Wireless charging method for electric vehicle

Abstract

A wireless charging method for an electric vehicle according to the present invention comprises the steps of: measuring an alignment ratio between a transmitter and a receiver when the receiver is detected; entering a foreign object detection mode when the alignment ratio is greater than or equal to a reference ratio; measuring a power loss ratio while performing power transmission in the foreign object detection mode; determining whether a foreign object is present on the basis of the alignment ratio and the power loss ratio; and entering a low-speed or high-speed charging mode when it is determined that the foreign object is absent. According to the wireless charging method for a vehicle according to the present invention, it is possible to effectively detect foreign substances during wireless charging and safely perform wireless charging, and it is possible to minimize the risk of heating and fires caused by foreign substances while improving the efficiency of charging speed through various charging modes.

Description

Wireless charging method for electric vehicles

[0001] The present invention relates to wireless power transmission technology, and more particularly, to a wireless charging method for an electric vehicle.

[0002] Advances in battery, electrical, and electronic technology, and communications technology have significantly improved the performance, efficiency, and user convenience of electric vehicles. Combined with environmental concerns and energy conservation efforts, the proliferation of electric vehicles continues to accelerate. The increased energy density of lithium-ion batteries has enabled increased battery capacity, significantly extending the driving range of electric vehicles. Furthermore, advances in inverters and converters have enabled more effective control of electric motors, improving the efficiency of power transfer from the battery to the motor. Furthermore, advancements in energy management systems within electric vehicles and the use of lightweight materials have reduced vehicle weight and improved battery performance efficiency.

[0003] In addition, the recent expansion of charging infrastructure has fueled consumer interest in electric vehicles. Currently, the dominant charging system is wired charging, which recharges electric vehicles using charging cables. Wired charging presents numerous challenges, including complex charging equipment, the risk of electric shock and fire, high maintenance costs, and poor compatibility between charging terminals and charging cables. Consequently, active research and development is underway on wireless charging, which offers superior performance in speed and convenience over wired charging.

[0004] Figure 1 is a general schematic diagram of an electric vehicle wireless charging system. The system consists of a ground assembly (GA) and a vehicle assembly (VA). The ground assembly comprises a power supply unit and a transmitter (transmitting coil), while the vehicle assembly comprises a receiver (receiving coil) and a rectifier.

[0005] In more detail, the ground assembly typically includes a line filter, a power factor correction (PFC) circuit, and an inverter. The line filter and power factor correction circuit minimize reactive power by adjusting the power factor (PF) and total harmonic distortion (THD) to provide high power quality, and the inverter converts the DC output of the power factor correction circuit into AC power and supplies it to the transmitter. When the AC power supplied from the inverter is applied to the coil of the transmitter, an AC magnetic field is generated according to Faraday's law.

[0006] When the magnetic field of the AC supplied from the transmitter is linked, the AC current is conducted to the receiver of the vehicle assembly, and the rectifier connected to the receiver rectifies the AC power into DC power and supplies it to the battery.

[0007] In this way, the wireless charging system for electric vehicles enables high-power power transmission in a non-contact manner, and can solve various problems associated with existing wired charging methods.

[0008] Wireless charging methods include magnetic induction, electromagnetic wave, and magnetic resonance. For electric vehicle wireless charging, the magnetic resonance method is more effective because the transmitter and receiver are separated. The transmitter transmits power to the receiver using strong electromagnetic waves of hundreds of volts. Therefore, any foreign matter between the transmitter and receiver, or the introduction of such matter during charging, poses a high risk of overheating or fire. Unlike mobile wireless charging, which has a relatively small power output, the presence of foreign matter is a critical issue for vehicle wireless charging, and this issue must be addressed as a prerequisite for ensuring the stability and viability of electric vehicle wireless charging.

[0009] [Patent Document]

[0010] Korean Patent Publication No. 10-2605549 (registered on November 20, 2023)

[0011] The present invention has been developed in consideration of the aforementioned technical challenges, and its purpose is to provide a wireless charging method for vehicles capable of effectively detecting foreign substances and safely performing wireless charging. Furthermore, the present invention provides a wireless charging method for vehicles capable of improving charging speed efficiency through various charging modes while reducing the risk of heat generation and fire caused by foreign substances.

[0012] A wireless charging method for a vehicle according to the present invention comprises the steps of: measuring an alignment ratio between a transmitter and a receiver when a receiver is detected; entering a foreign matter detection mode when the alignment ratio is equal to or greater than a reference ratio; measuring a power loss ratio while performing power transmission in the foreign matter detection mode; determining the presence or absence of a foreign matter based on the alignment ratio and the power loss ratio; and entering a low-speed or high-speed charging mode when it is determined that the foreign matter is absent.

[0013] And, the step of determining the presence or absence of the foreign substance can determine the presence or absence of the foreign substance based on the alignment ratio section between the transmitter and the receiver and the threshold value of the power transmission ratio for each of the alignment ratio sections.

[0014] In addition, the method may further include a step of constructing a look-up table (LUT) including the alignment ratio section and the threshold value; and a step of determining that the foreign substance is present when the power loss ratio is greater than or equal to the threshold value.

[0015] In addition, the threshold value can be set based on the allowable loss ratio and the basic resonance loss ratio in each of the alignment ratio sections.

[0016] In addition, the step of determining that the foreign substance exists may be performed by repeatedly determining whether the power loss ratio is greater than or equal to the threshold value multiple times, and if the power loss ratio is greater than or equal to the threshold value for N or more consecutive times, it may be determined that the foreign substance exists.

[0017] And, it may further include a step of re-measuring the power loss ratio while performing power transmission in the low-speed or high-speed charging mode; and a step of determining whether foreign substances have penetrated based on the re-measured power loss ratio and the alignment ratio.

