JP5614813B2 - Power supply for electromagnet - Google Patents

Description

  The present invention relates to an electromagnet power supply device for applying a pulsed large current to an electromagnet used in an accelerator or the like.

Accelerators used in fields such as physical chemistry experiments and medicine are equipped with an electromagnet power supply device for applying a pulsed large current to an electromagnet. As a conventional electromagnet power supply device, for example, a device using a power crowbar circuit described in Non-Patent Document 1 is known.
As shown in FIG. 4A, this type of electromagnet power supply apparatus 100 includes a first capacitor 101 and a second capacitor 102 having a capacitance value larger than that of the first capacitor 101. When the second switch 104 is turned ON / OFF, the discharge current (= electromagnet current I) of the first capacitor 101 and / or the second capacitor is applied to the electromagnet 105.

More specifically, in the electromagnet power supply device 100, the first capacitor 101 is charged in advance with a high voltage of several thousand volts and the second capacitor 102 is charged with a voltage of several hundred volts in advance.
Then, as shown in FIG. 4B, when the first switch 103 is turned on at time t ₀ , the discharge current of the first capacitor 101 is supplied to the electromagnet 105, and the electromagnet current I is at the top (for example, several tens of times). stand up to kA).
Thereafter, when the second switch 104 is turned ON at time t _1, the discharge current of the second capacitor 102 is supplied to the electromagnet 105, the current value of the electromagnet current I is maintained near the top.

FIG. 5 shows another conventional electromagnet power supply apparatus 200 whose concept is very similar to that of the electromagnet power supply apparatus 100.
As shown in the figure, the electromagnet power supply apparatus 200 supplies the electromagnet 203 with the discharge current of the first capacitor 204 that is precharged with a voltage of several thousand volts output from the first charging power supply 203. By supplying the electromagnet 203 with the discharge current of the first capacitor 201 that raises the current I to the top and the second capacitor 211 that is precharged with a voltage of several hundred volts output from the second charging power source 210. And a second current source 202 that maintains the current value at.

  In the electromagnet power supply device 200, the conduction state of the two switching elements 205 and 206 is switched between a period in which the electromagnet current I is raised and a period in which the electromagnet current I is maintained. The conduction states of these switching elements 205 and 206 are switched by the control unit 204 connected via an appropriate drive circuit 207.

Tami, “Pulse Power Technology Using Capacitors”, Journal of the Electrostatic Society, 1994, Vol. 18, No. 4, p. 355-363

  By the way, an electromagnet power supply device used in an accelerator is required to continue supplying a certain electromagnet current to the electromagnet for a certain period. In general, the copper loss (impedance) of an electromagnet gradually decreases due to the skin effect, proximity effect, etc. while current is passed. Therefore, in order to keep the current value at the top constant, the electromagnet power supply device desirably lowers the voltage across the electromagnet (hereinafter referred to as “electromagnet voltage”) in accordance with the gradual decrease in the copper loss.

That is, as shown in FIG. 6 (B), the power supply for the electromagnet, while the enhanced electromagnet voltage in the vicinity of the copper loss is relatively large time t _1, in the vicinity of the time copper loss is decreased t ₂ Ideally, the current value of the electromagnet current I at the top is kept constant by lowering the electromagnet voltage.

  However, as shown in FIG. 7A, the electromagnet voltage in the conventional electromagnet power supply apparatus 200 decreases linearly with an inclination depending on the capacitance value of the second capacitor 211 and the current value of the electromagnet current I. Therefore, the current value at the top has changed by an amount corresponding to the difference between the ideal voltage waveform and the actual voltage waveform (see FIG. 7B).

  This invention is made | formed in view of the said situation, The place made into the subject is providing the power supply device for electromagnets which can suppress the fluctuation | variation in the peak part of the pulse-form electric current supplied to an electromagnet.

  In order to solve the above problems, an electromagnet power supply device according to the present invention is an electromagnet power supply device that applies a pulsed current to an electromagnet, and is a first discharge current of a first capacitor that is pre-charged with a first voltage. Is supplied to the electromagnet to supply the electromagnet with the first current source that raises the pulsed current to the top and the second discharge current of the second capacitor that is precharged with the second voltage after the pulsed current rises. And a second current source for maintaining a pulsed current at the top by supplying a third discharge current of a third capacitor precharged with a third voltage to the electromagnet together with the second discharge current. It is characterized by that.

