Wireless charging optimization method and system

Abstract

The invention relates to a wireless charging optimization method and system. According to the method, a wireless induction electric energy transmission circuit impedance model is constructed, a time domain periodic steady-state problem is converted into a frequency domain linear matrix equation for solving output power, and the process comprises the following steps: selecting a harmonic wave truncation order, and defining the harmonic wave order in a range determined by the harmonic wave truncation order; constructing a diagonal impedance matrix of a resistor, an inductor and a capacitor in the wireless induction power transmission circuit and a Toeplitz impedance matrix of an active switch; a total impedance matrix equation is constructed based on a wireless induction power transmission circuit topology and an element impedance matrix, a system equation is constructed by using a total impedance matrix and a direct current voltage vector, and nonlinear reflection impedance is solved through an iteration method; calculating output power and output power volatility under different coupling coefficients by using the nonlinear reflection impedance; and optimizing target design parameters of the wireless induction electric energy transmission circuit by taking minimization of the power fluctuation ratio as a target so as to stabilize the output power in the charging process.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of wireless charging, in particular to a wireless charging optimization method and system. BACKGROUND

[0002] With the continuous development of technology, wearable devices that can be charged, such as smart rings, are becoming more and more popular. The current smart ring has the following charging methods, one is contact charging, by reserving two charging contact points on the smart ring, and then using a dedicated charger to connect the contact points of the smart ring to charge the smart ring, the other is wireless charging in the traditional sense, which needs to use a wireless power supply device to charge the smart ring. Wireless inductive power transmission is based on the principle of electromagnetic induction, which realizes energy transmission through the coupling of high-frequency alternating magnetic field in space, generally including two parts of the transmitting end and the receiving end, the transmitting end converts direct current power into high-frequency alternating current power, and generates an alternating magnetic field through the transmitting coil; the receiving end captures the magnetic field energy through the receiving coil, and charges after rectification and filtering; it is an important implementation way of non-contact energy transmission for wearable devices that can be charged. Compared with the traditional contact charging method, wireless inductive power transmission has the advantages of convenient use, high safety, good environmental adaptability, etc., avoiding the problems inherent in traditional connection methods such as plug-in wear and tear, contact contamination. However, the wireless inductive power transmission device is sensitive to the coupling coefficient between the transmitting end and the receiving end, and the change of the coupling coefficient is difficult to avoid in actual application, for example, the deviation of the position between the transmitting end and the receiving end, the change of the distance, the existence of foreign matter between the transmitting end and the receiving end coils, etc. will cause the change of the coupling coefficient, and the change of the coupling coefficient will cause the output power fluctuation, affecting the efficiency and stability of the power transmission process.

[0003] To cope with the above challenges, one way is to detect the output power / voltage / current in real time, and dynamically adjust the switching frequency fs, duty cycle D or phase angle. Although it can improve the robustness, it needs high-speed communication (TX RX bidirectional), complex sensing circuit and real-time controller, which significantly increases the system cost and reduces the reliability, and the control delay may cause transient instability.

[0004] Another way is to use a multi-stage compensation topology, using LCL, LCL-S, S-S, etc. High-order network to improve system decoupling ability. However, the compensation network has many elements, sensitive parameters, large volume / weight, and it is still difficult to achieve <20% power fluctuation under weak coupling.

[0005] Therefore, a wireless charging optimization method is needed that does not require real-time feedback, does not require complex topology, and can achieve high-stable output and high efficiency under extremely weak coupling through feedforward design. SUMMARY

[0006] To solve the above technical problems or at least partially solve the above technical problems, the application provides a wireless charging optimization method and system.

