JP2017072481A - Magnetic flux detector, transformer, and inverter power supply apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a magnetic flux detector capable of directly detecting a magnetic flux passing through a transformer core from outside regardless of a specification such as magnitude of the magnetic flux passing through the transformer and the turn ratio of a coil.SOLUTION: A magnetic flux detector 1 detects a magnetic flux passing through a transformer core 21 having a gap 21c from outside of the transformer core 21, and includes an annular detector core 11 having a first gap 11c into which a magnetic flux leaked from the gap of the transformer core 21 flows and a detector 12 for detecting the magnetic flux passing through the detector core 11.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a magnetic flux detector that detects a magnetic flux passing through a transformer core from the outside of the transformer core, a transformer including the magnetic flux detector, and an inverter power supply device.

  The inverter power supply device is an inverter circuit that converts direct current supplied from a direct current power source into alternating current by switching control, a transformer that converts the converted alternating voltage value to a required voltage value, and rectifies the converted alternating current. And a rectifier circuit for supplying to an external load. The switching operation of the inverter circuit is PWM (Pulse Width Modulation) controlled by the control unit. Specifically, the control unit performs feedback control so that the direct current value supplied to the load becomes a required current value.

  In the inverter power supply device, the magnetic bias of the transformer is a problem. The demagnetization occurs due to various factors such as load fluctuations and variations in characteristics of switching elements. For example, in the case of an inverter power supply device for welding, the load frequently fluctuates greatly, so that bias magnetism is likely to occur. When the magnetism of the transformer core constituting the transformer proceeds and magnetic saturation occurs, an overcurrent flows through the inverter circuit and the switching element is damaged. As a technique for solving such a problem of magnetic demagnetization, various inverter power supply devices that can be controlled so as not to cause demagnetization, a demagnetization detector that detects demagnetization generated in a transformer, a transformer provided with a Hall element, etc. It has been known.

  Patent Document 1 discloses an inverter power supply apparatus that time-integrates a voltage induced in a detection coil wound around a transformer core and performs PWM control of the inverter circuit so that the average of the integrated values becomes zero. .

  Japanese Patent Application Laid-Open No. H11-260260 discloses a bias magnetism detector in which a U-shaped iron core that bypasses a part of magnetic flux passing through a transformer core is provided in the transformer core, and a detection coil is wound around the iron core.

  Patent Document 3 discloses an inverter power supply device that detects currents of a primary coil and a secondary coil of a transformer, and determines the presence or absence of bias using the current value and the turn ratio of each coil. When it is determined that the magnetism has occurred, the inverter power supply apparatus cancels the magnetism by controlling the switching element of the inverter circuit to be in an OFF state for a certain period.

  Patent Document 4 discloses a transformer configured to arrange a Hall element in a gap between transformer cores and detect a magnetic flux generated in the gap.

JP-A-8-187575 Japanese Patent Laid-Open No. 11-40429 JP 2012-10511 A JP 2004-96016 A

  However, in Patent Document 1, since the voltage of the detection coil wound around the transformer core is monitored, the magnetic flux generated in the transformer core is only detected indirectly or presumptively. There is a problem that the residual magnetism of the ceramic core, that is, the DC component of the magnetic flux cannot be detected, and the problem of the demagnetization is not sufficiently solved.

  Also in Patent Document 2, there is a problem similar to that of Patent Document 1 because it is a configuration that detects a magnetic bias using a detection coil wound around an iron core. In addition, there is a problem that it is difficult to increase the cross-sectional area of the iron core that bypasses a part of the magnetic flux passing through the transformer core. The magnetic flux passing through the iron core is very small with respect to the magnetic flux passing through the transformer core, and it is difficult to detect the magnetic flux.

  In Patent Document 3, since it is a configuration for determining the presence or absence of demagnetization using the turn ratio of the primary coil and the secondary coil, it is necessary to change the setting of the turn ratio for each transformer with different specifications. There's a problem. Moreover, since the voltage applied to the primary coil includes switching noise of the inverter circuit, there is a problem that it is impossible to detect the bias magnetism with high accuracy.

  In patent document 4, when the magnetic flux which passes along a transformer core is large, there exists a problem that the detection range of magnetic flux will be exceeded in general Hall element IC. In addition, a general transformer manufacturing process includes a process of improving insulation and mechanical strength by impregnating a varnish with a transformer core. Therefore, there is a need for a magnetic sensor that is not eroded by the varnish and that does not deform or change its characteristics even when dried at a high temperature of about 200 degrees. Further, it is necessary to attach the Hall element IC at the manufacturing stage of the transformer, and there is a problem that the manufacturing cost becomes high.

  The present invention has been made in view of such circumstances, and the object thereof is to directly apply the magnetic flux passing through the transformer core from the outside regardless of the specifications such as the magnitude of the magnetic flux passing through the transformer and the turns ratio of the coil. It is an object of the present invention to provide a magnetic flux detector, a transformer, and an inverter power supply device that can detect automatically.

  A magnetic flux detector according to the present invention is a magnetic flux detector for detecting a magnetic flux passing through a transformer core having a gap from the outside of the transformer core, and a gap into which a magnetic flux leaked from the gap of the transformer core flows. And a detection unit that detects a magnetic flux passing through the core.

