Vehicle charging device and vehicle charging method

Abstract

To provide a vehicle charging device and a vehicle charging method in which a charging abnormality due to poor communication quality is effectively improved.SOLUTION: In a vehicle charging system 90, a vehicle charging device 9A connected to a cloud computing platform 9D via a network 9C includes a transformer 91 and two impedance tuners 92, two communication lines 93 are disposed on one side of the transformer so as to be connected to an electric automobile 9B, and each of the two impedance tuners is connected in parallel with one of the two communication lines. Each impedance tuner includes at least one branch path 921 for adjusting a reactance property of each of the communication lines. Therefore, the impedance of each communication line can be stepwisely adjusted in accordance with the signal intensity of the communication line, the vehicle charging device and the electric automobile mutually communicate with each other in a state where impedance matching therebetween is almost achieved, and a charging abnormality caused by an excessively high bit error rate of data exchange is avoided.SELECTED DRAWING: Figure 9

Description

Technical Field

[0001] The present invention relates to charging communication technology, and particularly to a vehicle charging device and a vehicle charging method.

Background Art

[0002] As the awareness of environmental protection increases, electric vehicles and related infrastructures have become increasingly popular. When charging a vehicle, the electric vehicle and the charging stand can be connected to each other. When the charging communication operation between the electric vehicle and the charging stand is completed, the charging stand supplies power to the battery of the electric vehicle.

[0003] During the charging communication operation, if the bit error rate of data exchange is too high, abnormalities such as the inability of the electric vehicle to charge or the interruption of charging may occur. Conventionally, there are several technical means for charging control, but there is still a need for improvement.

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of the present invention is to provide a vehicle charging device and a vehicle charging method that can effectively improve charging abnormalities caused by poor communication quality.

[0005] To achieve the above object, one aspect of the present invention provides a vehicle charging device including a transformer having a first side and a second side, and two communication lines provided on the second side so as to be connected to an electric vehicle, and two impedance tuners each connected in parallel to one of the two communication lines and configured to adjust the reactance characteristics of the two communication lines.

[0006] To achieve the above objective, one aspect of the present invention provides a vehicle charging method applicable to a vehicle charging device, the vehicle charging device comprising: a transformer having a first side and a second side, the second side having two communication lines connected to an electric vehicle; and two impedance tuners, each connected in parallel to one of the two communication lines and configured to adjust the reactance characteristics of the two communication lines, the vehicle charging method comprising: detecting that two communication lines connected to the vehicle charging device are connected to an electric vehicle; the vehicle charging device communicating with the electric vehicle via power lines, the vehicle charging device collecting signal strengths of multiple signal channels of the electric vehicle; the vehicle charging device monitoring the communication characteristics of the two communication lines based on the signal strengths of the multiple signal channels so that the signal strengths of the two communication lines meet strength requirements; and the vehicle charging device entering a charging mode for the electric vehicle in response to the signal strengths of the two communication lines meeting strength requirements. [Effects of the Invention]

[0007] The vehicle charging device and vehicle charging method of the present invention are configured such that the second side of the transformer of the vehicle charging device is provided with two communication lines (having capacitors) to be connected to an electric vehicle, each of the impedance tuners of the vehicle charging device is connected in parallel to one of the communication lines, and the two impedance tuners are configured to adjust the reactance characteristics of the two communication lines, for example, each of the two impedance tuners includes at least one branch path (including a switch and a capacitor), and each of the at least one branch path is connected in parallel to the capacitor of the communication line. Therefore, depending on the signal strength of the communication line, the connection between an appropriate number of branch path capacitors and the capacitor of the communication line can be controlled in stages, and by adjusting the impedance of the communication line, the vehicle charging device and the electric vehicle can communicate with each other in a state that approaches impedance matching, and abnormalities such as the electric vehicle being unable to charge or charging being interrupted due to a high bit error rate in data exchange can be avoided. [Brief explanation of the drawing]

