JP7368303B2 - power supply - Google Patents

Description

The present invention relates to a power supply device.

Conventionally, as isolated power supplies with several kilowatt output that perform DC/DC (direct current/direct current) voltage conversion, phase shift full bridge DC/DC converters, LLC DC/DC converters, and DAB (dual active converters) have been used. Bridge type bidirectional DC/DC converters are known. These power supplies use switching elements and high frequency isolation transformers.

In recent years, high-frequency power switching elements using SiC (silicon carbide), GaN (gallium nitride), or the like have been put into practical use as switching elements. Conventional silicon-based IGBTs (insulated gate bipolar transistors) and MOSFETs (metal oxide semiconductor field effect transistors) had a driving frequency of several tens of kilohertz, but power switching elements that support high frequencies Since switching loss can be reduced, operation at frequencies exceeding 100 kilohertz is also possible.

On the other hand, a high-frequency isolation transformer is a transformer that transmits power through electromagnetic induction, and uses core materials compatible with high frequencies such as manganese-zinc ferrite, manganese-nickel ferrite, amorphous material, and nanocrystalline material. However, in general, operation at around 100 kilohertz is the practical limit, including material properties and cooling.

In other words, in conventional power supply devices, high-frequency isolation transformers cannot keep up with the higher speeds (higher frequencies) of switching elements.In other words, it is difficult to take advantage of the high-frequency, low-loss characteristics of high-frequency compatible power switching elements such as SiC and GaN. The problem is that they are not.

In addition, in conventional power supply devices, the size, cost, and weight of high-frequency isolation transformers increase when used for several kilowatts, efficiency decreases due to iron loss when high-frequency isolation transformers are operated at high frequencies, and heat sinks for heat dissipation are required. Another problem is that the heat dissipation material becomes larger.

Patent Document 1 describes a power supply device including an air-core transformer (air-core transformer) without a core material. Since this power supply device has a series resonant circuit on the primary side and a full-wave rectifier circuit (non-resonant circuit) on the secondary side, the resonance Q value is small. Furthermore, since the air core transformer has a small coupling coefficient, the power supply device described in Patent Document 1 has low transmission efficiency. As a result, the power supply device described in Patent Document 1 has an output limit of about several watts, and cannot output large power of several kilowatts.

Special Publication No. 2010-522535

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a power supply device that is compact and capable of outputting large amounts of power.

In order to solve the above problems, a power supply device according to the present invention includes:
a coil unit including a first coil and a second coil;
a primary side circuit including a first capacitor and a first switch circuit, the first capacitor forming a first resonant circuit together with the first coil;
a secondary side circuit including a second capacitor and a second switch circuit, the second capacitor forming a second resonant circuit together with the second coil;
comprising a control unit;
The first coil and the second coil are fixed so as to face each other at a certain distance,
The control unit is characterized in that it controls the first switch circuit and the second switch circuit so that the coil unit performs power transmission by magnetic field resonance.

According to this configuration, a coil unit including a first coil and a second coil fixed so as to face each other at a certain distance is provided instead of the high frequency isolation transformer, so that miniaturization is possible. Furthermore, according to this configuration, since the coil unit performs power transmission by magnetic field resonance, it becomes possible to output large power of, for example, several kilowatts.

In the above power supply device,
The first switch circuit is configured with a single first switching element in which first diodes are connected in antiparallel,
Preferably, the second switch circuit is configured with a single second switching element in which second diodes are connected in antiparallel.

In the above power supply device,
The first resonant circuit and the second resonant circuit may both be parallel resonant circuits.

The above power supply device is
Further equipped with heat dissipation material and metal exterior,
The coil unit, the primary circuit, and the secondary circuit may be arranged on the heat dissipation material and accommodated in the metal sheath.

In the above power supply device,
The first coil and the second coil may both be planar coils or solenoid coils in which a coil wire is wound in two stages and no winding is formed on the inner periphery.

According to the present invention, it is possible to provide a power supply device that is compact and capable of outputting high power.

1 is a circuit diagram of a power supply device according to the present invention. FIG. 2 is a perspective view of a coil unit according to the present invention. It is a figure showing a bobbin and a coil guide of a coil unit concerning the present invention. FIG. 3 is a cross-sectional view of a first coil and a second coil according to the present invention. It is a sectional view of the 1st coil concerning a modification. FIG. 7 is a perspective view of a coil unit according to a modification.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of a power supply device according to the present invention will be described with reference to the accompanying drawings.

