JP2005294698A - Direct current reactor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a compact direct current reactor so as to allow one permanent magnet to generate a magnetic flux coping with a coil magnetic flux. <P>SOLUTION: A U-shaped core 10 is provided with lips 11, 12 formed inwardly from the tops of the legs 10a, 10b, and the lips 11, 12 are opposed to each other with a first space G1 configuring a magnetic gap located at the center line between the sections. L-shaped iron-cores 21, 22 and a permanent magnet 31 striding across the first space G1 of the U-shaped core 10 are retained with a second space G2 between the tops of legs 10a, 10b of the U-shaped core 10. An electromagnetic coil 5 generating the coil magnetic flux is wound around the U-shaped core 10. A permanent magnet path that is reversely directed to the coil magnetic path inside the U-shaped core 10 is formed by a biased magnetic flux of the permanent magnet 31. And, the distance of the first space G1 is shorter configured than that of the second space G2. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a DC reactor that is connected in series with a DC circuit of an AC / DC converter such as an inverter and smoothes harmonic components contained in a DC current, and in particular, effectively prevents demagnetization of a permanent magnet. Related to the DC reactor.

  Generally, when an excessive current flows through a coil due to a short-circuit current or a sudden load applied to an inverter output, a permanent magnet that is magnetically biased by a coil magnetic flux is demagnetized. Therefore, in order to prevent such demagnetization, it is necessary to prevent the coil magnetic flux from passing through the interior of the permanent magnet.

  The DC reactor that performs magnetic bias with a permanent magnet is described in Patent Document 1, Patent Document 2, and the like. The invention of the inductance element described in Patent Document 1 is such that a permanent magnet is inserted into a magnetic core gap to give a magnetic bias, thereby reducing a decrease in inductance. The invention described in Patent Document 2 provides a small inductance element suitable for smoothing a pulsating voltage or the like in a DC reactor that is also magnetically biased with a permanent magnet.

  Further, as a problem common to these inventions, there is a problem that demagnetization of the permanent magnet due to the coil magnetic flux occurs. As for the method for suppressing the demagnetization of the permanent magnet, Patent Documents 3 to 5 describe that the magnetic flux is bypassed by a magnetic gap in the magnetic bias type using, for example, a pair of permanent magnets.

Furthermore, in the outer iron type reactor as in Patent Document 6, permanent magnets are attached to both lip portions of the opening of the outer magnetic core so that the magnetic flux generated by the winding and the magnetic flux generated by the permanent magnet are branched at the lip portion. ing.
JP 54-32696 A JP-A-61-19098 JP 2003-318046 A Japanese Patent No. 3314908 Japanese Patent No. 3230647 JP 09-213546 A

  However, in the conventional DC reactor, there is a problem that the apparatus is easily increased in size because it is not a magnetic bias by a bias magnetic flux of only one permanent magnet. Further, it has been difficult to reliably prevent demagnetization of the permanent magnet.

  The present invention has been made in view of such a point, and an object thereof is to provide a compact DC reactor by generating a magnetic flux that opposes a coil magnetic flux with a single permanent magnet.

  The first DC reactor of the present invention does not include the first gap among the U-shaped core having lip portions facing each other via the first gap and the closed magnetic circuit formed in the U-shaped core. One end is provided at a position opposite to the both ends of the legs of the U-shaped core via the second gap, and a magnetic flux generating means for generating a predetermined magnetic flux in the closed magnetic path. Two L-shaped cores constituting a magnetic circuit so as to straddle the first gap with a permanent magnet sandwiched therebetween, and the gap between the second gaps is configured wider than the gap between the first gaps Thus, the magnetic flux of the magnetic flux generating means is prevented from passing through the permanent magnet.

  In the second DC reactor of the present invention, the magnetic flux generating means is a pair of electromagnetic coils that are respectively disposed on both leg portions of the U-shaped core and form a magnetic flux in the same direction in the closed magnetic path. Features.

  In addition, the third DC reactor of the present invention includes an E-type core having a pair of lip portions that oppose the side surfaces of the center leg through the first gap, and two closed magnetic circuits formed on the E-type core. The magnetic flux generating means is disposed at a position not including the first gap, and generates a predetermined magnetic flux in the closed magnetic path, and is opposed to the distal ends of both side legs of the E-type core via the second gap. A C-type core that is provided at a position and that forms two magnetic circuits so as to straddle the first gap by sandwiching a plate-like permanent magnet between the tip of the center leg of the E-type core, By configuring the interval of the second gap wider than the interval of the first gap, the magnetic flux of the magnetic flux generating means is prevented from passing through the permanent magnet.

