JP2024004217A - Contactless charging system - Google Patents

Abstract

[Problem] To improve charging efficiency when a vehicle performs non-contact charging. [Solution] A contactless charging system that charges a battery mounted on a vehicle by transmitting power contactlessly between a power receiving unit installed in a vehicle and a power transmitting unit installed on the ground. During charging, actual measurement information including the transmission efficiency between the power reception unit and the power transmission unit and the relative positional relationship between the power reception unit and the power transmission unit is stored in the storage unit, and the actual measurement information stored in the storage unit is The vehicle position with high transmission efficiency is calculated using the above-described method, and the calculated vehicle position is set as the target parking position. [Selection diagram] Figure 5

Description

The present invention relates to a contactless charging system.

Patent Document 1 describes a non-contact charging system that includes a power transmission coil on the ground side and a power reception coil on the vehicle side, in which a position with the best transmission efficiency is searched for while the vehicle is parked in a power supply space, and the vehicle is placed at that position. It is disclosed that the driver is notified that the vehicle has moved.

Japanese Patent Application Publication No. 2017-093129

In the configuration described in Patent Document 1, the position with the best transmission efficiency is set to the position where the positional differential value of the transmission efficiency is zero. However, even if the positional differential value of the transmission efficiency becomes zero, that is, the local maximum value is detected, when there are multiple local maximum values, the first detected local maximum value is not necessarily the maximum value of the transmission efficiency. Therefore, it may be difficult to park at a position where transmission efficiency is maximized.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a contactless charging system that can improve charging efficiency when a vehicle performs contactless charging.

The present invention is a non-contact charging system that non-contactly transmits power between a power receiving unit provided on a vehicle and a power transmitting unit provided on the ground to charge a battery mounted on the vehicle. During contact charging, actual measurement information including transmission efficiency between the power receiving unit and the power transmitting unit and a relative positional relationship between the power receiving unit and the power transmitting unit is stored in a storage unit; The present invention is characterized in that the vehicle position with high transmission efficiency is calculated using the stored actual measurement information, and the calculated vehicle position is set as the target parking position.

In the present invention, since a position with high transmission efficiency is set as a target parking position using actual measurement information acquired during non-contact charging, charging efficiency can be increased by parking the vehicle at the target parking position.

FIG. 1 is a diagram schematically showing a non-contact charging system in an embodiment. FIG. 2 is a diagram for explaining positional deviation in the front-rear direction. FIG. 3 is a diagram for explaining the position detection method. FIG. 4 is a flowchart showing a control flow of non-contact charging. FIG. 5 is a flowchart showing the calculation flow of the target parking position. FIG. 6 is a flowchart showing the flow of creating a transmission efficiency database. FIG. 7 is a diagram showing the structure of the transmission efficiency database.

EMBODIMENT OF THE INVENTION Hereinafter, with reference to drawings, the non-contact charging system in embodiment of this invention is demonstrated concretely. Note that the present invention is not limited to the embodiments described below.

FIG. 1 is a diagram schematically showing a non-contact charging system in an embodiment. The non-contact charging system 1 includes a power transmission unit 10 provided on the ground and a power reception unit 20 provided in the vehicle 2. The non-contact charging system 1 charges the driving battery 30 of the vehicle 2 with electric power transmitted from the power transmitting unit 10 to the power receiving unit 20 in a non-contact manner when the vehicle 2 is parked in a parking space where the power transmitting unit 10 is installed. It is a system that The vehicle 2 is an electric vehicle equipped with a driving motor, and includes a power receiving unit 20, a driving battery 30, a charging control section 40, and a transmission efficiency database 50. The vehicle 2 is an electric vehicle that can be externally charged by non-contact power supply.

The power transmission unit 10 is a contactless charging ground unit (GA) equipped with a power transmission coil 11 for transmitting electric power. As shown in FIG. 2, the power transmission unit 10 is provided in a parking space such as a non-contact charging station 3. The power transmission unit 10 includes a power transmission coil 11 , a first radio device 12 , a first control section 13 , a first power detection section 14 , and a position detection section 15 .

The power transmission coil 11 is a coil for contactless power transmission provided on the ground. The power transmitting coil 11 performs contactless power transmission with a power receiving coil 21 mounted on the vehicle 2. Power transmission coil 11 is supplied with power from the grid.