[Power supply configuration]
FIG. 1 shows a power supply device 1 according to an embodiment of the present invention. The power supply device 1 is an insulated DC/DC power supply device, and includes a coil unit 10, a primary circuit 20, a secondary circuit 30, a control section 40, and a metal exterior 50. The power supply device 1 transmits power from the primary circuit 20 to the secondary circuit 30 (forward power transmission), and from the secondary circuit 30 to the primary circuit 20 (reverse power transmission). I do.

The power supply device 1 includes first input/output terminals T ₁₁ , T ₁₂ and second input/output terminals T ₂₁ , T ₂₂ . The first input/output terminals T ₁₁ and T ₁₂ are connected to, for example, an AC/DC conversion circuit or a PFC (power factor correction) circuit. The second input/output terminals T ₂₁ and T ₂₂ are connected to, for example, a DC load or a battery. A first filter circuit (for example, an LC filter circuit) is provided between the first input/output terminals T ₁₁ , T ₁₂ and the primary side circuit 20, and the second input/output terminals T ₂₁ , T ₂₂ and the secondary side circuit 30, a second filter circuit (for example, an LC filter circuit) may be provided. Further, a buck-boost converter may be provided outside the second input/output terminals T ₂₁ and T ₂₂ to adjust the voltage to a desired level.

The coil unit 10 includes a first coil L ₁ and a second coil L ₂ fixed so as to face each other at a certain distance D. The first coil L ₁ and the second coil L ₂ are both planar coils in which coil wire is wound in two stages. Detailed configurations of the first coil L ₁ and the second coil L ₂ will be described later.

The primary side circuit 20 includes a first capacitor C ₁ and a first switch means SW ₁ corresponding to the "first switch circuit" of the present invention. The first capacitor C ₁ is connected in parallel to the first coil L ₁ and constitutes a parallel resonant circuit (corresponding to the “first resonant circuit” of the present invention) together with the first coil L ₁ . The first switch means _SW1 serves as a driving element for causing the first resonant circuit to operate in resonance.

The secondary circuit 30 includes a second capacitor _C2 and a second switch means _SW2 , which corresponds to the "second switch circuit" of the present invention. The second capacitor _C2 is connected in parallel to the second coil _L2 , and forms a parallel resonant circuit (corresponding to the "second resonant circuit" of the present invention) together with the second coil _L2 . The second switch means _SW2 serves as a driving element for causing the second resonant circuit to operate in resonance.

The first switching means SW ₁ includes a first switching element Q ₁ connected in series to a first capacitor C ₁ and a first coil L ₁ , and a first diode D ₁ connected in antiparallel to the first switching element Q ₁ . including. The first diode _D1 is a built-in (parasitic) diode of the first switching element _Q1 or a diode independent of the first switching element _Q1 .

The second switching means _SW2 includes a second switching element _Q2 connected in series to the second capacitor _C2 and the second coil _L2 , and a second diode _D2 connected in antiparallel to the second switching element _Q2 . including. The second diode _D2 is a built-in (parasitic) diode of the second switching element _Q2 or a diode independent of the second switching element _Q2 .

The first switching element Q ₁ and the second switching element Q ₂ are preferably high-frequency compatible power switching elements using SiC (silicon carbide), GaN (gallium nitride), etc., but power switching elements using silicon may also be used. But that's fine. As the power switching element, an IGBT (insulated gate transistor), a MOSFET (metal oxide semiconductor field effect transistor), or a bipolar transistor is used.

The first coil L ₁ and the primary circuit 20 are single-ended converters that operate with a single drive element (first switch means SW ₁ ). Similarly, the second coil L ₂ and the secondary circuit 30 are single-ended converters that operate with a single drive element (second switch means SW ₂ ). According to such a configuration, it is possible to reduce costs, downsize the mounting space, and simplify control. Note that if the allowable current capacity of the first switch means SW ₁ and the second switch means SW ₂ is less than the required current, a plurality of the first switch means SW ₁ and the second switch means SW ₂ may be connected in parallel. shall also be included.

The control unit 40 includes a first resonant voltage detection circuit 41 , a second resonant voltage detection circuit 42 , a first synchronous circuit 43 , a second synchronous circuit 44 , and a control circuit 45 . The first synchronous circuit 43 includes a drive circuit (gate drive circuit) for the first switch means _SW1 , and the second synchronous circuit 44 includes a drive circuit (gate drive circuit) for the _second switch means SW2.