  The fourth DC reactor of the present invention includes a U-shaped core having lip portions facing each other via a first gap, and the first gap among the closed magnetic circuit formed in the U-shaped core. Magnetic flux generating means that is disposed at a position not included and that generates a predetermined magnetic flux in the closed magnetic path, and is embedded in a position across the first gap in the lip portion via a second gap, and generates the magnetic flux. A plate-like permanent magnet that forms a magnetic flux in the U-shaped core that opposes the magnetic flux generated by the means, and by configuring the interval of the second gap wider than the interval of the first gap, The magnetic flux of the magnetic flux generation means is prevented from passing through the permanent magnet.

  The fifth direct current reactor of the present invention is characterized in that the magnetic flux generating means is an electromagnetic coil that is disposed at each of a plurality of locations of the U-shaped core and forms a magnetic flux in the same direction in the closed magnetic path. To do.

  Furthermore, the sixth DC reactor of the present invention includes a pair of E-type cores whose central legs are arranged to face each other via a first gap, and a pair of closed magnetic fields formed across the central legs of the E-type core. A magnetic flux generating means for generating a predetermined magnetic flux in each of the paths, and a second leg gap embedded in a position straddling the first gap of the central leg to counter the magnetic flux generated by the magnetic flux generating means. A rectangular parallelepiped permanent magnet that forms a magnetic flux in the pair of E-shaped cores, and the magnetic flux of the magnetic flux generating means is increased by making the interval of the second air gap wider than the interval of the first air gap. The permanent magnet is prevented from passing therethrough.

In the present invention, since the magnetic resistance of the magnetic path formed by the permanent magnet is configured to be larger than the magnetic resistance of the coil magnetic path, demagnetization of the permanent magnet can be reliably prevented.
Further, the difference in magnetoresistance is configured by adjusting the distance between the first and second air gaps, the cross-sectional area of each magnetic path, etc., and a magnetic flux that opposes the coil magnetic flux can be generated with only one permanent magnet. Therefore, there is an advantage that a compact DC reactor can be provided.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a side sectional view showing a DC reactor according to a first embodiment of the present invention.
The U-shaped core 10 is an iron core made of a thin plate laminated with soft magnetic materials, and includes lip portions 11 and 12 formed inwardly from the tips of the leg portions 10 a and 10 b of the U-shaped core 10. The lip portions 11 and 12 are opposed to each other with the first gap G1 constituting the magnetic gap interposed therebetween.

  L-shaped iron cores 21 and 22 are arranged on the U-shaped core 10 so that the ends and the ends of both leg portions 10a and 10b face each other. A rectangular parallelepiped permanent magnet 31 is sandwiched between the L-shaped iron cores 21 and 22. The permanent magnet 31 is magnetized integrally with the L-type iron core 21 side magnetized to the N pole, the L-type iron core 22 side magnetized to the S pole, and the respective magnetic pole faces in contact with the end faces of the L-type iron cores 21 and 22. It is configured.

  The U-shaped core 10 is wound with an electromagnetic coil 5 that generates a predetermined coil magnetic flux when current is supplied from the current source 4. Due to the coil magnetic flux of the electromagnetic coil 5, the U-shaped core 10 is closed by penetrating the first gap G1 in the direction from the lip portion 11 to the lip portion 12, as indicated by a solid arrow in the figure. A coil magnetic path is formed.

  The L-shaped iron cores 21 and 22 and the permanent magnet 31 configured in an integrated manner are in a form straddling the first gap G1 of the U-shaped core 10 and between the tips of the leg portions 10a and 10b of the U-shaped core 10. The gap G2 is held. As a result, a permanent magnet magnetic path opposite to the coil magnetic path is formed inside the U-shaped core 10 by the bias magnetic flux of the permanent magnet 31 as indicated by the broken arrow in the drawing.

FIG. 2 is a bird's-eye view of the DC reactor according to the first embodiment.
The U-shaped core 10 is formed so that both leg portions 10a and 10b and the lip portions 11 and 12 have the same cross-sectional area S1. Further, the cross-sectional area S2 of the L-shaped iron cores 21 and 22 is equal to the magnetic pole area of the permanent magnet 31 sandwiched therebetween, and is smaller than the cross-sectional area S1 of the U-shaped core 10. Further, the interval Lg2 between the second gaps G2 is formed wider than the interval Lg1 between the first gaps G1 in the U-shaped core 10. L1 is the magnetic path length proportional to the length of the U-shaped portion of the U-shaped core 10, L21 and L22 are the magnetic path lengths of the L-type iron cores 21 and 22, respectively, and L11 and L12 are the lip portions 11 and 12, respectively. Magnetic path length.

Here, L2 (= L21 + L22) is referred to as the total magnetic path length of the L-type iron cores 21 and 22, and L3 (= L11 + L12) is referred to as the total magnetic path length of the lip portions 11 and 12 of the U-type core 10.
FIG. 3 is an equivalent circuit diagram showing the magnetic resistance of the DC reactor.