[0008] [Figure 1] Figure 1 is a schematic diagram of a vehicle charging system to which an embodiment of the present invention can be applied. [Figure 2] Figure 2 is a schematic diagram of the first signal transmission mode of the vehicle charging system shown in Figure 1. [Figure 3] Figure 3 is a schematic diagram of the power spectral density distribution of the communication line in the example of the first charging station shown in Figure 2. [Figure 4] Figure 4 is a schematic diagram of the power spectral density distribution of the communication line in the example of the second charging station shown in Figure 2. [Figure 5] Figure 5 is a schematic diagram of the second signal transmission mode of the vehicle charging system shown in Figure 1. [Figure 6] Figures 6(a) and 6(b) are schematic diagrams of the equivalent circuit and insertion loss in the example of the first charging station shown in Figure 5. [Figure 7] Figures 7(a) and 7(b) are schematic diagrams of the equivalent circuit and insertion loss in the example of the second charging station shown in Figure 5. [Figure 8] Figure 8 is a schematic diagram showing how to acquire the signal strength of multiple signal channels in an example of multiple charging stations shown in Figure 1. [Figure 9] Figure 9 is a schematic block diagram of a vehicle charging device according to an embodiment of the present invention. [Figure 10] Figure 10 is a schematic diagram of the connection configuration between the switch and capacitor in the branching path shown in Figure 9. [Figure 11] Figure 11 is a flowchart of a vehicle charging method according to an embodiment of the present invention. [Modes for carrying out the invention]

[0009] To make the contents of the present invention, as well as other objectives, features, and advantages, clearer and easier to understand, preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0010] As shown in Figure 1, in a vehicle charging system 10 (for example, a Combined Charging System (CCS)), a charging station (Electric Vehicle Supply Equipment, EVSE) 11 and an electric vehicle (Electric Vehicle, EV) 12 can be interconnected. For example, the electric vehicle 12 may include scooter-type vehicles or automobiles. The charging connector of the charging station 11 and the inlet of the electric vehicle 12 form a coupler connection (connector connection). Once the electric vehicle 12 and the charging station 11 complete their charging communication operation, the charging station 11 supplies power to the battery of the electric vehicle 12. If the controller 13 lacks an effective compatibility control or optimization mechanism, such as adjusting for differences in couplers formed by different charging connectors (e.g., different wire lengths or diameters), when the coupler is connected, the bit error rate (BER) of data exchange may be too high, resulting in insufficient adaptability for data communication compatibility. This can lead to abnormalities such as the electric vehicle being unable to charge or charging being interrupted, as the charging communication operation cannot be completed, resulting in an unsatisfactory user experience.

[0011] For example, taking the Power Line Communication (PLC) protocol as an example, during charging communication operation, the communication mode between the charging station and the electric vehicle may be a full-duplex mode that enables simultaneous bidirectional data transmission between the charging station and the electric vehicle.

[0012] As shown in Figure 2, in the first signal transmission mode, the vehicle charging system 20 transmits signals to the electric vehicle 22 via the communication line 23 using a transformer 212 with signal lines (e.g., TXOUT_P and TXOUT_N). For example, the communication line 23 may consist of a control pilot line CP and a protective earth line PE. In this case, if the impedance of the charging station 21 and the electric vehicle 22 is not matched, the signal will be attenuated during communication. For example, the charging station 21 can acquire the signal strength of multiple signal channels between the charging station 21 and the electric vehicle 22 in a sweeping manner so that the charging station 21 can easily acquire the power spectral density profile (PSD profile) of a particular signal.

[0013] In one application example, Figure 3 shows an example PSD profile curve 30 of a communication line (e.g., CP) acquired by the 9th channel (CH9) of a charging station controller, where the signal strength is almost below -40 dBm, for example, the signal strength at sampling point M1 is -43.01 dBm. In another application example, Figure 4 shows an example PSD profile curve 40 of a communication line (e.g., CP) acquired by a controller of a different charging station, where the signal strength is not below -40 dBm at all, for example, the signal strength at sampling point M1 is -45.71 dBm. There is a difference of approximately 6 dB in the signal strength of the two charging stations shown in Figures 3 and 4.

[0014] As shown in Figure 5, in the second signal transmission mode, the vehicle charging system 50, specifically the controller 511 of the charging station 51, receives signals from the electric vehicle 52 via the communication line 53 using signal lines (e.g., RXIN_P and RXIN_N) and a bandpass filter (RX_BPF) 513 and a transformer 512. For example, the communication line 53 may be a control pilot line (CP) and a protective earth line (PE). In this case, if the impedances of the charging station 51 and the electric vehicle 52 are not matched, the signal will be attenuated during communication.

