CN109787370B - Wireless power transmission system with positioning function - Google Patents

Abstract

A wireless power transmission system with positioning function, comprising: a power transmitting end, including a resonance transmitting circuit, the resonance transmitting circuit includes a transmitting coil; and a power receiving end, including a resonance receiving circuit, the resonance receiving circuit includes a receiving The coil is used for power induction with the sending coil to generate a resonant receiving voltage; wherein, the power transmitting end adjusts the sending current through the resonant sending circuit according to the level of the resonant receiving voltage, so that the resonant receiving voltage is maintained at a target voltage level The wireless power transmission system determines the offset distance between the power receiving end and the power transmitting end according to the adjusted transmission current through the resonant transmission circuit.

Description

Wireless power transmission system with positioning function

technical field

The present invention relates to a wireless power transmission system with positioning function and a positioning method for wireless power transmission.

Background technique

In the wireless charging system, there is an optimal relative position between the power receiving end and the power transmitting end. When the relative position of the power receiving end and the power transmitting end is in the best relative position, it can have the best power transmission efficiency, otherwise, When the power transmitting end and the power receiving end are misaligned, that is, when the current relative positions of the power receiving end and the power transmitting end are offset by a distance from the optimal relative position, the power transmission efficiency therebetween will decrease. If the transmitting current of the power transmitting end is increased to increase the received power of the power receiving end to the target voltage level, the heat generated by the power transmission of the power transmitting end will increase, and the operating temperature will also increase. If the operating temperature is too high and the protection function of the battery or electronic components is activated to reduce the transmission current of the power transmitting end, the received power of the power receiving end will decrease again, resulting in reduced power transmission efficiency. Therefore, how to detect the offset distance from the optimal relative position and provide suggestions for users to adjust the relative position or distance between the power transmitting end and the power receiving end is very important.

Referring to Figure 1, the abscissa is the offset distance between the current relative position and the optimal relative position between the power transmitting end and the power receiving end, and the abscissa to the right represents the larger the offset distance (that is, the farther from the optimal relative position). ). The ordinate is the energy loss of power transmission between the power transmitting end and the power receiving end, and the upward direction of the ordinate represents the higher the energy loss. According to the curve in the figure, it can be known that when the offset distance between the power transmitting end and the power receiving end is larger, the energy loss of the power transmission between the power transmitting end and the power receiving end is also higher.

Traditionally, the method of aligning the power transmitting end and the power receiving end, such as the technology proposed in the US patent case US20160204616, in which the power transmitting end provides a stable power, and the power receiving end judges according to the induced voltage at different relative positions. The alignment position with the highest induced voltage is an optimal relative position of the power receiving end relative to the power transmitting end. The location detection function of this case is implemented in the ping phase. When entering the power transfer phase, it is impossible to sense or indicate whether the power receiving end is in the optimal relative position.

Another conventional technique, see US 20160094043, synchronously compares the power transmission efficiency between the power transmitting end and the power receiving end. When the comparison value between the power efficiencies exceeds a threshold, it is determined that the power receiving end is located at a distance from the power transmitting end. an optimal relative position. The implementation of the location detection in this case requires that both the power transmitting end and the power receiving end are in the process of power transmission. In this way, in the ping phase or the negotiation phase, it is impossible to sense whether the power receiving end is located at this optimal relative position. In addition, since the power transmission efficiency needs to be calculated, it is necessary to sense the power transmitting end at the same time. With respect to the sending voltage, sending current, receiving voltage and receiving current of the power receiving end, the circuit design is complex and the production cost is high.

In view of this, the present invention aims at the deficiencies of the above-mentioned prior art, and proposes a wireless power transmission system and wireless power transmission that can easily and quickly find the optimal relative position in the signaling phase, the negotiation phase, or the power transmission phase. positioning method.