  When the magnetomotive force (coil magnetomotive force) by the electromagnetic coil 5 provided at the bottom of the U-shaped core 10 is NI1, the closed magnetic path of the U-shaped core 10 includes the magnetic resistance R1 of the U-shaped portion and the lip portion. 11 and 12 and a magnetic resistance Rg1 of the first gap G1. Among these, the magnetic resistance R1 is proportional to the magnetic path length L1, the magnetic resistance R3 is proportional to the total magnetic path length L3, and the magnetic resistance Rg1 is proportional to the interval Lg1 of the first gap G1, It is inversely proportional to the cross-sectional area S1.

  When the magnetomotive force (permanent magnet magnetomotive force) of the permanent magnet 31 is NI2, the L-type iron cores 21 and 22 have a magnetic resistance R2 proportional to the total magnetic path length L2 and a magnetic resistance of the second gap G2. A magnetic path made of Rg2 is formed. Then, as will be described below, the magnetic resistances R1 and Rg1 of the coil magnetic path and the magnetic resistances R2 and Rg2 of the permanent magnet magnetic path are determined by the distance between the first and second gaps G1 and G2 and the respective magnetic paths. By operating the U-shaped core 10 to be formed and the cross-sectional areas S1 and S2 of the L-shaped iron cores 21 and 22, it can be set so that the coil magnetic flux does not pass through the permanent magnet.

  In FIG. 3, the coil magnetic flux due to the coil magnetomotive force NI1 passes through the path of magnetic resistance R1 → magnetic resistance R3 → magnetic resistance Rg1, and the magnetic flux due to the permanent magnet magnetomotive force NI2 travels along the path of magnetic resistance R2 → magnetic resistance Rg2 → magnetic resistance R1. If so, the following inequality holds.

R3 + Rg1 <R2 + Rg2 (1)
R1 <R3 + Rg1 (2)
Now, if the vacuum permeability is μ ₀ and the relative permeability of iron is μr, the permeability of the iron core is μ (= μ ₀ · μr), and the relative permeability of iron μr is about 10 ^3. For the permeability μ of the iron core,
μ >> μ ₀
There is a relationship.

  Here, since the left and right values of the above equation (2) are determined only by the shape of the U-shaped core 10, in order to satisfy the equation (2), if the U-shaped core 10 is designed in such a shape. Well, it can be dealt with independently of the L-type iron cores 21 and 22.

On the other hand, in the above equation (1), the magnetic resistances R3, Rg1, R2, and Rg2 are respectively
R3 = L3 / μ · S1
Rg1 = Lg1 / μ ₀ · S1
R2 = L2 / μ · S2
Rg2 = Lg2 / μ ₀ · S2
Therefore, in order to establish the expression (1), it is necessary to satisfy the following expressions (3) and (4) at the same time.

L3 / S1 <L2 / S2 (3)
Lg1 / S1 <Lg2 / S2 (4)
By the way, since the cross-sectional area S2 of the L-type iron cores 21 and 22 is configured to be smaller than the cross-sectional area S1 of the U-shaped core 10, the interval Lg2 of the second gap G2 is set here to be smaller than the interval Lg1 of the first gap G1. Since the magnetic resistance Rg2 becomes larger than the magnetic resistance Rg1 only by configuring widely, the above equation (4) is surely satisfied.

  As for the expression (3), if the width of the permanent magnet 31 is shortened or the height of the L-type iron cores 21 and 22 is increased in the configuration of the first embodiment shown in FIG. 1 and FIG. The total magnetic path length L3 of the lip portions 11 and 12 of the U-type core 10 is shorter than the total magnetic path length L2 of the L-type iron cores 21 and 22. This can be satisfied by setting the cross-sectional area S2 to be sufficiently small.

  Thus, in the DC reactor according to the first embodiment, by configuring the interval of the second gap G2 to be wider than the interval of the first gap G1, the above expressions (3) and (4) are satisfied simultaneously. The demagnetization of the permanent magnet 31 can be reliably prevented. Further, since the magnetic flux that opposes the coil magnetic flux is generated by only one permanent magnet 31, a compact DC reactor can be provided. Furthermore, by making the cross-sectional area S1 of the U-shaped core 10 larger than the cross-sectional area S2 of the L-shaped iron cores 21 and 22, the width of the permanent magnet 31 can be designed to be sufficiently large, and the L-shaped iron cores 21 and 22 can be designed. It is not necessary to increase the height.

