Wireless power supply inverter, wireless power supply inverter control method, and wireless power supply device

Abstract

To suppress the deterioration of the load power factor of a composite resonant circuit connected to a wireless power supply inverter and to improve the load power factor of the composite resonant circuit.SOLUTION: The wireless power supply inverter using a composite resonant circuit having a power transmission resonant circuit and a power reception resonant circuit includes an inverter circuit to which the composite resonant circuit having the power transmission resonant circuit and the power reception resonant circuit is connected, and control means for controlling the operation of the inverter circuit. The control means operates the inverter circuit at n (where "n" is a positive integer of 2 or greater) different frequencies within a preset frequency range m times or less ("m" is a positive integer, where m≤n) for a short time. It measures the load power factor and load impedance of the composite resonant circuit during these short-duration operations. On the basis of the comparison results of the measured load power factor and load impedance against the thresholds, it selects the output frequency.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a wireless power supply inverter, a control method for a wireless power supply inverter, and a wireless power supply device.

[0002] More specifically, the present invention relates to a wireless power supply inverter that uses a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit connected thereto, a control method for the wireless power supply inverter, and a wireless power supply device that includes the wireless power supply inverter. [Background technology]

[0003] Conventionally, as a wireless power supply device for supplying power to various power supply targets such as a battery mounted on an electric vehicle (EV), for example, a wireless power supply device having a configuration shown in FIG. 1 has been known.

[0004] That is, FIG. 1 shows an explanatory diagram of the configuration of a wireless power supply device equipped with a fixed single frequency inverter, which is a conventionally known inverter for wireless power supply.

[0005] The wireless power feeder 100 shown in FIG. 1 includes an alternating current (AC) power supply (a three-phase AC power supply is shown in FIG. 1), a converter 104 connected to the AC power supply 102 and receiving AC voltage supplied from the AC power supply 102, converting it to a direct current (DC) voltage, and outputting the DC voltage, a conventionally known wireless power feed inverter 106 connected to the converter 104 and receiving the DC voltage output from the converter 104, and inversely converting it to a high-frequency AC voltage, and outputting the high-frequency AC voltage (for ease of explanation, this conventionally known wireless power feed inverter will be referred to as a “fixed single frequency inverter”), a composite resonant circuit 108 connected to the fixed single frequency inverter 106 and transmitting and receiving the output from the fixed single frequency inverter 106, a rectifier circuit 110 connected to the composite resonant circuit 108 and rectifying the output from the composite resonant circuit 108, and a battery 112 connected to the rectifier circuit 110 and mounted on an EV that is the power feed target and receives the output from the rectifier circuit 110.

[0006] Here, the fixed single frequency inverter 106 mentioned above means an inverter whose output frequency is constant, in other words, whose output frequency is fixed at one specific frequency.

[0007] The composite resonant circuit 108 is configured to include a power transmitting resonant circuit (power transmitting coil) 108a connected to the fixed single frequency inverter 106 side, and a power receiving resonant circuit (power receiving coil) 108b connected to the rectifier circuit 110 side.

[0008] In the above configuration, the wireless power supply device 100 described above can supply power from the alternating current (AC) power supply 102 to the battery 112.

[0009] However, in the wireless power feeder 100 described above, the fixed single-frequency inverter 106, which is an inverter for wireless power feed, has an output frequency fixed at one frequency. Therefore, if the distance L between the power transmitting resonant circuit 108a and the power receiving resonant circuit 108b that constitute the composite resonant circuit 108, i.e., the distance L between the power transmitting and receiving coils, changes and the coupling coefficient k determined by the distance L changes, the load power factor of the composite resonant circuit 108 deteriorates.

[0010] When the load power factor of the composite resonant circuit 108 deteriorates in this way, the output kVA of the fixed single frequency inverter 106 increases, causing an increase in the output current, or the output loss of the fixed single frequency inverter 106 increases, resulting in problems such as an increase in the allowable loss of the switching elements of the inverter circuit that constitutes the fixed single frequency inverter 106, an increase in the output current, and an increase in output noise.

