JP2016178810A - Non-contact power supply system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a non-contact power supply system capable of simply determining whether or not a positional deviation between a power transmission unit and a power reception unit is within an allowable range.SOLUTION: A non-contact power supply system 1 comprises: a power transmission unit 10 having a first resonant circuit 12 including a power transmission coil 12a; a power reception unit 20 that has a second resonant circuit 21 including a power reception coil 21a and receives power in a non-contact manner from the power transmission unit 10; and a control unit 15 for controlling power supply from the power transmission unit 10 to the power reception unit 20. The control unit 15 detects a variation in a characteristic value on power supply generated depending on the amount MA of positional deviation between the power transmission coil 12a and the power reception coil 21a; and, on the basis of the variation in the characteristic value, executes determination control of determining whether or not the positional deviation between the power transmission coil 12a and the power reception coil 21a is within an allowable range.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a non-contact power feeding system.

  A technique related to a non-contact power feeding system including a power transmission unit including a power transmission coil and a power reception unit including a power reception coil that receives power in a non-contact manner from the power transmission coil is known. As such a technique, for example, in the power transmission system described in Patent Document 1, the relationship between the reflected power that is reflected from the power output from the power transmission unit and returned to the power transmission unit and the positional deviation is prepared in advance. Yes. Based on this relationship and the detected actual reflected power, a positional shift between the power transmission coil and the power reception coil is detected. Moreover, in the parking assistance apparatus described in Patent Document 2, the positional relationship between the power reception unit of the vehicle and the power transmission unit of the power supply apparatus is detected based on an image captured by the camera. Based on the detection result, the vehicle is controlled to guide the vehicle to the power transmission unit. Moreover, in the parking assistance apparatus described in Patent Document 3, the relationship between the distance between the power transmission unit and the power reception unit and the power reception status is determined in advance according to the output of the height sensor that detects a change in vehicle height. Using this relationship, alignment is performed based on the output of the height sensor and the power reception status.

JP 2013-074673 A JP2011-188679A Republished patent WO2011 / 132272

  In the technique described in Patent Document 1, the relationship between the reflected power and the positional deviation changes depending on the attachment position of the power transmission coil or the power reception coil. Therefore, for example, there is a problem that this relationship needs to be reset according to the vehicle on which the power receiving coil is mounted, which is complicated. In addition, the techniques described in Patent Document 2 and Patent Document 3 require devices such as a camera and a height sensor. For this reason, there is a problem in that the increase in these devices leads to complicated control and cost increase of the non-contact power feeding system.

  Then, an object of this invention is to provide the non-contact electric power feeding system which can determine easily whether the position shift between a power transmission coil and a receiving coil is a tolerance | permissible_range.

  A non-contact power feeding system according to one aspect of the present invention includes a power transmission unit having a first resonance circuit including a power transmission coil and a second resonance circuit including a power reception coil, and a power reception unit that receives power in a non-contact manner from the power transmission unit. And a control unit that controls power supply from the power transmission unit to the power reception unit, and the control unit detects a change in a characteristic value related to power supply that occurs according to a positional deviation amount between the power transmission coil and the power reception coil. Then, determination control is performed to determine whether the positional deviation between the power transmission coil and the power reception coil is within an allowable range based on the change in the characteristic value.

  In the non-contact power feeding system, the first resonance circuit includes a power transmission coil, and the second resonance circuit includes a power reception coil. And the change of the characteristic value regarding the electric power supply which arises according to the amount of position shift between a power transmission coil and a receiving coil is detected by a control part. The degree of coupling between the power transmitting coil and the power receiving coil changes according to the amount of positional deviation, and the characteristic value applied to the power receiving unit changes. Therefore, it is possible to grasp the change in the distance between the power transmission coil and the power reception coil (distance between power transmission and reception) by detecting the change in the characteristic value. Therefore, it is possible to easily determine whether or not the positional deviation between the power transmission coil and the power reception coil is within the allowable range based on the change in the characteristic value.

