Precise Position Alignment System and Alignment Method for Wireless Charging Coils of Electric Vehicles

Abstract

Precise position alignment system and alignment method for wireless charging coil of electric vehicle, which relates to the technical field of wireless charging technology for electric vehicles. It includes a processor and multiple eddy current sensors. The eddy current sensors include a resonant coil module and a preamplifier. The resonant coil modules are arranged at intervals and installed at the bottom of the power receiving coil module. The output ends of the eddy current sensors are respectively connected to the processor through a switching switch, and the control end of the switching switch is connected to the processor; when the power receiving coil module and the charging coil module are in an aligned state, the resonant coil modules respectively overlap with the upper and lower positions of the metal ring of the charging coil. The present invention can detect the alignment situation between the power receiving coil module and the charging coil module before wireless charging, which is convenient for alignment adjustment when the alignment situation is poor, thereby improving the wireless charging efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless charging for electric vehicles, and specifically to an accurate position alignment system and alignment method for a wireless charging coil of an electric vehicle. Background Art

[0002] The field of electric vehicles is booming. As an important part in the use of electric vehicles, the technology of electric vehicle charging piles affects the popularization and use of electric vehicles. And the wireless charging technology for electric vehicle charging piles is the future development direction, while the existing wired electric vehicle charging piles have many inconveniences.

[0003] The existing wireless charging system includes a power receiving coil module installed at the bottom of the vehicle and a charging coil module installed on the ground. During charging, if there is a difference in the positions of the power receiving coil module and the charging coil module, there will be a large loss in the power transmission efficiency, and there is no disclosed alignment detection measure in the existing technology. Summary of the Invention

[0004] One of the purposes of the present invention is to provide an accurate position alignment system for a wireless charging coil of an electric vehicle, which can effectively solve the technical problems in the background art.

[0005] The technical solution to achieve the above purpose is: an accurate position alignment system for a wireless charging coil of an electric vehicle, used for the alignment detection of a power receiving coil module installed at the bottom of the vehicle and a charging coil module installed on the ground. The power receiving coil module includes a power receiving coil and a first insulating housing encapsulated outside the power receiving coil. The charging coil module includes a charging coil and a second insulating housing encapsulated outside the charging coil. It is characterized in that: the alignment system includes a processor and a plurality of eddy current sensors. The eddy current sensors include a resonant coil module and a preamplifier. The resonant coil modules are arranged at intervals at the bottom of the power receiving coil module. The output ends of the eddy current sensors are respectively connected to the processor through a switching switch, and the control end of the switching switch is connected to the processor;

[0006] When the power receiving coil module and the charging coil module are in an aligned state, the resonant coil modules respectively overlap with the upper and lower positions of the metal ring of the charging coil.

[0007] Further, both the charging coil and the power receiving coil are spiral. The resonant coil modules are arranged in a spiral shape at the bottom of the power receiving coil module and have the same number of turns as the metal rings of the charging coil. When the power receiving coil module and the charging coil module are in an aligned state, each turn of the resonant coil modules respectively overlaps with the upper and lower positions of each metal ring of the charging coil.

[0008] Further, the resonant coil module includes a resonant coil and a third insulating housing encapsulated outside the resonant coil.

[0009] Further, the resonant coil is a PCB coil and is in a planar circular spiral shape, and the maximum outer diameter of the resonant coil is 10-20 mm.

[0010] Further, the eddy current sensor includes a power supply module V1, resistors R1, R2, R3, R4, R5, R6, R7, R8, R21, R22, R23, a resonant coil L1, a variable resistor R20, capacitors C1, C2, C4, C5, C10, C11, a triode Q4, a diode D1, and an operational amplifier U2A. The negative terminal of the power supply module V1 is grounded, and the positive terminal is connected to one end of the resistor R1. The other end of the resistor R1 is respectively connected to one end of the capacitor C4, the B pole of the triode Q4, and one end of the resistor R23. The E pole of the triode Q4 is connected to the ground after being connected in series with the resistor R8. The other ends of the capacitor C4 and the resistor R23 are connected in parallel and then connected to one ends of the capacitors C2 and C11. The other end of the capacitor C2 is connected to one end of the capacitor C1. The other end of the capacitor C11 is connected to one end of the resonant coil. The other end of the resonant coil and the other end of the capacitor C1 are connected in parallel and then respectively connected to the C pole of the triode Q4 and one end of the resistor R22. The other end of the resistor R22 is connected to the positive pole of the power supply module V1;

