JPWO2016135893A1 - Control device, power transmission device, power reception device, wireless power transmission device, and control method - Google Patents

Abstract

Radiation emission generated during wireless power transmission is reduced. A control device according to an embodiment of the present invention is a control device that controls a wireless power transmission device including a power transmission unit and a power reception unit, and includes a first control unit. The power transmission unit includes a first power transmission coil unit and a second power transmission coil unit. The power receiving unit includes a first power receiving coil unit, a second power receiving coil unit, a first rectifier, a first DC-DC converter, a second rectifier, and a second DC-DC conversion. And a vessel. The controller is configured to control the first DC-DC based on a first detection value related to a current amplitude of the first power transmission coil unit and a second detection value related to a current amplitude of the second power transmission coil unit. At least one of a voltage conversion ratio of the converter and a voltage conversion ratio of the second DC-DC converter is controlled.

Description

  Embodiments described herein relate generally to a control device, a power transmission device, a power reception device, a wireless power transmission device, and a control method.

  In wireless power transmission, power is transmitted by supplying an alternating current to a coil on the power transmission side and coupling an electromagnetic field generated by the coil on the power transmission side to the coil on the power reception side. It is known that radiated emissions are generated by electromagnetic fields generated in the coils on the power transmission side and the power reception side. To reduce this, two coils are used on the power transmission side and the power reception side, respectively, and the coil on the power transmission side is reversed. A method of driving with a phase voltage has been proposed. As a result, the electromagnetic field generated from the coil on the power transmission side can be offset and canceled out, so that radiated emissions can be reduced.

  However, in this method, the inductance of the coil, the characteristics of the components connected to the coil, the characteristics of the counter device (the power receiving side device for the power transmission side, the power transmission side device for the power receiving side), and the positional relationship with the counter device If all are not symmetrical, the amplitudes of the currents flowing through the coils are not the same. Thereby, the subject that the reduction effect of a radiation emission was restrict | limited occurred.

Patent registration No. 5139469

  Embodiments of the present invention aim to reduce radiated emissions in wireless power transmission.

  A control device as an embodiment of the present invention is a control device that controls a wireless power transmission device including a power transmission unit and a power reception unit, and includes a first control unit.

  The power transmission unit includes a first power transmission coil unit including a first power transmission coil and a capacitor connected in series to the first power transmission coil, a second power transmission coil, and the second power transmission coil in series. A second power transmission coil unit including a connected capacity.

The power receiving unit includes a first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil, a second power receiving coil, and the second power receiving coil in series. A second power receiving coil unit including a connected capacitor, a first rectifier that converts power received by the first power receiving coil unit into direct current, and direct current power converted by the first rectifier. A first DC-DC converter for DC-DC conversion of the voltage, a second rectifier for converting the electric power received by the second power receiving coil unit into a direct current, and a direct current converted by the second rectifier And a second DC-DC converter for DC-DC converting the voltage of the power.

  The absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is greater than the absolute value of the coupling coefficient between the first power transmission coil and the second power reception coil, and the second The absolute value of the coupling coefficient between the power transmission coil and the second power receiving coil is larger than the absolute value of the coupling coefficient between the second power transmission coil and the first power receiving coil.

  The controller is configured to control the first DC-DC based on a first detection value related to a current amplitude of the first power transmission coil unit and a second detection value related to a current amplitude of the second power transmission coil unit. At least one of a voltage conversion ratio of the converter and a voltage conversion ratio of the second DC-DC converter is controlled.

The block diagram of the wireless power transmission apparatus provided with the control apparatus which concerns on 1st Embodiment. Explanatory drawing of the definition of relative magnetic field intensity. The figure which shows the magnetic field relative intensity in a certain observation point on ay axis. The figure which shows the magnetic field relative intensity in a certain observation point on an x-axis. The figure which shows the magnetic field relative intensity in the other observation point on an x-axis. 1 is a configuration diagram of a one-system wireless power transmission device. FIG. The figure which shows the example of the graph of the relationship between the voltage conversion ratio of a DC-DC converter, and the power transmission coil unit current in the structure of FIG. The figure which shows the example of the filter circuit which operate | moves as an impedance inverter. The figure which shows an example of the operation | movement flow which changes the voltage conversion ratio of a DC-DC converter. The figure which shows an example of another operation | movement flow which changes the voltage conversion ratio of a DC-DC converter. The figure which shows the other structural example of a power transmission coil unit. The figure which shows a structure provided with alternating current power supply and load for every system | strain. The figure which shows the structural example of alternating current power supply. The block diagram in the case of detecting the amplitude of DC current. The figure which shows the structural example of a rectifier. The circuit diagram which shows the example of a DC-DC converter. The circuit diagram which shows the other example of a DC-DC converter. The circuit diagram which shows the further another example of a DC-DC converter. The circuit diagram which shows the further another example of a DC-DC converter. The figure which shows the example of the structure which transmits a conversion ratio adjustment signal on radio. The figure which shows the example of the structure which transmits the detection value of a current amplitude detection part wirelessly. The block diagram of the wireless power transmission apparatus which concerns on 2nd Embodiment. The block diagram of the wireless power transmission apparatus which concerns on 3rd Embodiment. The figure which shows the example of the graph of the relationship between the amplitude of AC power supply, and the electric current of a receiving coil unit in the structure of FIG. The figure which shows the example of the graph of the relationship between the amplitude of alternating current power supply at the time of connecting a battery as load in the structure of FIG. 6, and the electric current of each coil unit of power transmission and power reception. The figure which shows the example of the graph of the relationship between the voltage conversion ratio of the DC-DC changer in the structure which connected the battery as load in the structure of FIG. 6, and the electric current of each coil unit of power transmission and reception. The figure which shows the structural example which connected the current amplitude detector to the back | latter stage of the rectifier.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 shows a wireless power transmission device including a control device according to the first embodiment.

  The wireless power transmission device includes a power transmission unit 20, a power reception unit 30, and a control device.

  The power transmission unit 20 includes an AC power source 21, a power transmission coil unit 1 (221), and a power transmission coil unit 2 (222).

  The AC power supply 21 outputs an AC voltage including a fundamental frequency component. The fundamental frequency is a frequency mainly contributing to power transmission, and can be arbitrarily set. The waveform of the AC voltage including the fundamental frequency component is, for example, a sine wave of the fundamental frequency or a rectangular wave having the same period as the fundamental frequency.

  Two power transmission coil units 221 and 222 are connected to the AC power source 21 in parallel. The power transmission coil unit 221 includes a capacitor 281 and a power transmission coil (hereinafter referred to as a coil) 291. The capacitor 281 and the coil 291 are connected in series. The power transmission coil unit 222 includes a capacitor 282 and a power transmission coil (hereinafter referred to as a coil) 292, and the capacitor 282 and the coil 292 are connected in series. The resonance frequency of the series resonance circuit of the capacitor 281 and the coil 291 and the resonance frequency of the series resonance circuit of the capacitor 282 and the coil 292 are set to be the same as or substantially the same as the fundamental frequency. The power transmission coil units 221 and 222 are supplied with an alternating current from the alternating current power source 21 and wirelessly generate power by coupling an electromagnetic field generated due to a current flowing through the coils 291 and 292 to the coils 391 and 392 on the power receiving side. Is transmitted to the power receiving side.

  The power receiving unit 30 includes a power receiving coil unit 1 (311), a rectifier 321, a DC-DC converter 331, and a power receiving coil unit 2 (312), a rectifier 322, and a DC-DC converter 332.

  The power receiving coil unit 311 receives power wirelessly from the power transmission side. The rectifier 321 is connected to the power receiving coil unit 311 and converts AC power received by the power receiving coil unit 311 into DC power. The DC-DC converter 331 is connected to the rectifier 321, and converts the DC power converted by the rectifier 321 with a preset conversion ratio (DC-DC conversion).

  The power receiving coil unit 312 receives power wirelessly from the power transmission side. The rectifier 322 is connected to the power receiving coil unit 312 and converts AC power received by the power receiving coil unit 312 into DC power. The DC-DC converter 332 is connected to the rectifier 322, and converts the DC power converted by the rectifier 322 with a preset conversion ratio (DC-DC conversion).