[0011] In wireless power supply for EVs, it is generally common to avoid changing the frequency while power supply is in operation to prevent noise, and it has been required to operate at a fixed frequency.

[0012] In addition, the prior art that the applicant of the present application knew at the time of filing the patent application is not an invention related to an invention publicly known in a literature, and therefore there is no prior art literature information to be described in the present specification. Summary of the Invention [Problem to be solved by the invention]

[0013] The present invention has been made in consideration of the various problems in the conventional technology as described above, and an object of the present invention is to provide a wireless power supply inverter that suppresses deterioration of the load power factor of a complex resonant circuit connected to the wireless power supply inverter and improves the load power factor of the complex resonant circuit, a control method for the wireless power supply inverter, and a wireless power supply device including the wireless power supply inverter. [Means for solving the problem]

[0014] In order to achieve the above object, the present invention provides a wireless power supply inverter used in a wireless power supply device having a composite resonant circuit, in which, based on measured values ​​of the load power factor and load impedance of the composite resonant circuit connected to the wireless power supply inverter, the output frequency of the wireless power supply inverter is selected so as to suppress deterioration of the load power factor of the composite resonant circuit and improve the load power factor of the composite resonant circuit.

[0015] Therefore, according to the present invention, an output frequency that can suppress deterioration of the load power factor of the composite resonant circuit and improve the load power factor of the composite resonant circuit is selected as the output frequency of the inverter for wireless power supply. Therefore, by determining the selected output frequency as the output frequency during power supply operation and performing the power supply operation, it becomes possible to suppress deterioration of the load power factor of the composite resonant circuit and improve the load power factor of the composite resonant circuit, and to eliminate adverse effects such as an increase in the allowable loss of the switching element of the inverter circuit, an increase in output current, and an increase in output noise.

[0016] That is, the wireless power supply inverter according to the present invention is a wireless power supply inverter used by connecting a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit. The inverter circuit has an inverter circuit to which the composite resonant circuit having the power transmitting resonant circuit and the power receiving resonant circuit is connected, and a control means for controlling the operation of the inverter circuit, and the control means operates the inverter circuit for a short time m ("m" is a positive integer of 2 or more) or less times at n different frequencies ("n" is a positive integer of 2 or more) within a predetermined frequency range, measures the load power factor and load impedance of the composite resonant circuit by the short-time operation, and selects an output frequency based on the comparison result obtained by comparing the measured load power factor and load impedance with their respective thresholds.

[0017] Furthermore, the wireless power supply inverter according to the present invention is the above-described wireless power supply inverter according to the present invention, which is operated for a first short time (m=1) at a frequency in a frequency band near the middle of the above-described preset frequency range.

[0018] Furthermore, the wireless power supply inverter according to the present invention is the above-described wireless power supply inverter according to the present invention, wherein when the comparison result shows that the load power factor is equal to or greater than a threshold value, a frequency at which the load power factor is equal to or greater than a threshold value is selected as an output frequency, and when the comparison result shows that the load power factor is less than the threshold value, a frequency at which the load impedance is equal to or greater than a threshold value is selected as an output frequency.

[0019] Furthermore, the wireless power supply inverter according to the present invention is the above-described wireless power supply inverter according to the present invention, wherein when switching the frequency when operating for a short period of time of m times or less, the output of the inverter circuit is temporarily turned off before switching the frequency.

[0020] Furthermore, the wireless power supply inverter according to the present invention is the above-described wireless power supply inverter according to the present invention, wherein when switching the frequency when operating for a short period of time of m times or less, the output of the inverter circuit is not temporarily turned off, but the frequency is switched with the output of the inverter circuit lowered.

[0021] Further, in a control method for a wireless power supply inverter according to the present invention, a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit is connected and used, and the inverter circuit is operated for a short time m ("m" is a positive integer, where "m≦n") times or less at n ("n" is a positive integer equal to or greater than "2") different frequencies within a preset frequency range, and the load power factor and load impedance of the composite resonant circuit due to the short-time operation are measured, and the measured load power factor and load impedance are compared with their respective thresholds. Based on the comparison results, an output frequency is selected.