[0007] In a first aspect, the application provides a wireless charging optimization method applied to a wireless inductive power transmission circuit, the wireless inductive power transmission circuit including a transmitting end and a receiving end. To describe the time-varying nonlinear characteristics of an active switch S of the wireless inductive power transmission circuit and the harmonic interaction of the system, an impedance model of the wireless inductive power transmission circuit is constructed, and a time-domain periodic steady-state problem is converted into a frequency-domain linear matrix equation to solve the output power. The process includes: selecting a harmonic truncation order N, defining a harmonic order n∈[ N, N]; constructing a diagonal impedance matrix of resistors, inductors, and capacitors in the wireless inductive power transmission circuit and a Toeplitz impedance matrix of the active switch S; constructing a total impedance matrix equation based on the circuit topology and element impedance matrix of the wireless inductive power transmission circuit, constructing a system equation using the total impedance matrix and a direct-current voltage vector, and solving the nonlinear reflected impedance by an iterative method; and calculating the output power and the output power fluctuation rate under different coupling coefficients k using the nonlinear reflected impedance. To minimize the power fluctuation rate, the target design parameters of the wireless inductive power transmission circuit that follow the constant zero voltage switching constraint are optimized, including: a resonance frequency ratio K, reactances of a transmitting coil Coil1 and a resonance capacitor C2 in an LC series resonance circuit of the transmitting end , a duty cycle D of the active switch S, and reactances of a receiving coil Coil2 and a capacitor C3 of the receiving end ; to stabilize the output power, reactances are introduced into the LC series resonance circuit of the transmitting end , and a mismatch design is performed on the receiving end; the mismatch of the receiving end causes the receiving end to work in a set inductive state, and the reflected impedance of the receiving end to the transmitting end is capacitive. The imaginary part of the capacitive reflected impedance is used to compensate for the impedance change of the transmitting end, thereby maintaining the stability of the output power.

[0008] Further, the transmitting end includes: a direct-current power supply Vd connected to a radio frequency choke L1 and an active switch S; the active switch S is connected in parallel with a capacitor C1, the capacitor C1 is connected in parallel with an LC series resonance circuit, and the LC series resonance circuit includes a transmitting coil Coil1 and a resonance capacitor C2; and the transmitting coil Coil1 is coupled to the receiving end.

[0009] Further, the receiving end includes: a receiving coil Coil2 connected to a capacitor C3 and a charging circuit, and the receiving coil Coil2 is coupled to the transmitting end.

[0010] Further, according to the wireless inductive power transmission circuit, the reactance introduced into the LC series resonance circuit of the transmitting end is represented as follows: ; satisfy, ; in, The reactance of the transmitting coil Coil1 and the resonant capacitor C2 in the LC series resonant circuit of the transmitting end; The inductance value of the transmitting coil Coil1, The capacitance value of the resonant capacitor C2 is... The switching angular frequency of the active switch S is determined by introducing a non-zero value. This is done to optimize output stability.

[0011] Furthermore, in the wireless inductive power transmission circuit, the reactance introduced by the inductive detuning of the receiving coil Coil2 and capacitor C3 at the receiving end is expressed as follows: ; satisfy, ; in, The reactance of the receiving coil Coil2 and capacitor C3; The inductance value of the receiving coil Coil2, This is the capacitance value of the resonant capacitor C3. The switching angular frequency of the active switch S. For the load resistance, by introducing a non-zero... This is done to optimize output stability.

[0012] Furthermore, the diagonal impedance matrix of any resistor R is as follows: Where B is the total dimension, B=2N+1, and N is the harmonic cutoff order; Diagonal impedance matrix of any inductor L The diagonal is as follows: ; Wherein, the nth order impedance is The impedance of the DC component is 0; The diagonal of the diagonal impedance matrix of any capacitor C is as follows: ; When n is not zero, the nth order impedance is The DC component is set as the maximum resistance. Simulates the DC blocking characteristics of a capacitor; The active switch S is modeled as a periodic time-varying resistor, and its Fourier coefficients are: ; The impedance matrix of the active switch S is then the Toeplitz matrix. The elements of the Toeplitz matrix are as follows: .

[0013] Further, the total impedance matrix equation is: ; Where: ; are the diagonal impedance matrices of the transmitting coil Coil1 and the resonant capacitor C2, respectively; The DC voltage vector is: ; Where the DC voltage is located at the N+1th position of the DC voltage vector, corresponding to n = 0; The system equation is: .

