JPS63268209A - Power device for automatic demagnetization of dc electromagnet - Google Patents

Abstract

PURPOSE:To make it possible to demagnetize a DC electromagnet quickly and automatically in an optimum state, by causing a control circuit to output current according to a pattern of demagnetization current from a function generator, and supplying such current automatically to the DC electromagnet while turning its polarity by means of a polarity change-over switch. CONSTITUTION:In order to perform demagnetization, a control circuit 8 turns a change- over switch 4 to the side of contacts S1 and S2, and a function generator 7 is operated to generate a current pattern required for performing demagnetization as stored. The control circuit 8 determines a polarity of the current pattern thus generated and turns a polarity change-over switch 31 to the sides of contacts P1 and P2 or contacts Q1 and Q2. Simultaneously, the control circuit 8 outputs a control command as required for supplying real current according to said current pattern to a DC electromagnet 2, so that the DC electromagnet 2 is supplied with such current exactly according to the current pattern. When current is zero, a current sensor 9 detects it and outputs a detection signal to the control circuit 8. The mode is thereby switched over to the other one for supplying current of the opposite polarity. The control circuit 8 switches the polarity change-over switch 31 and demagnetization is performed in a similar manner.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention automatically reduces the residual magnetic flux to a desired value after excitation of a DC electromagnet used in a particle accelerator, etc., in preparation for the next excitation. This invention relates to an automatic degaussing power supply device for DC electromagnets.

[Conventional technology]

Fig. 3 is a block connection diagram showing a conventional demagnetizing power supply device for DC electromagnets. It is intended to supply

Next, the operation will be explained. In this conventional example, in order to suppress the residual magnetic flux of the DC electromagnet 2 to a level that does not affect the magnetization characteristics of the next excitation, the operation was performed according to the following procedure. That is, the polarity changeover switch 3 is connected to contact P, ,
P, and the excitation power supply 1 causes the DC electromagnet 2 to flow a current with a value slightly lower than the current value that was flowing immediately before the stop (the magnetic flux at this time is shown at point A in Figure 4). After that, lower it to zero. Next, switch the polarity switch 6 to contact Q,
, Q, and the above, Il:! as above. ll
The current is further reduced to zero by passing a slightly lower current. Thereafter, electricity is applied in the same manner, changing the current value and polarity every cycle, and as shown in Figure 4, the residual magnetic flux is gradually reduced according to the hysteresis characteristic curve of the iron core. Demagnetization is completed by suppressing the influence on the next normal excitation characteristic to a value that can be ignored. Note that the final residual magnetic flux at this time is indicated by point B.

[Problem that the invention seeks to solve]

Conventional DC electromagnet degaussing power supplies are configured as described above, so in order to repeatedly reduce the residual magnetic flux, it is necessary to set the current value each time and manually switch the polarity. Moreover, since the power source used for demagnetization is a regular excitation stabilized power supply, there are problems in that it takes a long time to start up and stop the current, and demagnetization takes time and effort.

This invention has been made to solve the above-mentioned problems, and an object of the present invention is to provide an automatic degaussing power supply device for DC electromagnets that can automatically perform degaussing and greatly shorten the time required for degaussing work. purpose.

[Means for solving problems]

The automatic degaussing power supply device for a DC electromagnet according to the present invention includes a function generator that generates a current pattern of degaussing current, and a control circuit that outputs a control command to cause a separately excited converter to output a current that follows this current pattern. The structure is such that a current that follows the current pattern is supplied from the outside to the DC electromagnet by repeatedly reversing the polarity using a polarity changeover switch.