[0022] Furthermore, the control method for a wireless power supply inverter according to the present invention is the above-described control method for a wireless power supply inverter according to the present invention, wherein the inverter is operated for a first short time (m=1) at a frequency in a frequency band near the middle of the above-described preset frequency range.

[0023] Furthermore, a control method for a wireless power supply inverter according to the present invention is the above-described control method for a wireless power supply inverter according to the present invention, wherein when the comparison result shows that the load power factor is equal to or greater than a threshold, a frequency at which the load power factor is equal to or greater than a threshold is selected as an output frequency, and when the comparison result shows that the load power factor is less than the threshold, a frequency at which the load impedance is equal to or greater than a threshold is selected as an output frequency.

[0024] Furthermore, a control method for a wireless power supply inverter according to the present invention is the above-described control method for a wireless power supply inverter according to the present invention, wherein when switching the frequency when operating for a short period of time of m times or less, the output of the inverter circuit is temporarily turned off before switching the frequency.

[0025] Furthermore, a control method for a wireless power supply inverter according to the present invention is the above-described control method for a wireless power supply inverter according to the present invention, wherein when switching the frequency during short-term operation of the inverter for m or fewer times, the output of the inverter circuit is not temporarily turned off, but the frequency is switched with the output of the inverter circuit lowered.

[0026] Furthermore, the wireless power feeder according to the present invention is a wireless power feeder including a wireless power feed inverter connected to a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit, wherein the wireless power feed inverter connected to the composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit is the wireless power feed inverter according to the present invention described above. [Effects of the Invention]

[0027] Since the present invention is configured as described above, it is possible to suppress deterioration of the load power factor of the composite resonant circuit connected to the wireless power supply inverter and improve the load power factor of the composite resonant circuit. It has the excellent effect of being able to do so. [Brief explanation of the drawings]

[0028] [Figure 1] FIG. 1 is a diagram illustrating the configuration of a wireless power supply device equipped with a fixed single frequency inverter, which is a conventionally known inverter for wireless power supply. [Figure 2] FIG. 2 is a diagram illustrating the configuration of a wireless power feeder including a power factor correction frequency selective inverter, which is a wireless power feed inverter according to an example of an embodiment of the present invention. [Figure 3] FIG. 3 is a diagram illustrating an example of the configuration of the power factor correction frequency selective inverter shown in FIG. [Figure 4] FIG. 4 is a diagram illustrating the configuration of a wireless power supply device, showing an example in which the control unit of the power factor correction frequency selective inverter shown in FIG. 3 is configured as a circuit. [Figure 5]FIG. 5 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, and is a graph showing an example when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.087." [Figure 6] FIG. 6 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, and is a graph showing an example when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.145." [Figure 7] FIG. 7 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, and is a graph showing an example when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.229." [Figure 8] FIG. 8 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, and is a graph showing an example when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.3." [Figure 9] FIG. 9 is a graph showing an example of the characteristics of the load power factor and the load impedance of the complex resonance circuit when the wireless power feeder shown in FIG. 1 is operated at a frequency of 85 kHz. [Figure 10] FIG. 10 is a diagram showing an example of a table used when selecting an output frequency during power supply operation in the wireless power supply device shown in FIG. [Figure 11] FIG. 11 is a graph showing an example of the load power factor and output characteristics with respect to the coupling coefficient in the wireless power feeder shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0029] Hereinafter, an example of an embodiment of a wireless power supply inverter, a control method for a wireless power supply inverter, and a wireless power supply device according to the present invention will be described in detail with reference to the accompanying drawings.

[0030] In the following description of the "Mode for Carrying Out the Invention" section, the same or corresponding configurations and functions as those described with reference to FIG. 1 will be denoted by the same reference numerals as those used in FIG. 1, and detailed description of those configurations and functions will be omitted.

[0031] (I) Description of the configuration and operation of a wireless power supply inverter and a wireless power supply device according to an example of an embodiment of the present invention FIG. 2 is a diagram illustrating the configuration of a wireless power feeder including a power factor correct frequency selective inverter, which is a wireless power feed inverter according to an embodiment of the present invention.

