阅读说明：本技术 用于无线电力传送的线圈设计 (Coil design for wireless power transfer ) 是由 古斯塔沃·J·梅哈斯 戚韬 于 2018-12-21 设计创作，主要内容包括：在一些实施例中,提供了发射线圈结构。根据一些实施例的用于无线发射器的线圈结构可以包括：多个线匝,所述多个线匝耦接在第一抽头和第二抽头之间,所述第一抽头耦接到最内部线匝,所述第二抽头耦接到最外部线匝；以及至少一个调节抽头,所述至少一个调节抽头耦接到发射器线圈的在所述最内部线匝和所述最外部线匝之间的至少一个线匝。发射线圈可以包括耦接到该发射线圈的第二抽头的MST线圈。在一些实施例中,所述MST线圈可以包括：布置成圆形、椭圆形、蛋形或方形中的一个的多个线匝。(In some embodiments, a transmit coil structure is provided. A coil structure for a wireless transmitter according to some embodiments may include: a plurality of turns coupled between a first tap coupled to the innermost turn and a second tap coupled to the outermost turn; and at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn. The transmit coil may include a MST coil coupled to a second tap of the transmit coil. In some embodiments, the MST coil may comprise: a plurality of turns arranged in one of a circle, an oval, an egg, or a square.)

1. A coil structure for a wireless transmitter, comprising:

a plurality of turns coupled between a first tap coupled to the innermost turn and a second tap coupled to the outermost turn; and

at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn.

2. The coil structure of claim 1, further comprising a Magnetically Safe Transfer (MST) coil coupled to the second tap.

3. The coil structure of claim 2, wherein the MST coil comprises a plurality of turns formed in a circle.

4. The coil structure of claim 2, wherein the MST coil comprises a plurality of turns formed into an ellipse.

5. The coil structure of claim 2, wherein the MST coil comprises a plurality of turns formed in an egg shape.

6. The coil structure of claim 2, wherein the MST coil comprises a plurality of turns formed in a square.

7. The coil structure of claim 2, further comprising a ferrite material.

8. A wireless power transfer system, comprising:

a controller;

a transmit coil including a plurality of turns having an innermost turn and an outermost turn, the innermost turn coupled to a first tap, the outermost turn coupled to a second tap, and at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn, the second tap coupled to a first output node of the controller and the first tap coupled to a second output node of the controller;

at least one switch controlled by the controller and coupled between the second tap and the at least one regulation tap,

wherein a transmit controller adjusts the at least one switch to control the active area of the transmit coil.

9. The transmission system of claim 8, wherein an effective area of the transmit coil is adjusted by the transmission controller to be smaller than an area of a receiver coil.

10. The transmission system of claim 8, wherein the transmit coil is configured as a magnetically safe transmission MST coil.

11. The transmission system of claim 8, wherein the plurality of turns of the transmit coil are formed on a substrate comprising ferrite.

12. The transmission system of claim 8, further comprising: a magnetically safe transmission MST coil coupled to the second tap of the transmit coil and coupled, wherein the transmission controller is further coupled to a magnetically safe transmission MST coil.

13. The transmission system of claim 12, wherein the MST coil comprises a plurality of turns arranged in a circle.

14. The transmission system of claim 12, wherein the MST coil comprises a plurality of turns arranged in an ellipse.

15. The transmission system of claim 12, wherein the MST coil comprises a plurality of turns arranged in an egg shape.

16. A method of wirelessly transferring power, comprising:

driving a transmit coil, the transmit coil including a plurality of turns having an innermost turn and an outermost turn, the innermost turn coupled to a first tap, the outermost turn coupled to a second tap, and at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn; and

adjusting an area of the transmit coil using the at least one adjustment tap according to an area of a receiver coil.

Technical Field

Embodiments of the present invention relate to wireless charger systems, and in particular to coil designs for use in wireless power transfer systems.

Background

Mobile devices, such as smart phones, tablet computers, wearable devices, and other devices, increasingly use wireless charging systems. Typically, wireless power transfer involves a transmitter driving a transmit coil and a receiver with a receiver coil placed near the transmit coil. The receiver coil receives the wireless power generated by the transmit coil and uses the received power to drive a load, such as to power a battery charger.

