JPWO2017017768A1 - Wireless power transmission device and control device - Google Patents

Abstract

A leakage magnetic field is reduced with a simple configuration. A wireless power transmission device according to an embodiment of the present invention includes: a plurality of coil units each including at least one coil; a plurality of power transmission circuits that supply power to the plurality of coil units; A measurement unit that measures a physical quantity according to the sum of currents flowing through the coil unit, and a control circuit that controls at least one of the plurality of power transmission circuits according to the physical quantity measured by the measurement unit.

Description

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

  There is known a wireless power transmission device that wirelessly transmits high-frequency energy from a coil on the power transmission side to a coil on the power reception side. Since energy can be supplied wirelessly from the power transmission side to the power reception side, convenience is improved, and there is an advantage that contact failure that becomes a problem in the case of wired communication is eliminated. In addition, when used in the vicinity of a passage where people are coming and going, people do not trip over the cable, so safety is also improved.

  In a conventional wireless power transmission apparatus, a method of reducing the magnetic field strength leaking to the surroundings by exciting a plurality of coils in opposite phases is known. In this method, the leakage magnetic field intensity at the observation point is reduced by establishing a relationship in which the radiated magnetic fields from a plurality of coils cancel each other at the observation point. Reduction of the leakage magnetic field may be necessary for reducing electromagnetic interference with other devices.

Patent registration No. 5139469

  However, when electric power is supplied to a plurality of coils by separate power transmission circuits, the current amplitude and the current phase flowing through the plurality of coils change depending on manufacturing variations and the positional relationship between the transmission and reception coils. As a result, the current amplitude and current phase flowing through the plurality of coils may deviate from their respective desired values, and the effect of reducing the leakage magnetic field at the observation point may be reduced.

  In this case, it is conceivable to adjust the current amplitude and the current phase flowing through the plurality of coils. For this purpose, it is necessary to observe the current flowing through each coil. In this case, a current probe for measuring the current is required for each coil, and there is a problem that a large number of current probes are required.

  An embodiment of the present invention aims to reduce a leakage magnetic field with a simple configuration.

  A wireless power transmission device according to an embodiment of the present invention includes a plurality of coil units each including at least one coil, a plurality of power transmission circuits that supply power to the plurality of coil units, and the plurality of coil units. A measurement unit that measures a physical quantity according to a sum of flowing currents and a control circuit that controls at least one of the plurality of power transmission circuits according to the physical quantity measured by the measurement unit.

The block diagram of the power transmission apparatus in the wireless power transmission apparatus which concerns on embodiment of this invention. The figure which shows the specific example of a coil part. The figure which shows the example of arrangement | positioning with the coil part by the side of power transmission, and the coil part by the side of a power receiving. The figure which shows the structural example of a current probe. The figure for demonstrating the example of the current sum of four electric currents. The figure for demonstrating another example of the current sum of four electric currents. The figure which shows the structural example of a power transmission circuit. The block diagram of the power transmission apparatus in the wireless power transmission apparatus which concerns on 2nd Embodiment. The block diagram of the power transmission apparatus in the wireless power transmission apparatus which concerns on 3rd Embodiment. The block diagram of the power receiving apparatus in the wireless power transmission apparatus which concerns on 4th Embodiment. FIG. 9 illustrates a configuration example of a power receiving circuit. The block diagram of the induction heating cooking apparatus which concerns on 5th Embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a wireless power transmission apparatus according to this embodiment. The wireless power transmission device includes a power transmission device that wirelessly transmits power to the power receiving device. The power transmission device is connected to the AC power supply device.

  The power transmission device includes N (N is an arbitrary positive number of 2 or more) power transmission circuits 1 to N (101-1, 101-2, ..., 101-N), and N coil units. 1 to N (102-1, 102-2,... 102-N), N first electric wires 1 to N (103-1, 103-2,... 103-N), and N wires Second electric wires 1 to N (104-1, 104-2,..., 104-N), a current probe 105 that is a measurement unit, and a control circuit 106. In this power transmission device, high-frequency current is supplied from the power transmission circuits 101-1 to 101-N to the coil units 102-1 to 102-N, and the magnetic fields generated in the coil units 102-1 to 102-N are arranged to face each other. By coupling to a plurality of coil portions of the power receiving device, power is transmitted wirelessly.

  The power transmission circuits 101-1 to 101-N generate an alternating current based on a constant alternating voltage supplied from an alternating current power supply device 111 such as a commercial power supply, and supply the alternating current to the coil units 102-1 to 102-N. To do. Each of the power transmission circuits 1 to N may be supplied with an AC voltage from a separate AC power supply, or may be supplied with an AC voltage from the same common AC power supply. The AC power supply device 111 in the figure includes any of these forms. The power transmission circuits 101-1 to 101-N include a high-frequency current output plus-side terminal and a minus-side terminal. In the present embodiment, the alternating current is a high-frequency current. However, as long as the alternating current is an alternating current, the alternating current may not be called a high-frequency current. The frequency of the high frequency current output from each power transmission circuit is the same or substantially the same. At least one of the amplitude and phase of the high-frequency current generated by each power transmission circuit is controlled by the control circuit 106.

