JP2015082519A - Magnetic field generating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic field generating device capable of generating a desired AC strong magnetic field even if a power source having high output is not used.SOLUTION: A magnetic field generating device includes a plurality of coils 10a, 10b, 20a, and 20b which are coaxially arranged. Moreover, bipolar power sources 31, 32, 33, and 34 are provided independently for each of the plurality of coils 10a, 10b, 20a, and 20b, and each of bipolar power sources 31, 32, 33, and 34 supplies current to the coils 10a, 10b, 20a, and 20b, respectively. Then, electric power outputted from these bipolar power sources 31, 32, 33, and 34 is controlled by a signal generation part 40.

Description

  The present invention relates to a magnetic field generator.

  In recent years, with the electrification of automobiles, a large current is handled in the vehicle, and a strong magnetic field is being generated. For this reason, there is a concern that malfunctions may occur in in-vehicle devices, and there is a need to evaluate the magnetic field resistance of the devices. Since the large current handled inside the vehicle is mainly alternating current, it is necessary to apply an alternating magnetic field to the in-vehicle device in order to evaluate the magnetic field resistance of the in-vehicle device. The Helmholtz coil is used to generate the magnetic field. It is known to generate a magnetic field by passing a current through In addition, in order to evaluate the magnetic field resistance of the device, it is preferable that the shape of a region where the desired magnetic field strength is uniform can be formed with the magnetic field strength according to the use environment of the device.

  For example, in Patent Document 1, a first Helmholtz coil and a second Helmholtz coil are arranged orthogonally, and power is independently supplied to four coils forming the first and second Helmholtz coils. The provided arrangement is disclosed. Each power source is designed to supply a direct current to form a static magnetic field and a gradient magnetic field.

Japanese Patent Laid-Open No. 1-212411

  It is necessary to generate an alternating strong magnetic field that reproduces the environment of an electric vehicle, etc., but since the coil is an inductive load, the impedance changes according to the frequency even if the current value is constant, so high output However, it is necessary to take measures against the power supply because there is a technical difficulty in increasing the output.

  This invention is made | formed in view of this situation, The objective is to provide the magnetic field generator which can produce | generate a desired alternating strong magnetic field, without using a high output power supply.

  In order to solve such a problem, the present invention includes a plurality of coils that are arranged coaxially, a plurality of power supplies that are provided independently for each coil, and that supply alternating current to the corresponding coils, There is provided a magnetic field generation device comprising a signal generation unit for driving each of the power sources.

  Here, in the present invention, it is preferable that the signal generator is configured by a plurality of signal generators each driven by one or more power supplies.

  In the present invention, the number of signal generators is preferably set so that the amount of current supplied to each coil can be controlled.

  In the present invention, it is desirable that the plurality of signal generators synchronize with each other by delivering a reference signal in series and synchronizing each power output.

  According to the present invention, a power source necessary for obtaining a desired alternating strong magnetic field can be shared by the power source for each coil. As a result, the output per power supply can be reduced, so that the current can be driven to the coil without using a high-output power supply, and a desired alternating strong magnetic field can be generated.

Explanatory drawing which shows typically the structure of the magnetic field generator which concerns on this embodiment Explanatory drawing which shows typically another structure of the magnetic field generator which concerns on this embodiment Explanatory drawing which shows typically another structure of the magnetic field generator which concerns on this embodiment

  FIG. 1 is an explanatory diagram schematically showing the configuration of the magnetic field generator according to the present embodiment. The magnetic field generator according to the present embodiment is an apparatus that forms an alternating magnetic field in a predetermined space region. The magnetic field generator is mainly configured by an inner coil pair 10 and an outer coil 20, a plurality of power supplies 31, 32, 33, 34, a signal generator 40, and a controller 50.

  The inner coil pair 10 includes a first coil 10a and a second coil 10b that are arranged coaxially. The individual coils 10a and 10b are set, for example, to have the same shape and the same number of turns, and are arranged so that the surfaces including the coils face each other.

  The outer coil pair 20 includes a first coil 20a and a second coil 20b that are arranged coaxially. The individual coils 20a and 20b are set to have the same shape and the same number of turns, for example, and are arranged so that the surfaces including the coils face each other.

  Further, in the present embodiment, the first coil 20a and the second coil 20b that form the outer coil pair 20 are disposed outside the first coil 10a and the second coil 10b that form the inner coil pair 10 on the inside. It is positioned. The four coils 10a, 10b, 20a, and 20b that form the coil pairs 10 and 20 are configured to be coaxially arranged in series. In the case of a series configuration coil in which the inner coil pair 10 is sandwiched between the outer coil pair 20, the generated magnetic field can be considered as the sum of the magnetic fields generated by the individual coil pairs 10 and 20.