SUMMARY OF THE INVENTION

In one aspect, the present invention provides a wireless power transmission system, comprising: a power transmission end, including a resonance transmission circuit and a control unit, the control unit controls the resonance transmission circuit, wherein the resonance transmission circuit includes a a transmitting coil; and a power receiving end, including a resonant receiving circuit, the resonant receiving circuit including a receiving coil, for performing power induction with the transmitting coil by means of electromagnetic induction to generate a resonant receiving voltage, the power receiving end has an optimal relative position relative to the power transmitting end; wherein, when the resonant transmitting circuit and the resonant receiving circuit perform power induction at a current relative position, the power receiving end transmits a bit according to the level of the resonant receiving voltage A quasi-state signal is sent to the control unit to adjust a transmission current passing through the resonance transmission circuit, so that the resonance reception voltage is maintained at a target voltage level; wherein, the wireless power transmission system passes through the resonance transmission circuit according to the adjusted Sending current to determine an offset distance between the current relative position of the power receiving end and the power transmitting end and the optimal relative position.

In a preferred embodiment, the wireless power transmission system further includes a prompting device for prompting the offset distance, so as to provide a suggestion for the user to move the power receiving end.

In a preferred embodiment, the transmission current passing through the resonant transmission circuit after adjustment is related to a transmission coil current or a transmission coil voltage across the transmission coil; or, the power transmission end is again A resonant capacitor is included in series with the transmission coil, and the transmission current passing through the resonant transmission circuit after adjustment is related to the voltage across the resonant capacitor.

In a preferred embodiment, the offset distance is substantially positively correlated with the level of the transmitting coil current or the voltage across the resonant capacitor passing through the resonant transmitting circuit after adjustment.

In a preferred embodiment, the power transmission end further includes an inverter coupled between a first DC voltage and the resonant transmission circuit, and the control unit controls the inverter to convert the first DC voltage. A DC voltage is used to control the transmission current through the resonant transmission circuit; or, the power transmission end further includes a DC/DC converter coupled to the inverter for converting a second DC voltage to generate the first DC voltage A DC voltage is applied to the inverter to control the transmit current through the resonant transmit circuit.

In a preferred embodiment, the sending current through the resonant sending circuit is adjusted by one of the following methods: adjusting the duty ratio of the inverter; or, adjusting the operating frequency; or, the control unit controls the DC/DC converter to adjust the first DC voltage, so as to adjust the voltage provided by the inverter to the resonant transmission circuit.

In a preferred embodiment, the power transmitting end further includes a sensor for sensing the current of the transmitting coil, the voltage of the transmitting coil or the voltage across the resonant capacitor.

In a preferred embodiment, the sensor further receives a power-related signal from the control unit for normalizing the sending coil current, the sending coil voltage or the voltage across the resonant capacitor to The offset distance is determined, wherein the power related signal is related to the load of the power transmitter.

In a preferred embodiment, the wireless power transmission system further includes a prompting device, and the prompting device compares the normalized result with at least a threshold to generate an indication signal to provide the user with a prompt for moving the power receiving end. It is proposed, wherein the indicator signal corresponds to the offset distance.

In a preferred embodiment, the resonant receiving circuit generates the level state signal according to the difference between the target voltage level and the resonant receiving voltage.

In a preferred embodiment, the sensor also generates an effective power related signal according to the sending coil current and the sending coil voltage or the voltage across the resonant capacitor, which is used for the sending coil current and the sending coil voltage Or the voltage across the resonant capacitor is normalized to determine the offset distance, wherein the effective power related signal is related to the load of the power receiving end.

From another point of view, the present invention provides a wireless power transmission system, comprising: a power transmission end, including a resonance transmission circuit and a control unit, the control unit controls the resonance transmission circuit, wherein the resonance transmission circuit includes a transmitting coil and a resonant capacitor connected in series with the transmitting coil; and a power receiving end including a resonant receiving circuit, the resonant receiving circuit including a receiving coil for performing power induction with the transmitting coil by means of electromagnetic induction to A resonant receiving voltage is generated, and the power receiving end has an optimal relative position with respect to the power transmitting end; wherein, when the resonant transmitting circuit and the resonant receiving circuit perform power induction at a current relative position, the power receiving end is based on The level of the resonant receiving voltage sends a level state signal to the control unit to adjust a transmitting current through the resonant transmitting circuit, so that the resonant receiving voltage is maintained at a target voltage level; a sensor for sensing Measure a sending coil current of the sending coil and a sending coil voltage of the sending coil or a voltage across the resonant capacitor to generate a reactive power related signal; wherein the wireless power transmission system determines the reactive power related signal according to the reactive power related signal An offset distance between the current relative position of the power receiving end and the power transmitting end and the optimal relative position.