[0032] FIG. 3 is a diagram illustrating an example of the configuration of the power factor correction frequency selective inverter shown in FIG.

[0033] Furthermore, FIG. 4 shows a configuration explanatory diagram of a wireless power supply device showing an example in which the control unit of the power factor correction frequency selective inverter shown in FIG. 3 is configured as a circuit.

[0034] A wireless power feeder 10 according to an example of the embodiment of the present invention differs from a conventional wireless power feeder 100 in that it includes a wireless power feeder inverter 12 according to the present invention (for ease of explanation, the wireless power feeder inverter according to the present invention will be referred to as a “power factor corrected frequency selective inverter”) instead of a fixed single frequency inverter 106.

[0035] Unlike the fixed single frequency inverter 106, this power factor correction frequency selection inverter 12 is an inverter capable of varying the output frequency, and is configured to include an inverter circuit 12a that is connected between the converter 104 and the complex resonant circuit 108 to perform inverter operation, and a control unit 12b that controls the inverter circuit 12a.

[0036] The control unit 12b, in the wireless power supply device 10 including the composite resonant circuit 108 connected to the power factor correction frequency selective inverter 12, controls the inverter circuit 12a to operate for short periods of time m ("m" is a positive integer of 2 or more) or less times at n ("n" is a positive integer of 2 or more) different output frequencies within a preset frequency range, measures two values, namely, the load power factor and the load impedance of the composite resonant circuit 108 connected to the power factor correction frequency selective inverter 12 during the short-time operation to obtain each measurement value, compares the two obtained measurement values ​​with threshold values ​​for each measurement value, thereby selecting an output frequency that improves the load power factor of the composite resonant circuit 108, determines the selected output frequency as the output frequency when the power factor correction frequency selective inverter 12 performs power supply operation, and controls the inverter circuit 12a to operate at the determined output frequency to supply power to the battery 112.

[0037] Here, the above-mentioned preset frequency range may be determined, for example, according to the standard to which the wireless power feeder 10 conforms. For example, in accordance with the SAE standard, the preset frequency range is "79 kHz to 90 kHz."

[0038] Furthermore, the control unit 12b operates the inverter circuit 12a for a short period of time, m times or less. This "m times" is the number of times required to select and determine an output frequency that can improve load efficiency, and since the fewer the "m times" is, the shorter the processing time can be, it is preferable to operate the inverter circuit 12a for a short period of time, m times or less.

[0039] Furthermore, the control unit 12b operates the inverter circuit 12a for a short time of m times or less, but this "short time operation" is not intended to supply power to the battery 112, but rather refers to the shortest time required to measure two values, the load power factor and the load impedance of the composite resonant circuit 108.

[0040] Furthermore, the process of comparing the two measured values ​​of the load power factor and the load impedance of the composite resonant circuit 108 with the threshold values ​​of each measured value and selecting an output frequency that improves the load power factor of the composite resonant circuit 108 will be described in detail later.

[0041] The threshold value of the load power factor and the threshold value of the load impedance are preset arbitrary values. If the wireless power feeder 10 complies with the SAE standard, the threshold value of the load power factor may be set to, for example, "0.7," and the threshold value of the load impedance may be set to, for example, "13 Ω."

[0042] The control unit 12b can be constructed, for example, by a circuit configuration as shown in FIG.

[0043] Hereinafter, with reference to FIG. 4, we will explain how to construct the control unit 12b using a circuit configuration. The numbers (1) to (7) in FIG. 4 indicate the order of operations, meaning that the operations proceed in ascending order from (1) to (7).

[0044] The control unit 12b is configured to include a DC power detection unit 122 connected to the DC power detector 14 arranged between the converter 104 and the inverter circuit 12a, an output voltage detection unit 124 connected to the output voltage detector 16, an output current detection unit 126 connected to the output current detector 18, a divider 128 connected to the output voltage detection unit 124 and the output current detection unit 126, a multiplier 130 connected to the output voltage detection unit 124 and the output current detection unit 126, a divider 132 connected to the DC power detection unit 122 and the multiplier 130, a power factor acquisition unit 134 connected to the divider 132, an impedance acquisition unit 136 connected to the divider 128, a power factor threshold comparison and determination circuit 138 connected to the power factor acquisition unit 134, an impedance threshold comparison and frequency determination circuit 140 connected to the impedance acquisition unit 136, a continuous power supply instruction unit 142, and an m-th frequency setting unit 144.