  The outputs of the DC-DC converters 331 and 332 are both connected to the load 34. The load 34 is an arbitrary device that consumes the electric power converted by the DC-DC converter 331 or an arbitrary device that accumulates the electric power. Here, the load 34 is a part of the power receiving unit 30, but the load 34 may be an element outside the power receiving unit 30.

  Here, the power receiving coil unit 311 includes a capacitor 381 and a power receiving coil (hereinafter referred to as a coil) 391, and the capacitor 381 and the coil 391 are connected in series. The power receiving coil unit 312 includes a capacitor 382 and a power receiving coil (hereinafter referred to as a coil) 392, and the capacitor 382 and the coil 392 are connected in series. The resonance frequency of the series resonance circuit of the capacitor 381 and the coil 391 and the resonance frequency of the series resonance circuit of the capacitor 382 and the coil 392 are set to be the same or substantially the same as the fundamental frequency.

  The coils 291, 292, 391 and 392 have mutual coupling with each other, and power is transmitted through the mutual coupling. Two couplings of the coil 291 and the coil 391 and the coil 292 and the coil 392 are defined as main coupling. The main coupling is stronger than the other couplings, that is, the couplings of the coil 291 and the coil 392, the coil 292 and the coil 391, the coil 291 and the coil 292, and the coil 391 and the coil 392. Strong coupling means that the absolute value of the coupling coefficient is large. In wireless power transmission, power transmission via the main coupling is dominant.

  Here, “system 1” and “system 2” are defined as power transmission paths by main coupling. The system 1 is a path including the power transmission coil unit 1, the power reception coil unit 1, the rectifier 321, and the DC-DC converter 331. The system 2 is a path including the power transmission coil unit 2, the power reception coil unit 2, the rectifier 322, and the DC-DC converter 332.

  The control device includes a current amplitude detection unit 511, a current amplitude detection unit 512, and a power transmission current amplitude control unit (first control unit) 52. The control device may exist as a single device independent of the power transmission unit 20 and the power reception unit 30. Alternatively, the control device may be incorporated in the power transmission unit 20 to constitute a part of the power transmission device. The control device may be incorporated in the power reception unit 30 to constitute a part of the power reception device.

  The current amplitude detector 511 detects a value related to the amplitude of the input current of the power transmission coil unit 221. The current amplitude detector 512 detects a value related to the amplitude of the input current of the power transmission coil unit 222. The value to be detected may be an arbitrary unit as long as it is a value related to the AC current amplitude correlated with the magnetic field generated from the coils 291 and 292, such as current amplitude and rms value. The current amplitude detection units 511 and 512 output the detected values to the transmission current amplitude control unit 52.

  The transmission current amplitude control unit 52 compares the outputs of the current amplitude detection units 511 and 512, and generates the conversion ratio adjustment signal 1 and the conversion ratio adjustment signal 2 according to the comparison result. The transmission current amplitude control unit 52 is connected to the DC-DC converters 331 and 332 of the power reception unit via wires such as cables, and the conversion ratio adjustment signals 1 and 2 are converted into the DC-DC converters 331 and 332. Output to. The conversion ratio adjustment signal is a signal instructing conversion of the DC-DC converter, and the DC-DC converter performs DC-DC conversion at a voltage conversion ratio corresponding to the conversion ratio adjustment signal. The voltage conversion ratio is defined as, for example, the output voltage from the DC-DC converter / the input voltage of the DC-DC converter, but is not limited thereto.

  Based on the output values of the current amplitude detection unit 511 and the current amplitude detection unit 512, the transmission current amplitude control unit 52 outputs the conversion ratio adjustment signal 1 and the conversion ratio adjustment signal 2 so that the radiation emission at the observation point is reduced. Generate. The observation point means a part where the radiated emission is to be reduced or a part within a region where the radiated emission is desired to be reduced. The reason why radiation emission can be reduced by controlling the voltage conversion ratio of the DC-DC converter will be described later.

  Radiation emission is generated by a magnetic field generated in proportion to the current flowing through the coil of each power transmission coil unit. Radiation emissions have a standard that should be met by standards, etc., so it is desirable to keep them low. In order to reduce the radiated emission at the observation point, the radiated emission from each power transmission coil unit may be canceled at the observation point.

  If the magnetic fields generated from the coil 291 and the coil 292 are approximately opposite in phase and approximately the same amplitude, the magnetic field cancels out (ie, at a position that is symmetrical from the two coils or far away from the distance between the two coils). Radiated emissions are offset). As a result, it is expected that radiated emissions are reduced as compared with the case where a magnetic field is generated in phase from the two coils.

As a general approximation, the magnetic field is considered to be proportional to the coil current and the inductance (L), and the magnetic field is attenuated in inverse proportion to the cube of the distance from the coil center. When the magnitudes of the magnetic fields generated from the two coils are both H ₀ and in phase, the phase difference of the magnetic fields generated from the two coils is 180 + Φ [degree], and the magnetic field generated from the two coils The relative value (relative electromagnetic field strength) of the magnetic field at the observation point when the average value of magnitude is H ₀ and the difference is Δ [%] is obtained.

The difference in the magnitude of the magnetic field is Δ [%], where the magnetic field generated from one side is given by H ₀ (1−Δ / 200), and the magnetic field generated from the other side is given by H ₀ (1 + Δ / 200). Refer to the case.

ｒ_１はコイル１、２のそれぞれの中心から点Ａまでの距離である。As shown in FIG. 2, it is assumed that the centers of the two coils are equidistant from the origin to the x axis in opposite directions. The y-axis represents a point equidistant from the center of the two coils. Let d be the distance between the centers of the two coils. In such an xy orthogonal coordinate system, a point (0, r ₀ ) on the y-axis is considered as the observation point A. At this time, the magnetic field intensity at the observation point A is given by vector synthesis of magnetic fluxes generated from the two coils. Since the magnitude of the magnetic flux generated from each coil is inversely proportional to the cube of the distance, the relative magnetic field strength Ha at the observation point A can be calculated as follows.

r ₁ is the distance from the center of each of the coils 1 and 2 to the point A.

式（２）は、ｒ_１に依存しないため、ｙ軸上では観測位置によらず同じ低減効果が得られることが理解される。When the equation (1) is transformed, the relative magnetic field strength Ha is expressed by the following equation (2).

Since equation (2) does not depend on r ₁ , it is understood that the same reduction effect can be obtained on the y-axis regardless of the observation position.

  FIG. 3 is a diagram in which the expression (2) is expressed in dB and plotted against the deviation (Φ) from the phase difference of 180 degrees and the difference in magnetic field magnitude (Δ (%)). It can be seen that in order to obtain a reduction effect by cancellation of about 10 dB, Φ should be suppressed to about 30 degrees and Δ should be suppressed to about 40%.

Next, as the observation point B, as shown in FIG. 2, a point (r ₀ , 0) on the x-axis is considered. At this time, the relative magnetic field strength Hb is given as follows.

At the observation point B, the magnetic field strength depends on r ₀ , but if it is far away from the power transmission unit, r ₀ >> d, and therefore it can be said that equation (3) can be approximated to equation (2).

FIG. 4 shows a plot of Φ and Δ when Equation (2) is expressed in dB and r ₀ = 10 × d. In order to obtain a reduction effect by cancellation of about 10 dB, for example, Φ may be suppressed to about 25 degrees and Δ may be suppressed to about 20%. Alternatively, Φ may be suppressed to about 15 degrees and Δ may be suppressed to about 30%.

FIG. 5 is a diagram plotted with respect to Φ and Δ when r ₀ = 30 × d. In this case, in order to obtain a reduction effect by cancellation of about 10 dB, Φ should be suppressed to 25 degrees and Δ should be suppressed to about 40%.

  As described above, the ranges of Φ and Δ that can be regarded as having approximately opposite phases and approximately the same amplitude depend on the target cancellation effect and the position of the observation point. In the present specification, the approximate opposite phase and approximately the same amplitude are considered as a range in which a desired canceling effect can be obtained at a target observation point. For example, when the observation point is a distance of 30 times or more of the distance between the centers of the coils, in order to obtain an attenuation effect of about 10 dB at a point equidistant from the two coils, the phase difference is about 180 ° to ± 25 °. And the difference in magnetic field magnitude is in the range of about ± 40%. When targeting closer observation points or obtaining a greater reduction effect, these may be set to a narrower range.

