Wireless power supply system mutual inductance and load identification method based on direct current information detection

Abstract

The invention relates to a wireless power supply system mutual inductance and load identification method based on direct current information detection, and the method comprises the steps: constructing a series circuit model based on energy negative feedback WPT, and extracting the primary side data of the series circuit model; according to the primary side data, obtaining the total impedance of a real part and the total impedance of an imaginary part; and obtaining a mutual inductance value and a load resistance value based on the real part total impedance and the imaginary part total impedance. The coupling coefficient and the load can be estimated in real time by measuring the direct current component of the input current and the values of the input square wave voltage and the detuning correction voltage.

Description

Technical Field

[0001] The present invention relates to the technical field of dynamic parameter detection of wireless power transmission, and in particular to a mutual inductance and load identification method of a wireless power supply system based on direct current information detection. Background Art

[0002] Wireless Power Transfer (WPT) technology has gained widespread adoption due to its safety, reliability, and portability. In real-world power supply environments, unavoidable environmental factors, such as changes in coil distance, can cause random fluctuations in the coupling coefficient. Furthermore, temperature fluctuations can cause changes in the actual internal resistance of electronic components, affecting the system's transmission efficiency. Therefore, dynamic parameter monitoring of WPT systems is crucial for improving system stability and efficiency.

[0003] Traditional series-connected WPT circuit status detection primarily involves primary-side and secondary-side status detection. In secondary-side status detection, load voltage and current are obtained for dynamic detection. Existing solutions propose only detecting the load voltage and input voltage, and using an analytical expression for the input impedance to derive the relationship between mutual inductance and load, load voltage, and input voltage. However, this approach requires measuring not only the load voltage but also the primary-side input voltage. For smaller devices, such as medical electronics and mobile phone chargers, parameter estimation using only primary-side data has attracted increasing attention. Existing solutions estimate the coupling coefficient and resistive load based on primary-side information. These methods typically require the primary-side input voltage, input current, and the phase difference between them to achieve parameter estimation. While this measurement method provides a simple approach for WPT system parameter identification, measuring the phase difference between the input voltage and input current requires high-precision measurement equipment and algorithms, as well as the input current amplitude. At high frequencies, even subtle noise or interference can cause errors in the phase difference or amplitude measurements, affecting the accuracy of coupling coefficient and load estimation. Summary of the Invention

[0004] In order to solve the problems existing in the above-mentioned prior art, the purpose of the present invention is to provide a mutual inductance and load identification method for a wireless power supply system based on DC information detection, which only requires measuring the DC component of the input current and the values ​​of the input square wave voltage and the detuning correction voltage to estimate the coupling coefficient and load in real time.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A method for identifying mutual inductance and load of a wireless power supply system based on DC information detection includes:

[0007] Constructing a series circuit model based on WPT with negative energy feedback, and extracting primary side data of the series circuit model;

[0008] Obtaining a real total impedance and an imaginary total impedance according to the primary side data;

[0009] A mutual inductance value and a load resistance value are obtained based on the real total impedance and the imaginary total impedance.

[0010] Optionally, the series circuit model includes:

[0011] Primary side module, used to input DC power;

[0012] The secondary side module is used to receive the DC power and provide it to the load.

[0013] Optionally, the primary-side module includes: an input voltage source for providing a DC power supply, wherein the positive electrode of the input voltage source is connected to the gate of a first MOSFET, and the negative electrode of the input voltage source is connected to the drain of a second MOSFET. The drain of the first MOSFET is connected to a transmitting coil, a first capacitor, and a parasitic resistor. The transmitting coil and the first capacitor form a resonant network to maximize energy transmission efficiency and couple high-frequency alternating current. At the same time, the drain of the first MOSFET is further connected to the drain of a third MOSFET and the gate of a fourth MOSFET. The gate of the third MOSFET and the drain of the fourth MOSFET are connected to an energy storage capacitor. The energy storage capacitor is used to store reactive power. By adjusting the phase difference between the third MOSFET and the fourth MOSFET and the first MOSFET and the second MOSFET, the reactive power is converted into active power, forming a new dynamic relationship with the input voltage, eliminating the imaginary part of the circuit, and achieving self-resonance.

