JP4974215B2 - Electromagnet power supply - Google Patents

Description

  The present invention relates to an electromagnet power supply apparatus that converts alternating current from an alternating current power supply into direct current and supplies power to an electromagnet coil, and more particularly to an electromagnet power supply apparatus having improved ground fault current detection means.

For example, an electromagnetic power supply for exciting an accelerator electromagnetic coil used in medical and physics research is required to have very high accuracy in order to generate a high-energy stable proton beam. For this reason, the electromagnet power supply apparatus requires high-precision control with a normalized value (ΔIr / Io) of the current ripple ΔIr of the order of 10 ⁻⁴ to 10 ⁻⁶ or less with respect to the rated DC current Io. The control circuit is required to have high stability and high accuracy.

  Here, when the electromagnet coil as a load is grounded due to internal insulation deterioration or the like, since the high-precision control of the current is performed as described above, the output current value of the electromagnet power supply device is kept constant. There is a problem that an error occurs between the magnetic force assumed to cause a ground fault and the actual magnetic force, resulting in a problem in beam control. Therefore, it is an important function for the electromagnet power supply device to reliably detect such a ground fault and perform a necessary protection operation.

Since the above ground fault current circulates through the grounding resistance normally attached to the electromagnet power supply, in the conventional method, the ground fault is detected by detecting and monitoring the current value flowing through the grounding resistance. I was trying to do it. In addition, in order to further improve the accuracy of ground fault detection, a proposal has been made to detect ground faults by applying a DC voltage by a DC power source between an electromagnetic coil and a coil case and detecting this voltage change (for example, patents). Reference 1).
Japanese Patent Laid-Open No. 7-170652 (page 2-4, FIG. 1)

  According to the conventional grounding current detection method using grounding resistance, since the ripple current generated by the AC / DC converter etc. always flows through the stray capacitance between the equipment and the ground, the grounding current is detected. It was difficult. Moreover, since the accelerator has a large facility scale and an electromagnet and a DC bus along with various peripheral devices, it is difficult to find a ground fault location by visual inspection.

  On the other hand, according to the technique disclosed in Patent Document 1, although the detection accuracy can be improved, the circuit configuration is complicated, and a configuration in which a plurality of electromagnet power supplies and a plurality of electromagnets are arranged in series is used. In some cases, it is difficult to reliably detect the ground fault of the electromagnet because the fault current is distributed to a plurality of loops.

  The present invention has been made to solve the above-described problems, and an object thereof is to provide an electromagnet power supply device capable of detecting a ground fault current with a relatively simple circuit configuration. There is to do.

Features of the means for achieving the above object will be described below.

An electromagnet power supply device according to a first aspect of the present invention includes an AC / DC converter that converts AC supplied from an AC power source into DC and a passive filter that smoothes the DC output of the AC / DC converter, and outputs the load to a load. N electromagnet power supply units for supplying direct current by alternately connecting in series with N electromagnet coils N (N is an integer of 2 or more), N bypass switches for short-circuiting the outputs of the respective electromagnet power supply units, The first current detector provided on the positive side of the DC output of any one of the N electromagnet power supply units, and the one electromagnet among the N electromagnet power supply units. A second current detector provided on the negative side of the DC output of the power supply unit, and the N electromagnet power supply units so that the current detected by the first or second current detector becomes a predetermined value. Each Comprising a current control means for controlling the output of the AC-DC converter,
The AC / DC converter of the one electromagnetic power supply unit is operated, the other (N-1) AC / DC converters are stopped, the bypass switch of the output of the one electromagnetic power supply unit is opened, and the other When the (N-1) bypass switches are short-circuited, the N electromagnets are determined by the difference between the current detected by the first current detector and the current detected by the second current detector. It is characterized in that a ground fault of any one of the electromagnetic coils among the coils is detected.

The electromagnet power supply device according to the second aspect of the present invention comprises an AC / DC converter for converting AC supplied from an AC power source into DC and a passive filter for smoothing the DC output of the AC / DC converter, and its output. N-electromagnet power supply units for supplying direct current by alternately connecting in series with N electromagnet coils N (N is an integer of 2 or more), and the positive side of the DC output of each of the N electromagnet power supply units Detected by the first current detector provided, the second current detector provided on the negative side of the DC output of each of the N electromagnet power supply units, and the first or second current detector Current control means for controlling the outputs of the AC / DC converters of each of the N electromagnet power supply units so that the current to be applied becomes a predetermined value, and one of the N electromagnet power supply units The first current detector on the output side The detected current, the current detected by the second current detector on the output side of the adjacent electromagnet power supply unit via the one electromagnet power supply unit and one electromagnet coil to be detected for ground fault The ground fault of the one electromagnet coil is detected by the difference current.