  After the determination control is started, the control unit reduces the characteristic value while the characteristic value decreases from a value lower than the range of values that the characteristic value can take when the positional deviation is within the allowable range. When the threshold value is smaller than the maximum value, it may be determined that the positional deviation is within the allowable range. In this case, after the determination control is started, there is a positional deviation amount in which the characteristic value becomes a maximum value from a value lower than the range of values that the characteristic value can take when the positional deviation is within an allowable range. By utilizing this property, it is possible to determine that the positional deviation is within the allowable range when the characteristic value becomes a threshold value smaller than the maximum value while the characteristic value decreases after reaching the maximum value.

  The characteristic value may be a voltage applied to the power receiving unit by supplying power from the power transmitting unit. In this case, a change in the characteristic value relating to power supply can be easily detected.

  The contactless power supply system may further include a notifying unit that notifies that when the control unit determines that the positional deviation is within the allowable range. In this case, for example, a driver of a vehicle equipped with a non-contact power feeding system can easily recognize whether the positional deviation is within an allowable range.

  ADVANTAGE OF THE INVENTION According to this invention, the non-contact electric power feeding system which can determine easily whether the position shift between a power transmission coil and a receiving coil is a tolerance | permissible_range can be provided.

It is the schematic of the non-contact electric power feeding system of embodiment of this invention. It is a block diagram which shows the structure of the non-contact electric power feeding system in FIG. It is a flowchart which shows the process of the determination control by a control part. (A) is a diagram showing a state where the vehicle is located outside the allowable range, (b) is a diagram showing a state where the vehicle has reached the allowable range, and (c) is a diagram showing a state where the vehicle is located within the allowable range. is there. It is a figure which shows the voltage applied to a power receiving part by the electric power supply from a power transmission part.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted.

  As shown in FIGS. 1 and 2, the non-contact power feeding system 1 is a system (apparatus) for charging a battery B mounted on a vehicle 2 such as an electric vehicle or a hybrid vehicle. In FIG. 1, the Y direction corresponds to the longitudinal direction of the vehicle 2, and the Z direction corresponds to the vertical direction of the vehicle 2.

  The non-contact power supply system 1 includes a power transmission device 3 installed on the ground side and a power reception device 4 provided on the vehicle 2 side. The power transmission device 3 is configured to be able to transmit power (power for charging the battery B) to the power receiving device 4 of the vehicle 2 in a contactless manner. For example, when the vehicle 2 traveling on the ground is stopped in a predetermined positional relationship, the power transmission device 3 transmits power in a non-contact manner.

  The power transmission device 3 includes a power transmission unit 10, a first communication unit 14, and a control unit 15. The power transmission unit 10 is connected to an external power source 13 (for example, a commercial power source) and is a device for transmitting power to the vehicle 2 in a contactless manner. The power transmission unit 10 includes a first power converter 11 and a first resonance circuit 12.

  The first power converter 11 is a circuit that converts AC power supplied from the external power supply 13 into high-frequency power. The first power converter 11 is stored in the main body 3 a of the power transmission device 3. The first power converter 11 includes, for example, a rectifier and an inverter circuit. The rectifier converts (rectifies) AC power from the external power source 13 into DC power, and the inverter circuit converts the DC power to the external power source 13. Conversion to AC power (high frequency power) having a higher frequency than AC power. The first power converter 11 transmits the converted high frequency power to the first resonance circuit 12.

  The first resonance circuit 12 supplies the electric power supplied from the first power converter 11 to the vehicle 2 in a contactless manner. The first resonance circuit 12 is embedded in the ground R, and is installed so that the upper surface thereof is flush with the ground R. The first resonance circuit 12 may be installed so as to protrude from the ground R. The first resonance circuit 12 includes a power transmission coil 12a. The power transmission coil 12a is a coil for supplying electric power supplied from the first power converter 11 to the vehicle 2 in a non-contact manner, and has, for example, a predefined coil shape and dimensions. The shape of the power transmission coil 12a may be a circular type or a solenoid type. The first resonant circuit 12 realizes non-contact power feeding to the vehicle 2 by applying high-frequency power from the first power converter 11 to the power transmission coil 12a. The first resonance circuit 12 may include at least one capacitor in addition to the power transmission coil 12a, and may further include an inductor. The capacitor and the inductor are connected in parallel or in series with the power transmission coil 12a, and various circuit topologies are formed.

