Patent Publication Number: US-10766373-B2

Title: Power-feeding device

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 15/949,476 filed Apr. 10, 2018, which is a continuation of U.S. patent application Ser. No. 14/778,425 filed Sep. 18, 2015, which is a national stage of PCT/JP2014/001606 filed Mar. 20, 2014, which claims priority to Japanese Patent Application 2013-060080 filed Mar. 22, 2013, the entireties of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to a power supply apparatus that supplies power to an external power receiving section using an electromagnetic force in a wireless manner. 
     BACKGROUND ART 
     Conventionally, wireless power supply systems have been known in which power is supplied while a power supply coil and a power receiving coil are placed facing each other in a wireless manner. In such wireless power supply systems, when vibration is added to the power supply side during power supply due to an earthquake or the like, the position of the power supply coil changes. 
     For example, in a wireless power supply system that supplies power to a power storage apparatus mounted on a vehicle such as an electric vehicle, a power supply apparatus is installed on the ground. In this case, when an earthquake occurs or when a large vehicle passes by, vibration occurs in the power supply apparatus and the position of the power supply coil changes. When a wireless power supply system to supply power to a portable device is mounted on a mobile unit such as a vehicle, vibration occurs and the position of the power supply coil changes as the mobile unit moves. 
     When the position of the power supply coil changes during power supply, coupling between the power supply coil and the power receiving coil changes, causing excessive output or an increase in magnetic flux leakage. 
     Conventionally, wireless power supply systems configured to stop a charging section mounted on the vehicle when an unexpected situation such as an earthquake occurs have been known (e.g.,  FIG. 10  in Patent Literature (hereinafter, referred to as “PTL”) 1). When an unexpected situation occurs, the wireless power supply system of PTL 1 performs control of stopping power supply to a power storage apparatus by ECU. When resumption of the power supply is impossible, the power receiving side notifies the power supply side through communication that the power supply stops. Thus, the technique in PTL 1 can reduce excessive output or an increase in magnetic flux leakage associated with a change in the coupling between the power supply coil and the power receiving coil. 
     CITATION LIST 
     Patent Literature 
     PTL 1 
     WO 2010/137145 
     SUMMARY OF INVENTION 
     Technical Problem 
     However, according to PTL 1, since the power receiving side performs control of stopping power supply, it takes a considerable time until the power supply stops after an unexpected situation occurs. Thus, there is a problem that it is not possible to reduce excessive output or an increase in magnetic flux leakage for this time period. 
     An object of the present invention is to provide a power supply apparatus capable of minimizing excessive output or an increase in magnetic flux leakage by controlling power supply on the power supply side when an unexpected situation occurs. 
     Solution to Problem 
     A power supply apparatus according to the present invention supplies power to an external power receiving section in a wireless manner, the power supply apparatus including: a power supply coil that supplies power to a power receiving coil of the power receiving section using an electromagnetic force; and a control section that controls an amount of power supply based on an amount of displacement of the power supply coil when power is supplied from the power supply coil. 
     Advantageous Effects of Invention 
     According to the present invention, it is possible to minimize excessive output or an increase in magnetic flux leakage by controlling the amount of power supply on the power supply side when an unexpected situation occurs. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a block diagram illustrating a configuration of a power supply system according to an embodiment of the present invention; 
         FIG. 2  is a flowchart illustrating an operation of a power supply apparatus according to an embodiment of the present invention; and 
         FIG. 3  is a diagram illustrating an arrangement of acceleration sensors according to the embodiment of the present invention. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. 
     Embodiment 
     Configuration of Power Supply System 
     A configuration of power supply system  10  according to an embodiment of the present invention will be described using  FIG. 1 . 
     Power supply system  10  is mainly composed of power supply apparatus  100 , power receiving apparatus  150  and power supply target  160 . 
     Power supply apparatus  100  supplies power to power receiving apparatus  150 . 
     By receiving power supply from power supply apparatus  100 , power receiving apparatus  150  supplies power to power supply target  160 . 
     Power supply target  160  is a load or battery, for example. 