  According to the present invention, it is possible to provide an electromagnet power supply device capable of detecting a ground fault current with a relatively simple circuit configuration.

Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a circuit configuration diagram of an electromagnet power supply apparatus according to Embodiment 1 of the present invention.

  In FIG. 1, an AC voltage supplied from an AC power source 1 is stepped down by a transformer 2 and supplied to an AC / DC converter 3. The direct current obtained by the AC / DC converter 3 is smoothed by the passive filter 4 and supplied to the electromagnetic coil 8 through the ground resistor 5. The AC / DC converter 3 is composed of a plurality of self-extinguishing elements, for example, IGBTs (Insulated Gate Bipolar Transistors), and the electromagnetic coil 8 is controlled by on / off control of the IGBT by a signal from a control circuit 20 to be described later in detail. Supply direct current to Examples of the conversion method of the AC / DC converter 3 include a current type converter and a voltage type converter + chopper. The passive filter 4 is used to reduce current ripple included in the output of the AC / DC converter 3. Usually, it consists of a secondary low-pass filter with a reactor, a capacitor, and a resistor.

  Here, the transformer 2, the AC / DC converter 3, the passive filter 4 and the grounding resistor 5 form an electromagnet power supply unit 10.

  A current detector 6 for detecting a ground fault is connected to the positive side DC output of the electromagnet power supply unit 10, and a current detector 7 for control is connected to the negative side DC output. Given to. Hereinafter, the internal configuration of the control circuit 20 will be described.

The current reference generator 21 generates a DC current reference Id ^* for exciting the electromagnetic coil 8. The subtractor 22 subtracts the direct current value Id detected by the control current detector 7 from the direct current reference Id ^* , and outputs the direct current deviation ΔI (ΔI = Id ^* −Id), which is an output thereof. This is given to the controller 23. The current controller 23 outputs a control amount of a direct current corresponding to the direct current deviation ΔI, and on / off control is performed on the IGBT in the AC / DC converter 3 via the gate controller 24 according to the control amount of the direct current. A signal is given. In this way, the direct current value Id is controlled so that the direct current deviation ΔI becomes zero.

  The output of the current detector 6 is given to the subtracter 25, and the subtracter 25 subtracts the output of the current detector 7 from the output of the current detector 6 and gives the difference to the current detection circuit 26.

In the above configuration, the detected current values of the current detector 6 and the current detector 7 are normally the same value. The electromagnet power supply device controls the output current with high accuracy, and the electromagnet current ripple is less than 10 ⁻⁴ to 10 ⁻⁶ order. Therefore, the current that flows through the stray capacitance between the DC bus and the earth or between the electromagnet coil and the earth Are very few. When a minute ground fault current is generated in the electromagnet coil portion, the difference between the detected current values of the current detector 6 and the current detector 7 increases in proportion to the ground fault current. If the current detected by the current detector 6 is Im and the ground fault current of the electromagnet coil portion is Ig, the current detected by the current detector 7 is Id = Im-Ig.

  Therefore, the difference between the detected current values of the current detector 6 and the current detector 7 becomes Ig, and a small ground fault generated inside the electromagnetic coil is detected by the current detection circuit 26 that detects that this value is equal to or larger than the set value. It becomes possible to do.

  FIG. 2 is a circuit configuration diagram of an electromagnet power supply device according to Embodiment 2 of the present invention. In each part of the second embodiment, the same parts as those in the circuit configuration diagram of the electromagnet power supply apparatus according to the first embodiment shown in FIG. The second embodiment is different from the first embodiment in that n sets of electromagnet power supply units and electromagnet coils are provided as electromagnet power supply units 10a, 10b,..., 10n, and electromagnet coils 8a, 8b,. , A point in which these outputs are connected in series, and bypass switches 9a, 9b,..., 9n that can short-circuit the outputs of the electromagnet power supply units 10a, 10b,. The point is that the current detector 6n for detecting a ground fault and the current detector 7n for control are provided at the outputs on the positive side and the negative side of the electromagnet power supply unit 10n, respectively. Here, n is an integer of 2 or more.