[0018] In addition, if it is determined that the foreign substance has penetrated in the low-speed or high-speed charging mode, the step of measuring the amount of heat generated in the low-speed or high-speed charging mode may be further included; and if the amount of heat generated is greater than or equal to a reference amount of heat generated, the step of stopping charging in the low-speed or high-speed charging mode may be further included.

[0019] And, if it is determined that the foreign substance has penetrated in the low-speed or high-speed charging mode, the step of stopping the low-speed or high-speed charging mode; and the step of re-entering the foreign substance detection mode may be further included.

[0020] Additionally, the amount of power supplied to the transmitter in the foreign substance detection mode may be less than the amount of power supplied to the transmitter in the low-speed or high-speed charging mode.

[0021] And, the amount of power supplied to the transmitter in the low-speed charging mode may be less than the amount of power supplied to the transmitter in the high-speed charging mode.

[0022] In addition, if the alignment ratio is less than the reference ratio, the method may further include a step of re-measuring the alignment ratio of the transmitter and the receiver at a preset cycle.

[0023] According to the wireless charging method for a vehicle according to the present invention, foreign substances can be effectively detected during wireless charging, wireless charging can be safely performed, and the efficiency of charging speed can be improved through various charging modes, while minimizing the risk of heat generation and fire caused by foreign substances.

[0024] Figure 1 is a general conceptual diagram of an electric vehicle wireless charging system.

[0025] Figure 2 is a configuration of an electric vehicle wireless charging system according to the present invention.

[0026] Figure 3 is a flow chart of a wireless charging method for an electric vehicle according to the present invention.

[0027] FIGS. 4a and 4b are drawings for explaining the measurement of the alignment ratio in the wireless charging method for an electric vehicle according to the present invention.

[0028] Figure 5 is a conceptual diagram schematically illustrating the flow chart of Figure 3.

[0029] FIG. 6 is a wireless charging method for an electric vehicle according to the present invention, and illustrates a subsequent process of the flowchart of FIG. 3.

[0030] FIG. 7 is a wireless charging method for an electric vehicle according to the present invention, and illustrates a subsequent process of the flowchart of FIG. 6.

[0031] Figure 8 is a flowchart of a wireless charging method for an electric vehicle according to another embodiment of the present invention.

[0032] Figure 9 is a flowchart of a wireless charging method for an electric vehicle according to another embodiment of the present invention.

[0033] The detailed description of the present invention, which follows, refers to the accompanying drawings, which illustrate specific embodiments in which the present invention may be practiced. These embodiments are described in sufficient detail to enable those skilled in the art to practice the present invention. It should be understood that the various embodiments of the present invention, while different from each other, are not necessarily mutually exclusive. For example, specific shapes, structures, and characteristics described herein may be implemented in other embodiments without departing from the spirit and scope of the present invention.

[0034] Furthermore, it should be understood that the position or arrangement of individual components within each disclosed embodiment may be modified without departing from the spirit and scope of the present invention. Therefore, the following detailed description is not intended to be limiting, and the scope of the present invention, if properly described, is defined solely by the appended claims, along with the full scope equivalents thereof. Similar reference numerals in the drawings designate the same or similar functions throughout the various aspects.

[0035] FIG. 2 is a configuration of a wireless charging system for electric vehicles according to the present invention. In the wireless charging system for electric vehicles, a transmitter (100) is disposed on the wireless charger side, and a receiver (200) is disposed on the vehicle (V) side. Generally, the transmitter (100) may be embedded in the floor of a charging station, fixed to the ground, or may be provided so as to be movable to a position facing the receiver (200) when the vehicle (V) stops at the charging station. In either case, the transmitter (100) and the receiver (200) may be spaced apart by a predetermined distance (D). The predetermined distance (D) may be determined according to the position of the transmitter (100), the height of the floor surface of the vehicle (V), the size of the tires, etc. However, in one embodiment, a device for controlling the vertical movement of the transmitter (100) is provided, and the height of the transmitter (100) is adjusted by the device, so that the predetermined position (D) can be freely set.

[0036] Energy transfer from a transmitter (100) to a receiver (200) can be achieved by magnetic resonance. That is, when the transmitting coil of the transmitter (100) and the receiving coil of the receiver (200) resonate at the same frequency, power is wirelessly transmitted, and at this time, transmission efficiency is maximized. Accordingly, the transmitting coil and the receiving coil have the same resonant frequency.

[0037] When power is supplied to the transmitting coil of the transmitter (100) from a grid or power supply, a current is induced, generating a strong magnetic field. The generated magnetic field spreads into the space around the receiving coil, and the receiving coil of the receiver (200) resonates at the same frequency to convert the magnetic field into electrical energy. Specifically, the alternating current generated in the receiving coil of the receiver (200) is converted into direct current through a converter (210) and stored in a battery (220).

[0038] The magnetic resonance method is most efficient when the transmitting coil and the receiving coil maintain a certain distance, and for this purpose, it is important to accurately position the receiver (200) relative to the transmitter (100). In addition, the power transmission efficiency according to the distance or angle may be determined depending on the design of the system. Meanwhile, in order to efficiently perform wireless charging and correct the safety of wireless charging, various sensors and communication systems not shown in FIG. 2 may be included. For example, a wireless communication system (device) for exchanging information with a vehicle (V), monitoring the charging status, etc. may be provided, and an image sensor, an ultrasonic sensor, an infrared sensor, an RF sensor, etc. may be provided to check the alignment or alignment ratio of the transmitter (100) and the receiver (200).

[0039] Figure 3 is a flow chart of a wireless charging method for an electric vehicle according to the present invention.

[0040] First, it is determined whether a receiver is detected in standby mode (S300 and S305). If the receiver is not detected (S305-NO), the system continues to monitor whether a receiver is detected in standby mode (S300). If a receiver is detected (S305-YES), the alignment ratio between the transmitter and receiver is measured (S310). A state in which a receiver is detected may mean that a vehicle has entered an area where a transmitter is deployed, and the receiver and transmitter are positioned opposite each other.

