JP2021168537A - Power supply device - Google Patents

Abstract

To provide a small-sized power supply device capable of outputting high power.SOLUTION: A power supply device comprises: a coil unit 10 including a first coil L1 and a second coil L2; a primary side circuit 20, which comprises a first capacitor C1 and a first switch circuit SW1, and in which the first capacitor C1 together with the first coil L1 constitutes a first resonance circuit; a secondary side circuit 30, which comprises a second capacitor C2 and a second switch circuit SW2, and in which a second capacitor C2 together with the second coil L2 constitutes a second resonance circuit; and a control part 40. The first coil L1 and the second coil L2 are fixed so as to face each other at a fixed distance D. The control part 40 controls the first switch circuit SW1 and the second switch circuit SW2 in such a manner that the coil unit 10 performs power transmission via magnetic field resonance.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power supply device.

Conventionally, as an isolated power supply device with several kilowatt output that performs DC / DC (direct current / direct current) voltage conversion, a phase shift full bridge type DC / DC converter, an LLC type DC / DC converter, and a DAB (dual active) A bidirectional DC / DC converter of the bridge) type is known. Switching elements and high frequency isolation transformers are used in these power supplies.

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

On the other hand, a high-frequency isolation transformer is a transformer that transmits power by electromagnetic induction, and a core material compatible with high frequencies such as manganese / zinc-based ferrite, manganese / nickel-based ferrite, amorphous material, and nanocrystal material is used as the core material. However, in general, an operation of about 100 kilohertz is a practical limit including material properties and cooling.

That is, in the conventional power supply device, the high frequency isolation transformer cannot keep up with the speeding up (high frequency) of the switching element, in other words, the characteristics such as high frequency and low loss due to the high frequency compatible power switching element such as SiC and GaN can be utilized. The problem is that it is not.

In addition, in conventional power supply devices, the size, cost, and weight of a high-frequency isolation transformer increase when it is used for several kilowatts, the efficiency decreases due to iron loss when the high-frequency isolation transformer is operated at high frequencies, and a heat sink for heat dissipation, etc. It is also a problem that the heat-dissipating material of the above becomes large.

Patent Document 1 describes a power supply device including an air-core transformer (air-core transformer) without a core material. Since the primary side of this power supply device is a series resonant circuit and the secondary side is a full-wave rectifying circuit (non-resonant circuit), the Q value of resonance is small. Further, 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 a limit of an output of about several watts, and cannot output a large amount of power of several kilowatts.

Special Table 2010-522535 Gazette

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a small-sized power supply device capable of outputting a large amount of electric power.

In order to solve the above problems, the power supply device according to the present invention
A coil unit including the first coil and the second coil,
A primary side circuit including a first capacitor and a first switch circuit, wherein the first capacitor and the first coil form a first resonance circuit.
A secondary side circuit including a second capacitor and a second switch circuit, wherein the second capacitor and the second coil form a second resonant circuit.
With a control unit
The first coil and the second coil are fixed so as to face each other at a fixed distance.
The control unit is characterized in that the first switch circuit and the second switch circuit are controlled so that the coil unit transmits electric power by magnetic field resonance.

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

In the above power supply
The first switch circuit is composed of a single first switching element in which a first diode is connected in antiparallel.
The second switch circuit is preferably composed of a single second switching element in which a second diode is connected in antiparallel.

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

The above power supply unit
With additional heat dissipation material and metal exterior,
The coil unit, the primary circuit, and the secondary circuit can be configured to be housed in the metal exterior in a state of being arranged on the heat radiating material.

In the above power supply
Both the first coil and the second coil may be a flat coil or a solenoid coil in which a coil wire is wound in two stages and no winding is formed in the inner peripheral portion.

According to the present invention, it is possible to provide a power supply device that is small in size and capable of outputting a large amount of electric power.

It is a circuit diagram of the power supply device which concerns on this invention. It is a perspective view of the coil unit which concerns on this invention. It is a figure which shows the bobbin and the coil guide of the coil unit which concerns on this invention. It is sectional drawing of the 1st coil and 2nd coil which concerns on this invention. It is sectional drawing of the 1st coil which concerns on a modification. It is a perspective view of the coil unit which concerns on a modification.