Generally, a wireless power system includes: a transmitter coil driven to produce a time-varying magnetic field; and a receiver coil positioned relative to the transmitter coil to receive power transmitted in the time-varying magnetic field. Such coils may also be used for or in conjunction with Magnetic Safe Transfer (MST) of data between a transmitter and a receiver.

There are currently a number of different standards for wireless power transfer. More common Wireless Power transmission standards include the Wireless charging Alliance (Alliance for Wireless Power) (A4WP) standard and the Wireless charging Alliance (Qi) standard. According to the wireless charging alliance Qi specifications, a single device is charged at the resonant frequency of the receiver coil circuit using a resonant inductive coupling system. In the Qi standard, the receiving device coil is placed close to the transmitting coil, whereas in the A4WP standard, the receiving device coil may be placed close to the transmitting coil, possibly together with other receiving coils belonging to other charging devices.

Generally, a wireless power system includes: a transmitter coil driven to produce a time-varying magnetic field; and a receiver coil, which may be part of a device such as a cellular telephone, PDA, computer or other device, positioned relative to the transmitter coil to receive the power transmitted in the time-varying magnetic field. The design of the coil may affect the efficiency of the wireless power transfer.

In most systems, the transmitter includes a transmit coil that efficiently transmits wireless power, while the receiver includes a receiver coil that efficiently receives wireless power. The transmitter coil and the receiver coil have different configurations for performing their functions.

Therefore, there is a need to develop better coil technology for wireless power transfer.

Disclosure of Invention

In some embodiments, a transmit coil structure is provided. A coil structure for a wireless transmitter according to some embodiments may include: a plurality of turns coupled between a first tap coupled to the innermost turn and a second tap coupled to the outermost turn; and at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn. The wireless power transmission system may include: a controller; a transmit coil including a plurality of turns having an innermost turn and an outermost turn, the innermost turn coupled to a first tap, the outermost turn coupled to a second tap, and at least one adjustment tap coupled to at least one turn of the transmitter coil between the innermost turn and the outermost turn, the second tap coupled to a first output node of the controller and the first tap coupled to a second output node of the controller; and at least one switch controlled by the controller and coupled between the second tap and the at least one adjustment tap, wherein the transmission controller adjusts the at least one switch to control the active area of the transmit coil. The transmit coil may include a MST coil coupled to a second tap of the transmit coil. In some embodiments, the MST coil may comprise: a plurality of turns arranged in one of a circle, an oval, an egg, or a square.

These and other embodiments are further discussed below with respect to the following figures.

Drawings

Fig. 1 shows the magnetic field around the transmitting coil and the receiving coil when the area of the transmitting coil is larger than the area of the receiving coil.

Fig. 2 shows the magnetic field around the transmitting coil and the receiving coil when the area of the transmitting coil is smaller than the area of the receiving coil.

Fig. 3A illustrates a transmit coil that may adjust area according to some embodiments.

Fig. 3B shows a transmit coil combined with a MST coil, in accordance with some embodiments.

Fig. 4 shows the transmit coil of fig. 3B coupled to a transmitter controller.

Fig. 5A and 5B illustrate magnetic safe transfer performance around an example MST coil, according to some embodiments.

Fig. 6A and 6B illustrate magnetic safe transmission performance around another example of a coil according to some embodiments.

Fig. 7A and 7B illustrate magnetic safe transmission performance around another example of a coil according to some embodiments.

Fig. 8A, 8B, and 8C illustrate magnetic field performance of various coil designs according to some embodiments.

Fig. 9A, 9B, 9C, and 9D illustrate some coil design shapes that may be used in embodiments of the present invention.

These and other aspects of the invention are discussed further below.

Detailed Description

In the following description, specific details are set forth describing some embodiments of the invention. It will be apparent, however, to one skilled in the art, that some embodiments may be practiced without some or all of these specific details. The specific embodiments disclosed herein are intended to be illustrative rather than restrictive. Those skilled in the art may implement other elements that, although not specifically described herein, are within the scope and spirit of the present disclosure.