[0045] In the control unit 12b, first, the mth frequency setting unit 144 is set to an initial value of "m=1", and the inverter circuit 12a is operated for a short time with one of n frequencies within a preset frequency range as the output frequency.

[0046] The output voltage V and output current I of the inverter circuit 12a during this short-time operation are detected by an output voltage detector 124 and an output current detector 126, respectively, and an impedance Z (Z=V / I) is calculated by a divider 128.

[0047] At the same time, the output voltage V and output current I of the inverter circuit 12a are detected by an output voltage detection unit 124 and an output current detection unit 126, respectively, and a multiplier 130 calculates "V×I." A divider 132 calculates a power factor (power factor=P / (V×I)) using the DC power P of the input stage of the inverter circuit 12a detected by the DC power detection unit 122 and "V×I."

[0048] Here, the inverter output has a high-frequency distorted waveform, which makes measurement accuracy poor. For this reason, when calculating the power factor, the DC power at the input stage of the inverter circuit is generally used as the inverter output power, since the inverter loss is small.

[0049] The power factor calculated by the divider 132 is acquired by the power factor acquisition unit 134 as a determination target in the power factor threshold comparison and determination circuit 138 , and is input to the power factor threshold comparison and determination circuit 138 .

[0050] The operations of the power factor threshold comparison and determination circuit 138 and the impedance threshold comparison and frequency determination circuit 140 will be described in detail later, but will be outlined below.

[0051] That is, the power factor threshold comparison and determination circuit 138 compares the input power factor with the threshold, and if it is determined that the input power factor is equal to or greater than the threshold (power factor OK), the continuous power supply instruction unit 142 operates the inverter circuit 12a with the frequency at which the inverter circuit 12a was operated for a short time as described above as the output frequency, and controls so as to continuously supply power to the battery 112.

[0052] On the other hand, if the power factor threshold comparison and determination circuit 138 determines that the input power factor is less than the threshold (power factor NG), the impedance threshold comparison and frequency determination circuit 140 compares the input impedance with the threshold.

[0053] That is, the impedance threshold comparison / frequency determination circuit 140 compares the input impedance with a threshold, and if it is determined that the input impedance is equal to or greater than the threshold (impedance OK), the continuous power supply instruction unit 142 operates the inverter circuit 12a with the frequency at which the inverter circuit 12a was operated for a short time as described above as the output frequency, thereby controlling continuous power supply to the battery 112.

[0054] On the other hand, if the impedance threshold comparison / frequency determination circuit 140 determines that the input impedance is less than the threshold (impedance NG), the m-th frequency setting unit 144 is set to "m=2", and the inverter circuit 12a is operated for a short time with any one of the n frequencies in the preset frequency range other than the frequency used when "m=1" as the output frequency, and the above operation is repeated while incrementing m by "1" and selecting n different frequencies.

[0055] (II) Description of an example of operation of a wireless power supply inverter and a wireless power supply device according to an embodiment of the present invention FIG. 5 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, and shows an example of a graph when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.087."

[0056] FIG. 6 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in FIG. 1, in which the coupling coefficient k between the transmitting resonant circuit and the receiving resonant circuit is "0.145."

[0057] Furthermore, Figure 7 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor correction frequency selective inverter of the wireless power feeder shown in Figure 1, and shows an example graph when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.229".

[0058] Furthermore, Figure 8 is a graph showing an example of the frequency characteristics of the load power factor and load impedance of a composite resonant circuit connected to the power factor improvement frequency selective inverter of the wireless power feeder shown in Figure 1, and shows an example graph when the coupling coefficient k between the power transmitting resonant circuit and the power receiving resonant circuit is "0.3".

