KR102418335B1 - Foreign object detection apparatus for wireless power transmission - Google Patents

Abstract

A foreign material sensor device for wireless power transmission according to an embodiment includes a feeding coil unit that transmits electrical energy so that the current collecting coil unit can receive electrical energy by a magnetic induction method, and conductive foreign substances that may exist in the vicinity of the feeding coil unit and a sensor coil part whose inductance is changed by the .

Description

Foreign matter sensor device for wireless power transmission

The present invention relates to a foreign material sensor device for wireless power transmission that detects a foreign object in the vicinity when wireless power is transmitted.

Although the use of electric vehicles as an eco-friendly means of transportation is increasing recently, there is a limitation in that frequent charging is required due to the low energy density of the battery.

The charging method of an electric vehicle may be largely divided into slow charging and fast charging.

In the case of slow charging, there is an advantage that it can be charged using a household power source, but there is a disadvantage that it requires a charging time of 3 hours or more.

In contrast, fast charging has the advantage that it requires a charging time of less than 30 minutes, but has a disadvantage in that a high-power wireless charging device using high voltage and current is required.

In addition, the conventional charging method includes a method of supplying electric energy by inserting a plug, which may cause inconvenience in that it requires a manipulation for charging from a driver.

In response to these shortcomings, the frequent charging operation required by the user can be eliminated by applying the wireless charging technology. That is, when a wireless power transmission device based on high power is used, the time required for charging can be reduced and manipulation required by the driver for charging can be minimized.

The wireless charging technology for charging electric vehicles mainly uses induction power transmission, a wireless power transmission technology based on magnetic induction coupling, which operates on the principle that electric energy is induced through magnetic field coupling without direct connection of conductors.

In the induction power transmission technology, as the strength of the magnetic field, which is the medium of electrical energy transmission, increases, the size of the electrical energy that can be transmitted increases.

When a conductor having conductivity exists in the vicinity of the wireless charging operation, a magnetic field generated from the wireless charging system is induced in the conductive material, and at this time, a reverse magnetic field according to an eddy current is generated on the surface of the conductor. The strength of the eddy current varies depending on the strength of the induced magnetic field, and when a high strength magnetic field is induced, the eddy current effect also increases proportionally, and as the eddy current effect increases, heat also increases.

If the strength of the magnetic field is very large, the object may ignite as when a metallic material is put in a microwave oven, and in this case, the risk of fire due to the conductive material increases.

When the magnetic field generated in the wireless charging system is induced in the conductor, the conductor operates as a load to the wireless charging system, and as a result, power fluctuation occurs during the charging operation, so foreign substances can be detected.

However, when there is a misalignment between the coils during wireless charging, the power state is different from that of normal operation. In addition, most of the wireless charging operation operates on the battery as a charging target, and the battery is supplied with different power according to the state of charge (SOC).

As a result, it is difficult to determine whether the occurrence of the power fluctuation is due to a foreign substance or whether it is caused by the battery charge state and left-right mismatch only with the power fluctuation of the wireless charging system. .

Korean Patent Publication No. 10-2020-0032469 (published on March 26, 2020)

According to an embodiment of the present invention, there is provided a foreign material sensor device for wireless power transmission that detects with high accuracy that a conductive foreign material is present in the vicinity of a power supply coil.

However, the problems to be solved of the present invention are not limited to those mentioned above, and other problems to be solved that are not mentioned can be clearly understood by those of ordinary skill in the art to which the present invention belongs from the following description. will be.

A foreign object sensor device for wireless power transmission according to an aspect includes a power supply coil unit for transmitting electrical energy so that a current collecting coil unit can receive electrical energy by a magnetic induction method, and a conductivity that may exist in the vicinity of the power supply coil unit The sensor coil unit includes a sensor coil in which inductance is changed by the foreign material, and a determination unit configured to determine whether the conductive foreign material is present based on the change in inductance of the sensor coil unit.

