JP2008270274A - Magnetizer - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To properly magnetize a small magnet of high coersive force such as a rare earth-iron magnet while restraining heat generation from a magnetizer. <P>SOLUTION: In the magnetizer having a charging capacitor 10 to be charged with high voltage through a step-up transformer 3, a magnetization coil 7 to be supplied with charges from the charging capacitor 10 through a switch 6, and a flywheel diode 8 connected in parallel with the magnetization coil 7, the charging capacitor 10 is constituted of a plurality of capacitors 10a and 10b connected in parallel, one end of each of the plurality of capacitors 10a and 10b is connected to the input side of the switch 6 through parallel wirings 11a and 11b, and the other end of each of the plurality of capacitors 10a and 10b is connected to the connection point of the magnetization coil 7 and the flywheel diode 8 through the parallel wirings 11c and 11d. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetizing apparatus suitable for use in magnetizing a high-retention rare-earth iron magnet or the like used in, for example, a small stepping motor.

  Conventionally, a magnetizing apparatus as shown in FIG. 6 has been proposed. In FIG. 6, reference numeral 1 denotes a commercial power supply of 100 VAC or 200 VAC, and one end of the commercial power supply 1 constitutes a thyristor that constitutes a phase control circuit that controls the phase of the commercial power supply according to the charging state of a charging capacitor 5 described later. The (SCR) 2a is connected to the anode and the thyristor 2b is connected to the cathode, respectively.

  The cathode of the thyristor 2a and the anode of the thyristor 2b are connected to the other end of the commercial power supply 1 via the primary winding 3a of the step-up transformer 3, respectively. In this case, a control signal corresponding to the charging state of the charging capacitor 5 is supplied to the respective gates G of the thyristors 2a and 2b, and this control signal causes a phase to be applied to the primary winding 3a of the step-up transformer 3. The desired AC voltage is controlled.

  One end of the secondary winding 3b of the step-up transformer 3 is connected to one input terminal of the double-wave rectifier circuit 4 formed of a diode bridge, and the other end of the secondary-side winding 3b is the other end of the double-wave rectifier circuit 4. Connected to the input terminal. A charging capacitor 5 of 400 μF, for example, is connected between the positive output terminal and the negative output terminal of the both-wave rectifier circuit 4. In the conventional example shown in FIG. 6, the voltage across the charging capacitor 5 is charged to 1250 V, for example.

  The connection point between the positive output terminal of the both-wave rectifier circuit 4 and the charging capacitor 5 is connected to the anode of a thyristor (SCR) 6 constituting the switch, and the cathode of the thyristor 6 is connected to one end of the magnetizing coil 7. Yes. The other end of the magnetizing coil 7 is connected to the negative output terminal of the both-wave rectifier circuit 4. In the conventional example shown in FIG. 6, a flywheel diode 8 is connected in parallel to the magnetizing coil 7.

  In the conventional example shown in FIG. 6, when magnetizing the magnetized object, the magnetized object is arranged in a predetermined relationship with respect to the magnetizing coil 7, and the charging capacitor 5 is charged to 1250V, for example. Thereafter, a control signal is supplied to the gate G of the thyristor 6 to turn on the thyristor 6.

  At this time, a pulse current flows through the charging capacitor 5 → the thyristor 6 → the magnetizing coil 7 → the charging capacitor 5, and a pulse magnetic field is generated in the magnetizing coil 7 by this pulse current, so that the object to be magnetized is magnetized. can do.

  In this case, a flywheel diode 8 is connected in parallel to the magnetizing coil 7, and this flywheel diode 8 becomes conductive when the voltage of the charging capacitor 5 becomes approximately 0 V, and the magnetizing coil 7 and the flywheel diode 8 are connected. Circulating current flows through This circulating current is naturally attenuated to zero by the resistance component R2 of the magnetizing coil 7 and the wiring resistance.