  Coil units 102-1 to 102-N each include at least one coil. The coil portion is sometimes called a resonator. The coil unit may be the coil itself or may include elements other than the coil. For example, as shown in FIG. 2A, a capacitor 282 may be connected in series to one end side of the coil 292. The capacitor 282 may be connected in series to the opposite side of FIG. 2A, that is, the other end side of the coil 292. Capacitors 282a and 282b may be connected to both sides of the coil 292 as shown in FIG. 2B, or a plurality of coils 292a and 292b are connected in series as shown in FIG. The capacitor 282a may be connected in series. The coils 292, 292a, and 292b may be wound around the magnetic core. Configurations other than those described here may be used. As the coil shape, a coil having an arbitrary winding method capable of magnetic field coupling such as spiral winding or solenoid winding may be used. In the following description, it is assumed that the coil portion includes one coil for the sake of explanation, but the present invention is not limited to this.

  The first electric wires 103-1, 103-2,... 103-N, and the second electric wires 104-1, 104-2,. It is an electric wire which connects between coil parts 102-1 to 102-N. The first electric wire is connected to a plus-side terminal of the high-frequency current output of the power transmission circuit and a terminal on the winding start side of the coil in the coil portion. The second electric wire is connected to the negative terminal of the high-frequency current output on the power transmission circuit side and the terminal on the winding end side of the coil in the coil portion.

  FIG. 3A and FIG. 3B show an arrangement example of the coil portion on the power transmission side and the coil portion on the power reception side. Here, two coil parts are arranged on both the power transmission side and the power reception side. As the coil part on the power transmission side and the coil part on the power reception side, those obtained by winding a coil around a magnetic core are used. As shown in FIG. 3A, the opening surface of the coil portion on the power transmission side may be arranged to face the opening surface of the coil portion on the power reception side. Alternatively, as illustrated in FIG. 3B, the side surface of the power transmission side coil unit and the side surface of the power reception side coil unit may be arranged to face each other. FIG. 3C shows an example in which two coils (spiral coils) wound in a planar shape are arranged on the power transmission side and the power reception side, respectively, and these coils are arranged so that the opening surfaces face each other. In either case, as indicated by the broken lines in the figure, power is transmitted wirelessly by magnetic field coupling between the power transmitting and receiving coil portions.

  The current probe 105 in FIG. 1 is a measurement unit that measures a physical quantity corresponding to the sum of currents flowing through the coil units 102-1 to 102-N. Since the current flowing through the first electric wires 104-1 to 104-N flows to the coil sections 102-1 to 102-N, measuring the sum of the current flowing through the first electric wires 104-1 to 104-N is not possible. This is equivalent to measuring the sum of currents flowing through the coil sections 102-1 to 102-N. The current probe 105 is the sum of the induced currents generated in the conductive loop according to the current flowing through the coil units 102-1 to 102-N as a physical quantity corresponding to the sum of the currents flowing through the coil units 102-1 to 102-N. Measure.

FIG. 4 shows a configuration example of the current probe. The current probe includes a conductive loop and conductive wiring. The conductive wiring connects the conductive loop and the control circuit. As an example, the current probe may be composed of a Rogowski coil. When a Rogowski coil is used, a current probe that is resistant to disturbance can be configured.
The first electric wires 1 to N (104-1 to 104-N) are bundled in the loop, and electromagnetic induction is generated in the loop according to the current flowing through the first electric wires 1 to N (104-1 to 104-N). Current flows. That is, an induced electromotive force is generated that is proportional to the speed of change of the magnetic flux passing through the loop, and a current corresponding to the induced electromotive force and the resistance of the loop flows as the induced current. By measuring the total of the induced currents as the physical quantity, the sum of the currents flowing through the first electric wires 104-1 to 104-N, that is, the currents flowing through the coil portions 1 to N (102-1 to 102-N). The sum can be measured. That is, the value of the induction current and the value of the sum of the currents flowing through the first electric wires 1 to N (104-1 to 104-N) have a fixed relationship according to the relational expression of electromagnetic induction such as Faraday's law. Therefore, it can be said that measuring the value of the induced current is equivalent to measuring the sum of the currents flowing through the first electric wires 1 to N (104-1 to 104-N).

  The control circuit 106 controls the power transmission circuits 1 to N (101-1 to 101 -N) based on the current amplitude measured by the current probe 105. In this example, all of the power transmission circuits 1 to N (101-1 to 101-N) are controlled, but a configuration in which at least one of these power transmission circuits or a plurality of power transmission circuits is controlled is also possible. is there. The control circuit 106 performs control using the current amplitude of the output current, and information on the phase of the output current is not necessary here. Specifically, the control circuit 106 transmits the power transmission circuits 1 to N (101-1 to 101-101) so as to minimize the amplitude of the output current, to be equal to or less than a threshold value, or to be within a certain range. N) is controlled. The control circuit 106 determines the amplitude and / or phase of the high-frequency current output from each power transmission circuit, and outputs the determined amplitude and / or phase instructions to each power transmission circuit. Each power transmission circuit generates and outputs a high-frequency current with an amplitude and / or a phase in accordance with an instruction from the control circuit 106. Thereby, the value of the sum of the currents flowing through the respective coil portions can be minimized, less than a desired value, or within a desired range, and the strength of the leakage magnetic field can be reduced.