According to one embodiment, it is possible to detect the presence of a conductive foreign material in the vicinity of the feeding coil with high accuracy regardless of the battery charge state of the wireless power receiving side corresponding to the wireless power transmission and irrespective of misalignment between the coils. can

1 is a perspective view of a partial configuration of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
2 is a top view of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
3 is a front view of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
4 is an equivalent circuit diagram of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
5 is a perspective view of a sensor coil unit of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
6 is a diagram illustrating a turn order of a horizontal coil and a vertical coil of a sensor coil unit of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
7 to 12 are diagrams illustrating the effect of the magnetic field of the sensor coil part and the reverse magnetic field of the conductive foreign material in the foreign material sensor device for wireless power transmission according to an embodiment of the present invention.
13 and 14 are diagrams assuming a situation in which mismatch occurs in the foreign material sensor device for wireless power transmission according to an embodiment of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described below in detail in conjunction with the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, but may be implemented in various different forms, and only these embodiments allow the disclosure of the present invention to be complete, and common knowledge in the art to which the present invention pertains It is provided to fully inform those who have the scope of the invention, and the present invention is only defined by the scope of the claims.

Terms used in this specification will be briefly described, and the present invention will be described in detail.

The terms used in the present invention have been selected as currently widely used general terms as possible while considering the functions in the present invention, but these may vary depending on the intention or precedent of a person skilled in the art, the emergence of new technology, and the like. In addition, in a specific case, there is a term arbitrarily selected by the applicant, and in this case, the meaning will be described in detail in the description of the corresponding invention. Therefore, the term used in the present invention should be defined based on the meaning of the term and the overall content of the present invention, rather than the name of a simple term.

When a part 'includes' a certain component throughout the specification, this means that other components may be further included, rather than excluding other components, unless otherwise stated.

In addition, the term 'unit' used in the specification means software or a hardware component such as an FPGA or ASIC, and 'unit' performs certain roles. However, 'part' is not limited to software or hardware. The 'unit' may be configured to reside on an addressable storage medium or it may be configured to refresh one or more processors. Thus, as an example, 'part' refers to components such as software components, object-oriented software components, class components and task components, processes, functions, properties, procedures, subroutines, segments of program code, drivers, firmware, microcode, circuitry, data, databases, data structures, tables, arrays and variables. Functions provided within components and 'units' may be combined into a smaller number of components and 'units' or further divided into additional components and 'units'.

Also, in an embodiment of the present invention, when it is said that a part is connected to another part, this includes not only direct connection but also indirect connection through another medium. In addition, the meaning that a certain part includes a certain component means that other components may be further included, rather than excluding other components, unless specifically stated to the contrary.

Hereinafter, with reference to the accompanying drawings, the embodiments of the present invention will be described in detail so that those of ordinary skill in the art can easily implement them. In describing embodiments of the present invention with reference to the drawings, if it is determined that a detailed description of a well-known function or configuration may unnecessarily obscure the gist of the present invention, the detailed description thereof will be omitted. In addition, the terms to be described later are terms defined in consideration of functions in an embodiment of the present invention, which may vary according to intentions or customs of users and operators. Therefore, the definition should be made based on the content throughout this specification.

1 is a perspective view of a part of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention, and FIG. 2 is a top view of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention, FIG. is a front view of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention, FIG. 4 is an equivalent circuit diagram of a foreign material sensor device for wireless power transmission according to an embodiment of the present invention, and FIG. 5 is an embodiment of the present invention It is a perspective view of the sensor coil unit of the foreign material sensor device for wireless power transmission according to the present invention.

1 to 5, the foreign material sensor device for wireless power transmission according to an embodiment of the present invention is a power supply nose that transmits electrical energy so that the current collecting coil unit 10 can receive electrical energy by magnetic induction. part 110 .

The collecting coil unit 10 may be installed in a wireless power receiving device capable of receiving electric energy (eg, a wireless charging device of an electric vehicle, etc.). The current collecting coil unit 10 may include a current collecting coil 11 and a current collecting ferrite 12 . The current collecting ferrite 12 serves to increase the inductance by increasing the magnetic flux density of the magnetic field by the current collecting coil 11 . In FIG. 1 , the current collector ferrite 12 is transparently illustrated for better understanding.

