Ground unit in a wireless charging system

Abstract

To more accurately estimate the height of the receiving coil (vehicle height) when charging. [Solution] In a contactless charging system consisting of a vehicle-side unit and a ground-side unit, the ground-side unit has a vehicle height detection coil that generates impedance corresponding to the height of the receiving coil relative to the planar position of the receiving coil of the vehicle-side unit, and estimates the vehicle height based on the impedance detected by the vehicle height detection coil and the planar position of the receiving coil immediately before charging.

Description

[Technical Field]

[0001] The present disclosure relates to a ground unit in a contactless charging system, and more particularly to a ground unit in a contactless charging system including a vehicle unit mounted on a vehicle and a ground unit that transmits power to the vehicle unit. [Background technology]

[0002] A conventional contactless charging system of this type is proposed that estimates the distance between the power transmitting coil and the power receiving coil in the vehicle height direction from the vehicle height measured by a vehicle height sensor, estimates the distance between the power transmitting coil and the power receiving coil in the planar direction from a coupling coefficient obtained based on the output impedance of a high-frequency power circuit, and calculates the inter-coil distance between the power transmitting coil and the power receiving coil based on the estimated distance in the vehicle height direction and the estimated distance in the planar direction (see, for example, Patent Document 1). In this system, the above-mentioned method is used to more appropriately determine the inter-coil distance between the power transmitting coil of the power transmitting device and the power receiving coil of the power receiving device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2016-086577 Summary of the Invention [Problem to be solved by the invention]

[0004] In a contactless charging system, power is exchanged based on the planar position and height (vehicle height) of the receiving coil relative to the transmitting coil. However, since the vehicle height when the vehicle is parked on the ground unit changes when the occupants exit the vehicle, it is necessary to more accurately detect the vehicle height after exiting in order to exchange power efficiently and charge the battery.

[0005] The main purpose of the ground unit in the contactless charging system of the present disclosure is to more accurately estimate the height of the power receiving coil (vehicle height) during charging. [Means for solving the problem]

[0006] The ground unit in the contactless charging system of the present disclosure employs the following measures to achieve the above-mentioned main object.

[0007] The ground unit in the wireless charging system of the present disclosure includes: A wireless charging system including a vehicle-side unit having a power receiving coil that receives power to charge a battery mounted on a vehicle, and a ground-side unit having a power transmitting coil that transmits power from an external power source to the power receiving coil of the vehicle-side unit, the ground-side unit comprising: a vehicle height detection coil that generates impedance according to the height of the power receiving coil relative to a planar position of the power receiving coil of the vehicle-side unit; a vehicle height estimation device that estimates a vehicle height based on the impedance detected by the vehicle height detection coil and the planar position of the power receiving coil; The present invention is characterized by comprising:

[0008] The ground unit in the wireless charging system disclosed herein has a vehicle height detection coil that generates impedance corresponding to the height of the power receiving coil relative to the planar position of the power receiving coil in the vehicle unit, and estimates the vehicle height based on the impedance detected by the vehicle height detection coil and the planar position of the power receiving coil. Therefore, by estimating the vehicle height after the occupants have exited the vehicle, the height of the power receiving coil (vehicle height) during charging can be more accurately estimated. As a result, power can be efficiently exchanged to charge the battery.

[0009] In the ground unit of the wireless charging system disclosed herein, the vehicle unit may include a planar position estimation device that estimates the planar position of the power receiving coil based on the positions of the power receiving coil and the power transmitting coil, and the vehicle height estimation device may acquire the planar position of the power receiving coil estimated by the planar position estimation device and estimate the vehicle height. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram showing an outline of the configuration of a contactless charging system 10 according to an embodiment of the present disclosure. [Figure 2] 10 is an explanatory diagram showing an example of the relationship between the position (x) in the vehicle longitudinal direction, the vehicle height H, and the impedance Z exhibited by the vehicle height detection coil 134. FIG. [Figure 3] 10 is a flowchart showing an example of a vehicle height estimation process executed by a ground-side electronic control unit 133. DETAILED DESCRIPTION OF THE INVENTION

[0011] Next, a mode (embodiment) for carrying out the present disclosure will be described. Fig. 1 is a configuration diagram showing an outline of the configuration of a contactless charging system 10 according to one embodiment of the present disclosure. The contactless charging system 10 of the embodiment includes a vehicle-side unit 30 mounted on a vehicle 20, and a ground-side unit 120 connected to an external power source 200.

