MC-WPT system mutual inductance detection method and system based on frequency modulation and phase shift control

Abstract

The invention relates to the technical field of magnetic coupling wireless power transmission (MC-WPT), and particularly discloses an MC-WPT system mutual inductance detection method and system based on frequency modulation and phase shift control, when the system is not in a resonance state due to parameter drift, the power factor angle of a transmitting end is enabled to be in a preset range by adopting frequency modulation control, and the frequency modulation control is performed on the transmitting end; and enabling the phase angle of the receiving end to be 90 degrees by adopting phase shift control, enabling the system to resonate again, and calculating the mutual inductance between the coupling mechanisms according to the resonant frequency at the moment and the full-bridge fundamental wave output voltage of the transmitting end and the current of the resonant circuit of the receiving end or the full-bridge fundamental wave output voltage of the receiving end and the current of the resonant circuit of the transmitting end. Due to the introduction of frequency modulation control and phase shift control, the mutual inductance detection measurement can be very accurate. Experiments prove that the accuracy of the mutual inductance detected by using the method is relatively high.

Description

Technical Field

[0001] The present invention relates to the technical field of magnetically coupled wireless power transmission (MC-WPT), and in particular to a mutual inductance detection method and system for an MC-WPT system based on frequency modulation and phase shift control. Background Art

[0002] Due to its convenience and growing power transmission capacity, wireless power transmission systems are currently receiving widespread attention and application. However, during the operation of the equipment, a series of inevitable problems such as capacitance parameter drift or system parameter changes, or a series of problems caused by operating equipment errors may cause system damage or even collapse. Therefore, the importance of parameter identification in MC-WPT systems is self-evident. Among them, since mutual inductance is an important influencing parameter such as transmission power and transmission efficiency, the mutual inductance identification problem in MC-WPT systems has always been a research hotspot.

[0003] Some literature has proposed a black box strategy to detect faults in the system coupling mechanism. Although this method can obtain the approximate location of the fault, it cannot obtain accurate information about the fault, let alone identify mutual inductance. Some literature has proposed a sensitivity analysis method for selecting a mutual inductance identification model for wireless charging of electric vehicles. Although this method can identify mutual inductance, the mutual inductance calculated according to the reference formula is far from the mutual inductance of the actual system. Some literature has proposed a coupling coefficient identification method to achieve maximum power transmission in the WPT system through impedance matching. Although this method can detect the coupling coefficient k of the system, it cannot separate the mutual inductance under the drift of capacitance and inductance parameters.

[0004] It can be seen that the current literature cannot accurately detect the mutual inductance of the MC-WPT system under parameter drift. Summary of the invention

[0005] The present invention provides a mutual inductance detection method and system for an MC-WPT system based on frequency modulation and phase shift control, and solves the technical problem of how to accurately detect the mutual inductance of the MC-WPT system under parameter drift.

[0006] In order to solve the above technical problems, the present invention provides a mutual inductance detection method of a MC-WPT system based on frequency modulation and phase shift control, comprising the steps of:

[0007] A bidirectional MC-WPT system is constructed, which includes a primary side and a secondary side, the primary side includes a primary high-frequency inverter, and the secondary side includes a secondary high-frequency inverter; when transmitting electric energy from the primary side to the secondary side, the primary side acts as a transmitter, the primary high-frequency inverter acts as a transmitter high-frequency inverter, the secondary high-frequency inverter acts as a full-bridge rectifier, and the secondary side acts as a receiver; when transmitting electric energy from the secondary side to the primary side, the secondary side acts as a transmitter, the secondary high-frequency inverter acts as a transmitter high-frequency inverter, the primary high-frequency inverter acts as a full-bridge rectifier, and the primary side acts as a receiver;

[0008] Set the system parameters so that the natural angular frequency of the system is ω;

[0009] The key point is that the mutual inductance detection method further comprises the steps of:

[0010] Exciting the transmitting end with a natural angular frequency ω;

[0011] Detect whether the power factor angle of the transmitter is within the preset range. If so, continue to excite with the inherent angular frequency ω. If not, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ω f and controlling the phase angle of the receiving end to be 90° by phase shifting;

[0012] The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the transmitting end and the current of the resonant circuit of the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the receiving end and the current of the resonant circuit of the transmitting end.