  It is possible to generate magnetic fields having substantially opposite phases from the coil 291 and the coil 292 by appropriately selecting the directions of currents flowing through the two coils. For example, it is possible to generate a magnetic field having an approximately opposite phase by turning the windings of two coils in reverse and driving them with a voltage of the same phase. Similarly, a substantially reversed phase magnetic field can be generated by driving the windings in the same direction and driving them with voltages of opposite phases.

  It is possible to generate magnetic fields of approximately the same magnitude from the coil 291 and the coil 292 by adjusting the current values of the two coils. When two coils having substantially the same inductance are used, magnetic fields having approximately the same magnitude can be generated by making the current amplitudes approximately the same.

  Since the magnitude of the magnetic field generated by the coil is proportional to the inductance, when using coils having different inductances, the ratio of the current amplitude of each coil is adjusted according to the ratio of the inductances so that they are approximately the same. A magnetic field having a magnitude can be generated. That is, when coils having different inductances are used, even if the power transmission coil unit is driven using the same AC power supply amplitude, the generated magnetic fields are not substantially the same. Even if the inductance is the same, if the positional relationship between the coil 291 and the coil 391 and the coil 292 and the coil 392 are different, or if there is manufacturing variation in the coil, drive with an AC power supply of the same amplitude. However, it is conceivable that the current amplitudes are not substantially the same. Even in such a case, it is possible to generate magnetic fields having substantially the same magnitude by adjusting the current amplitude of each coil.

Hereinafter, a method for adjusting the current to generate magnetic fields having substantially the same magnitude will be described.
As described above, in order to generate a magnetic field of approximately the same magnitude from each coil, the magnitude of the current value of each coil may be adjusted. When two coils having the same inductance are used, the current amplitude may be adjusted to be the same, and this case will be described below.

  The transmission current amplitude control unit 52 compares the outputs of the current amplitude detection units 511 and 512 and generates the conversion ratio adjustment signals 1 and 2 according to the comparison result (the voltage conversion ratio of the DC-DC converters 331 and 332 is set). adjust. For example, the voltage of the DC-DC converters 331 and 332 is set so that the difference between the outputs of the current amplitude detectors 511 and 512 is 0 or close to 0, or the ratio of the outputs is 1 or close to 1. Adjust the conversion ratio. Alternatively, the voltage conversion ratios of the DC-DC converters 331 and 332 are adjusted so that the difference or ratio between the outputs of the current amplitude detectors 511 and 512 falls within a predetermined range.

  The fact that the coil current can be adjusted by changing the voltage conversion ratio of the DC-DC converter will be described. For the sake of explanation, as shown in FIG. 6, a wireless power transmission apparatus including only one system is considered. The wireless power transmission device in FIG. 6 includes a power transmission unit and a power reception unit. The power transmission unit includes an AC power supply 21 and one power transmission coil unit 220. The power transmission coil unit 220 includes a coil 290 and a capacitor 280 connected in series. The power receiving unit includes one power receiving coil unit 310, a rectifier 320, a DC-DC converter 330, and a load 34. The power receiving coil unit 310 includes a coil 390 and a capacitor 380 connected in series.

  FIG. 7 is a graph showing an example of the calculation result of the relationship between the voltage conversion ratio of the DC-DC converter 330 in FIG. 6 and the power transmission coil current. As can be understood from FIG. 7, the transmission current can be increased or decreased by changing the voltage conversion ratio of the DC-DC converter. This relationship depends on the inductance of the coils 290 and 390, the coupling coefficient between the coils 290 and 390, and the like, but when the resonance frequency of the power transmission and reception coil units 220 and 310 and the power transmission frequency are approximately the same. Shows a similar trend. In the case of the configuration shown in FIG. 6, increasing the voltage conversion ratio as shown in FIG. 7 monotonically decreases the transmission coil current, and decreasing the voltage conversion ratio monotonously increases the transmission coil current. Become.

  In addition, the increase / decrease relationship as shown in FIG. 7 may change according to the structure of the power transmission side or the power receiving side. For example, consider a case where a filter circuit serving as an impedance inverter as shown in FIG. 8 is connected to the input side of the coil unit on the power transmission side or the output of the coil unit on the power reception side in FIG. In the filter circuit of FIG. 8, coils 801 and 802 are connected in series, and a capacitor 803 is connected between a connection node between the coils and the ground. In this configuration, the increase / decrease relationship between the voltage conversion ratio and the transmission coil current can be opposite to the increase / decrease relationship of FIG. That is, when the voltage conversion ratio of the DC-DC converter is increased, the transmission current is increased, and when it is decreased, the transmission current is decreased. Thus, the relationship between the voltage conversion ratio of the DC-DC converter and the transmission current can vary depending on the device configuration. The present embodiment is applicable to both cases where the transmission current monotonously increases and monotonously decreases with increasing voltage conversion ratio. Hereinafter, as shown in FIG. 7, the case where the current monotonously decreases as the voltage conversion ratio increases will be described. However, when the increase / decrease relationship is reversed, the description regarding the voltage conversion ratio and the current increases. The same method can be applied by replacing the decrease with the increase and the decrease with the increase.

  As described above, the coil 291 is mainly coupled with the coil 391, and the coupling with other coils is relatively weak. Further, the coil 292 is mainly coupled to the coil 392, and the coupling with other coils is relatively weak. At this time, when approximation is performed considering only the main coupling, system 1 (system including power transmission coil unit 221 and power reception coil unit 311, rectifier 321, DC-DC converter 331) and system 2 (power transmission coil unit 222 and power reception) It can be considered that two systems including a coil unit 312, a rectifier 322, and a DC-DC converter 332) are connected in parallel. That is, approximately, the response of each system is substantially the same as the response in the single system configuration shown in FIG. Therefore, by changing the voltage conversion ratio of the DC-DC converter 331 in FIG. 1, the current of the coil 291 is changed with the same characteristics as in FIG. At this time, the current of the coil 292 is affected by the change in the voltage conversion ratio of the DC-DC converter 331 due to the coupling between the coil 292 and the coil 391, but the coupling between the coil 292 and the coil 391 is And weaker than the main coupling between the coils 391. For this reason, the current change due to the change of the voltage conversion ratio of the DC-DC converter 331 is greater in the coil 291 than in the coil 292. That is, the current of the coil 291 can be increased or decreased relative to the current of the coil 292 by changing the voltage conversion ratio of the DC-DC converter 331. Similarly, the current of the coil 292 can be increased or decreased relative to the current of the coil 291 by changing the voltage conversion ratio of the DC-DC converter 332.

  Therefore, in order to make the current amplitudes of the coil 291 and the coil 292 match or approach each other, the following adjustment may be performed. When the current of the coil 291 is larger than the current of the coil 292, the voltage conversion ratio of the DC-DC converter 331 is increased so that the current of the coil 291 decreases. Alternatively, the voltage conversion ratio of the DC-DC converter 332 is decreased so that the current of the coil 292 increases. When the current of the coil 291 is smaller than the current of the coil 292, the voltage conversion ratio of the DC-DC converter 331 is decreased so that the current of the coil 291 increases. Alternatively, the voltage conversion ratio of the DC-DC converter 332 is increased so that the current of the coil 292 decreases. By repeating this, the currents of the coil 291 and the coil 292 can be brought close to each other.

  In FIG. 1, the transmission current amplitude control unit 52 is configured to adjust the voltage conversion ratios of both the DC-DC converters 331 and 332, but may be configured to adjust only one of them. When adjusting both voltage conversion ratios, the required change range of the voltage conversion ratio can be made smaller than when only one of them is adjusted.