[0015] For example, the insertion loss of the communication lines (e.g., CP and PE) of a coupler circuit can be obtained by the bidirectional channel (e.g., CH57) of the transceiver. Figures 6(a) and 6(b) show an equivalent circuit example 60a and an insertion loss curve example 60b of a charging station, respectively. Insertion loss curve example 60b shows that the insertion loss (S21) of equivalent circuit example 60a in the frequency band of 150kHz (kHz) to 30MHz (MHz) is approximately -20.49dB. Figures 7(a) and 7(b) show an equivalent circuit example 70a and an insertion loss curve example 70b of another charging station, respectively. Insertion loss curve example 70b shows that the insertion loss (S21) of equivalent circuit example 70a in the frequency band of 150kHz to 30MHz is approximately -25.17dB. There is a difference of approximately 5dB in the insertion losses of the two charging stations shown in Figures 6(b) and 7(b).

[0016] Figure 8 shows example signal strength curves 80 for multiple signal channels (e.g., carrier channels CH0 to CH57) acquired from multiple charging stations. All three curves C1, C2, and C3 show a tendency for signal strength to attenuate as the frequency of the carrier channel (CHx, x=0 to 57) increases, with approximately two-thirds of the channels having a signal strength of less than -31 dB, and the received signal strength profile values ​​(e.g., CH57) for the communication line (e.g., CP) of the coupler circuit being approximately -60 dB to -66 dB (lower than the range of -20 dB to -39 dB).

[0017] As can be seen from the above, during charging communication, the charging station and the electric vehicle communicate with each other via two communication lines (e.g., CP and PE). If an impedance mismatch occurs between the charging station and the electric vehicle, the signal will be attenuated during communication, preventing the communication operation from being completed, and potentially causing charging abnormalities.

[0018] For example, in this specification, power line communication (PLC) is used as the charging communication technology based on, for example, the ISO-15118-3 / IEC-61851-1 standard. In a charging stand, the two communication lines are the control pilot line (CP) and the protective earth line (PE). The two communication lines each have capacitance characteristics, and this capacitance characteristic is an important factor affecting the charging communication operation. The reason is at least that since the charging stand needs to supply power to electric vehicles of different manufacturers, the impedance states of each electric vehicle are different.

[0019] Therefore, in order to avoid impedance mismatches between the charging stand and the electric vehicle, the charging stand needs to have a communication impedance adjustment ability to match electric vehicles in different impedance states. When the charging stand and the electric vehicle are connected to form a coupler, the impedances of the charging stand and the electric vehicle on both sides of the coupler tend to match, avoiding severe signal attenuation caused by impedance mismatches and facilitating the completion of the charging communication operation.

[0020] As described above, the present invention provides an implementation method. For example, during the charging communication operation, the charging stand and the electric vehicle communicate with each other via two communication lines (for example, CP and PE), and for a control method in which the communication lines (for example, CP and PE) operating in an open loop form a coupler, a control method in which the communication lines (for example, CP and PE) adjust the impedance (Impedance Tuning) can be adopted. Examples are shown below, but are not limited thereto.

[0021] For example, based on the characteristics of the communication line itself, the communication line impedance adjustment method may be a method that adjusts the reactance characteristics (including inductive reactance and capacitive reactance) of the communication line, and when the charging station and the electric vehicle form a coupler connection state and enter data transmission mode, the signal strength of the communication line (e.g., CP and PE) is acquired via a specific method (e.g., the controller scans a specific channel or executes a specific command). Specifically, the controller of the charging station sends a command called "CM_ATTEN_CHAR.IND" and acquires the "ATTEN_PROFILE" content as signal attenuation profile information. This allows for the rapid acquisition of the signal characteristics of the communication line.

[0022] As a result, the present invention can provide a control method for adjusting its own impedance to facilitate data transmission mode (or diagnostic adjustment procedure), and the coupler formed by the charging station and electric vehicle has the function of detecting communication lines (e.g., CP and PE) in a closed loop and adjusting the impedance, thereby improving data transmission quality and further avoiding situations where communication operations cannot be completed due to signal attenuation during communication, or charging abnormalities.