     Power supply system  10  is used when charging in a wireless manner a battery which is mounted on a vehicle, when charging in a wireless manner a battery incorporated in an electric device such as a mobile phone or when supplying power to a load such as a motor to drive the load. When a vehicle-mounted battery is charged in a wireless manner, power supply apparatus  100  is installed on the ground such as a parking area and power receiving apparatus  150  is mounted on a vehicle. 
     Configuration of Power Supply Apparatus 
     A configuration of power supply apparatus  100  according to the embodiment of the present invention will be described using  FIG. 1 . 
     Power supply apparatus  100  is mainly composed of power supply  101 , inverter  102 , power supply coil  103 , power-supply-side communication section  104 , acceleration sensor  105 , angular velocity sensor  106 , and power-supply-side control section  107 . 
     Power supply  101  supplies power to inverter  102 . 
     Inverter  102  converts DC power supplied from power supply  101  to AC power under the control of power-supply-side control section  107  and supplies a predetermined amount of AC power to power supply coil  103 . Inverter  102  changes the amount of power supplied to power supply coil  103  under the control of power-supply-side control section  107 . 
     Upon receiving power supply from inverter  102 , power supply coil  103  supplies power to power receiving coil  154 . Power supply coil  103  and power receiving coil  154  are planar spiral coils, for example. Power supply coil  103  supplies power in the amount of power corresponding to the amount of power supplied from inverter  102 . When supplying power, power supply coil  103  is magnetically coupled with power receiving coil  154  while facing power receiving coil  154 . Power supply coil  103  supplies power to power receiving coil  154  according to, for example, an electromagnetic induction scheme or magnetic resonance scheme using an electromagnetic force. 
     Power-supply-side communication section  104  exchanges information relating to power supply start or power supply stop with power-receiving-side communication section  153  under the control of power-supply-side control section  107  through wireless communication. Power-supply-side communication section  104  outputs, on the basis of the exchanged information, to power-supply-side control section  107 , a signal indicating that power supply is possible or a signal indicating that power supply is not possible. 
     Acceleration sensor  105  is installed in the periphery of power supply coil  103 . Acceleration sensor  105  detects acceleration of power supply apparatus  100  and outputs the detection value to power-supply-side control section  107 . By detecting the acceleration of power supply apparatus  100 , acceleration sensor  105  detects acceleration of power supply coil  103 . Acceleration sensor  105  is, for example, a triaxial acceleration sensor that can detect acceleration in three mutually orthogonal axial directions. 
     Angular velocity sensor  106  is installed in the periphery of power supply coil  103 . Angular velocity sensor  106  detects an angular velocity of power supply apparatus  100  and outputs the detection value to power-supply-side control section  107 . By detecting the angular velocity of power supply apparatus  100 , angular velocity sensor  106  detects an angular velocity of power supply coil  103 . Angular velocity sensor  106  is, for example, a triaxial angular velocity sensor that can detect angular velocities in three mutually orthogonal axial directions. 
     Upon receiving a signal indicating that power supply is possible from power-supply-side communication section  104 , power-supply-side control section  107  controls inverter  102  so as to supply the power of power supply  101  to power supply coil  103 . Upon receiving a signal indicating that power supply is not possible from power-supply-side communication section  104 , power-supply-side control section  107  controls inverter  102  so as to stop the power supply from power supply  101  to power supply coil  103 . 
     During power supply during which power is being supplied from power supply  101  to power supply coil  103 , power-supply-side control section  107  accumulates detection values indicating the displacement of power supply coil  103  received from acceleration sensor  105  or angular velocity sensor  106  for a predetermined time, and thereby calculates the amount of displacement of power supply coil  103 . Power-supply-side control section  107  controls inverter  102  based on the calculated amount of displacement, and thereby controls the amount of power supply. 
