JP5741706B2 - Converter transformer, transformer module and wireless power transmission system - Google Patents

Description

  The present invention relates to a converter transformer, a transformer module, and a wireless power transmission system having an open magnetic core around which a primary winding and a secondary winding are wound.

  In recent years, when charging an electronic device such as a mobile phone or a mobile PC, wireless power transmission that can be charged only by installing the electronic device in the charging device has been performed in order to eliminate the trouble of connecting a charging cable to the electronic device. Proposed. In this wireless power transmission, a transformer is used to increase the voltage at the coupling portion between the power transmitting device side and the power receiving device side, and it is necessary to efficiently transmit power while suppressing noise generated in the transformer. For this reason, a technique is known in which a metal electrostatic shield is provided between a primary coil and a secondary coil of a transformer used in a power supply circuit to suppress noise generated in the transformer (see, for example, Patent Document 1). .

JP 60-260119 A

  By the way, recent cellular phones and the like have been reduced in size, and therefore, it is desired to reduce the size of power supply circuits and the like mounted on electronic devices. However, in Patent Document 1 using a transformer having a closed magnetic circuit structure, it is difficult to reduce the core size, resulting in a problem that the transformer becomes large. Therefore, it is conceivable to use a transformer with an open magnetic circuit structure. However, when the transformer with an open magnetic circuit structure is covered with an electrostatic shield, the electrostatic shield leaks away from the transformer due to the magnetic flux leaking from the transformer. A working eddy current is generated. As a result, the inductance is reduced and the Q value of the transformer is lowered, which causes a problem that efficient power transmission cannot be performed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a converter transformer, a transformer module, and a wireless power transmission system that can suppress a decrease in Q value, electrostatically shield, and further realize downsizing.

  A converter transformer according to the present invention includes a magnetic core that forms an open magnetic path, a winding wound around the magnetic core, and an electrostatic shield that covers the magnetic core around which the winding is wound. The electrostatic shield is characterized in that one or more notches are formed.

  In this configuration, the transformer can be miniaturized by using an open magnetic path type magnetic core. Further, the eddy current generated in the electrostatic shield due to the leakage magnetic flux is less likely to flow in comparison with the case where the notch portion is not formed in the electrostatic shield. As a result, it is possible to prevent a problem that the transformer magnetic flux is canceled by the magnetic flux generated by the eddy current and the transformer Q value is lowered.

  In the converter transformer according to the present invention, the winding has a primary winding and a secondary winding wound adjacently, and one of the primary winding and the secondary winding is on a higher voltage side than the other. The configuration is preferably.

  In this configuration, even if the primary winding or the secondary winding has a high voltage, the radiated electric field can be blocked by the electrostatic shield.

  In the converter transformer according to the present invention, it is preferable that the electrostatic shield has at least three surfaces along the axial direction of the magnetic core, and a notch is formed on each of the three surfaces.

  With this configuration, it is difficult for eddy currents to flow on each surface, thereby preventing the problem that the transformer magnetic flux is canceled out by the magnetic flux generated by the eddy currents and the transformer Q value is reduced.

  The converter transformer according to the present invention may further include a surrounding portion having one surface that covers the magnetic core together with the three surfaces of the electrostatic shield.

  In this configuration, electrostatic shielding can be performed more efficiently by covering the magnetic core using a surrounding portion of a member different from the electrostatic shield.

  The converter transformer which concerns on this invention WHEREIN: The structure further provided with the ferrite member provided between the said electrostatic shield and the said coil | winding may be sufficient.

  With this configuration, the leakage magnetic flux can be made difficult to enter the electrostatic shield. Further, since the magnetic shield is provided by the ferrite member, the Q value of the transformer is improved.

  In the converter transformer according to the present invention, it is preferable that the notch is a slit extending in a direction orthogonal to the axial direction of the magnetic core.

  In this configuration, by using a slit, it is possible to make it difficult to flow eddy current with a simple configuration.

  In the converter transformer according to the present invention, it is preferable that the slit is formed inward from the peripheral edge portion on each of the three surfaces.

  In this configuration, it is possible to make it difficult for eddy currents to flow through the electrostatic shield by forming a slit that is not closed in the electrostatic shield.

  In the converter transformer according to the present invention, it is preferable that a plurality of the slits are formed along the axial direction of the magnetic core, and the width of the slits in the axial direction is shorter than the distance between adjacent slits.