  In the conventional example shown in FIG. 6, the capacitance of the charging capacitor 5 is C, the resistance component including the wiring from the charging capacitor 5 to the magnetizing coil 7 and the thyristor 6 is R1, the inductance of this wiring is L1, The resistance component of the magnetizing coil 7 is R2, the inductance of the magnetizing coil 7 is L2, and the voltage across the charging capacitor 5 is V0.

…（１）
但し、Ｌ＝Ｌ１＋Ｌ２、Ｒ＝Ｒ１＋Ｒ２、

となり、この最大着磁電流Ｉが流れるまでの時間Ｔは、

…（２）
であらわされる。 The maximum magnetization current I of the conventional example shown in FIG.

... (1)
However, L = L1 + L2, R = R1 + R2,

The time T until the maximum magnetization current I flows is

... (2)
It is expressed.

The technique related to the conventional magnetizing apparatus described above is described in Patent Document 1.
JP-A-6-302433

  By the way, in recent years, stepping motors and the like have been reduced in size and torque, and NdFeB bond magnets and the like that can be injection-molded with a high holding force are used for these stepping motors and the like. NdFeB bond magnets and the like used for such small stepping motors are required to have a minimum diameter of, for example, φ2 mm and multipolar magnetization.

  For this reason, it is necessary to reduce the diameter of the magnetizing coil 7 wound around the magnetizing yoke that magnetizes the magnet, and generate a sufficiently high magnetic field to magnetize the NdFeB-based bonded magnet having a high holding force. There was a need to do. However, the conventional magnetizing apparatus as shown in FIG. 6 has a disadvantage that a sufficiently high magnetic field cannot be generated, and good magnetization cannot be performed.

  Further, there has been a problem that heat generation is increased by reducing the wire diameter of the magnetizing coil 7 wound around the magnetizing yoke.

  In view of such a point, the present invention has an object to satisfactorily magnetize a magnet having a high holding force such as a small NdFeB-based bonded magnet and to suppress heat generation of a magnetizing device.

  A magnetizing device of the present invention includes a charging capacitor that is charged to a high voltage via a step-up transformer, a magnetizing coil that is supplied with electric charge from the charging capacitor via a switch, In a magnetizing apparatus having a flywheel diode connected in parallel to the magnetizing coil, the charging capacitor is composed of a plurality of capacitors connected in parallel, and one end of each of the plurality of capacitors is connected in parallel. The wiring is connected to the input side of the switch, and the other end of each of the capacitors is connected to the connection point of the magnetizing coil and the flywheel diode through a parallel wiring. It is.

  The magnetizing device of the present invention includes a charging capacitor that is charged to a high voltage via a step-up transformer, and a magnetizing coil that is supplied with electric charges from the charging capacitor via a switch. And a flywheel diode connected in parallel to the magnetizing coil, the switch is composed of a plurality of switching elements, and the charging capacitor is composed of a plurality of capacitors connected in parallel. And one end of each of the plurality of capacitors is connected to each input side of the plurality of switching elements via a parallel wiring, and each output side of the plurality of switching elements is connected in parallel. One end of this magnetizing coil is connected via wiring, and the other end of each of the plurality of capacitors is connected to the magnetizing coil and flywheel via parallel wiring. It is obtained so as to connect to the connection point of the Le diode.

  According to the present invention, the charging capacitor is composed of a plurality of capacitors connected in parallel, and each of the plurality of capacitors and the magnetizing coil are connected in parallel. The wiring resistance and the inductance can be reduced to 1 / number of parallel connections.

  In addition, according to the present invention, the maximum magnetization current I can be increased as much as the wiring resistance and inductance are reduced, so that the peak magnetic field can be increased, and thus even a magnet with a high coercive force can be satisfactorily used. Can be magnetized. Further, the time (maximum magnetizing current I) that can be obtained can be shortened by the amount that the maximum magnetizing current I can be increased, and heat generation can be suppressed.

  Hereinafter, with reference to FIG. 1, an example of an embodiment for implementing the magnetizing apparatus of the present invention (hereinafter referred to as “this example”) will be described. In FIG. 1, parts corresponding to those in FIG.