[0013] Furthermore, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage of the transmitting end divided by the angular frequency ωf and then divided by the modulus of the current of the resonant circuit of the receiving end.

[0014] Furthermore, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the receiving end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant tank at the transmitting end.

[0015] Furthermore, the steps of detecting the power factor angle of the transmitting end are:

[0016] Sampling the current and voltage waveforms in the resonant tank of the transmitting end and multiplying the sampled current and voltage waveforms by an integrator and integrating them in one cycle to obtain active power P;

[0017] The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q;

[0018] Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

[0019] Furthermore, the preset range of the power factor angle of the transmitting end is [0°, 10°].

[0020] The present invention also provides a MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control, which is applied to the MC-WPT system mutual inductance detection method based on frequency modulation and phase shift control, and the key lies in: comprising a first sensor, a second sensor, and a controller connected to the first sensor and the second sensor, and the controller is also connected to the primary high-frequency inverter and the secondary high-frequency inverter;

[0021] The first sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity of the primary side and send them to the controller;

[0022] The second sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity on the secondary side and send them to the controller;

[0023] The controller is used to:

[0024] Exciting the transmitting end with a natural angular frequency ω;

[0025] Calculate whether the power factor angle of the transmitter is within a preset range. If so, continue to excite with the natural angular frequency ω. If not, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ωf, and the phase angle of the receiving end is 90° through phase shift control;

[0026] The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated based on the full-bridge fundamental wave output voltage of the transmitting end and the current of the resonant circuit of the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the receiving end and the current of the resonant circuit of the transmitting end.

[0027] In one embodiment, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the transmitting end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant circuit at the receiving end.

[0028] In another embodiment, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the receiving end divided by the angular frequency ω fThen divide it by the modulus of the current of the resonant tank at the transmitting end.

[0029] In one embodiment, the step of calculating the power factor angle of the transmitting end is:

[0030] According to the current and voltage waveforms in the resonant tank of the transmitting end, the sampled current and voltage waveforms are multiplied by an integrator and then integrated in one cycle to obtain active power P;

[0031] The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q;

[0032] Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

[0033] In one implementation, the preset range of the power factor angle of the transmitting end is [0°, 10°].

[0034] The MC-WPT system mutual inductance detection method and system based on frequency modulation and phase shift control provided by the present invention, when the system has parameter drift and is no longer in a resonant state, frequency modulation control is used to make the power factor angle of the transmitting end within a preset range, and phase shift control is used to make the phase angle of the receiving end at 90°, so that the system resonates again, and the mutual inductance between the coupling mechanisms is calculated based on the resonant frequency at this time and the full-bridge fundamental wave output voltage of the transmitting end, the current of the resonant circuit of the receiving end, or the full-bridge fundamental wave output voltage of the receiving end, and the current of the resonant circuit of the transmitting end. Due to the introduction of frequency modulation control and phase shift control, this mutual inductance detection measurement can be very accurate. Experiments have verified that the accuracy of the mutual inductance detected by the present invention is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a flow chart of a mutual inductance detection method of an MC-WPT system based on frequency modulation and phase shift control provided by an embodiment of the present invention;

[0036] Figure 2 It is a topology diagram of the bidirectional SS type MC-WPT system during forward transmission provided by an embodiment of the present invention;

[0037] Figure 3 is a parameter vector diagram in a resonant cavity provided by an embodiment of the present invention;

[0038] Figure 4 It is a structural diagram of a mutual inductance detection system of an MC-WPT system based on frequency modulation and phase shift control provided by an embodiment of the present invention;

[0039] Figure 5 is a diagram of mutual inductance detection results at the initial resonance provided by an embodiment of the present invention;

[0040] Figure 6is a diagram showing the frequency increment and primary power factor angle control result at the initial resonance provided by an embodiment of the present invention;

[0041] Figure 7 is a diagram of mutual inductance detection results during re-resonance provided by an embodiment of the present invention;

[0042] Figure 8 This is a diagram showing the frequency increment and primary power factor angle control result during re-resonance provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The following specifically illustrates the implementation mode of the present invention in conjunction with the accompanying drawings. The embodiments are provided for illustrative purposes only and cannot be understood as limiting the present invention. The accompanying drawings are provided for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention, because many changes can be made to the present invention without departing from the spirit and scope of the present invention.