In the present invention, a part of the magnetic flux passing through the transformer core leaks from the gap of the transformer core, and the leaked magnetic flux flows into the core through the gap. The detection unit detects a magnetic flux passing through the core. Since the permeability of the transformer core is larger than the permeability of air, the magnetic flux leaking from the gap of the transformer is generally very small. Even if the detector is placed near the gap, the transformer core The passing magnetic flux cannot be detected. However, since the magnetic flux detector according to the present invention includes a core having a gap, the magnetic flux leaking from the gap of the transformer core can be reduced by making the gap of the transformer core and the gap of the magnetic flux detector face each other. Can be increased. In addition, when making a space | gap oppose, the core of a magnetic flux detector and a transformer core may be made to contact, and you may make them separate. The detection unit can thus detect the magnetic flux leaking from the transformer core and flowing into the core. Since the detection unit directly detects the magnetic flux flowing into the core from the transformer core, it can also detect the DC magnetic flux remaining in the transformer core.
In addition, it is easier to design the magnitude of the magnetic flux flowing into the core to be within the detection range of the detection unit, compared to a configuration in which the magnetic flux of the transformer core is bypassed using a U-shaped iron core.
Furthermore, since the detection unit is not configured to detect the magnetic flux using the current flowing through the primary coil and the secondary coil of the transformer, the detection unit is concerned with the turn ratio of the primary coil and the secondary coil wound around the transformer core. Instead, the magnetic flux passing through the transformer core can be detected. Further, since the magnetic flux detector according to the present invention directly detects the magnetic flux, the switching noise of the inverter circuit does not become a problem.
Furthermore, even when the magnitude of the magnetic flux in the gap between the transformer cores exceeds the detection limit of the detector, a part of the magnetic flux passing through the transformer core flows into the core from the gap and flows into the core. Since the magnetic flux is detected outside the transformer, the magnetic flux of the transformer core can be detected. Further, since the detection unit is disposed outside the transformer core, it is not necessary to use a special magnetic sensor that can withstand the transformer manufacturing process, and the magnetic flux detector can be configured at low cost.
The shape of the gap between the cores is not particularly limited as long as the magnetic flux leaked from the transformer core flows into the core. For example, it is not necessary to completely cut off a part of the core to form a gap, and the gap may be partially formed by forming a groove-like or slit-like part in the core.

  In the magnetic flux detector according to the present invention, the core has a second gap in a portion different from the portion having the gap into which the magnetic flux flows, and the detection unit is arranged in the second gap, A configuration including a magnetic sensor that outputs a signal corresponding to the direction and magnitude of the magnetic flux passing through the second gap is preferable.

In the present invention, the magnetic sensor can output a signal corresponding to the direction and magnitude of the magnetic flux passing through the core, that is, a signal corresponding to the direction and magnitude of the magnetic flux passing through the transformer core. In addition, since the magnetic sensor arranged in the second gap of the core detects the magnetic flux passing through the core, smaller magnetic flux is detected compared to the configuration in which the detection winding is wound around the core. can do.
The shape of the second gap is not particularly limited as long as the magnetic flux passing through the core flows in and out of the second gap and passes through the magnetic sensor. For example, it is not necessary to completely cut off a part of the core to form the second gap, and the second gap may be partially formed by forming a groove-like or slit-like part in the core. .

  The transformer according to the present invention includes any one of the above-described magnetic flux detectors, a transformer core having a gap, and a non-magnetic material, and the gap between the transformer core and the gap between the cores into which the magnetic flux flows. And a support portion that supports the core so as to face each other.

In the present invention, the support portion supports the core of the magnetic flux detector so that the gap of the transformer core and the gap of the core of the magnetic flux detector face each other. The transformer can detect a magnetic flux passing through its own transformer core by a magnetic flux detector and output a signal corresponding to the direction and magnitude of the magnetic flux.
The shape of the gap between the transformer cores is not particularly limited as long as the magnetic flux leaks from the transformer core to the core of the magnetic flux detector. For example, it is not necessary to completely cut off a part of the transformer core to form a gap, and the gap may be partially formed by forming a groove-like or slit-like part in the transformer core.

  The transformer according to the present invention is preferably configured such that the support portion supports the core so that the positional relationship between the transformer core and the core can be changed.

  In the present invention, the positional relationship between the transformer core and the core can be changed. Accordingly, the positional relationship between the gap between the transformer cores and the gap between the cores can be changed, and the magnitude of the magnetic flux flowing into the core from the gap between the transformer cores can be adjusted. Therefore, the magnitude of the magnetic flux passing through the core can be adjusted to the detection range of the detection unit. Therefore, the magnetic flux passing through the transformer core can be accurately detected regardless of the magnitude of the magnetic flux passing through the transformer core.

  An inverter power supply device according to the present invention includes an inverter circuit that converts direct current to alternating current, a transformer core having a gap, and a transformer that transforms alternating current converted by the inverter circuit, and the transformer Based on the rectifier circuit that rectifies the transformed alternating current into direct current, the magnetic flux detector according to any one of the above that detects the magnetic flux passing through the transformer core, and the magnetic flux detected by the magnetic flux detector. And a control unit for controlling the operation of the inverter circuit.

  In the present invention, the magnetic flux of the transformer core constituting the inverter power supply device can be detected by the magnetic flux detector, and the control unit converts the operation of the inverter circuit into the magnetic flux detected by the magnetic flux detector. Can be controlled accordingly.

  In the inverter power supply device according to the present invention, when the direction of the magnetic flux passing through the core is a predetermined direction, the detection unit outputs a first signal having a predetermined polarity having a voltage level corresponding to the magnitude of the magnetic flux, When the direction of the magnetic flux is opposite to the predetermined direction, the control unit is configured to output a second signal of reverse polarity having a voltage level corresponding to the magnitude of the magnetic flux, and the control unit is configured to output the detection unit. Preferably, the switching of the inverter circuit is controlled so that the absolute values of the voltage levels of the first signal and the second signal output from the inverter are balanced.

  In the present invention, the detection unit outputs the first signal and the second signal corresponding to the direction and magnitude of the magnetic flux passing through the core, and the control unit outputs the first signal and the second signal output from the detection unit. The switching of the inverter circuit is controlled so that the absolute value of the voltage level of the signal is balanced. For example, when the absolute value of the first signal tends to be larger than the absolute value of the second signal, the control unit decreases the magnetic flux in a predetermined direction through the core or increases the magnetic flux in the direction opposite to the predetermined direction. To control switching. Similarly, when the absolute value of the second signal tends to be larger than the absolute value of the first signal, the control unit increases the magnetic flux in a predetermined direction passing through the core or the magnetic flux in the direction opposite to the predetermined direction. Control switching to decrease. A state in which the absolute values of the voltage levels of the first signal and the second signal are balanced corresponds to a state in which no bias is generated in the core of the transformer. Therefore, the control unit can control the switching of the inverter circuit so that no bias is generated in the transformer core.