The first radio device 12 is a radio device for performing data communication with the power receiving unit 20. The first radio device 12 performs wireless communication with a second radio device 22 mounted on the vehicle 2. When the first radio device 12 and the second radio device 22 transmit and receive information through wireless communication, the power transmission unit 10 on the ground side and the power reception unit 20 on the vehicle side perform data communication.

The first control unit 13 controls contactless power transmission from the power transmission coil 11 on the ground side to the power reception coil 21 on the vehicle side. The first control unit 13 controls the start and end of non-contact charging in response to a command signal from the power receiving unit 20. This command signal is received by the first radio device 12. The first control unit 13 controls the power transmission coil 11 based on the command signal received by the first radio device 12 .

The first power detection unit 14 detects the power transmitted by the power transmission coil 11 in a non-contact manner. The first power detection unit 14 detects the power transmitted from the start to the end of non-contact charging, that is, during charging (transmitted power).

The position detection unit 15 is a position detection system that can detect a longitudinal positional deviation and a lateral positional deviation between the center position of the power receiving unit 20 on the vehicle side and the center position of the power transmission unit 10 on the ground side. As a position detection method, for example, as shown in FIG. 3, a plurality of LEDs 25 attached to the power receiving unit 20 on the vehicle side are photographed by a camera 16 attached to the power transmitting unit 10 on the ground side, and the center position of the power transmitting unit 10 is detected. There is a method of calculating the distance between the center position of the power receiving unit 20 and the center position of the power receiving unit 20. In this case, the position detection unit 15 is configured to include a camera 16 disposed at the center position of the power transmission unit 10 in the longitudinal direction and the lateral direction. The power receiving unit 20 is configured to include two rows of LEDs 25 provided on both sides in the vehicle width direction and arranged side by side in the vehicle longitudinal direction.

For example, as shown in FIG. 2, the position detection unit 15 detects the positional deviation of the center position of the power receiving unit 20 on the vehicle side with respect to the center position of the power transmission unit 10 on the ground side as the positional deviation in the front-rear direction. When the position detection unit 15 detects a positional deviation between the power transmission unit 10 and the power reception unit 20, it outputs a signal indicating the amount of positional deviation to the first control unit 13. The first control unit 13 obtains the amount of positional deviation in the front-rear direction and the amount of positional deviation in the lateral direction between the power transmission unit 10 and the power reception unit 20 based on the signal from the position detection unit 15. This positional shift amount information represents the relative positional relationship between the power receiving unit 20 and the power transmitting unit 10.

Further, the power transmission unit 10 is given a serial number which is an individual identifier. For example, the non-contact charging station 3 is provided with a plurality of parking spaces, and each parking space is provided with a power transmission unit 10. During non-contact charging, the power transmitting unit 10 transmits information including the serial number, which is an identifier, to the power receiving unit 20 by wireless communication.

The power receiving unit 20 is a non-contact charging vehicle unit (VA) including a power receiving coil 21 for receiving electric power. As shown in FIG. 2, the power receiving unit 20 is provided at the bottom of the vehicle 2. The power reception unit 20 includes a power reception coil 21 , a second radio 22 , a second control section 23 , and a second power detection section 24 .

The power reception coil 21 is a coil for non-contact power reception mounted on the vehicle 2, and is provided at the lower part of the vehicle 2. The power receiving coil 21 receives power transmitted from the power transmitting coil 11 in a non-contact manner. The vehicle 2 charges the driving battery 30 with the power received by the power receiving coil 21.

The second radio device 22 is a radio device for performing data communication with the power transmission unit 10. The second radio device 22 performs wireless communication with the first radio device 12 provided in the power transmission unit 10.

The second control unit 23 executes control such that the power receiving coil 21 on the vehicle side receives electric power transmitted in a non-contact manner from the power transmitting coil 11 on the ground side. The second control unit 23 controls the start of non-contact charging and the end of non-contact charging. The second control unit 23 executes communication control to cause the second radio device 22 to transmit a command signal for controlling the start and end of non-contact charging to the first radio device 12, and also controls the power receiving coil 21. . In the non-contact charging system 1, a control unit including a first control unit 13 and a second control unit 23 is configured to control power transmission between the power transmission unit 10 on the ground side and the power reception unit 20 on the vehicle side. has been done.

The second power detection unit 24 detects the power received by the power receiving coil 21 in a non-contact manner. The second power detection unit 24 detects the power received from the start to the end of non-contact charging, that is, during charging (received power).