  In this configuration, since the area of the surface of the electrostatic shield on which the slit is formed can be sufficient, electrostatic shielding can be effectively performed.

  In the converter transformer according to the present invention, the electrostatic shield has two comb-shaped members, the two comb-shaped members are opposed to each other, and the respective comb teeth are inserted into each other so as to form the slit therebetween. But you can.

  In this configuration, since the slit is formed by two members, the slit width is easy to adjust.

  According to the present invention, it is possible to reduce the size of the converter transformer, and to take EMC (Electro-Magnetic Compatibility) measures by shielding noise with an electrostatic shield without reducing the Q value of the transformer.

The side view of the transformer module which concerns on embodiment. FIG. 3 is a top view of the transformer module according to the embodiment. The front view of the transformer module which concerns on embodiment. The figure which shows the transformer of the transformer module shown to FIG. 1A, FIG. 1B, and FIG. 1C. FIG. 1B is an exploded perspective view of the electrostatic shield shown in FIGS. 1A, 1B, and 1C. The figure which shows the voltage waveform of the noise of the state which has not covered the transformer with the electrostatic shield. The figure which shows the voltage waveform of the noise of the state which covered the transformer with the electrostatic shield. The figure which shows the transition of the loss of a transformer at the time of changing the width | variety of a slit. The front view of the transformer module provided with the ferrite material. The figure which shows the change of Q value by having formed the slit in the electrostatic shield. The perspective view which shows the other structure of an electrostatic shield. The perspective view which shows the other structure of an electrostatic shield. The perspective view which shows the other structure of an electrostatic shield. The perspective view of a power transmission apparatus and a power receiving apparatus. Schematic of an equivalent circuit when the passive electrodes of the wireless power transmission system are capacitively coupled when the power receiving device is placed on the power transmitting device. The schematic diagram of the equivalent circuit of the wireless power transmission system at the time of making the passive electrode of a power receiving apparatus and a power transmission apparatus directly conduct | electrically_connect.

(Embodiment 1)
Embodiment 1 according to the present invention will be described below. In the present embodiment, a transformer module using the converter transformer according to the present invention will be described. 1 is a side view of a transformer module according to the present embodiment, FIG. 1B is a top view, and FIG. 1C is a front view. FIG. 2 is a diagram showing a transformer of the transformer module shown in FIGS. 1A, 1B, and 1C. FIG. 3 is an exploded perspective view of the electrostatic shield shown in FIGS. 1A, 1B, and 1C.

  The transformer module 10 according to the present embodiment includes a transformer 20 and an electrostatic shield 30 and is mounted on the mounting surface of the mounting board 40. The mounting substrate 40 is, for example, a motherboard of a device including the transformer module 10. A ground electrode pattern 40 </ b> G is provided on the mounting surface of the mounting substrate 40. A transformer 20 and an electrostatic shield 30 described later are provided on the ground electrode pattern 40G.

  The transformer 20 includes a coil bobbin 21. The coil bobbin 21 is formed of, for example, an insulating resin having excellent withstand voltage characteristics. The coil bobbin 21 has an inner cylinder (not shown) that opens straight. In the inner cylinder of the coil bobbin 21, an open magnetic path type core 22 having an I shape with both ends being open ends is inserted so that both ends protrude from the inner cylinder of the coil bobbin 21. Further, the primary winding L1 and the secondary winding L2 are wound around the coil bobbin 21 with the same winding axis. In this embodiment, the primary winding L1 is on the high voltage input side, and the secondary winding L2 is on the low voltage output side.

  The electrostatic shield 30 is a metal member, and is composed of three planes including two parallel side surfaces and an upper surface perpendicular to the two side surfaces. Although the configuration of the electrostatic shield 30 can be changed as appropriate, in the present embodiment, as shown in FIG. 3, the first metal member 31 in which two planes are vertically provided in an L shape, and the plate-like second member. It consists of two members, the metal member 32. The electrostatic shield 30 is provided with the first metal member 31 so that one plane of the first metal member 31 is perpendicular to the mounting surface of the mounting substrate 40, parallel to the one plane, and on the mounting surface of the mounting substrate 40. A second metal member 32 is provided so as to be vertical. As a result, the electrostatic shield 30 is put on the transformer 20 so that each plane is along the axial direction of the core 22 so that the axial direction of the core 22 is opened. The transformer 20 is covered with the electrostatic shield 30 and the ground electrode pattern 40G of the mounting substrate 40.