  According to the present invention, the magnetic flux passing through the transformer core can be directly detected from the outside regardless of the specifications such as the magnitude of the magnetic flux passing through the transformer core and the turns ratio of the coil.

It is a perspective view which shows one structural example of the magnetic flux detector which concerns on this Embodiment 1. FIG. It is a front view which shows one structural example of the magnetic flux detector which concerns on this Embodiment 1. FIG. It is a circuit diagram which shows one structural example of a detection part. It is a perspective view which shows one structural example of the transformer which concerns on this Embodiment 2. FIG. It is the magnetic flux density distribution figure and graph which showed the magnetic flux produced | generated by the transformer core in the state which removed the magnetic flux detector. It is a perspective view which shows the transformer core and detector core in the state which made the direction of the gap | interval of a transformer core, and the direction of the 1st gap | interval of a detector core correspond. It is the magnetic flux density distribution figure and graph which showed the magnetic flux which flowed into the detector core in the state which made the gap | interval of the transformer core and the direction of the 1st gap | interval of a detector core correspond. It is the side view and top view which show one structural example of the support part which concerns on a modification. It is a perspective view which shows the transformer core and detector core in the state which inclined the direction of the gap | interval of a transformer core, and the 1st gap | interval of a detector core. It is the magnetic flux density distribution figure and graph which showed the magnetic flux which flowed into the detector core in the state which inclined the direction of the gap of a transformer core, and the 1st gap of a detector core. FIG. 6 is a circuit diagram illustrating a configuration example of an inverter power supply device according to a third embodiment. It is a circuit diagram which shows one structural example of a control part.

Hereinafter, the present invention will be described in detail with reference to the drawings illustrating embodiments thereof.
(Embodiment 1)
FIG. 1 is a perspective view showing a configuration example of the magnetic flux detector 1 according to the first embodiment, and FIG. 2 is a front view showing a configuration example of the magnetic flux detector 1 according to the first embodiment. A magnetic flux detector 1 according to Embodiment 1 of the present invention includes a flat, substantially rectangular parallelepiped casing 10 made of a nonmagnetic material such as aluminum, stainless steel, or resin, and the casing 10 has a gap between transformer cores 21. The detector core 11 into which the magnetic flux leaked from 21c flows in, and the detection part 12 which detects the magnetic flux which passes along this detector core 11 are accommodated.

  The detector core 11 includes a first detector core half 11a having a substantially U-shape when viewed from the front, and a second detector core half 11b having substantially the same shape as the first detector core half 11a. The first and second detector core halves 11a and 11b are opposed to each end of the first detector core half 11a and each end of the second detector core half 11b with a distance therebetween, It is fixed in the housing 10 in an annular shape as a whole. The detector core 11 is preferably composed of a soft magnetic material made of ferrite, magnetic metal, laminated steel plate, green powder compact, or the like. In the following, one end of the first detector core half 11a and one end of the second detector core half 11b are opposed to each other, and a separation site into which the magnetic flux leaked from the gap 21c of the transformer core 21 flows is provided. This is referred to as the first gap 11c. Further, the other end of the first detector core half 11a and the other end of the second detector core half 11b are opposed to each other, and a separation site where the detector 12 is disposed is referred to as a second gap 11d. .

  The housing 10 includes a plate portion 10a having a substantially rectangular shape when viewed from the front, a first side wall 10b and a second side wall 10c provided on the long side portion of the plate portion 10a, and a third side provided on the short side portion. A side wall 10d and a fourth side wall 10e are provided. The first gap 11c of the detector core 11 accommodated in the housing 10 is opposed to the first side wall 10b in the vicinity, and the second gap 11d is opposed to the second side wall 10c.

  A fixing portion 13 for fixing the magnetic flux detector 1 to the transformer (see FIG. 4) is formed at a suitable location on the outer surface of the plate portion 10a constituting the housing 10 from a nonmagnetic material. For example, the fixing portion 13 is formed at a substantially central portion in the longitudinal direction near the first side wall 10b of the plate portion 10a. The fixed portion 13 has a flat plate portion 13a that is substantially flush with the first side wall 10b, and a screw hole 13b is formed in the flat plate portion 13a.

  The detection unit 12 is disposed in the second gap 11d. The magnetic flux passing through the detector core 11 flows out from one end of the first detector core half 11a and the second detector core half 11b, passes through the detector 12, and flows into the other end. The detector 12 detects the magnetic flux passing through the second gap 11d, that is, the magnetic flux of the detector core 11.

FIG. 3 is a circuit diagram illustrating a configuration example of the detection unit 12. The detection unit 12 is provided in the second gap 11d, and includes a magnetic sensor 12a that outputs a magnetic flux signal corresponding to the direction and magnitude of the magnetic flux passing through the second gap 11d. The magnetic sensor 12a is, for example, a Hall IC having a Hall element. The magnetic sensor 12a has a pair of input terminals for allowing a control current to flow, and a pair of output terminals for outputting a voltage corresponding to the magnitude and direction of the magnetic flux applied to the magnetic flux sensor and the magnitude of the control current. One input terminal is connected to the power supply potential Vcc, and the other input terminal is connected to the ground potential via the constant current circuit 12b. The output terminal of the magnetic sensor 12a is connected to the input terminal of the amplifier 12c. The amplifier 12c amplifies the voltage output from the magnetic sensor 12a, and outputs the magnetic flux signal obtained by the amplification from the output terminal to the outside. A terminal or signal line (not shown) for outputting the magnetic flux signal to the outside is preferably provided on the second side wall 10c side in order to avoid the influence of the leakage magnetic flux from the transformer core 21.
The voltage level of the magnetic flux signal output and amplified from the output terminal of the magnetic sensor 12a configured as described above is proportional to the magnitude of the magnetic flux passing through the magnetic sensor 12a, in other words, the magnetic flux passing through the transformer core 21. Further, the polarity of the magnetic flux signal varies depending on the direction of the magnetic flux. The magnetic flux signal is a positive voltage when the direction of the magnetic flux passing through the detector core 11 is a predetermined direction, and is a negative voltage when the direction of the magnetic flux passing through the detector core 11 is opposite to the predetermined direction. The predetermined direction is, for example, the direction in which the magnetic flux flows from the top to the bottom in the second gap 11d in FIG.