Next, another DC reactor will be described. FIG. 4 is a side sectional view showing a DC reactor according to the second embodiment of the present invention.
As in the first embodiment, the DC reactor includes a U-shaped core 10, L-shaped iron cores 21 and 22 arranged so that the ends and ends of both leg portions 10a and 10b face each other, and Two electromagnetic coils 5a and 5b supplied with current from the current source 4 are wound around both leg portions 10a and 10b of the U-shaped core 10 and a rectangular parallelepiped permanent magnet 31 sandwiched therebetween.

  Even in this case, the first gap G1 is formed in the U-shaped core 10 in the direction from the lip portion 11 to the lip portion 12 as indicated by the solid line arrow in the figure due to the coil magnetic flux of the electromagnetic coils 5a and 5b. A closed coil magnetic path is formed through. Further, the permanent magnet magnetic path opposite to the coil magnetic path is formed inside the U-shaped core 10 by the bias magnetic flux of the permanent magnet 31 as indicated by the broken arrow in the drawing.

  Although detailed description is omitted here, as in the case of the first embodiment, by configuring the interval of the second gap G2 to be wider than the interval of the first gap G1, the above (3), (4 ) At the same time, the demagnetization of the permanent magnet 31 can be reliably prevented. Further, since the magnetic flux that opposes the coil magnetic flux is generated by only one permanent magnet 31, a compact DC reactor can be provided.

Next, another DC reactor will be described. FIG. 5 is a side sectional view showing a DC reactor according to a third embodiment of the present invention.
The DC reactor includes an E-type core 40, a C-type iron core 50, and a rectangular permanent magnet 32. The E-type core 40 is an iron core made of a thin plate laminated with a soft magnetic material, and has a first gap with respect to the central leg 40c inwardly from the tips of both side legs 40a and 40b of the E-type core 40. A pair of lip portions 41 and 42 are formed so as to oppose each other via G1.

  In the E-type core 40, a C-type iron core 50 is disposed so as to face the tips of the both side leg portions 40a, 40b. A rectangular permanent magnet 32 is sandwiched between the center leg 40 c of the E-type core 40 and the C-type iron core 50. The permanent magnet 32 has the C-type iron core 50 side magnetized to the S pole, the E-type core 40 side magnetized to the N-pole, and the magnetic pole surfaces of the C-type iron core 50 and the center leg 40c end surface of the E-type core 40. In a state of being in contact with each other.

  An electromagnetic coil 5 that generates a predetermined coil magnetic flux by being supplied with a current from the current source 4 is wound around the central leg 40 c of the E-type core 40. Due to the coil magnetic flux of the electromagnetic coil 5, inside the E-type core 40, as indicated by solid line arrows in the figure, the first gap G1 passes through the center leg 40c, and the lip 41 and the lip 42, respectively. Two sets of closed coil magnetic paths are formed.

  The C-type iron core 50 is held at a position facing the both side leg portions 40a and 40b of the E-type core 40 via the second gap G2. Then, the two magnetic fields straddle each of the first gaps G1 by the bias magnetic flux of the permanent magnet 32 sandwiched between the tips of the center legs 40c of the E-type core 40 as shown by the broken arrows in the figure. A circuit is constructed. These form a permanent magnet magnetic path opposite to the coil magnetic path inside the E-type core 40.

  The E-type core 40 is formed so that the leg portions 40a, 40b, 40c and the lip portions 41, 42 have the same cross-sectional area S1. The cross-sectional area S2 of the C-type iron core 50 is formed smaller than the cross-sectional area S1 of the E-type core 40. Further, the interval Lg2 between the second gaps G2 is formed longer than the interval Lg1 between the first gaps G1 in the E-type core 40.

  Therefore, in the third embodiment, as in the first and second embodiments described above, the magnetic resistances R1 and Rg1 of the two coil magnetic paths and the magnetic resistances R2 and Rg2 of the permanent magnet magnetic path are respectively obtained. The coil magnetic flux passes through the permanent magnet 32 by operating the distance between the first and second gaps G1 and G2 and the E-type core 40 and the cross-sectional areas S1 and S2 of the C-type iron core 50 where the magnetic paths are formed. Can be set not to. Moreover, the two permanent magnet magnetic paths are formed by the magnetic flux that opposes the coil magnetic flux by only one permanent magnet 32, and the interval of the second gap G2 is configured to be wider than the interval of the first gap G1. The expressions (3) and (4) are satisfied at the same time, and the demagnetization of the permanent magnet 32 can be reliably prevented.

  Next, a DC reactor according to the fourth embodiment will be described with reference to FIGS. 6 is a side sectional view showing a DC reactor according to a fourth embodiment of the present invention, and FIG. 7 is a bird's-eye view of the DC reactor shown in FIG.