  The first metal member 31 has a screw hole 31A, for example, and is fixed to the mounting substrate 40 by inserting a screw (not shown) into the screw hole 31A. Further, the second metal member 32 is fixed to another member (not shown) mounted on the mounting substrate 40 or the housing of the transformer module 10 or the like. The first metal member 31, the second metal member 32, and the ground electrode pattern 40G have the same potential.

  An electrostatic shield 30 covering the transformer 20 blocks radiation of the electric field generated from the transformer 20 to the outside. The ground electrode pattern 40G acts as an electrostatic shield material, like the electrostatic shield 30. The electrostatic shield 30 shields the electric field generated from the transformer 20, so that an EMC countermeasure is taken. If EMC countermeasures are not taken, external electronic devices may interfere with noise and not operate normally. Below, the difference of the presence or absence of the EMC countermeasure by the electrostatic shield 30 is demonstrated.

  FIG. 4 is a diagram illustrating a voltage waveform of noise in a state where the transformer 20 is not covered with the electrostatic shield 30. FIG. 5 is a diagram illustrating a voltage waveform of noise in a state where the transformer 20 is covered with the electrostatic shield 30. The thick lines shown in FIGS. 4 and 5 indicate EMC standard values. 4 and 5, the horizontal axis is the frequency axis, and the vertical axis is the noise voltage axis.

  When the transformer 20 is not covered with the electrostatic shield 30, as shown in FIG. 4, the drive frequency of the transformer 20 is about 230 kHz, which exceeds the EMC standard value of about 62 dBμV (dotted line arrow in the figure). On the other hand, when the transformer 20 is covered with the electrostatic shield 30, as shown in FIG. 5, at the same frequency in FIG. 4, it is lower than the EMC standard value of about 62 dBμV (dotted line arrow in the figure). Thus, sufficient EMC countermeasures can be performed by covering the transformer 20 with the electrostatic shield 30.

  Returning to the description of FIG. 3, the first metal member 31 of the electrostatic shield 30 is formed with a plurality of slits 33 extending in the direction orthogonal to the axial direction of the core 22 over two surfaces. The second metal member 32 is formed with a plurality of slits 34 along the normal direction of the mounting surface of the mounting substrate 40, and the second metal member 32 has a comb shape. The slit 33 is formed from the peripheral part of the first metal member 31 on the second metal member 32 side toward the peripheral part on the opposite side. The slit 34 is formed from the peripheral edge of the second metal member 32 on the first metal member 31 side toward the peripheral edge on the opposite side. In other words, the slits 33 and 34 are not closed. An eddy current tends to flow along the peripheral portion of the metal member constituting the three surfaces of the electrostatic shield 30, but a part of the peripheral portion is notched on each of the three surfaces of the electrostatic shield 30 by the slits 33 and 34. Therefore, this eddy current is difficult to flow.

  The electrostatic shield 30 may be configured such that one metal member is curved and covers the transformer 20. Further, the shape of the ground electrode pattern 40G may be a shape provided with a slit that is not closed.

  Below, the relationship between the eddy current generated in each plane of the electrostatic shield 30 and the slits 33 and 34 provided in each plane will be described.

  A current flows through the primary winding L1 and the secondary winding L2 of the transformer 20, and a magnetic flux is formed. When leakage magnetic flux from the formed magnetic flux is incident on the plane of the electrostatic shield 30, the transformer has a transformer. An eddy current is generated that works in the direction of canceling the magnetic flux of 20. If the slits 33 and 34 are not formed in the electrostatic shield 30, the eddy current increases, and as a result, the energy loss due to the generation of the eddy current increases. For this reason, by forming the slits 33 and 34 in each plane of the electrostatic shield 30, an eddy current that tends to flow along the outer periphery of the plane can be suppressed, and as a result, the transformer 20 due to the generation of the eddy current. Energy loss is reduced, and the Q value of the transformer 20 is improved.

  The reduction rate of the loss of the transformer 20 due to the slits 33 and 34 is determined by the width of the slits 33 and 34. FIG. 6 is a diagram showing a change in loss of the transformer 20 when the widths of the slits 33 and 34 are changed. The horizontal axis in FIG. 6 is the L / S value, and the vertical axis is the value obtained by converting the loss into an arbitrary unit. Here, as shown in FIG. 1A, S is the slit width, L is the distance between adjacent slits (the width of the comb teeth between adjacent slits), and the L / S value is the distance L and the width S. Indicates the value of. For example, when the L / S value is (2/2), the slit width is 2 mm and the distance between the slits is 2 mm. Since the length of the magnetic core of the electrostatic shield 30 is constant, the number of comb teeth increases as the L / S value decreases. In FIG. 6, the L / S value and the number of comb teeth are shown together.