The following describes in detail through specific embodiments, and it should be easier to understand the purpose, technical content, characteristics and effects of the present invention.

Description of drawings

Figure 1 shows a schematic diagram of the relationship between the distance between the power transmitting end and the power receiving end, and the related energy loss;

Figures 2, 3, and 4 show schematic diagrams of multiple embodiments of the wireless power transmission system of the present invention;

5 is a schematic diagram showing the relationship between the transmission coil current and the offset distance in the wireless power transmission system of the present invention;

6 is a schematic diagram showing the relationship between the voltage across the resonant capacitor and the offset distance in the wireless power transmission system of the present invention;

7 is a schematic diagram showing the relationship between the cross-voltage of the resonant capacitor and the normalized curve with respect to the offset distance under different loads in the wireless power transmission system of the present invention;

8 and 9 show schematic diagrams of two embodiments of the wireless power transmission system of the present invention;

FIG. 10 shows a schematic diagram of an equivalent circuit of the wireless power transmission system of the present invention.

Detailed ways

The foregoing and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of a preferred embodiment with reference to the drawings. The drawings in the present invention are schematic, mainly intended to represent the functional relationship between each device and each element, and the shape, thickness and width are not drawn according to scale.

Please refer to Figure 2. In one aspect, the present invention provides a wireless power transmission system 100, comprising: a power transmitting end 10, including a resonance transmitting circuit 11 and a control unit 12, the control unit 12 controls the operation of the resonance transmitting circuit 11, wherein The resonant transmitting circuit 11 includes a transmitting coil 111; and a power receiving end 20, including a resonant receiving circuit 21, the resonant receiving circuit 21 includes a receiving coil 211, and the receiving coil 211 can conduct power induction with the transmitting coil 111 by means of electromagnetic induction to generate a resonant receiving voltage Vs. The resonant receiving circuit 21 has a target voltage level, and the target voltage level is the target voltage level at which the resonant receiving voltage Vs in the resonant receiving circuit 21 is to be maintained or adjusted when power induction is performed. In one embodiment, when the resonant transmitting circuit 11 and the resonant receiving circuit 21 perform power induction, the power receiving end 20 transmits a level state signal Sv to the control unit 12 according to the level of the resonant receiving voltage Vs, so as to adjust the resonant voltage Vs. The transmission current It of the transmission circuit 11 is used to make the power receiving end 20 maintain the target voltage level. For example, when the level of the resonant receiving voltage Vs is lower than the target voltage level, the power receiving end 20 transmits the level state signal Sv to the control unit 12 to increase the transmitting current It through the resonant transmitting circuit 11 , so that the power receiving end 20 The resonant receiving voltage Vs of is maintained at its target voltage level. Wherein, the level state signal Sv may be transmitted by, for example, a resonance control circuit in a manner such as wire, wireless, sound, or light.

In a preferred embodiment, the resonant receiving circuit 21 generates the level state signal Sv according to the difference between the aforementioned target voltage level and the resonant receiving voltage level Vs. The level state signal Sv is transmitted to the control unit 12 to adjust the transmission current It through the resonant transmission circuit 11 so that the power receiving end 20 maintains the target voltage level. For example, when the resonance reception voltage level Vs is significantly lower than the target voltage level, the generated level state signal Sv can significantly increase the transmission current It through the resonance transmission circuit 11 . Alternatively, when the resonant receiving voltage level Vs is slightly lower than the target voltage level, the generated level state signal Sv can slightly increase the transmission current It through the resonant transmitting circuit 11 . The method of adjusting the transmission current It through the resonance transmission circuit 11 will be described in detail later.