Hereinafter, embodiments of the 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 isolated DC / DC power supply device, and includes a coil unit 10, a primary side circuit 20, a secondary side circuit 30, a control unit 40, and a metal exterior 50. The power supply device 1 includes power transmission from the primary side circuit 20 to the secondary side circuit 30 (forward power transmission) and power transmission from the secondary side circuit 30 to the primary side circuit 20 (reverse power transmission). I do.

The power supply device 1 includes first input / output terminals T ₁₁ and T _12, and second input / output terminals T ₂₁ and 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 improvement) circuit. The second input / output ends 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 ends T ₁₁ , T _{12 and the primary side circuit 20, and the second input / output ends T 21} , T ₂₂ and the secondary side circuit are provided. A second filter circuit (for example, an LC filter circuit) may be provided between the 30 and the 30. 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 value.

Coil unit 10 includes a first coil L ₁ and the second coil L ₂ which is fixed so as to face at a fixed distance D. The first coil L ₁ and the second coil L ₂ are both flat coils in which a coil wire is wound in two stages. The detailed configuration 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 with the first coil L _1, constitute a (corresponding to the "first resonance circuit" of the present invention) a parallel resonant circuit together with the first coil L _1. The first switch means SW ₁ serves as a driving element for causing the first resonance circuit to resonate.

The secondary side circuit 30 includes a second capacitor C _{2 and a second switch means SW 2} corresponding to the “second switch circuit” of the present invention. The second capacitor C ₂ is connected in parallel to the second coil L _2, constitute a (corresponding to the "second resonance circuit" of the present invention) a parallel resonant circuit together with the second coil L _2. The second switch means SW ₂ serves as a driving element for causing the second resonance circuit to resonate.

The first switch means SW ₁ includes a first switching element Q ₁ connected in series to the first capacitor C ₁ and the first coil L ₁ , and a first diode D ₁ connected in antiparallel to the first switching element Q _1. including. The first diode D _1, the first built-in switching element Q ₁ (parasitic) diodes or the first switching element Q _1, is an independent diode.

The second switching means SW ₂ includes a second switching element Q ₂ connected in series to the second capacitor C ₂ and the second coil L ₂ , and a second diode D ₂ connected in antiparallel to the second switching element Q _2. including. The second diode D ₂ is built (parasitic) diode of the second switching element Q ₂ or the second switching element Q _2, it is an independent diode.

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

The first coil L ₁ and the primary side circuit 20 are single-ended converters that operate with a single _{driving element (first switch means SW 1).} Similarly, the second coil L ₂ and the secondary side circuit 30 are single-ended converters that operate with a single _{drive element (second switch means SW 2).} With such a configuration, it is possible to reduce the cost, reduce the mounting space, and simplify the control. In the case of less than the current allowable current capacity of the first switch means SW ₁ and the second switch means SW ₂ is required, if the first switch means SW ₁ and the second switch means SW ₂ respectively connecting in parallel a plurality Also included.

The control unit 40 includes a first resonance voltage detection circuit 41, a second resonance voltage detection circuit 42, a first synchronization circuit 43, a second synchronization circuit 44, and a control circuit 45. The first synchronization circuit 43 includes _{a drive circuit (gate drive circuit) of the first switch means SW 1} , and the second synchronization circuit 44 includes a drive circuit (gate drive circuit) of the second switch means SW ₂ .

First resonance voltage detection circuit 41, first to measure the voltage across V _R1 of the capacitor C _1, to detect the zero crossing point of the resonance voltage of the first resonant circuit. The first resonance voltage detection circuit 41 that has detected the zero cross point outputs a zero cross signal to the first synchronous circuit 43.

The second resonance voltage detection circuit 42 measures the voltage _{VR2 across the second capacitor C 2} and detects the zero crossing point of the resonance voltage of the second resonance circuit. The second resonance voltage detection circuit 42 that has detected the zero cross point outputs a zero cross signal to the second synchronous circuit 44.

First synchronizing circuit 43, during forward power transmission, in synchronization with the resonance voltage of the first resonant circuit (in this embodiment, in synchronization with the zero-cross signal) of the first switching element Q ₁ at the zero-voltage switching operation turns on, turning off the first switching element Q ₁ after the lapse of a preset on-time. Further, the first synchronous circuit 43 turns off _{the first switching element Q 1} so that the rectifying operation by _{the first diode D 1} is performed under the control of the control circuit 45 during the reverse power transmission.