The first resonant voltage detection circuit 41 measures the voltage V _R1 across the first capacitor _C1 and detects the zero-crossing point of the resonant voltage of the first resonant circuit. The first resonant voltage detection circuit 41 that has detected the zero-cross point outputs a zero-cross signal to the first synchronization circuit 43.

The second resonant voltage detection circuit 42 measures the voltage V _R2 across the second capacitor _C2 and detects the zero-crossing point of the resonant voltage of the second resonant circuit. The second resonant voltage detection circuit 42 that has detected the zero-cross point outputs a zero-cross signal to the second synchronization circuit 44.

The first synchronous circuit 43 performs zero-voltage switching operation of the first switching element _Q1 in synchronization with the resonant voltage of the first resonant circuit (in this embodiment, in synchronization with the zero-cross signal) during forward power transmission. The first switching element Q1 is turned on, and after a preset on time has elapsed, the first switching element _Q1 is turned off. Furthermore, during reverse power transmission, the first synchronous circuit 43 turns off the first switching element Q ₁ under the control of the control circuit 45 so that the first diode D ₁ performs a rectification operation.

The second synchronous circuit 44 turns off the second switching element Q ₂ under the control of the control circuit 45 so that the second diode D ₂ performs a rectification operation during forward power transmission. Further, during reverse power transmission, the second synchronous circuit 44 causes the second switching element _Q2 to perform zero voltage switching operation in synchronization with the resonant voltage of the second resonant circuit (in this embodiment, in synchronization with the zero cross signal). The second switching element Q2 is turned on, and after a preset on time has elapsed, the second switching element _Q2 is turned off.

The control circuit 45 controls the _voltage difference ( _first voltage A first voltage difference control is performed to control the voltage difference).

The control circuit 45 starts the first voltage difference control in response to an external control command signal _S1 . The control circuit 45 that has started the first voltage difference control detects the voltage value of the first input voltage _E1 based on the first detection signal _S2 of the first detection means _X1 (for example, a current transformer) at a predetermined period. And/or obtain the current value of the first input current flowing between the first input/output terminals T ₁₁ , T ₁₂ and the primary circuit 20 . The control circuit 45 also acquires information regarding the output power output from the secondary circuit 30 at a predetermined period. The information regarding the output power includes the power value of the output power, the voltage value of the first output voltage _E2 , and the power value of the output power, or the voltage value of the first output voltage _E2 and the second input/output terminals _T21 , _T22 . This is the current value of the first output current flowing between the secondary side circuit 30 and the secondary side circuit 30.

The control circuit 45 controls the AC/DC connected to the first input/output terminals T ₁₁ and T ₁₂ so that the power value of the output power becomes a predetermined target power value while acquiring the necessary information as described above. A voltage command signal _S3 is output to the conversion circuit or the PFC circuit to control the first input voltage _E1 . That is, the control circuit 45 controls the first voltage difference by controlling the first input voltage _E1 .

During forward power transmission, when the control circuit 45 performs first voltage difference control and the first synchronous circuit 43 performs on/off control of the first switching element _Q1 , the first coil _L1 and the first capacitor _C1 Current flows. As a result, a current flows through the second coil L ₂ and the second capacitor C ₂ that are separated by a certain distance due to magnetic field resonance (synonymous with magnetic field resonance, magnetic resonance, and magnetic resonance). As a result, contactless (transformerless) power transmission is performed from the primary circuit 20 to the secondary circuit 30.

In addition _, the control circuit 45 controls the voltage difference ( _second A second voltage difference control is performed to control the voltage difference).

The control circuit 45 starts the second voltage difference control in response to an external control command signal _S1 . The control circuit 45 that has started the second voltage difference control detects the voltage value of the second input voltage E ₂ based on the second detection signal S ₄ of the second detection means X ₂ (for example, a current transformer) at a predetermined period. And/or obtain the current value of the second input current flowing between the second input/output terminals T ₂₁ and T ₂₂ and the secondary circuit 30. The control circuit 45 also acquires information regarding the output power output from the primary circuit 20 at a predetermined period. The information regarding the output power includes the power value of the output power, the voltage value of the second output voltage _E1 , and the power value of the output power, or the voltage value of the second output voltage _E1 and the first input/output terminals _T11 , _T12. This is the current value of the second output current flowing between the primary side circuit 20 and the primary side circuit 20.

