Position and foreign object mixing detection system and electric vehicle wireless charging control method

Abstract

The present invention discloses a position and foreign object mixed detection system and an electric vehicle wireless charging control method. The system includes a transmitting coil on the primary side and a receiving coil on the secondary side, and is characterized in that: an active excitation coil is arranged above the transmitting coil, a detection coil array is arranged above the active excitation coil, and at least one beacon coil is also arranged on the secondary side. The active excitation coil is wound into m*n uniformly distributed squares, and when current passes through, the magnetic field directions generated in two adjacent squares are opposite. The detection coil array includes m*n detection coils, and each detection coil correspondingly covers a square area in the active excitation coil, where m and n are positive integers greater than 2. The effect is that the system has a simple structure and clear logic, can better realize the position detection of the receiving coil and the detection of metal foreign objects, and the two systems do not affect each other.

Description

Technical Field

[0001] The present invention relates to wireless power transmission technology, and in particular to a position and foreign matter hybrid detection system and an electric vehicle wireless charging control method. Background Art

[0002] Wireless Power Transfer (WPT) technology has attracted widespread attention from the academic community due to its convenience, safety, and promising research prospects. Wireless charging for electric vehicles is one of the most promising applications of WPT, but its large-scale deployment is still hampered by issues such as transmission efficiency and system security.

[0003] Most existing receiving coil position and metal foreign body mixed detection systems are incompatible with each other. Therefore, the detection devices of most solutions are large in size, have poor compatibility, and are easily affected by the environment. Therefore, a new design method is needed to achieve high-precision receiving coil position and metal foreign body mixed detection in electric vehicle wireless charging systems at low cost and high stability. Summary of the Invention

[0004] In view of this, the primary purpose of the present invention is to provide a hybrid position and foreign object detection system to achieve high-precision detection of the receiving coil position and sensitive detection of metal foreign objects, so as to replace the existing solution.

[0005] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0006] A hybrid position and foreign object detection system includes a primary-side transmitting coil and a secondary-side receiving coil. The key features are: an active excitation coil is arranged above the transmitting coil, a detection coil array is arranged above the active excitation coil, and at least one beacon coil is also arranged on the secondary side. The active excitation coil is wound into m*n evenly distributed squares. After current passes through, the magnetic fields generated in two adjacent squares are in opposite directions. The detection coil array includes m*n detection coils, each detection coil correspondingly covers a square area in the active excitation coil, and m and n are positive integers greater than 2.

[0007] Optionally, the transmitting coil and the receiving coil operate at a first resonant frequency to achieve energy transmission, and the beacon coil, the active excitation coil and the corresponding detection coil in the detection coil array operate at a second resonant frequency to achieve position and foreign object mixed detection.

[0008] Optionally, the first resonant frequency is 85 kHz and the second resonant frequency is 3 MHz.

[0009] Optionally, the active excitation coil is wound to form 8×10 coil squares, and the size of each coil square is 63 mm×59 mm; the detection coil array also includes 8×10 detection coils, and the size of each detection coil is 63 mm×59 mm.

[0010] Optionally, the beacon coil is a rectangular coil and is located around the receiving coil. Each beacon coil has 4 turns and the size is 20 mm×20 mm.

[0011] Optionally, the beacon coil is connected to a beacon circuit, and the beacon circuit includes a DC signal source, a half-bridge inverter, and an LCC resonance compensation network.

[0012] Optionally, the detection circuit includes an RLC resonance circuit, a high-pass filter circuit, and a rectifier filter circuit. The RLC resonance circuit is a low-quality factor circuit that resonates at the second resonance frequency, and the high-frequency gain of the high-pass filter circuit at the second resonance frequency is more than 10 times the gain at the first resonance frequency.

[0013] Optionally, the rectifier filter circuit includes a diode and an RC filter, and the voltage amplitude output by the high-pass filter circuit is more than 5 times the diode voltage drop value.