The second synchronous circuit 44 turns off _{the second switching element Q 2} so that the rectifying operation by _{the second diode D 2} is performed under the control of the control circuit 45 during the forward power transmission. The second synchronizing circuit 44 is also at the time of reverse power conversion, in synchronization with the resonance voltage of the second resonance circuit (in this embodiment, in synchronization with the zero-cross signal) and the second switching element Q ₂ zero-voltage switching operation in turns on, turning off the second switching element Q ₂ after the lapse of a preset on-time.

The control circuit 45 has a voltage difference (first voltage) between _{the first input voltage E 1} input to the primary side circuit 20 and _{the first output voltage E 2} output from the secondary side circuit 30 during forward power transmission. The first voltage difference control for controlling the difference) is performed.

The control circuit 45, a first voltage difference control is started in response to the control command signals S ₁ from the outside. The control circuit 45 that has started the first voltage difference control has a voltage value of the first input voltage E _{1 based on the first detection signal S 2 of the first detection means X 1} (for example, the current transformer) in a predetermined cycle. And / or obtains the current value of the first input current flowing between the first input / output terminals T ₁₁ and T _{12 and the primary side circuit 20.} Further, the control circuit 45 acquires information on the output power output from the secondary circuit 30 at a predetermined cycle. Information about the output power, the power value of the output power, the first output voltage voltage value and power value of the output power of the E ₂ or first output voltage voltage value and the second input-output terminal T _21, T ₂₂ of E _2, It is a current value of the first output current flowing between the secondary side circuit 30 and the secondary side circuit 30.

The control circuit 45 acquires the necessary information as described above, and 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. controlling the first input voltage E ₁ outputs a voltage command signal S ₃ to the conversion circuit or PFC circuit. That is, the control circuit 45 controls the first voltage difference by controlling the first input voltage E _1.

During forward power transmission, the control circuit 45 performs a first voltage difference control, the first synchronizing circuit 43 performs the first on-off control of the switching element Q _1, the first coil L ₁ and the first capacitor C ₁ Current flows. As a result, a current due to magnetic field resonance (synonymous with magnetic field resonance, magnetic resonance, magnetic resonance) flows through _{the second coil L 2} and the second capacitor C ₂ separated by a certain distance. As a result, non-contact (transformerless) power transmission is performed from the primary side circuit 20 to the secondary side circuit 30.

Further, the control circuit 45 has a voltage difference (second) between _{the second input voltage E 2 input to the secondary circuit 30 and the second output voltage E 1} output from the primary circuit 20 during reverse power transmission. The second voltage difference control for controlling the voltage difference) is performed.

The control circuit 45, a second voltage difference control is started in response to the control command signals S ₁ from the outside. The control circuit 45 that has started the second voltage difference control has a 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, the current transformer) in a predetermined cycle. And / or obtains the current value of the second input current flowing between the second input / output ends T ₂₁ , T _{22 and the secondary side circuit 30.} Further, the control circuit 45 acquires information on the output power output from the primary side circuit 20 at a predetermined cycle. Information about the output power, the power value of the output power, and the second output voltage voltage value and power value of the output power of the E ₁ and the second output voltage voltage value and the first input-output terminal T _11, T ₁₂ of E _1, It is a current value of the second output current flowing between the primary side circuit 20 and the primary side circuit 20.

Control circuit 45, while obtaining the required information as described above, as the power value of the output power becomes a predetermined target power value, and outputs a voltage command signal S ₃ to the control apparatus for a DC load or battery The second input voltage E ₂ is controlled. That is, the control circuit 45 controls the second voltage difference by controlling _{the second input voltage E 2.} The control circuit 45 has a first input-output terminal _{T 11, T 12} connected AC / DC conversion circuit or the PFC circuit second controls the output voltage _{E 1} outputs a voltage command signal _{S 3} to the (e.g., the 2 The second voltage difference may be controlled by lowering or raising the output voltage E ₁ from the second input voltage E _2).