[0023] In one embodiment, after relevant data has been collected, it is advantageous to use it to understand impedance matching information of communication lines (e.g., CP and PE) of different electric vehicles, evaluate the characteristics of communication lines applicable to different vehicles, create charging impedance adjustment methods applicable to different vehicles, improve charging compatibility and adaptability, and achieve the effect of optimizing the vehicle charging process.

[0024] The present invention provides methods for carrying out the invention based on the above technical means, and examples are given below, but are not limited thereto.

[0025] On the other hand, as shown in Figure 9, an embodiment of the present invention provides a vehicle charging device in which, for example, in a vehicle charging system 90 (e.g., CCS), the vehicle charging device 9A and an electric vehicle 9B are interconnected, and the vehicle charging device 9A may be configured to form a charging station for a vehicle (e.g., a scooter or an automobile), and includes a transformer 91 and two impedance tuners 92.

[0026] For example, as shown in Figure 9, the transformer 91 has a first side and a second side, and the first side of the transformer 91 can transmit and receive signals from electronic equipment via signal lines (e.g., SPI_TX+ and SPI_TX-) and receive signal lines (e.g., SPI_RX+ and SPI_RX-) of a Serial Peripheral Interface (SPI). The first side of the transformer 91 can receive signals from a controller (e.g., a power line communication chipset (PLC chipset), see 211 in Figure 2 and 511 in Figure 5), and the controller can collect signal strengths of multiple signal channels as a reference for communication and control, and the second side of the transformer 91 is provided with two communication lines 93 for connecting an electric vehicle 9B.

[0027] For example, as shown in Figure 9, each of the two impedance tuners 92 is connected in parallel to one of the two communication lines 93, and the two impedance tuners 92 are configured to adjust the reactance characteristics of the two communication lines 93. For example, each impedance tuner 92 may include at least one branch path 921 for adjusting the reactance characteristics of the communication lines 93, as will be described later.

[0028] For example, as shown in Figure 9, each communication line 93 has a first capacitor 94, and each impedance tuner 92 includes at least one branch path 921 connected in parallel to the first capacitor 94. For example, each branch path 921 includes a switch 95 and a second capacitor 96, with the switch 95 and the second capacitor 96 connected in series. The switch 95 for each branch path 921 is configured to form a parallel circuit or an open circuit with the first capacitor 94 and the second capacitor 96 in response to a control signal from a controller (e.g., a PLC chipset), thereby gradually adjusting (e.g., increasing or decreasing) the number of second capacitors 96 connected in parallel to the first capacitor 94 to adjust the equivalent capacitance value of the communication line 93 from 10nF to 20nF, etc., but is not limited to these configurations.

[0029] As shown in Figure 9, the more times the switches 95 of the branch path 921 are turned ON, the more second capacitors 96 that form a parallel circuit with the first capacitor 94 are formed, the larger the equivalent capacitance value of the communication line 93 becomes, and the higher the equivalent capacitance impedance (ZC) of the communication line 93 becomes. Conversely, the fewer times the switches 95 of the branch path 921 are turned ON, the fewer second capacitors 96 that form a parallel circuit with the first capacitor 94 are formed, the smaller the equivalent capacitance value of the communication line 93 becomes, and the lower the equivalent capacitance impedance (ZC) of the communication line 93 becomes. Therefore, the vehicle charging device 9A can control the number of second capacitors 96 that form a parallel circuit with the first capacitor 94 using the switches 95 for each branch path 921 as a reference for adjusting the reactance characteristics of the communication line 93 according to the signal strength of the communication line 93.

[0030] When adjusting the impedance state of a communication line, since the signal frequency of the communication line is relatively high (for example, in the frequency band of 150kHz to 30MHz), the signal frequency of the communication line must be considered when selecting a switch in order to adjust the impedance state of the communication line in immediate response to the signal strength of the communication line. Here, we will explain using the example of an impedance tuner that includes one branch path, but it is not limited to this.

[0031] As shown in Figure 10, the vehicle charging system 100 includes a vehicle charging device 10A and an electric vehicle 10B, the vehicle charging device 10A includes a transformer 101 and two impedance tuners 102, each of which is connected in parallel to one of the two communication lines 103, each of which has a first capacitor 104, and each of the impedance tuners 102 includes at least one branch path 1021 (only one branch path 1021 is shown in Figure 10). For example, each of the branch paths 1021 includes a switch 105 and a second capacitor 106, the switch 105 may be a high-frequency switching element, for example, the operating frequency range of the switch 105 includes, but is not limited to, 150kHz to 30MHz.