[0014] Further, in the wireless inductive power transmission circuit, the switching frequency of the active switch S is ; the transmitting coil Coil1 resonates with the resonant capacitor C2 at the switching frequency , that is: , The resonant frequency ratio between the radio frequency choke L1 and the capacitor C1 and the LC series resonance circuit affects the zero voltage switching condition of the active switch S, and the zero voltage switching is limited by adjusting the resonant frequency ratio; wherein the resonant frequency of the radio frequency choke L1 and the capacitor C1 is: ; The relationship between the LC series resonance circuit is: , then the resonant frequency ratio is: .

[0015] Further, the nonlinear iterative solution of the nonlinear reflected impedance includes: S401, initialize a receiving end reactance guess value , then the initialized total impedance of the receiving end is: ; S402, calculate the initialized reflected impedance according to the double coil mutual inductance model ; S403, solve the total impedance using the initialized reflected impedance and construct the system equation ; S404, extract the receiving end voltage , calculate the receiving current ; S405, updating the next step of the receiving end total impedance by using the receiving end voltage and the receiving end current ; S406, repeating steps S402-S405 until wherein x is the iteration count-1, is the total impedance convergence threshold.

[0016] In a second aspect, the present application provides a wireless charging optimization system, comprising: a direct current power supply Vd connected to a radio frequency choke L1 and an active switch S; the active switch S is connected in parallel with a capacitor C1, the capacitor C1 is connected in parallel with an LC series resonance circuit, the LC series resonance circuit comprises a transmitting coil Coil1 and a resonance capacitor C2; the transmitting coil Coil1 is coupled to a receiving end; the receiving end comprises: a receiving coil Coil2 connected to a capacitor C3 and a charging circuit, the receiving coil Coil2 is coupled to the transmitting end; the transmitting end and the receiving end work according to the target design parameters, and the wireless charging optimization method is realized.

[0017] The above technical solution provided by the embodiments of the present application has the following advantages compared with the prior art: The transmitting end and the receiving end of the present application simultaneously adopt inductive detuning design, the detuning of the receiving end makes the receiving end work in a set inductive state, the reflected impedance reflected by the receiving end to the transmitting end is capacitive, the imaginary part of the capacitive reflected impedance is used to compensate the impedance change of the transmitting end, the output power is maintained stable, and the output power is maintained stable in a wide coupling range; under weak coupling conditions, the efficiency of more than 85% can still be maintained after introducing reactance. BRIEF DESCRIPTION OF DRAWINGS

[0018] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application.

[0019] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows, and obviously, other drawings can also be obtained by those skilled in the art without creative labor under the premise of not paying the creative labor.

[0020] Figure 1 A flowchart of the wireless charging optimization method provided by the embodiments of the present application; Figure 2 A flowchart of the iterative calculation of the reflected impedance provided by the embodiments of the present application; Figure 3 A schematic diagram of a wireless charging optimization system provided by the embodiments of the present application. DETAILED DESCRIPTION

[0021] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present application with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative effort belong to the scope of protection of the present application.

[0022] It should be noted that, in this document, the terms "comprising", "containing", or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a list of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent in such a process, method, article, or device. Without more limitations, the element defined by the phrase "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or device that includes the element.

[0023] Embodiment 1 The present application provides a wireless charging optimization method applied to the optimization of a wireless induction power transmission circuit.

[0024] As shown in Figure 2 , the wireless induction power transmission circuit includes a transmitting end and a receiving end. The transmitting end includes a direct current power supply Vd, which provides a direct current voltage . The direct current power supply Vd is connected to a radio frequency choke L1 and an active switch S, and the active switch S is connected in parallel with a capacitor C1. The inductance value of the radio frequency choke L1 is , and the capacitance value of the capacitor C1 is . The duty cycle of the active switch S is D, the switching frequency is , the switching angular frequency is , and the voltage across the active switch S is . The capacitor C1 is connected in parallel with an LC series resonant circuit, and the LC series resonant circuit includes a transmitting coil Coil1 and a resonant capacitor C2. The transmitting coil Coil1 is wirelessly electromagnetically coupled to the receiving end, and the inductance value of the transmitting coil Coil1 is , and the capacitance value of the resonant capacitor C2 is In this application, the transmitting coil Coil1 and the resonant capacitor C2 introduce reactance.