[0044] The MC-WPT system mutual inductance detection method based on frequency modulation and phase shift control provided in the embodiment of the present invention is as follows: Figure 1 As shown, the steps include:

[0045] A bidirectional MC-WPT system is constructed, which includes a primary side and a secondary side, the primary side includes a primary high-frequency inverter, and the secondary side includes a secondary high-frequency inverter; when transmitting electric energy from the primary side to the secondary side, the primary side acts as a transmitter, the primary high-frequency inverter acts as a transmitter high-frequency inverter, the secondary high-frequency inverter acts as a full-bridge rectifier, and the secondary side acts as a receiver; when transmitting electric energy from the secondary side to the primary side, the secondary side acts as a transmitter, the secondary high-frequency inverter acts as a transmitter high-frequency inverter, the primary high-frequency inverter acts as a full-bridge rectifier, and the primary side acts as a receiver;

[0046] Set the system parameters so that the natural angular frequency of the system is ω;

[0047] Excite the transmitter with the natural angular frequency ω (the phase of the transmitter is always 0°, and the phase of the receiver is 90°. The power factor angle of the transmitter is 0-10°, and the power factor angle of the receiver is 180°);

[0048] Detect whether the power factor angle of the transmitter is within the preset range ([0°, 10°]). If so, continue to excite with the inherent angular frequency ω. Otherwise, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ω f And through phase shift control, the phase angle of the receiving end is made 90°;

[0049] The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage at the transmitting end and the current of the resonant circuit at the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage at the receiving end and the current of the resonant circuit at the transmitting end.

[0050] The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the transmitting end divided by the angular frequency ω f Then divided by the modulus of the current of the resonant circuit at the receiving end. Alternatively, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental wave output voltage at the receiving end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant tank at the transmitting end.

[0051] The steps to detect the power factor angle of the transmitter are:

[0052] Sampling the current and voltage waveforms in the resonant tank of the transmitting end and multiplying the sampled current and voltage waveforms by an integrator and integrating them in one cycle to obtain active power P;

[0053] The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q;

[0054] Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

[0055] The following takes the MC-WPT system as an example to explain the mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control in more detail.

[0056] Figure 2 The circuit topology diagram of a typical bidirectional SS-type MC-WPT system during forward transmission (from primary side to secondary side) is shown. The SS-type MC-WPT system includes a primary side and a secondary side. The primary side includes a DC power supply V connected in sequence. dc , primary high-frequency inverter (full-bridge inverter composed of switch tubes S1 to S4), primary series compensation capacitor C p and the primary coil L p (The current is I p The secondary side includes a secondary coil L connected in series. s (The current is I s Indicated), secondary series compensation capacitor C s , secondary high-frequency inverter (full-bridge inverter composed of switch tubes T1 to T4), filter capacitor C f and load resistance R L (The voltage is V out , that is, the system output voltage).

[0057] exist Figure 2 Middle,U p and U s Represent the fundamental output voltage of the primary and secondary full bridges respectively. Where:

[0058]

[0059] Among them, V dp represents the primary side DC input voltage, β p represents the phase shift angle in the primary inverter, V ds represents the secondary side DC output voltage, β s represents the phase shift angle in the secondary-side inverter, and δ represents the phase angle of the secondary-side rectified input voltage lagging the primary-side inverter output voltage.

[0060] The system satisfies equation (3) at all times, and when the system resonates, it satisfies equation (4):

[0061]

[0062] Where ω represents the operating angular frequency of the system.

[0063] When the system is resonant, the mutual inductance M is calculated by the following formula:

[0064]

[0065] Where ωf represents the angular frequency of the system when it resonates under frequency modulation control.

