CN110293860B - Wireless charging coil guiding and aligning device and aligning method for electric automobile - Google Patents
Wireless charging coil guiding and aligning device and aligning method for electric automobile Download PDFInfo
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
- B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
- B60L53/12—Inductive energy transfer
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
- B60L53/60—Monitoring or controlling charging stations
- B60L53/66—Data transfer between charging stations and vehicles
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60W—CONJOINT CONTROL OF VEHICLE SUB-UNITS OF DIFFERENT TYPE OR DIFFERENT FUNCTION; CONTROL SYSTEMS SPECIALLY ADAPTED FOR HYBRID VEHICLES; ROAD VEHICLE DRIVE CONTROL SYSTEMS FOR PURPOSES NOT RELATED TO THE CONTROL OF A PARTICULAR SUB-UNIT
- B60W30/00—Purposes of road vehicle drive control systems not related to the control of a particular sub-unit, e.g. of systems using conjoint control of vehicle sub-units
- B60W30/06—Automatic manoeuvring for parking
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/70—Energy storage systems for electromobility, e.g. batteries
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T10/00—Road transport of goods or passengers
- Y02T10/60—Other road transportation technologies with climate change mitigation effect
- Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/10—Technologies relating to charging of electric vehicles
- Y02T90/12—Electric charging stations
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/10—Technologies relating to charging of electric vehicles
- Y02T90/14—Plug-in electric vehicles
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02T90/10—Technologies relating to charging of electric vehicles
- Y02T90/16—Information or communication technologies improving the operation of electric vehicles
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- Engineering & Computer Science (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Power Engineering (AREA)
- Automation & Control Theory (AREA)
- Charge And Discharge Circuits For Batteries Or The Like (AREA)
- Current-Collector Devices For Electrically Propelled Vehicles (AREA)
Abstract
The invention discloses an electric vehicle wireless charging coil guiding and aligning device and an aligning method, comprising the following steps: the system comprises ground emission equipment, vehicle-mounted receiving equipment, an image positioning system, a magnetic field excitation system and a magnetic resistance sensor group; the accurate position relation between the transmitting coil and the receiving coil can be obtained when the vehicle approaches the parking space or just enters the parking space through the image processing of the looking-around camera, and the travel path can be planned to guide the driver or the parking system to finish coil alignment, so that the technical problem that the alignment operation of the electric vehicle is easy to fail because the electric vehicle is required to approach the detection magnetic field excitation source to obtain the guide data in the related technology is solved; on the other hand, the magnetic resistance sensor has high sensitivity and detection precision, high-precision coordinate analysis can be provided in the action distance, and the accuracy and the reliability of coil alignment are improved through final alignment, checking and verification of the coil of the magnetic resistance sensor.
Description
Technical Field
The invention relates to the technical field of wireless charging of electric automobiles, in particular to a guiding and aligning device and a guiding and aligning method for wireless charging coils of electric automobiles.
Background
When the electric automobile is charged wirelessly, the receiving coil and the transmitting coil are required to be aligned, so that the offset of the two coils is ensured to be within the allowable range of the design value, and the optimal charging effect can be achieved; in order to facilitate a driver or a parking system to park a vehicle within an allowable charging range, the relative position of a receiving coil and a transmitting coil can be detected when an electric vehicle carrying the receiving coil is separated from the transmitting coil by a certain distance, and the driver or the parking system is guided to finish the alignment of the receiving coil and the transmitting coil;
the existing wireless charging technology generally adopts the steps that a detection sensor or an auxiliary detection coil is arranged on a receiving coil or a transmitting coil, an excitation detection magnetic field is generated through the transmitting coil or the receiving coil, and the sensor or the auxiliary detection coil senses the detection magnetic field to obtain the relative position between the receiving coil or the transmitting coil; for example, patent publication number CN 207442545U, the invention name is: patent of an alignment guide device and an induction charging system capable of alignment guide, discloses a technology in which at least one alignment coil is mounted on a receiving coil, a magnetic field is generated by energizing a transmitting coil, a direction signal is generated according to an induction voltage generated in the alignment coil, and the direction signal is used for guiding and alignment detection of the coil;
The technology of the patent has great design deficiency:
the first and the above patent technologies adopt the structure mode of the auxiliary detection coil, greatly increase the structure complexity of the transmitting coil or the receiving coil, can generate superimposed electromagnetic influence with the power transmitting coil and the receiving coil, and the detection precision is also easy to be interfered;
secondly, because the magnetic field signal generated by the closed coil such as the transmitting coil has fast attenuation along with the increase of the distance (inversely proportional to the third power of the distance), and is constrained by the safety control limit value of the electromagnetic environment by the national standard, the transmitted magnetic field intensity when the coil of the wireless charging of the electric automobile is guided and aligned is very small and is also easily influenced by magnetic substances or surrounding environments in the field, such as interference of metal objects, materials or other parking vehicles, etc., the detected working distance in the mode is obvious only near a magnetic field generating source, and when reliable position deviation data are obtained, the driver or parking system does not have sufficient operation space and reaction time to adjust the running route of the vehicle, and the coil alignment action which cannot be completed correctly can not be achieved, so that the use experience of the wireless charging of the electric automobile is greatly reduced.
Disclosure of Invention
In order to solve the technical problems, the invention provides the wireless charging coil guiding and aligning device and the aligning method for the electric automobile, when the electric automobile approaches a parking space or just enters the parking space, a panoramic overlooking picture around the automobile body can be shot through a panoramic camera, the parking space is reconstructed by an image positioning system to establish a coordinate system based on image pixels, the image pixel coordinates are converted into actual space coordinates according to the mark line size of the parking space, the relative positions of a transmitting coil and a receiving coil are analyzed, a parking path is planned, a driver or a parking system is guided to align the coils, then a magnetic field emitted by the transmitting coil is induced by a high-precision magnetic resistance sensor group, the final aligning process of the coils is obtained, the final aligning process of the coils is guided and confirmed, the aligning and verifying function is provided, the precision difference problem caused by manual operation is greatly reduced by intelligent aligning design, and the coil aligning effect is greatly enhanced.