[0041] FIGS. 4a and 4b are drawings for explaining the measurement of the alignment ratio in the wireless charging method for an electric vehicle according to the present invention.

[0042] First, referring to Fig. 4a, the alignment state of the transmitter (100) and receiver (200) placed in the wireless charging area may vary depending on the position, posture, etc. of the vehicle. At this time, if the state in which the transmitter (100) and receiver (200) completely overlap is defined as having an alignment ratio of 100%, the alignment ratio may decrease if the alignment is misaligned.

[0043] More specifically, assuming that the areas of the transmitter (100) and the receiver (200) are the same, the alignment ratio may be the ratio of the overlapping area (the hatched area in FIG. 4) to the corresponding areas. If the areas of the transmitter (100) and the receiver (200) are different, the alignment ratio may be the ratio of the overlapping area to the smaller area of ​​the two. In FIG. 4A, the transmitter (100) and the receiver (200) are illustrated as rectangular pads for ease of understanding, but they may be formed in other shapes.

[0044] Although FIG. 4a illustrates alignment ratio measurement based on area, in other embodiments alignment ratio measurement may be possible based on X-axis and / or Y-axis distance, or distance and / or phase difference between coils.

[0045] Referring to FIG. 4b, the power loss ratio may vary depending on the distance (Dx) that the center point of the coil of the receiver (200) is misaligned in the X-axis direction and / or the distance (Dy) that the center point of the coil of the transmitter (100) is misaligned in the Y-axis direction. In other words, the wireless charging efficiency may be determined based on the distance (Dx) that is misaligned in the X-axis direction and / or the distance (Dy) that is misaligned in the Y-axis direction, and in the present invention, the alignment ratio between the transmitter (100) and the receiver (200) is measured based on this, and can be used as a basis for determining the presence or absence of a foreign substance. In another embodiment, the alignment ratio may be measured based on the distance (D) between the center points of the coils and / or the phase (θ) of the coils. The distance (D) between the center points of the coils of the transmitter (100) and the coils of the receiver (200) and / or the phase (θ) between each coil may affect the power loss ratio.

[0046] In other words, the wireless charging efficiency can be measured based on the alignment ratio based on the distance (D) between the coil centers of the transmitter (100) and the receiver (200) and / or the phase (θ) between the coils, and can be used as a basis for determining the presence or absence of foreign matter.

[0047] In Fig. 4b, the transmitter (100) and receiver (200) are depicted as circular pads for ease of understanding, but they may be formed in other shapes.

[0048] Determining the alignment ratio between the transmitter (100) and the receiver (200) can be accomplished in various ways. For example, the alignment ratio between the transmitter (100) and the receiver (200) can be determined using an ultrasonic sensor. That is, the alignment status can be confirmed by measuring the distance between a plurality of points on the transmitter (100) and a plurality of points on the receiver (200) using the ultrasonic sensor. Using an ultrasonic sensor, the alignment ratio can be determined with high accuracy and can exhibit stable performance in various environments.

[0049] As another example, the alignment ratio can be determined using a camera and image recognition technology. Specifically, by using images acquired from a camera positioned in a certain area of ​​a vehicle or charging station and image recognition technology, the positions of the transmitter (100) and receiver (200) can be acquired. Once the precise positions of the transmitter (100) and / or receiver (200) are identified using a computer vision algorithm, the vehicle can be guided to that location. Specifically, the identified location can be visualized in real time and displayed on a display within the charging station or vehicle, thereby guiding the vehicle to increase the alignment ratio.

[0050] As another example, the alignment ratio can be determined using Radio Frequency Identification (RFID) and Near Field Communication (NFC). That is, an RFID tag and reader can be installed in the transmitter (100) and receiver (200) to check the alignment status through near field communication. Since information about the vehicle size, floor height, and the arrangement of the receiver and transmitter can be immediately confirmed using RFID and NFC, the alignment ratio can be determined at a relatively low cost.

[0051] As another example, the alignment status of the transmitter (100) and the receiver (200) can be confirmed using a magnetic sensor, radar sensor, or the like, such as a hall sensor or fluxgate sensor.

[0052] Another example is the use of a vehicle's wheels to determine positional alignment. For example, the space formed by the lines connecting the front wheels, the lines connecting the front and rear wheels, and the lines connecting the rear wheels can be used to indirectly determine the receiver's position. This information can then be used to determine alignment with the transmitter.

[0053] In the wireless charging method for an electric vehicle according to the present invention, the determination of the alignment ratio can be made using various techniques mentioned above, but is not limited thereto.

[0054] In the next step, it is determined whether the alignment ratio is greater than or equal to the reference ratio (A%) (S315). Here, the reference ratio may be a critical ratio for coil to coil, but is not limited thereto. In addition, the reference ratio may be substantially set to 75%, but is not limited thereto. If the alignment ratio is less than the reference ratio (A%) (S315-NO), the power transmission efficiency of wireless charging is too low, which is not desirable. Therefore, the receiver is realigned (S320), and the alignment ratio of the transmitter and receiver is measured again (S310). At this time, in the step of realigning the receiver (S320), as mentioned above, the current alignment status of the receiver and transmitter may be visually or audibly displayed, and the driver may be prompted to realign the vehicle. In another embodiment, the alignment status of the receiver and the transmitter may be changed by adjusting the position of the transmitter. At this time, a physical control device for adjusting the position of the transmitter may be further provided. Meanwhile, if the alignment ratio is less than the reference ratio (A%), the alignment ratio of the transmitter and receiver may be re-measured at a preset cycle.

[0055] If the alignment ratio is greater than or equal to the reference ratio (A%) (S315-YES), the foreign matter detection mode is entered (S325). The wireless charging method for an electric vehicle according to the present invention utilizes three modes: a foreign matter detection mode, a low-speed charging mode, and a high-speed charging mode.