  In the magnetic flux detector 1 configured as described above, if the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 are opposed to each other as shown in FIG. And a part of the magnetic flux flows into the detector core 11 from the gap 21c of the transformer core 21 through the first gap 11c. The magnetic flux flowing into the detector core 11 passes through the first and second detector core halves 11a and 11b, and a magnetic flux is also generated in the second gap 11d. Since the detection unit 12 is arranged in the second gap 11d, a magnetic flux signal having a polarity and a voltage level according to the direction and magnitude of the magnetic flux passing through the detector core 11, in other words, the magnetic flux passing through the transformer core 21. Output.

As described above, according to the magnetic flux detector 1 according to the first embodiment, the magnetic flux passing through the transformer core 21 can be directly detected from the outside of the transformer core 21. Specifically, the detection unit 12 of the magnetic flux detector 1 is a magnetic flux signal corresponding to the direction and magnitude of the magnetic flux passing through the detector core 11, that is, the polarity corresponding to the direction and magnitude of the magnetic flux passing through the transformer core 21. And a magnetic flux signal having a voltage level can be output.
In the magnetic flux detector 1 according to the first embodiment, the magnetic flux passing through the transformer core 21 can be directly detected from the outside of the transformer core 21 in a non-contact manner. It is also possible to detect the magnetic flux by bringing the detector core 11 into contact. However, it is preferable to detect the magnetic flux by separating the transformer core 21 and the detector core 11. This is because there is a problem of heat generation of the detector core 11.

  Further, the magnetic flux detector 1 can detect the magnetic flux of the transformer core 21 regardless of specifications such as the magnitude of the magnetic flux passing through the transformer 2 and the turns ratio of the coil.

  Furthermore, since the detection unit 12 directly detects the magnetic flux flowing from the transformer core 21 to the detector core 11, it can also detect the DC magnetic flux remaining in the transformer core 21.

  Furthermore, since the detection unit 12 or the magnetic sensor 12a is arranged outside the transformer core 21, the magnitude of the magnetic flux in the gap 21c of the transformer core 21 exceeds the detection limit of the detection unit 12. Even so, the magnetic flux of the transformer core 21 can be detected.

  Furthermore, since the detection unit 12 is arranged outside the transformer core 21, it is not necessary to use a special detection unit 12 or a magnetic sensor 12a that can withstand the manufacturing process of the transformer 2, and the magnetic flux detector 1 can be manufactured at low cost. Can be configured.

  Furthermore, since the magnetic sensor 12a disposed in the second gap 11d of the detector core 11 detects the magnetic flux passing through the core, a small magnetic flux can also be detected.

  In the first embodiment, the Hall element is described as the magnetic sensor 12a. However, the Hall element is only an example, and a magnetoresistive element, a Faraday element, or other known sensor whose characteristics change depending on the magnetic flux may be employed. .

  Moreover, although the example which accommodates the circuit which comprises the detection part 12 inside the housing | casing 10 was demonstrated, you may arrange | position circuits other than the magnetic sensor 12a which comprises the detection part 12 outside the housing | casing 10. FIG.

  Furthermore, although the example which arrange | positions the magnetic sensor 12a in the 2nd gap | interval 11d of the detector core 11 was demonstrated, if it is a position which can detect the magnetic flux which passes the detector core 11, the magnetic sensor 12a will be outside the 2nd gap | interval 11d. May be arranged. In this case, the detector core 11 may be formed in a substantially C shape having only the first gap 11c.

  Furthermore, the shape of the first gap 11 c of the detector core 11 is not particularly limited as long as the magnetic flux leaked from the magnetic flux detector 1 flows into the detector core 11. Alternatively, the first gap 11c may be partially formed by forming a groove-like or slit-like part in the part. Similarly to the first gap 11c, the shape of the second gap 11d is not particularly limited as long as the magnetic flux flows in and out of the second gap 11d of the detector core 11 and passes through the magnetic sensor 12a.

(Embodiment 2)
FIG. 4 is a perspective view illustrating a configuration example of the transformer 2 according to the second embodiment. The transformer 2 according to the second embodiment of the present invention includes the transformer core 21 and the magnetic flux detector 1 according to the first embodiment. The transformer core 21 includes a first transformer core half 21a that is substantially U-shaped in front view, and a second transformer core half 21b that is substantially the same shape as the first transformer core half 21a. The first and second transformer core halves 21b face each other with gaps 21c between the ends of the first transformer core halves 21a and the ends of the second transformer core halves 21b. It is fixed in an annular posture as a whole. The transformer core 21 is preferably composed of a soft magnetic material made of ferrite, magnetic metal, laminated steel plate, green powder compact, or the like. A primary coil 22 is wound around the first transformer core half 21a, and a secondary coil 23 is wound around the second transformer core half 21b.

  The gap 21c of the transformer core 21 is not particularly limited in the configuration of the transformer core 21 and the shape of the gap 21c as long as the magnetic flux leaks from the transformer 2 and flows into the detector core 11. For example, the transformer core 21 may be EI type or EE type, and magnetic flux leaks from the gap between the center leg of the EI type core and other gaps formed by interposing a spacer, to the detector core 11. You may comprise so that it may flow in. Further, the gap 21c may be partially formed by forming a groove-shaped or slit-shaped portion in the transformer core 21.