The utility model provides an electric automobile wireless charging coil guide alignment device and alignment method, wherein:
the wireless charging coil of electric automobile guides alignment device includes: the system comprises ground emission equipment, vehicle-mounted receiving equipment, an image positioning system, a magnetic field excitation system and a magnetic resistance sensor group;
Further, the ground emission equipment is arranged in the parking space and is electrically connected with a power supply grid; the vehicle-mounted receiving equipment is arranged at the bottom of the electric automobile and is electrically connected with the vehicle-mounted power battery;
as an illustration, the ground emission device includes: the ground communication control unit, the transmitting end power converter, the transmitting end resonant network and the transmitting coil; a transmitting coil winding for exciting a magnetic field is arranged in the transmitting coil;
as an example, the in-vehicle receiving apparatus includes: the system comprises a vehicle-mounted communication control unit, a receiving end resonant network, a receiving end power converter and a receiving coil; a receiving coil winding for receiving a magnetic field is arranged in the receiving coil;
as an illustration, the vehicle-mounted communication control unit adopts a structure that the power battery is connected in series with a direct current converter to supply power;
as a principle explanation, in the wireless charging link of an electric automobile, when a receiving coil of the electric automobile is aligned with a ground transmitting coil, power frequency alternating current conveyed by a power supply grid is converted into high-frequency alternating current through a transmitting power converter, the high-frequency alternating current is applied to the transmitting coil and forms a high-frequency alternating magnetic field in the upper space of the transmitting coil, at the moment, the vehicle-mounted receiving coil senses the alternating magnetic field to generate alternating current, and then the alternating current is converted into direct current through a receiving end power converter and is input into a power battery to charge the power battery; in the whole charging process, the vehicle-mounted equipment and the ground equipment interact information through wireless communication interfaces of the vehicle-mounted communication control unit and the ground communication control unit, and respectively control and adjust the electric energy conversion of the receiving end power converter and the transmitting end power converter through the vehicle-mounted communication control unit and the ground communication control unit;
Further, the image positioning system is used for constructing a coordinate system of image pixels and guiding the electric automobile to align with the transmitting coil;
as an illustration, the image localization system comprises: a looking-around camera and an image processing unit; wherein, the looking around camera includes: the cameras are arranged around the vehicle body and are respectively used for collecting images in the front, rear, left and right directions of the vehicle;
further, after the surrounding view image of the vehicle body is obtained, a plurality of groups of cameras transmit the acquired images to an image processing unit, and after image processing, distortion correction and image stitching processing, a panoramic overlooking picture of the surrounding environment of the vehicle is obtained;
as an illustration, the image positioning system is powered by the power battery, and a dc converter can be connected in series between the power battery and the image positioning system to match the power supply voltage of the image positioning system;
as a preferable example, the number of the plurality of groups of cameras installed around the vehicle body is four groups or more;
as a preferred illustration, the camera employs a wide angle lens;
as an illustration of an application, the wide angle lens is a 180 ° fisheye lens;
Further, the magnetic field excitation system is arranged on the back surface of the transmitting coil and is used for exciting and transmitting an electromagnetic field for guiding alignment to the space above the transmitting coil;
as an illustration, the magnetic field excitation system comprises: a signal generator, an amplifying transmitting circuit and a transmitting antenna; when the electromagnetic field is generated by excitation, a signal generator generates a sinusoidal signal, the sinusoidal signal is sent into the amplifying transmitting circuit for power amplification, the amplified sinusoidal signal drives the transmitting antenna, and the generation value of the electromagnetic field strength accords with the electromagnetic field strength value allowed by national standard when the public area is charged in a wireless manner during design;
as an illustration, the power supply of the magnetic field excitation system is connected to a power supply grid, and is powered by the power supply grid;
as an application illustration, the transmitting antenna directly adopts the transmitting coil winding of the transmitting coil to act as, and the frequency of the electromagnetic field excited and emitted is in the range of 30 KHz-300 KHz;
further, the magnetic resistance sensor groups are arranged on four corners of the receiving coil and are used for detecting magnetic induction intensity of electromagnetic fields emitted by the magnetic field excitation system and distributed at each point of a parking space area;
As an example, the set of magnetoresistive sensors includes: 12 magneto-resistive sensors mounted at four corners of the receiving coil, 3 for each corner;
as an illustration, each of the corners is provided with a magneto-resistive sensor along three axes X ', Y ' and Z ';
as an illustration, four magneto-resistive sensors mounted in the X 'axis direction, whose magnetic field sensitivity direction is-X' direction, are opposite to the traveling direction of the car when the coil is directed and aligned;
as an illustration, four magneto-resistive sensors installed in the Y' axis direction, whose magnetic field sensitivity direction is perpendicular to the traveling direction of the car when the coil is directed and aligned, and magneto-resistive sensors located at both sides of the receiving coil, whose magnetic field sensitivity directions are opposite to each other and are respectively directed toward the car body side of the car; as shown in fig. 3, the magnetic field sensitivity direction of the magneto-resistive sensor located in the Y 'axis direction mounted on the left side of the receiving coil is-Y' direction, and the magnetic field sensitivity direction of the magneto-resistive sensor located in the Y 'axis direction mounted on the right side of the receiving coil is +y' direction;
as an illustration, four magneto-resistive sensors mounted in the Z' axis direction are mounted upright, i.e. perpendicular to the receiving coil; the magnetic field sensitivity direction of the four magnetic resistance sensors is +Z' direction, is in the same direction with the axial direction of the receiving coil winding and points to the vehicle bottom;
As an illustration, the magneto-resistive sensor employs one or a combination of anisotropic magneto-resistive elements, giant magneto-resistive elements, or tunnel magneto-resistive elements;
as an application illustration, the tunnel magneto-resistance element has the advantages of high precision, high reliability, high response speed, high sensitivity, low cost and the like, the magneto-resistance sensor adopting the tunnel magneto-resistance element can cause the resistance change of the internal magneto-resistance element under the action of a magnetic field, when the internal circuit of the magneto-resistance sensor adopts a wheatstone bridge structure, the change of the magneto-resistance intensity can cause the change of the output voltage of the internal circuit of the magneto-resistance sensor, when the internal circuit of the magneto-resistance sensor is provided with circuits such as signal amplification, filtering and the like, the output voltage of the magneto-resistance sensor is in a direct proportion relation with the magneto-resistance intensity of an external magnetic field in a linear range, and the voltage signal output by the magneto-resistance sensor is connected to the analog input end of the vehicle-mounted communication control unit for conversion, processing and analysis, so that the magneto-resistance information of corresponding position and direction can be obtained;
as an application illustration, the magnetic resistance sensor group can also be arranged on the outer side of the receiving coil, the sensor group and the receiving coil are required to be kept in the same plane during installation, the number and the distribution of the sensors are the same as those of the sensors when the sensors are arranged at four corners of the receiving coil, three magnetic resistance sensors in the three axial directions of X ' Y ' Z ' have a fixed position relation with one corner of the receiving coil, and the coordinates obtained by the magnetic resistance sensors can be conveniently converted into the position coordinates of the four corners of the receiving coil;
The wireless charging coil guiding and aligning method for the electric automobile comprises the following steps:
when an automobile to be charged approaches or enters a parking space capable of being charged in a wireless mode, the electric automobile opens a vehicle-mounted communication control unit, and communication with a ground communication control unit is established;
step two, the ground communication control unit sends a confirmation instruction to the vehicle-mounted communication control unit, starts guiding alignment operation, and sends parking space information, a magnetic field positioning calibration value and a pairing check code value to the vehicle-mounted communication control unit;