[0056] Foreign matter detection mode is a low-speed mode that divides the receiver / transmitter alignment ratio into multiple sections and determines the presence or absence of foreign matter based on the power loss ratio for each section. Since foreign matter detection mode enables foreign matter detection even with small power consumption, a relatively small first power can be supplied to the transmitter compared to the low-speed charging mode and high-speed charging mode described below.

[0057] The low-speed charging mode and the high-speed charging mode can be selected by the user, and in the low-speed charging mode and the high-speed charging mode, a greater power can be supplied to the transmitter than that supplied in the foreign matter detection mode. More specifically, in the low-speed charging mode, the second power supplied to the transmitter is greater than the first power, and in the high-speed charging mode, the third power supplied to the transmitter is greater than the second power.

[0058] Thereafter, the power loss ratio is measured while transmitting power from the transmitter to the receiver in the foreign substance detection mode (S330). At this time, the power loss ratio can be calculated based on the amount of power supplied to the transmitter and the amount of power received by the receiver.

[0059] More specifically, information on the amount of power received from a receiver placed in a vehicle is transmitted to a wireless charger on the transmitter side via wireless communication, and a power loss ratio can be calculated using the information on the amount of power received transmitted via wireless communication and the information on the amount of power supplied from the transmitter.

[0060] In another embodiment, information about the amount of power supplied from the transmitter may be transmitted to the vehicle via wireless communication, a power loss ratio may be calculated on the vehicle side, and the calculated power loss ratio may be transmitted to the wireless charger and used for charging control.

[0061] Thereafter, the presence or absence of a foreign substance is determined based on the alignment ratio and the power loss ratio. At this time, the alignment ratio and power loss ratio between the transmitter and receiver serve as the basis for determining the presence or absence of a foreign substance. Specifically, it is determined whether the power loss ratio is greater than or equal to a threshold value based on the alignment ratio (S335), and if the power loss ratio is less than the threshold value based on the alignment ratio, it is determined that a foreign substance is absent (S355).

[0062] That is, in the foreign matter detection mode, the presence or absence of a foreign matter is determined based on the alignment ratio section between the transmitter and receiver and the threshold value of the power transfer ratio for each alignment ratio section. The alignment ratio section and threshold value can be constructed as a look-up table (LUT).

[0063] In magnetic resonance wireless charging, inherent resonance loss may exist. However, if foreign matter is present between the resonant transmitter and receiver, it will absorb electromagnetic waves, further increasing the power loss ratio.

[0064] Therefore, the threshold value of the power loss ratio for determining the presence or absence of a foreign substance can be set based on the basic resonance loss ratio and the allowable loss ratio for the transmitter-receiver alignment ratio.

[0065] [Table 1] below provides examples of power loss ratio thresholds calculated based on the basic resonant loss ratio and the allowable loss ratio for alignment ratios divided into multiple intervals. For example, if the transmitter-receiver alignment ratio is 87%, the threshold could be 20%, considering the allowable loss ratio, the basic resonant loss ratio, and an appropriate margin of error for the alignment ratio.

[0066] If the measured power loss ratio is 15%, it can be determined that there is no foreign matter as it shows a power loss value within the appropriate tolerance, but if the measured power loss ratio is 28%, it can be determined that the foreign matter has increased the power loss, so it can be determined that there is a foreign matter between the transmitter and receiver.

[0067] Alignment ratioAllowable loss ratio(Alignment loss)Basic resonance loss ratioThresholdLess than 75%-Fixed value(e.g. 5%)-75∼80%20∼25%More than 30%80∼85%15∼20%More than 25%85∼90%10∼15%More than 20%90∼95%5∼10%More than 15%Over 95%Less than 5%10%More than 10%

[0068]

[0069] The above LUT (Look-up Table) can be transformed into various values ​​depending on the coil configuration, size, shape, distance between receiver and transmitter, transmission power, charging speed, charging environment (temperature, humidity, etc.), and various error values.

[0070] Meanwhile, the wireless charging method according to the present invention may use a preset LUT including an alignment ratio section and a threshold value for each alignment ratio section, but the loss ratio and threshold value for each alignment ratio may also be determined based on the following mathematical expression 1. However, the following [Mathematical expression 1] is merely an example and may be generated by a formula modified in various ways. For example, the constant 0.95 for determining the threshold value may be changed to another arbitrary constant, or an arbitrary variable not included in [Mathematical expression 1] may be further added.

[0071] [Mathematical Formula 1]

[0072]

[0073]

[0074] (L: loss ratio, A: alignment ratio, R: basic resonance loss ratio, T: threshold, a: constant value for each alignment ratio interval, α: constant value (e.g., 0.55))

[0075] Here, the constant value (a) for each sorting ratio section can be an integer greater than or equal to 1 used when calculating the threshold value according to the sorting ratio based on the number of rows that make up the LUT, and the constant value (α) can be a value for configuring a buffer for the threshold value for the convenience of the user, since when determining the presence of a foreign substance based on a value or ratio or higher, problems such as heat generation may be reduced when power is transmitted from the user's perspective at that value.

[0076] In this regard, the step of determining the presence or absence of a foreign substance may include a step of constructing an LUT including a threshold value for each alignment ratio section and alignment ratio section, and a step of determining that a foreign substance exists when the power loss ratio is greater than or equal to the threshold value.

[0077] That is, in the present invention, the alignment ratio is divided into multiple sections, an allowable power loss threshold is set for each section, and if the calculated power loss ratio is greater than the threshold in the corresponding alignment ratio section (S335), it is determined that a foreign substance is present (S345).

[0078] Meanwhile, considering cases where foreign substances exist temporarily or errors in calculating the power loss ratio, the determination of the presence or absence of foreign substances by comparing the power loss ratio with the threshold value can be performed repeatedly multiple times.