The description illustrating the inventive aspects and embodiments should not be construed as limiting the invention, which is defined by the claims. Various changes may be made without departing from the spirit and scope of the specification and claims. In some instances, well-known structures and techniques have not been shown or described in detail to avoid obscuring the invention.

A transmitter coil according to some embodiments may include: a plurality of turns coupled between the first lead and the second lead; and at least one tap coupled to a turn of the transmitter coil at a point between the first lead and the second lead. In some embodiments, a Magnetically Safe Transfer (MST) coil may be coupled to an outer turn of the plurality of turns.

Fig. 1 shows the magnetic field strength between a transmit coil 106 and a receive coil 104 located a distance apart in a wireless power transfer structure 100. As shown in fig. 1, the transmit coil 106 is mounted on the substrate 108, and the receive coil 104 is mounted on the substrate 102, each of which may use a ferromagnetic material. In the configuration 100, the area of the receive coil 104 is smaller than the area of the transmit coil 106. Although any diameter and number of turns may be used, in many cases, the transmit coil 106 may have a diameter on the order of 10 cm. The ferrite material is located at the emission center.

As shown in the magnetic field diagram of fig. 1, the magnetic field strength around structure 100 shows a strong magnetic field in region 118, region 122, and region 114. The high magnetic field strength 122 is coupled through the coil 104. As shown in FIG. 1, with a current of about 3A passing through transmit coil 106, the magnetic field in region 116, region 118, and region 122 is about 1E-2 Tesla and the magnetic field strength in region 114 is about 3E-2 Tesla. The magnetic field strength in region 110 is about 1E-3 tesla, while the magnetic field strength in region 112 is about 1E-5 tesla. In such systems, there may be a significant amount of friendly metal heating (friendly metal heating) resulting in a reduction in the efficiency of the power delivery system and possibly causing heating damage in the receiving device. Friendly metal is present in the receiving device near region 118, region 120, region 110, and region 112.

In systems where the area of the receive coil is larger than the area of the transmit coil, the amount of heat generated will be much lower. Fig. 2 shows a receive coil 204 mounted on a substrate 202 placed a spaced distance above a transmit coil 206 mounted on a substrate 208. As shown in fig. 2, the area of the receive coil 204 is larger than the area of the transmit coil 206. As shown in fig. 2, the magnetic field is dispersed so that most of the magnetic field passes through the receiving coil. As shown in FIG. 2, region 210 has the strongest field of about 1E-2 Tesla, while region 212 is a field of about 3E-3 Tesla. The magnetic field weakens such that region 214 has a field of about 3E-4 tesla and region 216 has a field of 4E-5 tesla. Thus, as described above, most of the magnetic field is received into the region of the coil 204.

Those skilled in the art will recognize that the magnetic field strength data provided in fig. 1 and 2 are relevant and indicate one example of such coils. The actual magnetic field strength depends on the coil configuration, the coil area, the number of turns, the current through the coil, and other parameters. Providing an example of the magnetic field strength may provide a relevant indication of the performance of the coil structure.

In some embodiments, additional taps may be provided in the transmit coil to reduce the area of the transmit coil as needed. Such a transmitting coil 300 is shown in fig. 3A. As shown in fig. 3A, the transmit coil structure 300 includes a spiral winding 308, wherein a first tap 302 is coupled to an outer end of the spiral winding 308 and a second tap 306 is coupled to an inner end of the spiral winding 308. The third tap 304 may then be coupled to an intermediate point in the spiral winding 308. Typically, there may be multiple taps in the transmitter coil to further adjust the area of the transmitter coil relative to the receiver coil to reduce the amount of heat experienced during power transfer. Thus, the size of the active portion of the transmit coil structure 300 may be adjusted to the size of the receive coil placed in close proximity to the transmit coil 300 in order to reduce the heat in the resulting system.