[0014] Based on the above system, the present invention further provides an electric vehicle wireless charging control method, which is characterized in that: using the position and foreign object hybrid detection system described above, before the vehicle is parked, first start the active excitation coil and the detection coil array to work to achieve foreign object detection before starting up. If a foreign object exists, an alarm is issued; if there is no foreign object or the metal foreign object is removed, start the beacon coil and the detection coil array to work to achieve position detection, and adjust the vehicle according to the measured position; when the vehicle position is aligned, then start the transmitting coil and the receiving coil to work to achieve energy transmission, and at the same time, the active excitation coil and the detection coil array perform foreign object detection again. When a foreign object is found, the machine is stopped and an alarm is issued.

[0015] Optionally, determine the number of beacon coils by detecting the detection signals of each detection coil in the detection coil array, determine the power level of the receiving coil according to the number of beacon coils, and then start the transmitting coil to achieve energy transmission according to the corresponding power level after the vehicle position is aligned.

[0016] The remarkable effects of the present invention are:

[0017] The system structure is simple and the logic is clear, which can better realize the position detection of the receiving coil and the detection of metal foreign objects, and the two systems do not affect each other. Description of the Drawings

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0019] Figure 1 Schematic diagram of the coupling mechanism structure of the system in a specific embodiment of the present invention;

[0020] Figure 2 For Figure 1 exploded view;

[0021] Figure 3 Schematic circuit diagram of the beacon circuit in a specific embodiment of the present invention;

[0022] Figure 4 Schematic circuit diagram of the detection circuit in a specific embodiment of the present invention;

[0023] Figure 5 System control flowchart in a specific embodiment of the present invention.

[0024] Reference numerals: 1 - transmitting coil, 2 - receiving coil, 3 - beacon coil, 4 - active excitation coil, 5 - detection coil array. Detailed implementation manners

[0025] The following will describe in detail the embodiments of the present invention. The examples of the embodiments are shown in the drawings, where the same or similar reference numerals represent the same or similar elements or elements with the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present invention, and should not be construed as a limitation to the present invention.

[0026] In the description of the present invention, "a plurality of" means two or more, unless otherwise specifically defined.

[0027] As Figure 1 、 Figure 2 shown, this embodiment provides a position and foreign object mixed detection system, including a transmitting coil 1 on the primary side and a receiving coil 2 on the secondary side. A plurality of beacon coils 3 are arranged around the receiving coil 2. Each beacon coil 3 is rectangular, has 4 turns, and the size is 20mm * 20mm. An active excitation coil 4 is arranged above the transmitting coil 1, and a detection coil array 5 is arranged above the active excitation coil 4;

[0028] Through Figure 2It can be seen that in this embodiment, the active excitation coil 4 is wound into 8×10 uniformly distributed squares, the size of each coil square is 63mm×59mm, and the magnetic field directions generated in two adjacent squares are opposite after the current passes through; correspondingly, the detection coil array 5 includes 8×10 detection coils, the size of each detection coil is 63mm×59mm, and each detection coil correspondingly covers a square area in the active excitation coil 4.

[0029] During specific implementation, the transmitting coil 1 and the receiving coil 2 work at the first resonant frequency to achieve energy transfer, and the beacon coil 3, the active excitation coil 4 and the corresponding detection coils in the detection coil array 5 work at the second resonant frequency to achieve position and foreign object mixed detection. Based on the specifications of WPT3 and Z2 stipulated in the SAE J2954 standard, the first resonant frequency is 85 kHz. In order to reduce the mutual influence between the energy transfer and the position detection system, the second resonant frequency is 3 MHz.

[0030] The function of the beacon coil 3 is to transmit its own position to the detection coil on the ground side for positioning. Since the current of the receiving coil is very high when the electric vehicle wireless charging system works, when designing the beacon coil, the opposite ends of the two beacon coils on the long side are connected to generate a pair of reverse induced electromotive forces to cancel the induced voltage of the beacon coil when the power system works; similarly, for the active excitation coil on the ground side, its function is to generate a high-frequency magnetic field to jointly detect metal foreign objects with the detection coil. Since the current of the transmitting coil is very high when the electric vehicle wireless charging system works, when designing the active excitation coil, the magnetic field directions generated by each adjacent square of the active excitation coil are opposite, and 80 squares are evenly divided into two groups of 40 each, so as to ensure that the induced voltage on the active excitation coil is basically zero and ensure the safety of the system; for the detection coil on the ground side, its function is foreign object detection and position detection. Since the current of the transmitting coil is very high when the electric vehicle wireless charging system works, when designing the detection coil, it is necessary to reduce the number of turns and design the corresponding RLC parameters.