     More specifically, when the amount of displacement is equal to or greater than a threshold, power-supply-side control section  107  controls inverter  102  so that the amount of power supplied to power supply coil  103  becomes small compared to the case where the amount of displacement is smaller than the threshold. Furthermore, when the amount of displacement is equal to or greater than the threshold, power-supply-side control section  107  controls inverter  102  so as to stop power supply to power supply coil  103 . Furthermore, when the amount of displacement is equal to or greater than threshold A but less than threshold B (threshold B&gt;threshold A), power-supply-side control section  107  controls inverter  102  so that the amount of power supplied to power supply coil  103  is reduced compared to the case where the amount of displacement is less than threshold A, and power-supply-side control section  107  controls inverter  102  so as to stop the power supply to power supply coil  103  when the amount of displacement is equal to or greater than threshold B. Here, stopping power supply means reducing the amount of power supplied from power supply coil  103  to “zero”. 
     Note that, for example, when charging system  10  is mounted on a vehicle, an acceleration sensor and an angular velocity sensor provided for a car navigation apparatus may be also used as acceleration sensor  105  and angular velocity sensor  106 . 
     Configuration of Power Receiving Apparatus 
     A configuration of power receiving apparatus  150  according to the embodiment of the present invention will be described using  FIG. 1 . 
     Power receiving apparatus  150  is mainly composed of power-receiving-side control section  151 , inverter  152 , power-receiving-side communication section  153  and power receiving coil  154 . 
     Upon receiving a signal indicating that power supply is possible from power-receiving-side communication section  153 , power-receiving-side control section  151  controls inverter  152  so as to supply the power received by power receiving coil  154  to power supply target  160 . Upon receiving a signal indicating that power supply is not possible from power-receiving-side communication section  153 , power-receiving-side control section  151  controls inverter  152  so as to stop supplying the power received by power receiving coil  154  to power supply target  160 . 
     Inverter  152  converts AC power supplied from power receiving coil  154  to DC power under the control of power-receiving-side control section  151  and supplies the DC power to power supply target  160 . Note that, a rectifier using a diode, for example, may also be used to convert AC to DC instead of inverter  152 . 
     Power-receiving-side communication section  153  exchanges information relating to power supply start or power supply stop with power-supply-side communication section  104  through wireless communication under the control of power-receiving-side control section  151 . Based on the exchanged information, power-receiving-side communication section  153  outputs a signal indicating that power supply is possible or a signal indicating that power supply is not possible to power-receiving-side control section  151 . 
     Power receiving coil  154  receives power from power supply coil  103 . 
     Operation of Power Supply Apparatus 
     An operation of power supply apparatus  100  according to the embodiment of the present invention will be described using  FIG. 2 . 
     First, power supply apparatus  100  determines whether or not there is a power-supply-start instruction (step ST 201 ). 
     When there is no power-supply-start instruction (step ST 201 : No), power supply apparatus  100  repeats the process in step ST 201 . 
     On the other hand, in power supply apparatus  100 , when there is a power-supply-start instruction (step ST 201 : Yes), power-supply-side control section  107  determines whether or not power supply is possible by receiving a signal indicating that power supply is possible (step ST 202 ). Upon receiving a signal indicating that power supply is possible, power-supply-side control section  107  determines that power supply is possible and upon receiving a signal indicating that power supply is not possible, power-supply-side control section  107  determines that power supply is not possible. 
     When power supply is not possible (step ST 202 : No), power supply apparatus  100  ends the process. 
     On the other hand, when power supply is possible (step ST 202 : Yes), power supply apparatus  100  sets a power supply condition (step ST 203 ) and starts power supply (step ST 204 ). 
     Next, in power supply apparatus  100 , power-supply-side control section  107  determines whether or not a displacement of power supply coil  103  has been detected (step ST 205 ). Upon receiving a detection value from acceleration sensor  105  or angular velocity sensor  106 , power-supply-side control section  107  determines that a displacement has been detected. Here, the term “displacement” refers to a positional change. 
     In power supply apparatus  100 , when no displacement of power supply coil  103  has been detected (step ST 205 : No), power-supply-side control section  107  determines whether or not an overcurrent or overvoltage has occurred (step ST 206 ). 
     On the other hand, in power supply apparatus  100 , when a displacement of power supply coil  103  has been detected (step ST 205 : Yes), power-supply-side control section  107  determines whether or not the amount of displacement is equal to or greater than threshold A (step ST 207 ). 