[0059] FIG. 9 shows a graph illustrating an example of the characteristics of the load power factor and the load impedance of the complex resonance circuit when the wireless power feeder shown in FIG. 1 is operated at a frequency of 85 kHz.

[0060] 1. Furthermore, FIG. 10 shows a diagram illustrating an example of a table used when selecting an output frequency during power supply operation in the wireless power supply device shown in FIG.

[0061] Here, as described above, the coupling coefficient k is a constant determined by the distance L, which is the clearance between the power transmitting resonant circuit 108a and the power receiving resonant circuit 108b that constitute the composite resonant circuit 108, i.e., the clearance between the power transmitting coil and the power receiving coil. In the examples shown in Figures 5 to 8, the coupling coefficient is in the range used by a typical EV.

[0062] 5 to 8, the solid line indicates the load power factor, and the broken line indicates the load impedance.

[0063] As explained above with reference to FIG. 4, the inverter output power P (W), output voltage V (Vrms), and output current I (Arms) are measured, and the load impedance (Z) is calculated as follows: Load power factor=P / (V×A) can be obtained by calculation.

[0064] Next, a description will be given of the processing relating to the frequency determination method executed by the power factor threshold comparison and determination circuit 138 and the impedance threshold comparison and frequency determination circuit 140.

[0065] To facilitate understanding of the present invention, in this wireless power supply device 10, the preset frequency range is set to "79 kHz to 90 kHz", and three frequencies, "81 kHz", "85 kHz", and "88 kHz", are set as selectable frequencies with "n=3".

[0066] First, the first wireless power transfer is performed in a short time at 85 kHz with "m=1", and the inverter output power P, output voltage V, and output current I are measured, and the load power factor and load impedance Z are calculated (see Figure 9), and compared with their respective threshold values.

[0067] In this embodiment, the threshold value of the load power factor is set to "0.7" and the threshold value of the load impedance Z is set to "13Ω".

[0068] Here, a frequency that improves the load power factor can be selected based on the table shown in FIG.

[0069] That is, when the first wireless power supply is performed in a short time at 85 kHz with "m=1", if the load power factor is equal to or greater than the threshold value of 0.7 in the table shown in FIG. 10, 85 kHz is selected as the output frequency and the power supply operation is performed.

[0070] On the other hand, when the first wireless power supply is performed in a short time at 85 kHz with "m=1", even if the load power factor is less than the threshold value of 0.7, if the load impedance value is equal to or greater than the threshold value of 13 Ω in the table shown in FIG. 10, 85 kHz is selected as the output frequency and the power supply operation is performed.

[0071] In the above process, that is, when the first wireless power supply is performed in a short time at 85 kHz with "m=1", if it is not possible to select an output frequency and perform the power supply operation, the second wireless power supply is performed in a short time at 81 kHz with "m=2", and the same process as above is performed.

[0072] Furthermore, when the second wireless power supply is performed in a short time at 81 kHz with "m=2", if it is not possible to select an output frequency to perform the power supply operation, the third wireless power supply is performed in a short time at 88 kHz with "m=3", and the same processing as described above is performed.

[0073] If the output frequency cannot be selected by the above process and power supply operation cannot be performed, an operation error is detected and the process is terminated.

[0074] That is, if a load power factor equal to or greater than the threshold value is measured during short-time power supply to the inverter circuit 12a, the frequency used during that short-time power supply is selected as the output frequency to continue power supply, while if a load power factor less than the threshold value is measured during that short-time power supply, the output frequency is determined based on the measured value of the load impedance and power is supplied. In this way, priority is given to the load power factor when selecting the output frequency.

[0075] As shown in FIG. 11, it can be seen that even if the coupling coefficient changes, the load power factor is improved at the selected frequency, and the output is also improved.

[0076] (III) Description of the Functions and Effects of the Wireless Power Supply Inverter and Wireless Power Supply Device According to an Example of an Embodiment of the Present Invention As described above, in the wireless power supply device 10, the composite resonant circuit 108 is connected to the power factor correction frequency selection inverter 12. Therefore, n fixed frequencies are set within a preset frequency range, and power is supplied for a short period of time m times or less for each of the n fixed frequencies to measure two values, namely, the load power factor and the load impedance of the composite resonant circuit 108, and the two measured values ​​are compared with the respective threshold values, thereby selecting and determining a frequency that improves the load power factor as the output frequency.