[0079] Although not shown in the drawing, the determination of whether the power loss ratio is greater than or equal to the threshold value is repeatedly performed, and if the number of times the power loss ratio is greater than or equal to the threshold value is less than N, it is determined that no foreign matter exists, and wireless charging can be performed by entering the low-speed or high-speed charging mode. Here, the number of determinations (N) for determining whether a foreign matter exists can be set to various values, and can be an integer greater than or equal to 2. In addition, the determination cycle for determining whether a foreign matter exists can also be set to various times.

[0080] Conversely, the judgment as to whether the power loss ratio is greater than or equal to the threshold value is repeatedly performed, and if the power loss ratio is greater than or equal to the threshold value for N or more consecutive times, it can be determined that a foreign substance is present.

[0081] Afterwards, if it is determined that a foreign substance exists (S345), the alignment ratio of the transmitter and receiver is measured again (S310), and the foreign substance detection mode is entered (S325), and a procedure for confirming the presence or absence of a foreign substance is performed. By re-measuring the alignment ratio of the transmitter and receiver, it is possible to prepare for changes in the alignment ratio that occur due to the removal of foreign substances and realignment of the vehicle, and errors in the previously measured alignment ratio can be identified once again. This can further increase the reliability of the subsequent determination of the presence or absence of a foreign substance.

[0082] Referring to FIG. 5, the steps described above with respect to FIG. 3 will be briefly described again. Power transmission is performed by a magnetic resonance method between a transmitter (100) having a transmitting coil and a receiver (200) having a receiving coil, and at this time, a power loss ratio is measured based on the amount of power supplied to the transmitting coil and the amount of power received by the receiving coil. The measured power loss ratio is compared with a threshold value for the power loss amount allowed in the alignment ratio section based on the previously calculated alignment ratio, and if the measured power loss ratio is equal to or higher than the threshold value corresponding to the alignment ratio section, it is determined that a foreign substance exists between the transmitter (100) and the receiver (200).

[0083] FIG. 6 is a wireless charging method for an electric vehicle according to the present invention, and illustrates a subsequent process of the flowchart of FIG. 3.

[0084] If the presence of a foreign substance is determined to be absent in the foreign substance detection mode, the device enters the low-speed or high-speed charging mode (S360). The low-speed or high-speed charging mode is performed when there is no foreign substance between the transmitter and receiver, allowing for safe wireless charging. The charging speed in the high-speed charging mode may be faster than that in the low-speed charging mode. The charging speed can be controlled differently in various ways. For example, the charging speed can be differentiated by varying the amount of power supplied to the transmitter.

[0085] Because there is a distance between the transmitter and receiver, foreign matter can enter between them even during wireless charging in either low- or fast-charging mode. This poses a risk of overheating and fire, requiring continuous monitoring for foreign matter even during charging in either low- or fast-charging mode.

[0086] Monitoring for foreign matter intrusion in low-speed or high-speed charging modes can also be performed based on the alignment ratio, power loss ratio, and preset threshold values ​​between the transmitter and receiver. That is, while performing power transfer in low-speed or high-speed charging modes, the power loss ratio is re-measured (S365), and the presence of foreign matter intrusion is determined based on the re-measured power loss ratio and alignment ratio (S370). At this time, the alignment ratio may be obtained in step S310.

[0087] However, in other embodiments, the alignment ratio may be re-obtained by re-measuring the alignment ratio of the transmitter and receiver. The threshold values ​​for the alignment ratio interval between the transmitter and the receiver and the power transfer ratio for each of the alignment ratio intervals may be the same as those used in the foreign matter detection mode. However, in other embodiments, since the amount of power used in the low-speed or high-speed charging mode is large, the allowable loss ratio and / or the basic resonant loss ratio may be different, and accordingly, the alignment ratio interval and the threshold values ​​may be set differently.

[0088] If the power loss ratio is less than the threshold value according to the alignment ratio (S370-NO), it is determined that no foreign matter has penetrated and the low-speed or high-speed charging mode is continued (S375).

[0089] If the power loss ratio is higher than the threshold value according to the alignment ratio (S370-YES), it is determined that foreign matter has penetrated (S380), and the subsequent steps can be performed.

[0090] Meanwhile, although not illustrated in FIG. 6, in cases where a foreign substance has temporarily penetrated, the presence or absence of a foreign substance may be determined to have penetrated only if the comparison between the power loss ratio and the threshold value is repeated multiple times, taking into account cases where the foreign substance has temporarily penetrated. That is, the determination as to whether the power loss ratio is greater than or equal to the threshold value may be repeated multiple times, and if the number of times the power loss ratio is greater than or equal to the threshold value is less than N, it may be determined that the foreign substance has not penetrated, and the low-speed or high-speed charging mode may continue (S375). Conversely, if the number of times the power loss ratio is greater than or equal to the threshold value continues N or more, it may be determined that the foreign substance has penetrated. Here, the number of times (N) of determinations for determining the presence or absence of a foreign substance may be set to various values, and may be an integer greater than or equal to 1. That is, since the low-speed or high-speed charging mode has a large power, even a temporary foreign substance may cause heat generation in some cases, so N may be set to 1 to ensure safety. In addition, the determination cycle for determining the presence or absence of a foreign substance may be set to various times.

[0091] FIG. 7 is a wireless charging method for an electric vehicle according to the present invention, and illustrates a subsequent process of the flowchart of FIG. 6.

[0092] If it is determined that foreign matter has penetrated in low-speed or high-speed charging mode, charging can be controlled in the manner described below.