  In the first resonance circuit 12, a magnetic coupling circuit is formed with the second resonance circuit 21. More specifically, the magnetic coupling circuit is formed by positioning the power transmission coil 12a and the power reception coil 21a provided in the vehicle 2 in a close proximity. This magnetic coupling circuit means a circuit in which the power transmission coil 12a and the power reception coil 21a are magnetically coupled and non-contact power feeding from the power transmission coil 12a to the power reception coil 21a is performed. The magnetic coupling circuit here is a circuit that supplies power by the “magnetic resonance method”. The magnetic coupling circuit may be a circuit that supplies power by an “electromagnetic induction method”.

  The first resonance circuit 12 enables non-contact power feeding by transmitting power from the power transmission coil 12a to the power reception coil 21a of the vehicle 2 via a magnetic coupling circuit. The first resonance circuit 12 supplies power to the vehicle 2 in a non-contact manner according to the degree of coupling K of the magnetic coupling circuit between the first resonance circuit 12 and the second resonance circuit 21. The degree of coupling K is the degree of magnetic coupling between the power transmission coil 12a and the power reception coil 21a. The degree of coupling K varies depending on the specifications (for example, shape) of the power transmission coil 12a and the power reception coil 21a, the distance between power transmission and reception, and the like, and can take a value of 0 to 1. The degree of coupling K approaches 1 as the degree of magnetic coupling increases, and approaches 0 as the degree of magnetic coupling decreases.

  The degree of coupling K tends to approach 1 because the degree of magnetic coupling tends to increase as the distance between power transmission and reception decreases. The degree of coupling K tends to approach 0 because the degree of magnetic coupling tends to be weaker as the distance between power transmission and reception is larger. Here, the distance between the power transmission and reception is the distance at which the power transmission coil 12a and the power reception coil 21a are separated in the direction intersecting the vertical direction (for example, the Y direction in FIG. 1) (that is, the power transmission unit 10 in the front-rear direction and the left-right direction of the vehicle 2). And the amount of displacement between the power receiving unit 20). Note that the distance (that is, the gap in the height direction of the vehicle 2) in which the power transmission coil 12a and the power reception coil 21a are separated in the vertical direction (Z direction in FIG. 1) depends on, for example, the type of the vehicle 2 on which the power reception unit 20 is mounted. Change.

  The external power supply 13 is a power supply that supplies power necessary to generate power to be transmitted to the vehicle 2 and supplies, for example, three-phase AC power having a voltage of 200 [V]. The external power source 13 is not limited to three-phase AC power, and may be a power source that supplies single-phase AC power such as a commercial AC power source. The external power supply 13 is stored in the main body 3 a of the power transmission device 3.

  The first communication unit 14 is an interface for performing wireless communication. The first communication unit 14 is provided in the main body 3 a of the power transmission device 3. The first communication unit 14 communicates with the second communication unit 23 provided in the vehicle 2. The second communication unit 23 is mounted on the vehicle 2. For example, a wireless LAN or Bluetooth (registered trademark) can be used as the first communication unit 14.

  The control unit 15 is an electronic control unit including, for example, a CPU [Central Processing Unit], a ROM [Read Only Memory], a RAM [Random Access Memory], and the like. The control unit 15 controls power supply from the power transmission unit 10 to the power reception unit 20. The control unit 15 controls the power transmission unit 10 so as to change the magnitude of power supplied from the power transmission unit 10 to the power reception unit 20. For example, when an abnormality occurs in the power receiving unit 20 on the vehicle 2 side or the like, the control unit 15 can control the power supply from the power transmitting unit 10 to the power receiving unit 20 to stop. Since the control unit 15 is provided on the power transmission side, an increase in size of the power reception unit 20 on the vehicle 2 side can be suppressed.