  As a changing method when changing both the DC-DC converters 331 and 332, the voltage conversion ratios of the DC-DC converters 331 and 332 may be alternately changed in a time division manner. Alternatively, when the voltage conversion ratio of the DC-DC converter 331 is increased, the voltage conversion ratio of the DC-DC converter 332 may be decreased by an equal amount at the same time. When the voltage conversion ratio of the DC-DC converter 331 is decreased, the voltage conversion ratio of the DC-DC converter 332 may be increased by an equal amount at the same time. Thereby, it is expected that the influence of the change of the voltage conversion ratio of the converter 331 on the system 1 and the influence of the change of the voltage conversion ratio of the converter 332 on the system 2 are almost the same amount and in the opposite directions. The In other words, the effect of the change is reduced when the entire system is viewed. This means that the amount of power transmitted before and after the change of the voltage conversion ratio is substantially constant.

  FIG. 9 shows an example of an operation flow of the transmission current amplitude control unit 52. First, the outputs of the current amplitude detectors 511 and 512 are acquired (S101). The output of the current amplitude detector 511 is compared with the output of the current amplitude detector 512 (S102). If the output of the current amplitude detector 511 is larger than the output of the current amplitude detector 512 (YES), the voltage conversion ratio of the DC-DC converter 331 is increased (S103). If the output of the current amplitude detector 511 is smaller than the output of the current amplitude detector 512 (NO), the voltage conversion ratio of the DC-DC converter 331 is decreased (S104). If they match, nothing is done and the current voltage conversion ratio may be maintained. Thereby, the outputs of the two current amplitude detectors can be brought close to each other. The operation of the flow of FIG. 9 may be executed at regular time intervals, or may be configured to be executed a predetermined number of times when a fluctuation factor of the coil current occurs. As an example of the variation factor, for example, a case where a variation in the position or orientation of the coil on the power transmission side or the power reception side is detected can be considered.

  In the operation of the flow of FIG. 9, the voltage conversion ratio of the DC-DC converter 331 is adjusted. As described above, instead of the voltage conversion ratio of the DC-DC converter 331, the voltage of the DC-DC converter 332 is adjusted. The conversion ratio may be adjusted. Alternatively, both the voltage conversion ratio of the DC-DC converter 331 and the voltage conversion ratio of the DC-DC converter 332 may be adjusted.

  In addition, when coils having different inductances are used as the coils 291 and 292, the output ratios of the current amplitude detection unit 511 and the current amplitude detection unit 512 are not compared with each other but are compared with a predetermined value. Depending on the relationship, the voltage conversion ratio of one or both of the DC-DC converters 331 and 332 may be adjusted.

  FIG. 10 shows another example of the operation flow of the transmission current amplitude control unit 52. As a difference from FIG. 9, step S201 is added before step S102. In step S201, it is determined whether the ratio between the output of the current amplitude detector 511 and the output of the current amplitude detector 512 is outside a predetermined range. If it is within the predetermined range (NO), it is determined that current adjustment is unnecessary (determined that substantially the same magnetic field is generated from the coils 291 and 292). If it is outside the predetermined range (YES), the process proceeds to step S102, and the same processing as in step S102 and subsequent steps in FIG. 9 is performed.

  If the coils 291 and 292 have the same inductance, etc., and if the currents of the coils are controlled to be substantially the same, it is determined in step S201 whether the absolute value of the output difference, not the ratio, is within a predetermined range. May be determined. In this case, if the absolute value of the output difference is within a predetermined range, the current is not adjusted, and if it is outside the predetermined range, the process proceeds to step S102. Thereafter, the same processing as step S102 in FIG. 9 is performed.

  FIG. 11 shows another configuration example of the power transmission coil unit. Here, although the example of a change of the power transmission coil unit 2 is shown, the power transmission coil unit 1 can be changed similarly. FIG. 11A shows a configuration in which the connection of the coil 292 and the capacitor 282 is replaced with the configuration of FIG. FIG. 11B shows a configuration in which capacitive elements 282a and 282b are connected to both sides of the coil 292, respectively. FIG. 11C shows a configuration in which two coils 292a and 292b are connected in series, and a capacitor 282a is connected to the opposite side of the coil 292a to the coil 292b. The configuration of the power receiving coil units 1 and 2 can be changed in the same manner as in FIGS. 11A to 11C. In addition, each coil unit for power transmission and power reception can have any configuration as long as it operates as a series resonance circuit. Note that the coil may be a winding itself, or a coil in which a winding is wound around a magnetic core.

  FIG. 12 shows a modification of the wireless power transmission apparatus of FIG. The control device is not shown. In the configuration of FIG. 1, one AC power source is commonly connected to each power transmission coil unit. Further, one load is commonly connected to each DC-DC converter. On the other hand, in the configuration of FIG. 12, two AC power supplies are used and are connected to separate power transmission coil units. Further, two loads are used and are connected to separate DC-DC converters. Note that only one of the AC power supply and the load may be used, and the other may be configured using one as in FIG.

  FIG. 13 shows a specific example of the AC power supply 21. Here, a configuration of a portion that generates AC power supplied to the power transmission coil unit 221 using the DC power source 310 and the inverter 120 is shown. The configuration of the part that generates AC power supplied to the power transmission coil unit 222 can also be configured by connecting an inverter having the same configuration as the inverter 120 to the DC power source 310. Or when using separate AC power supply for every power transmission coil unit like FIG. 12, what is necessary is just to provide separately the structure similar to FIG.

  In FIG. 13, an inverter 120 is an inverter that operates as a DC-AC converter, and includes switching elements 1201, 1202, 1203, and 1204, and diodes (freewheeling diodes) 1201 a connected in reverse parallel to these switching elements 1201 to 1204. 1202a, 1203a, 1204a. The connection in antiparallel means that the direction of current flow in each connected element is reversed (direction in which current flows backward to the DC power source). One ends of the switching elements 1201 and 1202 are connected to each other, and one ends of the switching elements 1203 and 1204 are connected to each other. The other ends of the switching elements 1201 and 1203 are commonly connected to the power supply terminal of the DC power supply 310, whereby a DC power supply voltage is supplied from the DC power supply 310. The other ends of the switching elements 1202 and 1204 are connected in common to the ground terminal of the DC power supply 310, whereby a ground voltage is supplied from the DC power supply 310. A capacitor 1211 is connected between both terminals of the DC power source 310. A connection node 1212 between the switching elements 1201 and 1202 is connected to one end of the capacitor 281 of the power transmission coil unit 221 and the current amplitude detector 511. A connection node 1213 between the switching elements 1203 and 1204 is connected to one end of the coil 291 of the power transmission coil unit 221. The inverter 120 drives each switching element based on the DC power supply voltage and the ground voltage supplied from the DC power supply 310 in accordance with a switching signal supplied from a driving device (not shown), thereby generating a voltage that is inverted between positive and negative. To generate an AC voltage. Current amplitude detector 511 detects the amplitude of the current output from connection node 1212 of inverter 120.

  When two AC power supplies are used as shown in FIG. 12, instead of measuring the output current amplitude (AC current amplitude) of the inverter, a DC current amplitude detector 1401 is connected as shown in FIG. A DC current input from the DC power source 310 to the inverter may be measured. Generally, since there is a strong correlation between the DC input current of the inverter and the output AC current of the inverter, the AC current of the power transmission coil unit can be accurately grasped by measuring the DC input current. Hereinafter, the correlation between the DC input current and the output AC current of the inverter will be described in detail.

Generally, it is known that the power factor of the inverter output is close to 1 when the resonance frequency of the coil unit on the power transmission side and the power reception side is sufficiently close to the power transmission frequency. In addition, since the resonance configuration of the coil unit on the power transmission and reception side functions as a filter, only the fundamental wave component is involved in the power transmission. In this case, when the efficiency of the inverter is 100% and the output voltage waveform of the inverter is a rectangular wave with a duty of 50%, the fundamental wave component I _AC of the output AC current of the inverter and the input DC current to the inverter between the I _DC, such as the following relationship is established.

  That is, since information on the amplitude of the alternating current can be grasped by observing the DC current, the amplitude of the DC current may be detected as shown in FIG. 14 instead of detecting the amplitude of the alternating current. By setting it as such a structure, measurement of an electric current becomes easy rather than measuring an alternating current.