[0011] One ends of the resistor R21 and the capacitor C5 are connected in parallel with each other and connected to the C pole of the triode Q4. The other ends of the resistor R21 and the capacitor C5 are connected in parallel with each other and then connected to the positive pole of the diode D1. The negative pole of the diode D1 is respectively connected to one end of the capacitor C6 and the resistor R7. The other end of the capacitor C6 is grounded. The other end of the resistor R7 is respectively connected to one end of the resistor R6 and the non-inverting input terminal of the operational amplifier U2A. The other end of the resistor R6 is grounded. The power supply terminal of the operational amplifier U2A is connected to the power supply module V1. The inverting input terminal of the operational amplifier U2A is respectively connected to one ends of the resistor R3 and the capacitor C10. The other end of the resistor R3 is connected to the ground after being connected in series with the variable resistor R20. The other end of the capacitor C10 is connected to the output terminal of the operational amplifier U2A after being connected in series with the resistor R5. The resistor R4 is connected in parallel across the capacitor C10. The output terminal of the operational amplifier U2A is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the processor after being connected in series with a switching switch.

[0012] Another object of the present invention is to provide an alignment method for an accurate position alignment system of an electric vehicle wireless charging coil, which is characterized in that it includes the following steps:

[0013] 1) The power receiving coil module of the charging vehicle is initially positioned above the charging coil module, and the distance between the resonant coil module and the charging coil module is within the sensing distance range of the eddy current sensor;

[0014] 2) The MCU processor separately controls the switching switches at the output ends of the eddy current sensors to be connected one by one, and then obtains the voltage value V at the output end of each eddy current sensor. Let the number of eddy current sensors be N, where N is an integer. Let the voltage values output by the N eddy current sensors be V1, V2, V3... VN n ;

[0015] 3) Calculate the absolute value of the difference between the output voltage value of each eddy current sensor and the output voltage value of any other eddy current sensor, and then determine whether the absolute value of each difference is within the allowable error range. If the absolute values of all differences are within the allowable error range, the charging coil module and the power receiving coil module are in an aligned state. If the absolute value of any one or more differences exceeds the allowable error range, the charging coil module and the power receiving coil module are in an unaligned state.

[0016] Advantages of the present invention:

[0017] The present invention can detect the alignment of the power receiving coil module and the charging coil module before wireless charging, facilitating alignment adjustment when the alignment is poor, thereby improving the wireless charging efficiency. Description of the Drawings

[0018] Figure 1 is a principle block diagram of the present invention;

[0019] Figure 2 is a structural diagram of a wireless charging coil configured with eddy current sensors;

[0020] Figure 3 is a schematic diagram of the positional relationship between the resonant coil module and the charging coil in the aligned state;

[0021] Figure 4 is a schematic diagram of the structure of the resonant coil;

[0022] Figure 5 is a circuit diagram of the eddy current sensor. Detailed Embodiments

[0023] As Figures 1-5 shown, the present invention discloses an accurate position alignment system for a wireless charging coil of an electric vehicle, which is used for alignment detection of a power receiving coil module 1 installed at the bottom of the vehicle and a charging coil module 2 installed on the ground. The power receiving coil module 1 includes a power receiving coil and a first insulating housing (not shown in the figure) encapsulated outside the power receiving coil, and the charging coil module 2 includes a charging coil 2.1 and a second insulating housing encapsulated outside the charging coil.

[0024] As a further description of this embodiment, the charging coil 2.1 and the power receiving coil are square planar spirals or circular planar spirals commonly used by those skilled in the art.