as an example, the parking space information includes: the length and width of the parking space, the width of the marking line and the size data of the installation position of the transmitting coil;
as an illustration, the magnetic field positioning calibration values include: corresponding magnetic field induction B within allowable deviation range z1 Corresponding to the magnetic induction B of the magnetic field when the coils are fully aligned z0 ；
Step three, when the electric automobile is guided to be aligned, the ground communication control unit controls the magnetic field excitation system to generate an electromagnetic field; the electromagnetic field is transmitted in two periods, and the electromagnetic signal does not transmit in the first period; the second period is to emit electromagnetic field from the emitting coil to the upper space; in the first period, the magnetic induction intensity of the environment magnetic field is measured by the magnetic resistance sensor group; subtracting the environmental magnetic induction intensity of the first period from the magnetic induction intensity measured by the magnetic resistance sensor group in the second period to obtain the magnetic field magnetic induction intensity distributed at the position of the electromagnetic field emitted by the transmitting coil;
Step four, guiding the alignment operation of the electric automobile to adopt an image positioning mode, taking a panoramic overlook picture of the parking space by a panoramic camera of an image positioning system, converting the picture into a gray picture by an image processing unit through visual angle conversion, identifying the mark line of the parking space according to the color and geometric characteristics of the mark line of the parking space, reconstructing an outline image of the parking space through image processing and correction, and establishing an image coordinate system taking image pixels as units according to the resolution of the image processing unit (as shown in figure 3);
the position relation between the transmitting coil and the parking space is fixed, the installation position of the receiving coil on the electric automobile is also fixed, and the image pixel deviation values of four corners of the receiving coil and four corners of the transmitting coil on an X-Y plane can be determined according to the position of the looking-around camera and an image coordinate system established by the image positioning system; the image pixel coordinates of four corners of the receiving coil in the X-Y plane can be determined by taking the center (0, 0) of the transmitting coil as an origin; the geometric dimension of the parking space is known, and the actual dimension value corresponding to the image pixel can be obtained according to the geometric dimension of the parking space, including the dimension values such as the length, the width or the width of the mark line of the parking space, so that the actual dimension coordinates of four corners of the receiving coil on the X-Y plane can be determined;
As an illustration, in order for the image positioning system to better identify and reconstruct a parking space, other marker bits such as straight lines, geometric figures, grids and the like can be added in the parking space, and the marker bits are in fixed position relation with the parking space marker lines and the transmitting coils;
step five, the image processing unit sends the obtained four-angle coordinates of the receiving coil to the vehicle-mounted communication control unit, and the image positioning system continuously updates the four-angle coordinates of the receiving coil in the travelling process;
when the wireless charging guiding alignment operation is manually operated by a driver, the deviation between coils can be displayed through terminals such as a mobile phone, a vehicle-mounted center console and the like, and a parking path aligned by the coils is indicated according to the position deviation planning between the coils, so that driving instructions for adjusting the advancing direction such as the steering direction, the steering angle and the like are displayed for the driver;
when automatic parking or automatic driving is adopted, four-corner coordinates of the receiving coil are sent to a parking system, and the parking system plans automatic parking and realizes the path of coil alignment;
the electric automobile is operated by the manual operation or the automatic parking system, so that the X' axis of the receiving coil and the X axis of the transmitting coil are overlapped when the electric automobile runs, and the electric automobile is gradually close to the transmitting coil;
Step six, when the electric automobile approaches the position of the transmitting coil gradually, the intensity of an electromagnetic field signal sent by the magnetic resistance sensor group receiving magnetic field excitation system is increased gradually, and as the measurement of the looking-around camera is possibly delayed in processing speed and some calculation deviation, the external environment is possibly interfered, and when the magnetic field magnetic induction intensity sent by the magnetic field excitation system is enough to cover all the magnetic resistance sensors, the positioning and guiding operation of the electric automobile is switched into the guiding and aligning operation by adopting coordinate data generated by the magnetic resistance sensor group in real time;
step seven, the vehicle-mounted communication control unit sends the continuously collected magnetic induction intensity, namely 4*3 magnetic induction intensity values in total in the three-axis directions of four corners X ' Y ' Z ' of the receiving coil, voltage values generated by the change of the magnetic induction intensity, to an analog quantity conversion circuit of the vehicle-mounted communication control unit for processing, converting the voltage values into digital signals, obtaining magnetic field magnetic induction intensity in the three-axis directions of four corners of the receiving coil, and obtaining four three-axis coordinates of four corners of the receiving coil through the conversion of a distribution data model of the magnetic field magnetic induction intensity;
as an illustration, the magnetic field induction intensity distribution data model can adopt a magnetic dipole model, namely, a transmitting coil is idealized into a magnetic dipole, and the magnetic field induction intensity B of each point XYZ three-axis direction in a magnetic field coverage space can be obtained x 、B y and Bz When the center (0, 0) of the transmitting coil is set as the origin of the XYZ three-axis coordinates, the magnetic induction (B) of the magnetic field in the three-axis direction for a certain point (x, y, z) x ,B y ,B z ) The following formulas are respectively provided:
wherein ,B T for the fixed parameters related to the transmitting coil, the parameters such as the number of turns, the material, the diameter and the like of the coil are related to the non-requirement of the transmitting coilCalibrating in advance;
the three-axis coordinates (X, Y, z) of the measuring points can be obtained according to the model, so that the coordinates of the four corners of the receiving coil in the X-Y plane can be continuously obtained according to the magnetic induction intensity of the three-axis magnetic field measured at the four corners of the receiving coil;
the electric automobile is driven to the four corners of the receiving coil through manual operation of a driver or adjustment of the automobile by an automatic parking and driving system, the deviation of the X axis and the Y axis is reduced to be within the allowable deviation range between the coils when the wireless charging system is charged, and the electric automobile is aligned as accurately as possible;
step eight, in the final alignment stage, that is, when the projection of the receiving coil and the transmitting coil begin to overlap, the final alignment state can be judged or assisted by adopting a magnetic field positioning calibration value, that is, the magnetic field induction intensity value B corresponding to the magnetic resistance sensor calibrated in advance in the Z' axis direction within the allowable coil deviation range according to different transmitting coils z1 And magnetic field induction B corresponding to the magnetic resistance sensor in the Z' axis direction when the transmitting coil and the receiving coil are completely aligned z0 ；
When the magnetic induction intensity of the magnetic field received by the four magnetic resistance sensors at the four corners Z' axis of the receiving coil is not lower than the standard value B z1 When the transmitting coil and the receiving coil are aligned, the position deviation is considered to be within the allowable range of charging; when the magnetic induction intensity of the magnetic field received by the four-angle Z' -axis sensor of the receiving coil is equal or the deviation value is minimum, and the magnetic induction intensity of the received magnetic field is not lower than the standard value B z0 When the transmit coil and the receive coil are considered to be perfectly aligned;
and step nine, after the transmitting coil is aligned with the receiving coil, exciting and transmitting a verification electromagnetic field through the transmitting coil, when four magnetic resistance sensors in the four corners Z axis all receive electromagnetic signals exceeding a certain intensity amplitude, taking the electromagnetic signal with a long period as 1 and the electromagnetic signal with a short period as 0, if the binary code formed by 01 is consistent with the pairing verification code value transmitted through communication, the verification is successful, the verification process of the guiding alignment of the coil is completed, and a ground communication control unit transmits a signal to a vehicle-mounted communication control unit to confirm that the vehicle-mounted communication control unit has wireless charging conditions and starts wireless charging operation.