  The fact that the strength of the leakage magnetic field can be reduced will be described in more detail. The strength of the magnetic field generated from the coil is proportional to the amplitude of the current flowing through the coil. Therefore, if the sum of currents flowing through the plurality of coils is minimized, the combined strength of the magnetic fields generated from these coils is also minimized. As described above, in the present embodiment, a physical quantity (total of induced currents generated in the conductive loop) corresponding to the sum of currents flowing through the coil units 1 to N (102-1 to 102-N) is measured. Since this measured current is controlled to be minimized, below the threshold value, or controlled within a predetermined range, the sum of the magnetic field strengths generated from the coil units 1 to N (102-1 to 102-N) is also minimized, to a desired value or less. Or, it is controlled within a desired range.

  Here, if the winding direction of the coil in each coil part is different, the relationship described above, that is, the relationship in which the sum of the magnetic field strengths becomes smaller as the sum of the current strengths becomes smaller is not established. For this reason, in this embodiment, suppose that the coil in each coil part has the same arrangement configuration. The same arrangement configuration means, for example, that the winding direction, the number of windings, and the relative positions of the winding start and winding end are equal.

An example of the current sum when N = 4 will be described with reference to FIG. FIG. 5 shows amplitudes and phases of currents I ₁ , I ₂ , I ₃ , and I ₄ flowing through the first electric wires 1 to N. The amplitudes of the currents flowing through the four first electric wires 1 to N are equal, and the phase difference is different by 90 degrees. In this case, the combined current of the currents flowing through the first electric wires 1 to N is zero. Therefore, it can be said that the combined magnetic field intensity generated from the coil portions 1 to 4 is also zero.

FIG. 6 shows a case where N = 4 as in FIG. 5, but unlike the example of FIG. 5, the amplitudes of the currents I ₁ , I ₂ , I ₃ and I ₄ flowing through the four first electric wires 1 to N are different. Is different. Further, the phase difference is not shifted by 90 degrees. In this case, the amplitude of the current measured by the current probe 105 is not 0 but a certain finite value. In this embodiment, in such a case, the power transmission circuits 1 to N are controlled so that the measurement current of the current probe is minimized by the control circuit. Thereby, the amplitude and / or phase of the current flowing through the first electric wires 1 to N can be adjusted, and as a result, the combined current can be minimized.

  Here, an operation example of the control circuit 106 in the case where the sum of currents flowing through the coil units 1 to N is minimized will be described. A case where N = 2 and a case where N = 4 will be described.

  First, an operation example when N = 2 will be described. First, the control circuit 106 measures the current of the current probe 105 in an initial state (that is, measures the combined current of the coil units 1 to N). Next, with the current amplitudes of the two power transmission circuits being fixed, only the current phase of the second power transmission circuit is changed, and the phase that minimizes the current of the current probe 105 is determined. Since N = 2, the current phase difference is set to 180 degrees or approximately 180 degrees.

  Next, while only the current phase difference between the two power transmission circuits is fixed, only the current amplitude from the second power transmission circuit is changed so that the measured current value of the current probe 105 is minimized. When the current amplitude from the second power transmission circuit matches or substantially matches the current amplitude from the first power transmission circuit, the measured current value of the current probe 105 is minimized (the current sum of the two coil portions is minimized). The

  As described above, the control circuit 106 controls the two power transmission circuits, whereby the current sum of the two coil portions is minimized. As a result, the combined magnetic field strength leaking from the two coil portions is also minimized.

  Next, an operation example of the control circuit 106 when N = 4 and minimizing the current sum of the plurality of coil portions will be described. Needless to say, when the current sum is minimized, it is necessary to control under the condition that the current amplitudes of the respective power transmission circuits are not all zero. This is because wireless power transmission is not performed when the current amplitude of each power transmission circuit is all zero. In this operation example, a lower limit threshold and an upper limit threshold for the current amplitude to be set are given in advance. The amplitude value of the rated current may be used as the upper threshold value.

The control circuit 106 sets a plurality of current amplitudes to be set for each power transmission circuit within the range between the lower limit threshold and the upper limit threshold. For example, five current amplitudes are set between the lower limit threshold and the upper limit threshold for each power transmission circuit. Thereby, when N = 4, 5 ⁴ = 625 combinations of current amplitudes are obtained. As for the phase, the target is to shift the phase difference by 90 degrees in each power transmission circuit as in the example of FIG. In this case, for example, four phase values of −10 degrees, −5 degrees, +5 degrees, and +10 degrees are set before and after the phase setting value in which the phase difference is shifted by 90 degrees. That is, five phases of −10 degrees, −5 degrees, 0 degrees, +5 degrees, and +10 degrees are set for each power transmission circuit. Since N = 4, 5 ⁴ = 625 current phase combinations are obtained.