While acquiring the necessary information as described above, the control circuit 45 outputs a voltage command signal _S3 to the DC load or battery control device so that the power value of the output power becomes a predetermined target power value. A second input voltage _E2 is controlled. That is, the control circuit 45 controls the second voltage difference by controlling the second input voltage _E2 . The control circuit 45 controls the second output voltage E 1 by outputting a voltage command signal S ₃ to the AC/DC conversion circuit or PFC circuit connected to the first input/output terminals T ₁₁ and T ₁₂ (for example, the second output voltage E _{1 )} . The second voltage difference may be controlled by lowering or increasing the second output voltage _E1 relative to the second input voltage _E2 .

During reverse power transmission, when the control circuit 45 performs second voltage difference control and the second synchronous circuit 44 performs on/off control of the second switching element _Q2 , the second coil _L2 and second capacitor _C2 Current flows. As a result, a current flows through the first coil L ₁ and the first capacitor C ₁ that are separated by a certain distance due to magnetic field resonance. As a result, contactless power transmission is performed from the secondary circuit 30 to the primary circuit 20.

The metal exterior 50 includes a heat dissipating material (for example, a heat sink) inside or outside thereof. The coil unit 10, the primary side circuit 20, the secondary side circuit 30, and the control unit 40 are housed in the metal exterior 50 in a state where they are placed on a heat dissipation material (for example, a heat sink) as necessary. In particular, by accommodating the coil unit 10 within the metal exterior 50, the external space is not used as a transmission path for power transmission, so it does not fall under the regulations of the Radio Law, and it is also less susceptible to leakage magnetic fields and radiated noise than normal power supplies. It is also possible to limit the amount in the same way.

The power supply device 1 according to the present embodiment includes a coil unit 10 including a first coil L ₁ and a second coil L ₂ fixed so as to face each other at a certain distance D, instead of a high frequency isolation transformer. That is, since the power supply device 1 does not use a high-frequency isolation transformer that is large in volume and weight, it can be made smaller. Furthermore, in the power supply device 1 according to the present embodiment, the primary side circuit 20 and the secondary side circuit 30 are single-ended converters that operate with a single drive element, so they are smaller and lower in cost than bridge-type converters. Cost reduction becomes possible.

In the power supply device 1 according to the present embodiment, since the coil unit 10 performs power transmission by magnetic field resonance, it is possible to output large power of, for example, several kilowatts. Furthermore, in the power supply device 1, a reduction in the coupling coefficient due to the fact that the coil unit 10 does not have a core can be compensated for by the Q value of the resonance, which becomes larger when the coil unit 10 performs magnetic field resonance. As a result, the power supply device 1 can obtain high transmission efficiency equivalent to or higher than that of a power supply device equipped with a high frequency isolation transformer.

[Coil unit configuration]
The coil unit 10 includes a first coil L ₁ and a second coil L ₂ that are fixed at a constant distance D such that their coil surfaces are parallel to each other and their central axes perpendicular to the coil surfaces face each other on the same line. The fixed distance D is a shorter distance than in general non-contact power transmission, and the coupling coefficient between the first coil _L1 and the second coil _L2 is set to a value within the range of about 0.3 to 0.7. is set to For example, if the outer diameter of the first coil L ₁ and the second coil L ₂ is 120 [mm] and the alpha winding is 8 turns (8 turns), the constant distance D is within the range of about 8 to 30 [mm]. set to the value. In this case, the coil unit 10 has a volume of about 1/2 and a weight of less than 1/2 compared to a conventional high frequency isolation transformer for several kilowatts.

In addition, in the case of a wireless charging system in which one coil is provided in the electric vehicle (power receiving device) and the other coil is provided in the power supply device, the distance between one and the other coil is 30 [mm] or more (for example, 45 [mm] or more). mm]), the coupling coefficient between the coils is in the range of about 0.1 to 0.3, and the outer diameter of the coil is large, about several hundred [mm]. Furthermore, wireless charging systems have a problem in that when the height of the electric vehicle changes, the distance between the coils changes, and the relationship between the center positions of the coils also changes each time power is supplied. That is, when the distance between the coils increases or the coils deviate from the center position, the coupling coefficient between the coils decreases, and the transmission efficiency decreases.

On the other hand, as described above, the coil unit 10 is used while being fixed with the center positions of the coils aligned at a certain distance D, so the coil outer diameter is approximately 120 [mm], making it a fraction of the size. The coupling coefficient is about 0.3 to 0.7, which is 2 to 3 times higher, which improves efficiency, and since the position is fixed, it can be used at the best efficiency, and the coupling coefficient changes. This has the advantage of eliminating the need for complex control.