As shown in fig. 3A, the third tap 304 may be configured to reduce the effective area of the transmit coil 300, however, it also reduces the number of transmit coil winding turns by, for example, half. The rectifier voltage V applied to the active part of the transmitting coil 300 can then be reduced_rectTo compensate. For example, if tap 304 is arranged to reduce the number of turns of coil 308 by 1/2, voltage V_rect1/2 may be reduced, which may result in a voltage drop from 8V to 4V. Increasing the rectifier voltage (e.g., from 8V to 16V) may help improve efficiency. Such a system may include a power management IC that may boost the voltage from the battery. The Vrect node of the power receiver should also be able to handle the increased voltage. Furthermore, any large residual transmitting ferrite may reduce the effect of reducing the effective area of the transmitting coil 300.

Fig. 3A shows a transmit coil 300 with one additional tap 304 coupled to the middle turn of the coil 308. In this manner, the size of the transmit coil 300 may be modified depending on conditions to provide better coupling with a corresponding receive coil. In some embodiments, more than one additional tap 304 may be added to provide additional flexibility in the size of the active portion of the transmit coil 300. Further, as shown in fig. 3B, the transmitting coil 300 may be combined with another coil.

Fig. 3B shows a coil structure 312 formed by the combination of the transmit coil 308 shown in fig. 3A and a Magnetic Secure Transaction (MST) coil 310. The combination of transmit coil 300 and MST coil 310 may be used in a system that provides MST communication. As shown in fig. 3B, the MST coil 310 is coupled to a tap (tab)302 of the transmit coil structure 300 and provides another tap 314 coupled to the coil 310. In some embodiments, portions of the coil 308 are also used in MST communication.

Fig. 4 illustrates a transmit system 400 having a control system 402 coupled to the transmit coil 300 shown in fig. 3. The control system 402 may be a singleAn IC including a switching circuit between an output AC1 and an output AC 2. The output AC1 and the output AC2 may be used for wireless transmission of power and MST communications. The switch circuit is coupled to the voltage V_rectVoltage V of_rectFrom the battery voltage V via the switch 410_batTo the control system 402. As described above, the input rectifier voltage V may be provided at any level_rectThe transmit coil 300 is coupled between the output AC1 and the output AC2, where the tap 302 and the tap 304 may be shorted by the switch 406 furthermore, the MST coil 310 may be coupled to provide communication the MST coil 310 may also be coupled between the AC1 and the AC2 to provide communication as long as the resulting resonant time constant of the MST coil and the coil 300 produced by the coil 310 is greater than the L C time of the capacitor 404 in place.

The control system 402 may include microcontroller operating firmware that may be used to control the transmit coils and process the Magnetically Safe Transfer (MST) of data. Reducing the area of the transmit coil using taps 302, 304, and 306 on the transmit coil 300 may reduce the heat from friendly metal heating. In some cases, two back-to-back MOSFETs, shown as switch 406, switch 408, and switch 410, may be used to isolate portions of the coil structure 312. Switch 406, switch 408, and switch 410 are controlled by control signals from control system 402. As shown, switch 408 and switch 410 may be controlled to switch between MST mode and transmit mode. The switch 406 is controlled to reduce or enlarge the area of the transmit coil structure 300. In some embodiments, switch 406 may represent a plurality of individual switches that adjust the size of coil 300 across a plurality of adjustment taps. A separate switch may be placed between the pairs of taps to adjust the size of the active area of the coil structure 300. Furthermore, the transmitting coil 300 may be operated at a higher switching frequency. A higher voltage system input voltage may be used for efficiency and may be adjusted as described above when adjusting the number of turns of coil 300. The control system 402 may also monitor the efficiency of the wireless transmission to adjust the area of the coil structure to be smaller than the area of a receive coil placed in the vicinity of the transmit coil structure 300.

An additional reason for varying the number of turns in the coil structure 300 is to align the geometry of the transmit coil 300 with the geometry of the corresponding receive coil. Some coils have a large OD and a large ID, and some coils have a small OD and a small ID. Changing the taps allows the control system 402 to arrange good coupling (and therefore good efficiency) for a wide range of coil sizes. Specific examples are a coil for a telephone and a coil for a watch. The phone coil tends to have an OD of 44mm and an ID of 20mm, while wearable devices generally tend to have an OD of 20mm and an ID of 14 mm. Thus, using a coil with an OD of 44mm, a tap at 20mm, and an ID of 14mm, the control system 402 is adjusted between the phone coil and the watch coil as needed.

