Method for avoiding the magnetic core ferrite of the transmitting end of a wireless charging system from entering deep saturation

Abstract

The application provides a method for avoiding the magnetic core ferrite of a transmitting end of a wireless charging system from entering deep saturation, comprising a coupling mechanism transmitting end, which comprises a back plate, a magnetic core arranged on the middle area of the back plate, a coil arranged on the magnetic core, and a plurality of ferrites arranged on the magnetic core; when the magnetic flux is certain, the cross-sectional area through which the magnetic flux passes between the ferrites is controlled to increase so that the magnetic induction intensity on each ferrite is less than the saturation magnetic induction intensity of the ferrite, which can not only solve the problem of abnormal arrangement of the ferrites caused by insufficient process, but also avoid the ferrite from entering deep saturation, so that the whole coupling system operates in a good magnetic field environment, which is beneficial to the performance of the wireless charging system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of wireless charging technology for electric vehicles, and particularly relates to a method for avoiding the magnetic core ferrite of the transmitting end of a wireless charging system from entering deep saturation. BACKGROUND

[0002] Due to energy shortage, environmental pollution and other reasons, electrification of the transportation system has become a trend. In the railway system, electric locomotives have been developed for many years. Trains run on fixed tracks and easily obtain power from the conductor rail by using the pantograph slider.

[0003] However, for electric vehicles (EVs), the high degree of flexibility makes it difficult to obtain power in a similar way. If the battery is out of power, the electric vehicle cannot be immediately ready like a gasoline car. In order to overcome this problem, the owner needs to find any possible opportunity to charge the battery. People may forget to plug in and thus cannot travel; ground charging wires can be a tripping hazard; leaks from cracked old cables, especially in cold areas, can pose additional hazards to homeowners. In addition, people have to charge the electric car in the face of bad weather outdoors. This has brought a lot of trouble to people's lives, and the birth of wireless charging hopes to free people from the troubles of electric cars and truly become the master of electric cars.

[0004] By wirelessly transmitting energy to electric vehicles, electric car charging becomes very simple and convenient. For a fixed WPT system, the driver only needs to park and leave. For a dynamic WPT system, this means that the electric vehicle can be powered while driving; the electric vehicle can run continuously. In addition, compared with wired charging of electric vehicles, the battery capacity of wireless charging of electric vehicles can be reduced by more than 20%.

[0005] Automobile wireless charging generally adopts magnetic resonance coupling type, and the basic principle is that two objects with the same resonance frequency can achieve high energy exchange between them. The component that realizes this energy exchange is called a coupling mechanism.

[0006] The coupling mechanism is composed of a transmitting end and a receiving end. The overall structure size of the transmitting end is limited, the arrangement of each plate is compact, and the heat source is large, so it is difficult to effectively export heat, which eventually causes the overall temperature of the transmitting end to be too high. The transmitting end loss (heat source) mainly includes coil copper loss, ferrite iron loss, and eddy current loss of metal shielding components.

[0007] Iron loss accounts for a large part of the entire transmitting end loss, and the reasonable design of ferrite can effectively reduce the ferrite loss. However, due to the influence of the ferrite manufacturing and arrangement process, the ferrite often has an abnormal arrangement phenomenon. In the actual operation process of the wireless charging system, the abnormal arrangement of the ferrite will cause the ferrite to enter a deep saturation state, thereby causing a relatively large loss of the ferrite in the local area, and also increasing the eddy current loss of part of the metal parts, ultimately causing a local hot spot of the coupling mechanism and raising the overall temperature.

[0008] The deep saturation of ferrite refers to the magnetic induction intensity B (T) on the ferrite reaching the saturation value of the ferrite. As shown in Figure 1 The BH curve (magnetic characteristic curve) of the ferrite adopted is shown, the vertical coordinate is B, and the horizontal coordinate is H. Bs is the saturation value of the material. When B >= Bs, the magnetic induction intensity B no longer increases with the increase of H, that is, the magnetic permeability is 0. The electromagnetic performance of the saturated ferrite will deteriorate sharply, causing a series of adverse consequences.