The beneficial effects are that:
with the rapid development of intelligent driving technology, vision systems such as a looking-around camera and the like are increasingly configured on the electric automobile, the accurate position relation between a transmitting coil and a receiving coil can be obtained when a vehicle approaches a parking space or just enters the parking space through image processing of the looking-around camera, and a travel path can be planned to guide a driver or a parking system to finish coil alignment, so that the technical problem that the alignment operation of the electric automobile is easy to fail because the electric automobile is required to approach a detection magnetic field excitation source to obtain guide data in the related technology is solved;
on the other hand, the magnetic resistance sensor has high sensitivity and detection precision, high-precision coordinate analysis can be provided within the action distance of the magnetic resistance sensor, and the accuracy and the reliability of coil alignment are improved through the final alignment, inspection and verification of the coil of the magnetic resistance sensor;
compared with the coil alignment operation of wireless charging in the prior art, the invention has higher alignment precision, safe and reliable operation and higher cost performance;
drawings
FIG. 1 is a schematic diagram of the whole structure of a wireless charging coil guiding and aligning device for an electric vehicle according to the present invention
FIG. 2 is a diagram showing the effect of installing a MR sensor group of the wireless charging coil guide alignment device for an electric vehicle according to the present invention
FIG. 3 is a schematic diagram showing the resolution of the image processing system of the wireless charging coil guide alignment device for an electric vehicle according to the present invention, establishing an image coordinate system in image pixels
FIG. 4 is a diagram of a ground reference coordinate system established by taking the center of a transmitting coil above the transmitting coil of the wireless charging coil guiding and aligning device for an electric vehicle as an origin
Detailed Description
Referring to fig. 1 to 4, an alignment device and an alignment method for guiding a wireless charging coil of an electric vehicle are shown, wherein:
the wireless charging coil of electric automobile guides alignment device includes: a ground emission device 101, a vehicle-mounted receiving device 102, an image positioning system 103, a magnetic field excitation system 104, and a magnetoresistive sensor group 105;
further, the ground emission device 101 is installed in the parking space and is electrically connected with the power supply grid 106; the vehicle-mounted receiving device 102 is arranged at the bottom of the electric automobile and is electrically connected with the vehicle-mounted power battery 107;
as an illustration, the ground emission device 101 includes: a ground communication control unit 108, a transmitting-side power converter 109, a transmitting-side resonant network 110, and a transmitting coil 111; a transmitting coil winding for exciting a magnetic field is provided inside the transmitting coil 111;
As an example, the in-vehicle receiving apparatus 102 includes: a vehicle-mounted communication control unit 112, a receiving-end resonant network 113, a receiving-end power converter 114, and a receiving coil 115; a receiving coil winding for receiving a magnetic field is provided in the receiving coil 115;
as an illustration, the vehicle-mounted communication control unit 112 adopts the structure that the power battery 107 is connected in series with the dc converter 120 to supply power;
as a principle explanation, in the wireless charging link of the electric automobile, when the receiving coil 115 of the electric automobile is aligned with the ground transmitting coil 111, the power frequency alternating current transmitted by the power supply grid 106 is converted into high frequency alternating current by the transmitting power converter 109, the high frequency alternating current is applied to the transmitting coil 111 and forms a high frequency alternating magnetic field in the upper space of the transmitting coil, at this time, the vehicle receiving coil 115 senses the alternating magnetic field to generate alternating current, and then the alternating current is converted into direct current by the receiving end power converter 114 and is input into the power battery 107 to charge the power battery 107; in the whole charging process, the vehicle-mounted equipment and the ground equipment exchange information through wireless communication interfaces of the vehicle-mounted communication control unit 112 and the ground communication control unit 108, and respectively control and adjust the electric energy conversion of the receiving end power converter 114 and the transmitting end power converter 109 through the vehicle-mounted communication control unit 112 and the ground communication control unit 108;
Further, the image positioning system 103 is configured to construct a coordinate system of image pixels, and guide the electric vehicle to align with the transmitting coil 111;
as an illustration, the image localization system 103 comprises: a looking-around camera 116 and an image processing unit 117; wherein the looking-around camera 116 comprises: the cameras are arranged around the vehicle body and are respectively used for collecting images in the front, rear, left and right directions of the vehicle;
further, after obtaining the looking-around image around the vehicle body, the plurality of groups of cameras transmit the collected images to the image processing unit 117, and after performing image processing, distortion correction and image stitching processing, a panoramic overlook image of the surrounding environment of the vehicle is obtained;
as an illustration, the image positioning system 103 is powered by the vehicle-mounted power battery 107 via a dc converter;
as a preferable example, the number of the plurality of groups of cameras installed around the vehicle body is four groups or more;
as a preferred illustration, the camera employs a wide angle lens;
as an illustration of an application, the wide angle lens is a 180 ° fisheye lens;
further, the magnetic field excitation system 104 is disposed at the back of the transmitting coil, and is used for spatially exciting and transmitting an electromagnetic field for guiding alignment to the upper part of the transmitting coil 111;
As an illustration, the magnetic field excitation system 104 includes: a signal generator 118, an amplification transmitting circuit 119, and a transmitting antenna; when the electromagnetic field is excited and generated, a signal generator 118 generates a sine signal, the sine signal is sent to the amplifying transmitting circuit 119 for power amplification, the amplified sine signal drives the transmitting antenna, and the generation value of the electromagnetic field strength accords with the electromagnetic field strength value allowed by national standards when the public area is wirelessly charged in design;
as an illustration, the power source of the magnetic field excitation system 104 is connected to the power grid 106, and is supplied by the power grid 106;
as an application illustration, the transmitting antenna directly adopts the transmitting coil winding of the transmitting coil 111 to act as, and excites the electromagnetic field with the frequency of 30 KHz-300 KHz;