The heat can also be reduced by a better input voltage. When the transmitter uses a voltage of 5V to 12V on the rectifier, power transfer efficiency can be improved. In some cases, the transmit controller 402 may provide a boost input. The receiver charging system should be able to accept the additional voltage generated by the transmit coil 300 operating at the higher voltage.

In some embodiments, as shown in fig. 3B, the MST coil 310 may be incorporated as one or two portions of the transmit coil 300. In this case, the efficacy of the transmitting coil 300 as a transmitting coil for wireless power transfer and a communication coil for MST communication can be tested.

Fig. 5A, 5B, 6A, 6B, 6C, and 6D illustrate MST test operations for a conventional coil design structure. The test coil designs tested in these figures are similar to the coils shown in fig. 3A and 3B, except that there are no additional taps similar to the tap 304 connected to the middle turn of the coil as present in embodiments of the invention. Fig. 5A and 5B test a conventional coil with an additional MST assembly. Fig. 6A, 6B, 6C and 6D test a conventional coil without the MST assembly. The performance of certain embodiments of the present invention is discussed below. The test is performed by measuring MST transmission failure or success using a MST receive coil positioned at a distance above the coil plane according to position in the x-y plane. In addition, performance in the y-z plane can also be tested.

FIGS. 5A and 5B show MST operation diagrams (operations)n map) and the test result, wherein the MST segment to which the transmit coil is connected is tested. Without the MST switch, the coil to be tested is connected between AC1 and AC2, as shown in fig. 4 for transmit coil 300, and functions as an MST coil. V_rectFig. 5A shows a map in an X-Y plane with the center of the receive coil positioned 2cm above the transmit coil under test and positioned at the indicated X-Y location fig. 5B shows a similar z-Y map with X set at 0cm, typically the area of the transmit coil is the X-Y plane and the distance from the transmit coil is designated the z direction fig. 5A and 5B show a range of relative positions of the receive coil with respect to the transmit coil such as coil 300 if the data can be transmitted fig. 5A shows a total of 116 total qualifiers in position for transmission of data at each position (75.8%) the qualification rate in the X-Y plane is for a total of 116 qualifiers in position (75.8%) as disclosed in us 7 application No. 16/028,207 filed in us 7, the contents of which are hereby incorporated by reference, the success rate of which is incorporated by reference, the contents of the switching application published by this application, as published in us 7, No. 2018, 16/028,207.

Fig. 6A and 6B show similar tests with the same test coil, where the associated MST coil is not used. As shown by the transmit coil 300 in fig. 4, the test coil is connected between AC1 and AC 2. In this test configuration, V_rectSet to 4V, MST baud rate set to 300 μ s the transmit coil (no MST part) has an inductance of L ═ 8.5 μ H and a resistance R ═ 0.36 ohm. coil current is held at 3a as previously described, fig. 6A shows the effect of data transmission in the x-y plane using the receive coil at a distance z of 2cm above the x-y plane of the transmit coil and positioned at the indicated x-y position fig. 6B shows the effect in the y-z plane where x is held at 0 as shown in fig. 6A the yield in the x-y plane totals 120 (78.4%), which is slightly better than the structure shown in fig. 5A and 5B.

Fig. 7A and 7B show similar tests, in which the test coil is configured as described in fig. 6A and 6B, with the current through the coil increasing. Fig. 7A shows the performance of MST data transmission in the x-y plane, where the receiver coil is positioned at a z-distance of 2cm above the x-y plane of the transmitter coil. Fig. 7B shows the performance when the receive coil is moved around on the y-z plane with x-0. As shown in fig. 7A, the yield in the x-y plane rose to a total of 129 (84.3%), and the yield improved.

Therefore, the test was performed only in the case where a wireless power coil (no MST coil) was connected between AC1 and AC2 as shown in fig. 4. V_rect4V and MST baud rate set to 300 μ s as described above, the coil has an inductance of L ═ 8.5 μ H and a resistance of 0.36 ohms the coil current is set to 3.8a as shown in fig. 7A and 7B, the increased current provides better performance of the MST of the data.

