A hybrid coupled wireless power transmission system mutual inductance and mutual capacitance parameter identification method

Abstract

This invention discloses a method for identifying mutual inductance and mutual capacitance parameters in a hybrid-coupled wireless power transfer system, applicable to wireless power transfer systems where inductive and capacitive coupling coexist. Under the condition of a fixed system operating frequency, this method acquires time-domain signals such as primary-side voltage, primary-side current, and primary-side coil terminal voltage. A steady-state interval is selected, and the fundamental phasor is extracted using the synchronous integration method. Combined with known parameters such as compensation capacitor, coil self-inductance, and parasitic resistance of the compensation capacitor and coil, a system of complex equations including mutual inductance and mutual capacitance is established and solved to obtain the target parameters. Compared with existing methods that require changing the frequency or adding additional measurement circuits, this invention only requires a small number of voltage and current measurements to complete the identification of mutual inductance and mutual capacitance. The steps are simple, the implementation cost is low, and effective identification can still be achieved through the fundamental phasor even in the presence of inverter / rectifier nonlinear excitation.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically a method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system. Background Technology

[0002] Wireless power transfer technology, due to its advantages such as non-contact operation, insulation safety, and strong environmental adaptability, has broad application prospects in underwater power supply, mobile equipment charging, power supply for enclosed equipment, and energy transmission in special environments. Existing wireless power transfer systems mainly include three types: magnetic coupling, electric field coupling, and hybrid magneto-electric coupling. Among them, hybrid coupling wireless power transfer systems utilize both magnetic and electric field coupling to achieve energy transfer, possessing both strong anti-misalignment capability and high power density, and therefore attracting increasing attention.

[0003] In a hybrid coupled wireless power transfer system, the mutual inductance M H and mutual compatibility C H Mutual inductance M is a key parameter that determines the system's coupling strength, power transmission capability, resonant matching state, and control performance. When the relative position between the transmitter and receiver, the transmission distance, the alignment state, or the environmental medium changes, the mutual inductance M... H and mutual compatibility C H These will change accordingly, leading to fluctuations in system output power and transmission efficiency. Therefore, accurate identification of mutual inductance and mutual capacitance is of great significance for system modeling, adaptive parameter control, and performance optimization.

[0004] Existing parameter identification methods typically include frequency scanning, variable load, injected test signal, and small-signal model identification. These methods generally suffer from drawbacks such as requiring changes to the system's operating frequency, affecting normal system operation, necessitating additional test circuits or excitation signals, and high hardware complexity.

[0005] Especially in practical hybrid coupled wireless power transmission systems, the receiving side usually includes a rectifier bridge and a load resistor, and the system as a whole exhibits obvious nonlinear characteristics, making it difficult to directly apply traditional linear identification methods based on ideal sinusoidal steady state.

[0006] Therefore, there is an urgent need for a method to identify mutual inductance and mutual capacitance parameters in hybrid coupled wireless power transmission systems that can operate normally without changing the system's operating frequency or adding additional test signals, and that is applicable to systems containing nonlinear rectifier structures and considering the effects of parasitic resistance. Summary of the Invention

[0007] The purpose of this invention is to provide a method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system. This method can identify mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system that includes a nonlinear rectifier structure and considers the effects of parasitic resistance, without changing the system's operating frequency or adding additional test signals, and is applicable to such systems.

[0008] To achieve the above objectives, the present invention provides a method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system. The hybrid coupled wireless power transmission system includes a DC power supply, a high-frequency inverter, a primary-side compensation network, a rectifier load module, and a sampling and calculation module; wherein the hybrid coupling structure also includes the primary-side coil self-inductance L... P Secondary coil self-inductance L S Magnetic coupling mutual inductance M H Mutual capacitance C with electric field coupling H The rectifier load module has a non-linear structure, including a rectifier bridge and a load resistor.