The current collecting ferrite 12 of the current collecting coil unit 10 has a polygonal outer edge when viewed from the current collecting coil unit 110 side. For example, as shown in FIG. 1 , the current collecting ferrite 12 may have a rectangular outer edge.

The current collecting coil 11 of the current collecting coil unit 10 has a polygonal outer rim and an inner rim, respectively, when viewed from the power feeding coil unit 110 side. For example, as shown in FIG. 1 , the current collecting coil 11 may have a rectangular outer rim and an inner rim, respectively.

In addition, the feeding coil unit 110 may include a feeding coil 111 and a feeding ferrite 112 . The feeding ferrite 112 serves to increase the inductance by increasing the magnetic flux density of the magnetic field by the feeding coil 111 .

The feeding ferrite 112 of the power feeding coil unit 110 has a polygonal outer edge when viewed from the current collecting coil unit 10 side. For example, as shown in FIG. 1 , the fed ferrite 112 may have a rectangular outer rim.

The feeding coil 111 of the power feeding coil unit 110 has a polygonal outer rim and an inner rim, respectively, when viewed from the current collecting coil unit 10 side. For example, as shown in FIG. 1 , the feeding coil 111 may have a rectangular outer rim and an inner rim, respectively.

In addition, the foreign material sensor device for wireless power transmission further includes a sensor coil unit 120 whose inductance is changed by a conductive foreign material that may exist in the vicinity of the power supply coil unit 110 . The sensor coil unit 120 is disposed to be spaced apart from at least one of the outer edges of the plurality of directions of the polygonal shape of the power feeding coil unit 110 . For example, the sensor coil unit 120 may be disposed on the outer edges of the power feeding coil unit 110 in four directions due to the rectangular shape. The sensor coil unit 120 may include a horizontal coil 121 and a vertical coil 122 that are orthogonal to each other. The horizontal coil 121 and the vertical coil 122 may have polygonal inner and outer edges, respectively. For example, as shown in FIG. 5 , the horizontal coil 121 and the vertical coil 122 have a rectangular inner rim and an outer rim, respectively, and share one of the four sides of the quadrangle with each other. can The turn order of the horizontal coil 121 and the vertical coil 122 may be an order of turning three sides that are not shared with each other before one side shared with each other among the four sides of the quadrangle. 6 is a diagram illustrating a turn order of the horizontal coil 121 and the vertical coil 122 . In this case, mutual interference does not occur between the vertically configured part and the horizontally configured part in terms of the direction of the current. When the horizontal coil 121 is turned before the vertical coil 122 , it may be turned in the direction of the arrow illustrated in FIG. 6 . Alternatively, the vertical coil 122 may be turned before the horizontal coil 121 .

In addition, the foreign material sensor device for wireless power transmission further includes a determination unit (not shown) that determines whether there is a conductive foreign material in the vicinity of the power supply coil unit 110 based on a change in inductance of the sensor coil unit 120 . include For example, the determination unit may include computing means such as a microprocessor. 1 to 3 mainly show the structural form of the foreign material sensor device for wireless power transmission, so the illustration of the determination unit, which can be said to be an electrical and electronic component, is omitted.

In the following description, a case in which the sensor coil unit 120 is disposed on the outer edges of the power feeding coil unit 110 in four directions by a rectangular shape will be described as an example. For example, a case in which the sensor coil unit 120 is disposed around the east, around the west, around the south, and around the north of the feeding coil unit 110 will be described. do.

The foreign material sensor device for wireless power transmission as described above may be represented by an equivalent circuit diagram as shown in FIG. 4 . The electrical characteristic values written together in the equivalent circuit diagram of FIG. 4 are as follows.

은 전원이며, 급전 코일(111)에 공급되는 전기적 에너지 발생원이다.

is a power source, and is a source of electrical energy supplied to the power supply coil 111 .

는 전류를 통해 자기장을 형성하여 자기 유도 결합에 의해 전기에너지를 전송하기 위한 급전 코일(111)이다.

is a feeding coil 111 for transmitting electric energy by magnetic inductive coupling by forming a magnetic field through an electric current.