[0009] In actual production, the most common and most likely to occur abnormal arrangement of ferrite is shown in FIG. 2. The excessive roughness of the surface of the ferrite around will cause incomplete contact between the ferrites. FIG. 2 (a) is a case where the contact area of the ferrite is 50%, and FIG. 2 (b) is a case where the contact area of the ferrite is 10%. At the same time, due to the influence of the ferrite arrangement process, it is difficult to keep the ferrites completely horizontal and vertical, and there is an angle and inclination phenomenon, as shown in FIG. 2 (c). It is calculated by a finite element simulation software that the core loss only exists in the three abnormal states, and the core loss is 8% larger than that of the ideal arrangement. This is only three abnormal arrangements, and there are many abnormal arrangements in the real situation. The loss increase caused by abnormal arrangement is extremely large and cannot be ignored.

[0010] Excessive temperature will cause some components to work abnormally, and even cause the product to completely fail, causing great economic loss and safety accidents. In addition, the deep saturation of the ferrite will further reduce the quality factor and the self-inductance of the coil, which is not conducive to the performance of the entire wireless charging system. SUMMARY

[0011] In order to solve the above technical problems, the method for avoiding the ferrite core of the transmitting end of the wireless charging system from entering deep saturation provided by the application can not only solve the problem of abnormal arrangement of the ferrite caused by process deficiency, but also avoid the problem of the ferrite entering deep saturation, so that the entire coupling system operates in a good magnetic field environment, which is beneficial to the performance of the wireless charging system.

[0012] In order to achieve the above purpose, the technical scheme of the application is as follows:

[0013] The application provides a method for avoiding deep saturation of a magnetic core ferrite of a transmitting end of a wireless charging system, comprising: a coupling mechanism transmitting end, the coupling mechanism transmitting end comprising: a back plate, a magnetic core arranged on a middle area of the back plate, a coil arranged on the magnetic core, and the magnetic core being composed of multiple ferrites; when the magnetic flux is constant, the cross-sectional area through which the magnetic flux passes between the ferrites is increased, and the difference between the cross-sectional areas through which the magnetic flux passes between the ferrites approaches 0, so that the magnetic induction intensity on each ferrite is less than the saturation magnetic induction intensity on the ferrite.

[0014] The method for avoiding deep saturation of the magnetic core ferrite of the transmitting end of the wireless charging system can not only solve the problem of abnormal arrangement of the ferrites caused by insufficient process, but also avoid deep saturation of the ferrites, so that the entire coupling system operates in a good magnetic field environment, which is beneficial to the performance of the wireless charging system.

[0015] As a preferred technical solution, the calculation formula for increasing the cross-sectional area through which the magnetic flux passes between the ferrites and making the difference between the cross-sectional areas through which the magnetic flux passes between the ferrites approach 0 is as follows:

[0016] B = φ / S

[0017] In the formula, φ is the magnetic flux, S is the cross-sectional area through which the magnetic flux passes, and B is the magnetic induction intensity on the ferrite.

[0018] As a preferred technical solution, the method for increasing the cross-sectional area through which the magnetic flux passes between the ferrites and making the difference between the cross-sectional areas through which the magnetic flux passes between the ferrites approach 0 comprises the following steps:

[0019] S1: initially determining the possible range of the interval value d between every two adjacent ferrites;

[0020] S2: further determining the minimum value of the interval value between every two adjacent ferrites as d min ;

[0021] S3: further determining the maximum value of the interval value between every two adjacent ferrites as d max ;

[0022] S4: determining the value of d: determining the range of d as d min ~ d max , and calculating the value of d by the formula d = (d min +d max ) / 2;

[0023] S5: arranging the uniform insulating material with the thickness of the value of d between every two ferrites at equal intervals to form a normally arranged magnetic core.

[0024] As a preferred technical solution, the step S1 preliminarily determines the possible range of the size of the interval value d between every two adjacent ferrite, including the following steps: establishing an electromagnetic simulation of the transmitting end of the coupling mechanism, setting different ferrite interval values d, analyzing the self-inductance, mutual inductance and coupling coefficient of the transmitting end of the coupling mechanism under different ferrite interval values d, and preliminarily determining the possible range of the size of the interval value d between every two adjacent ferrite.