The transformer 2 supports the transformer core 21 and also supports the magnetic flux detector 1 so that the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 face each other. Is provided. The support portion 20 is formed of a nonmagnetic material such as aluminum, stainless steel, or resin, and includes a substantially rectangular substrate 20a that is fixed to the ground, a horizontal base, or the like. First and second support plates 20b and 20c that support the transformer core 21 so as to hold the transformer core 21 are formed substantially vertically at both ends of the substrate 20a. The transformer core 21 includes two gaps 21c. The first and second support plates 20b and 20c are fixed to the first and second support plates 20b and 20c so as to face each other in close proximity and face the gap 21c substantially horizontally. In addition, the shape of the support part 20 and the support attitude | position of the transformer 2 are examples, and are not limited to this.
The magnetic flux detector 1 is fixed to the outer surface of the second support plate 20c. For example, a screw is inserted through the hole 13b in a state where the first side wall 10b constituting the housing 10 of the magnetic flux detector 1 and the flat plate portion 13a of the fixing portion 13 are in surface contact with the outer surface of the second support plate 20c. The housing 10 is screwed to the second support plate 20c.

  FIG. 5 is a magnetic flux density distribution diagram and graph showing the magnetic flux generated in the transformer core 21 with the magnetic flux detector 1 removed. 5A is a magnetic flux density distribution diagram showing a result of analyzing the magnetic flux density generated when a current is passed through the primary coil 22 by a three-dimensional finite element method analysis, and FIG. 5B is a magnetic flux generated in the transformer core 21. It is a graph which shows the magnitude | size of a density. The horizontal axis of the graph shown in FIG. 5B indicates a position on a straight line passing through the centers of the two gaps 21c of the transformer core 21 as shown by a two-dot chain line in FIG. 5A. The vertical axis of the graph indicates the magnitude of the magnetic flux density on the straight line. The unit of magnetic flux density is Tesla. As shown in FIGS. 5A and 5B, in the state where the magnetic flux detector 1 is removed from the transformer core 21, the magnetic flux density passing through the transformer core 21 is about 120 mT, whereas the transformer core 21. The magnetic flux leaking to the outside through the gap 21c is small, and the magnetic flux density is about several mT.

FIG. 6 is a perspective view showing the transformer core 21 and the detector core 11 in a state where the direction of the gap 21c of the transformer core 21 and the direction of the first gap 11c of the detector core 11 are matched, and FIG. FIG. 6 is a magnetic flux density distribution diagram and graph showing magnetic flux flowing into the detector core 11 in a state in which the direction of the first gap 11c of the detector core 11 and the direction of the first gap 11c of the detector core 11 are matched. 7A and 7B are magnetic flux density distribution diagrams and graphs similar to those in FIG.
As shown in FIG. 6, when the gap 21 c of the transformer core 21 and the first gap 11 c of the detector core 11 are opposed to each other so that their orientations coincide with each other in a side view, they are shown in FIGS. 7A and 7B. Thus, it can be seen that the magnetic flux leaking from the gap 21c of the transformer core 21 increases, and the leaked magnetic flux flows into the detector core 11 through the first gap 11c. Further, when the magnetic flux flows into the detector core 11, the magnetic flux is also generated in the second gap 11 d of the detector core 11. A magnetic flux of about 20 mT is generated in the second gap 11d. The detector 12 detects the magnetic flux generated in the second gap 11d, and the magnetic flux detector 1 outputs a magnetic flux signal having a polarity and a voltage level corresponding to the direction and magnitude of the magnetic flux passing through the transformer core 21. Can do.

As described above, according to the transformer 2 according to the second embodiment, the magnetic flux detector 1 supported by the support unit 20 detects the magnetic flux passing through its own transformer core 21, and the detected magnetic flux direction and A magnetic flux signal indicating the magnitude can be output to the outside. The magnetic flux signal can be used for the detection of the demagnetization and various controls according to the detected demagnetization.
In addition, in this Embodiment 2, although the structure which arrange | positions the transformer core 21 and the detector core 11 in non-contact was illustrated, you may comprise so that the transformer core 21 and the detector core 11 may contact. However, as described in the first embodiment, a configuration in which the transformer core 21 and the detector core 11 are separated from each other is preferable.

(Modification)
In Embodiment 2 described above, an example in which the positional relationship between the transformer core 21 and the detector core 11 is fixed at a predetermined position has been described. However, the support unit 20 includes the magnetic flux detector 1 and the detector core 11. You may comprise so that the positional relationship of the transformer core 21 may be supported so that a change is possible.

  FIG. 8 is a side view and a plan view showing a configuration example of the support unit 120 according to the modification. The second support plate 120c according to the modified example has a screw hole 120d at a position substantially the same height as the gap 21c of the transformer core 21 in a side view. Preferably, when the magnetic flux detector 1 is fixed to the second support plate 120c using the screw hole 120d, the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 are in the same direction in a side view. The screw hole 120d is preferably formed so that the detector core 11 is positioned at the center in the width direction of the transformer core 21.

  The second support plate 120c has a plurality of other screw holes 120e and 120f that are the same height as the screw hole 120d in a side view and are equidistant from the screw hole 120d with the center in the width direction as the center. Have. The screw hole 120e is provided at a position that forms a predetermined first angle (for example, about 20 degrees) from a horizontal plane that passes through the screw hole 120d with the substantially central position in the width direction as a center. The second angle (for example, about 45 degrees) is provided.

  Further, a position adjusting plate 24 for adjusting the distance between the detector core 11 and the transformer core 21 can be exchanged between the second support plate 120c and the magnetic flux detector 1 as shown in FIG. 8B. Is intervened. In FIG. 8A, the illustration of the position adjustment plate 24 is omitted for convenience of drawing.