  Each point on the graph shown in FIG. 6 indicates the L / S value as (2/2), (3/3), (5/5), (10/10), (17/17), (50 / 50) shows the loss. In FIG. 6, the loss when the L / S value is (50/50) is used as a reference. As shown in the figure, it can be seen that the loss of the transformer 20 decreases as the L / S value decreases, that is, as the number of comb teeth increases. Specifically, when the L / S value is (2/2), the loss is reduced by about 94% compared to the case where the L / S value is (50/50).

  6 shows the case where the width S and the distance L are the same, but from the viewpoint of electrostatic shielding properties, in order to further block the electric field radiated from the transformer 20, the distance L is It is more preferable that the width is longer (thicker) than the width S.

  In order to prevent leakage magnetic flux from entering the electrostatic shield 30, it is more preferable to interpose a ferrite material between the transformer 20 and the electrostatic shield 30. FIG. 7 is a front view of the transformer module 10 including a ferrite material. FIG. 7 is a drawing corresponding to FIG. 1C. In FIG. 7, a plate-like ferrite material 45 is affixed inside the first metal member 31 and the second metal member 32 of the electrostatic shield 30. The transformer 20 is in a state where the upper surface and the side surface are covered with the ferrite material 45. By providing the ferrite material 45, the leakage magnetic flux of the transformer 20 can be prevented from entering the electrostatic shield 30, and eddy current can be more unlikely to be generated in the electrostatic shield 30. Further, since the ferrite material 45 acts as a magnetic shield, the Q value of the transformer 20 is improved.

  FIG. 8 is a diagram illustrating a change in the Q value due to the slits 33 and 34 being formed in the electrostatic shield 30. In FIG. 8, the vertical axis indicates the Q value in each pattern. (1) shown on the horizontal axis is a case where the transformer 20 is not covered with the electrostatic shield 30. (2) is a case where the transformer 20 is covered with an electrostatic shield 30 in which no slit is formed. (3), (4), and (5) are electrostatic shields having slits 33 and 34 having L / S values of (2/2), (1 / 1.5), and (1/2), respectively. In this case, the transformer 20 is covered with 30. (6) is a case where the ferrite material 45 is provided in (3).

  In (1), the highest Q value can be obtained. However, in this case, the EMC countermeasure described above is not taken. On the other hand, in (2), EMC measures are taken, but the lowest Q value is obtained. In the case of (3), (4), (5), (6) in which slits are formed in the electrostatic shield 30, a higher Q value than (2) can be obtained. Moreover, EMC can be kept within an allowable range. Furthermore, in the case of (6) in which the ferrite material 45 is provided, a higher Q value is obtained than in (3), (4), and (5).

  In the present embodiment, as shown in FIG. 3, the electrostatic shield 30 has slits 33 and 34 formed on three surfaces of the electrostatic shield 30. However, the electrostatic shield 30 has a configuration in which slits are formed on one surface or two surfaces. May be. The electrostatic shield 30 covers the transformer 20 together with the ground electrode pattern 40G of the mounting substrate 40. However, the electrostatic shield 30 may have four surfaces, and the four surfaces may cover the transformer 20.

  9, 10 and 11 are perspective views showing other configurations of the electrostatic shield. An electrostatic shield 50 shown in FIG. 9 includes a first metal member 51 and a second metal member 52 having two perpendicular surfaces. A plurality of non-closed slits 53 and 54 are formed on each surface of the first metal member 51 and the second metal member 52, and each surface has a comb shape. A first metal member 51 and a second metal member 52 are provided so as to surround the outer periphery of the transformer 20. The electrostatic shield 50 having this configuration can also suppress eddy currents. As a result, a decrease in the Q value of the transformer 20 can be prevented.

  The electrostatic shield 60 shown in FIG. 10 includes a first metal member 61 having two vertical surfaces, a second metal member 62, a third metal member 63, and a fourth metal member 64. Similarly to the electrostatic shield 50 in FIG. 9, slits that are not closed are formed on each surface, and each surface of the electrostatic shield 60 has a comb shape. And the 1st metal member 61, the 2nd metal member 62, the 3rd metal member 63, and the 4th metal member 64 are provided so that the comb teeth of each surface may mesh with the comb teeth of the adjacent surfaces. Are combined. In FIG. 10, since the slit of one surface is formed by two metal members, the slit width can be easily adjusted.