The driving battery 30 supplies electric power to a driving motor mounted on the vehicle 2. The driving battery 30 is constituted by a secondary battery that can store electric power to be supplied to the driving motor.

The charging control unit 40 executes charging control to charge the driving battery 30 with the power received by the power receiving coil 21. Further, the charging control unit 40 functions as a control unit for determining the start and end of non-contact charging. A signal from the second control section 23 is input to the charging control section 40 . The charging control unit 40 can determine whether to start non-contact charging based on the signal from the second control unit 23, and can also determine whether to end non-contact charging.

The charging control unit 40 also calculates the transmission efficiency during non-contact charging. The charging control section 40 is configured to include a transmission efficiency calculation section that calculates transmission efficiency. The transmission efficiency is the ratio of the power received by the power receiving coil 21 to the power transmitted by the power transmitting coil 11. Both powers were actually measured during non-contact charging. The transmitted power is an actual value detected by the first power detection unit 14 during charging. The received power is an actual value detected by the second power detection unit 24 during charging.

Information on the transmitted power detected by the first power detection section 14 is input from the first power detection section 14 to the first control section 13, and is transmitted from the first radio device 12 to the second radio device 22 on the vehicle side. Ru. When the second radio device 22 receives the signal from the first radio device 12, the charging control unit 40 can acquire information on the transmitted power.

Information on the received power detected by the second power detection section 24 is input from the second power detection section 24 to the second control section 23 and transmitted from the second control section 23 to the charging control section 40 . The second control section 23 and the charging control section 40 are communicably connected via a CAN communication line 60. The second control unit 23 transmits information on the transmitted power received by the second radio device 22 to the charging control unit 40 . The charging control unit 40 obtains information on received power and information on transmitted power by receiving a signal from the second control unit 23 .

Then, the charging control unit 40 stores the transmission efficiency calculated by the transmission efficiency calculation unit in the transmission efficiency database 50. At this time, the charging control unit 40 stores the transmission efficiency calculated at the time of charging and the positional deviation amount detected by the position detection unit 15 at the time of charging as a set in the database. The charging control unit 40 stores this information every time charging is performed, and the acquired data group is referred to as a transmission efficiency database 50. That is, the charging control unit 40 stores actual measurement information including the transmission efficiency and the amount of positional deviation in the transmission efficiency database 50 during non-contact charging.

The transmission efficiency database 50 is a storage unit that stores actually measured power transmission efficiency (=transmission efficiency). Since transmission efficiency depends on the power transmission unit 10, when storing transmission efficiency information in the transmission efficiency database 50, the serial number of the power transmission unit 10 is checked, and a database is created for each serial number. Furthermore, since the transmission efficiency also depends on the charging rate (SOC) of the drive battery 30, when storing transmission efficiency information in the transmission efficiency database 50, a database is created for each SOC.

In the non-contact charging system 1 configured in this way, the target parking position is the position where the transmission efficiency is maximized (the maximum transmission efficiency position), which is estimated based on the power transmission efficiency in the longitudinal direction and the lateral direction of the vehicle, which has been actually measured in advance. do. The charging control unit 40 sets the position with the highest transmission efficiency in the transmission efficiency database 50 or the position with the highest transmission efficiency determined by interpolation processing as the maximum transmission efficiency position. The charging control unit 40 sets the set maximum transmission efficiency position as the target parking position. That is, when the vehicle 2 parks at the non-contact charging station 3, the parking position where the transmission efficiency is maximum is calculated from the power transmission efficiency data measured in advance, and the calculated position is set as the target parking position. . This makes it possible to maximize charging efficiency.

Here, a control configuration implemented by the control unit of the non-contact charging system 1 will be explained.

First, with reference to FIG. 4, the flow from the start to the end of non-contact charging control will be described. FIG. 4 is a flowchart showing a control flow of non-contact charging.

The control unit of the non-contact charging system 1 activates the position detection system when parking, and detects the amount of positional deviation between the power receiving unit 20 and the power transmitting unit 10 (step S11). In step S11, the position detection section 15 is activated in response to a command signal from the second control section 23 through data communication between the power reception unit 20 and the power transmission unit 10, and the position detection section 15 is activated in response to a command signal from the second control section 23, and the position detection section 15 detects a longitudinal positional deviation of the power reception unit 20 with respect to the power transmission unit 10. amount and the amount of lateral displacement are detected.

