Abstract:
A non-contact power supply apparatus is configured to transmit power in a non-contact manner from a primary-side coil to a secondary-side coil by supplying alternating current power to the primary-side coil. The non-contact power supply apparatus is provided with an alternating current power output unit, a power transmitting unit, wiring, a detecting unit, and a determining unit. The alternating current power output unit is capable of outputting alternating current power. The power transmitting unit has the primary-side coil. The wiring electrically connects the alternating current power output unit and the power transmitting unit to each other. The detecting unit detects a ratio between an output voltage and an output current, which are outputted from the alternating current power output unit, or a phase difference between the output voltage and the output current. On the basis of the ratio and/or the phase difference detected by means of the detecting unit, the determining unit determines whether an abnormality has generated or not in the non-contact power supply apparatus.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is the National Stage of International Application No. PCT/JP2012/080083 filed Nov. 20, 2012, which claims the benefit of Japanese Application No. 2011-256734, filed Nov. 24, 2011, the disclosures of which are incorporated herein by reference in their entireties. 
     TECHNICAL FIELD 
     The present invention relates to a non-contact power supplying apparatus and a non-contact power supplying system. 
     BACKGROUND ART 
     Patent document 1 and non-patent document 1 each describe a known example of a non-contact power supplying apparatus capable of transmitting power in a non-contact manner to an appliance subject to power supplying. Such a non-contact power supplying apparatus includes a high-frequency power supply and a transmission side resonance circuit, which includes a primary coil and a primary capacitor. In this case, when the transmission side resonance circuit (primary coil) is spaced apart by a predetermined distance from a reception side resonance circuit (secondary coil), which has the same resonance frequency as the transmission side resonance circuit, the input of high-frequency power from the high-frequency power supply to the transmission side resonance circuit causes magnetic field resonance that transmits some of the high-frequency power to the reception side resonance circuit. 
     PRIOR ART DOCUMENT 
     Patent Document 
     
         
         Patent Document 1: International Patent Publication No. WO/2007/008646A2 
       
    
     Non-Patent Document 
     
         
         Non-Patent Document 1: NIKKEI ELECTRONICS 2007.12.3 Pgs. 117-128 
       
    
     SUMMARY OF THE INVENTION 
     When an abnormality occurs in the non-contact power supplying apparatus for one reason or another, the transmission efficiency may be decreased. Thus, the non-contact power supplying apparatus needs to detect abnormalities in a preferable manner. The same applies to a non-contact power supplying apparatus that supplies power in a non-contact manner through electromagnetic induction. 
     It is an object of the present invention to provide a non-contact power supplying apparatus capable of detecting abnormalities in a preferable manner and a non-contact power supplying system using the non-contact power supplying apparatus. 
     To achieve the above object, one aspect of the present invention is a non-contact power supplying apparatus configured to supply a primary coil with AC power to transmit power in a non-contact manner from the primary coil to a secondary coil. The non-contact power supplying apparatus includes an AC power output unit, a power transmission unit, a cable, a detector, and a determination unit. The AC power output unit is capable of outputting AC power. The power transmission unit includes the primary coil. The cable electrically connects the AC power output unit and the power transmission unit. The detector detects a ratio of an output voltage and an output current output from the AC power output unit or a phase difference of the output voltage and the output current. The determination unit determines whether or not an abnormality is occurring in the non-contact power supplying apparatus based on at least one of the ratio and the phase difference detected by the detector. 
     In the above configuration, changes in the resistance or inductance of an AC power transmission system including the AC power output unit, the power transmission unit, and the cable are detected as the ratio of the output voltage and the output current or the phase difference of the output voltage and the output current. The determination, of whether or not an abnormality is occurring based on the detection result of the detector allows for detection of an abnormality in the AC power transmission system such as an abnormality in the power transmission unit like deformation of the primary coil and an abnormality in the cable, or an abnormality in the AC power output unit. In particular, the output voltage and the output current are detected relatively easily. Thus, an abnormality may be detected in the non-contact power supplying apparatus with a relatively simple configuration. 