In this configuration, the period for maintaining the pulsed current at the top is divided into a period for supplying only the second discharge current to the electromagnet and a period for supplying the second discharge current and the third discharge current to the electromagnet.
Further, since the second capacitor and the third capacitor are used in the latter period, the total capacitance value of the capacitor that supplies current to the electromagnet is larger than the former period in which only the second capacitor is used.
Therefore, according to this configuration, the slope of the voltage of the electromagnet can be switched between the former period and the latter period, and the slope of the latter period is smaller than that of the former period. Can be approached. That is, according to this structure, the fluctuation | variation in the peak part of the pulse current supplied to an electromagnet can be suppressed.

  In the electromagnet power supply device, when the third voltage is set lower than the second voltage and the pulsed current is maintained at the top, the second current source is a series composed of the second capacitor, the third capacitor, and the rectifying element. The circuit is preferably connected to the electromagnet in parallel.

  In this configuration, only the second discharge current of the second capacitor is supplied to the electromagnet while the voltage of the electromagnet is higher than the third voltage. And if the voltage of a 2nd capacitor falls by discharge and falls below a 3rd voltage, the 3rd discharge current of a 3rd capacitor will also begin to be supplied to an electromagnet. That is, according to this configuration, the two periods can be automatically switched.

  The electromagnet power supply device includes, for example, a first charging power source that outputs a first voltage, a second charging power source that outputs a second voltage, and a third charging power source that outputs a third voltage.

  The electromagnet power supply device includes a first charging power source that outputs a first voltage, a third charging power source that outputs a third voltage, and a fourth charging power source that outputs a fourth voltage. It may be a sum voltage of the third voltage and the fourth voltage.

  ADVANTAGE OF THE INVENTION According to this invention, the power supply device for electromagnets which can suppress the fluctuation | variation in the peak part of the pulse current supplied to an electromagnet can be provided.

It is a circuit diagram of the power supply device for electromagnets concerning a 1st embodiment of the present invention. It is a wave form diagram of the power supply device for electromagnets concerning a 1st embodiment, (A) is a whole wave form figure of electromagnet voltage, (B) is an enlarged wave form figure of (A), (C) is a whole wave form figure of electromagnet current. (D) is an enlarged waveform diagram of (C). It is a circuit diagram of the power supply device for electromagnets concerning 2nd Embodiment of this invention. (A) is a circuit diagram of a conventional electromagnet power supply device, and (B) is a waveform diagram of an electromagnet current. It is a circuit diagram of the conventional electromagnet power supply device. It is a waveform diagram of an ideal electromagnet power supply device, where (A) is an overall waveform diagram of an electromagnet voltage, (B) is an enlarged waveform diagram of (A), and (C) is a waveform diagram of an electromagnet current. It is a wave form diagram of the conventional power supply apparatus for electromagnets, (A) is an enlarged waveform figure of an electromagnet voltage, (B) is an enlarged waveform figure of an electromagnet current.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of an electromagnet power supply device according to the present invention will be described with reference to the accompanying drawings.

[First Embodiment]
FIG. 1 shows an electromagnet power supply device 1A according to a first embodiment of the present invention.
The electromagnet power supply device 1A is for applying an electromagnet current I which is a pulsed large current to the electromagnet 5, and as shown in the figure, the first current source 2, the second current source 3, and these And a control unit 6 for controlling.

  The first current source 2 includes a first charging power source 20 that outputs a first voltage (for example, several thousand volts), a first capacitor 21 that is charged with the first voltage, and four switching elements 25 that are H-bridge connected. , 26, 27, 28.

  The switching elements 25, 26, 27, and 28 of the first current source 2 constitute a bridge circuit unit, and the connection point between the first switching element 25 and the second switching element 26 is the first output terminal, the third switching element 27, and the second switching element. A connection point of the four switching elements 28 is a second output terminal. The first capacitor 21 is connected in parallel to the bridge circuit unit.

  The first switching element 25 and the fourth switching element 28 of the first current source 2 are power semiconductor elements such as IGBTs (Insulated Gate Bipolar Transistors) and are control terminals of the first switching element 25 and the fourth switching element 28. The gate is connected to the control unit 6 through an appropriate drive circuit 29.