는 급전 코일(111)에서 발생한 자기장에 의해 자기 유도 결합 회로를 형성하여 전기에너지를 수신하기 위한 집전 코일(11)이다.

is a current collecting coil 11 for receiving electrical energy by forming a magnetic inductively coupled circuit by the magnetic field generated in the feeding coil 111 .

는 급전 코일(111)의 인덕턴스에 대응하는 용량성 리액턴스를 보상하여 특정 주파수에서 공진(Resonance)이 발생하도록 적용하는 커패시터이다.

is a capacitor applied to generate resonance at a specific frequency by compensating for capacitive reactance corresponding to the inductance of the feeding coil 111 .

는 집전 코일(11)의 인덕턴스에 대응하는 용량성 리액턴스를 보상하여 특정 주파수에서 공진이 발생하도록 적용하는 커패시터이다.

is a capacitor applied to generate resonance at a specific frequency by compensating for capacitive reactance corresponding to the inductance of the current collecting coil 11 .

,

,

,

는 전도성 이물질을 감지하기 위해 급전 코일(111)을 중심으로 동쪽(East), 서쪽(West), 남쪽(South), 북쪽(North)에 설치되는 센서 코일(121, 122)이다.

,

,

,

are sensor coils 121 and 122 installed in the east, west, south, and north of the feeding coil 111 to detect the conductive foreign material.

는 전력 전송이 이루어지는 급전 코일(111)과 집전 코일(11) 간의 상호 인덕턴스이다.

is the mutual inductance between the power supply coil 111 and the current collector coil 11 through which power transmission is performed.

,

,

,

는 자기장을 발생시키는 급전 코일(111)과 센서 코일(121, 122) 간의 상호 인덕턴스이다.

,

,

,

is the mutual inductance between the feeding coil 111 and the sensor coils 121 and 122 for generating a magnetic field.

,

,

,

는 급전 코일(111)로부터 자기장을 전달받는 집전 코일과 센서 코일(121, 122) 간의 상호 인덕턴스이다.

,

,

,

is the mutual inductance between the current collecting coil and the sensor coils 121 and 122 receiving the magnetic field from the feeding coil 111 .

주변에 전도성 이물질이 위치할 경우,

는 와전류 영향을 받게 되며, 이에 따라 코일의 인덕턴스가 변화하게 된다. 이 때 동쪽의 센서 코일(121, 122)에 발생하게 되는 유도 전압은 [식 1]과 같이 정의되며, 이 때 상호 인덕턴스는 [식 2]와 같이 정의된다.In the sensor coil unit 120 disposed in all directions of the feeding coil unit 110 , when a conductive foreign material exists around the feeding coil unit 110 , a voltage fluctuation occurs according to an inductance change, and based on the voltage fluctuation occurrence Thus, the determination unit (not shown) may determine whether foreign matter is present. For example, a sensor coil installed on the east side

If there is a conductive foreign substance in the vicinity,

is affected by the eddy current, and accordingly the inductance of the coil changes. At this time, the induced voltage generated in the sensor coils 121 and 122 on the east side is defined as [Equation 1], and in this case, the mutual inductance is defined as [Equation 2].

(식 1)

(Equation 1)

(식 2)

(Equation 2)

는 각주파수(

, f=주파수)를 의미하고, k는 두 코일 간 결합 계수(Coupling coefficient)를 의미한다. 즉, 두 코일간 이격거리 변화가 없더라도 와전류 영향에 의해

가 감소하게 되며, 이는 상호 인덕턴스의 변화를 발생시켜 결과적으로 유도전압이 감소하게 되는 것을 의미한다.For [Equation 1] and [Equation 2],

is the angular frequency (

, f = frequency), and k means a coupling coefficient between two coils. That is, even if there is no change in the separation distance between the two coils, the

is decreased, which means that the mutual inductance changes and consequently the induced voltage decreases.

Now, a principle of detecting whether a conductive foreign material is present in the vicinity of the power supply coil unit 110 through the sensor coil unit 120 will be described.