further, the reluctance sensor groups 105 are installed at four corners of the receiving coil 115, and are used for detecting magnetic induction intensity of electromagnetic fields emitted by the magnetic field excitation system 104 distributed at each point in a parking space area;
as an illustration, the magnetic resistance sensor group adopts a structure that a power battery is connected in series with a direct current converter to supply power;
As an example, the magnetoresistive sensor group 105 includes: 12 magnetoresistive sensors mounted at four corners of the receiving coil 115, 3 for each corner;
as an illustration, each of the corners is provided with a magneto-resistive sensor along three axes X ', Y ' and Z '; the X ', Y ' and Z ' three-axis directions are real-time three-axis directions of the vehicle body;
as an illustration, four magneto-resistive sensors mounted in the X 'axis direction, whose magnetic field sensitivity direction is-X' direction, are opposite to the traveling direction of the car when the coil is directed and aligned;
as an illustration, four magneto-resistive sensors installed in the Y' axis direction, whose magnetic field sensitive directions are perpendicular to the traveling direction of the car when the coil is guided and aligned, and magneto-resistive sensors located at both sides of the receiving coil 115, whose magnetic field sensitive directions are disposed opposite to each other and respectively toward one side of the car body; as shown in fig. 3, the magnetic field sensitivity direction of the magneto-resistive sensor located in the Y 'axis direction mounted on the left side of the receiving coil 115 is-Y' direction, and the magnetic field sensitivity direction of the magneto-resistive sensor located in the Y 'axis direction mounted on the right side of the receiving coil 115 is +y' direction;
As an example, the four magneto-resistive sensors mounted in the Z' axis direction are mounted upright, i.e. perpendicular to the receiving coil 115; the magnetic field sensitivity direction of the four magnetic resistance sensors is +Z' direction, is in the same direction with the axial direction of the receiving coil winding and points to the vehicle bottom;
as an illustration, the magneto-resistive sensor employs one or a combination of anisotropic magneto-resistive elements, giant magneto-resistive elements, or tunnel magneto-resistive elements;
as an application illustration, the tunnel magneto-resistance element has the advantages of high precision, high reliability, high response speed, high sensitivity, low cost and the like, the magneto-resistance sensor adopting the tunnel magneto-resistance element can cause the resistance change of the internal magneto-resistance element under the action of a magnetic field, when the internal circuit of the magneto-resistance sensor adopts a wheatstone bridge structure, the change of the magneto-resistance intensity can cause the change of the output voltage of the internal circuit of the magneto-resistance sensor, when the internal circuit of the magneto-resistance sensor is provided with circuits such as signal amplification, filtering and the like, the output voltage of the magneto-resistance sensor is in a direct proportion relation with the magneto-resistance intensity of an external magnetic field in a linear range, and the voltage signal output by the magneto-resistance sensor is connected to the analog input end of the vehicle-mounted communication control unit for conversion, processing and analysis, so that the magneto-resistance information of corresponding position and direction can be obtained;
As an application illustration, the magnetoresistive sensor group 105 may also be installed on the outer side of the receiving coil 115, and the number and distribution of the sensors need to be kept in the same plane as the receiving coil 115 when installed at four corners of the receiving coil 115, and three magnetoresistive sensors in the three axial directions of X ' Y ' Z ' have a fixed positional relationship with one corner of the receiving coil 115, so that the coordinates obtained by the magnetoresistive sensors can be conveniently converted into the positional coordinates of the four corners of the receiving coil 115;
the wireless charging coil guiding and aligning method for the electric automobile comprises the following steps:
step one, when an automobile to be charged approaches or enters a parking space capable of being charged wirelessly, the electric automobile opens the vehicle-mounted communication control unit 112, and communication with the ground communication control unit 108 is established;
step two, the ground communication control unit 108 sends a confirmation instruction to the vehicle-mounted communication control unit 112, starts the guiding alignment operation, and sends the parking space information, the magnetic field positioning calibration value and the pairing check code value to the vehicle-mounted communication control unit 112;
as an example, the parking space information includes: the length and width of the parking space, the width of the marking line and the size data of the installation position of the transmitting coil;
As an illustration, the magnetic field positioning calibration values include: corresponding magnetic field induction B within allowable deviation range z1 Corresponding to the magnetic induction B of the magnetic field when the coils are fully aligned z0 ；
Step three, when the electric automobile is guided to be aligned, the ground communication control unit 108 controls the magnetic field excitation system to generate an electromagnetic field; the electromagnetic field is transmitted in two periods, and the electromagnetic signal does not transmit in the first period; the second cycle emits an electromagnetic field to the upper space by the transmitting coil 111; the first cycle, the magnetic sensor group 105 measures the magnetic induction of the ambient magnetic field; subtracting the environmental magnetic induction intensity of the first period from the magnetic induction intensity measured by the magnetic resistance sensor group 105 in the second period to obtain the magnetic field magnetic induction intensity distributed at the position of the electromagnetic field emitted by the transmitting coil;
step four, guiding the alignment operation of the electric automobile to adopt an image positioning mode, taking a panoramic overlook picture of the parking space by a panoramic camera 116 of an image positioning system 103, converting the picture into a gray picture by an image processing unit 117 through visual angle conversion, identifying the mark line of the parking space according to the color and geometric characteristics of the mark line of the parking space, reconstructing an outline image of the parking space through image processing and correction, and establishing an image coordinate system taking image pixels as a unit according to the resolution of the image processing unit 117 (as shown in fig. 3);
The position relationship between the transmitting coil 111 and the parking space is fixed, and the installation position of the receiving coil 115 on the electric automobile is also fixed, so that the image pixel deviation values of four corners of the receiving coil 115 and four corners of the transmitting coil in the X-Y plane can be determined according to the position of the looking-around camera 116 and the image coordinate system established by the image positioning system 103; with the center (0, 0) of the transmitting coil 111 as the origin, the image pixel coordinates of the four corners of the receiving coil 115 in the X-Y plane can be determined; the geometric dimension of the parking space is known, and according to the geometric dimension of the parking space, the actual dimension value corresponding to the image pixel can be obtained by including the dimension values such as the length, the width or the width of the mark line of the parking space, and then the actual dimension coordinates of four corners of the receiving coil 115 on the X-Y plane can be determined;