[Effect]

The function generator in this invention has a size of a DC electromagnet,
Automatically generates a current pattern that provides the optimal gradual demagnetization effect according to magnetic characteristics, etc. A control circuit outputs a current that follows this current pattern from a separately excited converter, and the polarity of the current is switched. The switch automatically reverses the polarity while supplying the DC electromagnet with the DC electromagnet, thereby quickly and automatically demagnetizing the DC electromagnet.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, the 10id automatic degaussing unit, 31, is a polarity switching contact P, , P2. A polarity changeover switch with Ql and Qa, 4 a changeover switch with changeover contacts R1, I (2, Sl, and S2) for switching between normal excitation and demagnetization, 5 a transformer, and 6 a thyristor capable of converter operation and inverter operation. A separately excited converter is connected to the transformer 5. 7 is a function generator that generates a degaussing current pattern stored in advance in response to a degaussing start command, and 8 is a function generator that generates a DC current that follows the above current pattern. A control circuit outputs a control command for causing current to flow through the electromagnet 2, and 9 is a current sensor that detects the electromagnet current.

Note that other circuit parts that are the same as those shown in FIG. 3 are designated by the same reference numerals, and redundant explanation thereof will be omitted.

Next, the operation will be explained. When a degaussing start command as shown in FIG. 2(a) l/j, which is not shown in FIG. The contacts S, , S2 are switched to the S2 side as shown in FIG.
Generates a current pattern as shown in . The control circuit 8 determines the polarity of the current pattern and switches the polarity selector switch 6.
1 to contacts P, , P or contacts Q, , Q2 as shown in FIG. is output to the separately excited converter 6. The separately excited converter 6 receives this control command from the control circuit 8 and performs inverter operation (regenerative operation) to operate the converter.
A current according to the above current pattern is applied to the DC electromagnet 2. This current is constantly monitored by a current sensor 9. In this way, when the current becomes zero, the current sensor 9 detects this and inputs it to the control circuit 8, and this control circuit 8 shifts to the current energization mode with the polarity opposite to the previous one, and switches the polarity changeover switch 61. , the same demagnetizing operation as above is performed again. In this way, when all the predetermined degaussing processes are completed, a switching signal is sent from the control circuit 8 to the changeover switch 4, which is connected to the contact Rt.
, R2 to connect the DC electromagnet 2 to the excitation power source 1, and complete demagnetization. In addition, the detection output by the current sensor 9 is shown in FIG.

In the above embodiment, the changeover switches 4 and 31 are shown as having mechanical contacts, but any switch that can be switched by a circuit may be used, such as a transistor switch,
A GTO switch or the like can be used.

Further, in the above embodiment, a thyristor is used as the separately excited converter 6, but any device that can perform converter operation and inverter operation is not limited to the thyristor shown in the embodiment. or other conversion circuits may be used, and the same effects as in the above embodiments can be achieved.

[Effects of the Invention] As described above, according to the present invention, a control circuit outputs a current that follows the current pattern of the degaussing current from a function generator, and this current is sent to a polarity selector switch. Since it is configured to automatically supply the DC electromagnet while reversing the polarity, it is possible to quickly demagnetize the DC electromagnet automatically and in an optimal state without bothering the operator.

[Brief explanation of drawings]

Fig. 1 is a block connection diagram showing a degaussing power supply device for a DC electromagnet according to an embodiment of the present invention, Fig. 2 is a time chart showing signals of each part of the block connection diagram of Fig. 1, and Fig. 3 is a conventional degaussing power supply. FIG. 4 is a block connection diagram showing the device, and a magnetization characteristic curve diagram showing the demagnetization status of the DC electromagnet. 6 is a separately excited converter, 7 is a function generator, 8 is a control circuit, 6
1 is a polarity selector switch. In addition, in the figures, the same reference numerals indicate the same or equivalent parts. Patent applicant: Mitsubishi Electric Corporation (2 others) No. 10

Claims (1)

[Claims] An automatic degaussing power supply device for a DC electromagnet that reduces residual magnetic flux by alternately applying degaussing currents of different polarities to a DC electromagnet includes a function generator that generates a current pattern of the degaussing current, and a function generator that generates a current pattern that follows the current pattern. A DC electromagnet comprising: a control circuit that outputs a control command to be output from a separately excited converter; and a polarity changeover switch that repeatedly supplies a current that follows the current pattern to the DC electromagnet while reversing its polarity. Automatic degaussing power supply.