[0009] The method includes the following steps:

[0010] S1, at the system operating frequency f d Under fixed operating conditions, the sampling and calculation module collects the primary inverter output voltage u1(t), primary output current i1(t), and primary coil terminal voltage u1(t). Lp (t);

[0011] S2. Select a steady-state integer period interval [t1, t2] from the acquired signal, and use the synchronous integration method to analyze u1(t), i1(t), and u... Lp (t) The fundamental frequency is extracted to obtain the operating frequency f. d The fundamental complex phasors U1, I1 and U are below Lp ;

[0012] S3. Based on the circuit topology of the primary-side compensation network, considering the parasitic resistance R of the primary-side compensation capacitor. C1 R Cp and the parasitic resistance R of the primary coil p In the case of the fundamental complex vector obtained in step S2, the equivalent node voltage vector U on the primary side is constructed. Cp , Coupling capacitor branch current phasor I CH and mutual inductance voltage phasor ΔU L ;

[0013] S4, Establish a system containing unknown mutual inductance M H Mutual compatibility with the unknown C H The complex coupling equations are obtained by separating the real and imaginary parts of the complex coupling equations to form a system of equations, and solving them yields the mutual inductance M.H With mutual compatibility C H The value.

[0014] As a further aspect of the present invention: the method of synchronous integration for fundamental frequency extraction of the signal in step S2 specifically includes:

[0015] Within the steady-state integer period interval [t1, t2], the time-domain signal x(t) to be extracted is compared with the fundamental reference complex exponential signal. By multiplying and integrating, the fundamental complex phasor of the signal at the operating frequency is obtained. Its expression is:

[0016]

[0017] In the formula, This refers to the system's operating angular frequency;

[0018] The time length of the steady-state integer periodic interval [t1, t2] satisfy T d The system's operating cycle is N, where N is a positive integer.

[0019] The fundamental effective value and phase angle of the corresponding signal can be obtained from the fundamental complex phasor, and its expression is:

[0020]

[0021]

[0022] In the formula: For signal The fundamental effective value; For fundamental complex phasor The phase angle.

[0023] As a further aspect of the present invention: the positive integer N in step S2 is ≥5; preferably, N consecutive complete cycles at the end of the data acquisition are selected for integration, where N≥10.

[0024] As a further aspect of the present invention: in step S3, the primary-side equivalent node voltage phasor U Cp , Coupling capacitor branch current phasor I CH Mutual inductance voltage phasor ΔU L They respectively satisfy:

[0025]

[0026]

[0027]

[0028] In the formula, U1 represents the fundamental complex phasor of the primary-side inverter output voltage, I1 represents the fundamental complex phasor of the primary-side output current, and U Lp C represents the fundamental complex phasor of the primary winding terminal voltage. t1 Indicates the primary-side compensation capacitor; C p This indicates the primary side compensation capacitor.

[0029] As a further aspect of the present invention: the step S4 involves an unknown mutual inductance M. H Mutual compatibility with the unknown C H The complex coupling equations satisfy:

[0030]

[0031] Take the real and imaginary parts of the complex coupling equation to form two real equations, and solve for the mutual inductance M. H With mutual compatibility C H .

[0032] As a further aspect of the present invention: before the fundamental frequency extraction in step S2, a preprocessing step is included: processing the voltage u1(t), current i1(t), and voltage u in the steady-state region. Lp (t) The signal is processed to remove the DC component, eliminating the DC bias caused by the switching action of the high-frequency inverter and the nonlinearity of the rectifier load; after obtaining the fundamental complex phasor, the parameter identification calculation of subsequent steps S3 to S4 is performed using the fundamental equivalent model.

[0033] As a further aspect of the present invention: the high-frequency inverter has a nonlinear structure, and the output voltage of the high-frequency inverter is a square wave excitation signal.

[0034] A hybrid coupled wireless power transmission system includes an execution module for the mutual inductance and mutual capacitance parameter identification method described in any of the above claims, wherein the execution module is configured to execute steps S1 to S4 to achieve online parameter identification.

[0035] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention provides a method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system. This method acquires the primary-side inverter output voltage, primary-side output current, and primary-side coil terminal voltage, extracts the fundamental complex phasor at the operating frequency, and establishes the mutual inductance and mutual capacitance coupling equations using a complex equivalent model including parasitic parameters, thereby realizing the mutual inductance M... H With mutual compatibility C HSynchronous identification. Compared with the prior art, the present invention has the following advantages: no need to change the system operating frequency; no need for additional test signals and additional measurement circuits; able to achieve synchronous identification of mutual inductance and mutual capacitance; applicable to nonlinear systems containing inverters and rectifiers; considering the influence of parasitic parameters, the identification accuracy is high; the method flow is clear, easy to implement, and has good engineering application value. Attached Figure Description

[0036] Figure 1 This is a schematic diagram of the system structure of the present invention.