As shown in FIG. 8A, the magnetic flux detector 1 is fixed to the second support plate 120c using the screw hole 120d, and the centers of the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 are aligned. In the side view, the gap 21c and the first gap 11c can be aligned in the same direction. In this case, even if the magnitude | size of the magnetic flux which flows into the detector core 11 becomes the maximum and the magnetic flux which passes along the transformer core 21 is small, the said magnetic flux can be detected.
Further, by fixing the magnetic flux detector 1 to the second support plate 120c using the screw hole 120e and aligning the centers of the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11, in a side view, The gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 can make a first angle. Similarly, by using the screw hole 120f, the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 form a second angle in a side view. Thus, in the side view, the magnitude of the magnetic flux flowing from the transformer core 21 into the detector core 11 is adjusted by tilting the first gap 11c of the detector core 11 with respect to the gap 21c of the transformer core 21. It becomes possible to do.
Further, by replacing the interposed position adjusting plate 24 with another position adjusting plate 24 having a different thickness or attaching / detaching the position adjusting plate 24 as shown in FIG. The distance between the detector core 11 and the first gap 11c can be changed, and the magnitude of the magnetic flux flowing from the transformer core 21 into the detector core 11 can be adjusted.

  Hereinafter, it will be described that the magnetic flux passing through the second gap 11d of the detector core 11 changes by changing the positional relationship between the detector core 11 and the transformer core 21. In particular, it will be described that the magnetic flux in the second gap 11d changes depending on the inclination of the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11. Since it is easily predicted that the magnetic flux changes depending on the distance between the transformer core 21 and the detector core 11, detailed description is omitted.

  FIG. 9 is a perspective view showing the transformer core 21 and the detector core 11 in a state in which the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 are inclined. The detector core 11 and the transformer core 21 face each other in a positional relationship such that the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 form an angle of about 45 degrees in a side view. .

  FIG. 10 is a magnetic flux density distribution diagram and graph showing the magnetic flux flowing into the detector core 11 when the gap 21c of the transformer core 21 and the first gap 11c of the detector core 11 are in different directions. . 10A and 10B are the same magnetic flux density distribution diagram and graph as FIG. When the detector core 11 and the transformer core 21 are arranged to face each other in the positional relationship as shown in FIG. 9, the magnetic flux density passing through the transformer core 21 is as shown in FIGS. 10A and 10B. Although it flows into the detector core 11 from the gap 21c through the first gap 11c, it can be seen that the magnetic flux density passing through the second gap 11d is smaller than that in FIG. Specifically, comparing FIG. 7 and FIG. 10, the magnetic flux density in the second gap 11d is reduced by about 50%.

  As described above, according to the transformer 2 according to the modified example, by adjusting the positional relationship between the detector core 11 and the transformer core 21, the magnitude of the magnetic flux density passing through the second gap 11d is set to a required magnitude. Can be adjusted. Therefore, the amount of magnetic flux flowing into the detector core 11 can be adjusted, and the magnitude of the magnetic flux passing through the detector 12 can be adjusted. Therefore, the magnetic flux passing through the transformer core 21 can be detected with high accuracy regardless of the magnitude of the magnetic flux passing through the transformer core 21.

  In the modification, the method for adjusting the positional relationship between the detector core 11 and the transformer core 21 has been described. Needless to say, by adjusting the separation distance of the gap 21c of the transformer core 21 at the design stage, The magnitude of the magnetic flux flowing into the detector core 11 may be adjusted. Similarly, the magnitude of the magnetic flux flowing into the detector core 11 may be adjusted by adjusting the separation distance of the first gap 11 c of the detector core 11.

(Embodiment 3)
FIG. 11 is a circuit diagram illustrating a configuration example of the inverter power supply device 3 according to the third embodiment. The inverter power supply device 3 according to Embodiment 3 of the present invention is an insulating type and is used as, for example, a welding power source. The inverter power supply device 3 includes a control unit 30, a first rectifier circuit 31 and a smoothing capacitor C1, an inverter circuit 32, a transformer 2, a second rectifier circuit 33, a DC reactor 34 and a smoothing capacitor C2, and an output current. And a detector 35.

  The first rectifier circuit 31 is, for example, a diode bridge circuit. The diode bridge has a circuit configuration in which three series circuits each including two forward-connected diodes (not shown) are arranged in parallel. The input terminal of the first rectifier circuit 31 is connected to the three-phase AC power supply 4, and each terminal of the smoothing capacitor C <b> 1 is connected to the output terminal pair of the first rectifier circuit 31. The first rectifier circuit 31 performs full-wave rectification on the alternating current supplied from the three-phase alternating current power supply 4 and outputs the direct current smoothed by the smoothing capacitor C <b> 1 to the inverter circuit 32.

  The inverter circuit 32 is a circuit that converts the direct current rectified and smoothed by the first rectifier circuit 31 and the capacitor C1 into a high frequency alternating current and outputs the alternating current to the transformer 2, and the first to fourth switching elements 32a and 32b. , 32c, 32d. The first to fourth switching elements 32a, 32b, 32c, and 32d are power devices such as IGBT (Insulated Gate Bipolar Transistor) or MOSFET (Metal-Oxide-Semiconductor Field Effect Transistor). Hereinafter, in the present embodiment, the first to fourth switching elements 32a, 32b, 32c, and 32d will be described as IGBTs. In addition, the 1st thru | or 4th switching element 32a, 32b, 32c, 32d is provided with the free-wheeling diode which is not shown in figure. The collectors of the first and third switching elements 32a and 32c are connected to the positive terminal of the smoothing capacitor C1. The emitters of the first switching element 32a and the third switching element 32c are connected to the collectors of the second and fourth switching elements 32b and 32d, respectively, and the emitters of the second and fourth switching elements 32b and 32d are on the negative electrode side of the smoothing capacitor C1. Connected to the terminal.