[0025] The receiving end includes a receiving coil Coil2, which is connected to a capacitor C3 and a charging circuit, and the receiving coil Coil2 is electromagnetically coupled to the transmitting coil of the transmitting end. The inductance value of the receiving coil Coil2 is The capacitance value of the capacitor C3 is In the present application, the transmitting coil Coil2 and the capacitor C3 introduce reactance.

[0026] The wireless inductive power transmission circuit described above operates under traditional working conditions, so that the voltage across the active switch S is a "soft switching" sine wave, the switching loss tends to zero, and the system efficiency can reach more than 95%, but the output is unstable due to the association of the output with the load, which is analyzed as follows: The traditional working conditions of wireless inductive power transmission require that the active switch S realizes zero-voltage switching, that is, at the moment of switch-on, the drain-source voltage of the active switch S , and ; the load is a constant pure resistance R L ; the resonant network is strictly tuned to the switching angular frequency ; the switching duty cycle D and the component parameters ( , ) satisfy certain constraint equations (such as , ) to achieve optimal efficiency.

[0027] According to the constraint equation, the above working conditions are sensitive to load changes; to overcome the sensitivity to load changes, an additional auxiliary LC resonant bypass is introduced, so that the output current or the voltage remains constant within a certain load range, that is, to achieve: ; However, when the circuit with an additional auxiliary LC resonant bypass is applied to wireless inductive power transmission, its ability to keep the output current or voltage constant within a certain load range is sharply attenuated or even completely lost in a weak coupling scenario. The reason is that the load of wireless inductive power transmission is not a directly physically connected resistor, but an equivalent impedance reflected to the transmitting end through magnetic coupling. According to the double-coil mutual inductance model, the reflected impedance expression is: ; where: is the mutual inductance, ; k ∈ [0, 1] is the coupling coefficient, and the coupling coefficient k of a typical EV wireless charging ranges from 0.05 to 0.25; is the total impedance of the receiving end, , is the conjugate of the total impedance of the receiving end; is the net reactance of the receiving end.

[0028] When the receiving end is strictly resonant, that is, = 0, the reflected impedance is purely resistive: ; According to the above formula, the impedance is purely resistive, is proportional to the square of the coupling coefficient k, and under the condition of weak coupling (such as k ranges from 0.04 to 0.07), the change will be nearly 3 times. It is determined by the realization of the zero-voltage switching condition and the voltage stress limit to meet the minimum reflection resistance constraint. And when the minimum reflection resistance is less than the minimum reflection resistance, the system will lose the realization of the zero-voltage switching condition; the voltage waveform of the active switch S is distorted, the fundamental component is reduced, and the harmonic content is increased; the output power fluctuates sharply. Therefore, a wireless charging optimization method is needed to find the target design parameters, which can make the wireless inductive power transmission circuit output stable even under the condition of weak coupling.

[0029] In order to accurately describe the time-varying nonlinear characteristics of the active switch S of the wireless inductive power transmission circuit and the harmonic interaction of the system, as shown in Figure 1 , the wireless charging optimization method provided by the present application constructs an impedance model of the wireless inductive power transmission circuit, converts the time-domain periodic steady-state problem into a frequency-domain linear matrix equation to solve the output power, and the process includes.

[0030] S100, selecting a harmonic truncation order N, defining a harmonic order n∈[ N, N]; An example value of the selected harmonic truncation order N is N=5, the harmonic order n∈[ 5,5], and the total dimension B is 2N+1=11.

[0031] S200, constructing an element impedance matrix. The diagonal impedance matrix of the resistance, inductance and capacitance in the wireless inductive power transmission circuit and the Toeplitz impedance matrix of the active switch S are constructed.

[0032] Specifically, the diagonal impedance matrix of any resistance R is as follows: ; The diagonal of the diagonal impedance matrix of any inductance L is as follows, ; wherein the nth order impedance is , the direct current component (i.e. the n=0 order impedance) is 0, and it is naturally satisfied.

[0033] The diagonal of the diagonal impedance matrix of any capacitance C is as follows, ; wherein when n is not zero, the nth order impedance is , and the direct current component is set to be a maximum resistance ​, simulate the capacitor direct-current isolation characteristic.