  FIG. 15 shows a specific example of the rectifier 321 of FIG. In FIG. 15, a full-bridge connected diode rectifier is shown. Other types of rectifiers may be used. In FIG. 15, diodes 1501 and 1502 are connected in series, and diodes 1503 and 1504 are connected in series. A connection node 1505 of the diodes 1501 and 1502 is connected to one end of the coil 391 of the power receiving coil unit 1, and a connection node 1506 of the diodes 1503 and 1504 is connected to one end of the capacitor 381 of the power receiving coil unit 1. The terminals on the opposite side of the connection nodes 1505 and 1506 of the diode 1501 and the diode 1503 are connected to one of the two input terminals of the DC-DC converter 331, and the connection node 1505 of each of the diode 1502 and the diode 1504. , 1506 is connected to the other input terminal of the DC-DC converter 331. Although a specific example of the rectifier 321 is shown in FIG. 15, the rectifier 322 can be configured similarly.

  Hereinafter, some specific examples of the DC-DC converter will be described. Any configuration described below can be implemented as the DC-DC converters 331 and 332. The relationship between the transmission current and the DC-DC conversion ratio shown in FIG. 7 does not depend on the method for realizing the DC-DC converter. Therefore, any configuration other than that described below may be used as the configuration of the DC-DC converter.

  FIG. 16 shows an example of a buck converter as a first configuration example of the DC-DC converter. Switching element M1 and diode 1601 are connected in series. A diode 1602 is connected in antiparallel to the switching element M1. A connection node 1603 between the switching element M1 and the diode 1601 is connected to the output terminal 1611 via the coil 1604. A terminal of the switching element M1 opposite to the diode 1601 is connected to one of the two output terminals of the rectifier. A terminal of the diode 1601 opposite to the switching element M1 is connected to the other of the two output terminals of the rectifier and is connected to the output terminal 1612. A smoothing capacitor 1613 is connected between the output terminals 1611 and 1612. The output terminals 1611 and 1612 are connected to a load. In the configuration of FIG. 16, the voltage conversion ratio is controlled by controlling the duty ratio of the pulse waveform applied to the switching element M1 from the drive device (not shown). In this configuration, ideally, the voltage conversion ratio can be set to an arbitrary value of 1 or less.

  FIG. 17 shows an example of a boost converter as a second configuration example of the DC-DC converter. Switching element M2 and diode 1701 are connected in series. A diode 1702 is connected in antiparallel to the switching element M1. A connection node 1703 between the switching element M1 and the diode 1701 is connected to one of the two output terminals of the rectifier via the coil 1704. A terminal of the diode 1701 opposite to the switching element M1 is connected to the output terminal 1711. A terminal of the switching element M1 opposite to the diode 1701 is connected to the other of the two output terminals of the rectifier and to the output terminal 1712. A smoothing capacitor 1713 is connected between the output terminals 1711 and 1712. The output terminals 1711 and 1712 are connected to a load. In the configuration of FIG. 17, the voltage conversion ratio is controlled by controlling the duty ratio of the pulse waveform applied to the switching element M2 from the driving device (not shown). In this configuration, ideally, the voltage conversion ratio can be set to an arbitrary value of 1 or more.

  FIG. 18 shows an example of a buck-boost converter as a third configuration example of the DC-DC converter. Switching element M3 and coil 1801 are connected in series. A diode 1802 is connected in antiparallel to the switching element M3. A connection node 1803 between the switching element M3 and the coil 1801 is connected to the output terminal 1811 via a diode 1804 in the reverse direction. That is, the connection node 1803 is connected to the cathode of the diode 1804, and the anode of the diode 1804 is connected to the output terminal 1811. A terminal of the switching element M3 opposite to the coil 1801 is connected to one of the two output terminals of the rectifier. A terminal of the coil 1801 opposite to the switching element M3 is connected to the other of the two output terminals of the rectifier and is connected to the output terminal 1812. A smoothing capacitor 1813 is connected between the output terminals 1811 and 1812. The output terminals 1811 and 1812 are connected to a load. In the configuration of FIG. 18, the voltage conversion ratio is controlled by controlling the duty ratio of the pulse waveform applied from the driving device (not shown) to the switching element M3. In this configuration, ideally, the voltage conversion ratio can be set to an arbitrary value. However, the input / output polarity is reversed.

  FIG. 19 shows an example of a non-inverting buck-boost converter as a fourth configuration example of the DC-DC converter. Switching element M4 and diode 1901 are connected in series. A diode 1902 is connected in antiparallel to the switching element M4. A connection node 1903 between the switching element M4 and the diode 1901 is connected to one end of the coil 1904. The terminal of the switching element M4 opposite to the diode 1901 is connected to one of the two output terminals of the rectifier. A terminal of the diode 1901 opposite to the switching element M4 is connected to the other of the two output terminals of the rectifier and is connected to the output terminal 1912. Further, the switching element M5 and the diode 1921 are connected in series. A diode 1922 is connected in antiparallel to the switching element M5. A connection node 1923 between the switching element M5 and the diode 1921 is connected to the other end of the coil 1904. A terminal of the diode 1921 opposite to the switching element M5 is connected to the output terminal 1911. The terminal of the switching element M5 opposite to the diode 1921 is connected to the other of the two output terminals of the rectifier and is connected to the output terminal 1912. A smoothing capacitor 1913 is connected between the output terminals 1911 and 1912. The output terminals 1911 and 1912 are connected to a load. In the configuration of FIG. 19, the voltage conversion ratio is controlled by controlling the duty ratio of the pulse waveform applied to the switching elements M4 and M5 from the driving device (not shown). In this configuration, ideally, the voltage conversion ratio can be set to an arbitrary value.

  As other examples of the DC-DC converter, a SEPIC (Single Ended Primary Inductor Converter), a Cuk converter, or the like may be used. In addition, any other configuration such as an insulated one-stone forward converter, a two-stone forward converter, an insulated buck converter, and a flyback converter can be selected. In any of the configuration examples of the DC-DC converter described here, the voltage conversion ratio can be controlled by changing the duty ratio of the pulse waveform applied to the switching device. In the practice of the present invention, any configuration can be used as long as the DC-DC converter can control the voltage conversion ratio with the duty ratio of the pulse waveform.

  FIG. 20 shows a modification of the wireless power transmission apparatus shown in FIG. In FIG. 1, the transmission current amplitude control unit 52 is connected to the DC-DC converters 331 and 332 by a wire such as a communication cable and transmits the conversion ratio adjustment signals 1 and 2, but in FIG. The structure which transmits the conversion ratio adjustment signals 1 and 2 is shown. A wireless unit 2001 is disposed in the control device or the power transmission unit 20, and a wireless unit 2002 is disposed in the power receiving unit. The wireless unit 2001 and the wireless unit 2002 perform communication using a predetermined method. A general wireless communication standard such as a wireless LAN or Bluetooth (registered trademark) may be used, or an original wireless communication standard may be used. Note that the wireless unit 2001 and the wireless unit 2002 are each provided with a communication antenna. The wireless unit 2001 receives the conversion ratio adjustment signals 1 and 2 from the transmission current amplitude control unit 52 and transmits the signals to the wireless unit 2001 wirelessly. Radio section 2002 receives conversion ratio adjustment signals 1 and 2 from radio section 2001 and outputs them to DC-DC converters 331 and 332, respectively. With the configuration of FIG. 20, it is not necessary to connect the power transmission side and the power reception side with a wire, so convenience is improved. In addition, when used in the vicinity of a passage where people are coming and going, people will not trip over the cable, so safety will be improved.

  FIG. 21 shows another modification of the wireless power transmission apparatus shown in FIG. In the modification of FIG. 20, the transmission current amplitude control unit 52 is disposed on the power transmission side, but in the present modification, it is disposed on the reception side. Similarly to FIG. 20, radio units 2001 and 2002 are arranged on the power transmission side and the power reception side, respectively. The wireless unit 2001 receives the signal of the current amplitude value output from the current amplitude detection units 511 and 512, and transmits the signal wirelessly. The wireless unit 2002 receives the signal transmitted from the wireless unit 2001, acquires the current amplitude value of the current amplitude detection units 511 and 512, and outputs the current amplitude value to the power transmission current amplitude control unit 52. The transmission current amplitude control unit 52 generates the conversion ratio adjustment signals 1 and 2 based on these current amplitude values, and outputs them to the DC-DC converters 331 and 332, respectively. According to the configuration in FIG. 21, the same effect as the configuration in FIG. 20 can be obtained, and the configuration on the power transmission side can be simplified.