     Preferably, each of the primary coil, and the cable includes bundled conductive wires. The determination unit determines from at least one of the ratio and the phase difference whether or not at least one of the primary coil and the cable is partially broken or determines from the phase difference whether or not the primary coil is deformed. 
     In the above configuration, the formation of the primary coil and the cable with conductive wires limits energy losses caused by the skin effect that may occur when using AC power. In this case, the primary coil and the cable may be partially broken in which some of the conductive wires break or the primary coil may be deformed. In particular, when the distance changes between the primary coil and the secondary coil, the change lowers the power transmission efficiency and the primary coil and the cable covert the AC power to heat. The heat may easily cause partial wire breakage such as that described above. 
     In this regard, to determine whether or not an abnormality is occurring, the above configuration uses the ratio of the output voltage and the output current or the phase difference of the output voltage and the output current to detect a change in the resistance based on a partial wire breakage or a change in the inductance based on deformation of the primary coil. Thus, an abnormality such as a partial wire breakage or deformation of the primary coil may be detected in a suitable manner. 
     Preferably, the determination unit determines that at least one of the primary coil and the cable is partially broken when the ratio of the output current to the output voltage is a value other than zero and lower than a threshold set in advance. 
     Preferably, the determination unit determines that at least one of the primary coil and the cable is partially broken when the phase difference is in a specified range. 
     Preferably, the determination unit determines that the primary coil is deformed when the ratio of the output current to the output voltage is a value other than zero and higher than a threshold set in advance. 
     Preferably, the determination unit determines that the primary coil is deformed when the phase difference is outside a specified range set in advance. 
     Preferably, the non-contact power supplying apparatus further includes a control unit that controls the AC power output unit so that AC power for determining an abnormality is output when the secondary coil is not located at a position where power is receivable from the primary coil. The determination unit performs the determination based on the detection result of the detector when the AC power for determining an abnormality is output. 
     The above configuration allows for determination of whether or not the non-contact power supplying apparatus includes an abnormality before starting power supplying. Thus, an abnormality in the non-contact power supplying apparatus may be recognized at a relatively early stage. This allows for repairs and replacements to be readily performed. 
     Further, when the secondary coil is not arranged at the position where power is receivable from the primary coil, the mutual effect of the primary coil and the secondary coil has a small influence on abnormality determination. Thus, there is no need to consider the influence of the mutual effect during abnormality determination. This allows for an improvement in the accuracy of the abnormality determination and allows for the non-contact power supplying apparatus to be specified as being abnormal when an abnormality is determined during an abnormality determination. 
     Preferably, a non-contact power supplying system is provided including the non-contact power supplying apparatus of the above aspect. The non-contact power supplying system transmits the AC power to the secondary coil that is arranged in a vehicle and charges a vehicle battery arranged in the vehicle with the AC power received by the secondary coil. 
     In comparison with a battery for a cellular phone, a vehicle battery is required to have a large capacitance. Thus, it may be expected that a relatively large amount of power is involved in a vehicle non-contact power supplying apparatus for a non-contact power supplying system that charges a vehicle battery. Further, the relative position of the vehicle and the vehicle non-contact power supplying apparatus easily changes in accordance with the parking position of the vehicle. Thus, energy losses easily generate heat in the primary coil and the cable. Further, it may be assumed that a person or a vehicle, which is heavier than a person, will be arranged on the primary coil or cable of the vehicle non-contact power supplying apparatus. Thus, there is a tendency of a relatively large load being applied to the primary coil and the cable. Accordingly, in the vehicle non-contact power supplying apparatus, an abnormality such as a partial breakage or deformation of the primary coil may occur. 
     In this regard, the above configuration allows for early detection of an abnormality such as a partial damage or deformation of the primary coil in the vehicle non-contact power supplying apparatus. This provides a vehicle non-contact power supplying system that allows for an abnormality to be detected in a preferable manner when charging a vehicle battery with the vehicle non-contact power supplying apparatus. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The FIGURE is a block circuit diagram showing the electric configuration of a non-contact power supplying system using a non-contact power supplying apparatus according to one embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     One embodiment of the present invention will now be described with reference to the FIGURE . 