[0025] The alignment system includes an MCU processor 3 and multiple identical eddy current sensors 4. The eddy current sensor 4 includes a resonant coil module 5 and a preamplifier 6. The resonant coil module 5 is arranged in a spiral shape at the bottom of the power receiving coil module 1, and the number of spiral turns is the same as the number of metal turns of the charging coil 2.1. The output ends of the eddy current sensors 4 are respectively connected to the MCU processor 3 through a switching switch K1, and the control end of the switching switch K1 is connected to the MCU processor 3. The switching switch K1 can be, but is not limited to, a relay.

[0026] When the power receiving coil module 1 and the charging coil module 2 are in an aligned state, each turn of the resonant coil module 5 overlaps with the upper and lower positions of the corresponding metal turn of the charging coil 2.1. The resonant coil module 5 includes a resonant coil L1 and a third insulating housing 5.2 encapsulated outside the resonant coil L1. The resonant coil L1 is a PCB coil and is in a planar circular spiral shape. The maximum outer diameter of the resonant coil L1 is a, and a = 10 - 20 mm.

[0027] As the eddy current sensor 4 in this embodiment, an existing publicly available product can be used, or the following circuit structure can be adopted. Specifically:

[0028] The eddy current sensor 4 includes a power supply module V1, resistors R1, R2, R3, R4, R5, R6, R7, R8, R21, R22, R23, a resonant coil L1, a variable resistor R20, capacitors C1, C2, C4, C5, C10, C11, a triode Q4, a diode D1, and an operational amplifier U2A. The negative terminal of the power supply module V1 is grounded, and the positive terminal is connected to one end of the resistor R1. The other end of the resistor R1 is respectively connected to one end of the capacitor C4, the B - pole of the triode Q4, and one end of the resistor R23. The E - pole of the triode Q4 is connected to the ground after being connected in series with the resistor R8. The other ends of the capacitor C4 and the resistor R23 are connected in parallel and then connected to one ends of the capacitors C2 and C11. The other end of the capacitor C2 is connected to one end of the capacitor C1. The other end of the capacitor C11 is connected to one end of the resonant coil L1. The other end of the resonant coil L1 is connected in parallel with the other end of the capacitor C1 and then respectively connected to the C - pole of the triode Q4 and one end of the resistor R22. The other end of the resistor R22 is connected to the positive pole of the power supply module V1;

[0029] One end of the resistor R21 and the capacitor C5 are connected in parallel with each other and connected to the C pole of the triode Q4. The other ends of the resistor R21 and the capacitor C5 are connected in parallel with each other and then connected to the positive pole of the diode D1. The negative pole of the diode D1 is respectively connected to one end of the capacitor C6 and the resistor R7. The other end of the capacitor C6 is grounded. The other end of the resistor R7 is respectively connected to one end of the resistor R6 and the non-inverting input terminal of the operational amplifier U2A. The other end of the resistor R6 is grounded. The power supply terminal of the operational amplifier U2A is connected to the power supply module V1. The inverting input terminal of the operational amplifier U2A is respectively connected to one end of the resistor R3 and the capacitor C10. The other end of the resistor R3 is connected to the ground after being connected in series with the adjustable resistor R20. The other end of the capacitor C10 is connected to the output terminal of the operational amplifier U2A after being connected in series with the resistor R5. The resistor R4 is connected in parallel across the two ends of the capacitor C10. The output terminal of the operational amplifier U2A is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the MCU processor 3 after being connected in series with the switching switch K1.

[0030] As a further description of this embodiment, the power supply module V1 is powered by an automotive power supply.

[0031] The eddy current sensor 4 realizes alignment detection by utilizing the characteristic that different voltage values are generated due to the change in the distance between the resonant coil and the charging coil. The specific principle is as follows:

[0032] When the eddy current sensor 4 works, the output voltage of the power supply module V1 generates an oscillating voltage signal with a certain amplitude through the oscillating circuit composed of the resonant coil L1, capacitors C1, C2, and C11. The generated oscillating voltage signal adjusts the static operating point of the voltage signal by the DC bias resistors R1 and R22, and then compensates the amplitude of the oscillating voltage signal through the compensation positive feedback circuit composed of the resistor R23 and the capacitor C4. After that, the AC detection circuit composed of the resistor R21, capacitor C5, diode D1, and capacitor C6 rectifies and filters the voltage signal, and then divides the voltage through the resistors R6 and R7 and inputs it to the operational amplifier U2A. Finally, it is delivered to the MCU processor 3 through the current-limiting resistor R2. Among them, the adjustable resistor R20 is an adjustable gain operational amplifier resistor, and the resistors R3, R4, and R5 constitute a gain amplification multiple circuit.