[0066] In the resonant state, the transmission power of the system is the largest, so if hard switching is not considered, most MC-WPT systems work in a fully resonant state. In this state, only the effective values ​​of the voltage and current parameters of the resonant tank circuit and the angular frequency in the resonant state are needed, such as formula (5), to calculate the two sets of mutual inductance. However, when the system parameters change, such as the temperature drift caused by the long-term operation of the capacitor or the change of the self-mutual inductance parameters caused by the coupling mechanism deviation, the system will not maintain the resonant state, so the system no longer satisfies formula (4). If formula (5) is still used to calculate the mutual inductance M, the calculated error may be very large. Therefore, in order to simplify the calculation process, this example takes some measures to make it return to the resonant state again. In engineering practice and experimental research, this example adopts frequency modulation control (FM control) to make the system return to the resonant state again.

[0067] When the system re-enters the resonant state through FM control, equation (5) is satisfied again, and the mutual inductance M can be recalculated by simple calculation. However, the working mechanism of FM control is to set the power factor angle to 0 or a small angle, because when the power factor angle is a small angle other than 0°, the resonant cavity exhibits weak inductance to reduce the peak voltage generated when the power tube is working, so as to reduce the current and voltage stress of the electrical components in actual production. Although this operation will sacrifice the sensitivity of mutual inductance detection, it is found through simulation that the detection accuracy is still very high, so this operation is very practical. When the power factor angle is 0°, the system is in a fully resonant state. At this time, the sensitivity of mutual inductance detection will be very high, but the current and voltage stress of the electrical components may be very large. Directly calculating the power factor angle by obtaining the detection results of the resonator voltage and the resonator current phase requires high precision of the detection device, which will increase the detection cost in the actual production process. Therefore, this example introduces the PQ algorithm (P represents active power and Q represents reactive power) to more simply calculate the power factor angle of the system.

[0068] In FM control, the power factor angle of the primary side is controlled to 0° or a smaller angle by changing the operating frequency of the primary side high-frequency inverter. After frequency modulation control, the secondary side phase angle is controlled to 180° through secondary side phase shift control to ensure that the system is in a resonant state. It should be noted that, from equation (4), when and When the phase between is 180°, if Then phase shift control can never be controlled and The phase difference between them is 90°. Similarly, frequency modulation control can never control and The phase difference between them is 0°, so the combined effect of FM control and phase shift control is to make as well as In other words, in this state, the resonant cavity is in a resonant state, and the relationship between the vectors in the resonant cavity is as follows: Figure 3 As shown, and The phase difference between them is 180°. and The phase difference between them is 0°. and The phase difference between them is 90°.

[0069] The PQ algorithm is to calculate the power factor angle through the active power P and reactive power Q of the system, instead of directly subtracting the voltage and current phase to obtain the power factor angle. The current and voltage waveforms in the resonant tank are obtained through the high-frequency sampling module, and the integrator integrates them in one cycle respectively, without directly subtracting the current and voltage phases. Because the detection of the phase angle requires high accuracy of the sampling module, the system introduces the PQ algorithm. The system introduces the PQ algorithm and FM control, and the power factor angle can be controlled by sampling the voltage and current information in the primary side resonant tank, as shown in equations (6) and (7), where θ refers to the power factor angle on the primary side.

[0070]

[0071] That is, the steps for detecting the power factor angle of the transmitting end are:

[0072] Sampling the current and voltage waveforms in the resonant tank of the transmitting end and integrating the sampled current and voltage waveforms in a period T to obtain active power P through an integrator;

[0073] The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q;

[0074] Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

[0075] The embodiment of the present invention further provides a MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control, which is applied to the MC-WPT system mutual inductance detection method based on frequency modulation and phase shift control, such as Figure 4 As shown, it includes a first sensor, a second sensor, and a controller connected to the first sensor and the second sensor, and the controller is also connected to a primary high-frequency inverter and a secondary high-frequency inverter;

[0076] The first sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity on the primary side and send them to the controller;

[0077] The second sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity on the secondary side and send them to the controller;

[0078] The controller is used to:

[0079] Exciting the transmitting end with a natural angular frequency ω;

[0080] Calculate whether the power factor angle of the transmitter is within the preset range. If so, continue to excite with the inherent angular frequency ω. If not, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ω f And through phase shift control, the phase angle of the receiving end is made 90°;

[0081] The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated based on the full-bridge fundamental wave output voltage at the transmitting end and the current of the resonant circuit at the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage at the receiving end and the current of the resonant circuit at the transmitting end.