     When the amount of displacement is less than threshold A (step ST 207 : No), power supply apparatus  100  proceeds to a process in step ST 206 . 
     On the other hand, in power supply apparatus  100 , when the amount of displacement is equal to or greater than threshold A (step ST 207 : Yes), power-supply-side control section  107  determines whether or not the amount of displacement is equal to or greater than threshold B (threshold B&gt;threshold A) (step ST 208 ). 
     In power supply apparatus  100 , when the amount of displacement is equal to or greater than threshold B (step ST 208 : Yes), power-supply-side control section  107  performs control so as to stop power supply from power supply coil  103  (step ST 209 ) and ends the process. 
     On the other hand, in power supply apparatus  100 , when the amount of displacement is less than threshold B (step ST 208 : No), power-supply-side control section  107  performs control so that the amount of power supply from power supply coil  103  is reduced compared to the case where the amount of displacement is equal to or greater than threshold B (step ST 210 ), and then proceeds to step ST 206 . 
     In step ST 206  when an overcurrent or overvoltage has occurred (step ST 206 : Yes), power supply apparatus  100  performs control so as to stop power supply from power supply coil  103  (step ST 209 ) and ends the process. 
     On the other hand, when no overcurrent or overvoltage has occurred in step ST 206  (step ST 206 : No), power supply apparatus  100  determines whether or not a power-supply-stop instruction has been received from the outside (step ST 211 ). 
     When a power-supply-stop instruction has been received from the outside (step ST 211 : Yes), power supply apparatus  100  performs control so as to stop power supply from power supply coil  103  (step ST 209 ), and ends the process. 
     On the other hand, when no power-supply-stop instruction has been received (step ST 211 : No), power supply apparatus  100  returns to the process in step ST 205 . 
     Note that in  FIG. 2 , when the amount of displacement is equal to or greater than threshold B, the power supply is stopped to end the process, but power supply may be resumed when the amount of displacement is less than threshold B after stopping the power supply. 
     Arrangement of Acceleration Sensors 
     An arrangement of acceleration sensors  105  according to the embodiment of the present invention will be described using  FIG. 3 . 
       FIG. 3  illustrates an arrangement of acceleration sensors  105  as seen from a direction in which power supply coil  103  and power receiving coil  154  face each other (direction shown by arrow  51  in  FIG. 1 ). 
     For example, in the case where one acceleration sensor  105  detects a displacement of power supply coil  103 , in a rotation around acceleration sensor  105 , the position of power supply coil  103  with respect to power receiving coil  154  is shifted regardless of acceleration “zero” and the state of coupling between power supply coil  103  and power receiving coil  154  changes. 
     In order to solve the above problem, three acceleration sensors  105   a,    105   b  and  105   c  are arranged in the manner shown in  FIG. 3 . That is, acceleration sensors  105   a,    105   b  and  105   c  are arranged at vertices of triangle E 1  respectively. Thus, power supply apparatus  100  can detect a displacement in all directions of power supply coil  103 . 
     Note that instead of arranging three acceleration sensors  105   a,    105   b  and  105   c  as shown in  FIG. 3 , power supply apparatus  100  can detect the displacement of power supply coil  103  in all directions using one acceleration sensor  105   a  capable of detecting acceleration in triaxial directions and one angular velocity sensor  106  capable of detecting angular velocities in triaxial directions. 
     Although three acceleration sensors  105   a,    105   b  and  105   c  are arranged at vertices of triangle E 1  respectively, the acceleration sensors may also be arranged at vertices of a polygon other than a triangle unless a plurality of acceleration sensors are arranged on a single straight line. The acceleration sensors are arranged at vertices of a polygon because when a plurality of acceleration sensors are arranged on a single straight line, if a displacement that rotates around this straight line as the axis of rotation occurs, it is no longer possible to detect the displacement. 
     Moreover, when acceleration sensor  105  is arranged as shown in  FIG. 3 , angular velocity sensor  106  may be omitted. 
     As long as displacements and rotations in triaxial directions of power supply coil  103  can be detected, any given number of acceleration sensors  105  and angular velocity sensors  106  can be arranged in any given arrangement. 