  The U-shaped core 60 is an iron core made of a thin plate laminated with a soft magnetic material. The U-shaped core 60 includes inward lip portions 60c and 60d at the tips of the leg portions 60a and 60b, respectively. In the middle of the lip portions 60c and 60d, lip portions 61 and 62, and 63 and 64 branched into two are extended, and the lip portions 61 and 62, and 63 and 64 each constitute a magnetic gap. The first gap G1 is opposed to each other and is formed in parallel with each other in the vertical direction.

  Between the left and right lip portions 60c, 60d of the U-shaped core 60, a predetermined space portion sandwiched between the upper lip portions 61, 62 and the lower lip portions 63, 64 is formed. A plate-like permanent magnet 33 is sandwiched in the space portion. The permanent magnet 33 is magnetized to the N pole on the leg 60a side and magnetized to the S pole on the leg 60b side, and is held in a state in which each magnetic pole surface is separated from the U-shaped core 60 by, for example, a non-magnetic material. ing.

  The U-shaped core 60 is wound with an electromagnetic coil 5 that generates a predetermined coil magnetic flux when supplied with current from the current source 4. Due to the coil magnetic flux of the electromagnetic coil 5, the U-shaped core 60 penetrates through the first gap G1 from the lip portion 60c toward the lip portion 60d as shown by the solid line arrow in the drawing. A closed coil magnetic path is formed.

  In addition, the permanent magnet 33 is in a form straddling the first gap G1 formed between the lip portions 61 and 62, and 63 and 64, and between the tips of the leg portions 60a and 60b of the U-shaped core 60. Two gaps G2 are held. As a result, a permanent magnet magnetic path opposite to the coil magnetic path is formed inside the U-shaped core 60 by the bias magnetic flux of the permanent magnet 33, as indicated by a dashed arrow in the drawing.

  In FIG. 7, L6 is the magnetic path length proportional to the length of the U-shaped core 60 and the lip portions 60c and 60d, and L61 and L62 are the magnetic path lengths of the lip portion 61 and the lip portion 62, respectively. The total magnetic path length L7 is a magnetic path length (L7 = L61 + L62) proportional to the length obtained by adding the lip portions 61 and 62. Similarly, the magnetic path lengths of the lower lip portions 63 and 64 are equal to L61 and L62, respectively.

  The permanent magnet 33 in the U-shaped core 60 is held in a state in which the magnetic pole surfaces are separated from the lip portions 60c and 60d by the second gap G2. The interval Lg4 of the second gap G2 is formed to be larger than the interval Lg3 of the first gap G1 in the U-shaped core 60. The second gap G2 is provided in a cross section larger than the cross sectional area S63. The magnetic pole cross-sectional area S63 of the permanent magnet 33 is configured to have the same size as the cross-sectional areas S61 and S62 of the lip portions 61 and 62.

  As shown in FIG. 7, the U-shaped core 60 has both leg portions 60a, 60b and lip portions 60c, 60d having the same cross-sectional area S6. Further, the upper lip portions 61 and 62 and the lower lip portions 63 and 64 sandwiching the permanent magnet 33 have a cross-sectional area S61 and a cross-sectional area S62, respectively, and these cross-sectional areas S61 and S62 are substantially equal to each other. Is. The total cross-sectional area of the upper and lower lip portions 61 and 63 is S7 (= S61 + S62).

FIG. 8 is an equivalent circuit diagram showing the magnetic resistance of the DC reactor.
When the magnetomotive force (coil magnetomotive force) by the electromagnetic coil 5 provided at the bottom of the U-shape of the U-shaped core 60 is NI3, a magnetic resistance R6 of the U-shaped portion and a lip portion are used as a closed magnetic path of the U-shaped core 60. A combined magnetic resistance R7 of 61, 62 and 63, 64 and a combined magnetic resistance Rg3 of the two gaps G1 constitute a coil magnetic path. Of these, the magnetic resistance R6 is proportional to the magnetic path length L6 and inversely proportional to the cross-sectional area S6 of the U-shaped core 60. The combined magnetic resistance R7 is proportional to the total magnetic path length L7, the magnetic resistance Rg3 is proportional to the interval Lg3 of the first gap G1, and is inversely proportional to the total cross-sectional area S7 of the upper and lower lip portions 61 and 63.

  Further, when the magnetomotive force (permanent magnet magnetomotive force) of the permanent magnet 33 is NI4, the permanent magnet magnetic path is formed by a U-shaped magnetic resistance R6 and a total magnetic resistance Rg4 of the two gaps G2. Here, as will be described below, the magnitudes of the magnetic resistances R6, R7, Rg3 of the coil magnetic path and the magnitudes of the magnetic resistances R6, Rg4 of the permanent magnet magnetic path are the first and second gaps G1, G1, respectively. It is possible to set so that the coil magnetic flux does not pass through the permanent magnet by manipulating the interval G2 and the cross-sectional areas S6, S63, and S7 of the magnetic paths.