  The second current source 3 includes a second charging power source 30 that outputs a second voltage (for example, hundreds of tens of volts), a second capacitor 31 that is charged with the second voltage, and a third voltage that is lower than the second voltage. (E.g., 100 V), a third charging power source 32, a third capacitor 33 charged with a third voltage, a rectifying element 34 connected in series to the third capacitor 33, and four H-bridge connected switchings Elements 35, 36, 37 and 38 are provided.

  The switching elements 35, 36, 37, and 38 of the second current source 3 constitute a bridge circuit unit, and the connection point between the first switching element 35 and the second switching element 36 is the third output terminal, the third switching element 37, and the second switching element 37. A connection point of the four switching elements 38 is a fourth output terminal. The second capacitor 31 and the series circuit of the third capacitor 33 and the rectifying element 34 are connected in parallel to this bridge circuit unit.

  The first switching element 35 and the fourth switching element 38 of the second current source 3 are power semiconductor elements such as IGBTs, and the gates which are the control terminals of the first switching element 35 and the fourth switching element 38 are suitable drive circuits. 39 is connected to the control unit 6 via

  The first output terminal of the first current source 2 and the fourth output terminal of the second current source 3 are connected to the electromagnet 5. The second output terminal of the first current source 2 and the third output terminal of the second current source 3 are directly connected.

In FIG. 1, the first switching element 25, the fourth switching element 28, the first switching element 35, and the fourth switching element 38 of the second current source 3 are controlled by the control unit 6. Therefore, in order to turn these switching elements on and off, drive circuits 29 and 39 are required, respectively.
On the other hand, the second switching element 26, the third switching element 27, and the second switching element 36 and the third switching element 37 of the second current source 3 are turned ON (conductive) / OFF (non-conductive). Since it is not switched and it is not necessary to control by the control part 6, it can cover only with a diode and a drive circuit is unnecessary. This is why the switching elements 26, 27, 36, and 37 are represented by diodes in FIG.

As shown in FIG. 2, the operation of the electromagnet power supply device 1A is divided into four phases I to IV. In each phase, the first switching element 25 and the fourth switching element 28 of the first current source 2 and the first switching element 35 and the fourth switching element 38 of the second current source 3 are controlled by the control unit 6. The conduction state is switched as shown in the table below. Hereinafter, the operation of the electromagnet power supply device 1A in each phase will be described in order.

(Phase I)
Phase I is a preparation phase in which the first switching element 25 of the first current source 2, the fourth switching element 28 of the first current source 2, the first switching element 35 of the second current source 3, and the second current source 3 The first capacitor 21, the second capacitor 31, and the third capacitor 33 are charged with the fourth switching element 38 turned off.
More specifically, the first capacitor 21 is charged by the first voltage output from the first charging power supply 20 until the voltage at both ends reaches several thousand volts, and the second capacitor 31 is output from the second charging power supply 30. The second voltage is charged until the voltage at both ends reaches several hundreds of volts, and the third capacitor 33 is charged by the third voltage output from the third charging power supply 32 until the voltage at both ends reaches approximately 100V. The

  A rectifying element 34 is connected to the third capacitor 33 in series. For this reason, even if the second capacitor 31 is charged to a few tens of volts, the third capacitor 33 does not exceed the voltage value of the third voltage (about 100 V).

The first switching element 25 and the fourth switching element 28 constituting the bridge circuit unit of the first current source 2 are OFF. As described above, the second switching element 26 and the third switching element 27 of the first current source 2 are also OFF.
That is, in the phase I, the first current source 2 and the electromagnet 5 are electrically disconnected, and the electromagnet current I is not supplied from the first current source 2 to the electromagnet 5. Similarly, since the second current source 3 and the electromagnet 5 are also electrically disconnected, the electromagnet current I is not supplied from the second current source 3 toward the electromagnet 5.

(Phase II)
Phase II is a current rising phase. In this phase, the first current source 2 supplies the first discharge current of the first capacitor 21 to the electromagnet 5, whereby the electromagnet current I is raised to the top.

  More specifically, in this phase, the first switching element 25 of the first current source 2, the first switching element 35 of the second current source 3, and the fourth switching element 28 of the first current source 2 are switched from OFF to ON. Thus, the first switching element 25 of the first current source 2 → the first output terminal of the first current source 2 → the electromagnet 5 → the fourth output terminal of the second current source 3 → the third switching element of the second current source 3 37 (diode) → first switching element 35 of the second current source 3 → third output terminal of the second current source 3 → second output terminal of the first current source 2 → fourth switching element 28 of the first current source 2 The first discharge current of the first capacitor 21 flows through this path, whereby the electromagnet voltage rises to the charge voltage of the first capacitor 21 (= first voltage, several thousand volts), and the electromagnet current I reaches several tens of kA. To rise.