Generally speaking, in a wireless power transmission system (such as the wireless power transmission system 100 of the present invention), the relative positions of the power receiving end 20 and the power transmitting end 10 can be adjusted, and there is an optimal relative position. When the relative position of the terminal 20 and the power transmitting terminal 10 is in the best relative position, it can have the best power transmission efficiency. On the contrary, when the power receiving terminal 20 and the power transmitting terminal 10 are not aligned, that is, when the power receiving terminal 20 and When there is an offset distance between the current relative position of the power transmitting end 10 and the optimal relative position, the power transmission efficiency therebetween will decrease. From a point of view, the "best relative position" can also refer to a range of relative positions with better power transmission efficiency, for example, within the range of the "best relative position", the power transmission efficiency can reach a predetermined range. above the set efficiency value.

Continuing to refer to FIG. 2 , the wireless power transmission system 100 of the present invention can determine the offset distance between the power receiving end 20 and the power transmitting end 10 according to the adjusted transmit current It through the resonant transmitting circuit 11 . It should be noted that the “adjusted” transmission current It through the resonant transmission circuit 11 refers to the “adjustment” that is adjusted to maintain the resonant receiving voltage Vs of the power receiving end 20 at its target voltage level as described above. "After" the transmission current It through the resonant transmission circuit 11, in other words, the "adjusted" transmission current It through the resonant transmission circuit 11 refers to when the resonant reception voltage Vs of the power receiving end 20 has been maintained at its target voltage level. Send current It. The same applies to "adjusted" elsewhere in this document.

Referring to FIG. 3 , in a preferred embodiment, the wireless power transmission system 200 further includes a prompting device 30 , and the prompting device 30 is used for prompting or displaying the offset distance, so as to provide a suggestion for the user to move the power receiving end 20 , the user can appropriately move or change the relative position between the power receiving end 20 and the power transmitting end 10 according to the indication of the offset distance until the best relative position is reached, so as to obtain the best power transmission efficiency. The prompting device 30 can be installed on the same side of the power transmitting end 10 , or on the same side of the power receiving end 20 , or independent of the power transmitting end 10 and the power receiving end 20 , and the user can decide the setting method according to needs. In addition, the offset distance may be prompted or displayed by means of display, text, sound, light, or color.

Referring to FIG. 4 at the same time, in the wireless power transmission system 300 of this embodiment, the power transmitting end 10 further includes a resonant capacitor C connected in series with the transmitting coil 111 . Please refer to FIG. 3 and FIG. 4 at the same time, in a preferred embodiment, the aforementioned transmission current It is related to the transmission coil current IL passing through the transmission coil 111 , the transmission coil voltage VL or the cross-voltage Vc of the resonant capacitor C In other words, the transmission current It through the resonant transmission circuit 11 can be sensed and/or adjusted by sensing and/or adjusting the transmission coil current IL of the transmission coil 111 or the cross-voltage Vc of the resonance capacitor C.

In a preferred embodiment, when the power receiving end 20 is closer to the optimal relative position, the electromagnetic induction efficiency is better, so the transmission coil current passing through the transmission coil 111 after adjustment corresponding to the target voltage level The lower the voltage Vc across IL or resonant capacitor C is. Alternatively, when the power receiving end 20 is farther from the optimal relative position, its electromagnetic induction efficiency is lower, so the transmission coil current IL through the transmission coil 111 or the cross-voltage Vc of the resonance capacitor C after adjustment corresponding to the target voltage level higher. In other words, the aforementioned offset distance is substantially positively correlated with the level of the transmission coil current IL passing through the transmission coil 111 or the level of the cross-voltage Vc of the resonance capacitor C after adjustment.