[0031] The beacon coils on the vehicle side are connected in series in opposite directions in pairs along the long side. To improve the reliability of the system, they are set to work in a time-sharing manner. At the same vehicle parking position, the detection coil group on the ground side will obtain two sets of voltage data to judge the center position of the receiving coil. The voltage data of the detection coil group is used to calculate the corresponding coordinates of the beacon coil on the ground side through weight calculation. The center coordinates of the receiving coil can be calculated by the known relative distance between the center of the beacon coil and the center of the receiving coil. The x and y coordinates of the center of the receiving coil obtained from the four beacon coils are averaged to obtain the final center coordinates of the receiving coil.

[0032] Combined with Figure 3As shown, in specific implementation, the beacon coil 3 is connected to a beacon circuit, and the beacon circuit includes a DC signal source, a half-bridge inverter, and an LCC resonant compensation network.

[0033] Combined with Figure 4 As shown, the detection circuit includes an RLC resonant circuit, a high-pass filter circuit, and a rectifier filter circuit. The RLC resonant circuit is a low-quality factor circuit that resonates at the second resonant frequency. The high-frequency gain of the high-pass filter circuit at the second resonant frequency is more than 10 times the gain at the first resonant frequency. The rectifier filter circuit includes a diode and an RC filter, and the voltage amplitude output by the high-pass filter circuit is more than 5 times the diode voltage drop value.

[0034] The active excitation coil on the ground side generates a high-frequency magnetic field of 3 MHz in each grid. This magnetic field is detected by the detection coil installed above the active excitation, and a constant voltage signal is generated. When a metal foreign object invades, the eddy current of the metal foreign object will cause the magnetic flux passing through the detection coil to change, resulting in a decrease in the coil induced electromotive force and induced current. Moreover, the reflection impedance generated by the metal foreign object on the detection coil will cause the detection coil to deviate from the resonant region, resulting in a decrease in the coil induced current. Therefore, the invasion of metal foreign objects can be detected by detecting the change in the induced current of the detection coil.

[0035] Combined with Figure 5 As shown, this embodiment also provides an electric vehicle wireless charging control method. Using the position and foreign object hybrid detection system described above, before the vehicle is parked, the active excitation coil and the detection coil array are first started to work to achieve foreign object detection before startup. If a foreign object exists, an alarm is issued; if there is no foreign object or the metal foreign object is removed, the beacon coil and the detection coil array are started to work to achieve position detection, and the vehicle is adjusted according to the measured position; when the vehicle position is aligned, the transmitting coil and the receiving coil are then started to work to achieve energy transfer, and at the same time, the active excitation coil and the detection coil array perform foreign object detection again. When a foreign object is found, the machine is stopped and an alarm is issued.

[0036] Through Figure 5It can be seen that the receiving coil position and metal foreign body mixed detection system need to work in a certain order to ensure that the system can well realize foreign body detection and receiving coil position detection: before the vehicle stops, the active excitation coil and the detection coil group work intermittently to realize the detection of metal foreign bodies under the premise of reducing system energy consumption. When the foreign body is found, an alarm is issued and the alarm is lifted after the foreign body is removed; if there is no foreign body or the metal foreign body is removed and the foreign body detection before restart is performed, wait for the vehicle to enter the area for position detection. When the vehicle stops above the detection coil, the beacon coil group and the detection coil group work to detect the position of the receiving coil and adjust the vehicle according to the measured position; when the vehicle adjusts its position, the transmitting coil and the receiving coil work to transfer energy. At this time, the active excitation coil and the detection coil group work to detect foreign bodies. If a foreign body is found, the system will stop and issue an alarm.