[0093] First, as illustrated in (a) of Fig. 7, if it is determined that a foreign substance has penetrated in either low-speed or high-speed charging mode, the heat generation amount is measured (S390). The heat generation amount can be acquired by a temperature sensor provided on at least one of the transmitter and receiver. The temperature sensor may be implemented as a contact sensor such as a thermocouple, or as a non-contact sensor such as an infrared thermometer.

[0094] If the obtained calorific value is greater than or equal to the reference calorific value (H) (S390-YES), the charging mode in the low-speed or high-speed charging mode can be controlled to be switched to another mode (e.g., charging with a preset minimum power, etc.) (S391) or switched to the low-speed charging mode in order to prevent the risk of fire in advance.

[0095] Similarly, if the heat generation exceeds the reference heat generation (H2) while charging in low-speed charging mode, the charging mode can be switched to another charging mode (such as charging at a preset minimum power). Furthermore, if the heat generation exceeds the preset maximum heat generation, it can be determined to be an emergency and charging can be controlled to stop.

[0096] In addition, as illustrated in (b) of Fig. 7, if it is determined that a foreign substance has penetrated in the low-speed or high-speed charging mode, the low-speed or high-speed charging mode can be switched to another mode (e.g., charging at a preset minimum power) (S395). Then, the foreign substance detection mode is restarted (S396), the presence of the foreign substance is determined again, and if it is determined that the foreign substance has been removed, charging is executed.

[0097] Figure 8 is a flowchart of a wireless charging method for an electric vehicle according to another embodiment of the present invention.

[0098] First, it is determined whether a receiver is detected in standby mode (S400 and S405). If the receiver is not detected (S405-NO), the system continuously monitors whether a receiver is detected in standby mode (S400). If the receiver is detected (S405-YES), the alignment ratio between the transmitter and receiver is measured (S410). The hardware and software methods for measuring the alignment ratio between the transmitter and receiver are the same as those described above, so a duplicate explanation will be omitted.

[0099] Once the alignment ratio is measured, it is determined whether it is greater than or equal to the reference ratio (A%) (S415). If the alignment ratio is less than the reference ratio (A%) (S415-NO), the power transmission efficiency of wireless charging is too low, which is not desirable. Therefore, the receiver is realigned (S420), and the alignment ratios of the transmitter and receiver are measured again (S410). At this time, in the step of realigning the receiver (S420), as mentioned above, the current alignment status of the receiver and transmitter can be visually or audibly displayed, and the driver can be prompted to realign the vehicle.

[0100] In another embodiment, the alignment between the transmitter and receiver can be changed by adjusting the position of the transmitter. In this case, a physical control device for adjusting the position of the transmitter may be additionally provided. Meanwhile, if the alignment ratio is below the reference ratio (A%), the alignment ratio between the transmitter and receiver may be re-measured at preset intervals.

[0101] If the alignment ratio is greater than or equal to the reference ratio (A%) (S415-YES), the foreign substance detection mode is entered (S425). Then, the power loss ratio is measured while transmitting power from the transmitter to the receiver in the foreign substance detection mode (S430). At this time, the method for calculating the power loss ratio is as described above. If the alignment ratio and the power loss ratio are calculated, the presence or absence of a foreign substance is determined based on this. Specifically, it is determined whether the power loss ratio is greater than or equal to the threshold value according to the alignment ratio (S435), and if the power loss ratio is less than the threshold value according to the alignment ratio, it is determined that a foreign substance is absent (S455).

[0102] That is, in the foreign matter detection mode, the presence or absence of a foreign matter is determined based on the alignment ratio section between the transmitter and receiver and the threshold value of the power transfer ratio for each alignment ratio section. The alignment ratio section and threshold value can be constructed as a look-up table (LUT).

[0103] The threshold value of the power loss ratio for determining the presence or absence of a foreign substance can be set based on the basic resonance loss ratio and the allowable loss ratio for the transmitter-receiver alignment ratio. In the present invention, the alignment ratio is divided into multiple sections, and an allowable power loss threshold value is set for each section. If the calculated power loss ratio is greater than or equal to the threshold value in the corresponding alignment ratio section (S435-YES), it is determined that a foreign substance is present and an alarm can be sent (S445).

[0104] Meanwhile, considering the temporary presence of foreign substances or errors in calculating the power loss ratio, the determination of the presence of foreign substances by comparing the power loss ratio with a threshold value may be repeated multiple times, and only when the determination continues for a predetermined number of times or more, the presence of foreign substances may be determined.

[0105] Although not illustrated in Fig. 8, the determination of whether the power loss ratio is greater than or equal to the threshold value is performed repeatedly multiple times, and if the number of times the power loss ratio is greater than or equal to the threshold value is less than N times, it is determined that no foreign matter exists, and wireless charging can be performed by entering low-speed or high-speed charging mode. After entering low-speed or high-speed charging mode, operation can be performed in the same manner as described with respect to Figs. 6 and 7.

[0106] Here, the number of judgments (N) for determining the presence of a foreign substance can be set to various values ​​and can be an integer greater than or equal to 2. In addition, the judgment cycle for determining the presence of a foreign substance can also be set to various times.

[0107] Conversely, the judgment as to whether the power loss ratio is greater than or equal to the threshold value may be performed repeatedly multiple times, and only when the power loss ratio is greater than or equal to the threshold value for N or more consecutive times, it may be determined that a foreign substance exists and an alarm may be sent to the user (S445).

[0108] Alarms can be transmitted audibly or visually. For example, a beep or voice guidance alert can be sent to indicate the presence of a foreign object. The audible alarm can be output through speakers installed in the charging station or speakers within the vehicle. In some cases, an alarm control signal can be transmitted to the user's smartphone, and an audible alarm can be output through the smartphone's speaker.

[0109] In other embodiments, images and / or real-time video of the vehicle's alignment, underbody, and surroundings may be transmitted as an alarm. The transmitted images and / or video may be displayed on a display installed at the charging station or on a display inside the vehicle. In some cases, an alarm control signal may be transmitted to the user's smartphone, and the corresponding images and / or video may be displayed on the smartphone's screen.