The vehicle is automatically or manually parked toward the target parking position (step S12). In step S12, the target parking position calculated based on the transmission efficiency stored in the transmission efficiency database 50 is used. In the case of automatic parking, the vehicle 2 is automatically parked at the target parking position by automatic driving control. In the case of manual parking, the target parking position is displayed on an instrument panel or the like to notify the driver, and the vehicle is manually parked at the target parking position in accordance with the driver's operation.

After parking is completed, it is determined that the positional deviation amount is less than or equal to the positional deviation allowable value (step S13). In step S13, it is determined that the positional deviation amount of the center position of the power receiving unit 20 with respect to the center position of the power transmission unit 10 is equal to or less than the positional deviation tolerance value in a state where the vehicle 2 is parked. The positional deviation tolerance value is a predetermined value set in advance. The positional deviation tolerance value can be used as a tolerance value for the amount of positional deviation in the front-rear direction and a tolerance value for the amount of positional deviation in the lateral direction. In this case, the positional deviation tolerance value may be set to the same value in the front-rear direction and the lateral direction, or the positional deviation tolerance value may be set to a different value in the front-rear direction and the lateral direction. If it is determined that the positional deviation amount after parking is completed is larger than the positional deviation tolerance value, this control routine does not proceed to step S14, and it is determined that the parking position has deviated from the target parking position by more than the tolerance value. It is possible to notify the driver, etc., and then return to step S11.

If it is determined that the amount of positional deviation after parking is completed is less than or equal to the permissible positional deviation value, the control unit of the non-contact charging system 1 supplies current to the power transmission coil 11 on the ground side and starts non-contact charging (step S14). In step S14, the charging control unit 40 on the vehicle side determines that non-contact charging has started. In step S14, the first power detection unit 14 starts measuring the transmitted power, and the second power detection unit 24 starts measuring the received power. Furthermore, supply of the power received by the power receiving coil 21 to the driving battery 30 is started.

Then, the charging of the driving battery 30 progresses and it is determined that it is fully charged (step S15). In step S15, it is determined whether the drive battery 30 is fully charged based on the SOC. The charging control unit 40 calculates the SOC of the driving battery 30 based on a signal input from a current sensor that detects the current flowing through the driving battery 30. Then, the charging control unit 40 determines that the driving battery 30 is fully charged when the SOC increases during charging and reaches the SOC (threshold value) indicating that the battery is fully charged. The charging control unit 40 ends the charging when it is determined that the non-contact charging progresses smoothly and the battery is fully charged. After executing the process of step S15, this control routine ends.

Next, a method for calculating the target parking position will be described with reference to FIG. 5. FIG. 5 is a flowchart showing the calculation flow of the target parking position.

The charging control unit 40 checks the serial number of the power transmission unit 10 and the current SOC of the drive battery 30, and sets a predetermined number of data in the transmission efficiency database 50 that match the serial number and the current SOC. It is determined whether or not it is the above (step S21). In step S21, when the vehicle 2 parks at the non-contact charging station 3, the serial number information transmitted from the power transmission unit 10 and the current SOC information calculated by the charging control unit 40 are used to It is checked how many pieces of data that match the information exist in the transmission efficiency database 50. If the number of data matching the serial number and the current SOC is greater than or equal to a predetermined value, the charging control unit 40 determines that the estimation accuracy of the maximum transmission efficiency position has been secured at a certain level or higher, and the control routine moves to step S22. do. On the other hand, if the condition is not satisfied, the control routine moves to step S24.

If it is determined that the number of data that matches the serial number and the current SOC is greater than or equal to the predetermined value (step S21: Yes), the charging control unit 40 uses the data stored in the transmission efficiency database 50 to maximize the transmission efficiency. The position is calculated (step S22). The maximum transmission efficiency position is the position in the transmission efficiency database 50 that has the highest transmission efficiency. Alternatively, the maximum transmission efficiency position may be determined by interpolating the amount of positional deviation in the longitudinal and lateral directions.

The charging control unit 40 sets the maximum transmission efficiency position calculated in step S22 as the target parking position (step S23). After carrying out the process of step S23, this control routine ends.