[0025] As a preferred technical solution, the regulation increases the cross-sectional area through which the magnetic flux between each ferrite passes, and makes the difference between the cross-sectional areas through which the magnetic flux between each ferrite passes approach 0, and further includes the following steps: S6 establishing a temperature rise experiment of the transmitting end of the coupling mechanism under the normally arranged magnetic core with equal intervals and the transmitting end of the coupling mechanism under the abnormally arranged magnetic core with unequal intervals, arranging the temperature rise data, drawing a temperature rise curve, and comparing the temperature rise data according to the drawn temperature rise curve.

[0026] As a preferred technical solution, the d min is 0.3 mm.

[0027] As a preferred technical solution, the d max is 0.7 mm.

[0028] The method for avoiding the ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application has the following beneficial effects:

[0029] 1) The method for avoiding the ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application can effectively prevent the problems of high loss, high temperature and decline of the performance of the overall coupling mechanism caused by deep saturation of the ferrite after the magnetic core is optimized by using the method;

[0030] 2) The method for avoiding the ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application can effectively solve the problem of abnormal arrangement of the ferrite caused by process deficiency, and effectively regulate and increase the area (that is, the cross-sectional area S through which the magnetic flux passes) facing each ferrite to be large enough and have a small size difference, so that the magnetic induction intensity B value of each ferrite is less than the saturation magnetic induction intensity Bs of the ferrite, so that the transmitting end of the overall coupling mechanism operates in a good magnetic field environment, and effectively prevents the ferrite from entering deep saturation;

[0031] 3) The method for avoiding the ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application uses the uniform d value thickness of the insulating material derived and calculated to separate every two adjacent ferrites, so that the adverse contact between the ferrites caused by abnormal arrangement can be avoided, and the ferrite can be effectively prevented from entering deep saturation. BRIEF DESCRIPTION OF DRAWINGS

[0032] Figure 1 A schematic diagram of the BH curve (magnetic characteristic curve) of the ferrite used as background art;

[0033] Fig. 2 is a schematic diagram of the most common and most likely abnormal arrangement of the ferrite (Fig. 2(a) is the case of 50% ferrite contact area, Fig. 2(b) is the case of 10% ferrite contact area. Fig. 2(c) is the case of angle and inclination due to the influence of the ferrite arrangement process, it is difficult to keep the ferrite completely horizontal and vertical) proposed as background art;

[0034] Figure 3 A schematic diagram of the transmitting end of the coupling mechanism of the wireless charging system proposed by the present application;

[0035] Figure 4 A schematic diagram of the transmitting end of the coupling mechanism of the wireless charging system proposed by the present application; Figure 3 A partial enlarged view of the magnetic core in the transmitting end of the coupling mechanism of the wireless charging system proposed by the present application;

[0036] Figure 5 A schematic diagram of the temperature rise curve of the transmitting end of the coupling mechanism under the normally arranged magnetic core with equal intervals and the transmitting end of the coupling mechanism under the abnormally arranged magnetic core with unequal intervals proposed by the present application (the dotted line is the temperature rise curve of the transmitting end of the coupling mechanism under the normally arranged magnetic core with equal intervals, and the solid line is the temperature rise curve of the transmitting end of the coupling mechanism under the abnormally arranged magnetic core with unequal intervals);

[0037] Fig. 6 is a schematic diagram of the distribution of the magnetic induction intensity B of the ferrite (Fig. 6(a) is the distribution of the magnetic induction intensity B of the ferrite before the method of the present application is used, and Fig. 6(b) is the distribution of the magnetic induction intensity B after the method of the present application is used);

[0038] Wherein, 1-back plate; 2-magnetic core; 3-coil; 4-ferrite; 5-uniform insulating material with a thickness of d value. DETAILED DESCRIPTION

[0039] The preferred embodiments of the present application will be described in detail below with reference to the accompanying drawings.