[0037] Figure 2 This is the equivalent circuit diagram of the present invention.

[0038] Figure 3 This is a flowchart of the parameter identification process of the present invention.

[0039] Figure 4 This is a diagram showing the relationship between the equivalent mutual inductance and mutual capacitance between the coupled structures of the system of the present invention as a function of the distance between the coupled structures.

[0040] In the diagram: 1. DC power supply, 2. High-frequency inverter, 3. Primary side compensation network, 4. Hybrid coupling unit, 5. Secondary side compensation network, 6. Rectifier load module, 7. Sampling and calculation module. Detailed Implementation

[0041] The invention will now be further described with reference to the accompanying drawings.

[0042] Step 1: Construct the circuit topology diagram of the hybrid coupled wireless power transfer system.

[0043] refer to Figure 1 The circuit topology diagram of the hybrid coupled wireless power transfer system shown is shown. The system specifically includes: DC power supply 1, high-frequency inverter 2, primary side compensation network 3, hybrid coupling unit 4, secondary side compensation network 5, rectifier load module 6, and sampling and calculation module 7.

[0044] The DC power supply 1 is connected to the input terminal of the high-frequency inverter 2. The output terminal of the high-frequency inverter 2 is connected to the input terminal of the primary-side compensation network 3. The output terminal of the primary-side compensation network 3 is connected to the input terminal of the hybrid coupling unit 4. The output terminal of the hybrid coupling unit 4 is connected to the input terminal of the secondary-side compensation network 5. The output terminal of the secondary-side compensation network 5 is connected to the input terminal of the rectifier load module 6. The input ports of the sampling and calculation module 7 are respectively connected to the output terminal of the high-frequency inverter 2, the primary-side output current measurement branch, and both ends of the primary-side coil. The output terminal is used to perform fundamental phasor extraction and parameter solving.

[0045] The hybrid coupling structure 4 also includes magnetically coupled mutual inductance M. H Mutual capacitance C with electric field couplingH The rectifier load module 6 has a non-linear structure, including a rectifier bridge and a load resistor; the primary-side compensation network 3 includes at least a primary-side compensation capacitor C. t1 C p The primary winding, in which the compensation capacitor C t1 C p The parasitic resistances are R and R respectively. C1 R Cp Primary coil L p The parasitic resistance is R p .

[0046] In this embodiment, the system's DC input voltage V DC The voltage is 300V, and the system operating frequency is f. d The high-frequency inverter 2, operating at 800kHz, employs a single-phase full-bridge inverter circuit. The rectifier load module 6 uses a single-phase full-bridge rectifier circuit, and the rectified load is connected to a purely resistive load with a resistance R of 60Ω. The hybrid coupling unit 4 includes both magnetic coupling mutual inductance and electric field coupling mutual capacitance, wherein a preset real mutual inductance M is used. true With true compatibility C true The values ​​were 10.807 µH and 16.692 pF, respectively.

[0047] Step 2: Fix the system operating frequency, determine the known parameters and parasitic parameters of the system, and establish the complex equivalent model required for parameter identification; the specific method is as follows:

[0048] Step 2.1, determine the parameters of the primary and secondary coils;

[0049] In this embodiment, the self-inductance L of the primary coil P With the self-inductance L of the secondary coil S Both are 107µH, and the parasitic resistance R of the primary coil is 107µH. p Parasitic resistance R of the secondary coil S It is 100mΩ.

[0050] Step 2.2, determine the compensation network parameters;

[0051] In this embodiment, the compensation capacitor C t1 C t2 Both are 836.7 pF, C p C S All are 650.6pF, and the parasitic resistance of the compensation capacitors is 50mΩ.

[0052] Step 2.3: Establish the complex equivalent model of the system.

[0053] In this embodiment, the system operates under the conditions of high-frequency inverter square wave excitation and rectified nonlinear load. During parameter identification, the fundamental complex phasor at the operating frequency is extracted from the system voltage and current signals, and a fundamental equivalent model is used for complex equivalent modeling. The parameters of the primary-side compensation network, parasitic resistance branch, and hybrid coupling unit are as described above.