[0032] As shown in Figure 10, in order to ensure the switching speed of the switch and avoid signal interference, etc., the switch 105 may be a chip type switch. For example, the chip type switch has a control terminal CTL and two connection terminals CN1 and CN2, and a second capacitor 106 is connected between one of the two connection terminals CN1 and CN2 (e.g., CN1) and one end of the first capacitor 104, and the other of the two connection terminals CN1 and CN2 (e.g., CN2) is connected to the other end of the first capacitor 104. Also, as shown in Figure 10, the switch 105 may further include other configurations such as a power supply terminal VD (used to be externally connected to a DC power supply VDD) and a plurality of ground terminals GND (used for electrical grounding), and a resistor R may be provided between the control terminal CTL and the ground terminal GND so that the control terminal CTL maintains an appropriate control voltage difference to control the switching state between the two connection terminals CN1 and CN2 to ON or OFF.

[0033] Referring again to Figure 9, the vehicle charging device 9A may be connected to the cloud computing platform 9D via the network 9C. For example, the charging connector plug provided by the vehicle charging device 9A can be inserted into the inlet of the electric vehicle 9B, and when the vehicle charging device 9A and the electric vehicle 9B form a coupler state, the vehicle charging device 9A can not only collect signal strength information as a basis for determining whether or not it is necessary to adjust the impedance of the communication line, but can also collect relevant vehicle information (e.g., manufacturer and model number). The information collected by the vehicle charging device 9A is aggregated and sent to the cloud computing platform 9D via the network 9C for big data analysis, which is advantageous in finding impedance matching methods that different vehicles apply when charging communication. Subsequently, for similar vehicles, the vehicle charging device 9A can adjust the impedance matching state of the communication line by referring to the recommended impedance matching method (e.g., provided by the cloud computing platform), smoothly complete the charging communication operation, and then perform the subsequent charging mode.

[0034] On the other hand, as shown in Figure 11, an embodiment of the present invention provides a vehicle charging method example 110, which is applicable to the vehicle charging device described above (for example, the vehicle charging device 9A shown in Figure 9 may be configured as a charging station for an electric vehicle), and includes steps 111 to 115. Examples are given below, but are not limited to these.

[0035] As shown in Figure 11, in step 111, the electric vehicle is connected to a charging station. For example, the vehicle charging device 9A shown in Figure 9 detects the connection between the two communication lines 93 connected to the vehicle charging device 9A and the electric vehicle 9B, and then proceeds to step 112.

[0036] As shown in Figure 11, in step 112, power line communication is performed, for example, the vehicle charging device 9A and the electric vehicle 9B shown in Figure 9 perform power line communication (PLC), the vehicle charging device 9A collects the signal strength of multiple signal channels of the electric vehicle 9B, and then proceeds to step 113.

[0037] As shown in Figure 11, in step 113, the impedance matching of the communication lines is adjusted. For example, the vehicle charging device 9A shown in Figure 9 monitors the communication characteristics of the two communication lines 93 according to the signal strength of multiple signal channels, so that the signal strength of the two communication lines 93 meets the strength requirement. For example, the vehicle charging device 9A shown in Figure 9 calculates the average value of the signal strength according to the signal strength of multiple signal channels. For example, the average value of the signal strength is equal to the quotient between the sum of the multiple signal strengths and the number of signal strengths. Based on the average value of the signal strength and the signal strength threshold (for example, -31 dB, but not limited to this), the vehicle charging device 9A confirms that the signal strength of the two communication lines 93 meets the strength requirement. For example, the controller of the vehicle charging device 9A determines whether the average value of the signal strength is lower than the signal strength threshold. If it determines that it is lower, the controller of the vehicle charging device 9A adjusts the impedance of the two communication lines 93 in steps. For example, the vehicle charging device 9A can increase the equivalent capacitance of the two communication lines 93 by a predetermined amount (for example, by increasing the number of capacitors connected in parallel) to bring the ends of the vehicle charging device 9A and the electric vehicle 9B closer to impedance matching and improve the average signal strength, and the above calculation and judgment steps are performed again. If it is determined that the signal strength is not low, the controller of the vehicle charging device 9A confirms that the signal strength of the two communication lines 93 meets the strength requirement, and then steps 114 are performed.