as an illustration, in order for the image localization system 103 to better identify and reconstruct a parking space, other marker bits such as lines, geometric figures, grids, etc. may be added to the parking space, and these marker bits are in a fixed positional relationship with the parking space marker lines and the transmitting coils 111;
step five, the image processing unit 117 sends the obtained four-corner coordinates of the receiving coil 115 to the vehicle-mounted communication control unit 112, and the image positioning system continuously updates the four-corner coordinates of the receiving coil 115 in the travelling process;
When the wireless charging guiding alignment operation is manually operated by a driver, the deviation between coils can be displayed through terminals such as a mobile phone, a vehicle-mounted center console and the like, and a parking path aligned by the coils is indicated according to the position deviation planning between the coils, so that driving instructions for adjusting the advancing direction such as the steering direction, the steering angle and the like are displayed for the driver;
when automatic parking or automatic driving is adopted, four-corner coordinates of the receiving coil 115 are sent to a parking system, and the parking system plans an automatic parking and realizes a coil alignment path;
by the above manual operation or the operation of the electric vehicle by the automatic parking system, the X' axis of the receiving coil 115 and the X axis of the transmitting coil 111 coincide when the electric vehicle travels, and the electric vehicle is brought closer to the transmitting coil 111 step by step;
step six, when the electric automobile approaches the position of the transmitting coil 111 gradually, the intensity of the electromagnetic field signal sent by the magnetic sensor group 105 receiving the magnetic field excitation system 104 increases gradually, and because the measurement of the looking-around camera 116 may have delay of the processing speed and some calculation deviation, and meanwhile, the external environment may have interference, when the magnetic induction intensity of the magnetic field sent by the magnetic field excitation system 104 is enough to cover all the magnetic sensor, the positioning guiding operation of the electric automobile is switched into the guiding alignment operation by adopting the coordinate data generated by the magnetic sensor group 105 in real time;
Step seven, the vehicle-mounted communication control unit 112 sends the continuously collected magnetic induction intensity, namely 4*3 magnetic induction intensity values in total in the three-axis directions of four corners X ' Y ' Z ' of the receiving coil 115, voltage values generated by the change of the magnetic induction intensity, to an analog quantity conversion circuit of the vehicle-mounted communication control unit 112 for processing, converting the voltage values into digital signals, obtaining magnetic field magnetic induction intensity in the three-axis directions of four corners of the receiving coil 115, and obtaining four three-axis coordinates of four corners of the receiving coil 115 through the distribution data model conversion of the magnetic field magnetic induction intensity;
as an illustration, the magnetic field induction intensity distribution data model can adopt a magnetic dipole model, namely, a transmitting coil is idealized into a magnetic dipole, and the magnetic field induction intensity B of each point XYZ three-axis direction in a magnetic field coverage space can be obtained x 、B y and Bz When the center (0, 0) of the transmitting coil is set as the origin of the XYZ three-axis coordinates, the magnetic induction (B) of the magnetic field in the three-axis direction for a certain point (x, y, z) x ,B y ,B z ) The following formulas are respectively provided:
wherein ,B T the fixed parameters related to the transmitting coil are related to the parameters such as the number of turns, the material, the diameter and the like of the coil, and the fixed parameters need to be calibrated in advance according to different transmitting coils;
the three-axis coordinates (X, Y, z) of the measuring points can be obtained according to the model, so that the coordinates of the four corners of the receiving coil in the X-Y plane can be continuously obtained according to the magnetic induction intensity of the three-axis magnetic field measured at the four corners of the receiving coil;
The electric automobile is driven to the four corners of the receiving coil 115 by manual operation of a driver or adjustment of the automobile by an automatic parking and driving system, the deviation between the X axis and the Y axis is reduced to be within the allowable deviation range between the coils when the wireless charging system is charged, and the electric automobile is aligned as accurately as possible;
step eight, in the final alignment stage, i.e. when the projection of the receiving coil 115 and the transmitting coil 111 start to overlap, the final alignment state can be judged or assisted by adopting the magnetic field positioning calibration value, i.e. the magnetic field induction intensity value B corresponding to the magneto-resistive sensor calibrated in advance in the Z' axis direction within the allowable coil deviation range according to the different transmitting coils 111 z1 And magnetic field induction B corresponding to the magnetoresistive sensor in the Z' axis direction when the transmitting coil 111 and the receiving coil 115 are fully aligned z0 ；
When the magnetic induction intensity of the magnetic field received by the four magnetic resistance sensors at the four corners Z' axis of the receiving coil is not lower than the standard value B z1 When the transmitting coil 111 and the receiving coil 115 are aligned, the positional deviation is considered to be within the charging allowable range; when the magnetic induction intensity of the magnetic field received by the four-angle Z' -axis sensor of the receiving coil is equal or the deviation value is minimum, and the magnetic induction intensity of the received magnetic field is not lower than the standard value B z0 When the transmit coil 111 and the receive coil 115 are considered to be perfectly aligned;
step nine, after the transmitting coil 111 is aligned with the receiving coil 115, a verification electromagnetic field is excited and transmitted through the transmitting coil 111, when four magneto-resistive sensors in the four corners Z axis all receive electromagnetic signals exceeding a certain intensity amplitude, the electromagnetic signals with long period are regarded as 1, the electromagnetic signals with short period are regarded as 0, when the binary code formed by 01 is consistent with the pairing verification code value transmitted through communication, the verification is successful, the verification process of the guiding alignment of the coils is completed, the ground communication control unit 108 sends a signal to the vehicle-mounted communication control unit 112, the wireless charging condition is confirmed to be provided, and the wireless charging operation is started.