의 위상차를 가지도록 발생한다. 이때, 발생하게 되는 역자기장이 코일에 쇄교하지 못하면 코일의 인덕턴스 변화가 발생하지 않는다.When a magnetic field is incident on a conductor, the reverse magnetic field generated is relative to the incident magnetic field.

occurs to have a phase difference of . At this time, if the generated reverse magnetic field does not link to the coil, the inductance of the coil does not change.

7 to 12 show a horizontal type coil 121 of the sensor coil unit 120 when a vertical conductive foreign material 30 is disposed around the power supply coil unit 110 or a horizontal conductive foreign material 40 is disposed around the power supply coil unit 110 . It is a view showing the effect of the reverse magnetic field (30a, 40a) on the magnetic field (121a) and the magnetic field (122a) of the vertical coil (122).

In order for the horizontal coil 121 or the vertical coil 122 to be affected by the reverse magnetic fields 30a and 40a generated from the conductive foreign substances 30 and 40, the magnetic fields 121a and 122a of the sensor coil unit 120) And the reverse magnetic field (30a, 40a) should be generated in the direction facing each other. The magnetic field 122a of the vertical coil 122 reacts to the vertical conductive foreign material 30 , and the horizontal coil 121 has a significant response to the horizontal conductive foreign material 40 . That is, when the magnetic fields 121a and 122a and the reverse magnetic fields 30a and 40a are generated in opposite directions, the reverse magnetic fields 30a and 40a link the inside of the horizontal coil 121 or the vertical coil 122. , As a result, the inductance of the horizontal coil 121 or the vertical coil 122 is changed. In other words, the vertical coil 122 is difficult to detect the horizontal conductive foreign material 40 , and the horizontal coil 121 is difficult to detect the vertical conductive foreign material 30 . Therefore, the sensor coil unit 120 is designed so that the horizontal coil 121 and the vertical coil 122 include all of the sensor coil unit 120 to enable sensing regardless of the shape of the conductive foreign material. That is, when the vertical conductive foreign material 30 is disposed in the vicinity, it can be detected through the vertical coil 122, and when the horizontal conductive foreign material 40 is disposed in the vicinity, the horizontal coil 121 is used. can be detected through If the conductive foreign material is configured in a three-dimensional shape, both the horizontal coil 121 and the vertical coil 122 react, so the sensing performance is also increased. The radii of the horizontal coil 121 and the vertical coil 122 are related to the sensing distances for the conductive foreign substances 30 and 40, and as the radius of the horizontal coil 121 and the vertical coil 122 increases, the more It is easy to detect foreign objects from a distance. The radius of the horizontal coil 121 and the vertical coil 122 may be determined by considering an increase in the size of the foreign material sensor device for wireless power transmission and a foreign material detection distance.

Next, when misalignment between the coils occurs, the effect on the detection of foreign substances will be examined. When a mismatch occurs between the coils, a change in mutual inductance occurs, and this effect also occurs in the mutual inductance between the current collecting coil unit 10 and the sensor coil unit 120 . In this case, it may be uncertain whether the change in power generated in the sensor coil unit 120 in detecting foreign substances is caused by mismatch or foreign substances. In this case, it is possible to distinguish whether the mismatch occurs through a change in power according to a change in the coupling coefficient with the current collecting coil unit 10 in which the mismatch occurs. For example, assuming a situation in which mismatch occurs as shown in FIG. 13 , mismatch occurred only in one direction of the y-axis, and the center point of the sensor coil in four directions of the sensor coil unit 120 from the center of the current collecting coil unit 10 and It can be seen that there is a difference in the distance of This phenomenon also occurs when the mismatch of the X-Y axes as shown in FIG. 14 occurs at the same time. That is, a coupling coefficient change occurs according to a change in the separation distance between each sensor coil and the current collecting coil unit 10 , and accordingly, a change in the aspect of power generated in the sensor coil unit 120 occurs. When a mismatch occurs, the change of the coupling coefficient is different even in the same mismatch state depending on the presence or absence of foreign substances. change into rules. For example, the distance between the centers of the east sensor coil Sensor_E and the west sensor coil Sensor_W and the center of the current collecting coil unit 10 has a constant relationship and changes. In other words, when the east sensor coil and the collecting coil unit 10 come closer, the west sensor coil and the collecting coil unit 10 have a relativity that the distance is proportional to this, and accordingly, the coupling coefficient between the two coils is change in a certain relationship. This rule is equally applied to the north sensor coil (Sensor_N) and the south sensor coil (Sensor_S), and as a result, a change in the amount of power in either sensor coil is related to a change in the amount of power in the opposite coil. If a foreign material approaches in a mismatched state, a situation occurs that violates the regularity of the coupling coefficient with the opposite coil as described above, and accordingly, it is possible to detect a foreign material even in a mismatch situation.