  In FIG. 8, when the coil magnetic flux by the coil magnetomotive force NI3 passes through the path of the magnetic resistance R6 → the combined magnetic resistance R7 → the combined magnetic resistance Rg3, and the magnetic flux by the permanent magnet magnetomotive force NI4 passes through the path of the magnetic resistance Rg4 → the magnetic resistance R6. Then, the following inequality holds.

R7 + Rg3 <Rg4 (5)
R6 <R7 + Rg3 (6)
Here, if the vacuum permeability is μ ₀ and the relative permeability of iron is μr, the permeability of the iron core is μ (= μ ₀ · μr), and the relative permeability μr of iron is about 10 ^3. Therefore, for the permeability μ of the iron core,
μ >> μ ₀
There is a relationship.

Here, the magnetic resistances R3, Rg1, R2, and Rg2 in the above formulas (5) and (6) are respectively
R6 = L6 / μ · S6
Rg3 = Lg3 / μ ₀ · S7
R7 = L7 / μ · S7
Rg4 = Lg4 / μ ₀ · S63
It becomes. Therefore, L7 / μr · S7 + Lg3 / S7 <Lg4 / S63 (7) for the above equation (5).
Can be rewritten.

In the equation (7), since the relative permeability μr of iron is about 10 ^3, the first term on the left side of the inequality can be ignored. Therefore, from equation (7), Lg3 / S7 <Lg4 / S63
Is guided. That is,
Lg3 ・ S63 <Lg4 ・ S7
Now, since the total sectional area S7 of the upper and lower lip portions 61 and 63 is larger than the magnetic pole sectional area S63 of the permanent magnet 33 (S63 <S7),
Lg3 <Lg4
It turns out that it is good.

  Therefore, in the DC reactor of the fourth embodiment, it can be understood that the condition of the above formula (5) is satisfied if the interval Lg3 of the first gap G1 is configured to be shorter than the interval Lg4 of the second gap G2.

In addition, for equation (6),
L6 · (S7 / S6) <L7 + μr · Lg3 (8)
Can be rewritten.

  The expression (8) can be satisfied by adjusting the design size of the U-shaped core 60 and the size of the first gap G1, and does not limit the size of the permanent magnet 33. .

  As described above, the DC reactor according to the fourth embodiment includes the U-shaped core 60 having the lip portions 60c and 60d facing each other via the first gap G1, and the closed magnetic circuit formed in the U-shaped core 60. Among these, the electromagnetic coil 5 which is arranged at a position not including the first gap G1 and generates a predetermined magnetic flux in the closed magnetic path, and the second gap G2 at a position straddling the first gap G1 of the lip portions 60c and 60d. And a plate-like permanent magnet 33 that forms a magnetic flux in the U-shaped core 60 that opposes the magnetic flux generated by the electromagnetic coil 5, and the interval of the second gap G <b> 2 is set to the first gap G <b> 2. By configuring the gap to be wider than the gap G <b> 1, the magnetic flux of the electromagnetic coil 5 is prevented from passing through the permanent magnet 33. Therefore, if the distance Lg3 of the first gap G1 and the total cross-sectional area S7 of the upper and lower lip portions 61 and 63 are determined so as to satisfy the above equation (8), the demagnetization of the permanent magnet 33 is ensured. Can be prevented. Further, since the magnetic flux that opposes the coil magnetic flux is generated by only one permanent magnet 33, a compact DC reactor can be provided. Furthermore, the width of the permanent magnet 33 can be designed to be sufficiently large according to the design dimension of the U-shaped core 60.

  The permanent magnet 33 sandwiched between the U-shaped cores 60 can be secured with a non-magnetic material except for both extreme surfaces, thereby securing a permanent magnet magnetic path. Needless to say, the cross-sectional area S6 of the U-shaped core 60 is determined by the number of turns of the coil 5, the current, the magnetomotive force of the permanent magnet 33, the magnetic permeability of the iron core, and the like.

Next, another DC reactor will be described. FIG. 9 is a side sectional view showing a DC reactor according to the fifth embodiment of the present invention.
As in the fourth embodiment, this DC reactor is a plate-shaped permanent magnet 33 sandwiched between U-shaped core 60 and inward lip portions 60c and 60d formed on both leg portions 60a and 60b. The two electromagnetic coils 5a and 5b supplied with current from the current source 4 are wound around both leg portions 60a and 60b of the U-shaped core 60.

  Even in this case, due to the coil magnetic flux of the electromagnetic coils 5a and 5b, the U-shaped core 60 penetrates the first gap G1 in the direction from the lip portion 60c to 60d as shown by the solid line arrow in the figure. Thus, a closed coil magnetic path is formed. Further, the permanent magnet magnetic path opposite to the coil magnetic path is formed inside the U-shaped core 60 by the bias magnetic flux of the permanent magnet 33 as shown by the broken arrow in the drawing.