5 and 6 respectively show the relationship between the sending coil current IL or the cross-voltage Vc of the resonant capacitor C and the offset distance when the power receiving end 20 has zero load. According to the figure, when the offset distance is closer to zero (that is, when the power receiving end 20 is closer to the optimal relative position), the adjusted transmitting coil current IL (the ordinate in FIG. 5 ) corresponding to the target voltage level is lower. , or the cross-voltage Vc of the resonant capacitor C (the ordinate in FIG. 6 ) is lower. Alternatively, when the offset distance increases (that is, the farther the power receiving end 20 is from the optimal relative position), the higher the adjusted transmitting coil current IL corresponding to the target voltage level, or the higher the voltage Vc across the resonant capacitor C. high. It is worth noting that the embodiments shown in FIGS. 5 and 6 may correspond to the operation characteristics of the wireless power transmission system in the signaling phase or the negotiation phase (when the power receiving end 20 has zero load or very light load). Since the value of the sending coil current IL or the voltage across the voltage Vc generally has a positive correlation with the offset distance, the value of the sending coil current IL or the voltage across the voltage Vc can be converted to obtain the corresponding offset distance, and the corresponding offset distance can be obtained through the prompting device 30 The offset distance is prompted or displayed to the user as a reference for the mobile power receiving end 20 , the details of which will be described in detail later.

Please continue to refer to FIG. 4 , in a preferred embodiment, the power transmitting end 10 further includes a sensor 16 , the transmitting coil current IL of the transmitting coil 111 , the transmitting coil voltage VL or the cross-voltage Vc of the resonant capacitor C mentioned above , which can be sensed by this sensor 16 .

4, in a preferred embodiment, the sensor 16 also receives a power-related signal PRS from the control unit 12, which is used to convert the transmission current It, the transmission coil current IL, the transmission coil voltage VL or the resonant capacitor C The cross-voltage Vc of Vc is normalized to determine the offset distance, wherein the power related signal PRS is a signal related to the load of the power transmitting end 10 . This load is, for example, related to the supply voltage, supply current or supply power of the power transmitting end 10 . From a viewpoint, this load is also related to the load of the power receiving end 20 at the same time.

Referring also to FIG. 7 , two curves are shown, which respectively represent the cross-voltage Vc1 of the adjusted resonant capacitor C with a higher load, and the cross-voltage Vc2 of the adjusted resonant capacitor C with a lower load. According to the curves Vc1 and Vc2, it can be known that regardless of the low load or high load, the larger the offset distance (that is, the farther the power receiving end 20 is from the optimal relative position), the higher the voltage across the resonant capacitor C is on the same curve; The smaller the moving distance (that is, the closer the power receiving end 20 is to the optimal relative position), the lower the voltage across the resonant capacitor C is. The curves Vc1 and Vc2 have the same trend of change. The purpose of normalization is to remove the load-related components in the curves Vc1 and Vc2 to generate a normalized characteristic curve (such as the dashed curve VcN in the figure), which is convenient for subsequent steps such as The normalized cross-voltage curve VcN value is converted into the value of the offset distance for user reference. It should be noted that the numerical values of the axes in FIGS. 5 , 6 and 7 are only examples, and do not limit the scope of the present invention.

According to Figures 5, 6 and 7 and their related descriptions, it can be known that regardless of the signaling stage or negotiation stage (corresponding to Figures 5 and 6, zero load), or the power transmission stage (corresponding to various load situations in Figure 7), it can be The technology of the present invention is applied to determine and instruct the user the offset distance, thereby facilitating the user to properly position the power transmitting end 10 and the power receiving end 20 in the wireless power transmission system.

Continuing to refer to FIG. 4 , in one embodiment, the prompting device 30 compares the normalized result VSN (for example, corresponding to the aforementioned VcN) with at least one threshold to generate an indication signal Sin to provide a suggestion for the user to move the power receiving end 20, Wherein the indication signal Sin corresponds to the offset distance. The threshold value may include a first threshold value corresponding to the best relative position, so as to determine whether the power receiving end 20 is located at the best relative position relative to the power transmitting end 10 . Alternatively, the threshold value may include a second threshold value to determine whether the power receiving end 20 is slightly far from the optimal power transmission position, so as to prompt the user to change the position of the power receiving end 20 . Alternatively, the threshold value may include a third threshold value to determine whether the power receiving end 20 is too far away from the optimal relative position. When it is too far away from the optimal relative position, in order to avoid the transmission current It passing through the resonant transmission circuit being too high. , can for example issue a warning and stop the power supply. The user can decide the required threshold according to different needs. In one embodiment, the indication signal Sin can be, for example, a multi-segment LED light signal corresponding to the offset distance, or a single LED light signal can be flashed at different rates to correspond to different offset distances. The power receiving end is, for example, a mobile phone, etc. In the embodiment, the indication signal may also indicate the corresponding offset distance through the display screen of the mobile phone.