  As described above, according to the present embodiment, each power transmission coil unit is controlled by controlling the voltage conversion ratio of the DC-DC converter on the power receiving side based on the detected value of the amplitude of the power transmission current of the plurality of power transmission coil units. The transmission current amplitude can be controlled to a desired relationship, and thus radiation emission at the observation point can be reduced.

(Second Embodiment)
In FIG. 22, the block diagram of the wireless power transmission apparatus which concerns on the 2nd Embodiment of this invention is shown. As a difference from the first embodiment, a current phase detection unit 611, a current phase detection unit 612, and a current phase control unit (third control unit) 62 are added. Further, as in the modification of the first embodiment shown in FIG. 12, an AC power source is arranged for each system. That is, an AC power supply 211 is arranged for the system 1 and an AC power supply 212 is arranged for the system 2.

  The current phase detection unit 611 detects the phase of the input current of the power transmission coil unit 1. The current phase detector 612 detects the phase of the input current of the power transmission coil unit 2. The current phase control unit 62 adjusts the phase of the output voltage of at least one of the AC power supply 211 and the AC power supply 212 so that the phase difference detected by the current phase detection units 611 and 612 approaches approximately 180 degrees. By changing the phase of the AC power supplies 211 and 212, the current phase of the power transmission coil units 1 and 2 connected to the AC power supplies 211 and 212 can be changed. Therefore, the current phase difference between the power transmission coil units 1 and 2 can thereby be adjusted to approximately 180 degrees.

  That is, in the first embodiment, when the resonance frequency of the power transmission coil unit 1 and the power transmission coil unit 2 is slightly different, when the resonance frequency of the power reception coil unit 1 and the power reception coil unit 2 is slightly different, or If the resonance frequency of each power transmission coil unit and power reception unit is slightly different, even if the phase relationship of the current to each power transmission coil unit is adjusted to approximately 180 degrees with an AC power source, The phase difference may not be approximately 180 degrees. On the other hand, in 2nd Embodiment, the phase of the electric current of each power transmission coil unit is detected, and each power transmission coil unit is controlled by controlling the phase of at least one of AC power supplies 211 and 212 according to these differences. Can be adjusted to approximately 180 degrees.

  As a specific operation example of the current phase control unit 62, a condition that the phase difference is approximately 180 degrees may be searched while sequentially shifting at least one of the phases of the AC power supplies 211 and 212. Further, a feedback circuit using a phase comparator may be employed as generally used in a phase locked loop.

  Also in the second embodiment, similarly to the first embodiment, wireless units are arranged on the power transmission side and the power reception side, and the conversion ratio adjustment signals 1 and 2 are wirelessly transmitted to the DC-DC converters 321 and 322, respectively. You may notify via communication.

  As described above, according to the present embodiment, the voltage of the AC power supplies 211 and 212 is detected by detecting the phase of the current of each power transmission coil unit and controlling the phase of at least one of the AC power supplies 211 and 212 according to the difference therebetween. Even when the phase difference between the currents of the power transmission coil units does not become approximately 180 degrees when the phase difference is approximately 180 degrees, the phase difference between the currents of the power transmission coil units can be adjusted to approximately 180 degrees.

(Third embodiment)
FIG. 23 shows a configuration diagram of a wireless power transmission device according to the third embodiment. As a difference from the first embodiment, a current amplitude detector 711, a current phase detector 712, and a received current amplitude controller (second controller) 72 are added on the power receiving side. Moreover, the alternating current power supply is arrange | positioned for every system | strain like the modification of 1st Embodiment shown in FIG. That is, an AC power supply 211 is arranged for the system 1 and an AC power supply 212 is arranged for the system 2.

  The current amplitude detector 711 detects the amplitude of the output current of the power receiving coil unit 1. The current phase detector 712 detects the amplitude of the output current of the power receiving coil unit 2. The received current amplitude control unit 72 generates at least one of the AC power supply amplitude adjustment signals 1 and 2 so that the amplitudes detected by the current phase detection units 611 and 612 match or approximately match. The current amplitude detection unit 711 is connected to the AC power supplies 211 and 212, and outputs the generated AC power supply amplitude adjustment signals 1 and 2 to the AC power supplies 211 and 212. As a result, the amplitude of at least one of the AC power supply 212 is adjusted. The AC power supplies 211 and 212 adjust the amplitude of the AC current according to the input AC power supply amplitude adjustment signals 1 and 2. By doing in this way, the magnetic field generated from the coil on the power receiving side can be made to have a substantially opposite phase and substantially the same amplitude, and thus radiation emission due to the magnetic field generated from the coil on the power receiving side can be reduced.

  That is, since the coil on the power receiving side also generates a magnetic field, it can be a source of radiation emission. When it becomes a generation source of radiated emissions, it is desirable to cancel out by setting the magnetic fields generated from the two coils on the power receiving side to have approximately opposite phases and approximately the same amplitude as in the power transmission side. When the resonance frequency of each power transmission coil unit and the power reception coil unit and the power transmission frequency are approximately the same, the phase difference of the current between the coils on the power transmission side and the phase difference of the current between the coils on the power reception side are: Since they are substantially the same, if the current phase difference between the coils 291 and 292 on the power transmission side is approximately opposite in phase, it is expected that the currents in the coils 391 and 392 on the power reception side also have approximately opposite phases. Therefore, radiated emissions corresponding to the magnetic field generated from the coil on the power receiving side is reduced by controlling the current amplitude of the coil on the power receiving side to be substantially the same while making the phase of each AC power supply approximately opposite in phase. it can. Hereinafter, the reason why the current amplitudes of the coil 391 and the coil 392 on the power receiving side can be adjusted to be substantially the same by adjusting the voltage amplitudes of the AC power sources 211 and 212 will be described in detail.

  FIG. 24 shows an example of a graph of the calculation result of the relationship between the voltage amplitude of the AC power supply and the coil current on the power receiving side in the one-system wireless power transmission device shown in FIG. By increasing the voltage amplitude, the coil current on the power receiving side monotonously increases, and by reducing the voltage amplitude, the coil current on the power receiving side monotonously decreases. Thus, in the case of a single-system wireless power transmission device, the received current can be increased or decreased by changing the voltage amplitude of the AC power supply. The graph of FIG. 24 depends on the inductance of each coil, the coupling coefficient between each coil, etc., but when the resonance frequency of each power transmission coil unit and power reception coil unit and the power transmission frequency are approximately the same, A similar trend is shown.

  Similar to the first embodiment, it can be considered that the wireless power transmission device according to the present embodiment has two systems connected in parallel. That is, as described above, the coil 391 on the power receiving side is mainly coupled to the coil 291 on the power transmission side, and the coupling with other coils is relatively weak. In addition, the coil 392 on the power receiving side is mainly coupled to the coil 292 on the power transmission side, and the coupling with other coils is relatively weak. At this time, when approximation is performed considering only the main coupling, system 1 (path including power transmission coil unit 221 and power reception coil unit 311, rectifier 321, DC-DC converter 331) and system 2 (power transmission coil unit 222 and power reception) It can be considered that the two systems of the coil unit 312, the rectifier 322, and the path including the DC-DC converter 332) are connected in parallel. That is, approximately, the response of each system is almost the same as the response in the configuration of one system shown in FIG.

  At this time, by changing the amplitude of the AC power supply 211 for the system 1, the current of the coil 391 is changed with the same characteristics as in FIG. At this time, the current of the coil 392 in the system 2 is affected by the change in the output amplitude of the AC power supply 211 due to the coupling between the coil 291 and the coil 392, but the coupling between the coil 291 and the coil 392 is the same as that of the coil 291 and the coil 391. Weak compared to the main bond between. For this reason, the current change due to the change in the output amplitude of the AC power supply 211 is greater in the coil 391 than in the coil 392. That is, by changing the amplitude of the AC power supply 211, the current of the coil 391 can be increased or decreased relative to the current of the coil 392. Similarly, by changing the amplitude of the AC power supply 212, the current of the coil 392 can be increased or decreased relative to the current of the coil 391.