  In this phase, the first switching element 35 of the second current source 3 may be turned off and the fourth switching element 38 of the second current source 3 may be turned on. In this case, the first discharge current of the first capacitor 21 is as follows: → the fourth output terminal of the second current source 3 → the fourth switching element 38 of the second current source 3 → the second switching of the second current source 3 The current flows through the path of the element 36 (diode) → the third output terminal of the second current source 3 →.

(Phase III)
Phase III is a current maintenance phase. In this phase, the second capacitor 31 of the second current source 3 and a series circuit composed of the third capacitor 33 and the rectifying element 34 are connected in parallel to the electromagnet 5, and the second current source 3 is connected to the second capacitor 31 of the second capacitor 31. By supplying the two discharge currents and the third discharge current of the third capacitor 33 to the electromagnet 5, the current value of the electromagnet current I at the top is kept constant.

  More specifically, at the beginning of the transition from Phase II to Phase III, the first switching element 25 of the first current source 2 and the first switching element 35 of the second current source 3 remain in the ON state. When the fourth switching element 28 is switched from ON to OFF and the fourth switching element 38 of the second current source 3 is switched from OFF to ON, the first switching element 35 of the second current source 3 → the second current source 3 The third output terminal → the second output terminal of the first current source 2 → the third switching element 27 (diode) of the first current source 2 → the first switching element 25 of the first current source 2 → the first of the first current source 2 The second discharge current of the second capacitor 31 flows through the path of 1 output terminal → electromagnet 5 → fourth output terminal of the second current source 3 → fourth switching element 38 of the second current source 3. At this time, the voltage across the second capacitor 31 decreases from the second voltage (hundreds of tens of volts) with a relatively steep slope (hereinafter referred to as “first slope”) as the second discharge current is released. . Therefore, as shown in FIG. 2B, the electromagnet voltage also decreases with the same slope.

When the voltage across the second capacitor 31 falls below the third voltage, the rectifying element 34 becomes conductive, and the third discharge current of the third capacitor 33 is also electromagnet through the same path as the second discharge current of the second capacitor 31. 5 begins to be fed. The voltage at both ends of the second capacitor 31 and the voltage at both ends of the third capacitor 33 decrease with a predetermined second slope as the second and third discharge currents are released.
Here, since the total capacitance value of the capacitor contributing to the supply of the electromagnet current I has increased, the second slope (the absolute value of the slope) is smaller than the first slope. That is, as shown in FIG. 2B, the gradient of the electromagnet voltage changes from the first gradient to a relatively small second gradient during Phase III.

  The first inclination can be adjusted by the capacitance value of the second capacitor 31. Specifically, the first inclination can be reduced by increasing the capacitance value of the second capacitor 31, and the first inclination can be increased by reducing the capacitance value.

The second inclination can be adjusted by the capacitance values of the second capacitor 31 and the third capacitor 33. Specifically, the second inclination is decreased by increasing the total capacitance value of the second capacitor 31 and the third capacitor 33, and the second inclination is increased by decreasing the total capacitance value. be able to.
If it is desired to adjust only the second inclination without changing the first inclination, the capacitance value of the third capacitor 33 may be adjusted.

  In addition, the timing at which the inclination is switched can be adjusted by the voltage difference between the second voltage and the third voltage. Specifically, when it is desired to delay the switching timing, the voltage difference may be increased. On the other hand, if it is desired to switch at an early stage, the voltage difference may be reduced.

  In the electromagnet power supply device 1A according to the present embodiment, the capacitance value of the third capacitor 33 is set to be twice that of the second capacitor 31, the second slope is set to about ３ of the first slope, and the first By appropriately adjusting the voltage difference between the two voltages and the third voltage, the electromagnet voltage waveform is approximated to an ideal electromagnet voltage waveform.

  That is, according to the electromagnet power supply device 1A, the electromagnet voltage waveform can be approximated to an ideal electromagnet voltage waveform, and fluctuations at the top of the electromagnet current I can be suppressed (FIGS. 2D and 7B). )reference).