[0034] The active switch S is modeled as a periodic time-varying resistance, whose Fourier coefficients are: ; The impedance matrix of the active switch S is a Toeplitz matrix , the elements of the Toeplitz matrix are as follows:

[0035] S300, based on the wireless inductive power transmission circuit circuit topology and element impedance matrix to construct the total impedance matrix equation, using the total impedance matrix, direct current voltage vector to construct the system equation, by iterative method to solve the nonlinear reflection impedance.

[0036] Wherein, the total impedance matrix equation is: ; Wherein: ; The diagonal impedance matrix of the transmitting coil Coil1 and the resonance capacitor C2 respectively; The direct current voltage vector is: ; Wherein, the direct current voltage Located in the N+1th position of the direct current voltage vector.

[0037] The system equation is: ; S400, nonlinear iterative solution of nonlinear reflection impedance. Because Dependence on the receiving current, iterative calculation, as Figure 2 Shown, including: S401, initialize a receiving end reactance guess value : the initialized receiving end total impedance is: ; S402, according to the double coil mutual inductance model to calculate the initialized reflection impedance ; S403, using the initialized reflection impedance to solve the total impedance and construct the system equation ; S404, extract the receiving end voltage Calculate the receiving current ; S405, using the receiving end voltage and the receiving end current, update the receiving end total impedance of the next step ; S406, repeat steps S402-S405 until wherein x is an iteration count - 1, is a total anti-convergence threshold.

[0038] S500, calculate the output power and output power fluctuation rate under different coupling coefficients k.

[0039] The design parameters of the wireless inductive power transmission circuit are optimized with the minimum power fluctuation rate as the target: the resonance frequency ratio K, the reactance of the transmitting coil Coil1 and the resonance capacitor C2 in the LC series resonance circuit of the transmitting end , the duty cycle D of the active switch S, and the reactance of the receiving coil Coil2 and the capacitor C3 of the receiving end ; with the output power stability as the target, the reactance X tx is introduced into the LC series resonance circuit of the transmitting end; the detuning design of the receiving end makes the receiving end work in a set inductive state, and the receiving end reflects a capacitive reflected impedance to the transmitting end, which compensates for the impedance change of the transmitting end using the imaginary part of the capacitive reflected impedance, and maintains the output power stable.

[0040] Resonance frequency ratio K: in the wireless inductive power transmission circuit, the active switch S performs switching action under zero voltage condition, and the switching frequency is ; the transmitting coil Coil1 resonates with the resonance capacitor C2 at the switching frequency , that is: , The resonance frequency of the radio frequency choke L1 and the capacitor C1, and the resonance frequency ratio between the LC series resonance circuits affect the zero voltage switching condition of the active switch S. By adjusting the resonance frequency ratio to limit the zero voltage switching, the influence of the reactance introduction on the zero voltage switching is minimized; wherein the resonance frequency of the radio frequency choke L1 and the capacitor C1 is: ; The relationship between the LC series resonance circuits is: , and the resonance frequency ratio is: .

[0041] Under the target design parameters, the receiving coil Coil2 and the capacitor C3 form an inductive detuning, which satisfies: ; Under the target design parameters, the reactance introduced into the LC series resonance circuit of the transmitting end satisfies ; wherein is the reactance of the transmitting coil Coil1 and the resonance capacitor C2 in the LC series resonance circuit of the transmitting end; is the inductance value of the transmitting coil Coil1, C2 is the capacitance value of the resonance capacitor C2, ωs is the switching angular frequency of the active switch S, by introducing a non-zero to perform output stability optimization.

[0042] By optimizing the target design parameters, the system meets the following conditions simultaneously within a certain range of load resistance R L : constant zero voltage switching, i.e., the active switch is turned on at the moment; constant output, i.e., low output power fluctuation.

[0043] Specifically, in high-frequency steady state, the output current of the wireless inductive power transmission circuit is a sine fundamental wave: ; wherein the duty cycle of the active switch S is D, the active switch S is turned on: ; the active switch S is turned off: ; during the off period of the active switch S , all the current flows into the capacitor C1.