  The plurality of power supplies 31, 32, 33, and 34 are provided independently for each of the coils 10a, 10b, 20a, and 20b. The individual power supplies 31, 32, 33, and 34 are, for example, bipolar power supplies having a function of allowing a desired alternating current to flow regardless of the state of the load. Hereinafter, the power supply 30 will be described as a bipolar power supply 30. The bipolar power supply 31 supplies an alternating current to the first coil 10a. Similarly, the bipolar power supply 32 supplies an alternating current to the second coil 10b. The bipolar power source 33 supplies an alternating current to the first coil 20a, and similarly, the bipolar power source 34 supplies an alternating current to the second coil 20b. Each bipolar power supply 31, 32, 33, 34 supplies a predetermined current (alternating current synchronized with the output signal) to the corresponding coils 10a, 10b, 20a, 20b according to the output signal from the signal generator 40. To do.

  The signal generator 40 drives the four bipolar power supplies 31, 32, 33, and 34, respectively. The signal generator 40 includes four signal generators 41, 42, 43, 44 prepared in a one-to-one relationship with the four bipolar power supplies 31, 32, 33, 34. Each of the signal generators 41, 42, 43, 44 is a general signal generator, and generates an output signal for realizing a predetermined alternating current based on a command from the control unit 11 to be described later. The generated output signal is output to the corresponding bipolar power supply 31, 32, 33, 34.

  Each signal generator 41, 42, 43, 44 incorporates a clock (not shown), and can generate an output signal at a predetermined period. Further, as shown in FIG. 1, these signal generators 41, 42, 43, and 44 have one signal generator 41 as a master, the other signal generators 42, 43, and 44 as slaves, and the master. Synchronizing each other can be achieved by serially transferring the reference signals such as a slave and from the slave to another slave. Therefore, the individual signal generators 41, 42, 43, and 44 synchronously output the output signals for the bipolar power supplies 31, 32, 33, and 34, and the plurality of bipolar power supplies 31, 32, 33, and 34 are respectively driven synchronously. can do.

  The control unit 50 has a function of controlling the magnetic field generator in an integrated manner. As the control unit 50, a computer including a CPU, a memory such as a ROM and a RAM, an HDD (Hard Disk Drive) as an auxiliary storage device, a communication I / F unit, and the like can be used.

  In the magnetic field generator having such a configuration, as described above, the bipolar power supplies 31, 32, 33, and 34 are provided independently for each of the coils 10a, 10b, 20a, and 20b. Therefore, in order to generate a desired alternating strong magnetic field, the output required for each bipolar power supply 31, 32, 33, 34 is supplied to each coil 10a, 10b, 20a, 20b with a single bipolar power supply. Consider the case of supplying current.

  First, consider a case where four coils forming two pairs of coils are driven by a single bipolar power source to generate an alternating magnetic field. Here, it is assumed that the magnetic flux density of the generated AC magnetic field is 100 μT, the frequency is 100 kHz, and the number of turns of each coil is 4 turns. Each of the four coils is an annular coil having a diameter of 1 m, the interval between the coil pairs is 50 cm, and the coils are arranged at equal intervals. In addition, it is assumed that the wire used in each coil is a copper material having a diameter of 17 mm.

The strength of the magnetic field generated by the four coils is represented by the sum of the magnetic fields generated by each coil. Specifically, in the case of two pairs of coils, the current required to form the magnetic field strength under the above conditions is calculated from the following equation. In order to generate an alternating magnetic field with maximum efficiency, it is necessary to pass alternating current synchronously with each coil. When driven by a single bipolar power supply, four coils are electrically connected in series. , Current will be supplied.

  In this equation, I is the current [A] flowing through the coil, r is the radius of the coil [m], b is half the distance between the coils, B is the magnetic flux density [μT], and n is the number of turns of the coil. It is.

When the frequency of the alternating magnetic field is 100 kHz, the voltage applied to the coil is expressed by Equation 5 via Equation 1 and Equations 2 to 4 shown below.

  Here, k is the Nagaoka coefficient, μ is the magnetic permeability [h / m], S is the cross-sectional area of the wire forming the coil, l is the coil length [m], ρ is the wire resistivity [Ωm], and d is The wire diameter [m], ω is each frequency [Hz].

  Referring to the above formula, in order to satisfy the above requirements (magnetic flux density: 100 μT, frequency: 100 kHz), it is necessary to apply a voltage of 270 [V] to the coil. Therefore, in order to do this with a single bipolar power supply, a power supply capable of outputting 270 [V] or higher is used.

  In this regard, as shown in the present embodiment, when the bipolar power supplies 31, 32, 33, and 34 are provided independently for each of the four coils 10a, 10b, 20a, and 20b, the bipolar power supplies 31, 32, and 33 are provided. , 34 should be ¼ of 270 [V], and it can be understood that any power supply capable of outputting more than 70 [V] is sufficient.