  Therefore, also in the DC reactor of the fifth embodiment, by configuring the interval of the second gap G2 wider than the interval of the first gap G1, the above expressions (7) and (8) are satisfied simultaneously, The demagnetization of the permanent magnet 33 can be reliably prevented. Further, since the magnetic flux that opposes the coil magnetic flux is generated by only one permanent magnet 33, a compact DC reactor can be provided.

Next, another DC reactor will be described. FIG. 10 is a side sectional view showing a DC reactor according to the sixth embodiment of the present invention.
The DC reactor includes a core 70 in which two E-type cores 70 a and 70 b are combined from above and below, and a plate-like permanent magnet 34 sandwiched between the central space portions of the core 70. Each of the E-type cores 70a and 70b is an iron core made of a thin plate laminated with soft magnetic materials, and the left and right branch legs 71, 70 are sandwiched between the center legs 70c and 70d so that the permanent magnet 34 is sandwiched between them. 72, 73 and 74 are formed in parallel to each other. The branch legs 71 and 73 of the center leg 70c and the branch legs 72 and 74 of the center leg 70d are opposed to each other across the first gap G1 that forms a magnetic gap.

  A permanent magnet 34 is held in the space between the two center legs 70c and 70d of the core 70, the center leg 70c side is magnetized to the N pole, and the center leg 70d side is magnetized to the S pole. Each magnetic pole surface is held in a state of being separated from the U-shaped core 60 by the magnetic body. In addition, an electromagnetic coil 5 that generates a predetermined coil magnetic flux by being supplied with a current from the current source 4 is wound around the center legs 70 c and 70 d of the core 70. Due to the coil magnetic flux of the electromagnetic coil 5, the core 70 penetrates through the first gap G1 from the center leg 70c and is divided into left and right via the center leg 70d as indicated by solid arrows in the figure. Two sets of closed coil magnetic paths are formed.

  Further, the permanent magnet 34 is held with a second gap G2 between the center legs 70c of the E-type cores 70a and 70b and the tips of the 70d in a manner straddling the first gap G1. As a result, a permanent magnet magnetic path opposite to the coil magnetic path is formed inside the core 70 by the bias magnetic flux of the permanent magnet 33, as indicated by the broken arrow in the figure.

  The E-type cores 70a and 70b are formed so as to have the same cross-sectional area S7 including the central legs 70c and 70d. Further, the interval Lg4 between the second gaps G2 is formed wider than the interval Lg3 between the first gaps G1.

  The core 70 of this embodiment has a shape in which two U-shaped cores shown in the fourth embodiment are combined from the left and right, respectively, and coil magnets formed on the left and right by the electromagnetic coil 5 shared in the center. One permanent magnet 34 is provided for the road to constitute a DC reactor. Therefore, as apparent from comparison with the description of the fourth embodiment, by configuring the interval of the second gap G2 to be wider than the interval of the first gap G1, the above (7), (8) The expression can be satisfied at the same time, and the demagnetization of the permanent magnet 31 can be reliably prevented.

1 is a side sectional view showing a DC reactor according to a first embodiment of the present invention. It is a bird's-eye view of the direct-current reactor concerning a 1st embodiment. It is an equivalent circuit diagram which shows the magnetic resistance of the direct current reactor which concerns on 1st Embodiment. It is side surface sectional drawing which shows the DC reactor which concerns on 2nd Embodiment of this invention. It is side surface sectional drawing which shows the DC reactor which concerns on 3rd Embodiment of this invention. It is side surface sectional drawing which shows the DC reactor which concerns on 4th Embodiment of this invention. It is a bird's-eye view of the DC reactor which concerns on 4th Embodiment. It is an equivalent circuit diagram which shows the magnetic resistance of the direct current reactor which concerns on 4th Embodiment. It is side surface sectional drawing which shows the DC reactor which concerns on 5th Embodiment of this invention. It is side surface sectional drawing which shows the DC reactor which concerns on 6th Embodiment of this invention.