     As shown in the FIGURE , a non-contact power supplying system S, which performs power transmission or charging in a non-contact manner, includes a non-contact power supplying apparatus  10 , which is arranged on the ground, and an onboard apparatus  20 , which is arranged in a vehicle. 
     The non-contact power supplying apparatus  10  is configured to be capable of supplying power in a non-contact manner to the onboard apparatus  20 . In detail, the non-contact power supplying apparatus  10  includes a high-frequency power supply  11  as an AC power supply connected to an external power supply such as a commercial power supply. The high-frequency power supply  11  includes a power supply main circuit  12  as an AC power output unit. The power supply main circuit  12  is configured to convert power input from an external power supply to high-frequency power having a predetermined frequency and is capable of, outputting the converted high-frequency power as an AC power. 
     The non-contact power supplying apparatus  10  includes a power transmission circuit  13  as a power transmission unit that transmits power in a non-contact manner to the onboard apparatus  20 . A cable  14 , which is formed by a Litz wire, electrically connects the power transmission circuit  13  to the power supply main circuit  12 . A Litz wire is a bundle of conductive wires, e.g., copper wires). The power transmission circuit  13  includes a primary coil  13   a , which is formed by a Litz wire, and a primary capacitor  13   b , which is connected in parallel to the primary coil  13   a . The power transmission circuit  13  resonates when receiving high-frequency power. 
     The onboard apparatus  20  includes a power reception circuit  21  as a power reception unit. The power reception circuit  21  is configured so that magnetic field resonance may occur with the power transmission circuit  13 . In detail, like the power transmission circuit  13 , the power reception circuit  21  includes a secondary coil  21   a  and a secondary capacitor  21   b  that are connected to each other in parallel. The power reception circuit  21  and the power transmission circuit  13  are set to have the same resonance frequency. Thus, when the power transmission circuit  13  receives high-frequency power, magnetic field resonance occurs in the power transmission circuit  13  and the power reception circuit  21 , and power is transmitted from the power transmission circuit  13  to the power reception circuit  21 , that is the power is transmitted from the primary coil  13   a  to the secondary coil  21   a.    
     The onboard apparatus  20  includes a rectifier  22  and a vehicle battery  23 . The rectifier  22  rectifies the high-frequency power received by the power reception circuit  21 . The vehicle battery  23  is electrically connected to the rectifier  22 . The DC power rectified by the rectifier  22  is input to the vehicle battery  23 . This charges the vehicle battery  23 . 
     The non-contact power supplying apparatus  10  includes a power supply controller  15 , which serves as a control unit that controls the power supply main circuit  12 . The onboard apparatus  20  includes a vehicle controller  24  that controls the charging of the vehicle battery  23 . The vehicle controller  24  is configured to be capable of recognizing the state of charge of the vehicle battery  23 . Each of the controllers  15  and  24  are configured to be capable of performing wireless communication with each other so that information can be transferred between the two. 
     When the vehicle is arranged at a chargeable position, which is a power transmittable position, more specifically, at a position allowing for magnetic field resonance to occur between the power transmission circuit  13  and the power reception circuit  21 , that is between the primary coil  13   a  and the secondary coil  21   a , the vehicle controller  24  transmits a charge enablement signal to the power supply controller  15 . When the power supply controller  15  receives the charge enablement signal, the power supply controller  15  controls the power supply main circuit  12  so that the power supply main circuit  12  outputs high-frequency power. In detail, the power supply controller  15  exchanges signals with the vehicle controller  24  to determine whether or not the power transmission circuit  13  and the power reception circuit  21  are located at positions allowing for power transmission, that is, whether or not the vehicle exists. Then, the power supply controller  15  controls the power supply main circuit  12  based on the determination. 
     When the charging of the vehicle battery  23  is completed, the vehicle controller  24  transmits a charge completion signal, that is, a charge end signal to the power supply controller  15 . The power supply controller  15  controls the power supply main circuit  12  to stop the output of the high-frequency power when receiving the charge completion signal. 
     The occurrence of an abnormality in the primary coil  13   a  or the like of the non-contact power supplying apparatus  10  lowers the charging efficiency of the vehicle battery  23 . This may prolong the charging time or consume unnecessary′ power. 