From another viewpoint, in the wireless power transmission system according to the present invention, the operation characteristics of the power transmitting end 10 can be understood by a simplified calculation formula. Please refer to FIG. 10 , which shows an equivalent circuit diagram corresponding to the wireless power transmission system of the present invention (for example, corresponding to FIGS. 4 , 8 and 9 ), wherein the mutual inductance impedance Zeq of the power transmitting end 10 is calculated as follows:

ω is the operating frequency, RL is the load resistance, RS is the equivalent series resistance of the resonant receiving circuit 21 , LS is the equivalent inductance of the receiving coil 211 , and CS is the equivalent capacitance of the receiving coil 211 .

Wherein, LP is the equivalent inductance of the transmitting coil 111 , and k is the coupling coefficient between the transmitting coil 111 and the receiving coil 211 . When the power receiving end 20 is closer to the aforementioned optimum relative position, the value of the coupling coefficient k is higher; when the power receiving end 20 is farther from the aforementioned optimum relative position, the value of the coupling coefficient k is lower.

Through the transmission current It of the resonant transmission circuit 10, its calculation formula is as follows:

Among them, CP is the equivalent capacitance of the resonance capacitor C, and Vin is the input voltage of the resonance transmission circuit 11 .

The resonant receiving voltage Vs of the receiving coil 211 is calculated as follows:

V _s =jωM*It

In addition, the output voltage Vo of the resonance receiving circuit 21 is calculated as follows:

Among them, RL is the equivalent resistance of the output load of the resonance receiving circuit 21 .

According to the aforementioned calculation formula, it can be known that, on the premise that the transmission current It through the resonant transmission circuit 11 is adjusted so that the power receiving end 20 maintains its target voltage level, when the power receiving end 20 is closer to the optimal relative position ( The smaller the offset distance), the better the electromagnetic induction efficiency, the higher the mutual inductance impedance Zeq, and the lower the sent current It after adjustment. In other words, when the power receiving end 20 is closer to the optimal relative position, the lower adjusted transmit current It can make the power receiving end 20 maintain its target voltage level. Conversely, when the power receiving end 20 is farther from the optimal relative position (the larger the offset distance is), a higher adjusted transmit current It is required so that the power receiving end 20 can maintain its target voltage level.

In this way, no matter according to the diagram or the calculation formula, when the power receiving end 20 is closer to the optimal relative position, the adjusted transmission current It, the transmission coil current IL or the resonance capacitor corresponding to the target voltage level will pass through the resonant transmission circuit 10. The cross-voltage Vc of C is lower. Alternatively, when the power receiving end 20 is farther from the optimal relative position, the transmission current It, the transmission coil current IL or the cross-voltage Vc of the resonance capacitor C through the resonant transmission circuit 10 after adjustment corresponding to the target voltage level are all higher. .

Since the offset distance between the power receiving end 20 and the optimal relative position and its actual load condition can be reflected in the mutual inductance impedance Zeq of the power transmitting end 10 , specifically, the offset distance can be reflected in the mutual inductance impedance Zeq of the power transmitting end 10 . On the reactance of the power transmitting end 10, and the real load condition can be reflected on the resistance of the mutual inductance impedance Zeq of the power transmitting end 10, therefore, the effective power (or real power) or the inactive power (or imaginary power) of the power transmitting end 10 can be sensed by sensing power) to obtain information about the offset distance of the power receiving end 20 and its actual load.

Please continue to refer to FIGS. 4 , 8 and 9 , in one embodiment, the aforementioned power related signal PRS may include a real power related signal PRSR and/or a reactive power related signal PRSI. According to the present invention, in one embodiment, the sensor 16 shown in FIGS. 4 , 8 and 9 can generate an effective power related signal (for example, corresponding to FIG. 4, 8 and the effective power related signal PRSR of FIG. 9) to normalize the transmit coil current IL, the transmit coil voltage VL or the voltage across the resonant capacitor Vc to determine the offset distance, where the effective power related signal PRSR is related to The load of the power receiving end 20 .