[0037] In specific implementation, different numbers of beacon coils can be set on the receiving coil 2 according to different vehicle power levels. The number of beacon coils is determined by detecting the detection signals of each detection coil in the detection coil array, and the power level of the receiving coil is determined according to the number of beacon coils. After the vehicle position is aligned, the transmitting coil is started to realize energy transmission according to the corresponding power level.

[0038] It is not difficult to see that the hybrid position and foreign object detection system and electric vehicle wireless charging control method proposed in the present invention can eliminate various influences generated by the power system and sensitively detect the center position of the receiving coil without generating any additional loss, thereby ensuring efficient power transmission.

[0039] Finally, it should be noted that what is disclosed above is only a preferred embodiment of the present invention, and of course it cannot be used to limit the scope of rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment are implemented, and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A position and foreign object mixed detection system, comprising a transmitting coil on the primary side and a receiving coil on the secondary side, characterized in that: An active excitation coil is disposed above the transmitting coil, a detection coil array is disposed above the active excitation coil, and at least one beacon coil is further disposed on the secondary side. The active excitation coil is wound into m*n uniformly distributed squares. When current passes through, the magnetic field directions generated in two adjacent squares are opposite. The detection coil array includes m*n detection coils, and each detection coil correspondingly covers a square area in the active excitation coil. m and n are positive integers greater than 2; The beacon coil is connected to a beacon circuit, and the beacon circuit includes a DC signal source, a half-bridge inverter, and an LCC resonant compensation network; the beacon coil is used to transmit its own position to the detection coil on the ground side for positioning; the active excitation coil is used to generate a high-frequency magnetic field in combination with the detection coil for metal foreign object detection; The detection system includes a detection circuit, and the detection circuit includes an RLC resonant circuit, a high-pass filter circuit, and a rectifier filter circuit. The detection system determines the number of beacon coils based on the detection signals of the respective detection coils in the detection coil array, determines the power level of the receiving coil according to the number of beacon coils, and then starts the transmitting coil to achieve energy transfer at the corresponding power level after the vehicle position is aligned.

2. The position and foreign object mixed detection system according to claim 1, wherein: The transmitting coil and the receiving coil operate at a first resonant frequency to achieve energy transfer, and the beacon coil, the active excitation coil, and the corresponding detection coil in the detection coil array operate at a second resonant frequency to achieve a hybrid detection of position and foreign objects.

3. The position and foreign object mixed detection system according to claim 2, characterized in that: The first resonant frequency is 85 kHz, and the second resonant frequency is 3 MHz.

4. The position and foreign object mixing detection system according to claim 3, characterized in that: The active excitation coil is wound to form 8*10 coil squares, and the size of each coil square is 63 mm * 59 mm; the detection coil array also includes 8*10 detection coils, and the size of each detection coil is 63 mm * 59 mm.

5. The position and foreign object mixed detection system according to claim 1 or 2 or 4, characterized in that: The beacon coil is a rectangular coil and is located around the receiving coil. Each beacon coil has 4 turns and a size of 20 mm * 20 mm.

6. The position and foreign object mixed detection system according to claim 2 or 3, characterized in that: The RLC resonant circuit is a low-quality factor circuit that resonates at the second resonant frequency, and the high-frequency gain of the high-pass filter circuit at the second resonant frequency is more than 10 times the gain at the first resonant frequency.

7. The position and foreign object mixed detection system according to claim 6, characterized in that: The rectifier filter circuit includes a diode and an RC filter, and the voltage amplitude output by the high-pass filter circuit is more than 5 times the diode voltage drop value.

8. A wireless charging control method for an electric vehicle, characterized in that: Adopting the position and foreign object hybrid detection system according to any one of claims 1-7, before the vehicle parks, first start the active excitation coil and the detection coil array to work for foreign object detection before starting. If a foreign object exists, an alarm is issued; if there is no foreign object or the metal foreign object is removed, start the beacon coil and the detection coil array to work for position detection, and adjust the vehicle according to the measured position; when the vehicle position is aligned, then start the transmitting coil and the receiving coil to work for energy transfer, and at the same time, the active excitation coil and the detection coil array perform foreign object detection again. When a foreign object is found, the machine is stopped and an alarm is issued.

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