  Since there are 625 combinations of current amplitude and 625 combinations of current phase, 625 × 625 = 390625 combinations of current amplitude and current phase can be set between the four power transmission circuits. From this combination, the control circuit 106 may select a combination that minimizes the measured current value of the current probe (the current sum of the four coil portions is minimum).

  The method for minimizing the current sum of the plurality of coil portions is not limited to the above example, and any method can be used. Also, the number of coil portions may be three, or five or more.

  As described above, according to the present embodiment, the physical quantity corresponding to the sum of the currents of the plurality of coil units is measured using one current probe, and the amplitude or phase of the output current of each power transmission circuit or the By controlling both of these, the combined strength of the leakage magnetic fields from the plurality of coil portions can be reduced. Since it is not necessary to arrange a current probe for each coil part (for each first electric wire), the configuration can be simplified and the cost can be reduced. Further, since it is not necessary to compare the output values of the current probes measured for each coil part, it is possible to use a probe with low current amplitude measurement accuracy. In addition, there is an advantage that the control is performed using only the amplitude of the output value of one current probe, and the phase measurement of the current of each coil part is unnecessary.

  In the description of the operation example of the control circuit 106 described above, the control circuit adjusts both the current amplitude and the current phase output from each power transmission circuit, but a configuration in which only one of them is controlled is also possible. In this case, there is an advantage that the configuration of the power transmission circuit is simplified. On the other hand, there may be a case where the leakage magnetic field strength cannot be minimized. However, in this case as well, the present embodiment is effective when the target value for reducing the leakage magnetic field strength is small.

  FIG. 7 shows a configuration example of the power transmission circuit. Any of the power transmission circuits 1 to N described above can have the configuration of FIG. The power transmission circuit includes a converter (AC-DC conversion circuit) 501, a step-up / down circuit 502, and an inverter circuit 503. With this configuration, the current amplitude and current phase of the output of the power transmission circuit can be changed.

  Converter (AC-DC conversion circuit) 501 receives, for example, AC voltage 100V or AC voltage 200V from commercial AC power supply 500 as an input. The converter 501 converts the AC voltage into a constant DC voltage. The converter of each power transmission circuit may be supplied with an AC voltage from a separate AC power supply, or may be supplied with an AC voltage from a common AC power supply.

  The step-up / down circuit 502 is a DC-DC conversion circuit that receives a DC voltage having a constant voltage value as input, converts the voltage to a voltage higher than the input voltage, the same voltage, or a lower voltage, and outputs the converted voltage.

  The inverter circuit 503 is a circuit that outputs a high frequency voltage using the output voltage of the step-up / down circuit 502 as an input. This high frequency voltage is supplied to the coil section.

  Although the operation of each circuit has been described using voltage, the description is omitted because it is the same for current.

  The voltage conversion ratio of the step-up / down circuit 502 can be controlled by the control circuit 106 of FIG. That is, since the output voltage of the converter 501 is constant, the output voltage of the buck-boost circuit 502 can be controlled by controlling the conversion ratio. Since the output voltage of the inverter circuit 503 is proportional to the input voltage of the inverter circuit 503, the input voltage of the inverter circuit 503 is changed by controlling the voltage conversion ratio of the step-up / step-down circuit 502. The output voltage also changes. When the output voltage of the inverter circuit 503 changes, the output current of the inverter circuit 503 also changes according to Ohm's law. Therefore, it is possible to change the output current amplitude of the inverter circuit 503 by controlling the voltage conversion ratio of the step-up / down circuit 502. Whether the output current amplitude is reduced or increased when the conversion ratio is increased or decreased can be any configuration depending on the circuit configuration. As an example, the conversion ratio is defined as the output voltage of the buck-boost circuit 502 / the input voltage of the buck-boost circuit 502, but is not limited thereto. “/” Means division.

The inverter circuit 503 includes a plurality of switches, and an AC voltage waveform is output by switching these switches. By controlling the switching timing of these switches, the frequency of the output voltage waveform can be controlled. Therefore, the phase of the output AC voltage waveform can be made different by changing the timing of the switching timing among the plurality of inverter circuits. For example, if the switching timing is the same in each inverter circuit of two power transmission circuits, the phases of the outputs are the same. If the switching timing differs by a quarter of the AC cycle, the output phase difference is 90 degrees. Similarly, if the switching timing is different by a half of the AC cycle, the output phase difference is 180 degrees. In the present embodiment, the output frequency of the inverter circuit of each power transmission circuit is the same or substantially the same.
In this way, the phase of the output voltage can be changed by controlling the switching timing of the inverter circuit. By changing the output voltage, the phase of the output current of the inverter circuit also changes, thereby making it possible to change the output current phase of the power transmission circuit.