[0033] When the present invention works, a high-frequency electromagnetic field is generated when the resonant coil L1 works. When the charging coil 2.1 approaches this high-frequency electromagnetic field, eddy currents will be generated in the charging coil 2.1. The eddy currents absorb the energy of the high-frequency electromagnetic field and the oscillating circuit composed of the coil L1, capacitors C1, C2, and C11. The energy of the eddy currents generated by the charging coil 2.1 is absorbed and attenuated. The voltage amplitude of the eddy current sensor 4 changes with the size of the eddy current. When the resonant coil L1 is aligned to the target position, at this time, the eddy current losses of the resonant coil L1 are the same, and the voltage amplitudes output by the eddy current sensor 4 are the same or the error values are within the allowable range.

[0034] The specific alignment detection steps are as follows:

[0035] 1) The power receiving coil module 1 of the charging vehicle is initially positioned above the charging coil module 2, and the distance between the resonant coil module 5 and the charging coil module 2 is within the sensing distance range of the eddy current sensor 4;

[0036] 2) The MCU processor 3 controls the switching switch K1 at the output end of the eddy current sensor 4 to be turned on one by one, and then obtains the voltage value V at the output end of each eddy current sensor 4. Let the number of eddy current sensors 4 be N, where N is an integer. Let the voltage values output by the N eddy current sensors 4 be V1, V2, V3... V n ;

[0037] 3) Calculate the absolute value of the difference between the output voltage value of each eddy current sensor 4 and the output voltage value of any other eddy current sensor 4, and then determine whether the absolute value of each difference is within the allowable error range. If the absolute values of all differences are within the allowable error range, the charging coil module 2 and the power receiving coil module 1 are in an aligned state. If the absolute value of any one or more differences exceeds the allowable error range, the charging coil module 2 and the power receiving coil module 1 are in an unaligned state.

[0038] The allowable error range of the absolute value of the difference in the output voltage between the eddy current sensors 4 is obtained before the product leaves the factory by adjusting the charging coil module 2 and the power receiving coil module 1 configured with the alignment system disclosed in this embodiment to a set distance and in an aligned state, and then the MCU obtains the absolute value of the output voltage difference of the eddy current circuit and calculates the average value through multiple verifications.

[0039] Further, when calculating the absolute value of the difference in the output voltage between the eddy current sensors 4, the output voltage of one of the eddy current sensors 4 can be subtracted from the output voltages of other eddy current sensors 4, such as |V1 - V2|, |V1 - V3|, |V1 - V4|... |V1 - V n |; It can also be obtained by subtracting the output voltages of adjacent eddy current sensors 4, such as |V1 - V2|, |V2 - V3|, |V3 - V4|... |V n-1 - V n |.