  Further, the electrostatic shield 70 shown in FIG. 11 is configured by bending so that one meander-shaped metal member forms two surfaces. Even with this configuration, slits are formed on each surface along the outer periphery of the transformer, and eddy currents can hardly flow.

  As described above, any configuration (shape) that makes it difficult to flow eddy current mainly flowing along the peripheral edge of the plane can be changed as appropriate. Further, the number of slits formed in the electrostatic shield 30 or the slit width is appropriately changed depending on the size of the transformer module 10.

(Embodiment 2)
Embodiment 2 according to the present invention will be described below. In the present embodiment, a wireless power transmission system using the transformer module 10 described in the first embodiment will be described.

  The wireless power transmission system according to the present embodiment includes a power transmission device and a power reception device. The power receiving device is, for example, a portable electronic device including a secondary battery. Examples of the portable electronic device include a mobile phone, a PDA (Personal Digital Assistant), a portable music player, a notebook PC (Personal Computer), and a digital camera. The power transmission device is a charging stand on which the power reception device is mounted and charges a secondary battery of the power reception device.

  FIG. 12 is a perspective view of the power transmission device and the power reception device. The power receiving apparatus 200 includes a substantially rectangular parallelepiped casing 201 having a secondary battery (not shown) therein. In the housing 201, one of the two opposing surfaces having the largest area is a front surface and the other is a back surface. The casing 201 is provided with a capacitive input touch panel 202 along the front surface.

  The housing 201 is provided with an active electrode 203 along the back surface. The active electrode 203 has a rectangular shape and is provided such that the longitudinal direction thereof coincides with the longitudinal direction of the back surface of the housing 201. When the power receiving device 200 is placed on the power transmission device 100, the active electrode 203 is opposed to an active electrode 103 (described later) provided on the power transmission device 100 via a gap.

  The housing 201 is provided with a passive electrode 204 along the bottom surface. The bottom surface of the housing 201 has a rectangular shape, and the long side thereof is a surface that coincides with the short sides of the front surface and the back surface. The passive electrode 204 has a rectangular shape and is provided so that the longitudinal direction thereof coincides with the longitudinal direction of the bottom surface of the housing 201. When the power receiving device 200 is disposed in the power transmission device 100, the passive electrode 204 is opposed to or directly connected to a passive electrode 104 (described later) provided in the power transmission device 100 via a gap.

  The power transmission device 100 includes a placement surface 101A that is substantially horizontal to the installation surface, and a backrest surface 101B and a front surface 101C that are substantially perpendicular to the placement surface 101A and face each other in parallel. The placement surface 101A, the backrest surface 101B, and the front surface 101C each have a rectangular shape. The long side of the mounting surface 101A matches the short side of the backrest surface 101B, and the long side of the mounting surface 101A matches the long side of the front surface 101C.

  The power receiving device 200 is mounted on the power transmitting device 100 such that the bottom surface of the power receiving device 200 is on the mounting surface 101A side and the back surface of the power receiving device 200 is on the backrest surface 101B side. The power transmission device 100 includes a passive electrode 104 provided along the placement surface 101A. The passive electrode 104 has a rectangular shape and is provided such that the longitudinal direction thereof coincides with the longitudinal direction of the placement surface 101A. When the power receiving device 200 is mounted on the power transmitting device 100, the passive electrode 104 on the power transmitting device 100 side and the passive electrode 204 on the power receiving device 200 side face each other through a gap or are directly conducted. .

  The power transmission device 100 includes an active electrode 103 provided along the backrest surface 101B. The active electrode 103 has a rectangular shape and is provided such that the longitudinal direction thereof coincides with the height direction of the power transmission device 100. When the power receiving device 200 is mounted on the power transmitting device 100, the active electrode 103 on the power transmitting device 100 side and the active electrode 203 on the power receiving device 200 side face each other.

  In the wireless power transmission system according to the present embodiment, when the power receiving device 200 is mounted on the power transmitting device 100, the passive electrodes 104 and 204 face (or directly conduct), and the active electrodes 103 and 203 face each other. When a voltage is applied between the active electrode 103 and the passive electrode 104 of the power transmission device 100, an electric field is generated between the active electrodes 103 and 203 that are opposed to each other, and power is transmitted via this electric field to the power transmission device 100. To the power receiving apparatus 200. As a result, the power is supplied to the load circuit RL of the power receiving device 200, rectified, and the secondary battery is charged.