  Moreover, the control part 15 performs the determination control which determines whether the position shift between the power transmission coil 12a and the receiving coil 21a is an allowable range. Here, the allowable range is a range of misalignment in which non-contact power feeding from the power transmission coil 12a to the power reception coil 21a is possible. The positional deviation capable of non-contact power feeding means that the positional relationship between the power transmission coil 12a and the power receiving coil 21a is magnetic coupling that enables power supply of a desired power amount with desired efficiency between the power transmitting coil 12a and the power receiving coil 21a. This is a positional deviation when the positional relationship in which the circuit is formed is obtained. That is, the permissible range here is not only the case where the efficiency of power supply from the power transmission coil 12a to the power reception coil 21a is maximized, but also the positional deviation when the power supply efficiency of a practically satisfactory level is obtained. including. The control unit 15 executes control for approaching a situation in which there is no positional deviation rather than eliminating the positional deviation strictly so as to maximize the efficiency of power supply from the power transmission coil 12a to the power receiving coil 21a. When determining that the positional deviation is within the allowable range, the control unit 15 causes the driver of the vehicle 2 to notify the below-described notification unit 30 that the positional deviation is within the allowable range (transmission of a stop request).

The control unit 15 detects a change in the characteristic value related to the power supply that occurs according to the positional deviation amount MA between the power transmission coil 12a and the power reception coil 21a, and executes determination control based on the change in the characteristic value. Here, characteristic value is the voltage V ₂ applied to the power receiving coil 21a by the power supply from the power transmission coil 12a. The characteristic value may be not the voltage but the value of power received by the power receiving coil 21a. The control unit 15 to communicate with the second communication unit 23 via the first communication unit 14 detects a change in voltage V ₂ applied to the power receiving unit 20.

  The vehicle 2 includes a power receiving device 4, a notification unit 30, a battery B, and a charging circuit (not shown). Although omitted in FIG. 1, the vehicle 2 has a configuration necessary for traveling such as a motor, an operation handle, and a brake. The power receiving device 4 includes a power receiving unit 20 and a second communication unit 23.

The power receiving unit 20 is a device that receives power from the power transmission coil 12a in a contactless manner and receives the supplied power. The power receiving unit 20 includes a second resonance circuit 21 and a second power converter 22. The power reception unit 20 detects the voltage V ₂ applied to the power reception unit 20 by supplying power from the power transmission coil 12 a and transmits the voltage V ₂ to the second communication unit 23.

  The second resonance circuit 21 receives the electric power supplied from the first resonance circuit 12 in a contactless manner and transmits the electric power to the second power converter 22. The second resonance circuit 21 is provided at the bottom of the vehicle 2. The second resonance circuit 21 includes a power receiving coil 21a. The power receiving coil 21a is a coil for receiving electric power (AC power) supplied in a non-contact manner from the power transmission coil 12a, and has, for example, substantially the same coil shape and dimensions as the power transmission coil 12a. The shape of the power receiving coil 21a may be a circular type or a solenoid type. The second resonance circuit 21 includes at least one capacitor in addition to the power receiving coil 21a, and can further include an inductor. The capacitor and the inductor are connected in parallel or in series with the power receiving coil 21a to form various circuit topologies.

When the coupling degree K changes due to a change in the distance between the power transmission coil 12a and the power reception coil 21a, the impedance of the magnetic coupling circuit changes. Depending on the circuit topology of the first resonance circuit 12 and the second resonance circuit 21 and the frequency of the high-frequency power output from the first power converter 11, the characteristic value may become a maximum value when a displacement occurs. For example, the voltage V ₂ (characteristic value related to power supply) applied to the power receiving unit 20 by supplying power from the power transmitting unit 10 has a maximum value at the first distance. Maximum value of the voltage V ₂ is used in performing the determination control is detected by the control unit 15.