With the rapid development of intelligent driving technology, vision systems such as a looking-around camera and the like are increasingly configured on the electric automobile, the accurate position relation between a transmitting coil and a receiving coil can be obtained when a vehicle approaches a parking space or just enters the parking space through image processing of the looking-around camera, and a travel path can be planned to guide a driver or a parking system to finish coil alignment, so that the technical problem that the alignment operation of the electric automobile is easy to fail because the electric automobile is required to approach a detection magnetic field excitation source to obtain guide data in the related technology is solved; on the other hand, the magnetic resistance sensor has high sensitivity and detection precision, high-precision coordinate analysis can be provided within the action distance of the magnetic resistance sensor, and the accuracy and the reliability of coil alignment are improved through the final alignment, inspection and verification of the coil of the magnetic resistance sensor; compared with the coil alignment operation of wireless charging in the prior art, the invention has higher alignment precision, safe and reliable operation and higher cost performance;
The above disclosure is only one specific embodiment of the present application, but the present application is not limited thereto, and any changes that can be thought by those skilled in the art should fall within the protection scope of the present application.
Claims (3)
1. The wireless charging coil guiding and aligning method for the electric automobile is characterized in that,
based on the implementation of the wireless charging coil guiding and aligning device of the electric automobile, the wireless charging coil guiding and aligning device of the electric automobile comprises: the system comprises ground emission equipment, vehicle-mounted receiving equipment, an image positioning system, a magnetic field excitation system and a magnetic resistance sensor group;
the ground emission equipment is arranged in the parking space and is electrically connected with a power supply grid; the vehicle-mounted receiving equipment is arranged at the bottom of the electric automobile and is electrically connected with the vehicle-mounted power battery;
the ground emission device includes: the ground communication control unit, the transmitting end power converter, the transmitting end resonant network and the transmitting coil; a transmitting coil winding for exciting a magnetic field is arranged in the transmitting coil;
the in-vehicle receiving apparatus includes: the system comprises a vehicle-mounted communication control unit, a receiving end resonant network, a receiving end power converter and a receiving coil; a receiving coil winding for receiving a magnetic field is arranged in the receiving coil;
The image positioning system is used for constructing a coordinate system of image pixels and guiding the electric automobile to align with the transmitting coil;
the magnetic field excitation system is arranged at the side of the transmitting coil and is powered by the power supply grid; for spatially exciting and emitting an electromagnetic field for guiding alignment to the upper side of the transmitting coil; the magnetic field excitation system comprises: a signal generator, an amplifying transmitting circuit and a transmitting antenna; when the electromagnetic field is generated by excitation, a signal generator generates a sinusoidal signal, the sinusoidal signal is sent into the amplifying transmitting circuit for power amplification, the amplified sinusoidal signal drives the transmitting antenna, and the generation value of the electromagnetic field strength accords with the electromagnetic field strength value allowed by national standard when the public area is charged in a wireless manner during design;
the magnetic resistance sensor groups are arranged at four corners of the receiving coil and are used for detecting the magnetic induction intensity of electromagnetic fields emitted by the magnetic field excitation system and distributed at each point of a parking space area;
the image positioning system includes: a looking-around camera and an image processing unit; wherein, the looking around camera includes: the cameras are arranged around the vehicle body and are respectively used for collecting images in the front, rear, left and right directions of the vehicle; after the surrounding view image of the vehicle body is obtained, a plurality of groups of cameras transmit the acquired images to an image processing unit, and a panoramic overlook picture of the surrounding environment of the vehicle is obtained after image processing, distortion correction and image stitching processing are carried out;
The transmitting antenna directly adopts a transmitting coil winding of the transmitting coil to serve as a transmitting antenna;
the magnetic resistance sensor group includes: 12 magneto-resistive sensors mounted at four corners of the receiving coil, 3 for each corner;
each angle is provided with a magnetic resistance sensor in the X ', Y ' and Z ' three-axis directions respectively; the four magnetic resistance sensors are arranged in the X 'axis direction, the magnetic field sensitivity direction of the four magnetic resistance sensors is in the-X' direction, and the four magnetic resistance sensors are opposite to the advancing direction of the automobile when the coils are guided and aligned; the four magnetic resistance sensors are arranged in the Y' axis direction, the magnetic field sensitivity directions of the four magnetic resistance sensors are perpendicular to the advancing direction of the automobile when the coils are guided and aligned, and the magnetic resistance sensors are positioned at the two sides of the receiving coil, are opposite to each other and face to one side of the automobile body respectively; the magnetic field sensitivity direction of the magneto-resistive sensor positioned in the Y 'axis direction installed on the left side of the receiving coil is in the-Y' direction, and the magnetic field sensitivity direction of the magneto-resistive sensor positioned in the Y 'axis direction installed on the right side of the receiving coil is in the +Y' direction; the four magnetic resistance sensors are arranged in the Z' axis direction and are vertically arranged, namely are vertical to the receiving coil; the magnetic field sensitivity direction of the four magnetic resistance sensors is +Z' direction, is in the same direction with the axial direction of the receiving coil winding and points to the vehicle bottom;
The wireless charging coil guiding and aligning method of the electric automobile comprises the following steps:
when an automobile to be charged approaches or enters a parking space capable of being charged in a wireless mode, the electric automobile opens a vehicle-mounted communication control unit, and communication with a ground communication control unit is established;
step two, the ground communication control unit sends a confirmation instruction to the vehicle-mounted communication control unit, starts guiding alignment operation, and sends parking space information, a magnetic field positioning calibration value and a pairing check code value to the vehicle-mounted communication control unit; the magnetic field positioning calibration value comprises: corresponding magnetic field induction B within allowable deviation range z1 Corresponding to the magnetic induction B of the magnetic field when the coils are fully aligned z0 ；
Step three, when the electric automobile is guided to be aligned, the ground communication control unit controls the magnetic field excitation system to generate an electromagnetic field; the electromagnetic field is transmitted in two periods, and the electromagnetic signal does not transmit in the first period; the second period is to emit electromagnetic field from the emitting coil to the upper space; in the first period, the magnetic induction intensity of the environment magnetic field is measured by the magnetic resistance sensor group; subtracting the magnetic induction intensity of the environmental magnetic field in the first period from the magnetic induction intensity of the environmental magnetic field measured by the magnetic resistance sensor group in the second period to obtain the magnetic induction intensity of the magnetic field distributed at the position of the electromagnetic field emitted by the transmitting coil; step four, guiding the alignment operation of the electric automobile to adopt an image positioning mode, taking a panoramic overlook picture of the parking space by a panoramic camera of an image positioning system, converting the picture into a gray picture by an image processing unit through visual angle conversion, identifying the mark line of the parking space according to the color and geometric characteristics of the mark line of the parking space, reconstructing an outline image of the parking space through image processing and correction, and establishing an image coordinate system taking image pixels as units according to the resolution of the image processing unit;