     In this regard, the non-contact power supplying apparatus  10  includes a structure that periodically detects abnormalities. The structure will now be described. 
     The non-contact power supplying apparatus  10  includes a detection unit  16 . The detection unit  16  detects the output voltage that is output from the power supply main circuit  12 , the output current that is output from the power supply main circuit  12 , and the phase difference between the output voltage and the output current. The output voltage corresponds to a voltage applied to the power transmission circuit  13 . The output current corresponds to a current flowing through the power transmission circuit  13 . Then, the detection unit  16  outputs the detection result to the power supply controller  15 . 
     Based on the detection result of the detection unit  16 , the power supply controller  15  periodically determines whether or not an abnormality is occurring in the power transmission circuit  13  or the cable  14 . Accordingly, the power supply controller  15  functions as a determination unit that determines whether or not an abnormality is occurring in the power transmission circuit  13  or the cable  14 . More specifically, the power supply controller  15  first determines whether or not communication can be established with the vehicle controller  24  in a cycle that is set in advance. 
     The maximum distance in which the controllers  15  and  24  are capable of communicating with each other is set in advance. The maximum distance is a distance greater than the distance between the controllers  15  and  24  when the vehicle is located at a chargeable position, that is, when the coils  13   a  and  21   a  are located at positions allowing for the occurrence of magnetic field resonance. Thus, the determination of whether or not communication can be established with the vehicle controller  24  is equivalent to a determination of whether or not the vehicle is located at a chargeable position, that is whether or not the secondary coil  21   a  is located at a position where power may be received from the primary coil  13   a.    
     When communication cannot be established, this indicates that the vehicle does not exist at the chargeable position. In this case, the power supply controller  15  controls the power supply main circuit  12  to output high-frequency power for abnormality determination, which is lower than the high-frequency power, over a predetermined period. The detection unit  15  detects the output voltage and output current of the power supply main circuit  12  and the phase difference of the output voltage and current. Then, the detection unit  16  outputs the detection result to the power supply controller  15 . 
     The high-frequency power used for abnormality determination may be supplied in any amount as long as the frequency is the same as the high-frequency power used for charging. For example, the amount of the high-frequency power used for abnormality determination may be the same as the high-frequency power used for charging. 
     The power supply controller  15  determines whether or not an abnormality is occurring based on the detection result. In detail, the power supply controller  15  calculates the ratio of the output current relative to the output voltage and determines whether or not the calculated ratio is a value other than “0” and is lower than a threshold, which is set in advance. The threshold is a ratio that is lower by an amount set in advance than the ratio of the output current relative to the output voltage when the abnormality determination high-frequency power is output under a situation in which the power transmission circuit  13  and the cable  14  do not include an abnormality, that is an initial state, and there are no items such as metal magnetically coupled to the power transmission circuit  13  near the power transmission circuit  13  in other words, the threshold is the lower limit value of a range that can be considered as normal operation. 
     When the calculated ratio is a value other than “0” and is lower than the threshold, the power supply controller  15  uses an indicator  17 , which is connected to the power supply controller  15 , to indicate that there is an abnormality. The indicator  17  is formed by, for example, a light emitting unit that emits light when indicating an abnormality. However, as long as an abnormality can be indicated, the indicator  17  may have any form. For example, the indicator  17  may have a structure that generates a sound or a structure using a display that shows characters of the like to indicate an abnormality. 
     The power supply controller  15  determines whether or not the phase difference between the output voltage and the output current is in a specified range, which is set in advance. When the detected phase difference is outside the specified range, the power supply controller  15  uses the indicator  17  to indicate an abnormality. The specified range includes phase differences for when the abnormality determination high-frequency power is output under a situation in which there is no abnormality in the power transmission circuit  13  and there is no item near the power transmission circuit  13  that is magnetically coupled to the power transmission circuit  13 . 
     The function of the detection unit  16  for detecting the output voltage and the output current and the function of the power supply controller  15  for calculating the ratio correspond to a function of a detector that detects the ratio of the output voltage and the output current that are output from the AC power output unit. 
     The operation of the non-contact power supplying apparatus of the present embodiment will now be described. 