In the second resonance circuit 21, when the voltage V ₂ applied to the power receiving unit 20 has a maximum value, the power transmitted to the second power converter 22 becomes excessive, and the second power converter 22 is configured. In order to prevent an element (for example, a capacitor) from being damaged, a limiter (not shown) is provided. The circuit that may be damaged due to excessive power is not limited to the second power converter 22, and the second resonance circuit 21 and the power transmission unit 10 are also targets. Limiter, for example, suppress the voltage V ₂ applied to the power receiving portion 20 below suppression voltage V _L. Here, the suppression voltage V _L is larger than the voltage V _B applied to the power receiving unit 20 with the rated power for charging the battery B, for example. The voltage V _B is a voltage applied to the power receiving unit 20 when there is no abnormality in the power transmitting unit 10 and the power receiving unit 20 in a situation where the power transmitting coil 12a and the power receiving coil 21a face each other and charge the battery B. The limiter may suppress the current together with the voltage to a predetermined value or less, or may suppress the current to a predetermined value or less instead of the voltage.

  The second power converter 22 is a circuit that rectifies the high-frequency power transmitted from the second resonance circuit 21 and converts it into DC power. The second power converter 22 is mounted on the vehicle 2. The second power converter 22 includes, for example, a rectifier and a DC / DC converter circuit, and converts the high frequency power from the second resonance circuit 21 to DC power. The second power converter 22 supplies the converted DC power to the battery B. The battery B is a rechargeable battery (for example, a secondary battery such as a lithium ion battery or a nickel metal hydride battery) mounted on the vehicle 2 and supplies power to a travel motor (not shown). The charging circuit is controlled based on a power reception control program prepared in advance by a power reception control unit (not shown).

  The second communication unit 23 is an interface for performing wireless communication. The second communication unit 23 is mounted on the vehicle 2. The second communication unit 23 communicates with the first communication unit 14 on the ground side. As the second communication unit 23, for example, a wireless LAN or Bluetooth (registered trademark) can be used. Moreover, the 2nd communication part 23 transmits the signal which controls the alerting | reporting part 30 to the alerting | reporting part 30 mentioned later. In addition, the 2nd communication part 23 is not limited to implement | achieving both the function which communicates with the 1st communication part 14, and the function which communicates with the alerting | reporting part 30 with one hardware. Each of the communication function with the first communication unit 14 and the communication function with the notification unit 30 may be realized by separate hardware.

  When the control unit 15 determines that the positional deviation between the power transmission coil 12a and the power reception coil 21a is within the allowable range, the notification unit 30 notifies the driver of the vehicle 2 and the like. In this case, the notification unit 30 receives a signal from the second communication unit 23 so as to notify that the positional deviation is within the allowable range, and notifies the driver of the vehicle 2 that the vehicle 2 may be stopped. This prompts the driver of the vehicle 2 to stop the vehicle 2. The notification unit 30 includes a navigation system 31 and a speaker 32. Here, the notification unit 30 displays an image on the navigation system 31 for visual notification (display of a stop request). Note that the notification unit 30 may output the sound to the speaker 32 to make an audible notification, or may notify using the mobile phone terminal of the passenger of the vehicle 2 via the second communication unit 23.

  The determination control executed by the control unit 15 will be described with reference to FIGS. For simplification of description, the distance between power transmission and reception is the distance between the power transmission coil 12a and the power reception coil 21a in the direction intersecting the vertical direction (the front-rear direction of the vehicle 2 in the Y direction in FIG. 1). To do. At the origin O in FIG. 5, the positional deviation amount MA is 0, that is, the distance between the power transmission coil 12a and the power reception coil 21a is 0 in the Y direction. The plus and minus of the positional deviation amount MA means the positional deviation in the front direction or the rearward direction of the vehicle 2.

  As shown in FIG. 3, determination control is started by the control unit 15 (step S1). Subsequently, communication between the first communication unit 14 and the second communication unit 23 is started by the control unit 15 (step S2). Thereby, the presence of the power receiving device 4 is recognized by the power transmitting device 3, and the determination control is started by the control unit 15.

In step S1 and step S2, the vehicle 2 is in a state of being separated from the power transmission coil 12a, and the positional deviation amount MA is smaller than MA ₁ (see FIG. 4A). The absolute value (distance between power transmission and reception) of the positional deviation amount MA at this time is larger than the distance from the origin O to MA ₁ . That is, a magnetic coupling circuit is not formed between the first resonance circuit 12 and the second resonance circuit 21 to the extent that a desired non-contact power supply to the vehicle 2 can be realized. And the parking of the vehicle 2 is started by the driver | operator of the vehicle 2 so that the vehicle 2 approaches the power transmission coil 12a (step S3).