As described so far, according to the embodiments of the present invention, the presence of conductive foreign substances in the vicinity of the power supply coil is independent of the battery charge state of the wireless power receiving side corresponding to the wireless power transmission and irrespective of the mismatch between the coils. It can be detected with high accuracy.

Combinations of each step in each flowchart attached to the present invention may be performed by computer program instructions. These computer program instructions may be embodied in a processor of a general purpose computer, special purpose computer, or other programmable data processing equipment, such that the instructions performed by the processor of the computer or other programmable data processing equipment provide the functions described in each step of the flowchart. It creates a means to do these things. These computer program instructions may also be stored in a computer-usable or computer-readable medium that may direct a computer or other programmable data processing equipment to implement a function in a particular manner, and thus the computer-usable or computer-readable medium. The instructions stored in the recording medium are also possible to produce an article of manufacture including instruction means for performing the functions described in each step of the flowchart. The computer program instructions may also be mounted on a computer or other programmable data processing equipment, such that a series of operational steps are performed on the computer or other programmable data processing equipment to create a computer-executed process to create a computer or other programmable data processing equipment. It is also possible that instructions for performing the processing equipment provide steps for performing the functions described in each step of the flowchart.

Further, each step may represent a module, segment, or portion of code comprising one or more executable instructions for executing the specified logical function(s). It should also be noted that in some alternative embodiments it is also possible for the functions recited in the steps to occur out of order. For example, it is possible that two steps shown one after another may in fact be performed substantially simultaneously, or that the steps may sometimes be performed in the reverse order according to the corresponding function.

The above description is merely illustrative of the technical spirit of the present invention, and various modifications and variations will be possible without departing from the essential characteristics of the present invention by those skilled in the art to which the present invention pertains. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical spirit of the present invention, but to explain, and the scope of the technical spirit of the present invention is not limited by these embodiments. The protection scope of the present invention should be construed by the following claims, and all technical ideas within the equivalent range should be construed as being included in the scope of the present invention.

10: current collecting coil unit 11: current collecting coil
12: current collector ferrite
110: feeding coil unit 111: feeding coil
112: fed ferrite
120: sensor coil unit 121: horizontal coil
122: vertical coil

Claims (7)

A power feeding coil unit for transmitting the electric energy so that the current collecting coil unit can receive the electric energy by a magnetic induction method;
a sensor coil unit whose inductance is changed by conductive foreign substances that may exist around the power supply coil unit;
And a determination unit for determining the presence of the conductive foreign material based on the change in the inductance of the sensor coil unit,
The power feeding coil unit has a polygonal outer edge when viewed from the current collecting coil unit side,
The sensor coil unit is disposed to be spaced apart from at least one of the outer edges in a plurality of directions by a polygon,
The sensor coil unit includes a horizontal coil and a vertical coil that are orthogonal to each other,
The horizontal coil and the vertical coil are each having a polygonal inner rim and an outer rim
Foreign matter sensor device for wireless power transmission. delete delete delete delete The method of claim 1,
The horizontal type coil and the vertical type coil have a shape each having a rectangular inner rim and an outer rim, and share one of the four sides of the rectangle with each other.
Foreign matter sensor device for wireless power transmission. 7. The method of claim 6,
The turn order of the horizontal coil and the vertical coil is to turn three sides that are not shared with each other before one side shared with each other among the four sides of the quadrangle.
Foreign matter sensor device for wireless power transmission.

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