  Hereinafter, a circuit configuration of the wireless power transmission system will be described. FIG. 13 is a schematic diagram of an equivalent circuit when the passive electrodes of the wireless power transmission system when the power receiving device 200 is mounted on the power transmitting device 100 are capacitively coupled.

  The power transmission device 100 includes an AC adapter 106 and a voltage generation circuit 107. The AC adapter 106 converts an AC voltage of 100V to 230V into a DC voltage such as 5V, 12V, etc., and outputs it to the voltage generation circuit 107. The voltage generation circuit 107 includes an inverter 108, a step-up transformer TG, and an inductor LG. The voltage generation circuit 107 performs AC conversion and step-up on the voltage input from the AC adapter 106, and applies the voltage between the active electrode 103 and the passive electrode 104. The frequency of the applied voltage is 100 kHz to 10 MHz. The transformer module 10 described in the first embodiment is used for the step-up transformer TG.

  A step-down circuit 205 including a step-down transformer TL and an inductor LL is connected between the active electrode 203 and the passive electrode 204 of the power receiving device 200. A load circuit RL is connected to the secondary side of the step-down transformer TL. The load circuit RL includes a rectifying / smoothing circuit and a secondary battery (not shown). The transformer module 10 described in the first embodiment is used for the step-down transformer TL.

  Thus, by using the transformer module 10 of the first embodiment for the step-up transformer TG and the step-down transformer TL, noise can be reduced and sufficient EMC countermeasures can be taken. In addition, it is possible to prevent noise generated by the power receiving device 200 or the transformer of the power transmitting device 100 from being superimposed on the AC power line.

  FIG. 14 is a schematic diagram of an equivalent circuit of the wireless power transmission system when the passive electrodes 104 and 204 of the power receiving device 200 and the power transmitting device 100 are directly conducted.

  In FIG. 14, a resistor r is connected between the passive electrode 104 of the power transmission device 100 and the passive electrode 204 of the power reception device 200. The resistance r corresponds to the contact resistance configured at the contact portion between the passive electrodes 104 and 204. 13 is the same as FIG. 13 except that a resistor r is connected between the passive electrodes 104 and 204.

  When the capacitance between the active electrodes 103 and 203 is represented by Cm and the frequency of the applied voltage is represented by f, r << 1 / (2πfCm). With this configuration, the potential of the passive electrode 204 of the power receiving device 200 is stabilized, and leakage of unnecessary electromagnetic fields is prevented. Further, in order to boost the power and transmit power, the current flowing through the passive electrodes 104 and 204 may be on the order of several mA. In a conventional contact-type charging device, a charging current on the order of several A flows as it is, so that loss due to contact resistance is large. In the present invention, it is not necessary to keep contact resistance low, and various contact means can be applied.

  It should be noted that the specific configuration of the transformer module 10 and the like described above can be changed in design as appropriate, and the actions and effects described in the above-described embodiments are merely a list of the most preferable actions and effects resulting from the present invention. The operations and effects of the present invention are not limited to those described in the above embodiment.

  In the above-described example, the active electrodes or the passive electrodes of the power transmitting device and the power receiving device are opposed to each other via a gap. However, the effect of the present application is not limited to this, and the facing electrodes It is only necessary that the two are capacitively coupled. For example, a dielectric material such as plastic that forms the housing of the device, an insulating liquid, a gas, or the like, that is, a material that insulates the electrodes from each other, or a combination of a plurality of materials that include them is arranged between the electrodes, so that there is no gap between the electrodes. What is necessary is just to become the structure which is not electrically connected in direct current.