Next, electric power for confirming the position of the vehicle 2 is transmitted by the control unit 15 (step S4). In step S4, the control unit 15 transmits power for applying a voltage to the power receiving unit 20 by supplying power from the power transmitting unit 10 from the power transmitting coil 12a to the power receiving coil 21a. The power for position confirmation is a weak power smaller than the power for charging the battery B (for example, 3.3 kW). This object is achieved, for example, when the voltage V ₂ applied to the power receiving portion 20 is a maximum value, the power receiving unit 20 is supplied is prevented from being damaged becomes excessive. Moreover, the electromagnetic wave radiated | emitted around the power transmission coil 12a and the receiving coil 21a can be reduced by making the electric power for position confirmation into weak power.

Incidentally, for example, if the transmitting coil 12a and receiving coil 21a is the voltage V ₂ applied to the power receiving portion 20 in a situation that is not directly facing (when HiTadashitai) is increased (voltage rises), the voltage rise due to resonance it is desirable to distinguish between whether the local maximum of the voltage V ₂ or, alternatively the voltage rise due to abnormal. In this regard, in general, when the power transmission coil 12a and the power reception coil 21a face each other and charge the battery B (during charging), the voltage V during normal charging applied to the power reception unit 20 with the power for charging the battery B _B is smaller than the maximum value (maximum voltage V _C ) of the voltage V ₂ due to resonance. Thus, for example, the voltage rises until it reaches the inhibit voltage V _L at a power for localization during HiTadashitai, and, more voltage does not rise reaches the voltage V _B at power for charging the battery B at the time of charge in this case, the voltage rises at the time HiTadashitai can be determined that the maximum value of the voltage V ₂ due to resonance. On the other hand, when the voltage rises until it reaches the inhibit voltage V _L at a power for localization during HiTadashitai, and, the voltage rises enough to exceed the voltage V _B at power for charging the battery B during charging, It can be determined that the voltage increase at the time of non-facing may be a voltage increase due to abnormality.

Subsequently, the data relating to the voltage V ₂ applied to the power receiving unit 20 by the power transmitted in the In step S4 (receiving data) is transmitted by the second communication unit 23 to the first communication unit 14 (step S5) . The received power data is received by the control unit 15 via the first communication unit 14. Based on the received power data, the controller 15 estimates a parking position (step S6), and determines whether the estimated parking position is within an allowable range (step S7). If it is determined in step S7 that the parking position estimated by the control unit 15 is not within the allowable range, the process proceeds to step S4, and the process from step S4 to step S7 is repeated by the control unit 15. In the step S6 and step S7, by detecting the change in the voltage V ₂ applied to the power receiving unit 20, the change between the transmitting and receiving distance is grasped by the control unit 15, the parking position is estimated.

When the vehicle 2 approaches the transmitting coil 12a, a certain voltage V ₂ applied to the power receiving portion 20 in the first distance _{(characteristic} value) is the maximum voltage V _C. Further, when the vehicle 2 approaches the power transmission coil 12a, the voltage V ₂ becomes smaller, which is applied to the power receiving unit 20. Specifically, after the determination control is started by the control unit 15, when the positional deviation is within the allowable range, the voltage V ₂ applied to the power receiving unit 20 has a maximum voltage V from a value lower than a possible value range. while decreasing after reaching _{C, the} whether the voltage V ₂ becomes smaller threshold than the maximum voltage V _C is determined by the control unit 15. This threshold value is a value lower than the minimum withstand voltage among the withstand voltages of the elements of the power transmitting unit 10 and the power receiving unit 20, for example, and is set to the suppression voltage _VL . However, the threshold value is not limited to this example, and may be set by a test or the like.