[0014] Optionally, the secondary side module includes: a receiving coil for receiving the high-frequency alternating current, one end of the receiving coil is connected to a resonant capacitor and a parasitic resistor, the receiving coil and the resonant capacitor form a parallel resonant circuit, matching the transmitting frequency for resonance enhancement, the other end of the receiving coil is connected to the anode of the second full-bridge rectifier and the cathode of the fourth full-bridge rectifier, the other side of the resonant capacitor is connected to the anode of the first full-bridge rectifier and the cathode of the third full-bridge rectifier, the cathode of the first full-bridge rectifier is connected to the cathode of the third full-bridge rectifier, the anode of the second full-bridge rectifier is connected to the anode of the fourth full-bridge rectifier, the anode of the first full-bridge rectifier and the cathode of the second full-bridge rectifier are also connected to one end of the filter capacitor, the other end of the filter capacitor is connected to the anode of the third full-bridge rectifier and the anode of the fourth full-bridge rectifier, for converting the received alternating current into direct current and providing it to the load, and the two ends of the filter capacitor are also connected to the two ends of the load.

[0015] Optionally, the primary side data includes: an input square wave voltage V1, a detuning correction voltage V2 and a DC component of an input current.

[0016] Optionally, obtaining the real total impedance includes:

[0017]

[0018] Among them, R in is the real part of the total impedance, R S1 is the stray resistance on the primary coil, ω is the angular frequency, M is the mutual inductance between the transmitting coil and the receiving coil, R L is the load, R S11 is the stray resistance on the secondary coil, L S is the receiving coil, C S is the resonant capacitor.

[0019] Optionally, obtaining the imaginary total impedance includes:

[0020]

[0021] Among them, X in is the total imaginary impedance, ω is the angular frequency, L1 is the transmitting coil, C1 is the first capacitor, R L is the load, R S11 is the stray resistance on the secondary coil, M is the mutual inductance between the transmitting coil and the receiving coil, L S is the receiving coil, C S is the resonant capacitor.

[0022] Optionally, obtaining the mutual inductance value includes:

[0023]

[0024] Where M is the mutual inductance between the transmitting coil and the receiving coil, ω is the angular frequency, and V fa is the fundamental component of V1, V i1 is a DC voltage source, i o is the DC component of the input current, R s1 is the stray resistance on the primary coil, R L is the load, L s is the receiving coil, C S is the resonant capacitor.

[0025] Optionally, obtaining the load resistance value includes:

[0026]

[0027] Among them, R L is the load resistance value, R S1 is the stray resistance on the primary coil, ω is the angular frequency, L s is the receiving coil, C s is the resonant capacitor, R s11 is the stray resistance on the secondary coil, V fa is the fundamental component of V1, V i1 is a DC voltage source, i o is the DC component of the input current, L1 is the transmitting coil, L s is the receiving coil, C s is the resonant capacitor, V2 is the detuning correction voltage, and V1 is the input square wave voltage.

[0028] The beneficial effects of the present invention are:

[0029] The present invention provides a simple measurement method based on the energy negative feedback WPT network. By simply measuring the DC value of the square waves V1 and V2 and the input current, the relationship between the load impedance and mutual inductance and other parameters can be obtained. During simulation, the actual value calculated by measuring the DC value is consistent with the theoretical value of the circuit design, with a small error.

[0030] The detection scheme of the present invention is simplified and efficient, and can achieve precise control of key parameters of the wireless power transmission system through primary-side DC data, significantly improving the design flexibility and practicality of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 This is a flow chart of a method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to an embodiment of the present invention;

[0033] Figure 2 This is a WPT series-series circuit diagram based on energy negative feedback in an embodiment of the present invention. DETAILED DESCRIPTION

[0034] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0035] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1 As shown, this embodiment discloses a method for identifying mutual inductance and load of a wireless power supply system based on DC information detection, including: constructing a series circuit model based on energy negative feedback WPT, extracting primary side data of the series circuit model; obtaining the real total impedance and the imaginary total impedance based on the primary side data; and obtaining the mutual inductance value and the load resistance value based on the real total impedance and the imaginary total impedance.

[0037] like Figure 2 As shown in the figure, based on the energy negative feedback WPT series-series circuit diagram, the key formula for realizing energy negative feedback is as follows:

[0038]

[0039]

[0040] Among them, P in is the input power, V i1 is a DC voltage source, V fa1 is the fundamental component of V1, i ois the DC component of the input current i1, which can be obtained by Fourier transformation. S1 and S2 are half-bridge inverters composed of MOSFETs, L1 is the primary coil, L2 is the secondary coil, C1 and C s is the compensation capacitor, C i2 For large energy storage capacitors, R S1 and R S11 is the stray resistance on the coil, M is the mutual inductance between L1 and Ls, f is the operating frequency, ω is the angular frequency, k is the coupling coefficient, R L is the load. According to the mutual inductance theory, the receiver can be regarded as an equivalent impedance Z eq , the total impedance is Z in , where R in Z in The real part, X in Z in The imaginary part of .