The embodiment of the present invention as shown in fig. 3A and 3B may result in higher test results. In a similar test as described above, coil 312 as described above may yield a total of 170 yields in the x-y plane when coil 308 and coil 310 are combined with switch 406 engaged as shown in FIG. 4. Using only coil 308, the yield may be 142. Further, as described above, the transmitting coil 300 may be configured to adjust the size of the active portion of the transmitting coil 300, thereby reducing heat during power transfer. The use of the transmit coil structure 312 may result in better MST performance and may improve performance by increasing the current through the transmit coil 312.

In addition to providing a transmit coil with multiple taps (e.g., transmit coil 300 as shown in fig. 3A and 3B), the shape of MST coil 310 can be adjusted to optimize MST transmission performance. Fig. 8A, 8B and 8C illustrate some of the effects of coil shape on the performance of the transmit coil in both wireless power transfer and MST data transfer.

Fig. 8A illustrates an elliptical MST coil 800 according to some embodiments of the invention that may be used as the coil 310 shown in fig. 3B. The elliptical MST coil 800 may include elliptical windings 802 formed on a substrate 804. In some embodiments, the substrate 804 may be a ferrite material. Similarly, fig. 8B shows a circular MST coil 810 that can be used as the MST coil 310 shown in fig. 3B. The circular coil 810 includes windings 812 disposed on a substrate 814. Also, the substrate 814 may be a ferrite material. In some embodiments, the circular coil 810 may represent the coil 308 when the MST coil 310 is not present in the system (e.g., MST transmission is performed by the transmit coil 308).

Figure 8C shows the magnetic field strength of the y-component of the magnetic field as a function of position at a height of 2cm above the coil being tested. In the illustration of fig. 8C, the taps of the elliptical transmitting coil 800 and the circular transmitting coil 810 use the entire coil. In fig. 8C, curve 820 shows the magnetic field strength for the y-component of the magnetic field generated by a 6 cm wide (in the y-direction) elliptical coil 800. Curve 822 shows the magnetic field strength of the y-component of the magnetic field generated by a 10cm diameter circular coil 810. The coils may be arranged to have the same coil resistance characteristics. As shown, both the WPC coil and MST coil and the WPC coil alone passed the MST test. In some embodiments, additional ferrites may be used for the elliptical coil 800. In addition, a large current may be used in the circular transmitting coil 810. Figure 824 shows a conventional WPC coil. It can be seen that the elliptical coil greatly enhances the y-component of the magnetic field above the coil area.

In some embodiments, as described above, improvements in MST can be seen using elliptical coils. Furthermore, additional ferrites may be used. It is expected that the coil resistances (DC resistance and AC resistance) match the resistance of the transmit coil 308 as shown in fig. 3B. Such an arrangement may provide better coverage of about 25%, while yield test results are much higher. Further, greater currents may be used in some embodiments. However, this approach may result in ferrite saturation, increased battery consumption, and increased controller IC size.

Fig. 9A, 9B, 9C, and 9D illustrate various shapes of coils that may be used as coils 310 in coil structure 312 according to some embodiments of the invention. Fig. 9A shows a circular coil 902. Fig. 9B shows an elliptical coil 904. Fig. 9C shows an "egg-shaped" coil 906. Fig. 9D shows a square coil 908. As discussed with respect to coil 310 of coil structure 12 shown in fig. 3B, each of coil 902, coil 904, coil 906, and coil 908 may be combined with a transmit coil 308 having multiple taps to adjust the active area of the transmit coil to reduce heat. As discussed in connection with fig. 8C, the elliptical transmitting coil 904 may result in an increase in magnetic flux along the central axis of about 25%. However, the egg-shaped transmit coil 906 may provide the maximum field at the top of the phone, which is where flux is desired for better MST transmission.

The above detailed description is provided to illustrate specific embodiments of the invention and is not intended to be limiting. Many variations and modifications are possible within the scope of the invention. The invention is set forth in the appended claims.