FIG. 2 shows a perspective view of the coil unit 10. The coil unit 10 includes a first coil _L1 , a second coil _L2 , and a fixing member (not shown) that fixes these at a constant distance D.

The first coil L ₁ includes a shield plate 11 , a ferrite plate 12 , a coil sheet 13 , a transmission coil 14 , and a bobbin 15 . The second coil _L2 has the same configuration as the first coil _L1 . The first coil L ₁ and the second coil L ₂ are fixed at a certain distance D so that the transmission coils 14 face each other. Note that the shield plate 11, coil sheet 13, and bobbin 15 can be omitted.

The shield plate 11 is made of, for example, an aluminum plate. The shield plate 11 is provided to reduce the magnetic field leaking to the outside. A heat dissipation member (for example, a heat sink) may be connected to the shield plate 11. By connecting the heat radiating member, copper loss heat generated from the transmission coil 14 due to heat conduction can be efficiently diffused to the outside via the heat radiating member.

The ferrite plate 12 is made larger than the transmission coil 14, is provided to form a magnetic path to prevent magnetic flux from going outside, and is provided to improve the coupling coefficient, and is disposed inside the shield plate 11. A heat dissipation sheet may be attached to the ferrite plate 12 to increase the thermal conductivity from the ferrite plate 12. The ferrite plate 12 may be a single plate, a hollow plate, a partially radially arranged rod-shaped plate, or a spread of ferrite plate blocks. Instead of the ferrite plate 12, a member made of another magnetic material such as an amorphous material or a nanocrystalline material may be used. By making the ferrite plate 12 larger than the transmission coil 14 (for example, by making the length of the diagonal line of the ferrite plate 12 larger than the coil outer diameter of the transmission coil 14), the transmission coil 14 is formed by providing the shield plate 11. This reduces the effects of lower inductance and coupling coefficient.

Coil sheet 13 is placed inside ferrite plate 12 . A non-magnetic and insulating member is used for the coil sheet 13. By providing the coil sheet 13 with a material with high heat dissipation properties (for example, a heat dissipation sheet), or by making the coil sheet 13 with a material with high heat dissipation properties, the heat generated from the transmission coil 14 may be efficiently diffused to the outside. .

The transmission coil 14 is composed of a coil wire wound in a spiral shape, and is arranged inside the coil sheet 13. The coil wire of the transmission coil 14 may be a litz wire or a flat wire in order to reduce the skin effect at high frequencies. Although the shape of the transmission coil 14 is circular, it may be of any shape as long as it provides the required inductance and a coupling coefficient within the range of about 0.3 to 0.7. I can do it. For example, it may be rectangular with arcuate corners, or it may be elliptical or track-shaped with straight portions along its long axis.

However, in planar bulk (sheet) coils, it is known that heat generation due to Joule loss in the inner circumference of the coil becomes noticeable due to the influence of the magnetic field (proximity effect) caused by the induced current flowing in the outer circumference of the coil. . This phenomenon is not normally a problem with Litz wires, but it becomes a problem especially in the case of small planar coils and magnetic field resonant circuits in which high-frequency, large resonant currents flow through the coils. In other words, this is not a problem in the case of a large coil for electric vehicles made of Litz wire, but in the case of the coil unit 10 of this embodiment, which is a small planar coil, the influence of the magnetic field generated by the induced current flowing around the outer circumference of the coil is not a problem. (proximity effect), heat generation due to Joule loss in the inner circumference of the coil becomes noticeable. For this reason, in the coil unit 10, the inner circumference (inner diameter) of the coil is provided in the transmission coil 14 using the bobbin 15, and no coil (winding) is formed in the inner circumference of the coil. In this case, it is preferable that the transmission coil 14 has an inner diameter of 60% or more of the outer diameter of the coil, for example, an inner diameter of about 2/3 of the outer diameter of the coil.

In the case of coils for electric vehicles, the ground side is large and the vehicle side is small, and their characteristics (wire material, inductance, resistance value, etc.) are different, but the transmission of the first coil L ₁ and the second coil L ₂ of this embodiment Since the coils 14 are fixed facing each other with their center positions aligned at a certain distance D, they may be of the same size and have the same characteristics, resulting in excellent productivity.