In the reverse power transmission, performs the control circuit 45 is a second voltage difference control, the second synchronizing circuit 44 performs the second on-off control of the switching element Q _2, the second coil L ₂ and the second capacitor C ₂ Current flows. As a result, a current due to magnetic field resonance flows through _{the first coil L 1} and the first capacitor C ₁ separated by a certain distance. As a result, non-contact power transmission is performed from the secondary circuit 30 to the primary circuit 20.

The metal exterior 50 includes a heat radiating material (for example, a heat sink) inside or outside the metal exterior 50. The coil unit 10, the primary side circuit 20, the secondary side circuit 30, and the control unit 40 are appropriately housed in the metal exterior 50 in a state of being arranged on a heat radiating material (for example, a heat sink) as needed. In particular, since the coil unit 10 is housed in the metal exterior 50, the external space is not used for the transmission line of power transmission, so that it does not fall under the regulations of the Radio Law, and the leakage magnetic field and radiation noise are also the same as those of a normal power supply device. It is possible to limit 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 fixed 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 having a large volume and weight, it can be miniaturized. Further, the power supply device 1 according to the present embodiment is smaller and lower than the bridge type converter because the primary side circuit 20 and the secondary side circuit 30 are single-ended converters that operate with a single drive element. Cost reduction is possible.

In the power supply device 1 according to the present embodiment, since the coil unit 10 transmits electric power by magnetic field resonance, it is possible to output a large amount of electric power of, for example, several kilowatts. Further, in the power supply device 1, the decrease in the coupling coefficient due to the coil unit 10 not having a core can be compensated for by the Q value of resonance that is increased by the coil unit 10 performing magnetic field resonance. As a result, the power supply device 1 can obtain high transmission efficiency equal to or higher than that of the power supply device provided with the high frequency isolation transformer.

[Coil unit configuration]
_{The coil unit 10 includes a first coil L 1} and a second coil L ₂ fixed so that the coil surfaces are parallel to each other at a constant distance D and the central axes perpendicular to the coil surfaces face each other on the same line. Constant distance D, at a short distance compared to the general non-contact power transmission, so that the coupling coefficient of the first coil L ₁ and the second coil L ₂ is a value within the range of about 0.3 to 0.7 Is set to. For example, when the _{outer diameters of the first coil L 1} and the second coil L ₂ are 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 a value. In this case, the coil unit 10 has a volume of about 1/2 and a weight of 1/2 or less as compared with the conventional high-frequency isolation transformer for several kilowatts.

In the case of a wireless charging system in which one coil is provided in an electric vehicle (power receiving device) and the other coil is provided in a power feeding device, the distance between one coil and the other coil is 30 [mm] or more (for example, 45 [. mm]) The coupling coefficient between the coils is a value within the range of about 0.1 to 0.3, and the outer diameter of the coil is as large as several hundreds [mm]. Moreover, the wireless charging system has a problem that the distance between the coils changes when the height of the electric vehicle 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 is separated or deviated from the center position, the coupling coefficient between the coils is lowered and the transmission efficiency is lowered.

On the other hand, as described above, the coil unit 10 is fixed and used in a state where the center positions of the coils are aligned at a constant distance D, so that the outer diameter of the coil is about 120 [mm] and the size is reduced to a fraction. Therefore, the coupling coefficient is about 0.3 to 0.7, which is 2 to 3 times higher, so the efficiency is improved, and since the position is fixed, it can be used with the best efficiency, and the coupling coefficient changes. There is an advantage that complicated control is not required.

FIG. 2 shows a perspective view of the coil unit 10. The coil unit 10 includes a first coil L ₁ and a second coil L _2, and a fixing member (not shown) that fixes them at a fixed 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 L ₂ has the same configuration as the first coil L _1. The first coil L ₁ and the second coil L ₂ are fixed at a constant distance D so that the transmission coils 14 face each other. The shield plate 11, the coil sheet 13, and the 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 radiating member (for example, a heat sink) may be connected to the shield plate 11. By connecting the heat radiating member, the copper loss heat generated from the transmission coil 14 due to heat conduction can be efficiently diffused to the outside through the heat radiating member.