  As an example of the operation of the received current amplitude control unit 72, the currents of the coil 391 and the coil 392 may be adjusted as follows in order to match or approximately match. When the current of the coil 391 is larger than the current of the coil 392, the output amplitude of the AC power supply 211 is decreased so that the current of the coil 391 is decreased. Alternatively, the output amplitude of the AC power supply 212 is increased so that the current of the coil 392 increases. On the other hand, when the current of the coil 391 is smaller than the current of the coil 392, the output amplitude of the AC power supply 211 is increased so that the current of the coil 391 increases. Alternatively, the output amplitude of the AC amplitude 212 is decreased so that the current of the coil 392 is decreased. By repeating this, the currents of the coil 391 and the coil 392 can be brought close to each other.

  As the method for adjusting the amplitude of the AC power supply, the same method as the various operation flows of the voltage conversion ratio in the first embodiment can be applied to the second embodiment.

  Here, the operation of the power transmission current amplitude control unit 52 (current amplitude adjustment of the power transmission coil units 1 and 2) and the operation of the power reception current amplitude control unit 72 (current amplitude adjustment of the power reception coil units 1 and 2) are performed simultaneously (in parallel). May be performed), or may be controlled not to be performed simultaneously. In the latter case, the current amplitude adjustment of the power transmission coil units 1 and 2 and the current amplitude adjustment of the power reception coil units 1 and 2 may be performed at time intervals or while switching alternately. With such a configuration, only one adjustment on the power transmission side and the power reception side is always selected, and interference between the two adjustments can be reduced and stability can be improved.

  This embodiment is particularly suitable when a battery is used as a load. This will be described in detail below.

  FIG. 25 is a graph G11 showing the relationship between the current of the power transmission coil unit and the voltage amplitude of the AC power source when a battery is connected as a load in the one-system wireless power transmission device shown in FIG. The graph G12 of the relationship between the electric current of a unit and the voltage amplitude of AC power supply is shown. FIG. 26 is a graph G21 of the relationship between the current of the power transmission coil unit and the voltage conversion ratio of the DC-DC converter in the same case, and the relationship between the current of the power reception coil unit and the voltage conversion ratio of the DC-DC converter. The graph G22 is shown.

  As can be seen by comparing the graphs G11 and G12 in FIG. 25, the current change in the power transmission coil unit is sufficiently smaller than the current change in the power reception coil unit. Moreover, as can be seen by comparing the graphs G21 and G22 in FIG. 26, the current change in the power receiving coil unit is sufficiently smaller than the current change in the power transmission coil unit.

  That is, when the voltage conversion ratio of the DC-DC converter is changed to control the transmission current, the influence on the reception current is sufficiently small, and when the voltage amplitude of the AC power supply is changed to control the reception current. The effect on transmission current is small enough. Therefore, it can be said that the two controls do not easily interfere with each other.

  In the configuration shown in FIG. 23, the amplitude of the alternating current that is the output of the power receiving coil units 1 and 2 is measured, but instead, the amplitude of the DC current that is the output of the rectifiers 321 and 322 may be measured. A configuration example in which the current amplitude detection unit of the DC current is connected to the subsequent stage of the rectifier 321 is shown in FIG. A current amplitude detector 2701 for DC current is connected to the subsequent stage of a diode rectifier having a full bridge connection similar to that shown in FIG. A smoothing capacitor 2702 is connected to the output side of the full bridge connection. It is possible to control the voltage amplitude of the AC power supply using the amplitude of the DC current instead of the amplitude of the AC current. Hereinafter, this reason will be described. FIG. 23 shows an example in which a DC current amplitude detector is connected to the subsequent stage of the rectifier 321, but the rectifier 322 may be connected in the same manner.

When the efficiency of the rectifier is 100%, the rectifier input current is sinusoidal, and a resistive load is connected to the rectifier output, the fundamental wave component I _AC and the output DC current I _DC of the input AC current of the ideal rectifier The following relationship holds between the two.

  That is, since the information about the amplitude of the alternating current can be grasped by observing the DC current, the DC current is measured by the DC current amplitude detecting unit as shown in FIG. 27, and the voltage amplitude of the alternating current power source is adjusted using this. Can do. By setting it as such a structure, measurement of an electric current becomes easy rather than measuring an alternating current.

  In the third embodiment, similarly to the first embodiment, wireless units are arranged on the power transmission side and the power reception side, and the conversion ratio adjustment signals 1 and 2 are transmitted to the DC-DC converters 321 and 322 via wireless communication. May be notified (see FIGS. 20 and 21). In addition, the AC power supply amplitude adjustment signals 1 and 2 may be notified to the AC power supplies 211 and 212 via wireless communication using wireless units arranged on the power transmission side and the power reception side.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

20: Power transmission unit 30: Power reception unit 21: AC power source 221 1: Power transmission coil unit 1
222: Power transmission coil unit 2
281, 282, 803, 1211, 1613, 1713, 1813, 1913: Capacitance 291, 292, 391, 392, 1604, 1704, 1801, 1904, 801, 802, 282a, 282b, 292a, 292b: Coil 311: Power receiving coil Unit 1
321, 322: Rectifier 331, 332: DC-DC converter 312: Power receiving coil unit 2
34: Loads 381, 382, 1211: Capacities 511, 711, 512, 712, 2701: Current amplitude detection unit 52: Transmission power amplitude control unit 72: Receiving current amplitude control unit 310: DC power supplies 1201-1204, M1-M4: Switching elements 1201a to 1204a, 1501-1504, 1601, 1602, 1701, 1702, 1802, 1804, 1901, 1902, 1912, 1922: Diodes 1611, 1711, 1811, 1911, 1612, 1712, 1812, 1912: Output terminal 2001 2002: Radio unit 611: Current phase detection unit 612: Current phase detection unit 62: Current phase control unit

Claims (20)