In one embodiment, according to the present invention, the sensor 16 shown in FIGS. 4 , 8 and 9 can generate a reactive power related signal (for example, corresponding to FIG. 4, 8 and the reactive power related signal PRSI of FIG. 9), wherein the wireless power transmission system (eg 300, 400 or 500) of the present invention can determine the power receiving end 20 and the power transmitting end 10 according to the reactive power related signal PRSI The offset distance between the current relative position and the best relative position.

Referring to FIG. 8 , in a preferred embodiment of the wireless power transmission system 400 , the power transmitting end 10 further includes an inverter 14 coupled between a first DC voltage and the resonant transmitting circuit 11 , the control unit 12 controls the inverter 14 to convert the first DC voltage, thereby generating and controlling the transmission current It through the resonant transmission circuit 11 . The inverter 14 is connected to the transmitting coil 111 and the resonant capacitor C in parallel. Alternatively, referring to FIG. 9 , in a preferred embodiment of the wireless power transmission system 500 , the power transmitting end 10 further includes a DC/DC converter 15 for converting a second DC voltage to generate the first DC voltage to the inverter 14.

Further, in a preferred embodiment, the method of adjusting the transmission current It through the resonant transmission circuit 11 includes: adjusting the duty ratio of the inverter 14, and the duty ratio can increase or decrease the transmission The frequency spectrum of the transmitted electromagnetic signal generated by the coil 111 , that is, the degree of resonance is changed, thereby increasing or decreasing the power transmission from the power transmitting end 10 to the power receiving end 20 . For example, when the duty ratio is close to 50%, the power transmission from the power transmitter 10 to the power receiver 20 can be improved; or when the duty ratio is far from 50%, the power transfer from the power transmitter 10 to the power receiver 20 can be reduced. Alternatively, in one embodiment, adjusting the operating frequency of the inverter 14 can increase or decrease the degree of resonance of the transmitting electromagnetic signal generated by the transmitting coil 111 , thereby increasing or reducing the effect of the power transmitting end 10 on the power receiving end 20 . The power is transmitted, while the adjustment sends the current It. Alternatively, in one embodiment, the control unit 12 controls the DC/DC converter 15 to adjust the first DC voltage, thereby adjusting the voltage provided by the inverter to the resonant transmission circuit, thereby adjusting the transmission current It through the resonant transmission circuit 11 .

The present invention has been described above with respect to the preferred embodiments, but the above description is only for those skilled in the art to easily understand the content of the present invention, and is not intended to limit the scope of rights of the present invention. Within the same spirit of the present invention, various equivalent changes may be conceived by those skilled in the art. All of these can be derived by analogy according to the teachings of the present invention, so the scope of the present invention should cover the above and all other equivalent changes. In addition, it is not necessary for any embodiment of the present invention to achieve all objects or advantages, and thus neither should any claim be limited thereto. On the other hand, the contents of each embodiment can be used in an interactive combination, and any embodiment can refer to details of other embodiments.

Claims (9)