[0038] As shown in Figure 11, in step 114, communication is completed and the vehicle enters charging mode. For example, as shown in Figure 9, in response to the signal strength of the two communication lines 93 meeting the strength requirement, the vehicle charging device 9A enters charging mode for the electric vehicle 9B. For example, the vehicle charging device 9A can also collect characteristic information of the electric vehicle 9B (e.g., signal strength and impedance characteristics of the communication lines 93, vehicle type, etc.) before or during the charging process and transmit the characteristic information to the cloud computing platform 9D. The cloud computing platform 9D can generate a charging method for the vehicle charging device 9A based on the characteristic information, and the vehicle charging device 9A can charge the electric vehicle 9B based on the charging method. This makes it possible to quickly and appropriately provide a charging method using big data content and reduce the occurrence of charging abnormalities.

[0039] As shown in Figure 11, the vehicle charging method example 110 includes a step 115 to complete charging, for example, as shown in Figure 9, in the charging mode, for example, the electric vehicle 9B can feed back power level information to the vehicle charging device 9A, and the vehicle charging device 9A can complete the charging mode when it detects that the power level of the electric vehicle 9B's battery is above a power level threshold, for example, the vehicle charging device 9A can output charging completion information, for example, by displaying it on a screen, emitting a sound, or sending a message to inform the user that the electric vehicle 9B is in a charging completion state.

[0040] In summary, the vehicle charging device and vehicle charging method of the present invention are configured such that the second side of the transformer of the vehicle charging device is provided with two communication lines (having capacitors) to be connected to an electric vehicle, each of the impedance tuners of the vehicle charging device is connected in parallel to one of the communication lines, and the two impedance tuners are configured to adjust the reactance characteristics of the two communication lines, for example, each of the two impedance tuners includes at least one branch path (including a switch and a capacitor), and each of the at least one branch path is connected in parallel to the capacitor of the communication line. Therefore, depending on the signal strength of the communication line, the connection between an appropriate number of branch path capacitors and the capacitor of the communication line can be controlled in stages, and by adjusting the impedance of the communication line, the vehicle charging device and the electric vehicle can communicate with each other in a state that approaches impedance matching, and abnormalities such as the electric vehicle being unable to charge or charging being interrupted due to a high bit error rate in data exchange can be avoided.

[0041] Although the present invention is disclosed in preferred embodiments, various modifications and alterations can be made by those skilled in the art without departing from the spirit and scope of the invention, so the scope of protection of the present invention is deemed to be defined by the appended claims. [Explanation of Symbols]

[0042] 10, 20, 50, 90, 100 vehicle charging systems 11, 21, 51 Charging Stand 12, 22, 52, 9B, 10B Electric Vehicles 13, 211, 511 controllers Examples of PSD profile curves 30 and 40 91, 101, 212, 512 transformers 92, 102 Impedance Tuner Branch routes 921 and 1021 23, 53, 93, 103 communication lines 513 Bandpass filter 60a, 70a Equivalent Circuit Examples 60b, 70b Insertion Loss Curve Examples 80. Example of a signal intensity curve 94, 104 First capacitor 95, 105 switches 96, 106 Second capacitor 9A, 10A vehicle charging device 9C Network 9D Cloud Computing Platform 110 Examples of vehicle charging methods Steps 111, 112, 113, 114, and 115 SPI_TX+, SPI_TX-, SPI_RX+, SPI_RX-, TXOUT_P, TXOUT_N, RXIN_P, RXIN_N signal lines C1, C2, C3 curves CP control pilot line PE protective earth wire CTL control terminal CN1, CN2 connection terminals VD power supply terminal VDD DC power supply GND Grounding terminal R resistance M1 sampling point

Claims

1. A transformer having a first side and a second side, the second side of which is provided with two communication lines to be connected to an electric vehicle, A vehicle charging device comprising: two impedance tuners, each connected in parallel to one of the two communication lines and configured to adjust the reactance characteristics of the two communication lines.

2. The vehicle charging device according to claim 1, wherein each of the two communication lines has a first capacitor, each of the two impedance tuners includes at least one branch path, and each of the at least one branch path is connected in parallel to the first capacitor.

3. The vehicle charging device according to claim 2, wherein each of the at least one branch path includes a switch and a second capacitor, the switch and the second capacitor being connected in series.