10-transformer module 20-transformer 21-coil bobbin 22-core 30-electrostatic shield 33, 34-slit (notched portion)
40-Mounting board (box)
L1-primary winding L2-secondary winding

Claims (11)

A magnetic core that forms an open magnetic path;
A winding wound around the magnetic core;
An electrostatic shield covering the magnetic core around which the winding is wound;
With
In the electrostatic shield, a plurality of slits extending in the direction perpendicular to the axial direction of the magnetic core are formed along the axial direction ,
The width of the slit in the axial direction is shorter than the distance between adjacent slits,
Converter transformer. A magnetic core that forms an open magnetic path;
A winding wound around the magnetic core;
An electrostatic shield covering the magnetic core around which the winding is wound;
With
The electrostatic shield is formed with a slit extending in a direction orthogonal to the axial direction of the magnetic core ,
The electrostatic shield has two comb-shaped members,
The two comb-shaped members are opposed to each other, and the respective comb teeth are inserted into each other so as to form the slit therebetween,
Converter transformer. The winding has a primary winding and a secondary winding wound adjacently;
One of the primary winding and the secondary winding is on the higher voltage side than the other,
The converter transformer according to claim 1 or 2 . The electrostatic shield has at least three surfaces along the axial direction of the magnetic core,
A slit is formed on each of the three surfaces,
The converter transformer in any one of Claim 1 to 3 . 5. The converter transformer according to claim 4 , wherein the slit is formed in each of the three surfaces from the peripheral edge toward the inside.   The converter transformer according to claim 5, further comprising a surrounding portion having a surface that covers the magnetic core together with the three surfaces of the electrostatic shield.   The converter transformer according to claim 1, further comprising a ferrite member provided between the electrostatic shield and the winding. A magnetic core that forms an open magnetic path, a transformer having a primary winding and a secondary winding wound around the magnetic core, and
An electrostatic shield that covers the transformer and has a plurality of slits extending in the direction perpendicular to the axial direction of the magnetic core ;
A substrate on which the transformer and the electrostatic shield are mounted;
Bei to give a,
The width of the slit in the axial direction is shorter than the distance between adjacent slits,
Transformer module. A magnetic core that forms an open magnetic path, a transformer having a primary winding and a secondary winding wound around the magnetic core, and
An electrostatic shield that covers the transformer and has a slit formed in a direction perpendicular to the axial direction of the magnetic core ;
A substrate on which the transformer and the electrostatic shield are mounted;
Bei to give a,
The electrostatic shield has two comb-shaped members,
The two comb-shaped members are opposed to each other, and the respective comb teeth are inserted into each other so as to form the slit therebetween,
Transformer module. A power transmission device having a power generation side active electrode, a power transmission side passive electrode, and a voltage generation circuit for applying a voltage between the power transmission side active electrode and the power transmission side passive electrode;
A power receiving side active electrode facing the power transmitting side active electrode, a power receiving side passive electrode facing or contacting the power transmitting side passive electrode, the power receiving side active electrode, and the power receiving side when mounted on the power transmitting device A step-down circuit for stepping down a voltage generated between the passive electrodes, and a power receiving device having a load circuit for inputting an output voltage of the step-down circuit as a power supply voltage;
In the wireless power transmission system for transmitting power from the power transmitting device side to the power receiving device side by capacitively coupling the power transmitting side active electrode and the power receiving side active electrode through an insulator,
The voltage generation circuit or the step-down circuit is
A magnetic core that forms an open magnetic path, a transformer having a primary winding and a secondary winding wound around the magnetic core, and
An electrostatic shield that covers the transformer and has a plurality of slits extending in the direction perpendicular to the axial direction of the magnetic core ;
Have
The width of the slit in the axial direction is shorter than the distance between adjacent slits,
Wireless power transmission system. A power transmission device having a power generation side active electrode, a power transmission side passive electrode, and a voltage generation circuit for applying a voltage between the power transmission side active electrode and the power transmission side passive electrode;
A power receiving side active electrode facing the power transmitting side active electrode, a power receiving side passive electrode facing or contacting the power transmitting side passive electrode, the power receiving side active electrode, and the power receiving side when mounted on the power transmitting device A step-down circuit for stepping down a voltage generated between the passive electrodes, and a power receiving device having a load circuit for inputting an output voltage of the step-down circuit as a power supply voltage;
In the wireless power transmission system for transmitting power from the power transmitting device side to the power receiving device side by capacitively coupling the power transmitting side active electrode and the power receiving side active electrode through an insulator,
The voltage generation circuit or the step-down circuit is
A magnetic core that forms an open magnetic path, a transformer having a primary winding and a secondary winding wound around the magnetic core, and
An electrostatic shield that covers the transformer and has a slit formed in a direction perpendicular to the axial direction of the magnetic core ;
Have
The electrostatic shield has two comb-shaped members,
The two comb-shaped members are opposed to each other, and the respective comb teeth are inserted into each other so as to form the slit therebetween,
Wireless power transmission system.

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