  In FIG. 1, one end of a commercial power supply 1 of 100 VAC or 200 VAC is a thyristor (SCR) that constitutes a phase control circuit that controls the phase of the commercial power supply according to the charging state of a charging capacitor 10 (capacitors 10a and 10b) described later. 2a and the thyristor 2b are respectively connected to the anode.

  The cathode of the thyristor 2a and the anode of the thyristor 2b are connected to the other end of the commercial power source 1 via the primary winding 3a of the step-up transformer 3, respectively. In this case, a control signal corresponding to the charging state of the charging capacitor 10 (capacitors 10a and 10b) is supplied to the respective gates G of the thyristors 2a and 2b, and the phase of the primary winding 3a of the step-up transformer 3 is controlled. The desired AC voltage is supplied.

  One end of the secondary winding 3b of the step-up transformer 3 is connected to one input terminal of a double-wave rectifier circuit 4 formed of a diode bridge, and the other end of the secondary-side winding 3b is the other end of the double-wave rectifier circuit 4. Connected to the input terminal.

  In this example, a plurality of (for example, two) capacitors 10 a and 10 b connected in parallel are connected between the positive output terminal and the negative output terminal of the both-wave rectifier circuit 4. The two capacitors 10a and 10b constitute the charging capacitor 10.

  In this example, the capacitors 10a and 10b are each set to 200 μF, for example, the capacitance of the parallel circuit is set to 400 μF, and charging is performed so that the voltage between both ends of the capacitors 10a and 10b is 1250V, for example.

  In this example, one end of the capacitor 10a is connected to the anode of a thyristor (SCR) 6 that constitutes a switch via the wiring 11a, and one end of the capacitor 10b is connected to the wiring 11a in parallel with the wiring 11b. Is connected to the anode of the thyristor 6 constituting the switch.

  The cathode of this thyristor 6 is connected to one end of a magnetizing coil 7 constituting a magnetizing yoke. Further, in this example, a series circuit of a resistor 12 having a predetermined resistance value R0 and a flywheel diode 8 is connected in parallel with the magnetizing coil 7.

  In this example, the other end of the capacitor 10a is connected to the connection point of the magnetizing coil 7 and the flywheel diode 8 via the wiring 11c, and the other end of the capacitor 10b is connected to the wiring 11c. It is connected to a connection point between the magnetizing coil 7 and the flywheel diode 8 through a wiring 11d provided in parallel.

  In this example, the wirings 11a, 11b, 11c, and 11d are configured by copper bars 15 having a height of 3 mm and a width of 30 mm as shown in FIG. The lengths of the wirings 11a, 11b, 11c, and 11d are as short as possible between the capacitors 10a and 10b and the magnetizing coil 7, and the resistance components of the wirings 11a, 11b, 11c, and 11d are as small as possible. To do.

  In addition, as shown in FIG. 2, in this example, a predetermined number of slits 15a for increasing the surface area are provided in the copper bar 15 constituting the wirings 11a, 11b, 11c, and 11d. Loss due to the skin effect on high frequency is reduced.

  In this example, when magnetizing a magnetized object, a plurality of (for example, two) capacitors connected in parallel with the magnetized object arranged in a predetermined relationship with respect to the magnetizing coil 7. Each of 10a and 10b is charged to 1250V, for example. Thereafter, a control signal is supplied to the gate G of the thyristor 6 to turn on the thyristor 6.

  At this time, a pulse current flows through the capacitor 10a → the wiring 11a → the thyristor 6 → the magnetizing coil 7 → the wiring 11c → the capacitor 10a, and a pulse magnetic field is generated in the magnetizing coil 7. At the same time, a pulse current flows through the capacitor 10b → the wiring 11b → the thyristor 6 → the magnetizing coil 7 → the wiring 11d → the capacitor 10b, a pulse magnetic field is generated in the magnetizing coil 7, and this magnetized object is magnetized. Can do.