The ferrite plate 12 is made larger than the transmission coil 14, forms a magnetic path so that magnetic flux does not go out, and is provided to improve the coupling coefficient, and is arranged inside the shield plate 11. A heat radiating 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 rod-shaped plate arranged radially, or a ferrite plate block may be spread over the ferrite plate 12. Instead of the ferrite plate 12, a member made of another magnetic material such as an amorphous material or a nanocrystal material may be used. By making the ferrite plate 12 larger than the transmission coil 14 (for example, by making the diagonal length of the ferrite plate 12 larger than the coil outer diameter of the transmission coil 14), the transmission coil 14 is provided with the shield plate 11. The effect of the decrease in inductance and coupling coefficient is reduced.

The coil sheet 13 is arranged inside the 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 having high heat dissipation (for example, a heat dissipation sheet) or by forming the coil sheet 13 with a material having high heat dissipation, 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 rod wound in a spiral shape and is arranged inside the coil sheet 13. As the coil wire of the transmission coil 14, a litz wire or a flat wire may be used in order to reduce the skin effect at high frequencies. Although the shape of the transmission coil 14 is circular, any shape can be used as long as the required inductance and the coupling coefficient having a value within the range of about 0.3 to 0.7 can be obtained. Can be done. For example, it may be rectangular and has arcuate corners, or it may be elliptical or a track having a straight portion in the major axis direction.

However, in a flat bulk (sheet) coil, it is known that heat generation due to Joule loss in the inner peripheral portion of the coil becomes remarkable due to the influence of a magnetic field (proximity effect) generated by an induced current flowing in the outer peripheral portion of the coil. .. Such a phenomenon is not usually a problem with litz wires, but is particularly problematic with a magnetic field resonant circuit in which a large resonant current flows through the coil at high frequencies and with a small planar coil. That is, it does not matter in the case of a large coil for an electric vehicle composed of litz wire, but in the case of the coil unit 10 of the present embodiment which is a small flat coil, the influence of the magnetic field generated by the induced current flowing in the outer peripheral portion of the coil. In (proximity effect), heat generation due to Joule loss in the inner circumference of the coil becomes remarkable. Therefore, in the coil unit 10, the bobbin 15 is used to provide the inner peripheral portion (inner diameter) of the coil on the transmission coil 14 so that the coil (winding) is not formed on the inner peripheral portion of the coil. In this case, it is preferable that the transmission coil 14 is provided with an inner diameter of 60% or more of the coil outer diameter, for example, an inner diameter of about 2/3 of the coil outer diameter.

In the case of a coil for an electric vehicle, the ground-side large-vehicle is small, its characteristics (wire, inductance, resistance, etc.) are different, the first transmission coil L ₁ and the second coil L ₂ of the present embodiment Since the coil 14 is used by being fixed face-to-face in a state where the center positions of the coils are aligned at a fixed distance D, the coil 14 may have the same size and the same characteristics, and is excellent in productivity.

The bobbin 15 is provided to facilitate winding of the transmission coil 14, and is arranged at the center of the transmission coil 14. The bobbin 15 is provided with a non-magnetic, 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 in} a plane passing through the center line. As shown in FIG. 4, the method of winding the transmission coil 14 starts 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 winds on the upper side of the coil guide 16 (coil sheet 13). This is a winding method in which the 2nd and 3rd windings (on the far side from the side) are wound, and then the 4th and 5th windings on the lower side of the coil guide 16 are wound in this order. The transmission coil 14 moves between the upper side and the lower side via the notch portion 16a.

In this winding method, transmission coils 14 having continuous winding orders are arranged adjacent to each other, and transmission coils 14 having different winding orders are arranged so as not to be adjacent to each other. It makes it difficult for dielectric breakdown to occur due to the voltage difference between the two. With this winding method, the coil wire of the transmission coil 14 can be made of a thin insulating coating, so that the transmission coil 14 can be made smaller, lighter, and less costly.

Since the transmission coil 14 is a flat coil having a two-layer (two-column) structure with the coil guide 16 interposed therebetween, it is smaller than a flat coil having a single-layer structure. Nevertheless, the transmission coil 14 is a compact coil that can obtain the required inductance, has a high coupling coefficient, and has good transmission efficiency. Further, the transmission coil 14 is a small coil capable of preventing remarkable heat generation in the inner peripheral portion of the coil while having a small outer diameter even in a magnetic field resonance circuit in which a large resonance current flows at a high frequency. Become.