If it is determined that the number of data that matches the serial number and the current SOC is less than the predetermined value (step S21: No), the charging control unit 40 selects the position where the transmission efficiency is maximum (transmission efficiency maximum position) based on the design. design value) is set as the target parking position (step S24). If the number of data stored in the transmission efficiency database 50 is not sufficient, there is a concern that the accuracy of the maximum transmission efficiency position may be insufficient, so this is not set as the target parking position. In this case, in step S24, the position at which the transmission efficiency is maximized (the maximum transmission efficiency position design value) estimated using the design value is set as the target parking position. The maximum transmission efficiency position design value is, for example, a position where the amount of positional deviation in the longitudinal direction is zero and the amount of positional deviation in the lateral direction is zero. After executing the process of step S24, this control routine ends.

Next, a method for creating a data group to be stored in the transmission efficiency database 50 will be described with reference to FIG. 6. FIG. 6 is a flowchart showing the flow of creating a transmission efficiency database. The control shown in FIG. 6 is performed by the charging control section 40.

The charging control unit 40 determines whether non-contact charging has been started (step S31). In step S31, it is determined whether or not non-contact power transmission from the power transmitting coil 11 to the power receiving coil 21 has been started while the vehicle 2 is parked.

If it is determined that non-contact charging has not been started (step S31: No), this control routine ends. Since the transmission efficiency stored in the transmission efficiency database 50 is actually measured during charging, the process ends if charging has not started.

When it is determined that non-contact charging has started (step S31: Yes), the charging control unit 40 calculates the transmission efficiency (step S32). In step S32, the ratio of the power received by the power receiving coil 21 to the power transmitted by the power transmitting coil 11 is calculated as the transmission efficiency.

Then, the charging control unit 40 associates the transmission efficiency calculated in step S32 with the amount of positional deviation in the longitudinal direction and the amount of positional deviation in the lateral direction, the serial number of the power transmission unit 10, and the current SOC and databases the transmission efficiency. 50 (step S33). In step S33, the amount of displacement in the longitudinal direction and the amount of displacement in the lateral direction, the serial number of the power transmission unit 10 in use, and the current SOC of the drive battery 30 are acquired. Then, for each of these states, the transmission efficiency calculated in step S32 is stored in the transmission efficiency database 50. That is, actual measurement information including at least the transmission efficiency and the amount of positional deviation is stored in the transmission efficiency database 50. If previously acquired data has already been stored, as shown in FIG. 7, averaging processing is performed including the currently acquired data, and the data is stored together with the number of data. This processing is not limited to averaging processing, and calculation may be performed by increasing the reflection rate of the latest data. After executing the process of step S33, this control routine ends.

As explained above, according to the embodiment, it is possible to park at a position where charging efficiency is maximized. In the non-contact charging system 1, since the maximum charging efficiency is predicted by interpolation instead of extrapolation as in the conventional technology, charging efficiency can be improved. In addition, in the non-contact charging system 1, the charging efficiency can be improved because the transmission efficiency in the lateral direction as well as in the front-rear direction of the power transmission unit 10 on the ground side is taken into consideration. Moreover, in the non-contact charging system 1, when actually measuring the transmission efficiency, the charging efficiency is measured not while the vehicle 2 is moving but while the vehicle 2 is stopped.

Furthermore, the influence of factors that influence transmission efficiency can be excluded, increasing the accuracy of estimating the position of maximum transmission efficiency. Furthermore, deterioration in the estimation accuracy of the maximum transmission efficiency position due to insufficient data in the transmission efficiency database 50 can be avoided.

1 Non-contact charging system 2 Vehicle 10 Power transmission unit 11 Power transmission coil 12 First radio device 13 First control section 14 First power detection section 15 Position detection section 20 Power receiving unit 21 Power receiving coil 22 Second radio device 23 Second control section 24 Second power detection section 30 Driving battery 40 Charging control section 50 Transmission efficiency database

Claims (1)

A contactless charging system that charges a battery mounted on the vehicle by transmitting power in a non-contact manner between a power reception unit installed on a vehicle and a power transmission unit installed on the ground,
During non-contact charging, actual measurement information including transmission efficiency between the power receiving unit and the power transmitting unit and a relative positional relationship between the power receiving unit and the power transmitting unit is stored in a storage unit;
A non-contact charging system, characterized in that the vehicle position with high transmission efficiency is calculated using the measured information stored in the storage unit, and the calculated vehicle position is set as a target parking position.

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