  As described above, the charging capacitor 10 includes two capacitors 10a and 10b connected in parallel, and one end of each of the two capacitors 10a and 10b is connected via the parallel wirings 11a and 11b. It is connected to the anode of the thyristor 6. As a result, the wiring resistance and inductance of the parallel wirings 11a and 11b can be reduced to one half of the conventional one.

  The other end of each of the two capacitors 10a and 10b is connected to a connection point between the magnetizing coil 7 and the flywheel diode 8 via parallel wires 11c and 11d. Accordingly, the wiring resistance and inductance of the parallel wirings 11c and 11d can also be reduced to one half of the conventional one.

  For this reason, according to this example, the resistance component R1 and the inductance L1 of the above formulas (1) and (2) including the wiring from the charging capacitor 10 to the magnetizing coil 7, the thyristor 6 and the like are shown in FIG. Smaller than the conventional example. For this reason, since the maximum magnetization current I becomes larger from the equation (1), the peak magnetic field can also be made larger than in the conventional example.

  Further, according to this example, the resistance component R1 and the inductance L1 in the above formulas (1) and (2) including the wiring from the charging capacitor 10 to the magnetizing coil 7, the thyristor 6 and the like are compared with the conventional example. Get smaller. As a result, the time T until the maximum magnetization current I flows can be made shorter than that in the conventional example from the equation (2).

  In this example, a series circuit of a resistor 12 having a predetermined resistance value R0 and a flywheel diode 8 is connected in parallel to the magnetizing coil 7, and when the voltages of the capacitors 10a and 10b become approximately 0V, The flywheel diode 8 conducts, and a circulating current flows through the magnetizing coil 7, the flywheel diode 8 and the resistor 12.

This circulating current is naturally attenuated to zero by the resistance component R2 of the magnetizing coil 7, the resistance value R0 of the resistor 12, and the like. According to this example, since the resistor 12 having the resistance value R0 is connected in series to the flywheel diode 8, the time constant τ0 flowing through the flywheel diode 8 is
τ0 = L2 / R0 + R2
Thus, it becomes smaller than the conventional example. For this reason, the current flowing time can be reduced, and heat generation can be suppressed.

  Incidentally, in the conventional magnetizing apparatus of 400 μF specification as the charging capacitors 5 and 10, the resistance component R1 from the charging capacitor 5 to the magnetizing coil 7 is 6 mΩ, and the inductance L1 is 1.3 μH. The resistance component R1 from the charging capacitor 10 to the magnetizing coil 7 can be 3 mΩ and the inductance L1 can be about 0.9 μH.

  In this conventional magnetizing apparatus, when the charging capacitor 5 was charged at 1250 V, the maximum magnetizing current I was 20.4 KA and its rise time was 35 μS. In this example, when the capacitors 10a and 10b were charged at 1250 V, the maximum magnetization current I was 25 KA and the rise time was 29 μS.

  In the conventional magnetizing device of 200 μF specification as the charging capacitors 5 and 10, the resistance component R1 from the charging capacitor 5 to the magnetizing coil 7 is about 10 mΩ and the inductance L1 is about 2.1 μH. In the example, the resistance component R1 from the charging capacitor 10 to the magnetizing coil 7 can be set to 8 mΩ, and the inductance L1 can be set to about 1.0 μH.

  In this conventional magnetizing apparatus, when the charging capacitor 5 was charged with 2000 V, the maximum magnetizing current I was 19.8 KA and its rise time was 30 μS. In this example, when the capacitors 10a and 10b were charged with 2000 V, the maximum magnetization current I was 26 KA and the rise time was 22 μS.

  As described above, according to this example, since the charging capacitor 10 is constituted by the two capacitors 10a and 10b connected in parallel, the resistance component R1 from the charging capacitor 10 to the magnetizing coil 7 is constituted. Since the inductance L1 is smaller than that of the conventional example, the maximum magnetization current I can be increased, and the peak magnetic field can be increased accordingly.

  Therefore, it is possible to satisfactorily magnetize a NdFeB-based bonded magnet having a high holding force.