[0044] According to the current-voltage relationship of the capacitor, the voltage across the active switch S is derived as: V2=V1+Vc1 and during the off period of the active switch S , we have: ; wherein, is the phase difference between the current and the switch, according to the zero voltage switching condition, .

[0045] A normalized parameter is introduced to eliminate the dimensional dependence of voltage / current; wherein the normalized current parameter is: ; the normalized voltage parameter is: ; wherein, the normalized voltage parameter is the ratio of the peak voltage across the active switch to the input voltage, which directly determines the device stress and the robustness of zero voltage switching.

[0046] The Fourier transform is used to decompose the voltage across the active switch into a resistive component corresponding to the load power transmission and a reactive component corresponding to the non-functional energy exchange for maintaining the ZVS waveform. Specifically, the Fourier transform is used to expand the voltage across the active switch in period: ; then the fundamental component is: ; The resistive component and the reactive component of the impedance decoupling are as follows, respectively; Resistive branch voltage: ; Reactive branch voltage: ; The resistive branch voltage determines the output power; the reactive branch voltage determines the switch voltage waveform, and needs to match the reactance to offset the reactive power of the transmitting coil Coil1.

[0047] Constant zero voltage switch constraint: The constant zero voltage switch constraint requires And .

[0048] Equivalent to ; Substitute into the reactive branch voltage elimination variable : ; The reactive branch voltage is irrelevant to α, .

[0049] Constant output power constraint: Output power ; Substitute , and the following is obtained: In order to eliminate dependence, it is necessary to , because , finally equivalent to: .

[0050] The transmitting end and the receiving end of the application simultaneously adopt inductive detuning design. The detuning of the receiving end makes the receiving end work in a set inductive state. The reflected impedance reflected by the receiving end to the transmitting end is capacitive. The imaginary part of the capacitive reflected impedance is used to compensate the impedance change of the transmitting end, so as to maintain the stability of the output power. The physical mechanism is as follows: on the one hand, the stability brought by the impedance shaping effect of the inductive detuning of the receiving end: It can be known from the following reflected impedance formula: ; When is greater than 0,

[0051] Compared with the resonance case when is equal to 0, because the denominator increases, the reflected impedance The absolute value decreases, but its relative rate of change ( The effect weakens significantly with the change of coupling coefficient k; the total impedance magnitude at the receiver is significantly reduced. Increasing the current at the receiving end leads to a decrease in the current at the transmitting end, which slows down the current fluctuations at the transmitting end, smooths the current waveform, and avoids current spikes that may be caused by capacitive detuning.

[0052] On the other hand, the stability is provided by the voltage support effect of the transmitter's detuning: In a wireless inductive power transmission circuit, the voltage across the active switch S is... The current through capacitor C1 Decide: ; Current in capacitor C1 It consists of two parts: the component of the fundamental current flowing to the load after being filtered by the RF choke L1, and the pulse current during the conduction of the active switch S.

[0053] when of When the denominator increases and the current decreases, the load current at the transmitter increases, and the current in capacitor C1... The amplitude increases. Increase the voltage across the active switch S The waveform will "steepen". This can be achieved by adjusting the transmitter settings. A value greater than 0 effectively increases the impedance of the transmitting circuit and suppresses the current in capacitor C1. The dynamic range of change maintains the voltage across the active switch S. Waveform stability.

[0054] Individual adjustment or The effect is limited. This invention achieves minimization of reflection impedance by jointly optimizing both factors. The coupling coefficient k sensitivity; the voltage across the active switch S Robustness of amplitude and zero-crossing characteristics; output power P out The sensitivity to changes in the coupling coefficient k is significantly reduced.

[0055] Example 2 like Figure 3As shown, the application provides a wireless charging optimization system, comprising: a direct current power supply Vd connected with a radio frequency choke L1 and an active switch S; the active switch S is connected with a capacitor C1 in parallel, the capacitor C1 is connected with an LC series resonance circuit in parallel, the LC series resonance circuit comprises a transmitting coil Coil1 and a resonance capacitor C2; the transmitting coil Coil1 is coupled with a receiving end; the receiving end comprises: a receiving coil Coil2 connected with a capacitor C3 and a charging circuit, the receiving coil Coil2 is coupled with the transmitting end; the transmitting end and the receiving end work according to target design parameters; any wireless charging optimization method is realized.