  The transformer 2 transforms the alternating voltage value output from the inverter circuit 32 to a required voltage value, and outputs the transformed alternating current to the second rectifier circuit 33. The transformer 2 includes a primary coil 22 and a secondary coil 23 that are wound around a transformer core 21 and are magnetically coupled. The configuration of the transformer 2 is as described in the second embodiment. The transformer 2 detects a magnetic flux passing through the transformer core 21 and outputs a magnetic flux signal corresponding to the detected magnetic flux to the control unit 30. 1 is provided. One end of the primary coil 22 is connected to the emitter of the first switching element 32a and the collector of the second switching element 32b, and the other end of the primary coil 22 is connected to the emitter of the third switching element 32c and the collector of the fourth switching element 32d. ing.

  The second rectifier circuit 33 rectifies the alternating current output from the transformer 2, and the rectified direct current is smoothed by the smoothing capacitor C <b> 2 and the direct current reactor 34 and output from the output terminal to the load 5. The load 5 is an arc load related to welding, for example. The second rectifier circuit 33 is a full-wave rectifier circuit using a center tap, for example. One end of a DC reactor 34 is connected to the positive output terminal of the second rectifier circuit 33. Each terminal of the smoothing capacitor C <b> 2 is connected to the other end of the DC reactor 34 and the negative output terminal of the second rectifier circuit 33, and each terminal of the smoothing capacitor C <b> 2 is connected to the output terminal of the inverter power supply device 3.

  The output current detection unit 35 is connected to, for example, the negative output terminal of the second rectifier circuit 33, detects the current flowing from the inverter power supply device 3 to the load 5, and controls the output current value signal indicating the detected current value. It is a circuit that outputs to the unit 30.

  The control unit 30 is a circuit that performs PWM control of on / off of the first to fourth switching elements 32a, 32b, 32c, and 32d that constitute the inverter circuit 32. Specifically, the control unit 30 alternates between a conductive state in which the first and fourth switching elements 32a and 32d are turned on and a conductive state in which the second and third switching elements 32b and 32c are turned on. By switching, an alternating current is output from the inverter circuit 32. The control unit 30 receives the output current value signal output from the output current detection unit 35 and the magnetic flux signal output from the magnetic flux detector 1. The control unit 30 controls the first to fourth switching elements 32a, 32b, and 32c so that the voltage level of the output current value signal output from the output current detection unit 35 becomes a voltage according to the set required current value. , 32d is increased or decreased. In addition, the control unit 30 sets the ON time of the first and fourth switching elements 32 a and 32 d and the second and third switching elements 32 b and 32 c so that the positive and negative of the magnetic flux signal output from the magnetic flux detector 1 are balanced. Increase or decrease the on-time. That is, the control unit 30 adjusts the balance of the on-time of the first to fourth switching elements 32a, 32b, 32c, and 32d so that the bias magnetism generated in the transformer core 21 is eliminated.

  FIG. 12 is a circuit diagram illustrating a configuration example of the control unit 30. The control unit 30 includes a reference signal oscillation circuit 30a, a reference signal modulation circuit 30b, an integration circuit 30c, a pulse width modulation circuit 30d, a PID (Proportional-Integral-Derivative) compensator 30e, an output current setting circuit 30f, a synchronization circuit 30g, and a drive. A circuit 30f is provided.

The reference signal oscillation circuit 30a is a circuit that outputs a triangular wave reference signal to the reference signal modulation circuit 30b and the synchronization circuit 30g with a period twice as long as the ON / OFF period of the inverter circuit 32. The integration circuit 30c is a circuit that integrates the magnetic flux signal output from the magnetic flux detector 1 and outputs an integration signal obtained by integration to the reference signal modulation circuit 30b.
Here, when the first and fourth switching elements 32a and 32d are in the ON state, the direction of the magnetic flux passing through the detector core 11 is a predetermined direction, and the magnetic flux signal becomes a positive voltage, and the second and third switching elements 32b and 32c. Is in the ON state, the direction of the magnetic flux passing through the detector core 11 is opposite to the predetermined direction, and the magnetic flux signal is a negative voltage.
The sign and magnitude of the integration signal correspond to the average of the direction and magnitude of the magnetic flux passing through the transformer core 21. When the voltage level of the integration signal is biased to the positive side or the negative side, This means that there is a bias. The reference signal modulation circuit 30b performs modulation by subtracting and adding an integral signal from the reference signal, and outputs a subtraction modulation reference signal obtained by modulation and an addition modulation reference signal to the pulse width modulation circuit 30d.

  A PID compensator 30e is connected to the pulse width modulation circuit 30d, and an output current setting circuit 30f and an output current detector 35 are connected to the PID compensator 30e. The output current setting circuit 30f outputs a target current value signal having a voltage level corresponding to the set target current value to the PID compensator 30e. The PID compensator 30e compensates so that the output current value becomes the target current value based on the output current value signal output from the output current detector 35 and the target current value signal output from the output current setting circuit 30f. An output current compensation signal for calculating the output current is calculated, and the calculated output current compensation signal is output to the pulse width modulation circuit 30d. The pulse width modulation circuit 30d compares the subtraction modulation reference signal with the output current compensation signal, and outputs a subtraction pulse width modulation signal corresponding to the comparison result to the synchronization circuit 30g. Specifically, when the voltage level of the subtraction modulation reference signal is higher than the voltage level of the output current compensation signal, the pulse width modulation circuit 30d outputs a high level subtraction pulse width modulation signal, and the voltage of the subtraction modulation reference signal When the level is lower than the voltage level of the output current compensation signal, a low level subtracted pulse width modulation signal is output. Similarly, the pulse width modulation circuit 30d compares the addition modulation reference signal with the output current compensation signal, and outputs an addition pulse width modulation signal corresponding to the comparison result to the synchronization circuit 30g.

  The synchronization circuit 30g outputs a subtracted pulse width modulation signal to the drive circuit 30f at a timing to turn on the first and fourth switching elements 32a and 32d in accordance with the reference signal output from the reference signal oscillation circuit 30a. The addition pulse width modulation signal is output to the drive circuit 30f at the timing when the third switching elements 32b and 32c are turned on.