[0040] It can be understood that the present application is achieved by some embodiments in order to achieve the purpose of the present application, and the method for avoiding the ferrite of the magnetic core of the transmitting end of the wireless charging system from entering deep saturation provided by the present application comprises: the transmitting end of the coupling mechanism (such as Figures 3-4The coupling mechanism emission end comprises a back plate 1, the material of the back plate 1 is preferably aluminum, a magnetic core 2 is arranged on the middle area of the back plate 1, a coil 3 is arranged on the magnetic core 2, the magnetic core 2 is composed of multiple ferrite blocks 4, when the magnetic flux is certain, the cross-sectional area through which the magnetic flux passes between the ferrite blocks 4 is controlled to increase, and the difference between the cross-sectional areas through which the magnetic flux passes between the ferrite blocks 4 tends to be 0, so that the magnetic induction intensity on each ferrite block 4 is less than the saturation magnetic induction intensity on the ferrite block 4; the cross-sectional area through which the magnetic flux passes between the ferrite blocks 4 is controlled to increase, and the difference between the cross-sectional areas through which the magnetic flux passes between the ferrite blocks 4 tends to be 0 according to the following calculation formula:

[0041] B = φ / S

[0042] In the formula, φ is the magnetic flux, S is the cross-sectional area through which the magnetic flux passes, and B is the magnetic induction intensity on the ferrite;

[0043] Controlling the cross-sectional area through which the magnetic flux passes between the ferrite blocks to increase, and the difference between the cross-sectional areas through which the magnetic flux passes between the ferrite blocks tends to be 0, comprises the following steps:

[0044] S1, preliminarily determine the possible range of the interval value d (mm) between each two adjacent ferrite blocks 4, establish an electromagnetic simulation of the coupling mechanism emission end, set different ferrite block interval values d, analyze the self-inductance, mutual inductance and coupling coefficient of the coupling mechanism emission end under different ferrite block interval values d, and preliminarily determine the possible range of the interval value d (mm) between each two adjacent ferrite blocks 4;

[0045] S2, further determine the minimum value of the interval value d between each two adjacent ferrite blocks 4 as d min , d min should not be too small (the ideal state d = 0 also meets the requirements), because of the process limitation, the interval value d (mm) between each two adjacent ferrite blocks 4 is too small, and the purpose of avoiding excessive saturation of the ferrite cannot be achieved, generally, the interval value d (mm) between each two adjacent ferrite blocks 4 is greater than or equal to 0.3 mm;

[0046] S3, further determine the maximum value of the interval value d between each two adjacent ferrite blocks 4 as d max , d max should not be too large, a larger interval value d (mm) will reduce the ability of the ferrite to bind the magnetic field, and will significantly increase the magnetic flux leakage of the ferrite, thereby increasing the eddy current loss of the back plate 1; whether there is enough space to accommodate d max , the interval value d (mm) between each two adjacent ferrite blocks is less than or equal to 0.7 mm;

[0047] S4, determine the value of d: determine the range of d as d min ~ d max, the d min is 0.3mm, the d max is 0.7mm; the d value is calculated by the formula d=(d min +d max ) / 2, and the d value is calculated;

[0048] S5, the uniform insulation material 5 with a thickness of d value is arranged between every two ferrite 4 at equal intervals to form the equally spaced normal arrangement of the magnetic core 2;

[0049] S6, the temperature rise experiment is conducted on the coupling mechanism transmitting end under the equally spaced normal arrangement of the magnetic core and the coupling mechanism transmitting end under the non-equally spaced abnormal arrangement of the magnetic core, the temperature rise data is sorted, the temperature rise curve (as shown in Figure 5 ) is drawn, the temperature rise data is compared according to the drawn temperature rise curve; the temperature of the coupling mechanism transmitting end under the equally spaced normal arrangement of the magnetic core is reduced by about 15 DEG C; thus, the optimization of the magnetic core ferrite of the coupling mechanism transmitting end is completed, and the deep saturation of the ferrite is avoided.

[0050] The method for avoiding the deep saturation of the magnetic core ferrite of the transmitting end of the wireless charging system provided by the application can not only solve the problem of abnormal arrangement of the ferrite caused by insufficient process, but also avoid the deep saturation of the ferrite, so that the whole coupling system runs in a good magnetic field environment, which is beneficial to the performance of the wireless charging system.