The position relation between the transmitting coil and the parking space is fixed, the installation position of the receiving coil on the electric automobile is also fixed, and the image pixel deviation values of four corners of the receiving coil and four corners of the transmitting coil on an X-Y plane can be determined according to the position of the looking-around camera and an image coordinate system established by the image positioning system; the image pixel coordinates of four corners of the receiving coil in the X-Y plane can be determined by taking the center (0, 0) of the transmitting coil as an origin; the geometric dimension of the parking space is known, and according to the geometric dimension of the parking space, the actual dimension value corresponding to the image pixel can be obtained by including the length, the width or the width dimension value of the mark line of the parking space, so that the actual dimension coordinates of four corners of the receiving coil on the X-Y plane can be determined;
step five, the image processing unit sends the obtained four-angle coordinates of the receiving coil to the vehicle-mounted communication control unit, and the image positioning system continuously updates the four-angle coordinates of the receiving coil in the travelling process;
when the wireless charging guiding alignment operation is manually operated by a driver, displaying deviation among coils through a terminal, planning according to the position deviation among the coils, indicating a parking path aligned by the coils, and displaying driving instructions for adjusting the travelling direction for the driver; the terminal comprises a mobile phone or a vehicle-mounted center console; the driving instruction for adjusting the traveling direction comprises a steering direction or a steering angle;
When the automatic parking is adopted, four-corner coordinates of the receiving coil are sent to a parking system, and the parking system plans an automatic parking and realizes the path of coil alignment;
the electric automobile is operated by the manual operation or the automatic parking system, so that the X' axis of the receiving coil and the X axis of the transmitting coil are overlapped when the electric automobile runs, and the electric automobile is gradually close to the transmitting coil;
step six, when the electric automobile approaches the position of the transmitting coil gradually, the intensity of an electromagnetic field signal sent by the magnetic resistance sensor group receiving magnetic field excitation system is increased gradually, and as the measurement of the looking-around camera is possibly delayed in processing speed and some calculation deviation, the external environment is possibly interfered, and when the magnetic field magnetic induction intensity sent by the magnetic field excitation system is enough to cover all the magnetic resistance sensors, the positioning and guiding operation of the electric automobile is switched into the guiding and aligning operation by adopting coordinate data generated by the magnetic resistance sensor group in real time;
step seven, the vehicle-mounted communication control unit sends the continuously collected magnetic induction intensity, namely 4*3 magnetic induction intensity values in total in the three-axis directions of four corners X ' Y ' Z ' of the receiving coil, voltage values generated by the change of the magnetic induction intensity, to an analog quantity conversion circuit of the vehicle-mounted communication control unit for processing, converting the voltage values into digital signals, obtaining magnetic field magnetic induction intensity in the three-axis directions of four corners of the receiving coil, and obtaining four three-axis coordinates of four corners of the receiving coil through the conversion of a distribution data model of the magnetic field magnetic induction intensity;
The electric automobile is driven to the four corners of the receiving coil through manual operation of a driver or adjustment of the automobile by automatic parking, the deviation of the X axis and the Y axis is reduced to the allowable deviation range between the coils when the wireless charging system is charged, and the electric automobile is aligned as accurately as possible;
step eight, in the final alignment stage, that is, when the projection of the receiving coil and the transmitting coil begin to overlap, the final alignment state is judged or assisted by adopting a magnetic field positioning calibration value, that is, the magnetic field induction intensity value B corresponding to the magneto-resistance sensor in the Z' axis direction within the allowable coil deviation range is calibrated in advance according to different transmitting coils z1 And a magnetic field corresponding to the magnetoresistive sensor in the Z' axis direction when the transmitting coil and the receiving coil are fully alignedMagnetic induction intensity B z0 ；
When the magnetic induction intensity of the magnetic field received by the four magnetic resistance sensors at the four corners Z' axis of the receiving coil is not lower than the standard value B z1 When the transmitting coil and the receiving coil are aligned, the position deviation is considered to be within the allowable range of charging; when the magnetic induction intensity of the magnetic field received by the four-angle Z' -axis sensor of the receiving coil is equal or the deviation value is minimum, and the magnetic induction intensity of the received magnetic field is not lower than the standard value B z0 When the transmit coil and the receive coil are considered to be perfectly aligned;
and step nine, after the transmitting coil is aligned with the receiving coil, exciting and transmitting a verification electromagnetic field through the transmitting coil, when four magnetic resistance sensors in the Z' axes of four corners all receive electromagnetic signals exceeding a certain intensity amplitude, taking the electromagnetic signal with a long period as 1 and the electromagnetic signal with a short period as 0, if the binary code formed by 01 is consistent with the pairing verification code value transmitted through communication, the verification is successful, the verification process of the guiding alignment of the coil is completed, and a ground communication control unit transmits a signal to a vehicle-mounted communication control unit to confirm that the vehicle-mounted communication control unit has wireless charging conditions and starts wireless charging operation.
2. The electric vehicle wireless charging coil guide alignment method according to claim 1, wherein the parking space information includes: the length and width of the parking space, the width of the marking line and the size data of the installation position of the transmitting coil.
3. The method for guiding and aligning wireless charging coils of electric vehicles according to claim 1, wherein in order to enable the image positioning system to better identify and reconstruct a parking space, a flag bit is added in the parking space, wherein the flag bit is one of a straight line, a geometric figure and a grid, and the flag bits are in a fixed position relation with a parking space flag line and a transmitting coil;
The distribution data model of the magnetic field induction intensity adopts a magnetic dipole model, namely, a transmitting coil is idealized into a magnetic dipole, so that the magnetic field induction intensity of each point XYZ three-axis direction in a magnetic field coverage space can be obtainedDegree B x 、B y and Bz When the center (0, 0) of the transmitting coil is set as the origin of the XYZ three-axis coordinates, the magnetic induction (B) of the magnetic field in the three-axis direction for a certain point (x, y, z) x ,B y ,B z ) The following formulas are respectively provided:
wherein ,B T for the fixed parameters related to the transmitting coil, the number of turns, the material and the diameter of the coil are related, and the transmitting coil is required to be calibrated in advance according to different transmitting coils;
the three-axis coordinates (X, Y, z) of the measurement points can be obtained according to the model, so that the coordinates of the four corners of the receiving coil in the X-Y plane can be continuously obtained according to the magnetic induction intensity of the three-axis magnetic field measured at the four corners of the receiving coil.
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