[0041] Furthermore, the series circuit model includes:

[0042] Primary side module, used to input DC power;

[0043] The secondary side module is used to receive DC power and provide it to the load.

[0044] Furthermore, the primary side module includes: an input voltage source for providing a DC power supply, the positive electrode of the input voltage source is connected to the gate of the first MOSFET, the negative electrode of the input voltage source is connected to the drain of the second MOSFET, the drain of the first MOSFET is connected to the transmitting coil, the first capacitor and the parasitic resistance, and the transmitting coil and the first capacitor form a resonant network to maximize energy transmission efficiency and couple high-frequency alternating current. At the same time, the drain of the first MOSFET is further connected to the drain of the third MOSFET and the gate of the fourth MOSFET, the gate of the third MOSFET and the drain of the fourth MOSFET are connected to the energy storage capacitor, and the energy storage capacitor is used to store reactive power. By adjusting the phase difference between the third MOSFET and the fourth MOSFET and the first MOSFET and the second MOSFET, the reactive power is converted into active power, forming a new dynamic relationship with the input voltage, eliminating the imaginary part of the circuit, and achieving self-resonance.

[0045] Furthermore, the secondary side module includes: a receiving coil for receiving high-frequency alternating current, one end of the receiving coil is connected to a resonant capacitor and a parasitic resistor, the receiving coil and the resonant capacitor form a parallel resonant circuit, matching the transmitting frequency for resonance enhancement, the other end of the receiving coil is connected to the anode of the second full-bridge rectifier and the cathode of the fourth full-bridge rectifier, the other side of the resonant capacitor is connected to the anode of the first full-bridge rectifier and the cathode of the third full-bridge rectifier, the cathode of the first full-bridge rectifier is connected to the cathode of the third full-bridge rectifier, the anode of the second full-bridge rectifier is connected to the anode of the fourth full-bridge rectifier, the anode of the first full-bridge rectifier and the cathode of the second full-bridge rectifier are also connected to one end of the filter capacitor, the other end of the filter capacitor is connected to the anode of the third full-bridge rectifier and the anode of the fourth full-bridge rectifier, for converting the received alternating current into direct current and providing it to the load, and the two ends of the filter capacitor are also connected to the two ends of the load.

[0046] Specifically, this example provides a series-series WPT resonant network system based on energy negative feedback, including an input voltage source, a half-bridge inverter, a full-bridge rectifier, a coil, a resonant capacitor, a parasitic resistor, a rectifier capacitor, an energy storage capacitor, and an actual load. i1 Provides the DC power required by the system, wherein the half-bridge inverter includes a first half-bridge inverter and a second half-bridge rectifier. The first half-bridge rectifier consists of a first MOSFET S1 and a second MOSFET S2, and the second half-bridge rectifier consists of a third MOSFET S3 and a fourth MOSFET S4. By controlling the half-bridge inverter composed of MOSFETs S1 and S2, DC power is converted into a high-frequency AC signal. The coil includes a transmitting coil L1 and a receiving coil L s The resonant capacitor includes the transmitting end and the receiving end resonant capacitor. The high frequency AC is coupled by the transmitting coil L1 and transmitted to the receiving coil L s The transmitting coil and the resonant capacitor C1 form a resonant network to maximize the energy transmission efficiency. s with C s A parallel resonant circuit is formed to match the transmission frequency to achieve resonance enhancement. At the same time, the received AC power is converted into DC through the full-bridge rectifier (composed of D1-D4) for use by the load R. The energy storage capacitor C i2 It is used to store reactive power and convert reactive power into active power by adjusting the phase difference between S3 and S4 and the first half-bridge rectifier. At this time, the voltage across it gradually increases and is consistent with the original input voltage V i1 A new dynamic relationship is formed, and the imaginary part of the circuit is eliminated to achieve the function of autonomous resonance. The relationship between autonomous resonance v1 and v2 is used to estimate DC parameters. o Complete the stable output of energy.