A first power transmission coil unit including a first power transmission coil and a capacity connected in series to the first power transmission coil; a second power transmission coil; and a capacity connected in series to the second power transmission coil. A second power transmission coil unit including: a power transmission unit including:
A first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil; a second power receiving coil; a capacitor connected in series to the second power receiving coil; Including a second power receiving coil unit, a first rectifier that converts the power received by the first power receiving coil unit into a direct current, and a DC power voltage converted by the first rectifier. A first DC-DC converter for conversion, a second rectifier for converting electric power received by the second power receiving coil unit into direct current, and a voltage of the direct-current power converted by the second rectifier are converted to DC A second DC-DC converter that performs DC conversion;
The absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is larger than the absolute value of the coupling coefficient between the first power transmission coil and the second power reception coil,
The absolute value of the coupling coefficient between the second power transmission coil and the second power reception coil is larger than the absolute value of the coupling coefficient between the second power transmission coil and the first power reception coil.
A control device for controlling a wireless power transmission device,
Voltage conversion of the first DC-DC converter based on a first detection value relating to the current amplitude of the first power transmission coil unit and a second detection value relating to the current amplitude of the second power transmission coil unit. A control device comprising: a first control unit that controls at least one of the ratio and the voltage conversion ratio of the second DC-DC converter. Control at least one of the voltage conversion ratio of the first DC-DC converter and the voltage conversion ratio of the second DC-DC converter according to the difference or ratio between the first and second detection values. The control device according to claim 1. So that the difference is reduced, or the difference is included in a predetermined range, or the ratio is close to a predetermined value, or the ratio is included in a predetermined range. The control device according to claim 2, wherein at least one of the voltage conversion ratios of the first and second DC-DC converters is controlled. The first detection value represents an amplitude of an alternating current input to the first power transmission coil unit from an alternating current power source,
The control device according to any one of claims 1 to 3, wherein the second detection value represents an amplitude of an alternating current input to the second power transmission coil unit from the alternating current power supply or another alternating current power supply. An alternating current obtained by converting a direct current generated by the first direct current power source by the first inverter is input to the first power transmission coil unit, and a direct current generated by the second direct current power source is converted by the second inverter. The alternating current is input to the second power transmission coil unit, the first detection value represents the amplitude of the direct current input to the first inverter,
4. The control device according to claim 1, wherein the second detection value represents an amplitude of the direct current input to the second inverter. 5. The power receiving unit includes a wireless unit that performs wireless communication,
A first radio that wirelessly transmits a control signal for controlling at least one of the voltage conversion ratio of the first DC-DC converter and the voltage conversion ratio of the second DC-DC converter to the power receiving unit. The control device according to claim 1, further comprising a unit. The power transmission unit includes a wireless unit that performs wireless communication,
The control device according to claim 1, further comprising: a second wireless unit that wirelessly receives the first and second detection values from the power transmission unit. The wireless power transmission device includes a first AC power source that supplies an AC current to the first power transmission coil unit, and a second AC power source that supplies an AC current to the second power transmission coil unit,
Based on the third detection value related to the current amplitude of the first power receiving coil unit and the fourth detection value related to the current amplitude of the second power receiving coil unit, the output voltage of the first AC power supply and the second The control apparatus as described in any one of Claim 1 thru | or 7 provided with the 2nd control part which controls at least one of the output voltage of AC power supply of. The second control unit controls at least one of an output voltage of the first AC power supply unit and an output voltage of the second AC power supply unit according to a difference or ratio between the third and fourth detection values. The control device according to claim 8. The second control unit may be configured such that the difference is reduced, the difference is included in a predetermined range, the ratio approaches a predetermined value, or the ratio is in a predetermined range. The control device according to claim 9, wherein at least one of the output voltages of the first and second AC power supplies is controlled so as to be included. The third detection value represents an amplitude of an alternating current input to the first rectifier,
The control device according to any one of claims 8 to 10, wherein the fourth detection value represents an amplitude of an alternating current input to the second rectifier. The third detection value represents an amplitude of a direct current output from the first rectifier,
The control device according to any one of claims 8 to 10, wherein the fourth detection value represents an amplitude of a direct current output from the second rectifier. The power transmission unit includes a wireless unit that performs wireless communication,
The third wireless unit that wirelessly transmits a control signal for controlling at least one of an output voltage of the first AC power source and an output voltage of the second AC power source to the power transmission unit. The control device according to any one of the above. The power receiving unit includes a wireless unit that performs wireless communication,
The control device according to claim 8, further comprising a fourth wireless unit that wirelessly receives the third and fourth detection values from the power receiving unit. The control device according to any one of claims 8 to 14, wherein the first control unit and the second control unit are controlled so as not to operate simultaneously. The power transmission unit includes a first AC power source that supplies an AC current to the first power transmission coil unit, and a second AC power source that supplies an AC current to the second power transmission coil unit,
A third control unit that controls the first AC power source and the second AC power source so that phases of currents flowing through the first power transmission coil unit and the second power transmission coil unit are opposite or substantially opposite to each other; The control device according to any one of claims 1 to 15, further comprising a control unit. A first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil; a second power receiving coil; a capacitor connected in series to the second power receiving coil; Including a second power receiving coil unit, a first rectifier that converts the power received by the first power receiving coil unit into a direct current, and a DC power voltage converted by the first rectifier. A first DC-DC converter for conversion, a second rectifier for converting electric power received by the second power receiving coil unit into direct current, and a voltage of the direct-current power converted by the second rectifier are converted to DC A power transmission device that wirelessly transmits power to a power reception device including a second DC-DC converter that performs DC conversion,
A first power transmission coil unit including a first power transmission coil and a capacitor connected in series to the first power transmission coil;
A second power transmission coil unit including a second power transmission coil and a capacity connected in series to the second power transmission coil;
Voltage conversion of the first DC-DC converter based on a first detection value relating to the current amplitude of the first power transmission coil unit and a second detection value relating to the current amplitude of the second power transmission coil unit. A control unit that controls at least one of the ratio and the voltage conversion ratio of the second DC-DC converter,
The absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is based on the absolute value of the coupling coefficient between the first power transmission coil, the first power transmission coil, and the second power reception coil. Big
The absolute value of the coupling coefficient between the second power transmission coil and the second power receiving coil is greater than the absolute value of the coupling coefficient between the second power transmission coil and the first power receiving coil. A first power transmission coil unit including a first power transmission coil and a capacity connected in series to the first power transmission coil; and a second power transmission coil and a capacity connected in series to the second power transmission coil. A power receiving device that wirelessly receives power from a power transmission device including a second power transmission coil unit,
A first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil;
A second power receiving coil unit including a second power receiving coil and a capacitor connected in series to the second power receiving coil;
A first rectifier for converting electric power received by the first power receiving coil unit into direct current;
A first DC-DC converter for DC-DC converting the voltage of the DC power converted by the first rectifier;
A second rectifier that converts electric power received by the second power receiving coil unit into direct current;
A second DC-DC converter for DC-DC converting the voltage of the DC power converted by the second rectifier;
Voltage conversion of the first DC-DC converter based on a first detection value relating to the current amplitude of the first power transmission coil unit and a second detection value relating to the current amplitude of the second power transmission coil unit. And a control unit that controls at least one of the voltage conversion ratio of the second DC-DC converter, the absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is the first value. Greater than the absolute value of the coupling coefficient between one power transmission coil, the first power transmission coil, and the second power reception coil;
The absolute value of the coupling coefficient between the second power transmission coil and the second power reception coil is greater than the absolute value of the coupling coefficient between the second power transmission coil and the first power reception coil. A first power transmission coil unit including a first power transmission coil and a capacity connected in series to the first power transmission coil; a second power transmission coil; and a capacity connected in series to the second power transmission coil. A second power transmission coil unit including: a power transmission unit including:
A first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil; a second power receiving coil; a capacitor connected in series to the second power receiving coil; Including a second power receiving coil unit, a first rectifier that converts the power received by the first power receiving coil unit into a direct current, and a DC power voltage converted by the first rectifier. A first DC-DC converter for conversion, a second rectifier for converting electric power received by the second power receiving coil unit into direct current, and a voltage of the direct-current power converted by the second rectifier are converted to DC A power receiving unit including a second DC-DC converter that performs DC conversion;
Voltage conversion of the first DC-DC converter based on a first detection value relating to the current amplitude of the first power transmission coil unit and a second detection value relating to the current amplitude of the second power transmission coil unit. A controller for controlling at least one of the ratio and the voltage conversion ratio of the second DC-DC converter,
The absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is larger than the absolute value of the coupling coefficient between the first power transmission coil and the second power reception coil,
The absolute value of the coupling coefficient between the second power transmission coil and the second power reception coil is larger than the absolute value of the coupling coefficient between the second power transmission coil and the first power reception coil.
Wireless power transmission device. A first power transmission coil unit including a first power transmission coil and a capacity connected in series to the first power transmission coil; a second power transmission coil; and a capacity connected in series to the second power transmission coil. A second power transmission coil unit including: a power transmission unit including:
A first power receiving coil unit including a first power receiving coil and a capacitor connected in series to the first power receiving coil; a second power receiving coil; a capacitor connected in series to the second power receiving coil; Including a second power receiving coil unit, a first rectifier that converts the power received by the first power receiving coil unit into a direct current, and a DC power voltage converted by the first rectifier. A first DC-DC converter for conversion, a second rectifier for converting electric power received by the second power receiving coil unit into direct current, and a voltage of the direct-current power converted by the second rectifier are converted to DC A second DC-DC converter that performs DC conversion;
The absolute value of the coupling coefficient between the first power transmission coil and the first power reception coil is larger than the absolute value of the coupling coefficient between the first power transmission coil and the second power reception coil,
The absolute value of the coupling coefficient between the second power transmission coil and the second power reception coil is larger than the absolute value of the coupling coefficient between the second power transmission coil and the first power reception coil.
A control method for controlling a wireless power transmission device, comprising:
Voltage conversion of the first DC-DC converter based on a first detection value relating to the current amplitude of the first power transmission coil unit and a second detection value relating to the current amplitude of the second power transmission coil unit. A control method for controlling at least one of a ratio and a voltage conversion ratio of the second DC-DC converter.

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