The conventional high-frequency isolation transformer for several kilowatts has a closed three-dimensional structure in which heat generation due to iron loss and copper loss of the coil is difficult to be transmitted to the outside, so that heat dissipation is not good. On the other hand, since the coil unit 10 has a coreless structure without a core, it does not generate heat due to iron loss. Further, in the coil unit 10, since the transmission coil 14 is a flat coil, heat generation due to 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, the loss due to the high frequency of the core material, which has been a problem in the high frequency isolation transformer, does not occur. Therefore, when the power supply device 1 including the coil unit 10 uses a power switching element compatible with high frequencies such as SiC and GaN as _{the first switching element Q 1} and the second switching element Q _{2, the high frequency generated by the power switching element is used.}・ Characteristics such as low loss can be utilized. As a result, the power supply device 1 according to the present 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 1/2 or less as compared with a high-frequency isolation transformer for several kilowatts. Therefore, the power supply device 1 according to the present embodiment can be reduced in size, weight, and cost.

By downsizing the coil unit 10, it is possible to reduce the loss (improvement of efficiency) due to the decrease in the resistance value of the transmission coil 14 and the cost reduction by reducing the expensive coil wire material such as the litz wire used for the transmission coil 14.

In the coil unit 10, since the first coil L ₁ and the second coil L ₂ are fixed at a constant distance D, the efficiency does not decrease due to a change in the coupling coefficient, so that the control circuit 45 has a special efficiency. No reduction measures are required. Therefore, it is easy to adjust the control parameters during the control of the control circuit 45 (for example, during the first voltage difference control and the second voltage difference control), and it is possible to operate under the control conditions with the highest transmission efficiency. ..

In the present embodiment, the first coil L ₁ and the second coil L ₂ separated by a certain distance D are fixed in a vertically standing state, but the first coil L ₁ and the second coil separated by a certain distance D are fixed. L ₂ may be fixed in a horizontally laid state.

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

[Modification 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 the first capacitor and the first coil form a first resonance circuit on the primary side. The first coil and the second coil include a circuit, a secondary side circuit including a second capacitor and a second switch circuit, the second capacitor forming a second resonance circuit together with the second coil, and a control unit. The control unit is fixed so as to face each other at a fixed distance, and the configuration of the control unit can be appropriately changed as long as it controls the first switch circuit and the second switch circuit so that the coil unit transmits power by magnetic field resonance.

For example, the control unit 40 of the above embodiment may perform control by the voltage difference of the input / output voltage including the first voltage difference control and the second voltage difference control, _{or the first switch means SW 1} (or the first switching). Phase shift control may be performed to control the switching of the element Q ₁ ) and the switching of the second switching means SW ₂ (or the second switching element Q ₂ ) so as to have a predetermined phase difference.

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

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, the configuration of a single-ended converter as in the above embodiment is preferable.

5 (A) to 5 (E) show cross-sectional views of the coil unit 10 according to the modified example. Since the second coil L ₂ has the same configuration as the first coil L ₁ , it is omitted.

In the winding method of FIG. 5A, the winding is started from the lower No. 1 of the coil guide 16 along the bobbin 15, the upper No. 2 of the coil guide 16 is wound, and then the lower No. 3 and the upper No. 4 are wound. It is a winding method in which the winding is performed alternately in the order of the numbers. In this winding method, similarly to the winding method of the above embodiment, the transmission coils 14 having continuous winding orders are arranged adjacent to each other, and the transmission coils 14 having different winding orders are arranged so as not to be adjacent to each other. This is intended to prevent dielectric breakdown due to a voltage difference between the coil wires of the transmission coils 14 separated from each other.

The winding method of FIG. 5B is as follows: along the bobbin 15 without the coil guide 16, the lower No. 1 and No. 2 are wound, the upper No. 3 and No. 4 are wound, and then the lower No. 5 is wound. It is a winding method that winds in the order of No. 6. In this winding method, as compared with the winding method of the above embodiment, the transmission coils 14 having a continuous winding order are slightly separated from each other, but the lower side is wound and then the upper side is wound, so that the winding method becomes easier.