1. A wireless power transmission system, comprising: a power transmitting end including a resonance transmitting circuit and a control unit, the control unit controls the resonance transmitting circuit, wherein the resonance transmitting circuit includes a transmitting coil; and A power receiving end includes a resonant receiving circuit, the resonant receiving circuit includes a receiving coil, and is used for power induction with the transmitting coil by means of electromagnetic induction to generate a resonant receiving voltage, the power receiving end has a voltage relative to the power an optimal relative position of the sender; Wherein, when the resonant transmitting circuit and the resonant receiving circuit perform power induction at a current relative position, the power receiving end transmits a level state signal to the control unit according to the level of the resonant receiving voltage, so as to adjust the voltage through the resonant receiving circuit. a transmitting current of the resonant transmitting circuit, so that the resonant receiving voltage is maintained at a target voltage level; Wherein, the wireless power transmission system determines an offset distance between the current relative position of the power receiving end and the power transmitting end and the optimal relative position according to the transmission current passing through the resonant transmission circuit after adjustment; Wherein, the transmission current passing through the resonance transmission circuit after adjustment is related to a transmission coil current or a transmission coil voltage passing through the transmission coil; or, the power transmission end further includes a resonance capacitor connected in series with the transmission coil , wherein the transmission current passing through the resonant transmission circuit after the aforementioned adjustment is related to the cross-voltage of the resonant capacitor; Wherein, the power transmitting end further includes a sensor for sensing the current of the transmitting coil, the voltage of the transmitting coil or the voltage across the resonant capacitor; The sensor further receives a power related signal from the control unit for normalizing the transmitting coil current, the transmitting coil voltage or the voltage across the resonant capacitor to determine the offset distance, wherein the power related signal is related to load on the power transmitter. 2 . The wireless power transmission system of claim 1 , wherein the wireless power transmission system further comprises a prompting device, the prompting device is used for prompting the offset distance to provide a user with a suggestion for moving the power receiving end. 3 . 3 . The wireless power transmission system of claim 1 , wherein the offset distance is substantially positively correlated with the adjusted level of the transmitting coil current or the voltage across the resonant capacitor through the resonant transmitting circuit. 4 . 4. The wireless power transmission system of claim 3, wherein the power transmitting end further comprises an inverter coupled between a first DC voltage and the resonant transmitting circuit, and the control unit controls the inverter to use Controlling the sending current through the resonant sending circuit by converting the first DC voltage; or, the power sending end further includes a DC/DC converter coupled to the inverter for converting a second DC voltage The transmission current through the resonant transmission circuit is controlled to generate the first DC voltage to the inverter. 5. The wireless power transmission system of claim 4, wherein the transmission current through the resonant transmission circuit is adjusted in one of the following ways: adjusting the duty cycle of the inverter; or, adjusting the operating frequency; or, the control unit controls the DC/DC converter to adjust the first DC voltage, so as to adjust the voltage provided by the inverter to the resonant transmission circuit. 6. The wireless power transmission system of claim 1, further comprising a prompting device, the prompting device compares the normalized result with at least a threshold to generate an indication signal to provide a user with a suggestion for moving the power receiving end, Wherein the indicator signal corresponds to the offset distance. 7 . The wireless power transmission system of claim 1 , wherein the resonant receiving circuit generates the level state signal according to a difference between the target voltage level and the resonant receiving voltage. 8 . 8 . The wireless power transmission system of claim 1 , wherein the sensor further generates an effective power-related signal according to the transmission coil current and the transmission coil voltage or the cross-voltage of the resonance capacitor, which is used for the transmission coil current, the transmission coil current, the transmission coil current, and the transmission coil current. The transmit coil voltage or the voltage across the resonant capacitor is normalized to determine the offset distance, where the effective power related signal is related to the load at the power receiving end. 9. A wireless power transmission system, comprising: a power transmitting end including a resonance transmitting circuit and a control unit, the control unit controls the resonance transmitting circuit, wherein the resonance transmitting circuit includes a transmitting coil and a resonance capacitor connected in series with the transmitting coil; A power receiving end includes a resonant receiving circuit, the resonant receiving circuit includes a receiving coil, and is used for power induction with the transmitting coil by means of electromagnetic induction to generate a resonant receiving voltage, the power receiving end has a voltage relative to the power an optimal relative position of the sender; Wherein, when the resonant transmitting circuit and the resonant receiving circuit perform power induction at a current relative position, the power receiving end transmits a level state signal to the control unit according to the level of the resonant receiving voltage, so as to adjust the voltage through the resonant receiving circuit. a transmit current of the resonant transmit circuit, so that the resonant receive voltage is maintained at a target voltage level; and a sensor for sensing a sending coil current of the sending coil and a sending coil voltage of the sending coil or a voltage across the resonance capacitor to generate a reactive power related signal; Wherein, the wireless power transmission system determines an offset distance between the current relative position of the power receiving end and the power transmitting end and the optimal relative position according to the reactive power related signal.

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