[0056] In the embodiments of the present application, it should be understood that the disclosed structure and method can be implemented in other ways. For example, the structural embodiments described above are only schematic, for example, the division of the units is only a logical function division, and actual implementation can have another division manner, for example, a plurality of units or components can be combined or integrated into another system, or some features can be ignored or not executed. In addition, the coupling or direct coupling or communication connection between the units shown or discussed can be indirect coupling or communication connection through some interface, structure or unit, and can be electrical, mechanical or other forms.

[0057] The units described as separate components can or can not be physically separate, and the components shown as units can or can not be physical units, that is, they can be located in one place, or can be distributed on a plurality of network units. Part or all of the units can be selected according to actual needs to achieve the purpose of the embodiment.

[0058] In addition, the functional units in each embodiment of the present application can be integrated in one processing unit, or each unit can be physically present separately, or two or more units can be integrated in one unit. The integrated unit can be realized in the form of hardware or in the form of software functional unit.

[0059] The above is only a specific embodiment of the present application, which enables those skilled in the art to understand or implement the present application. Various modifications of these embodiments will be apparent to those skilled in the art, and the general principles defined herein can be implemented in other embodiments without departing from the spirit or scope of the present application. Therefore, the present application will not be limited to these embodiments shown herein, but will conform to the widest scope consistent with the principles and novel features applied herein.

Claims

1. A wireless charging optimization method, characterized in that, The application is applied to a wireless inductive power transmission circuit, the wireless inductive power transmission circuit includes a transmitting end and a receiving end, in order to describe time-varying nonlinear characteristics of an active switch S of the wireless inductive power transmission circuit and harmonic interaction of the system, an impedance model of the wireless inductive power transmission circuit is constructed, a time domain periodic steady-state problem is converted into a frequency domain linear matrix equation to solve output power, and the process includes: selecting a harmonic truncation order N, defining a harmonic order n [in N, N]; constructing a diagonal impedance matrix of resistance, inductance and capacitance in the wireless inductive power transmission circuit and a Toeplitz impedance matrix of the active switch S; constructing a total impedance matrix equation based on a circuit topology of the wireless inductive power transmission circuit and an element impedance matrix, constructing a system equation by using the total impedance matrix and a direct current voltage vector, and solving nonlinear reflected impedance by using an iterative method; and calculating output power and output power fluctuation rate under different coupling coefficients k by using the nonlinear reflected impedance. Optimizing target design parameters of a wireless inductive power transfer circuit following constant zero voltage switching constraint, including: a resonant frequency ratio K, reactance of a transmitting coil Coil1 and a resonant capacitor C2 in an LC series resonant circuit at a transmitting end , duty cycle D of an active switch S, reactance of a receiving coil Coil2 and a capacitor C3 at a receiving end ; introducing reactance in the LC series resonant circuit at the transmitting end to stabilize output power , a detuning design for the receiving end; the detuning of the receiving end makes the receiving end work in a set inductive state, the receiving end reflects a capacitive reflected impedance to the transmitting end, the imaginary part of the capacitive reflected impedance is used to compensate impedance variation of the transmitting end to maintain stable output power.

2. The wireless charging optimization method of claim 1, wherein, The transmitting end comprises: a direct current power supply Vd connected with a radio frequency choke L1 and an active switch S; the active switch S is connected with a capacitor C1 in parallel, the capacitor C1 is connected with an LC series resonance circuit in parallel, the LC series resonance circuit comprises a transmitting coil Coil1 and a resonance capacitor C2; the transmitting coil Coil1 is coupled with the receiving end.

3. The wireless charging optimization method of claim 1, wherein, The receiving end comprises: a receiving coil Coil2 connected with a capacitor C3 and a charging circuit, the receiving coil Coil2 is coupled with the transmitting end.