     When a partial wire breakage occurs in the primary coil  13   a  or the cable  14  etc., it may be assumed that the resistance will increase at the location of the partial wire breakage. When the primary coil  13   a  is deformed, depending on the deformation, the resistance of the primary coil  13   a  may be increased. Thus, when a partial wire breakage or deformation of the primary coil  13   a  occurs, the resistance (load) as viewed from the high-frequency power supply  11  may increase. An increase in the resistance decreases the ratio of the output current to the output voltage. Thus, the determination of the comparison of the ratio and the threshold is equivalent to the abnormality determination of whether a partial wire breakage is occurring in the primary coil  13   a  or the cable  14  etc. or whether the primary coil  13   a  is deformed. 
     A partial wire breakage refers to a condition in which there is electrical connection but a wire breakage in a certain portion increases the resistance at that portion. More specifically, a partial wire breakage refers to a condition in which some of the bundled conductive wires in the cable  14  and the primary coil  13   a  are broken. 
     When the calculated ratio is “0”, there is a high probability of a complete wire breakage and not a partial wire breakage, that is, there is a high probability of no electric connection. Thus, when performing an abnormality determination with the above ratio, a complete wire breakage may be distinguished from a partial wire breakage by using the factor that the calculated ratio is a value other than “0” as a condition. 
     When the primary coil  13   a  is deformed, it may be assumed that the inductance of the primary coil  13   a  has changed. A change in the inductance changes the phase difference of the output voltage and the output current. Thus, the determination of whether or not the phase difference is in the specified range is equivalent to an abnormality determination of whether or not the primary coil  13   a  is deformed. 
     The power supply controller  15  is configured to perform the abnormality determination when the vehicle is not located at the chargeable position. This allows for the abnormality determination to be performed on the non-contact power supplying apparatus  10  before starting the charging of the vehicle. Accordingly, the charging is not started when there is an abnormality in the non-contact power supplying apparatus  10 . 
     A situation in which the vehicle is not located at the chargeable position is equivalent to a situation in which the onboard apparatus  20  and the non-contact power supplying apparatus  10  are separated from each other such that power cannot be transmitted between the two, more specifically, a situation in which the primary coil  13   a  and the secondary coil  21   a  are separated by a distance in which magnetic field resonance substantially does not occur between the primary coil  13   a  and the secondary coil  21   a . Thus, when performing abnormality determination, there is no need to take into consideration factors resulting from the mutual effect of the primary side, that is the non-contact power supplying apparatus  10 , and the secondary side, that is the onboard apparatus  20 ), such as a change in the inductance or a change in the output current caused by a change in the distance between the primary coil  13   a  and the secondary coil  21   a.    
     A partial wire breakage changes the resistance. However, the inductance does not easily change. Thus, under a situation in which the ratio of the output current to the output voltage is lower than the threshold, when the phase difference is in the specified range, there is a higher probability of a partial wire breakage than deformation of the primary coil  13   a . Under a situation in which the ratio of the output current to the output voltage is higher than the threshold, when the phase difference is outside the specified range, there is a higher probability of deformation of the primary coil  13   a  than a partial wire breakage. In this manner, the cause of an abnormality may be narrowed down by a certain extent by combining the abnormality determination result based on the ratio and the abnormality determination result based on the phase difference. 
     The present embodiment has the advantages described below. 
     (1) In the configuration that electrically connects the power supply main circuit  12  and the power transmission circuit  13  with the cable  14 , the detection unit  16  detects the output voltage that is output from the power supply main circuit  12 , the output current that is output from the power supply main circuit  12 , and the phase difference of the output voltage and the output current. An abnormality determination of whether or not an abnormality is occurring in at least one of the power transmission circuit  13  and the cable  14  is performed based on the detection result of the detection unit  16 . This allows for a change in the resistance or inductance of the power transmission circuit  13  and the cable  14  to be detected as the ratio of the output voltage and the output current or a phase difference of the output voltage and the output current. Further, by performing the abnormality determination based on the detection result, an abnormality in the power transmission circuit  13  such as deformation of the primary coil  13   a  and an abnormality in the non-contact power supplying apparatus  10  such as an abnormality in the cable  14  may be detected in a preferable manner. In particular, the detection unit  16  that detects the output voltage, the output current, and the phase difference is simpler than a configuration that detects impedance. Thus, an abnormality in the non-contact power supplying apparatus  10  may be detected in a preferable manner with a relatively simple structure. 