4. The vehicle charging device according to claim 3, wherein the switch is configured such that the first capacitor and the second capacitor form a parallel circuit or an open circuit based on a control signal from the controller.

5. The vehicle charging device according to claim 3, wherein the switch is a high-frequency switching element.

6. The vehicle charging device according to claim 5, wherein the operating frequency range of the high-frequency switching element includes 150 kHz to 30 MHz.

7. The vehicle charging device according to claim 5, wherein the high-frequency switching element is a chip-type switch having a control terminal and two connection terminals, the second capacitor is connected between one of the two connection terminals and one end of the first capacitor, and the other of the two connection terminals is connected to the other end of the first capacitor.

8. The vehicle charging device according to claim 1, wherein the two communication lines include a control pilot line and a protective earth line.

9. The vehicle charging device according to claim 1, wherein the vehicle charging device is connected to a cloud computing platform via a network.

10. A vehicle charging method applied to a vehicle charging device, comprising: a transformer having a first side and a second side, the second side of which is provided with two communication lines to be connected to an electric vehicle; and two impedance tuners, each connected in parallel to one of the two communication lines and configured to adjust the reactance characteristics of the two communication lines, The steps include detecting the connection between the two communication lines connected to the vehicle charging device and the electric vehicle, The vehicle charging device and the electric vehicle communicate via power lines, and the vehicle charging device collects the signal strength of multiple signal channels of the electric vehicle. The vehicle charging device monitors the communication characteristics of the two communication lines based on the signal strength of the plurality of signal channels, and ensures that the signal strength of the two communication lines satisfies the strength requirements. A vehicle charging method comprising the step of: the vehicle charging device entering a charging mode for the electric vehicle in response that the signal strength of the two communication lines satisfies the strength requirement.

11. The vehicle charging device monitors the communication characteristics of the two communication lines based on the signal strength of the multiple signal channels, and the step of ensuring that the signal strength of the two communication lines satisfies the strength requirement is: The vehicle charging device calculates the average signal strength based on the signal strength of the multiple signal channels, The vehicle charging method according to claim 10, further comprising: the vehicle charging device confirming that the signal strength of the two communication lines meets the strength requirement based on the average value of the signal strength and the signal strength threshold.

12. The vehicle charging device confirms that the signal strength of the two communication lines meets the strength requirement based on the average value of the signal strength and the threshold value of the signal strength. The vehicle charging method according to claim 11, comprising: determining whether the average value of the signal strength is lower than a threshold value of the signal strength; if it is determined to be lower, increasing the equivalent capacitance value of the two communication lines by a predetermined amount, and repeating the calculation and determination; and if it is determined to be higher than the average value of the signal strength, the vehicle charging device confirming that the signal strength of the two communication lines meets the strength requirement.

13. The vehicle charging method according to claim 11, wherein the threshold value of the signal intensity is -31 dB.

14. The vehicle charging device is connected to a cloud computing platform via a network, and the vehicle charging method is: The vehicle charging device collects characteristic information of the electric vehicle and transmits the characteristic information to the cloud computing platform, The cloud computing platform includes the steps of generating a charging method for the vehicle charging device based on the characteristic information, The vehicle charging method according to claim 10, further comprising the step of charging the electric vehicle based on the charging method.

15. The vehicle charging method according to claim 10, wherein each of the two communication lines has a first capacitor, each of the two impedance tuners includes at least one branch path, and each of the at least one branch path is connected in parallel to the first capacitor.

16. The vehicle charging method according to claim 15, wherein each of the at least one branch path includes a switch and a second capacitor, and the switch and the second capacitor are connected in series.

17. The vehicle charging method according to claim 16, wherein the switch is configured such that the first capacitor and the second capacitor form a parallel circuit or an open circuit based on a control signal from the controller.

18. The vehicle charging method according to claim 16, wherein the switch is a high-frequency switching element.

19. The vehicle charging method according to claim 18, wherein the operating frequency range of the high-frequency switching element includes 150 kHz to 30 MHz.

20. The vehicle charging method according to claim 18, wherein the high-frequency switching element is a chip-type switch having a control terminal and two connection terminals, the second capacitor is connected between one of the two connection terminals and one end of the first capacitor, and the other of the two connection terminals is connected to the other end of the first capacitor.

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