[0077] That is, by first performing short-term power supply for m or less times without the purpose of power supply operation, a frequency at which the load power factor is improved can be selected as the output frequency, thereby improving the load power factor and enabling actual power supply operation.

[0078] In addition, in an operating region where the load power factor is good, it is possible to reduce the output current for the same output power, which makes it possible to reduce output noise and downsize the inverter circuit.

[0079] (IV) Description of other embodiments and modifications It should be noted that the above-described embodiment is merely an example, and the present invention can be embodied in various other forms. In other words, the present invention is not limited to the above-described embodiment, and various omissions, substitutions, and modifications can be made without departing from the spirit of the present invention.

[0080] For example, the above-described embodiment may be modified as shown in the following (IV-1) to (IV-6).

[0081] (IV-1) In the above-described embodiment, n different fixed frequencies are set within a predetermined frequency range, and the device is operated for a short time of m times or less at each of the n different fixed frequencies. Here, when setting the above-described frequency range, it is usually set so that a frequency with a high probability of improving the load power factor is located in a frequency band near the middle of the frequency range. For this reason, for example, a first short-time power supply (m = 1) is performed at a frequency in a frequency band near the middle of the predetermined frequency range, for example, a frequency located in the middle of the frequency range, and two values, the load power factor and the load impedance of the composite resonant circuit 108, are measured. By comparing the two measured values ​​with the respective thresholds, it becomes possible to determine a frequency that efficiently improves the load power factor as the output frequency.

[0082] (IV-2) Although detailed explanation is omitted in the above-described embodiment, when switching the frequency when short-term power supply is performed m times or less, the output of the inverter circuit 12a may be temporarily turned off and then switched to another frequency for short-term operation.

[0083] (IV-3) Although detailed explanation is omitted in the above-described embodiment, when switching the frequency when short-term power supply is performed m times or less, the output of the inverter circuit 12a may not be temporarily turned off, but the output of the inverter circuit 12a may be reduced and the frequency may be switched to another frequency for short-term operation.

[0084] (IV-4) In the above embodiment, the control unit 12b is constructed using the circuit configuration shown in FIG. 4. However, the configuration of the control unit 12b is not limited to this, and it may be realized using a circuit configuration other than the circuit configuration shown in FIG.

[0085] (IV-5) In the above embodiment, the control unit 12b is configured with the circuit configuration shown in FIG. 4, but the control unit 12b may also be configured with a computer system such as a microcomputer.

[0086] (IV-6) Of course, the above-described embodiments and the embodiments shown in (IV-1) to (IV-5) above may be combined as appropriate. [Industrial Applicability]

[0087] The present invention can be used in a wireless power supply inverter device, which is a power supply device to which a complex resonant circuit is connected, and a wireless power supply device. [Explanation of symbols]

[0088] 10. Wireless power supply device according to the present invention 12 Wireless power supply inverter according to the present invention (power factor correction frequency selective inverter) 12a Inverter circuit 12b control section (control means) 14 DC power detector 16 Output voltage detector 18 Output current detector 100 Conventional wireless power supply device 102 Alternating current (AC) power supply 104 Converter 106 Conventional wireless power inverter (fixed single frequency inverter) 108 Complex resonant circuit 108a Power transmission resonant circuit (power transmission coil) 108b Receiving resonance circuit (receiving coil) 110 Rectifier circuit 112 Battery 122 DC power detection unit 124 Output voltage detector 126 Output current detector 128 divider 130 Multiplier 132 Divider 134 Power factor acquisition section 136 Impedance acquisition unit 138 Power factor threshold comparison circuit 140 Impedance threshold comparison and frequency determination circuit 142 Continuous power supply instruction unit 144 mth frequency setting unit L: Distance between the transmitting and receiving coils k Coupling coefficient k determined by distance L