     (2) Since non-contact power supplying is performed through magnetic field resonance, there is a need to supply the first primary coil  13   a  and the cable  14  with high-frequency power. This may increase energy losses due to the skin effect. In this regard, the present embodiment forms the cable  14  and the primary coil  13   a  by bundling conductive wires to increase the surface area and limit increases in energy losses. In this case, a partial wire breakage may occur in which a wire breakage occurs in some of the conductive wires of the primary coil  13   a  or the cable  14 . Further, deformation of the primary coil  13   a  may occur. In particular, the vehicle non-contact power supplying apparatus  10  used in the non-contact power supplying system S that, charges the vehicle battery  23  involves a large amount of power as compared with a power supplying apparatus for a cellular phone or the like. Further, the distance between the primary coil  13   a  and the secondary coil  21   a  easily changes, and a change in the distance easily decreases the power transmission efficiency. In this case, the high-frequency power from the power supply main circuit  12  is easily converted to heat in the primary coil  13   a  and the cable  14 . Further, a person or a vehicle, which is heavier than a person, is arranged on the primary coil  13   a  and the cable  14  of the vehicle non-contact power supplying apparatus  10 . Thus, there is a tendency of a relatively large load being applied to the primary coil  13   a  and the cable  14 . Consequently, in the vehicle non-contact power supplying apparatus  10 , due to heat and load, partial wire breakage and deformation of the primary coil  13   a  tend to occur easily. 
     In this regard, the present embodiment allows for early detection of partial wire breakage and deformation of the primary coil  13   a  that may easily cause a problem in the vehicle non-contact power supplying apparatus  10 . Thus, the vehicle non-contact power supplying apparatus  10  allows for abnormality detection to be performed in a preferable manner. Further, by using the non-contact power supplying apparatus  10  to charge the vehicle battery  23 , the non-contact power supplying system S, that is the non-contact charger, may perform abnormality detection in a preferable manner. 
     (3) Abnormality determination is performed when the vehicle is not located at the chargeable position, more specifically, when the secondary coil  21   a  is not located at a position where power is receivable from the primary coil  13   a . This allows for determination of whether or not the non-contact power supplying apparatus  10  includes an abnormality before the charging is started. Thus, an abnormality in the non-contact power supplying apparatus  10  may be recognized at a relatively early stage. This allows for repairs and replacements to be readily performed. 
     Further, when the secondary coil  21   a  is not located at a position where power is receivable from the primary coil  13   a , the mutual effect of the primary coil  13   a  and the secondary coil  21   a  may be ignored. Thus, during abnormality determination, there is no need to consider such mutual effect, and there is no need to consider abnormalities in the onboard apparatus  20 . This increases the abnormality determination accuracy. Further, when an abnormality is determined during abnormality determination, the non-contact power supplying apparatus  10  may be specified as being abnormal. 
     (4) The abnormality determination is periodically performed when the vehicle is not located, at the chargeable position and there is no need for a user operation. Thus, an abnormality may be detected easily and quickly. 
     The above embodiment may be modified as follows. 
     The embodiment described magnetic field resonance type non-contact power supplying. Instead, the present invention may be applied to, for example, electromagnetic induction type non-contact power supplying. 
     In the embodiment, the cable  14  connects the power supply main circuit  12  and the power transmission circuit  13 . Instead, for example, the cable  14  may connect the power supply main circuit  12  with a coupling coil, and the coupling coil may be coupled through electromagnetic induction with the power transmission circuit  13 . In this case, by performing abnormality determination, an abnormality may be detected in the cable  14  and at least one of the coupling coil and the power transmission circuit  13 . In the above configuration, the coupling coil and the power transmission circuit  13  correspond to a power transmission unit. 
     The embodiment includes the primary capacitor  13   b  and the secondary capacitor  21   b . However, the primary capacitor  13   b  and the secondary capacitor  21   b  may be omitted. In this case, parasitic capacitance of the primary coil  13   a  and the secondary coil  21   a  may be used to cause magnetic field resonance. 