[0054] Step 3: Acquire the steady-state signal of the system and extract the fundamental phasor at the operating frequency; the specific method is as follows:

[0055] Step 3.1: Establish the hybrid coupled wireless power transfer system model in the MATLAB / Simulink simulation platform. After the system enters a stable operating state, acquire the primary side inverter output voltage signal u1(t), the primary side output current signal i1(t), and the primary side coil terminal voltage signal u. Lp (t);

[0056] Step 3.2: Select the steady-state integer period interval and perform DC removal processing.

[0057] A continuous integer number of complete working cycles are selected from the end of the acquired time-domain signal as the steady-state integration interval, and the signal within the interval is processed to remove the DC component, so as to reduce the influence of rectification nonlinearity and switching harmonics on the extraction of the fundamental phasor.

[0058] Step 3.3: Extract the fundamental complex phasor at the operating frequency.

[0059] The fundamental complex phasor of the signal at the operating frequency is extracted using the synchronous integration method, thereby obtaining the fundamental phasor U1 of the primary side inverter output voltage, the fundamental phasor I1 of the primary side input current, and the fundamental phasor U of the primary side coil voltage. Lp .

[0060] In this embodiment, the extraction result is: U1 V. A, V.

[0061] Step 4: Construct intermediate quantities and establish complex coupling equations that include mutual inductance and mutual compatibility; the specific method is as follows:

[0062] Step 4.1: Based on the primary side loop voltage relationship, construct the primary side equivalent node voltage phasor U. Cp Its expression is:

[0063]

[0064] In the formula, U1 represents the fundamental complex phasor of the primary-side inverter output voltage, I1 represents the fundamental complex phasor of the primary-side output current, and U Lp C represents the fundamental complex phasor of the primary winding terminal voltage.t1 R represents the primary side compensation capacitor. C1 This represents the parasitic resistance of the compensation capacitor.

[0065] Step 4.2, consider the primary-side compensation capacitor C p and its parasitic resistance R Cp Construct its equivalent admittance:

[0066]

[0067] Furthermore, the coupling capacitor branch current phasor I CH satisfy:

[0068]

[0069] In the formula, C p R represents the primary side compensation capacitor. Cp This indicates its series parasitic resistance.

[0070] Step 4.3, consider the parasitic resistance R of the primary coil. p Construct the mutual inductance voltage phasor ΔU L Its expression is:

[0071]

[0072] In the formula, L P R represents the self-inductance of the primary coil. p This represents the parasitic resistance of the primary coil.

[0073] Step 4.4, consider the secondary-side compensation capacitor C S and its parasitic resistance R CS Construct the equivalent admittance of the secondary-side compensation capacitor branch:

[0074]

[0075] Step 4.5: Based on the relationship between the mutual capacitance branch and the secondary side branch in the hybrid coupling unit, construct a system containing mutual inductance M. H With mutual compatibility C H The complex coupling equations are as follows:

[0076]

[0077] In the formula, ΔU L I represents the mutual inductance voltage phasor. CH U represents the phasor of the coupling capacitor branch current. Cp Y represents the equivalent node voltage phasor on the primary side. CS M represents the equivalent admittance of the secondary-side compensation capacitor branch. H Indicates mutual inductance to be identified, C HThis indicates that mutual compatibility needs to be identified.

[0078] Step 5: Based on the known parameters and complex equations obtained in Steps 2, 3, and 4, solve for the mutual inductance M. H With mutual compatibility C H To achieve parameter identification, the specific method is as follows:

[0079] The fundamental complex phasors U1, I1, and U extracted in step 3 are used to... Lp Substituting the intermediate expression constructed in step 4, we obtain U. Cp I CH and ΔU L Furthermore, by taking the real and imaginary parts of the complex coupling equation in step 4.5, a equation about the mutual inductance M is formed. H and mutual compatibility C H Solve the two sets of real number equations.

[0080] In this embodiment, the obtained M H The obtained C is 11.020µH. H It is 17.123 pF. (Reference) Figure 4 By comparing the simulated values ​​with the assumed theoretical values, it can be seen that the error value is small, which fully demonstrates that the method used in this invention is feasible and effective.