(Second Embodiment)
FIG. 8 is a block diagram of a power transmission device according to the second embodiment. Here, the configuration in the case of N = 2 is shown. In the configuration of FIG. 1, the current probe measures a physical quantity (total of induced currents generated in the conductive loop) according to the sum of the currents of the first electric wires 1 to N, but the current probe 651 of FIG. The sum of currents of the first electric wire 1 (103-1) and the second electric wire 2 (104-1) is measured as the physical quantity. The control circuit 652 controls at least one of the amplitude and the phase of the output current of the power transmission circuits 1 and 2 so that the current amplitude measured by the current probe 651 is maximized, is equal to or greater than a threshold value, or falls within a certain range. As a result, the combined strength of leakage magnetic fields from the coil portions 1 and 2 is reduced. Here, the configuration in the case of N = 2 is shown, but the present invention can be similarly applied to the case where N is another value, such as the case of N = 4.

  The first electric wire 1 and the second electric wire 2 are passed through the loop of the current probe 651. The currents flowing through the first electric wire 1 and the second electric wire 2 are in opposite directions. Therefore, when the sum of the current flowing through the first electric wire 1 and the current flowing through the second electric wire 2 is maximized, the combined strength of the leakage magnetic fields from the coil portions 1 and 2 is minimized. In order to maximize the sum of currents (that is, to maximize the current measured by the current probe 651), it is only necessary to adjust at least one output current phase of the two power transmission circuits 1 and 2. Since the current sum increases as the output current amplitude of the power transmission circuits 1 and 2 is increased, the output current amplitude of the power transmission circuits 1 and 2 may be fixed in advance.

  Thus, by maximizing the measurement current of the current probe, it is possible to use a current probe with a small sensitivity range. For example, when the measurement current is minimized as shown in FIG. 1, the current of the current probe can take zero or a value close to zero, so that it is required to be able to detect the value. Further, for the purpose of minimizing the measurement current, it is considered that the current probe only needs to detect the value Imax corresponding to the maximum current that can be output by at least one power transmission circuit. Therefore, since the ratio between Imax and the value close to zero is very large, a current probe having a large sensitivity range is required. On the other hand, when maximizing the measurement current as in the second embodiment, it is necessary to be able to detect Imax × N (N = 2 in the example of FIG. 8) as the maximum value required for detection, and the minimum value It is considered that the above-described Imax may be detected. The ratio between Imax × N and Imax is N (N = 2 in the example of FIG. 3). Therefore, a current probe having a small sensitivity range can be used as a current probe used to maximize the current sum.

  Although FIG. 8 shows the case of N = 2, when N = 4, for example, the first electric wire 3 and the second electric wire 4 (see FIG. 1) may be additionally passed through the current probe 651. It is also possible to select an electric wire that passes the current probe 651 for each power transmission circuit by a method other than the method described here.

  As described above, according to the present embodiment, the leakage magnetic field strength can be reduced by controlling the current phase of each power transmission circuit so as to maximize the current measured by the current probe.

(Third embodiment)
FIG. 9 is a block diagram of a power transmission device according to the third embodiment. In the first embodiment, the current probe (measurement unit) 105 measures the sum of the induced currents generated in the conductive loop as a physical quantity corresponding to the current sum of the plurality of coil units, but in this embodiment, the measurement unit 109 However, the voltage of the predetermined path | route over the 1st electric wires 1-N is measured as the said physical quantity. The control circuit 110 controls the amplitude, phase, or both of the output currents of the power transmission circuits 1 to N so that the voltage measured by the measurement unit 109 is minimum, below the threshold value, or within a predetermined range. .

  Resistive elements R1 to RN are arranged on the first electric wires 1 to N. One terminal of the resistance element R1 (terminal on the coil part side) and a terminal opposite to the one terminal of the resistance element R1 of the resistance element R2 (terminal on the power transmission circuit side) are connected by the wiring H1. The other terminal (terminal on the coil portion) of the resistor element R2 and a terminal opposite to the other terminal (terminal on the power transmission circuit) side of the resistor element R2 of the resistor element R3 (not shown) are wires H2. Connected (when N is 3 or more). More generally, between the first to Nth first electric wires, one terminal of the resistance element of the Xth (X is an integer less than or equal to 1 and less than N) first electric wire and the resistance of the (X + 1) th first electric wire. The one terminal of the element and the terminal on the opposite side are connected by a wiring X.

  The measuring unit 109 measures the voltage between the other terminal of the resistance element R1 (terminal opposite to the side where the wiring is connected) and the terminal opposite to the side where the wiring of the resistance element RN is connected. taking measurement. Thereby, the voltage of the predetermined path | route via the resistive element on each 1st electric wire is measured between the some 1st electric wires 1. FIG.

  The control circuit 110 controls the amplitude, phase, or both of the output currents of the power transmission circuits 1 to N so that the voltage measured by the measurement unit 109 is minimum, below the threshold value, or within a predetermined range. . For example, consider the case of N = 2. At this time, when the voltage measured by the measurement unit 109 is minimized, the voltage is, for example, zero. At this time, the phase difference between the currents flowing through the first electric wire 1 and the first electric wire 2 is 180 degrees. The amplitude of the current is the same. The detailed operation of the control circuit 110 is basically the same as that in the first embodiment in which the sum of currents is minimized, and thus the description thereof is omitted.