  Further, according to the present example, the resistance component R1 and the inductance L1 from the charging capacitor 10 to the magnetizing coil 7 can be reduced as compared with the conventional example, so that the time T until the maximum magnetizing current I is reduced. It can be smaller than the example. That is, since the time for passing the magnetizing current can be reduced, heat generation can be suppressed accordingly, and a small NdFeB-based bonded magnet can be magnetized satisfactorily.

  Further, in this example, since the resistor 12 having the resistance value R0 is connected in series with the flywheel diode 8, the time constant τ0 of the attenuation current flowing through the flywheel diode 8 becomes small, and heat generation can be suppressed accordingly. .

  FIG. 3 shows an example of another embodiment for carrying out the present invention. The embodiment shown in FIG. 3 will be described. In FIG. 3, portions corresponding to those in FIG. 1 are denoted by the same reference numerals, and redundant description thereof is omitted.

  In the embodiment shown in FIG. 3, one end of each of two capacitors 10a and 10b connected in parallel constituting the charging capacitor 10 is connected to a thyristor (SCR) that forms a switch via parallel wires 11a and 11b, respectively. ) Connected to the respective anodes of 6a and 6b.

  The respective cathodes of the thyristors 6a and 6b are connected to one end of the magnetizing coil 7 through parallel wirings 13a and 13b. Each of the wirings 13a and 13b is composed of a copper bar 15 having a slit 15a as shown in FIG. In FIG. 3, the other configurations are the same as those in FIG.

  In FIG. 3, when magnetizing an object to be magnetized, the object to be magnetized is arranged in a predetermined relationship with respect to the magnetizing coil 7, and the two capacitors 10a and 10b reach a voltage required for magnetization. When charged, a control signal is simultaneously supplied to the gates G of the thyristors 6a and 6b so that the thyristors 6a and 6b are simultaneously turned on.

  At this time, it can be easily understood that the same effect as the example of FIG. 1 can be obtained in the example of FIG. Further, in the example of FIG. 3, compared to the example of FIG. 1, the charging capacitor 10 is formed by connecting the cathodes of the thyristors 6 a and 6 b to one end of the magnetizing coil 7 via the parallel wirings 13 a and 13 b. The resistance component R1 and the inductance L1 from the magnetizing coil 7 to the magnetizing coil 7 can be reduced.

  Therefore, in the example of FIG. 3, the maximum magnetization current I can be increased by the amount that the resistance component R1 and the inductance L1 can be reduced as compared with the example of FIG. As a result, the peak magnetic field can be increased and good magnetization can be achieved, and the time T during which the maximum magnetization current I is obtained is shortened, and heat generation can be suppressed accordingly.

  FIG. 4 and FIG. 5 show examples of other embodiments for carrying out the present invention, respectively. 4 and FIG. 5 will be described. In FIG. 4 and FIG. 5, portions corresponding to those in FIG. 1 and FIG.

  4 and 5, the series circuit of the flywheel diode 8 and the resistor 12 connected in parallel to the magnetizing coil 7 in the embodiment example of FIGS. 1 and 3 is removed. 4 and 5, the thyristors 6, 6a and 6b are turned off when the voltages of the charging capacitors 10a and 10b become substantially 0V. The rest of the configuration is the same as that of the embodiment shown in FIGS.

  It can be easily understood that the same effects as those of the embodiment of FIGS. 1 and 3 can be obtained in the embodiment of FIGS.

  In the above example, the charging capacitor 10 is composed of two capacitors 10a and 10b connected in parallel. However, the charging capacitor 10 is composed of three or more capacitors connected in parallel. Needless to say, however.

  In the above example, the wirings 11a, 11b, 11c, 11d, 13a, and 13b are configured by the copper bar 15 having the slits 15a. Instead, the wirings 11a, 11b, 11c, 11d, 13a, and 13b may be configured by a captyre cable, a coaxial cable, or the like. Of course.

  It goes without saying that the present invention is not limited to the above-described examples, and various other configurations can be adopted without departing from the gist of the present invention described in the claims.