Explanation of symbols

4 Current source 5 Electromagnetic coil 10, 60 U-type core 10a, 10b, 60a, 60b Leg part 11, 12 Lip part 21, 22 L-type iron core 31, 32, 33, 34 Permanent magnet 40, 70a, 70b E-type core 50 C-type iron core 70 core

Claims (14)

A U-shaped core having lip portions facing each other via a first gap;
Magnetic flux generating means disposed in a position not including the first gap among the closed magnetic paths formed in the U-shaped core, and generating a predetermined magnetic flux in the closed magnetic path;
A magnetic circuit is configured so that one end is provided at a position facing the front ends of both leg portions of the U-shaped core via a second gap, and a plate-like permanent magnet is sandwiched between the other ends and the first gap is straddled. Two L-shaped cores to
The direct current reactor is characterized in that the magnetic flux of the magnetic flux generating means does not pass through the permanent magnet by configuring the second gap to be wider than the first gap.   2. The DC reactor according to claim 1, wherein the L-shaped core has a cross-sectional area through which the magnetic flux of the permanent magnet passes smaller than a cross-sectional area of the closed magnetic path formed in the U-shaped core.   2. The DC reactor according to claim 1, wherein the magnetic flux generating means is a pair of electromagnetic coils that are respectively disposed on both leg portions of the U-shaped core and that form a magnetic flux in the same direction in the closed magnetic path. An E-shaped core having a pair of lip portions that respectively oppose the side surfaces of the center leg through the first gap;
Of the two closed magnetic paths formed in the E-shaped core, a magnetic flux generating means disposed at a position not including the first gap and generating a predetermined magnetic flux in the closed magnetic path;
The E-core is provided at a position opposed to both ends of the leg portions of the E-type core via a second gap, and a plate-like permanent magnet is sandwiched between the E-core and the center leg of the E-type core so that the first gap is formed. A C-type core that forms two magnetic circuits so as to straddle;
The direct current reactor is characterized in that the magnetic flux of the magnetic flux generating means does not pass through the permanent magnet by configuring the second gap to be wider than the first gap.   5. The DC reactor according to claim 4, wherein the C-type core is configured such that a cross-sectional area through which the magnetic flux of the permanent magnet passes is smaller than a cross-sectional area of the closed magnetic path formed in the E-type core.   5. The DC reactor according to claim 4, wherein the magnetic flux generating means is an electromagnetic coil disposed on a central leg of the E-type core. A U-shaped core having lip portions facing each other via a first gap;
Magnetic flux generating means disposed in a position not including the first gap among the closed magnetic paths formed in the U-shaped core, and generating a predetermined magnetic flux in the closed magnetic path;
A plate-like permanent member that is embedded in a position across the first gap of the lip portion via a second gap and that forms a magnetic flux in the U-shaped core that opposes the magnetic flux generated by the magnetic flux generation means. A magnet,
The direct current reactor is characterized in that the magnetic flux of the magnetic flux generating means does not pass through the permanent magnet by configuring the second gap to be wider than the first gap.   8. The DC reactor according to claim 7, wherein the permanent magnet is configured such that a cross-sectional area of both poles facing the lip portion is smaller than a cross-sectional area of the lip portions facing each other in the U-shaped core. The U-shaped core has a ratio of a cross-sectional area of the lip portion facing each other to a cross-sectional area of the permanent magnet facing each other (S7 / S6), and the magnetic path length of the closed magnetic circuit formed in the U-shaped core. Is L6, the total magnetic path length of the lip portion is L7, the interval between the first gaps is Lg3, and the relative permeability of the U-shaped core is μr, the following inequality is satisfied. The DC reactor according to claim 7.
L6 · (S7 / S6) <L7 + μr · Lg3   8. The DC reactor according to claim 7, wherein the magnetic flux generating means is an electromagnetic coil that is disposed at each of a plurality of locations of the U-shaped core and forms a magnetic flux in the same direction in the closed magnetic path. A pair of E-shaped cores whose central legs are arranged opposite to each other via the first gap;
Magnetic flux generating means for generating a predetermined magnetic flux in each of a pair of closed magnetic paths formed across the center leg of the E-type core;
A rectangular parallelepiped that is embedded in a position across the first gap of the central leg via a second gap and that forms a magnetic flux in the pair of E-type cores against the magnetic flux generated by the magnetic flux generation means. With permanent magnets,
The direct current reactor is characterized in that the magnetic flux of the magnetic flux generating means does not pass through the permanent magnet by configuring the second gap to be wider than the first gap.   The DC reactor according to claim 11, wherein the permanent magnet is configured such that a cross-sectional area of both poles facing the central leg is smaller than a cross-sectional area of the central leg facing each other. The E-shaped core has a ratio of a cross-sectional area of the central leg facing each other to a cross-sectional area of the central leg opposed to both poles of the permanent magnet (S9 / S8), and the closed magnetic field formed in the E-shaped core. When the magnetic path length of the path is L8, the total magnetic path length of the central leg is L9, the distance between the first gaps is Lg5, and the relative permeability of the E-type core is μr, the following inequality is satisfied. It is comprised by these, The direct current reactor of Claim 11 characterized by the above-mentioned.
L8 · (S9 / S8) <L9 + μr · Lg5   The DC reactor according to claim 11, wherein the magnetic flux generation means is an electromagnetic coil disposed at a position including the first gap.

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