(Fourth embodiment)
FIG. 10 shows a wireless power transmission apparatus according to the fourth embodiment. The wireless power transmission device includes a power receiving device that wirelessly receives power from the power transmitting device. The power receiving device is connected to the load device 611.

  The power receiving device includes N (N is an arbitrary positive number of 2 or more) power receiving circuits 1, 2,... N (601-1, 601-2,..., 601-N), N coil portions 1, 2,... N (602-1, 602-2,... 602-N) and N first electric wires 1, 2,... N (603-1, 603-2,... 603-N), N second electric wires 1, 2,... N (604-1, 604-2,... 604-N), and a current probe 605. And a control circuit 606. Except that the power transmission circuit of FIG. 1 is changed to a power reception circuit, the connection relationship between the elements is the same as that of the power transmission device of FIG.

  This power receiving device includes coil portions 1 to N (602-1, 602-2,... 602-N), and coil portions 1 to N (102-1 to 102-N) of power transmission devices arranged to face each other (see FIG. 1) and magnetic field coupling. By this magnetic field coupling, an electromotive force (voltage) is generated in the coil portions 1 to N (602-1, 602-2,... 602-N), and a high-frequency current corresponding to the electromotive force flows. Thus, power is received wirelessly from the power transmission device. The high-frequency current generated in each coil unit is supplied to the power receiving circuits 1 to N (601-1 to 601 -N) and converted into direct current. The converted direct current is supplied to the subsequent load device 611. The load device 611 may be a resistor (electronic device or the like) that consumes power, or a storage battery that charges power. In the present embodiment, the combined strength of magnetic fields leaking from the coil units 1 to N that receive power transmitted from the power transmission device is reduced. In FIG. 10, the power receiving circuits 1 to N are connected to the same load device, but may be configured to be connected to a different load device for each power receiving circuit.

  Similarly to the first embodiment, the current probe 605 measures the sum of the induced currents generated in the conductive loop as a physical quantity corresponding to the sum of currents flowing through the first electric wires 1 to N. As in the first embodiment, for example, the configuration of FIG. 4 can be used for the current probe 605. For example, a Rogowski coil may be used as the current probe 605. When a Rogowski coil is used, a current probe that is resistant to disturbance can be configured.

  The control circuit 606 controls the power receiving circuits 1 to N so that the current measured by the current probe 605 is minimum, below the threshold value, or within a predetermined range. Thereby, the combined strength of the leakage magnetic field generated from each coil part is reduced. For example, when the current measured by the current probe 605 is minimized, the combined strength of the leakage magnetic field is minimized.

  FIG. 11 illustrates a configuration example of the power receiving circuit. Any of the power receiving circuits 1 to N described above can have the configuration of FIG. The power receiving circuit includes a rectifier circuit 701 and a step-up / step-down circuit (DC-DC conversion circuit) 702. The rectifier circuit 701 receives a high-frequency current generated in the coil unit and converts the high-frequency current into a direct current. As a result, a constant DC voltage is output from the rectifier circuit 701. The step-up / down circuit 702 receives the constant DC voltage output from the rectifier circuit 701 as an input, and outputs a voltage that is higher, the same as, or lower than the input voltage. A load device is connected to the subsequent stage of the step-up / down circuit 702.

  The voltage conversion ratio of the step-up / step-down circuit 702 can be controlled by the control circuit 606 in FIG. 10, and the current amplitude of the coil section can be controlled by changing the voltage conversion ratio. That is, when the conversion ratio is changed, the ratio of the voltage and current supplied to the load device is changed. This is equivalent to a change in the value of the load when viewed from the coil part, and the impedance of the coil part from the load side is changed. For this reason, the amplitude of the current flowing through the coil section can be changed (the amplitude of the current output from the power transmission circuit also changes accordingly). With this configuration, the current amplitude flowing from the control circuit 606 to the coil portion can be changed. Whether the current amplitude decreases or increases when the conversion ratio is increased or decreased may be any configuration depending on the circuit configuration. As an example, the conversion ratio is defined as the output voltage of the buck-boost circuit 702 / the input voltage of the buck-boost circuit 702, but is not limited thereto. “/” Means division.

  As described above, according to the present embodiment, the combined strength of the magnetic fields leaking from the plurality of coil portions on the power receiving side can be reduced by the control on the power receiving side.

(Fifth embodiment)
FIG. 12 shows an induction heating cooking apparatus according to the fifth embodiment. Elements similar to those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted. This device has the same configuration as that of the power transmission device of FIG. 1, but does not wirelessly transmit power to the power receiving side, but rather a metal cooking pot 801 via a cooking table 811 so as to face each coil unit. -1, 801-2,... 801-N are arranged, and these cooking pots are induction-heated. Magnetic field lines generated in response to the high-frequency current flowing in each coil section pass through each cooking pan, and an eddy current flows on the surface of the metal material of the cooking pan, whereby the cooking pan generates heat. The control circuit 106 operates in the same manner as the control circuit of the power transmission device in FIG. Thereby, the intensity | strength of the magnetic field leaked around the induction heating cooking apparatus can be reduced. Therefore, the control device according to the present embodiment can be applied as a control circuit of a wireless power transmission device or a control circuit of an induction heating cooking device.