[0012] The vehicle-side unit 30 includes a receiving coil 32, a charging circuit (not shown) for charging a battery (not shown) with the power received by the receiving coil 32, a vehicle-side electronic control unit 33 for controlling the charging of the battery, a communication unit 38, and a vehicle-side antenna 39 connected to the communication unit 38.

[0013] The ground unit 120 includes a power transmission circuit 130 connected to an external power source 200, a power transmission coil 132 connected to the power transmission circuit 130 and placed underground in the parking lot, a ground electronic control unit 133 that controls the power transmission, n vehicle height detection coils 134(1) to 134(n) placed underground in the parking area for charging, a communication unit 138, and a ground antenna 139 connected to the communication unit 138.

[0014] The n vehicle height detection coils 134(1) to 134(n) are configured using well-known foreign object detection coils and are aligned in a matrix (e.g., 4 rows and 3 columns) in the charging parking area. As shown in FIG. 2, which shows the relationship between the position (x) in the vehicle's fore-and-aft direction, the vehicle height H, and the impedance Z exhibited by the vehicle height detection coil 134, each of the n vehicle height detection coils 134(1) to 134(n) changes its impedance Z in response to a change in the position (x) in the fore-and-aft direction of the vehicle. As can be seen from FIG. 2, the impedance Z exhibited by the vehicle height detection coil 134 decreases as the vehicle height H increases, and the higher the vehicle height H, the smaller the change in impedance Z in response to a change in the position (x) in the fore-and-aft direction of the vehicle. In the embodiment, for each of the vehicle height detection coils 134(1) to 134(n), the relationship between the planar position (x, y) of the vehicle relative to the power transmission coil 132 of the ground unit 120, the vehicle height H, and the impedance Z is obtained in advance by experiment or the like to create a vehicle height estimation map, and the map is stored in the ground side electronic control unit 133.

[0015] Next, a description will be given of the operation of the wireless charging system 10 configured as above, in particular the operation of the ground unit 120 when estimating the vehicle height H. Fig. 3 is a flowchart showing an example of a vehicle height estimation process executed by the ground electronic control unit 133. This vehicle height estimation process is executed immediately before the start of power transmission by the power transmitting coil 132.

[0016] When the vehicle height estimation process is executed, the ground electronic control unit 133 first acquires the planar position (x, y) of the vehicle in the parking area for charging (step S100). In the embodiment, the planar position (x, y) of the vehicle in the parking area for charging is detected by the vehicle-side unit 30 and acquired through communication.

[0017] Subsequently, it is determined whether the planar position (x, y) of the vehicle in the parking area for charging is within the allowable range (-xref < x < xref, -yref < y < yref) (step S110). The allowable range (-xref < x < xref, -yref < y < yref) can use, for example, a range in which non-contact charging can be performed relatively efficiently. When it is determined that the planar position (x, y) of the vehicle is not within the allowable range, it is determined that there is no need to estimate the vehicle height H because non-contact charging cannot be performed efficiently, and this process ends.

[0018] When it is determined in step S110 that the planar position (x, y) of the vehicle in the parking area for charging is within the allowable range, the processes of steps S130 to S160 are repeated until the argument i reaches n. In this repeated process, the argument i is incremented (step S130), the impedance Z(i) of the vehicle height detection coil 134(i) is acquired (step S140), the acquired impedance Z(i) of the vehicle height detection coil 134(i) and the planar position (x, y) of the vehicle are applied to the vehicle height estimation map of the vehicle height detection coil 134(i) to derive the vehicle height H(i) (step S150), and it is determined whether the argument n has reached n (step S160). By performing the repeated processes of steps S130 to S160 in this way, n vehicle heights H(1) to H(n) are derived from the n impedances Z(1) to Z(n) detected by the n vehicle height detection coils 134(1) to 134(n).