It is a block diagram which shows the example of the form for implementing this invention magnetizing apparatus. It is a notch perspective view which shows the example of a copper bar. It is a block diagram which shows the other example of the form for implementing this invention magnetizing apparatus. It is a block diagram which shows the other example of the form for implementing this invention magnetizing apparatus. It is a block diagram which shows the other example of the form for implementing this invention magnetizing apparatus. It is a block diagram which shows the example of the conventional magnetizing apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Commercial power supply, 2a, 2b, 6, 6a, 6b ... Thyristor (SCR), 3 ... Step-up transformer, 4 ... Double wave rectifier circuit, 7 ... Magnetization coil, 8 ... Flywheel diode, 10 ... Charging capacitor, 10a, 10b ... capacitor, 11a, 11b, 11c, 11d, 13a, 13b ... wiring, 12 ... resistor, 15 ... copper bar

Claims (7)

In a magnetizing apparatus having a charging capacitor that is charged to a high voltage via a step-up transformer and a magnetizing coil that is supplied with electric charge from the charging capacitor via a switch.
The charging capacitor is composed of a plurality of capacitors connected in parallel,
While connecting one end of each of the plurality of capacitors to the input side of the switch through a parallel wiring,
A magnetizing device, wherein the other end of each of the plurality of capacitors is connected to the magnetizing coil through a parallel wiring. A charging capacitor that is charged to a high voltage via a step-up transformer, a magnetizing coil that is supplied with electric charge from the charging capacitor via a switch, and connected in parallel to the magnetizing coil In a magnetizing device having a flywheel diode
The charging capacitor is composed of a plurality of capacitors connected in parallel,
While connecting one end of each of the plurality of capacitors to the input side of the switch through a parallel wiring,
A magnetizing device, wherein the other end of each of the plurality of capacitors is connected to a connection point of the magnetizing coil and the flywheel diode through a parallel wiring. In a magnetizing apparatus having a charging capacitor that is charged to a high voltage via a step-up transformer, and a magnetizing coil that is supplied with electric charge from the charging capacitor via a switch,
The switch is composed of a plurality of switching elements and the charging capacitor is composed of a plurality of capacitors connected in parallel.
One end of each of the plurality of capacitors is connected to each input side of the plurality of switching elements via a parallel wiring, and
Each output side of the plurality of switching elements is connected to one end of the magnetizing coil via a parallel wiring, and the other end of each of the plurality of capacitors is connected to the magnetizing coil via a parallel wiring. A magnetizing device characterized in that it is connected to the other end of the magnet. A charging capacitor that is charged to a high voltage via a step-up transformer, a magnetizing coil that is supplied with electric charge from the charging capacitor via a switch, and connected in parallel to the magnetizing coil In a magnetizing device having a flywheel diode
The switch is composed of a plurality of switching elements and the charging capacitor is composed of a plurality of capacitors connected in parallel.
One end of each of the plurality of capacitors is connected to each input side of the plurality of switching elements via a parallel wiring, and
Each output side of the plurality of switching elements is connected to one end of the magnetizing coil via a parallel wiring, and the other end of each of the plurality of capacitors is connected to the magnetizing coil via a parallel wiring. And a magnetizing device connected to the connection point of the flywheel diode. The magnetizing apparatus according to claim 1 or 2,
A magnetizing apparatus, wherein a parallel wire at one end of each of the plurality of capacitors and a parallel wire at the other end of each of the plurality of capacitors are wired with a copper bar, and a slit is provided in the copper bar. The magnetizing apparatus according to claim 3 or 4,
The parallel wiring at one end of each of the plurality of capacitors, the parallel wiring at the other end of each of the capacitors, and the parallel wiring at the output side of each of the plurality of switching elements are each wired with a copper bar and the copper bar A magnetizing device characterized in that a slit is provided. The magnetizing apparatus according to claim 2 or 4,
A magnetizing apparatus comprising a resistor having a predetermined resistance value connected in series to the flywheel diode.

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