(Other)
In each of the above-described embodiments, it is assumed that the coils of each coil portion have the same shape and are wound in the same direction. However, each embodiment can be used even when the shapes of the coils are different from each other. is there. For example, assume that N = 2 in the power transmission device. The first coil has a number of turns 1, and the second coil has a number of turns 2. The conditions other than the number of turns are the same. Since the magnetic field strength is proportional to the number of turns of the coil, when currents of the same magnitude flow through the coils 1 and 2, the magnetic field strengths generated from the coils 1 and 2 are twice different. Therefore, under this condition, the current sum of these coils may be measured with a current probe, with the measurement sensitivity of the first coil being doubled and the measurement sensitivity of the second coil being doubled.

  As a method of increasing the current sensitivity of a coil using a current probe, there is a method of increasing the number of times of winding an electric wire around the current probe. For example, if the electric wire is wound twice around the current probe, the measurement sensitivity is doubled and a current value is doubled.

  Therefore, the physical quantity corresponding to the current sum of these coils is measured with the current probe while the electric wire of the first coil is wound around the current probe twice and the electric wire of the second coil is passed through the current probe once. Then, the current sum of these coils may be minimized. Thereby, even when the shape of each coil differs, the leakage magnetic field strength can be reduced.

  In each embodiment, high-frequency current (high-frequency energy) is generated from the power transmission circuit, but harmonics are generated in addition to the fundamental frequency with respect to the frequency characteristics of the high-frequency current. In each embodiment, focusing on the current at the fundamental frequency in the output current of the current probe, it is assumed that the magnetic field strength at the fundamental frequency is reduced. This can be done by extracting the fundamental frequency component from the measurement current of the current probe and measuring the amplitude of the extracted component. As another example, it is possible to reduce the harmonic magnetic field intensity by focusing on the harmonic current in the current detected by the current probe. In this case, the power transmission circuit or the power reception circuit may be controlled such that the power transmission side control circuit or the power reception side control circuit minimizes the amplitude of the harmonic current in the output current of the current probe.

  In each embodiment, the physical quantity corresponding to the current sum of each coil part is measured with one current probe. However, when the number of coil parts is large or the thickness of each electric wire is large, the current probe The size may increase. Therefore, for example, when N = 10, it is divided into two groups of five wires, each group is measured with a separate current probe, and the measured currents (output currents) of the two current probes are combined. Good.

  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.

101-N: power transmission circuits 102-1, 102-2,... 102-N: coil sections 103-1, 103-2,... 103-N: No. , 104-N: second electric wire 105, 651: current probe (measurement unit)
106: Control circuit (control device)
109: Measuring unit 111: AC power supply devices 282, 282a, 282b: Capacitors 292, 292a, 292b: Coil 500: AC power supply 501: Converter 502: Buck-boost circuit 503: Inverter circuits R1-RN: Resistance elements H1-HN: Wiring 601-1, 601-2,..., 601-N: power receiving circuits 602-1, 602-2,... 602-N: coil units 603-1, 603-2,. 1 electric wire 604-1, 604-2, ..., 604-N: second electric wire 605: current probe (measurement unit)
606: Control circuit (control device)
701: Rectifier circuit 702: Buck-boost circuit 811: Cooking table 801-1, 801-2, ... 801-N: Cooking pan

Claims (17)