[0019] Then, the vehicle height H is estimated based on the n vehicle heights H(1) to H(n) (step S170), and this process ends. The vehicle height H can be, for example, the average value of the n vehicle heights H(1) to H(n) as the estimated value, or the median value of the n vehicle heights H(1) to H(n) as the estimated value.

[0020] In the ground unit 120 of the contactless charging system 10 of the embodiment described above, immediately before starting power transmission, the planar position (x, y) of the vehicle in the parking area for charging is acquired, and the n impedances Z(1) to Z(n) detected by the n vehicle height detection coils 134(1) to 134(n) and the planar position (x, y) of the vehicle are applied to the vehicle height estimation map of each vehicle height detection coil 134(1) to 134(n) to derive n vehicle heights H(1) to H(n), and vehicle height H is estimated based on these n vehicle heights H(1) to H(n). This allows for a more accurate estimation of vehicle height H during charging.

[0021] In the ground unit 120 of the contactless charging system 10 of the embodiment, n vehicle heights H(1) to H(n) are derived using n vehicle height detection coils 134(1) to 134(n), and the vehicle height H is estimated based on the n vehicle heights H(1) to H(n), but n may be any number. For example, the vehicle height may be estimated using only a single vehicle height detection coil.

[0022] The correspondence between the main elements of the embodiment and the main elements of the invention described in the "Means for Solving the Problems" section will be described below. In the embodiment, the power receiving coil 32 corresponds to the "power receiving coil," the vehicle-side unit 30 corresponds to the "vehicle-side unit," the power transmitting coil 132 corresponds to the "power transmitting coil," the ground-side unit 120 corresponds to the "ground-side unit," the n vehicle height detecting coils 134(1) to 134(n) correspond to the "vehicle height detecting coils," and the ground-side electronic control unit 133 corresponds to the "vehicle height estimation device."

[0023] The correspondence between the main elements of the embodiments and the main elements of the invention described in the "Means for Solving the Problem" section does not limit the elements of the invention described in the "Means for Solving the Problem" section, since the embodiments are examples for specifically explaining the mode for implementing the invention described in the "Means for Solving the Problem" section. In other words, the interpretation of the invention described in the "Means for Solving the Problem" section should be based on the description in that section, and the embodiments are merely specific examples of the invention described in the "Means for Solving the Problem" section.

[0024] The present disclosure has been described above using embodiments, but the present disclosure is not limited to these embodiments in any way, and it goes without saying that the present disclosure can be embodied in various forms within the scope that does not deviate from the gist of the present disclosure. [Industrial Applicability]

[0025] The present disclosure can be used in the manufacturing industry of contactless charging systems and ground units used therein. [Explanation of symbols]

[0026] 10 Wireless charging system, 20 Vehicle, 30 Vehicle side unit, 32 Power receiving coil, 33 Vehicle side electronic control unit, 38 Communication unit, 39 Vehicle side antenna, 39, 120 Ground side unit, 130 Power transmission circuit, 132 Power transmission coil, 133 Ground side electronic control unit, 134(1) to 134(n) Vehicle height detection coil, 138 Communication unit, 139 Ground side antenna, 200 External power supply.

Claims

[Claim 1] A wireless charging system including a vehicle-side unit having a power receiving coil that receives power to charge a battery mounted on a vehicle, and a ground-side unit having a power transmitting coil that transmits power from an external power source to the power receiving coil of the vehicle-side unit, the ground-side unit comprising: a vehicle height detection coil that generates impedance according to the height of the power receiving coil relative to a planar position of the power receiving coil of the vehicle-side unit; a vehicle height estimation device that estimates a vehicle height based on the impedance detected by the vehicle height detection coil and the planar position of the power receiving coil; A ground unit comprising:

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