The bobbin 15 is provided to make it easier to wind the transmission coil 14, and is arranged at the center of the transmission coil 14. The bobbin 15 is provided with a non-magnetic and insulating coil guide 16 as shown in FIG. The coil guide 16 has grooves on the upper and lower surfaces that facilitate winding of the coil wire of the transmission coil 14, and a notch 16a through which the coil wire passes between the upper and lower surfaces.

FIG. 4 shows a cross-sectional view of the first coil L ₁ and the second coil L ₂ on a plane passing through the center line. As shown in FIG. 4, the transmission coil 14 is wound from No. 1 on the lower side of the coil guide 16 (the side closer to the coil sheet 13) along the bobbin 15, and then wound on the upper side of the coil guide 16 (the side closer to the coil sheet 13). After winding No. 2 and No. 3 on the far side of the coil guide 16, No. 4 and No. 5 on the lower side of the coil guide 16 are wound in that order. The transmission coil 14 moves between the upper side and the lower side via the notch 16a.

In this winding method, the transmission coils 14 with consecutive winding orders are arranged adjacent to each other, and the transmission coils 14 with different winding orders are arranged so as not to be adjacent, so that the coil wires of the transmission coils 14 with different winding orders are arranged. This makes dielectric breakdown less likely to occur due to voltage differences. With this winding method, the coil wire of the transmission coil 14 can be constructed with a thin insulation coating, so that the transmission coil 14 can be made smaller, lighter, and lower in cost.

Since the transmission coil 14 is a planar coil having a two-layer (two-tiered) structure with the coil guide 16 in between, it is smaller than a planar coil having a single-layer structure. Nevertheless, the transmission coil 14 is a small coil that can obtain the required inductance, has a high coupling coefficient, and has good transmission efficiency. In addition, the transmission coil 14 is a small coil that has a small outer diameter and can prevent significant heat generation at the inner circumference of the coil even if it is in a magnetic field resonance circuit where a large resonance current flows at high frequency. Become.

Conventional high-frequency isolation transformers for several kilowatts have poor heat dissipation properties because they have a sealed three-dimensional structure that makes it difficult for heat generated by iron loss and copper loss in the coil to be transmitted to the outside. On the other hand, since the coil unit 10 has a coreless structure without a core, there is no heat generation due to iron loss. Furthermore, in the coil unit 10, since the transmission coil 14 is a planar coil, heat generated by copper loss of the coil is easily transmitted to the outside. Further, since the first coil L ₁ and the second coil L ₂ are separated by a certain distance D, the heat generated from the transmission coil 14 can be diffused to the outside by natural convection or forced air cooling.

Since the coil unit 10 has a coreless structure as described above, there is no loss caused by increasing the frequency of the core material, which is a problem with high frequency isolation transformers. Therefore, when power switching elements compatible with high frequencies such as SiC and GaN are used as the first switching element Q ₁ and the second switching element Q ₂ , the power supply device 1 including the coil unit 10 can generate high-frequency waves by the power switching elements.・You can take advantage of characteristics such as low loss. As a result, the power supply device 1 according to this embodiment can operate at a drive frequency exceeding 100 [kHz].

The coil unit 10 has a volume of about 1/2 and a weight of less than 1/2 compared to a high frequency isolation transformer for several kilowatts. Therefore, the power supply device 1 according to the present embodiment can achieve reductions in size, weight, and cost.

By downsizing the coil unit 10, it is possible to reduce loss (improve efficiency) by lowering the resistance value of the transmission coil 14, and to reduce costs by reducing the amount of expensive coil wire materials such as litz wire used in the transmission coil 14.

In the coil unit 10, since the distance between the first coil _L1 and the second coil _L2 is fixed at a constant distance D, the efficiency does not decrease due to a change in the coupling coefficient, so that the special efficiency in the control circuit 45 is reduced. No countermeasures against the decline are required. Therefore, adjustment of control parameters during control of the control circuit 45 (for example, during first voltage difference control and second voltage difference control) becomes easy, and operation under control conditions with the highest transmission efficiency is possible. .

In this embodiment, the first coil _L1 and the second coil _L2 , which are separated by a certain distance D, are fixed vertically, but the first coil _L1 and the second coil, which are separated by a certain distance D, are fixed vertically. _L2 may be fixed in a horizontal position.

Although the embodiments of the power supply device according to the present invention have been described above, the present invention is not limited to the above embodiments.