Claims

1. In a wireless power inverter, a complex resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit is connected and used, an inverter circuit to which a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit is connected; a control means for controlling the operation of the inverter circuit; and The control means operates the inverter circuit for short periods of time m ("m" is a positive integer, provided that "m≦n") or less times at n ("n" is a positive integer equal to or greater than "2") different frequencies within a preset frequency range, measures the load power factor and load impedance of the complex resonant circuit during the short-term operation, and selects an output frequency based on a comparison result obtained by comparing the measured load power factor and load impedance with respective threshold values. A wireless power supply inverter characterized by:

2. The wireless power supply inverter according to claim 1, The first (m=1) short-time operation is performed at a frequency in a frequency band near the middle of the preset frequency range. A wireless power supply inverter characterized by:

3. The wireless power supply inverter according to claim 1, When the comparison result indicates that the load power factor is equal to or greater than a threshold value, a frequency at which the load power factor is equal to or greater than a threshold value is selected as an output frequency; When the comparison result indicates that the load power factor is less than a threshold value, a frequency at which the load impedance is equal to or greater than a threshold value is selected as an output frequency. A wireless power supply inverter characterized by:

4. The wireless power supply inverter according to claim 1, 2 or 3, When switching the frequency when operating for a short period of time not more than m times, the output of the inverter circuit is turned off once and then the frequency is switched. A wireless power supply inverter characterized by:

5. The wireless power supply inverter according to claim 1, 2 or 3, When switching the frequency during the short-time operation of the inverter circuit not more than m times, the frequency is switched with the output of the inverter circuit lowered without temporarily turning off the output of the inverter circuit. A wireless power supply inverter characterized by:

6. A method for controlling a wireless power supply inverter using a composite resonant circuit including a power transmitting resonant circuit and a power receiving resonant circuit, The inverter circuit is operated for a short time period of m ("m" is a positive integer of 2 or more) or less times at n ("n" is a positive integer of 2 or more) different frequencies within a preset frequency range, the load power factor and load impedance of the complex resonant circuit are measured by the short-time operation, and the measured load power factor and load impedance are compared with respective threshold values, and an output frequency is selected based on the comparison result. A method for controlling a wireless power supply inverter.

7. 7. The method for controlling a wireless power supply inverter according to claim 6, The first (m=1) short-time operation is performed at a frequency in a frequency band near the middle of the preset frequency range. A method for controlling a wireless power supply inverter.

8. 7. The method for controlling a wireless power supply inverter according to claim 6, When the comparison result indicates that the load power factor is equal to or greater than a threshold value, a frequency at which the load power factor is equal to or greater than a threshold value is selected as an output frequency; When the comparison result indicates that the load power factor is less than a threshold value, a frequency at which the load impedance is equal to or greater than a threshold value is selected as an output frequency. A method for controlling a wireless power supply inverter.

9. 9. The method for controlling a wireless power supply inverter according to claim 6, 7, or 8, When switching the frequency when operating for a short period of time not more than m times, the output of the inverter circuit is turned off once and then the frequency is switched. A method for controlling a wireless power supply inverter.

10. 9. The method for controlling a wireless power supply inverter according to claim 6, 7, or 8, When switching the frequency during the short-time operation of the inverter circuit not more than m times, the frequency is switched with the output of the inverter circuit lowered without temporarily turning off the output of the inverter circuit. A method for controlling a wireless power supply inverter.

11. A wireless power supply device including a wireless power supply inverter connected to a complex resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit, The wireless power supply inverter used by connecting a complex resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit is the wireless power supply inverter according to any one of claims 1, 2 and 3. A wireless power supply device characterized by:

12. A wireless power supply device including a wireless power supply inverter connected to a complex resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit, The wireless power supply inverter using a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit connected thereto is the wireless power supply inverter according to claim 4. A wireless power supply device characterized by:

13. A wireless power supply device including a wireless power supply inverter connected to a complex resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit, The wireless power supply inverter using a composite resonant circuit having a power transmitting resonant circuit and a power receiving resonant circuit connected thereto is the wireless power supply inverter according to claim 5. A wireless power supply device characterized by:

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