  In the above configuration, only the bypass switch 9n is opened, and the other (n-1) bypass switches 9a, 9b,. Then, only the electromagnet power supply unit 10n is operated, and the other (n-1) electromagnet power supply units 10a, 10b, ... are stopped.

  In this operating state, as in the first embodiment, the detected current values of the current detector 6n and the current detector 7n are normally the same value. When a slight ground fault current is generated in any one of the electromagnet coils 8a, 8b,..., 8n, the difference between the detected current values of the current detector 6n and the current detector 7n becomes the ground fault current. Increase proportionally. If the current detected by the current detector 6n is Im and the ground fault current in the electromagnet coil 8b is Ig, for example, the current detected by the current detector 7n is Id = Im-Ig.

  As described above, in a configuration in which a plurality of electromagnet power supply units and electromagnet coils are provided as a set, and these are connected in series, the electromagnet power supply units other than the set for detecting the ground fault current are stopped, and the bypass switch is short-circuited. By doing so, it is possible to provide an electromagnet power supply device capable of detecting a minute ground fault generated inside any set of electromagnet coils.

  In FIG. 2, the current detector 6n and the current detector 7n are provided only for the output of the electromagnet power supply unit 10n. However, these current detectors are also provided for the outputs of other sets of electromagnet power supply units. May be. Similarly, in FIG. 2, only the output current of the electromagnet power supply unit 10n is controlled and the output of the gate controller 24 is supplied to all the electromagnet power supply units. However, each set is controlled individually. You may comprise so that it may perform.

  Hereinafter, an electromagnet power supply apparatus according to Embodiment 3 of the present invention will be described with reference to FIGS.

  FIG. 3 is a circuit configuration diagram of an electromagnet power supply device according to Embodiment 3 of the present invention. Regarding the respective parts of the third embodiment, the same parts as those of the circuit configuration diagram of the electromagnet power supply apparatus according to the second embodiment of FIG. 2 are denoted by the same reference numerals, and the description thereof is omitted. The third embodiment is different from the second embodiment in that ground fault detection current detectors 6a, 6b,..., 6n and 7a, 7b,. The configuration is such that 10n positive side and negative side outputs are respectively provided, these outputs are given to the current selection comparison circuit 27, and the output of the current selection comparison circuit 27 is given to the current detection circuit 26. .

  In the above configuration, all the bypass switches 9a, 9b,..., 9n are opened, and all the electromagnet power supply units 10a, 10b,.

  Here, the operation of the current selection comparison circuit 27 will be described with reference to FIG. As shown in FIG. 4, in order to detect the ground fault of the electromagnet coil 8a, the current detection value (1) of the current detector 6a for detecting the positive output current of the electromagnet power supply unit 10a for the electromagnet coil 8a and the electromagnet power supply The ground fault current detection is performed by selecting the difference current of the detection value (2 * n) of the current detector 7n that detects the negative side output current of the unit 10n.

  Similarly, in order to detect the ground fault of the electromagnet coil 8b, the current detection value (3) of the current detector 6b that detects the positive output current of the electromagnet power supply unit 10b for the electromagnet coil 8b and the negative value of the electromagnet power supply unit 10a. In order to detect the ground fault current by selecting the difference current of the detection value (2) of the current detector 7a for detecting the side output current and to detect the ground fault of the electromagnetic coil 8n, an electromagnetic power supply unit for the electromagnetic coil 8n The current detection value (2 * n−1) of the current detector 6n that detects the positive output current of 10n and the detection value (2 * n−2) of the current detector 7m that detects the negative output current of the electromagnet power supply unit 10m. ) To detect ground fault current. Here, m = n−1.

  As described above, in a state where n electromagnet power supply units are in operation, the DC current of the positive output of the operating electromagnet power supply unit is adjacent to one another via one electromagnet coil that is a ground fault detection target. If the difference of the direct current of the negative output of the electromagnet power supply unit is detected, the ground fault current of an arbitrary electromagnet coil can be detected.