[0082] In this example, a bidirectional SS type MC-WPT system is established in Matlab / Simulink. The parameters in the system resonant cavity are shown in Table 1.

[0083] Table 1 System parameters

[0084]

[0085] When the SS topology maintains resonance for the first time, the waveform of the parameter M calculated by the present invention is as follows: Figure 5 At the same time, this example can detect the result of FM control. The frequency increment waveform is as follows Figure 6 As shown in the figure, the yellow curve represents the power factor angle on the primary side, and the purple curve represents the frequency increment under frequency control. Figure 6 It can be seen that the frequency increment curve under FM control is initially oscillating. Since the system's natural resonant frequency is 85kHz, the maximum frequency increment accounts for a small proportion of the natural frequency, so the system can still maintain normal operation. Finally, the waveform quickly stabilized, and the frequency increment finally stabilized at around -735Hz. In order to reduce the peak voltage of the primary-side resonator voltage, the primary-side power factor angle is controlled to a small angle (set to 10° in this simulation) to make the primary-side resonator weakly inductive, which can make the charged capacitor discharge faster, thereby reducing or even eliminating the peak voltage. From the waveform curve in this example, it can be seen that the power factor angle finally stabilizes at 9.95°. Figure 5 and Figure 6 It can be seen that the control effects of the frequency modulation control and phase shift control of the present invention are relatively good. Through two samplings, the calculated mutual inductances are 64.32uH and 63.66uH respectively. Compared with the mutual inductance of 64uH set in the system in Table 1, the error is smaller and the accuracy is above 99%. It can be seen that the present invention has a higher accuracy in detecting mutual inductance.

[0086] Then, the capacitance value of the primary side resonant capacitor is changed to simulate the actual production process. p The capacitance value is controlled to be 1.3 times the capacitance value in the resonant state, so that the primary side resonator is no longer in the resonant state, and then the effects of frequency modulation control and phase shift control and the calculation results of mutual inductance under their control are observed. Figure 7 is the result of mutual inductance calculation, Figure 8is the control result of the power factor angle and frequency increment. Figure 7 It can be found that the sampling results of the two mutual inductance tests are 64.72uH and 64.29uH respectively. The power factor angle finally stabilizes at about 9.60°, and the frequency increment stabilizes at -456.1Hz. The detection result is very accurate and the control effect is also excellent.

[0087] In summary, the mutual inductance detection method and system of the MC-WPT system based on frequency modulation and phase shift control provided by the embodiment of the present invention, when the system has parameter drift and is no longer in a resonant state, frequency modulation control is used to make the power factor angle of the transmitting end within a preset range, and phase shift control is used to make the phase angle of the receiving end at 180°, so that the system resonates again, and the mutual inductance between the coupling mechanisms is calculated based on the resonant frequency at this time and the full-bridge fundamental wave output voltage of the transmitting end, the current of the resonant circuit of the receiving end, or the full-bridge fundamental wave output voltage of the receiving end, and the current of the resonant circuit of the transmitting end. Due to the introduction of frequency modulation control and phase shift control, this mutual inductance detection measurement can be very accurate. Experiments have verified that the accuracy of the mutual inductance detected by the present invention is high.

[0088] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be equivalent replacement methods and are included in the protection scope of the present invention.