[0081] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for mutual inductance and mutual capacitance parameter identification of a hybrid coupled wireless power transfer system, characterized in that, The hybrid-coupled wireless power transfer system includes a DC power supply, a high-frequency inverter, a primary-side compensation network, a rectifier load module, and a sampling and calculation module; wherein, the hybrid coupling structure also includes the primary-side coil self-inductance L P Secondary coil self-inductance L S Magnetic coupling mutual inductance M H Mutual capacitance C with electric field coupling H The rectifier load module has a non-linear structure, including a rectifier bridge and a load resistor. The method includes the following steps: S1, at the system operating frequency f d Under fixed operating conditions, the sampling and calculation module collects the primary inverter output voltage u1(t), primary output current i1(t), and primary coil terminal voltage u1(t). Lp (t); S2. Select a steady-state integer period interval [t1, t2] from the acquired signal, and use the synchronous integration method to analyze u1(t), i1(t), and u... Lp (t) The fundamental frequency is extracted to obtain the operating frequency f. d The fundamental complex phasors U1, I1 and U are below Lp ; S3. Based on the circuit topology of the primary-side compensation network, considering the parasitic resistance R of the primary-side compensation capacitor. C1 R Cp and the parasitic resistance R of the primary coil p In the case of the fundamental complex vector obtained in step S2, the equivalent node voltage vector U on the primary side is constructed. Cp , Coupling capacitor branch current phasor I CH and mutual inductance voltage phasor ΔU L ; S4, Establish a system containing unknown mutual inductance M H Mutual compatibility with the unknown C H The complex coupling equations are obtained by separating the real and imaginary parts of the complex coupling equations to form a system of equations, and solving them yields the mutual inductance M. H With mutual compatibility C H The value.

2. The mutual inductance and mutual capacitance parameter identification method of a hybrid coupled wireless power transfer system according to claim 1, wherein, The step S2, which involves using the synchronous integration method to extract the fundamental frequency of the signal, specifically includes: Within the steady-state integer period interval [t1, t2], the time-domain signal x(t) to be extracted is compared with the fundamental reference complex exponential signal. By multiplying and integrating, the fundamental complex phasor of the signal at the operating frequency is obtained. Its expression is: In the formula, This refers to the system's operating angular frequency; The time length of the steady-state integer periodic interval [t1, t2] satisfy T d The system's operating cycle is N, where N is a positive integer.

3. The method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system according to claim 2, characterized in that, The positive integer N in step S2 is ≥5; preferably, N consecutive complete cycles from the end of the data collection are selected for integration, where N ≥ 10.

4. The method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system according to claim 1, characterized in that, The step S3 once side equivalent node voltage phasor U Cp , coupling capacitance branch current phasor I CH , mutual inductance voltage phasor ΔU L respectively satisfy: In the formula, U1 represents the fundamental complex phasor of the primary-side inverter output voltage, I1 represents the fundamental complex phasor of the primary-side output current, and U Lp C represents the fundamental complex phasor of the primary winding terminal voltage. t1 Indicates the primary-side compensation capacitor; C p This indicates the primary side compensation capacitor.

5. The method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system according to claim 1, characterized in that, The step S4 mentioned includes the unknown mutual inductance M H Mutual compatibility with the unknown C H The complex coupling equations satisfy: Take the real and imaginary parts of the complex coupling equation to form two real equations, and solve for the mutual inductance M. H With mutual compatibility C H .

6. A method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system according to any one of claims 1 to 5, characterized in that, Before the fundamental frequency extraction in step S2, a preprocessing step is also included: processing the voltage u1(t), current i1(t), and voltage u in the steady-state region. Lp (t) The signal is processed to remove the DC component, eliminating the DC bias caused by the switching action of the high-frequency inverter and the nonlinearity of the rectifier load; after obtaining the fundamental complex phasor, the parameter identification calculation of subsequent steps S3 to S4 is performed using the fundamental equivalent model.

7. The method for identifying mutual inductance and mutual capacitance parameters in a hybrid coupled wireless power transmission system according to claim 1, characterized in that, The high-frequency inverter has a nonlinear structure and uses a single-phase full-bridge inverter circuit. Its output voltage is a square wave with a fixed duty cycle, and its fundamental effective value satisfies the following: In the formula, This represents the fundamental RMS value of the output voltage of the high-frequency inverter. This is the output DC voltage value of the DC power supply.

8. A hybrid coupled wireless power transfer system, characterized in that, The method includes an execution module for identifying mutual inductance and mutual capacitance parameters as described in any one of claims 1 to 7, wherein the execution module is configured to perform steps S1 to S4 to achieve online parameter identification.

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