  According to the present embodiment, it is possible to specify an electromagnetic coil (or a group of electromagnetic coils) in which a ground fault has occurred. Therefore, for example, after detecting the ground fault of any one of the electromagnetic coils by the technique shown in the second embodiment, it is possible to specify an electromagnetic coil in which a ground fault has occurred by the technique of the present embodiment. Further, when the ground fault of the electromagnetic coil is detected only by the method of the present embodiment without using the method shown in the second embodiment, it is not necessary to provide the bypass switches 9a, 9b,.

  In the above description, the current selection / comparison circuit 27 switches the detection current to detect the ground fault current. However, a comparison circuit and a current detection circuit are provided corresponding to each electromagnet power supply unit or electromagnet coil. It is good also as a structure.

  In the description of the first to third embodiments, the components of the electromagnetic power supply unit, that is, the transformer, the AC / DC converter, the passive filter, and the like are not limited to one, and there may be a plurality of units. It may be a combination. The electromagnet power supply unit may be provided with a ripple compensator for suppressing a ripple current.

  Similarly, as for the number of electromagnet coils, it is obvious that one illustrated may be composed of a combination of a plurality of electromagnet coils.

The circuit block diagram of the electromagnet power supply device which concerns on Example 1 of this invention. The circuit block diagram of the electromagnet power supply device which concerns on Example 2 of this invention. The circuit block diagram of the electromagnet power supply device which concerns on Example 3 of this invention. The operation | movement explanatory drawing of a current selection comparison circuit.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 AC power supply 2 Transformer 3 AC / DC converter 4 Passive filter 5 Ground resistance 6, 6a, 6b, 6c, ..., 6n Current detector 7, 7a, 7b, 7c, ..., 7n Current detector 8, 8a Electromagnetic coils 9a, 9b, ..., 9n Bypass switch 10, 10a, 10b, ..., 10n Electromagnet power supply unit

20 control circuit 21 current reference generator 22 subtractor 23 current controller 24 gate controller 25 subtractor 26 current detection circuit 27 current selection comparison circuit

Claims (3)

An AC / DC converter for converting AC supplied from an AC power source to DC and a passive filter for smoothing the DC output of the AC / DC converter, the output of which is an electromagnetic coil N (N is an integer of 2 or more) N electromagnet power supply units that are connected in series with each other to supply direct current,
N bypass switches that short-circuit the output of each of the electromagnet power supply units;
A first current detector provided on the positive side of the DC output of any one of the N electromagnet power supply units;
Of the N electromagnet power supply units, a second current detector provided on the negative side of the DC output of the one electromagnet power supply unit;
Current control means for controlling the output of each AC / DC converter of the N electromagnet power supply units so that the current detected by the first or second current detector becomes a predetermined value;
Operate the AC / DC converter of the one electromagnetic power supply unit, stop the other (N-1) AC / DC converters,
When the output bypass switch of the one electromagnetic power supply unit is opened and the other (N-1) bypass switches are short-circuited,
A ground fault of any one of the N electromagnetic coils is detected based on a difference current between the current detected by the first current detector and the current detected by the second current detector. An electromagnet power supply device characterized by that. An AC / DC converter for converting AC supplied from an AC power source to DC and a passive filter for smoothing the DC output of the AC / DC converter, the output of which is an electromagnetic coil N (N is an integer of 2 or more) N electromagnet power supply units that are connected in series with each other to supply direct current,
A first current detector provided on the positive side of each DC output of each of the N electromagnet power supply units;
A second current detector provided on the negative side of the DC output of each of the N electromagnet power supply units;
Current control means for controlling the output of each AC / DC converter of the N electromagnet power supply units so that the current detected by the first or second current detector becomes a predetermined value;
A current detected by the first current detector on the output side of one of the N electromagnet power supply units;
By the difference current between the one electromagnet power supply unit and the current detected by the second current detector on the output side of the adjacent electromagnet power supply unit via one electromagnet coil that is a ground fault detection target,
An electromagnet power supply apparatus, wherein a ground fault of the one electromagnet coil is detected. N current values detected by a first current detector provided on the positive side of the DC output of each of the N electromagnet power supply units;
Current selection / comparison means for inputting N current values detected by a second current detector provided on the negative side of the DC output of each of the N electromagnet power supply units;
The current selection comparing means is
The current value detected by the first current detector flowing into one of the N electromagnetic coils and the current value detected by the second current detector flowing out of the one electromagnetic coil. The electromagnetic power supply device according to claim 2 , wherein the ground current of each of the electromagnet coils is detected by switching the difference current from the N one after another.

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