In the example of FIG. 5, the voltage V ₂ (characteristic value relating to power supply) applied to the power receiving unit 20 by the power supply from the power transmission coil 12a becomes the maximum voltage V _C in the positional deviation amount MA _C. For example, if the transmitting coil 12a and receiving coil 21a is circular type, the positional relationship between the first resonant circuit 12 and the second resonant circuit 21 to produce a maximum voltage V _C, the first resonant circuit 12 and as viewed from the Z direction The second resonance circuit 21 exists concentrically around the position where it faces the center. The voltage V ₂ (characteristic value relating to power supply) applied to the power receiving unit 20 by the power supply from the power transmission coil 12a becomes the maximum voltage V _C in the positional deviation amount MA _C. Such positional relationship between the transmitting coil 12a and receiving coil 21a produces a maximum voltage V _C is the transmitting coil 12a and receiving coil 21a as viewed from the Z direction is present concentrically around the position directly facing.

The positional deviation amount MA includes a maximum voltage _{V C} is the voltage _{V 2} in the case of values between _MA 1 to MA ₂ is complex impedance of the magnetic coupling circuit of the first resonance circuit 12 and the second resonant circuit 21 is small It is because it became. The complex impedance can be described using a Smith chart in which the complex impedance is represented as a point on the complex plane. In the Smith chart, for example, the real axis of the complex impedance is the horizontal axis, and the imaginary axis of the complex impedance is the vertical axis. In the Smith chart, the complex impedance is 0Ω (short circuit) at one end of the horizontal axis, and the complex impedance is infinite (open) at the other end of the horizontal axis.

The change in complex impedance is represented as a change in absolute value and declination of the complex impedance in the Smith chart. Therefore, the point representing the complex impedance in the Smith chart moves so as to rotate about the origin of the Smith chart as the complex impedance changes. This movement with the resonating first resonant circuit 12 and the second resonant circuit 21 by the complex impedance is changed, the voltage V ₂ applied changes to the power receiving unit 20. By utilizing this phenomenon, by detecting the change in the voltage V ₂ applied to the power receiving unit 20, the change between the transmitting and receiving distance is grasped by the control unit 15, the parking position is estimated.

As illustrated in FIG. 4A, the determination control is started from a positional deviation amount MA (distance between power transmission and reception that is larger than the distance from the origin O to MA ₁ ) smaller than MA _1. After the start of the operation, there is a displacement amount MA _{C at} which the voltage V ₂ becomes the maximum voltage V _C. Accordingly, after the decision control by the control unit 15 is started, while the voltage V ₂ applied to the power receiving unit _{20 (characteristic} value) decreases after reaching the maximum voltage V _C, the characteristic value becomes inhibit voltage V _L Taka whether (whether the voltage V ₂ becomes amplitude level at a position shifted tolerance) by determining the can position deviation to determine whether the allowable range easily.

  Subsequently, when it is determined in step S7 that the parking position estimated by the control unit 15 is within the allowable range, the control unit 15 transmits a stop request to the notification unit 30 (step S8), and the notification unit 30 requests a stop. Is displayed on the navigation system 31 (step S9). For example, a display such as “charging OK” is displayed on the navigation system 31. Then, the displayed stop request is recognized by the driver of the vehicle 2, and the vehicle 2 is stopped (step S10). In this case, since the driver of the vehicle 2 performs a stop operation after recognizing the stop request, the vehicle 2 continues to move toward the second resonance circuit 21 by inertia. As a result, the vehicle 2 can be reliably stopped within the allowable range, and the vehicle 2 can be appropriately stopped at the parking position (optimum range) shown in FIG. In addition, when the vehicle 2 passes the optimal range, the determination control can be executed again.

As described above, in the non-contact power supply system 1, the power transmission unit 10 includes the first resonance circuit 12 including the power transmission coil 12a, and the power reception unit 20 includes the second resonance circuit 21 including the power reception coil 21a. Then, the control unit 15 detects a change in the characteristic value related to the power supply generated according to the positional deviation amount MA between the power transmission coil 12a of the first resonance circuit 12 and the power reception coil 21a of the second resonance circuit 21. The degree of coupling K between the power transmission coil 12a and the power reception coil 21a changes according to the positional deviation amount MA, and the voltage V ₂ (characteristic value) applied to the power reception unit 20 changes. Therefore, a change in the distance (distance between power transmission and reception) between the power transmission coil 12a and the power reception coil 21a can be grasped by detecting a change in the voltage V ₂ (characteristic value). Therefore, it is possible to easily determine whether or not the positional deviation between the power transmission coil 12a and the power reception coil 21a is within an allowable range based on the change in the characteristic value.