4. The wireless charging optimization method of claim 2, wherein, According to the wireless inductive power transmission circuit, the reactance introduced by the LC series resonance circuit in the transmitting end is represented as follows: ； satisfy, ; wherein, is the reactance of the transmit coil Coil1 and the resonant capacitor C2 in the transmit end LC series resonant circuit; is the inductance value of the transmit coil Coil1, is the capacitance value of the resonant capacitor C2, is the switching angular frequency of the active switch S, by introducing a non-zero for output stability optimization.

5. The wireless charging optimization method of claim 3, wherein, According to the wireless inductive power transmission circuit, the reactance introduced by the inductive detuning of the receiving coil Coil2 and the capacitor C3 in the receiving end is represented as follows: ； satisfy, ; wherein, is the reactance of the receiving coil Coil2 and the capacitor C3; is the inductance value of the receiving coil Coil2, is the capacitance value of the resonance capacitor C3, is the switching angular frequency of the active switch S, is the load resistance, by introducing a non-zero for output stability optimization.

6. The method of claim 1, wherein, The diagonal impedance matrix of any resistor R is as follows: where B is the total dimension, B = 2N + 1, N is the harmonic truncation order; The diagonal impedance matrix of any inductance L is given by The diagonal is given by ； wherein the nth order impedance is , and the impedance of the DC component is 0; The diagonal of the diagonal impedance matrix of any capacitor C is as follows, ； Wherein, n is not zero, the nth order impedance is , the DC component is set to the maximum resistance , analog capacitor direct current isolation characteristics; The active switch S is modeled as a periodic time-varying resistor, and the Fourier coefficient of the active switch S is as follows: ； The impedance matrix of the active switch S is a Toeplitz matrix The elements of the Toeplitz matrix are as follows: 。 7. The wireless charging optimization method of claim 6, wherein, The total impedance matrix equation is as follows: ； wherein: ; are the diagonal impedance matrices of the transmit coil Coil1 and the resonance capacitor C2, respectively; The direct current voltage vector is as follows: ； wherein the direct current voltage is located at the N+1th position of the direct current voltage vector, corresponding to n = 0; The system equation is as follows: 。 8. The method of claim 1, wherein, In the wireless inductive power transfer circuit, the switching frequency of the active switch S is ; the transmitting coil Coil1 resonates with the resonant capacitor C2 at the switching frequency , i.e. ， The resonance frequency ratio between the resonance frequency of the radio frequency choke L1 and the capacitor C1 and the resonance frequency between the LC series resonance circuit affects the zero voltage switching condition of the active switch S, and the zero voltage switching is limited by adjusting the resonance frequency ratio; wherein the resonance frequency of the radio frequency choke L1 and the capacitor C1 is as follows: ； The relationship between the LC series resonant circuits is: The resonant frequency ratio is: 。 9. The method of claim 1, wherein, The nonlinear iterative method is used to solve the nonlinear reflection impedance, which comprises: S401, initialize a receiving end reactance guess value Then the initialized receiving end total impedance is: ; S402, calculating the initialized reflection impedance according to the double-coil mutual inductance model ; S403, solve total impedance by using initialized reflection impedance and construct system equation ; S404, extracting the receiving end voltage calculating the receiving current ; S405, updating the next step receiving end total impedance by using the receiving end voltage and the receiving end current ; S406, repeat steps S402-S405 until where x is the iteration count minus 1, is the total anti-convergence threshold.

10. A wireless charging optimization system, comprising: The wireless inductive power transmission circuit comprises: The transmitting end comprises: a direct current power supply Vd connected with a radio frequency choke L1 and an active switch S; the active switch S is connected with a capacitor C1 in parallel, the capacitor C1 is connected with an LC series resonance circuit in parallel, the LC series resonance circuit comprises a transmitting coil Coil1 and a resonance capacitor C2; The transmitting coil Coil1 is coupled with the receiving end; the receiving end comprises: a receiving coil Coil2 connected with a capacitor C3 and a charging circuit, the receiving coil Coil2 is coupled with the transmitting end; The transmitting end and the receiving end work according to the target design parameters, and realize the wireless charging optimization method of any one of claims 1-9.

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