     When a mechanical restricting section for restricting a displacement in a specific one or multiple directions is provided separately, and a displacement in a direction in which the section for restricting the displacement thereby need not be detected, or when the influence of the displacement on the power supply is sufficiently small, the number of axes of acceleration sensors  105  and angular velocity sensor  106  may be fewer than three or one of acceleration sensor  105  and angular velocity sensor  106  may be omitted. 
     Threshold to be Compared with Amount of Displacement of Power Supply Coil 
     A threshold with which the amount of displacement of power supply coil  103  according to the embodiment of the present invention is compared will be described. 
     When a mechanical restricting section for restricting a displacement of power supply coil  103  is provided or a mechanical restricting section for restricting a relative displacement between power supply coil  103  and power receiving coil  154  is provided separately, it is possible to make a threshold to be compared with the amount of displacement of power supply coil  103  with respect to the direction in which the restricting section is provided greater than a threshold to be compared with the amount of displacement of power supply coil  103  with respect to another direction. 
     Examples of the mechanical restricting section include a member that comes into contact with power supply apparatus  100  when power supply apparatus  100  displaces to prevent further a displacement of power supply apparatus  100  or a member that restricts a relative displacement between power supply coil  103  and power receiving coil  154 . 
     Thus, when power supply coil  103  displaces in the direction in which the restricting section is provided, or when the relative displacement between power supply coil  103  and power receiving coil  154  by provision of the restricting section is small, and in a situation in which continuation of power supply poses no problem, it is possible to prevent a reduction in the amount of power supply or the power supply from being stopped. 
     Effects of Present Embodiment 
     The present embodiment controls power supply on the power supply side when an unexpected situation occurs and can thereby minimize excessive output or an increase in magnetic flux leakage. 
     The present embodiment arranges the acceleration sensors at vertices of a polygon respectively, and can thereby detect a displacement of power supply coil  103  in all detections. 
     The present embodiment uses triaxial gyroscopes as angular velocity sensors  106 , and can thereby reduce the number of sensors for detecting a displacement of power supply coil  103  and reduce the manufacturing cost. 
     The present embodiment reduces the amount of power supply when the amount of displacement of power supply coil  103  is equal to or greater than threshold A but less than threshold B, and can thereby reduce the frequency with which power supply is stopped compared to a case where power supply is immediately stopped. 
     Variations of Present Embodiment 
     The present embodiment reduces the amount of power supply when the amount of displacement of power supply coil  103  is equal to or greater than threshold A but less than threshold B, but the power supply may be immediately stopped when the amount of displacement of power supply coil  103  is equal to or greater than threshold A. 
     The present embodiment detects a displacement of power supply coil  103  using acceleration sensor  105  or angular velocity sensor  106 , but any given sensor can be used if this can detect a displacement of power supply coil  103 . 
     In the present embodiment, the installation location of the power supply apparatus is not limited to the ground but may be a mobile unit such as an automobile, railway vehicle, aircraft, ship or playground equipment. In this case, for example, the power receiving side may be a small electronic device such as a portable device. 
     In the present embodiment, the power supply coil and the power receiving coil are assumed to be planar spiral coils, but any coil other than the spiral coil may be used if this is a coil which can transmit and/or receive power, and a solenoid coil may be used, for example. 
     The disclosure of Japanese Patent Application No. 2013-060080, filed on Mar. 22, 2013, including the specification, drawings and abstract is incorporated herein by reference in its entirety. 
     INDUSTRIAL APPLICABILITY 
     The present invention is suitable for use in a power supply apparatus that supplies power to an external power receiving section using an electromagnetic force in a wireless manner. 
     REFERENCE SIGNS LIST 
     
         
           10  Power supply system 
           100  Power supply apparatus 
           101  Power supply 
           102  Inverter 
           103  Power supply coil 
           104  Power-supply-side communication section 
           105  Acceleration sensor 
           106  Angular velocity sensor 
           107  Power-supply-side control section 
           150  Power receiving apparatus 
           151  Power-receiving-side control section 
           152  Inverter 
           153  Power-receiving-side communication section 
           154  Power receiving coil 
           160  Power supply target