     The magnetic field resonance may be set to a suitable resonance frequency, and the frequency of the high-frequency power output from the high-frequency power supply  11  may be set accordingly. In other words, instead of the high-frequency power. AC power having a predetermined frequency, e.g., 10 kHz to 10 MHz may be used. 
     In the embodiment, the power supply controller  15  determines whether or not the secondary coil  21   a  is located at a position where power is receivable from the primary coil  13   a  based on whether or not communication may be established with the vehicle controller  24 . Instead of performing the determination with such a configuration, for example, the non-contact power supplying apparatus  10  may include any type of a sensor, such as an image sensor, to detect whether or not the vehicle is located at a chargeable position, and the determination may be performed based on the detection result of the sensor. In this case, the non contact power supplying apparatus  10  may recognize the presence of the vehicle when communication cannot be established between the controllers  15  and  24  even though they are within the communicable distance. 
     In the embodiment, the power supply controller  15  is configured to perform abnormality determination using the ratio of the output current to the output voltage and abnormality determination using the phase difference. Instead, the power supply controller  15  may be configured to perform only one of these abnormality determinations. However, to narrow the cause of the abnormality, it is preferable that both abnormality determinations be performed. 
     In the embodiment, the detection unit  16  detects the output voltage and the output current and detects the phase difference of the output voltage and current. Instead, the phase difference may not be detected, and only the output voltage and the output current or only the ratio of the output current to the output voltage may be detected. 
     In the embodiment, the power supply controller  15  is configured to calculate the ratio of the output current to the output voltage. Instead, for example, the detection unit  16  may be configured to calculate the ratio and output the calculation result to the power supply controller  15 . As long as the ratio can be detected, any configuration may be employed. 
     In the embodiment, the indicator  17  is used to indicate an abnormality. Instead, for example, the vehicle may indicate an abnormality. In this case, when the power supply controller  15  becomes communicable with the vehicle controller  24 , the power supply controller  15  transmits a signal indicating an abnormality to the vehicle controller  24 . When receiving the signal, the vehicle controller  24  uses a predetermined indicator to indicate the abnormality. The predetermined indicator may be an additional separate indicator or may be an existing device, such as a car navigation device that indicates the abnormality on a display or the like. 
     In the embodiment, the primary coil  13   a  is formed by a Litz wire, in which conductive wires are bundled. Instead, the primary coil  13   a  may be formed by, for example, a single conductive wire. In this case, when the conductive wire partially breaks, the resistance at the broken portion can be expected to increase greatly. Nevertheless, it is preferable that a Litz wire be used to limit increases in energy losses caused by the skin effect. 
     In the embodiment, when the phase difference of the output voltage and the output current is outside a specified range under a situation in which the ratio of the output current to the output voltage is smaller than the threshold, the power supply controller  15  determines the occurrence of a deformation in the primary coil  13   a . Instead, an abnormality in the primary capacitor  13   b  may be determined. 
     In the embodiments, the power supply controller  15  detects the abnormalities in the cable  14  and the power transmission circuit  13  based on the detection result from the detection unit  15 . Instead, the power supply controller  15  may detect an abnormality in the power supply main circuit  12  based on the detection result. 
     In the embodiments, fixed values are used for the threshold and the specified range. Instead, the threshold and the specified range may be varied in accordance with factors such as chronological wear or ambient temperature. In this Case, even when the output voltage and the output current is changed by the above factors when the high-frequency power for abnormality determination is output under a situation in which the vehicle is located at a chargeable position, the change may be coped with in a preferable manner. 
     In the embodiment, the vehicle battery  23  is arranged in the onboard apparatus  20 , and the power transmitted in a non-contact manner from the power supply main circuit  12  is used to charge the vehicle battery  23 . Instead, for example, the power may be used to operate a different electronic appliance such as the vehicle controller  24 . 
     In the embodiment, the power reception circuit  21 , which includes the secondary coil  21   a  used for non-contact power transmission, is installed in the vehicle but instead may be installed in, for example, a cellular phone. Any appliance may be subject to the power transmission.