Control unit 15, after the determination control is started, decreases after reaching a value lower than the range of the voltage V ₂ can assume values as the voltage V ₂ is the maximum voltage V _C when the position deviation is acceptable while, when the voltage V ₂ becomes suppression voltage V _L, determines that the positional deviation is acceptable. Wherein the inhibit voltage V _L is a threshold value for positional deviation to determine whether the allowable range, smaller than the maximum voltage V _C. Thus, after the determination control is started, the positional deviation amount MA _{C at} which the voltage V ₂ becomes the maximum voltage V _C from a value lower than the range of values that the voltage V ₂ can take when the positional deviation is within an allowable range. Exists. Utilizing this property, may be between the voltage V ₂ decreases after reaching the maximum voltage V _C, the positional deviation when the voltage V ₂ becomes inhibit voltage V _L is acceptable.

The voltage V ₂ is a voltage applied to the power receiving unit 20 by supplying power from the power transmitting unit 10. Thereby, the change of the characteristic value regarding electric power supply can be detected easily.

  When the control unit 15 determines that the positional deviation is within the allowable range, the non-contact power feeding system 1 further includes a notification unit 30 that notifies that fact. Thereby, the driver | operator of the vehicle 2 carrying the non-contact electric power feeding system 1, for example can recognize easily whether a position shift is a tolerance | permissible_range.

  Although one embodiment of the present invention has been described above, the present invention is not limited to the above embodiment. For example, in the above-described embodiment, the position confirmation power is a weak power smaller than the power for charging the battery B (for example, 3.3 kW). However, the power is the same as the power for charging the battery B. It is good.

  In the above embodiment, an example in which the charging position is guided by the non-contact power feeding system 1 when the driver drives and parks the vehicle 2 has been described. However, for example, automatic parking by a parking assistance device or the like mounted on the vehicle 2 In this case, the charging position may be guided by the non-contact power feeding system 1.

  In the above embodiment, the power transmission device 3 is fixed to the ground side, and the power reception device 4 is mounted on the vehicle 2 and is movable with respect to the power transmission device 3. However, for example, the power transmission device 4 is mounted on a stopped vehicle. The power transmission device 3 may be configured to be movable on the ground side with respect to the received power reception device 4.

DESCRIPTION OF SYMBOLS 1 Non-contact electric power feeding system 10 Power transmission part 12 1st resonance circuit (resonance circuit)
12a Power transmission coil 13 External power supply 15 Control unit 20 Power reception unit 21 Second resonance circuit (resonance circuit)
21a Power receiving coil 30 Notification unit MA Position shift amount

Claims (4)

A power transmission unit having a first resonance circuit including a power transmission coil;
A power receiving unit having a second resonance circuit including a power receiving coil and receiving power from the power transmitting unit in a contactless manner;
A control unit that controls power supply from the power transmission unit to the power reception unit,
The control unit detects a change in a characteristic value related to the power supply that occurs in accordance with a displacement amount between the power transmission coil and the power reception coil, and the power transmission coil and the power reception coil based on the change in the characteristic value The non-contact electric power feeding system which performs the determination control which determines whether the position shift between is an acceptable range.   After the determination control is started, the control unit decreases after the characteristic value reaches a maximum value from a value lower than a range of values that the characteristic value can take when the positional deviation is within an allowable range. 2. The contactless power feeding system according to claim 1, wherein when the characteristic value becomes a threshold value smaller than the maximum value, the positional deviation is determined to be within an allowable range.   The non-contact power feeding system according to claim 1, wherein the characteristic value is a voltage applied to the power receiving unit by the power supply from the power transmitting unit.   The non-contact power feeding system according to any one of claims 1 to 3, further comprising a notification unit that notifies that when the positional deviation is determined to be within the allowable range by the control unit.

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