[0047] From left to right, the transmitter is the input voltage source Vi1 , consisting of half-bridge inverter MOSFET tubes S1 and S2, transmitting coil L1, transmitting end resonant capacitor C1, parasitic resistance R s1 ; MOSFET tubes S3, S4, energy storage capacitor C i2 The receiving end is the receiving coil L s , resonant capacitor C s , parasitic resistance R s11 , full-bridge rectifier, rectifier capacitor C o , load resistance R.

[0048] The positive electrode of the input voltage source is connected to the gate of the first MOSFET S1, and the negative electrode is connected to the drain of the second MOSFET S2. i2 They are respectively connected to the gate of the third MOSFET S3 and the drain of the fourth MOSFET S4.

[0049] Input voltage source V i1 The positive electrode is connected to the gate of S1, and the negative electrode is connected to the drain of S2. The drain of S1 is connected to the transmitting coil L1, capacitor C1 and parasitic resistor R s1 connected to the drain of S3 and the gate of S4, the energy storage capacitor C i2 Connected to the gate of S3 and the drain of S4 respectively.

[0050] Receiving end coil L s One end and the resonant capacitor C S and the parasitic resistance R s11 The other end of the resonant capacitor is connected to the anode of D2 and the cathode of D4. The other side of the resonant capacitor is connected to the anode of D1 and the cathode of D3. In a full-bridge rectifier circuit, the cathode of D1 is connected to the cathode of D3, and the anode of D2 is connected to the anode of D4. One end of the filter capacitor C0 is connected to the anode of D1 and the cathode of D2, and the other end is connected to the anode of D3 and the anode of D4. The actual load R is connected to both ends of the filter capacitor C0.

[0051] Except for the coupling coefficient and actual load, the other circuit parameters are known. By measuring the DC value i of the square waves V1, V2 and the input current i1 o The actual values ​​of mutual inductance and load resistance can be calculated, thereby achieving the purpose of dynamically detecting WPT mutual inductance and load resistance based on DC information.

[0052] Furthermore, the primary side data includes: input square wave voltage V1, detuning correction voltage V2 and DC component of input current.

[0053] Furthermore, the total impedance Z of the series-series WPT circuit is in By measuring the known quantities V1, V2, i oTo measure the real impedance R in , the imaginary total impedance X is derived from the relationship between V1 and V2 in , thus deriving the relationship between load impedance and mutual inductance and other measurement parameters. Mutual inductance M will fluctuate significantly due to changes in the relative position of the receiving coil and the transmitting coil (such as offset, angular misalignment); equivalent load resistance R L Typically, it dynamically adjusts with ambient temperature, affecting the distribution of system current and voltage. Therefore, real-time estimation of mutual inductance and equivalent load resistance can reflect the health of the current energy transmission channel, providing key input for efficient and safe charging control. During DC detection, real-time parameter detection of the system's mutual inductance and load can be achieved simply by detecting primary-side DC information. This detection method is more cost-effective and efficient than parameter detection using traditional bilateral communication.

[0054] Furthermore, obtaining the real total impedance includes:

[0055]

[0056] Among them, R in is the real part of the total impedance, R S1 is the stray resistance on the primary coil, ω is the angular frequency, M is the mutual inductance between the transmitting coil and the receiving coil, R L is the load, R S11 is the stray resistance on the secondary coil, L S is the receiving coil, C S is the resonant capacitor.

[0057] Furthermore, obtaining the imaginary total impedance includes:

[0058]

[0059] Among them, X in is the total imaginary impedance, ω is the angular frequency, L1 is the transmitting coil, C1 is the first capacitor, R L is the load, R S11 is the stray resistance on the secondary coil, M is the mutual inductance between the transmitting coil and the receiving coil, L S is the receiving coil, C S is the resonant capacitor.

[0060] Furthermore, obtaining the mutual inductance value includes:

[0061]

[0062] Where M is the mutual inductance between the transmitting coil and the receiving coil, ω is the angular frequency, and V fa is the fundamental component of V1, V i1 is a DC voltage source, io is the DC component of the input current, R s1 is the stray resistance on the primary coil, R L is the load, L s is the receiving coil, C S is the resonant capacitor.

[0063] Furthermore, obtaining the load resistance value includes:

[0064]

[0065] Among them, R L is the load resistance value, R S1 is the stray resistance on the primary coil, ω is the angular frequency, L s is the receiving coil, C s is the resonant capacitor, R s11 is the stray resistance on the secondary coil, V fa is the fundamental component of V1, V i1 is a DC voltage source, i o is the DC component of the input current, L1 is the transmitting coil, L s is the receiving coil, C s is the resonant capacitor, V2 is the detuning correction voltage, and V1 is the input square wave voltage.