[0051] The method for avoiding the deep saturation of the magnetic core ferrite of the transmitting end of the wireless charging system provided by the application comprises a coupling mechanism transmitting end (as shown in Figures 3-4 ), which comprises a back plate 1, the material of the back plate 1 is preferably aluminum, a magnetic core 2 is arranged on the middle area of the back plate 1, a coil 3 is arranged on the magnetic core 2, the magnetic core 2 is composed of multiple ferrite 4, when the magnetic flux is constant, the cross-sectional area through which the magnetic flux passes between the multiple ferrite 4 is controlled to be increased, and the difference between the cross-sectional areas through which the magnetic flux passes between the multiple ferrite 4 tends to be 0, so that the magnetic induction intensity on each ferrite 4 is less than the saturation magnetic induction intensity on the ferrite 4; the cross-sectional area through which the magnetic flux passes between the multiple ferrite 4 is controlled to be increased, and the difference between the cross-sectional areas through which the magnetic flux passes between the multiple ferrite 4 tends to be 0, according to the following formula:

[0052] B=φ / S

[0053] In the formula, φ is the magnetic flux, S is the cross-sectional area through which the magnetic flux passes, and B is the magnetic induction intensity on the ferrite 4; the cross-sectional area through which the magnetic flux passes between the multiple ferrite 4 is controlled to be increased, and the difference between the cross-sectional areas through which the magnetic flux passes between the multiple ferrite 4 tends to be 0, comprising the following steps:

[0054] S1, the interval value d (mm) between every two adjacent ferrite 4 is preliminarily determined in the range of [0, 1];

[0055] S2, the minimum interval value d between every two adjacent ferrite 4 is further determined min = 0.3 mm;

[0056] S3, the maximum interval value d between every two adjacent ferrite 4 is further determined max = 0.7 mm;

[0057] S4, the value of d is calculated by the formula d = (d min +d max ) / 2, and the value of d is 0.5 mm after calculation;

[0058] S5, the uniform insulation material with a thickness of 0.5 mm is arranged between every two ferrite 4 at equal intervals to form the magnet core 2 arranged at equal intervals;

[0059] S6, the temperature rise experiment is conducted on the coupling mechanism transmitting end under the magnet core arranged at equal intervals and the coupling mechanism transmitting end under the magnet core arranged at abnormal intervals, the temperature rise data is sorted, the temperature rise curve (as shown in Figure 5 ) is drawn, and the temperature rise data is compared according to the drawn temperature rise curve; from Figure 5 , it can be observed that the temperature of the coupling mechanism transmitting end under the magnet core arranged at equal intervals is reduced by 16℃; thus, the optimization of the magnet core ferrite 4 of the coupling mechanism transmitting end is completed, and the ferrite 4 from entering deep saturation is avoided;

[0060] The magnetic fields before and after the method is adopted are simulated and analyzed, the magnetic induction intensity B of the abnormal arrangement before the method is adopted is 0.7798 T, and the magnetic induction intensity B after the method is adopted is 0.2586 T, as shown in FIG. 6. The general ferrite saturation magnetic induction intensity Bs is 0.55 T, the magnetic induction intensity B of the abnormal arrangement is 0.7798 T, which has reached deep saturation, and the magnetic induction intensity B after the method is adopted is 0.2586 T, which is far from saturation, so it can be seen that the method provided in the application can effectively avoid the problem that the magnet core ferrite of the transmitting end of the wireless charging system enters deep saturation.

[0061] The method for avoiding the magnet core ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application has the following beneficial effects:

[0062] 1) The method for avoiding the magnet core ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application can effectively prevent the problems of high loss, high temperature and the decline of the overall coupling mechanism performance caused by deep saturation of the ferrite after the magnet core optimized by the method;

[0063] 2) The method for avoiding the magnetic core ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application can effectively solve the problem of abnormal arrangement of ferrite caused by insufficient process, effectively regulate and control the area (that is, the cross-sectional area S through by the magnetic flux) of each ferrite to be large enough and have small size difference, ensure that the B value of the magnetic induction intensity of each ferrite is less than the saturation magnetic induction intensity Bs of the ferrite, so that the transmitting end of the entire coupling mechanism operates in a good magnetic field environment, effectively preventing the ferrite from entering deep saturation;

[0064] 3) The method for avoiding the magnetic core ferrite of the transmitting end of the wireless charging system from entering deep saturation provided by the application uses the insulating material with the uniform d value thickness calculated to separate each two adjacent ferrites, which can avoid the bad contact caused by abnormal arrangement of the ferrites, effectively preventing the ferrite from entering deep saturation.