[0110] After the alarm is sent, the alignment ratio of the transmitter and receiver is measured again (S410), and the foreign substance detection mode is entered (S425), and the presence or absence of a foreign substance is confirmed. By re-measuring the alignment ratio of the transmitter and receiver, changes in the alignment ratio that occur due to foreign substance removal and vehicle realignment can be prepared for, and errors in the previously measured alignment ratio can be identified once again. This further increases the reliability of subsequent foreign substance presence determinations.

[0111] Figure 9 is a flowchart of a wireless charging method for an electric vehicle according to another embodiment of the present invention.

[0112] First, it is determined whether a receiver is detected in standby mode (S500 and S505). If the receiver is not detected (S505-NO), the system continuously monitors whether a receiver is detected in standby mode (S500). If the receiver is detected (S505-YES), the alignment ratio between the transmitter and receiver is measured (S510). The hardware and software methods for measuring the alignment ratio between the transmitter and receiver are the same as those described above, so a duplicate explanation will be omitted.

[0113] When the alignment ratio is measured, it is determined whether it is greater than or equal to the reference ratio (A%) (S515). If the alignment ratio is less than the reference ratio (A%) (S515-NO), the receiver is realigned (S520), and the alignment ratios of the transmitter and receiver are measured again (S510). At this time, in the step of realigning the receiver (S520), as mentioned above, the current alignment status of the receiver and transmitter can be visually or audibly displayed, and the driver can be prompted to realign the vehicle.

[0114] In another embodiment, the alignment between the transmitter and receiver can be changed by adjusting the position of the transmitter. In this case, a physical control device for adjusting the position of the transmitter may be additionally provided. Meanwhile, if the alignment ratio is below the reference ratio (A%), the alignment ratio between the transmitter and receiver may be re-measured at preset intervals.

[0115] If the alignment ratio is greater than or equal to the reference ratio (A%) (S515-YES), the foreign matter detection mode is entered (S525). Then, in the foreign matter detection mode, power is transmitted from the transmitter to the receiver, and the power loss ratio is measured (S530). At this time, the method for calculating the power loss ratio is as explained above. Once the alignment ratio and power loss ratio are calculated, the presence or absence of a foreign matter is determined based on them.

[0116] In this embodiment, the presence or absence of a foreign substance is determined using first to third threshold values. The first threshold value may be a threshold value related to a power loss ratio, the second threshold value may be a threshold value related to a Q value, and the third threshold value may be a threshold value related to a Frequency value. In another embodiment, the presence or absence of a foreign substance may be determined by comparing with two or more of the three threshold values, or the presence or absence of a foreign substance may be determined by comparing with one of the three threshold values.

[0117] Specifically, it is determined whether the power loss ratio is greater than or equal to the first threshold value according to the alignment ratio (S535). That is, in the foreign matter detection mode, the presence or absence of a foreign matter is determined based on the alignment ratio section between the transmitter and receiver and the threshold value of the power transfer ratio for each alignment ratio section.

[0118] If the power loss ratio is greater than or equal to the first threshold value according to the alignment ratio (S535-YES), it is determined that a foreign substance exists and an alarm can be transmitted (S560). In this embodiment, taking into account the temporary presence of a foreign substance or an error in calculating the power loss ratio, the determination of whether the power loss ratio is greater than or equal to the first threshold value is repeatedly performed, and only if it continues for N or more times, it is determined that a foreign substance exists and an alarm can be transmitted (S560). The alarm transmission method is as described above.

[0119] If the power loss ratio is less than the first threshold value (S535-NO), the process moves to the next step. If the embodiment is such that the determination of whether the power loss ratio is greater than or equal to the first threshold value is repeated N times and the presence of a foreign substance is determined only if the determination continues for N or more times, the process can move to the next step even if the number of times the power loss ratio is greater than or equal to the first threshold value is less than N.

[0120] In the next step, the Q value is measured, and the measured Q value is compared with a second threshold value according to the alignment ratio (S545). Here, the Q value may refer to a reference quality factor value. The coil provided in the wireless power system may have a decrease in inductance and / or a series resistance component within the coil due to environmental changes, which may result in a decrease in the quality factor value. Therefore, by measuring the Q value during wireless charging of a vehicle and then determining the presence or absence of a foreign substance using a second threshold value based on the pre-measured Q value in a state where no foreign substance is placed in the vehicle charging area, the accuracy and reliability of foreign substance detection can be improved.

[0121] If the Q value is greater than or equal to the second threshold value (S545-YES), it is determined that a foreign substance exists and an alarm can be sent out (S560). In this embodiment, taking into account errors in calculating the Q value, etc., the determination of whether the Q value is greater than or equal to the second threshold value is repeatedly performed, and only if this continues for M or more times, it is determined that a foreign substance exists and an alarm can be sent out (S560).

[0122] At this time, a second threshold value for comparison with the Q value can be constructed as a look-up table (LUT). The second threshold value included in the LUT can be set in various ways based on the allowable Q value according to the receiver-transmitter alignment interval, etc.

[0123] If the Q value is less than the second threshold value according to the sorting ratio (S545-NO), proceed to the next step. If the determination of whether the Q value is greater than or equal to the second threshold value is repeatedly performed and the presence of a foreign substance is determined only if it continues for more than M times, then proceed to the next step even if the number of times the Q value is greater than or equal to the second threshold value is less than M times.

[0124] In the next step, a third threshold value is compared based on the Frequency value and the sorting ratio (S555). The Frequency value may refer to a reference peak frequency value corresponding to the wireless power receiver.