[0066] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for identifying mutual inductance and load of a wireless power supply system based on DC information detection, characterized in that: include: Constructing a series circuit model based on WPT with negative energy feedback, and extracting primary side data of the series circuit model; Obtaining a real total impedance and an imaginary total impedance according to the primary side data; A mutual inductance value and a load resistance value are obtained based on the real total impedance and the imaginary total impedance.

2. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: The series circuit model includes: Primary side module, used to input DC power; The secondary side module is used to receive the DC power and provide it to the load.

3. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 2, characterized in that: The primary-side module includes: an input voltage source for providing a DC power supply, a positive electrode of the input voltage source connected to the gate of a first MOSFET, a negative electrode of the input voltage source connected to the drain of a second MOSFET, the drain of the first MOSFET connected to a transmitting coil, a first capacitor, and a parasitic resistor, the transmitting coil and the first capacitor forming a resonant network for maximizing energy transmission efficiency and coupling high-frequency AC power, the drain of the first MOSFET further connected to the drain of a third MOSFET and the gate of a fourth MOSFET, the gate of the third MOSFET and the drain of the fourth MOSFET connected to an energy storage capacitor, the energy storage capacitor for storing reactive power, and converting reactive power into active power by adjusting the phase difference between the third MOSFET and the fourth MOSFET and the first MOSFET and the second MOSFET, thereby forming a new dynamic relationship with the input voltage and eliminating the imaginary part of the circuit to achieve self-resonance.

4. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 3, characterized in that: The secondary side module includes: a receiving coil for receiving the high-frequency alternating current, one end of the receiving coil is connected to a resonant capacitor and a parasitic resistor, the receiving coil and the resonant capacitor form a parallel resonant circuit, matching the transmission frequency for resonance enhancement, the other end of the receiving coil is connected to the anode of the second full-bridge rectifier and the cathode of the fourth full-bridge rectifier, the other side of the resonant capacitor is connected to the anode of the first full-bridge rectifier and the cathode of the third full-bridge rectifier, the cathode of the first full-bridge rectifier is connected to the cathode of the third full-bridge rectifier, the anode of the second full-bridge rectifier is connected to the anode of the fourth full-bridge rectifier, the anode of the first full-bridge rectifier and the cathode of the second full-bridge rectifier are also connected to one end of a filter capacitor, the other end of the filter capacitor is connected to the anode of the third full-bridge rectifier and the anode of the fourth full-bridge rectifier, for converting the received alternating current into direct current and providing it to the load, and the two ends of the filter capacitor are also connected to the two ends of the load.

5. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: The primary side data includes: input square wave voltage V1, detuning correction voltage V2 and DC component i of input current o .

6. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: Obtaining the real total impedance includes: Among them, R in is the real part of the total impedance, R S1 is the stray resistance on the primary coil, ω is the angular frequency, M is the mutual inductance between the transmitting coil and the receiving coil, R L is the load, R S11 is the stray resistance on the secondary coil, L S is the receiving coil, C S is the resonant capacitor.

7. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: Obtaining the imaginary total impedance includes: Among them, X in is the total imaginary impedance, ω is the angular frequency, L1 is the transmitting coil, C1 is the first capacitor, R L is the load, R S11 is the stray resistance on the secondary coil, M is the mutual inductance between the transmitting coil and the receiving coil, L S is the receiving coil, C S is the resonant capacitor.

8. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: Obtaining the mutual inductance value includes: Where M is the mutual inductance between the transmitting coil and the receiving coil, ω is the angular frequency, and V fa is the fundamental component of V1, V i1 is a DC voltage source, i o is the DC component of the input current, R s1 is the stray resistance on the primary coil, R L is the load, L s is the receiving coil, C S is the resonant capacitor.

9. The method for identifying mutual inductance and load of a wireless power supply system based on DC information detection according to claim 1, characterized in that: Obtaining the load resistance value includes: Among them, R L is the load resistance value, R S1 is the stray resistance on the primary coil, ω is the angular frequency, L s is the receiving coil, C s is the resonant capacitor, R s11 is the stray resistance on the secondary coil, V fa is the fundamental component of V1, V i1 is a DC voltage source, l o is the DC component of the input current, L1 is the transmitting coil, L s is the receiving coil, C s is the resonant capacitor, V2 is the detuning correction voltage, and V1 is the input square wave voltage.

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