[Modified example]
The power supply device according to the present invention includes a coil unit including a first coil and a second coil, a first capacitor and a first switch circuit, and a primary side in which the first capacitor constitutes a first resonant circuit together with the first coil. a secondary circuit including a second capacitor and a second switch circuit, in which the second capacitor constitutes a second resonant circuit together with a second coil, and a control unit, the first coil and the second coil comprising: They are fixed so as to face each other at a certain distance, and the configuration of the control section can be changed as appropriate as long as the control section controls the first switch circuit and the second switch circuit so that the coil unit performs power transmission by magnetic field resonance.

For example, the control unit 40 of the embodiment described above may perform control based on the voltage difference between input and output voltages including first voltage difference control and second voltage difference control, or may perform control based on the voltage difference between the input and output voltages including first voltage difference control and _second voltage difference control. Phase shift control may be performed such that the switching of the element Q ₁ ) and the switching of the second switching means SW ₂ (or the second switching element Q ₂ ) have a predetermined phase difference.

Although the power supply device 1 of the above embodiment is a power supply device that performs bidirectional power transmission, the power supply device according to the present invention may be a power supply device that performs only unidirectional power transmission. Further, the power supply device 1 has a circuit configuration with parallel resonance/parallel resonance on the primary side/secondary side, but the power supply device according to the present invention has a circuit configuration with series resonance/series resonance on the primary side/secondary side. Alternatively, at least one of the primary side and the secondary side may have a circuit configuration combining series resonance and parallel resonance.

The first switch circuit of the present invention may have a bridge type or full bridge type circuit configuration including a plurality of switch means. Similarly, the second switch circuit of the present invention may have a bridge type or full bridge type circuit configuration including a plurality of switch means. However, from the viewpoint of cost reduction, miniaturization of mounting space, and simplification of control, a single-ended converter configuration as in the above embodiment is preferable.

5A to 5E show cross-sectional views of a coil unit 10 according to a modified example. The second coil _L2 has the same configuration as the first coil _L1 , so it will be omitted.

The winding method shown in FIG. 5(A) starts from No. 1 on the bottom of the coil guide 16 along the bobbin 15, winds No. 2 on the top of the coil guide 16, then winds No. 3 on the bottom, and then No. 4 on the top of the coil guide 16. This is a winding method in which the wires are wound alternately in order of number. This winding method is similar to the winding method of the above embodiment, by arranging transmission coils 14 with consecutive winding orders adjacent to each other, and arranging transmission coils 14 with different winding orders so as not to arrange them adjacently. This makes it difficult for dielectric breakdown to occur due to a voltage difference between the coil wires of the transmission coils 14 that are separated from each other.

The winding method shown in FIG. 5(B) is to wind the lower Nos. 1 and 2 along the bobbin 15 without the coil guide 16, wind the upper Nos. 3 and 4, and then wind the lower No. 5, This is a winding method in which the wires are rolled in the order of number 6. In this winding method, compared to the winding method of the above-described embodiment, the transmission coils 14 having successive winding orders are slightly apart, but since the upper side is wound after the lower side is wound, the winding becomes easier.

The winding method shown in FIG. 5(C) is to wind the lower No. 1 along the bobbin 15 without the coil guide 16, wind the No. 2 on top of it, and alternately wind the No. 3 on the lower side and the No. 4 above it. This is a winding method in which it is rolled around. This winding method is simple, and the upper transmission coil 14 is wound on the lower transmission coil 14, making it easier to wind.

The winding method shown in FIG. 5(D) is a two-layer alpha winding, in which the lower first layer is wound from the outer periphery toward the center (bobbin 15), and the upper second layer is wound from the center (bobbin 15) to the outer periphery. This is a winding method in which it is rolled towards the end. In the case of this winding method, the transmission coil 14 can be efficiently produced using an alpha winding machine. In the case of winding using an automatic alpha winding machine, a Litz wire with a square cross section may be used, and the lower first layer and the upper second layer may be wound from the inside to the outside without the bobbin 15.

The winding method shown in FIG. 5E is a two-layer alpha winding method in which a non-magnetic insulating sheet 17 is further sandwiched between the first layer and the second layer. The configuration shown in Figure 5 (D) (configuration with only alpha-wound two-layer coils) has no problem with pressure resistance because the number of turns is continuous between the coil wires in the same layer, but between different layers (between the first layer and the second layer) ), the number of turns is far apart, which may cause problems with withstand voltage such as dielectric breakdown. On the other hand, in the configuration shown in FIG. 5(E), the insulation sheet 17 is sandwiched to strengthen the dielectric strength, so the transmission coil 14 can be efficiently manufactured using the alpha winding machine. In addition, it is possible to make dielectric breakdown less likely to occur.