  As described above, in the present embodiment, the magnetic field generator is provided with the bipolar power supplies 31, 32, 33, and 34 independently for each of the plurality of coils 10a, 10b, 20a, and 20b. , 33 and 34 supply current to the coils 10a, 10b, 20a and 20b, respectively. These bipolar power supplies 31, 32, 33, and 34 are driven by the signal generator 40, respectively.

  According to such a configuration, the voltage applied to each of the coils 10a, 10b, 20a, and 20b necessary for obtaining a desired alternating strong magnetic field is shared by the individual bipolar power supplies 31, 32, 33, and 34. Can do. Therefore, the bipolar power supplies 31, 32, 33, and 34 do not need to have a high output as compared with the case where the power is realized by a single bipolar power supply. This makes it possible to generate a desired alternating strong magnetic field without using a high-power bipolar power supply.

  Moreover, according to this embodiment, the magnetic field generator has a configuration in which four coils 10a, 10b, 20a, and 20b are coaxially arranged in series.

  According to such a configuration, the pair of coils 10a and 10b forming the inner coil pair 10 is sandwiched inside by the pair of coils 20a and 20b forming the outer coil pair 20. As a result, the directions of the magnetic fields generated by the coil pairs 10 and 20 are the same, so that a strong magnetic field can be formed by adding the individual magnetic fields. That is, using a plurality of coil pairs 10 and 20 arranged in series contributes to the formation of an alternating strong magnetic field, but in order to realize this, a high-power bipolar power supply is required. In this respect, according to the present embodiment in which the necessary voltage can be shared by the individual bipolar power supplies 31, 32, 33, 34, an alternating strong magnetic field can be effectively formed.

  In the present embodiment, the plurality of signal generators 41, 42, 43, 44 synchronize the output signals to the bipolar power supplies 31, 32, 33, 34 by delivering the reference signals in series and synchronizing each other. And output.

  According to such a configuration, the signal generators 41, 42, 43, and 44 can be synchronized with each other by the reference signal. As a result, the AC current can be supplied in synchronization with each other while the voltage is shared by the plurality of bipolar power supplies 31, 32, 33, and 34. As a result, a desired alternating strong magnetic field can be obtained appropriately.

  In the present embodiment, the signal generator 40 is configured such that the bipolar power supplies 31, 32, 33, 34 and the signal generators 41, 42, 43, 44 are set in a one-to-one relationship. 43 and 44 are configured to individually drive one bipolar power supply 31, 32, 33, and 34. However, when the signal generator 40 is composed of a plurality of signal generators, each signal generator may drive two or more bipolar power supplies, and as a result, all of the plurality of bipolar power supplies generate individual signal generators. It is sufficient if it is driven by a container.

  For example, the example shown in FIG. Specifically, the signal generation unit 40 includes two signal generators 45 and 46 each driven by two bipolar power supplies. Here, one signal generator 45 drives two bipolar power sources 31 and 32, respectively, and the other signal generator 45 drives two bipolar power sources 33 and 34, respectively. In this case, each of the signal generators 45 and 46 can synchronize with each other by exchanging reference signals with each other, and can output the aforementioned output signals in synchronization.

  The number of signal generators constituting the signal generator 40 can be determined according to control of the magnetic field strength (control of the amount of current supplied to the coil). For example, it is set in consideration of the case where it is desired to control the strength and the uniform region by changing the current flowing for each coil. If this is not necessary, the signal generator 40 may itself be realized by a single signal generator 47 as shown in FIG.

  Moreover, in this embodiment, the signal generation part 40 is implement | achieved by the several signal generator, and the synchronization signal is utilized in connection with this. However, if the individual signal generators can operate synchronously, this synchronization signal can be omitted.

  As mentioned above, although the magnetic field generator concerning this embodiment was demonstrated, this invention is not limited to this embodiment, A various change is possible in the range of the invention. For example, the number of coils, the number of turns, and the size can be used in various variations.

DESCRIPTION OF SYMBOLS 10 Inner coil pair 10a Coil 10b Coil 20 Outer coil pair 20a Coil 20b Coil 31-34 Bipolar power supply 40 Signal generation part 41-44 Signal generator 50 Control part

Claims (4)

A plurality of coils arranged on the same axis, and
A plurality of power supplies that are provided independently for each coil and supply alternating current to the corresponding coils;
A signal generator for driving each of the plurality of power supplies;
A magnetic field generator comprising:   The magnetic field generator according to claim 1, wherein the signal generator includes a plurality of signal generators each driven by one or more power supplies.   3. The magnetic field generator according to claim 2, wherein the number of the signal generators is set so that the amount of current supplied to each coil can be controlled.   4. The magnetic field generator according to claim 2, wherein the plurality of signal generators synchronize with each other by delivering a reference signal in series and synchronizing each power output. 5.

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