Claims

1. A mutual inductance detection method for a MC-WPT system based on frequency modulation and phase shift control, comprising the steps of: A bidirectional MC-WPT system is constructed, which includes a primary side and a secondary side, the primary side includes a primary high-frequency inverter, and the secondary side includes a secondary high-frequency inverter; when transmitting electric energy from the primary side to the secondary side, the primary side acts as a transmitter, the primary high-frequency inverter acts as a transmitter high-frequency inverter, the secondary high-frequency inverter acts as a full-bridge rectifier, and the secondary side acts as a receiver; when transmitting electric energy from the secondary side to the primary side, the secondary side acts as a transmitter, the secondary high-frequency inverter acts as a transmitter high-frequency inverter, the primary high-frequency inverter acts as a full-bridge rectifier, and the primary side acts as a receiver; Set the system parameters so that the natural angular frequency of the system is ω; It is characterized in that The mutual inductance detection method also includes the steps of: Exciting the transmitting end with a natural angular frequency ω; Detect whether the power factor angle of the transmitter is within the preset range. If so, continue to excite with the inherent angular frequency ω. If not, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ω f and controlling the phase angle of the receiving end to be 90° by phase shifting; The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the transmitting end and the current of the resonant circuit of the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the receiving end and the current of the resonant circuit of the transmitting end.

2. The mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control according to claim 1 is characterized in that: The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental wave output voltage of the transmitting end divided by the angular frequency ωf and then divided by the modulus of the current of the resonant circuit of the receiving end.

3. The mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control according to claim 2 is characterized in that: The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the receiving end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant tank at the transmitting end.

4. The mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control according to claim 3 is characterized in that: The steps to detect the power factor angle of the transmitter are: Sampling the current and voltage waveforms in the resonant tank of the transmitting end and multiplying the sampled current and voltage waveforms by an integrator and integrating them in one cycle to obtain active power P; The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q; Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

5. The mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control according to claim 4 is characterized in that: The preset range of the power factor angle of the transmitter is [0°, 10°].

6. A MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control, applied to a MC-WPT system mutual inductance detection method based on frequency modulation and phase shift control as claimed in any one of claims 1 to 5, characterized in that: The invention comprises a first sensor, a second sensor, and a controller connected to the first sensor and the second sensor, wherein the controller is also connected to the primary high-frequency inverter and the secondary high-frequency inverter; The first sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity of the primary side and send them to the controller; The second sensor is used to detect the full-bridge fundamental wave output voltage and the current of the resonant cavity on the secondary side and send them to the controller; The controller is used to: Exciting the transmitting end with a natural angular frequency ω; Calculate whether the power factor angle of the transmitter is within the preset range. If so, continue to excite with the inherent angular frequency ω. If not, use frequency modulation control to change the excitation frequency of the transmitter so that the power factor angle of the transmitter is within the preset range. At this time, the system angular frequency is ω f and controlling the phase angle of the receiving end to be 90° by phase shifting; The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated based on the full-bridge fundamental wave output voltage of the transmitting end and the current of the resonant circuit of the receiving end; or, the mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is calculated by obtaining the full-bridge fundamental wave output voltage of the receiving end and the current of the resonant circuit of the transmitting end.

7. The MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control according to claim 6 is characterized in that: The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the transmitting end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant circuit at the receiving end.

8. The mutual inductance detection method of the MC-WPT system based on frequency modulation and phase shift control according to claim 7 is characterized in that: The mutual inductance between the coupling mechanisms of the bidirectional MC-WPT system is equal to the modulus of the full-bridge fundamental output voltage at the receiving end divided by the angular frequency ω f Then divide it by the modulus of the current of the resonant tank at the transmitting end.

9. The MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control according to claim 8 is characterized in that: The steps to calculate the power factor angle at the transmitter are: According to the current and voltage waveforms in the resonant tank of the transmitting end, the sampled current and voltage waveforms are multiplied by an integrator and then integrated in one cycle to obtain active power P; The voltage waveform is phase-shifted by 90° and then multiplied by the current waveform, and then integrated within one cycle to obtain the reactive power Q; Calculate the power factor angle at the transmitter equal to the inverse tangent (Q / P).

10. The MC-WPT system mutual inductance detection system based on frequency modulation and phase shift control according to claim 9, characterized in that: The preset range of the power factor angle of the transmitting end is [0°, 10°].

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