A plurality of coil portions each including at least one coil;
A plurality of power transmission circuits for supplying power to the plurality of coil sections;
A measurement unit that measures a physical quantity according to a sum of currents flowing through the plurality of coil units;
A control circuit that controls at least one of the plurality of power transmission circuits according to the physical quantity measured by the measurement unit;
A wireless power transmission device comprising: 2. The control circuit according to claim 1, wherein the control circuit controls at least one of the plurality of power transmission circuits so that a value of the measured physical quantity is minimized, is less than a threshold value, or falls within a predetermined range. Wireless power transmission device. The plurality of power transmission circuits are connected to first ends of the plurality of coil portions via a plurality of first electric wires, and are connected to second ends of the plurality of coil portions via a plurality of second electric wires. ,
The measurement unit includes a current probe including a conductive loop surrounding one of the first electric wire and the second electric wire selected for each of the plurality of coil units, and is surrounded by the conductive loop. The wireless power transmission device according to claim 1, wherein the physical quantity that is a sum of currents flowing through the electric wires is measured. The wireless power transmission device according to any one of claims 1 to 3, wherein the control circuit controls at least one of an amplitude and a phase of a current generated by at least one of the plurality of power transmission circuits. Each of the plurality of power transmission circuits is
An AC-DC conversion circuit that receives an AC voltage and converts the AC voltage into a DC voltage;
A DC-DC conversion circuit for stepping up or stepping down the voltage converted by the AC-DC conversion circuit;
An invar circuit that generates an alternating voltage based on the voltage converted by the DC-DC conversion circuit,
The control circuit controls the amplitude of the current generated by at least one of the plurality of power transmission circuits by adjusting a voltage conversion ratio of at least one DC-DC conversion circuit of the plurality of power transmission circuits. 4. The wireless power transmission device according to 4. Each of the plurality of power transmission circuits is
An AC-DC conversion circuit that receives an AC voltage and converts the AC voltage into a DC voltage;
A DC-DC conversion circuit for stepping up or stepping down the voltage converted by the AC-DC conversion circuit;
An invar circuit that outputs an alternating voltage by switching a switch based on the voltage converted by the DC-DC conversion circuit,
The control circuit controls a phase of the current generated by at least one of the plurality of power transmission circuits by controlling switching timing of the switch in at least one of the inverter circuits of the plurality of power transmission circuits. The wireless power transmission device according to 1. The plurality of power transmission circuits which are N (N is an integer of 2 or more) are connected to the first ends of the plurality of coil portions via first to Nth first electric wires, and the first to Nth Connected to the second ends of the plurality of coil portions via a second electric wire,
Each of the first to Nth first electric wires includes a resistance element;
Connect one terminal of the resistance element of the first electric wire of the Xth (X is an integer of 1 or more and less than N) and a terminal opposite to one terminal of the resistance element of the X + 1th electric wire. First to (N-1) th wirings,
The measurement unit includes a terminal on the opposite side to the side where the first wiring of the resistance element included in the first first electric wire is connected, and the resistance element included in the Nth first electric wire. The wireless power transmission device according to claim 1, wherein the physical quantity that is a voltage between a terminal connected to the N-1th wiring and a terminal on the opposite side is measured. The control circuit controls a phase of a current generated by at least one of the plurality of power transmission circuits so that a value of the measured physical quantity is maximized, exceeds a threshold value, or falls within a predetermined range. Item 7. The wireless power transmission device according to any one of Items 1, 3, and 6. A plurality of coil portions each including at least one coil;
A plurality of power receiving circuits for performing a process including a process of converting the power received by the plurality of coil units into a direct current;
A measurement unit that measures a physical quantity according to a sum of currents flowing through the plurality of coil units;
A control circuit that controls at least one of the plurality of power receiving circuits according to the physical quantity measured by the measurement unit;
A wireless power transmission device comprising: 10. The wireless power according to claim 9, wherein the control circuit controls at least one of the plurality of power transmission circuits so that the value of the physical quantity becomes a minimum value, a threshold value or less, or falls within a predetermined range. Transmission equipment. The plurality of power receiving circuits are connected to first ends of the plurality of coil portions via a plurality of first electric wires, and are connected to second ends of the plurality of coil portions via a plurality of second electric wires. ,
The measurement unit includes a current probe including a conductive loop surrounding one of the first electric wire and the second electric wire selected for each of the plurality of coil units, and is surrounded by the conductive loop. The wireless power transmission device according to claim 9 or 10, wherein the physical quantity that is a sum of currents flowing through electric wires is measured. The wireless power transmission device according to any one of claims 9 to 11, wherein the control circuit controls a current amplitude of power received by at least one of the plurality of power receiving circuits. Each of the plurality of power receiving circuits is
A rectifier circuit for converting the received power from AC to DC;
A DC-DC conversion circuit that boosts or steps down the voltage of the DC power converted by the rectifier circuit,
The control circuit controls an amplitude of a current of the power received by at least one of the plurality of power receiving circuits by adjusting a conversion ratio of the DC-DC conversion circuit of at least one of the plurality of power receiving circuits. The wireless power transmission device according to claim 12. The plurality of power receiving circuits that are N (N is an integer of 2 or more) are connected to first ends of the plurality of coil portions via first to Nth first electric wires, and Connected to the second ends of the plurality of coil portions via a second electric wire,
Each of the first to Nth first electric wires includes a resistance element;
Connect one terminal of the resistance element of the first electric wire of the Xth (X is an integer of 1 or more and less than N) and a terminal opposite to one terminal of the resistance element of the X + 1th electric wire. First to (N-1) th wirings,
The measurement unit includes a terminal on the opposite side to the side where the first wiring of the resistance element included in the first first electric wire is connected, and the resistance element included in the Nth first electric wire. The wireless power transmission device according to claim 11, wherein the physical quantity that is a voltage between a terminal connected to the N-1th wiring and a terminal on the opposite side is measured. A control device that controls a device that includes a plurality of coil units each including at least one coil and a plurality of power transmission circuits that supply power to the plurality of coil units,
A measurement unit that measures a physical quantity according to a sum of currents flowing through the plurality of coil units;
A control circuit that controls at least one of the plurality of power transmission circuits according to the physical quantity measured by the measurement unit;
A control device comprising: The control device according to claim 15, wherein the device is a power transmission device or induction heating cooking device for wireless power transmission. A control device for a power receiving device for wireless power transmission, comprising: a plurality of coil units each including at least one coil; and a plurality of power receiving circuits for controlling power received by the plurality of coil units,
A measurement unit that measures a physical quantity according to a sum of currents flowing through the plurality of coil units;
A control circuit that controls at least one of the plurality of power receiving circuits according to the physical quantity measured by the measurement unit;
A control device comprising:

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