The transmission coil of the present invention is not limited to a two-layer structure (two-layer structure), but may be a planar coil having a structure of one layer or three or more layers. If the coil inductance required for the coil unit 10 falls within the desired coil size, a single layer structure may be used, but if it does not, it is desirable to adopt a two or more layer structure to fit within the desired size. By making the coil unit 10 such a small coil, the power supply device according to the present invention becomes a small and highly efficient power supply.

Further, the transmission coil of the present invention is not limited to a planar coil, but may be a solenoid coil as long as it has a desired inductance and a small coil size. In the case of solenoid coils, both single- and multi-layer windings, they can be easily handled by automatic machines and have excellent mass production, and can withstand high frequencies and large currents due to the proximity effect of the inner periphery, unlike planar coils. It has the advantage that there is no problem of heat generation. FIGS. 6A and 6B show a coil unit (first coil L ₁ and second coil L ₂ ) in which the transmission coil 14 is composed of a solenoid coil.

For example, in the case of an air-core single-turn coil with a track-shaped cross section as shown in Fig. 6(A), winding the coil wire is simple and easy, and the formed coil unit can also be configured in a small size. This has the advantage of being easy to connect to a heat sink.

Similarly, when the coil cross section is circular and the coil length is short compared to the coil diameter, such as the air-core single-turn coil in Figure 6 (B), the coil can be easily formed, the volume is small, and the inductance value can be increased. There are advantages that can be taken.

Although the frequency characteristics are deteriorated compared to an air-core single-turn coil, an air-core multilayer coil including an air-core two-layer coil may be used as long as there is no problem in use. In that case, there is an advantage that the coil length can be shortened.

1 Power supply device 10 Coil unit 11 Shield plate 12 Ferrite plate 13 Coil sheet 14 Transmission coil 15 Bobbin 16 Coil guide 16a Notch 17 Insulating sheet 20 Primary circuit 30 Secondary circuit 40 Control section 41 First resonance voltage detection circuit 42 Second resonant voltage detection circuit 43 First synchronous circuit 44 Second synchronous circuit 45 Control circuit 50 Metal exterior

Claims (5)

a coil unit including a first coil and a second coil;
a primary side circuit including a first capacitor and a first switch circuit, the first capacitor forming a first resonant circuit together with the first coil;
a secondary side circuit including a second capacitor and a second switch circuit, the second capacitor forming a second resonant circuit together with the second coil;
comprising a control unit;
The first coil and the second coil are fixed so as to face each other at a certain distance,
The control unit controls the first switch circuit and the second switch circuit so that the coil unit performs power transmission by magnetic field resonance ,
The first switch circuit includes a first switching element in which a first diode is connected in antiparallel,
The second switch circuit includes a second switching element in which a second diode is connected in antiparallel,
The power transmission includes forward power transmission from the primary circuit to the secondary circuit and reverse power transmission from the secondary circuit to the primary circuit,
The control unit includes:
At the time of the forward power transmission, the first switching element is controlled on and off, and the second switching element is turned off so that the second diode performs a rectification operation, and the output from the secondary circuit is controlled. a voltage difference between a first input voltage input to the primary side circuit and a first output voltage output from the secondary side circuit so that the power value of the first output power becomes a first target power value; While performing the first voltage difference control to control the
During the reverse power transmission, the second switching element is controlled on and off, and the first switching element is turned off so that the first diode performs a rectification operation, and the output from the primary circuit is controlled. a voltage difference between a second input voltage input to the secondary circuit and a second output voltage output from the primary circuit so that the power value of the second output power becomes a second target power value; Performs second voltage difference control to control
A power supply device characterized by: The power supply device according to claim 1 , wherein the first resonant circuit and the second resonant circuit are both parallel resonant circuits. Further equipped with heat dissipation material and metal exterior,
3. The power supply device according to claim 1, wherein the coil unit, the primary circuit, and the secondary circuit are housed in the metal exterior while being disposed on the heat dissipation material. 4. The first coil and the second coil are both planar coils or solenoid coils in which a coil wire is wound in two stages and no winding is formed on the inner periphery. Power supplies listed in section. The power supply device according to claim 4 , wherein the first coil and the second coil are planar coils,
A power supply device characterized in that the planar coil has an inner diameter that is 60% or more of the outer diameter of the coil.

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