The winding method of FIG. 5C is as follows: along the bobbin 15 without the coil guide 16, the lower No. 1 is wound, the lower No. 2 is wound on the bobbin 15, the lower No. 3 and the upper No. 4 are alternately wound. It is a winding method that winds around. This winding method is simple, and since the upper transmission coil 14 is wound on the lower transmission coil 14, it becomes easier to wind.

The winding method of FIG. 5D is a two-layer alpha winding, in which the lower first layer is wound from the outer circumference toward the center (bobbin 15), and the upper second layer is wound from the center (bobbin 15) to the outer circumference. It is a winding method that winds toward. In the case of this winding method, the transmission coil 14 can be efficiently manufactured by using the alpha winding machine. When winding using an alpha winding automatic machine, a litz wire having 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 of FIG. 5 (E) is a two-layer alpha winding method in which a non-magnetic insulating sheet 17 is sandwiched between the first layer and the second layer. In the configuration of FIG. 5 (D) (the configuration of only the alpha-wound two-layer coil), since the number of turns is continuous between the coil wires in the same layer, there is no problem in terms of breakdown voltage, but there is no problem in terms of breakdown voltage, but another layer (one-layer to two-layer). ), Since the number of turns is different, there is a possibility that a withstand voltage problem such as dielectric breakdown may occur. On the other hand, in the configuration of FIG. 5 (E), since the dielectric breakdown is strengthened by sandwiching the insulating sheet 17, the transmission coil 14 can be efficiently manufactured by using the alpha winding machine. Moreover, it is possible to prevent dielectric breakdown from occurring.

The transmission coil of the present invention is not limited to a two-layer structure (two-stage structure), and may be a flat coil having a structure of one layer or three or more layers. If the coil inductance required in the coil unit 10 fits in the desired coil size, a single-layer structure may be used, but if it does not fit, it is desirable to use a structure having two or more layers and fit 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 flat coil, and may be a solenoid coil as long as it has a desired inductance and a small coil size. In the case of a solenoid coil, even in the case of single winding and multi-layer winding, it is easy for automatic machines to handle, it is excellent in mass productivity, and the inner circumference part due to the proximity effect like a flat coil even for high frequency and large current. There is an advantage that there is no problem of heat generation. 6 (A) and 6 (B) show coil units (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-wound coil having a track-shaped cross section as shown in FIG. 6 (A), it is simple and easy to wind the coil wire, and the formed coil unit can also be made compact. It 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 shorter than the coil diameter as in the air-core single-wound coil shown in FIG. 6B, coil molding is easy, the volume is small, and the inductance value is large. There is an advantage that can be taken.

Although the frequency characteristics are deteriorated as compared with the air-core single-wound coil, if there is no problem in use, an air-core multi-layer winding coil including an air-core two-layer winding coil may be used. In that case, there is an advantage that the coil length can be shortened.

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

Claims (6)

A coil unit including the first coil and the second coil,
A primary side circuit including a first capacitor and a first switch circuit, wherein the first capacitor and the first coil form a first resonance circuit.
A secondary side circuit including a second capacitor and a second switch circuit, wherein the second capacitor and the second coil form a second resonant circuit.
With a control unit
The first coil and the second coil are fixed so as to face each other at a fixed distance.
The control unit is a power supply device that controls the first switch circuit and the second switch circuit so that the coil unit transmits electric power by magnetic field resonance. The first switch circuit is composed of a single first switching element in which a first diode is connected in antiparallel.
The power supply device according to claim 1, wherein the second switch circuit is composed of a single second switching element in which a second diode is connected in antiparallel. The power supply device according to claim 1 or 2, wherein the first resonance circuit and the second resonance circuit are both parallel resonance circuits. With additional heat dissipation material and metal exterior,
The invention according to any one of claims 1 to 3, wherein the coil unit, the primary circuit, and the secondary circuit are housed in the metal exterior in a state of being arranged on the heat radiating material. The power supply described. Any one of claims 1 to 4, wherein the first coil and the second coil are both a flat coil or a solenoid coil in which a coil wire is wound in two stages and no winding is formed on the inner peripheral portion. The power supply as described in the section. The power supply device according to claim 5, wherein the first coil and the second coil are flat coils.
The flat coil is a power supply device having an inner diameter of 60% or more with respect to the outer diameter of the coil.

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