[0125] The frequency at which the quality factor value changes the most depending on the presence or absence of foreign matter is the reference peak frequency. That is, the coil of a wireless power transmission system may experience a decrease in inductance and / or series resistance within the coil due to environmental changes, which may change (shift) the coil's resonant frequency. In other words, the quality factor peak frequency, which is the frequency at which the maximum quality factor value is measured within the operating frequency band, may shift.

[0126] Therefore, by measuring the reference peak frequency during vehicle wireless charging and then determining the presence or absence of a foreign substance using a third threshold value set based on the reference peak frequency value, the foreign substance detection capability can be further improved.

[0127] If the Frequency value is greater than or equal to the third threshold value (S555-YES), it is determined that a foreign substance exists and an alarm is sent out (S560). In this embodiment as well, considering errors in calculating the Frequency value, etc., the determination as to whether the Frequency value is greater than or equal to the third threshold value is repeatedly performed, and only if the Frequency value is greater than or equal to the third threshold value K or more times, it is determined that a foreign substance exists and an alarm can be sent out (S560).

[0128] At this time, a third threshold value for comparison with the frequency value can be constructed as a look-up table (LUT). The third threshold value included in the LUT can be set based on the allowable frequency value according to the receiver-transmitter alignment interval.

[0129] If the Frequency value is less than the third threshold value according to the sorting ratio (S555-NO), it is determined that a foreign substance is absent (S570), and the process can proceed to step P1 of Fig. 6. If the process is an embodiment in which the process repeatedly determines whether the Frequency value is greater than or equal to the third threshold value, and determines that a foreign substance is present only if it continues for K or more times, the process can proceed to step P1 of Fig. 6 even if the number of times in which the Frequency value is greater than or equal to the third threshold value is less than K.

[0130] In the above description, N, M, and K are integers greater than or equal to 2, and can be set to various values ​​by the user. In addition, the comparison cycle can also be set to various times.

[0131] The wireless charging method for a vehicle according to the present invention can be performed by a wireless charging system for a vehicle, a device, or a CPU, controller, etc. included therein. Meanwhile, the present invention can be implemented as a computer program. That is, the computer program according to the present invention can be stored in a recording medium to execute the wireless charging method for a vehicle according to the present invention on a computer. In another embodiment, the wireless charging method for a vehicle according to the present invention can be implemented in the form of program commands that can be executed by various computer means and recorded on a computer-readable medium. The computer-readable recording medium can include program commands, data files, data structures, etc., singly or in combination.

Claims

When a receiver is detected, a step of measuring the alignment ratio of the transmitter and receiver; A step of entering foreign substance detection mode when the above alignment ratio is greater than or equal to the standard ratio; A step of measuring a power loss ratio while performing power transmission in the above foreign substance detection mode; A step of determining the presence or absence of a foreign substance based on the above alignment ratio and the above power loss ratio; and a step of entering a low-speed or high-speed charging mode when it is determined that the above foreign substance is absent; How to wirelessly charge an electric vehicle. In the first paragraph, The step of determining the presence or absence of the above foreign substance is: The presence or absence of the foreign substance is determined based on the alignment ratio section between the transmitter and the receiver and the threshold value of the power transmission ratio for each of the alignment ratio sections. How to wirelessly charge an electric vehicle. In the second paragraph, A step of constructing a LUT (Look-up Table) including the above sorting ratio range and the above threshold value; and A step of determining that the foreign substance is present when the power loss ratio is greater than or equal to the threshold value; further comprising; How to wirelessly charge an electric vehicle. In the second paragraph, The above threshold value is set based on the allowable loss ratio and basic resonance loss ratio in each of the above alignment ratio sections. How to wirelessly charge an electric vehicle. In the second paragraph, The step of determining that the above foreign substance exists is: The judgment as to whether the above power loss ratio is greater than or equal to the above threshold is performed repeatedly multiple times, If the above power loss ratio exceeds the above threshold value for N or more consecutive times, it is determined that the foreign substance is present. How to wirelessly charge an electric vehicle. In the first paragraph, A step of re-measuring the power loss ratio while performing power transmission in the above low-speed or high-speed charging mode; and A step of determining whether a foreign substance has penetrated based on the re-measured power loss ratio and the alignment ratio; further comprising; How to wirelessly charge an electric vehicle. In paragraph 6, A step of measuring the amount of heat generated in the low-speed or high-speed charging mode when it is determined that the foreign substance has penetrated in the low-speed or high-speed charging mode; and If the calorific value is greater than or equal to the reference calorific value, a step of stopping charging in the low-speed or high-speed charging mode is further included. How to wirelessly charge an electric vehicle. In paragraph 6, A step of stopping the low-speed or high-speed charging mode when it is determined that the foreign substance has penetrated in the low-speed or high-speed charging mode; and Further comprising a step of re-entering the foreign substance detection mode; How to wirelessly charge an electric vehicle. In the first paragraph, The amount of power supplied to the transmitter in the foreign substance detection mode is less than the amount of power supplied to the transmitter in the low-speed or high-speed charging mode. How to wirelessly charge an electric vehicle. In paragraph 9, The amount of power supplied to the transmitter in the above low-speed charging mode is: Less than the amount of power supplied to the transmitter in the above fast charging mode, How to wirelessly charge an electric vehicle. In the first paragraph, If it is determined that the foreign substance is present in the above foreign substance detection mode, Repeatedly measuring the power loss ratio and determining the presence or absence of the foreign substance at preset intervals until the foreign substance is removed. How to wirelessly charge an electric vehicle. In the first paragraph, The transmitting coil included in the transmitter and the receiving coil included in the receiver have the same resonant frequency. How to wirelessly charge an electric vehicle. In the first paragraph, further comprising a step of detecting the receiver in standby mode; How to wirelessly charge an electric vehicle. In the first paragraph, If the alignment ratio is less than the reference ratio, the step of re-measuring the alignment ratio of the transmitter and the receiver at a preset cycle is further included. How to wirelessly charge an electric vehicle.

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