  When the subtraction pulse width modulation signal is input from the synchronization circuit 30g, the drive circuit 30f outputs an ON signal to the gates of the first and fourth switching elements 32a and 32d during a period when the subtraction pulse width modulation signal is at a high level. . Similarly, when the addition pulse width modulation signal is input from the synchronization circuit 30g, the drive circuit 30f is turned on to the gates of the second and third switching elements 32b and 32c during the period when the addition pulse width modulation signal is at a high level. Is output.

As described above, according to the inverter power supply device 3 according to the third embodiment, the magnetic flux of the transformer core 21 constituting the inverter power supply device 3 can be detected by the magnetic flux detector 1, and the control unit 30 is an inverter circuit. The operation of 32 can be controlled according to the magnetic flux detected by the magnetic flux detector 1.
Specifically, the control unit 30 performs switching control of the inverter circuit 32 so that the integral value of the magnetic flux signal output from the magnetic flux detector 1 becomes zero, so that the positive voltage magnetic flux signal and the negative voltage Balance the flux signal. More specifically, the longer the period during which the integral value is positive, the shorter the on period of the first and fourth switching signals, and the longer the on period of the second and third switching signals. The magnetic flux in a predetermined direction generated in the ceramic core 11 is suppressed. Conversely, the longer the period during which the integral value is negative, the longer the on-period of the first and fourth switching signals, and the shorter the on-period of the second and third switching signals, and the transformer core 21 and the detector core 11. The magnetic flux generated in the direction opposite to the predetermined direction is suppressed. In short, the ON periods of the first to fourth switching elements 32a, 32b, 32c, and 32d can be balanced so as to suppress the demagnetization.
Therefore, the control unit 30 can control the switching of the inverter circuit 32 so that no bias is generated in the transformer core 21.

  Further, since the magnetic flux detector 1 directly detects the magnetic flux passing through the transformer core 21, the magnetic flux detection accuracy is not lowered by the switching noise of the inverter circuit 32. Therefore, the inverter power supply device 3 can accurately detect the magnetic bias of the transformer 2 and perform switching control of the inverter circuit 32 so that the magnetic bias is suppressed.

  In the third embodiment, an example in which the control unit 30 is configured mainly using an analog circuit has been described. However, the configuration of the control unit 30 is an example, and the control unit 30 is configured by combining a microcomputer or a microcomputer and an analog circuit. It may be configured.

Moreover, although the example which performs switching control of the inverter circuit 32 so that the integral value of a magnetic flux signal became zero was demonstrated, it is an example to the last and the control method of the control part 30 is not limited to this. For example, the control unit 30 may perform switching control of the inverter circuit 32 such that the difference between the absolute value of the positive magnetic flux signal and the absolute value of the negative magnetic flux signal is less than a threshold value.
Further, the control content of the control unit 30 according to the present invention using the magnetic flux signal is not limited to the switching control, and includes control that stops the output of the inverter power supply device 3 when the magnetic bias is detected. .

  Further, in the third embodiment, the inverter power supply device 3 for welding has been described. However, the use of the inverter power supply device 3 according to the present invention is not particularly limited, and the power source for the plasma generator and other arbitrary uses. You may apply to.

  It should be thought that embodiment disclosed this time is an illustration and restrictive at no points. The scope of the present invention is defined by the terms of the claims, rather than the meanings described above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Magnetic flux detector 2 Transformer 3 Inverter power supply device 4 Three-phase alternating current power supply 5 Load 10 Case 11 Detector core 11c 1st gap | interval 11d 2nd gap | interval 12 Detection part 12a Magnetic sensor 13 Fixed part 20,120 Support part 21 Transformer Core 21c Gap 22 Primary coil 23 Secondary coil 24 Position adjustment plate 30 Control unit 31 First rectifier circuit 32 Inverter circuit 33 Second rectifier circuit 34 DC reactor 35 Output current detector

Claims (6)

A magnetic flux detector for detecting a magnetic flux passing through a transformer core having a gap from the outside of the transformer core,
An annular core having a gap into which magnetic flux leaked from the gap in the transformer core flows;
A magnetic flux detector comprising: a detection unit that detects magnetic flux passing through the core. The core is
Having a second gap at a location different from the location having the gap into which the magnetic flux flows,
The detector is
The magnetic flux detector according to claim 1, further comprising a magnetic sensor arranged in the second gap and outputting a signal corresponding to the direction and magnitude of the magnetic flux passing through the second gap. The magnetic flux detector according to claim 1 or 2,
A transformer core having a gap;
A transformer comprising a non-magnetic material, and a support portion that supports the core such that a gap between the transformer core and a gap between the cores into which magnetic flux flows are opposed to each other. The support part is
The transformer according to claim 3, wherein the core is supported so that a positional relationship between the transformer core and the core can be changed. An inverter circuit for converting direct current to alternating current;
A transformer having a transformer core having a gap, and transforming an alternating current converted by the inverter circuit;
A rectifier circuit that rectifies alternating current transformed by the transformer into direct current;
The magnetic flux detector according to claim 1 or 2, wherein a magnetic flux passing through the transformer core is detected.
An inverter power supply apparatus comprising: a control unit that controls the operation of the inverter circuit based on the magnetic flux detected by the magnetic flux detector. When the direction of the magnetic flux passing through the core is a predetermined direction, the detection unit outputs a first signal having a predetermined polarity having a voltage level corresponding to the magnitude of the magnetic flux, and the direction of the magnetic flux is opposite to the predetermined direction. The second signal having a voltage level corresponding to the magnitude of the magnetic flux is output.
The controller is
The inverter power supply device according to claim 5, wherein switching of the inverter circuit is controlled so as to balance the absolute values of the voltage levels of the first signal and the second signal output from the detection unit.

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