits so as to immediately short-circuit when an overvoltage of the PFC is detected. That is, the present invention provides a method for cascading a plurality of thyristor rectifiers each including an overvoltage detection circuit, a short-circuit thyristor control circuit, a short-circuit thyristor, and a bypass pair control circuit.
When the PFC overvoltages, the voltage detection signal generated by the overvoltage detection circuit corresponding to any thyristor rectifier is sent to the short circuit thyristor control circuit and bypass pair control circuit of all other thyristor rectifiers in addition to itself. This will ignite the shorted thyristor or the bypass pair of each thyristor rectifier.
PFC overvoltage can be shorted all at once.
The purpose is to obtain power for PFC.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 3, 71 and 72 are isolation amplifiers,
81 and 82 are short-circuit thyristor control circuits, 11
1 and 112 are bypass pair control circuits, the same symbols as in FIG. 2 indicate the same parts, and the upper isolation amplifier 7.
The output signal No. 1 is applied to the upper short-circuit thyristor control circuit 81 and the bypass pair control circuit 111, and is also applied to the lower short-circuit thyristor control circuit 82 and the bypass pair control circuit 112. Further, the output signal of the lower isolation amplifier 72 is transmitted to the lower short-circuit thyristor control circuit 82.
and the control circuit 112 for the bypass pair, and the control circuit 8 for the upper short circuit thyristor.
1. It is also added to the bypass pair control circuit 111.

In FIG. 3, among the voltages between the DC output terminals of the thyristor rectifier 4 detected by the voltage dividing circuit element 6, if the voltage at which the P side is positive with respect to the N side exceeds the set value, the short circuit thyristor control circuit 81 and 82 are actuated and provide a firing signal to the short-circuiting thyristor 10 to short-circuit the output side of the thyristor rectifier 4.
Also, when the voltage between the DC output terminals of the thyristor rectifier 4 detected by the voltage dividing circuit element 6, where the voltage on the N side is positive with respect to the P side exceeds a set value, the bypass pair control circuits 111 and 112 are activated. operates,
An ignition signal is simultaneously applied to the thyristors of the upper and lower DC arms of the thyristor rectifier 4, for example, thyristors 42 and 45, to make them conductive.

By configuring as shown in Fig. 3, even if the voltage division between the upper and lower thyristors 4 and the short-circuit thyristor 10 is inappropriate, overvoltage can be detected by the signal on the side that detected overvoltage. Since the non-conducting side also performs the short-circuiting action, the overvoltage of the PFC is immediately short-circuited, and the above-described drawbacks of the conventional device can be eliminated.

Although the above embodiment describes the case where two thyristor power supplies are connected in cascade, the present invention can also be applied to a case where two or more power supplies are used. Further, the thyristor rectifier can be applied to other GTOs, controllable rectifiers using controllable elements such as transistors.

〔Effect of the invention〕

As described above, according to the present invention, when a plurality of independent thyristor rectifiers are used in a cascade connection, each of which is equipped with an overvoltage detection circuit and a means for the thyristor rectifier or short-circuit thyristor to short-circuit the overvoltage when overvoltage is detected. In addition, by simply applying an overvoltage detection signal crosswise to all units, the PFC It is possible to immediately short-circuit the overvoltage generated by the PFC, and is suitable for PFC insulation. It also eliminates the need to design excessive voltage withstand capacity of multiple controllable rectifiers and short-circuit rectifying elements, and is inexpensive and compact. There are benefits to be gained.

[Brief explanation of drawings]

Figure 1 is a circuit configuration diagram when a single conventional PFC thyristor power supply is used, Figure 2a is a circuit diagram when two units of the one in Figure 1 are used in a cross connection, and Figure 2b is a diagram when a cascade connection is used. Circuit configuration diagram: FIG. 3 is a circuit configuration diagram of a cascade connection according to the present invention. From FIG. 1 to FIG. 3, the same reference numerals in the figures indicate the same or equivalent parts, 1 is a 3-phase AC line, 2 is a 3-phase 2-winding rectifier transformer, 3 is a 3-phase bridge-connected thyristor rectifier 4. 3-phase AC input line, 41, 42, 43, 44, 45, 46 are thyristors, 5, 6 are voltage dividing elements, 7, 71, 72 are isolated amplifiers, 8, 81, 82 are short circuit thyristor control circuits, 9 10 is a gate pulse transformer, 10 is a short circuit thyristor, 11, 111, 112 is a bypass spare control circuit, and 12 is a poloidal field coil.

Claims (1)

[Claims] 1. In a power supply for a poloidal field coil in which a plurality of three-phase bridge-connected thyristor rectifiers are connected in cascade, an overvoltage detection means for detecting overvoltage of the DC output of each of the three-phase bridge-connected thyristor rectifiers, on the output side of this overvoltage detection means. rectifier conduction means for conducting all of the three-phase bridge-connected thyristor rectifiers when at least one of the over-voltage detection means detects an overvoltage of a polarity supporting the output current of the three-phase bridge-connected thyristor rectifier; and when the at least one overvoltage detection means detects an overvoltage of opposite polarity to the output of the three-phase bridge-connected thyristor rectifier, all three
Power supply for poloidal field coils with a short-circuit thyristor that shorts the output side of a phase bridge-connected thyristor rectifier.