Claims

1. An accurate position alignment system for a wireless charging coil of an electric vehicle, used for alignment detection of a power receiving coil module installed at the bottom of the vehicle and a charging coil module installed on the ground. The power receiving coil module includes a power receiving coil and a first insulating housing encapsulated outside the power receiving coil. The charging coil module includes a charging coil and a second insulating housing encapsulated outside the charging coil, characterized in that: The alignment system includes an MCU processor and multiple eddy current sensors. Each eddy current sensor includes a resonant coil module and a preamplifier. The resonant coil modules are arranged at intervals at the bottom of the power receiving coil module. The output ends of the eddy current sensors are respectively connected to the processor through a switching switch, and the control end of the switching switch is connected to the processor; When the power receiving coil module and the charging coil module are in an aligned state, the resonant coil modules respectively overlap the upper and lower positions of the metal rings of the charging coil; The resonant coil module includes a resonant coil and a third insulating housing encapsulated outside the resonant coil; The alignment method of the alignment system includes the following steps: 1) The power receiving coil module of the charging vehicle is initially positioned above the charging coil module, and the distance between the resonant coil module and the charging coil module is within the induction distance range of the eddy current sensor; 2) The MCU processor separately controls the switching switches at the output ends of the eddy current sensors to be turned on one by one, and then obtains the voltage value V at the output end of each eddy current sensor. Let the number of eddy current sensors be N, where N is an integer. Let the voltage values output by the N eddy current sensors be V1, V2, V3... V n ; 3) Calculate the absolute value of the difference between the output voltage value of each eddy current sensor and the output voltage value of any other eddy current sensor, and then determine whether the absolute value of each difference is within the allowable error range. If the absolute values of all differences are within the allowable error range, the charging coil module and the power receiving coil module are in an aligned state. If the absolute value of any one or more differences exceeds the allowable error range, the charging coil module and the power receiving coil module are in an unaligned state.

2. The precise position alignment system for the wireless charging coil of an electric vehicle according to claim 1, characterized in that: Both the charging coil and the power receiving coil are spiral. The resonant coil modules are arranged in a spiral at the bottom of the power receiving coil module and have the same number of turns as the metal rings of the charging coil. When the power receiving coil module and the charging coil module are in an aligned state, each turn of the resonant coil module respectively overlaps the upper and lower positions of each metal ring of the charging coil.

3. The precise position alignment system for the wireless charging coil of an electric vehicle according to claim 1, characterized in that: The resonant coil is a PCB coil and is in a planar circular spiral shape, and the maximum outer diameter of the resonant coil is 10 - 20 mm.

4. The precise position alignment system for the wireless charging coil of an electric vehicle according to claim 1, characterized in that: The eddy current sensor includes a power supply module V1, resistors R1, R2, R3, R4, R5, R6, R7, R8, R21, R22, R23, a resonant coil L1, a variable resistor R20, capacitors C1, C2, C4, C5, C10, C11, a triode Q4, a diode D1, and an operational amplifier U2A. The negative terminal of the power supply module V1 is grounded, and the positive terminal is connected to one end of the resistor R1. The other end of the resistor R1 is respectively connected to one end of the capacitor C4, the B pole of the triode Q4, and one end of the resistor R23. The E pole of the triode Q4 is connected to the ground through the resistor R8. The other ends of the capacitor C4 and the resistor R23 are connected in parallel and then connected to one ends of the capacitors C2 and C11. The other end of the capacitor C2 is connected to one end of the capacitor C1. The other end of the capacitor C11 is connected to one end of the resonant coil L1. The other end of the resonant coil L1 is connected in parallel with the other end of the capacitor C1 and then respectively connected to the C pole of the triode Q4 and one end of the resistor R22. The other end of the resistor R22 is connected to the positive pole of the power supply module V1; One end of the resistor R21 and the capacitor C5 are connected in parallel with each other and connected to the C pole of the triode Q4. The other ends of the resistor R21 and the capacitor C5 are connected in parallel with each other and then connected to the positive pole of the diode D1. The negative pole of the diode D1 is respectively connected to one end of the capacitor C6 and the resistor R7. The other end of the capacitor C6 is grounded. The other end of the resistor R7 is respectively connected to one end of the resistor R6 and the non-inverting input terminal of the operational amplifier U2A. The other end of the resistor R6 is grounded. The power supply terminal of the operational amplifier U2A is connected to the power supply module V1. The inverting input terminal of the operational amplifier U2A is respectively connected to one end of the resistor R3 and the capacitor C10. The other end of the resistor R3 is connected to the ground after being connected in series with the adjustable resistor R20. The other end of the capacitor C10 is connected to the output terminal of the operational amplifier U2A after being connected in series with the resistor R5. The resistor R4 is connected in parallel across the two ends of the capacitor C10. The output terminal of the operational amplifier U2A is connected to one end of the resistor R2. The other end of the resistor R2 is connected to the processor after being connected in series with a switching switch.

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