[0065] It can be understood that the application is described through some embodiments, and those skilled in the art know that various changes or equivalent replacements can be made to the features and embodiments without departing from the spirit and scope of the application. In addition, the features and embodiments can be modified to adapt to specific conditions and materials under the guidance of the application without departing from the spirit and scope of the application. Therefore, the application is not limited by the specific embodiments disclosed herein, and all changes or equivalent replacements falling within the scope of the claims of the application belong to the scope of protection of the application.

Claims

1. A method for preventing the ferrite core of the transmitter in a wireless charging system from entering deep saturation, characterized in that, The application relates to a coupling mechanism transmitting end, which comprises a back plate provided with a magnetic core in the middle area, and the magnetic core is provided with a coil and is composed of multiple ferrite blocks; when the magnetic flux is constant, the cross-sectional area through which the magnetic flux passes among the ferrite blocks is increased, and the difference between the cross-sectional areas through which the magnetic flux passes among the ferrite blocks approaches 0, so that the magnetic induction intensity on each ferrite block is less than the saturation magnetic induction intensity on the ferrite. The method for increasing the cross-sectional area through which the magnetic flux passes among the ferrite blocks and making the difference between the cross-sectional areas through which the magnetic flux passes among the ferrite blocks approach 0 comprises the following steps: S1, preliminarily determining the possible range of the interval value d between every two adjacent ferrite blocks; The method comprises the following steps: establishing electromagnetic simulation of the coupling mechanism transmitting end, setting different ferrite interval values d, analyzing the self-induction, mutual induction and coupling coefficient of the coupling mechanism transmitting end under different ferrite interval values d, and preliminarily determining the possible range of the interval value d between every two adjacent ferrite blocks. The calculation formula for increasing the cross-sectional area through which the magnetic flux passes among the ferrite blocks and making the difference between the cross-sectional areas through which the magnetic flux passes among the ferrite blocks approach 0 is as follows:

2. The method of claim 1, wherein, B = phi / S In the formula, phi is the magnetic flux, S is the cross-sectional area through which the magnetic flux passes, and B is the magnetic induction intensity on the ferrite. The method for increasing the cross-sectional area through which the magnetic flux passes among the ferrite blocks and making the difference between the cross-sectional areas through which the magnetic flux passes among the ferrite blocks approach 0 further comprises the following steps:

3. The method of claim 1, wherein, S5, arranging the uniform insulating material with the thickness of the interval value d between every two ferrite blocks at equal intervals to form the normally arranged magnetic core with equal intervals. S2 further defines the minimum value of the interval between every two adjacent ferrite blocks as d min ; S3 further defines the maximum value of the spacing between every two adjacent ferrite pieces as d max ; S4 determine the value of d: the range of d is d min ~ d max , the value of d is calculated by the formula d = (d min +d max ) / 2, and the value of d is calculated. The method for increasing the cross-sectional area through which the magnetic flux passes among the ferrite blocks and making the difference between the cross-sectional areas through which the magnetic flux passes among the ferrite blocks approach 0 further comprises the following steps: S6, establishing the coupling mechanism transmitting end under the normally arranged magnetic core with equal intervals and the coupling mechanism transmitting end under the abnormally arranged magnetic core with unequal intervals to carry out the temperature rise experiment, arranging the temperature rise data, drawing the temperature rise curve, and comparing the temperature rise data according to the drawn temperature rise curve.

4. The method of avoiding deep saturation of the magnetic core ferrite of a transmitting end of a wireless charging system of claim 3, wherein, ​ 5. The method of avoiding deep saturation of the magnetic core ferrite of a transmitting end of a wireless charging system of claim 3, wherein, The d min is 0.3 mm.

6. The method of avoiding deep saturation of the magnetic core ferrite of a transmitting end of a wireless charging system of claim 3, wherein, The d max is 0.7 mm.

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