(Phase IV)
Phase IV is a current falling phase. In this phase, the first switching element 25 of the first current source 2, the fourth switching element 28 of the first current source 2, the first switching element 35 of the second current source 3, and the fourth switching element of the second current source 3. By setting 38 as shown in Table 1, the supply of a new electromagnet current I by the first current source 2 and the second current source 3 is stopped, and the counter electromotive voltage (-several thousand volts) generated in the electromagnet 5 The current is regenerated in the first capacitor 21.

  In this phase, instead of turning on the fourth switching element 38 of the second current source 3, the first switching element 35 of the second current source 3 may be turned on. Also in this case, the current due to the back electromotive voltage is regenerated in the first capacitor 21.

[Second Embodiment]
FIG. 3 shows an electromagnet power supply device 1B according to a second embodiment of the present invention. The electromagnet power supply device 1B is different from the electromagnet power supply device 1A according to the first embodiment in that the electromagnet power supply device 1B includes the second current source 4 instead of the second current source 3.

  The second current source 4 outputs a third charging power source 42 that outputs a third voltage (for example, 100 V), a third capacitor 43 that is charged with the third voltage, and a fourth voltage (for example, several tens of volts). A fourth charging power source 40, a second capacitor 41 charged with a second voltage that is the sum of the third voltage and the fourth voltage (for example, hundreds of volts), and a third capacitor 43 connected in series. A rectifying element 44 and four switching elements 45, 46, 47, and 48 connected in an H-bridge are provided. However, as in the first embodiment, the second switching element 46 and the third switching element 47 of the second current source 4 are controlled by the control unit 6 without switching ON (conducting) / OFF (non-conducting). Since it is not necessary, it can be covered with a diode, and a drive circuit is unnecessary.

In the electromagnet power supply device 1B according to the present embodiment, since the second capacitor 41 is charged with the second voltage that is the sum of the third voltage and the fourth voltage, in Phase I, the second capacitor 41 is the third capacitor. It is reliably charged to a voltage higher than 43.
Therefore, according to the electromagnet power supply device 1B, it is possible to reliably prevent the discharge of the second capacitor 41 and the discharge of the third capacitor 43 from being started simultaneously in Phase II.

  As mentioned above, although preferable embodiment of the power supply device for electromagnets which concerns on this invention was described, this invention is not limited to the said structure.

  For example, in each of the above embodiments, the current value at the top of the electromagnet current is maintained constant by the discharge currents of two capacitors (second capacitor and third capacitor) precharged with different voltages, but the electromagnet voltage waveform is ideal. More preferably, the number of capacitors is three or more, and the gradient of the electromagnet voltage is switched twice or more from the viewpoint of approximating by the electromagnet voltage waveform.

1A, 1B Electromagnet power supply device 2 First current source 3 Second current source (first embodiment)
4 Second current source (second embodiment)
5 Electromagnet 6 Control Unit 20 First Charging Power Supply 21 First Capacitor 30 Second Charging Power Supply 31 Second Capacitor 32 Third Charging Power Supply 33 Third Capacitor 34 Rectifier

Claims (4)

An electromagnet power supply device for applying a pulsed current to an electromagnet,
A first current source for raising the pulsed current to the top by supplying a first discharge current of a first capacitor precharged with a first voltage to the electromagnet;
After the rise of the pulse current, the second discharge current of the second capacitor precharged with the second voltage is supplied to the electromagnet, and then the third discharge of the third capacitor precharged with the third voltage. A second current source that maintains the pulsed current at the top by supplying current to the electromagnet along with the second discharge current;
An electromagnet power supply device comprising: The third voltage is set lower than the second voltage;
When maintaining the pulsed current at the top, the second current source has a state in which the second capacitor and a series circuit composed of the third capacitor and a rectifying element are connected in parallel to the electromagnet. The power supply device for an electromagnet according to claim 1. A first charging power supply for outputting the first voltage;
A second charging power source for outputting the second voltage;
A third charging power source for outputting the third voltage;
The power supply device for electromagnets according to claim 1 or 2 characterized by things. A first charging power supply for outputting the first voltage;
A third charging power source for outputting the third voltage;
A fourth charging power source for outputting a fourth voltage;
With
The electromagnet power supply device according to claim 1, wherein the second voltage is a sum voltage of the third voltage and the fourth voltage.

Images