A parameter identification method for electric vehicle wireless charging system

Abstract

The present invention discloses a parameter identification method for an electric vehicle wireless charging system, which is applied to an electric vehicle wireless charging system using an SS compensation structure and includes the following steps: (1) reading the nominal values ​​of relevant parameters from the internal storage of a controller; (2) a sensor collecting data such as voltage, current, and operating frequency in real time according to a set sampling period; (3) calculating the corresponding parameters based on the normalized spectrum characteristic formula of the electric vehicle wireless charging system with the SS compensation structure; (4) determining whether parameter deviations such as inductance / capacitance, load, and frequency are taken into account; if not, identifying the coupling coefficient, calculating the mutual inductance value, and judging whether the parameters are within the allowable range; (5) if considered, first estimating the coupling coefficient, and equating the capacitance deviation to the self-inductance deviation, and then identifying all parameters. The present invention can realize rapid parameter identification of an electric vehicle wireless charging system based on the measurement of current, voltage, and operating frequency.

Description

Technical Field

[0001] The present invention relates to the field of wireless charging of electric vehicles, and in particular to a method for identifying parameters of a wireless charging system of an electric vehicle. Background Art

[0002] In the 21st century, the prospects for practical application of electric vehicles are becoming increasingly clear, and wireless charging technology for automotive batteries has become a hot topic of research. Efficiency is crucial to the charging process, and for wireless charging of electric vehicles, the coupling strength between the receiving and transmitting coils significantly impacts the system's transmission efficiency and power. During the actual charging process, misalignment between the receiving and transmitting coils, as well as slight variations in inductance, capacitance, or other parameters, inevitably affect the coupling coefficient, which in turn impacts the system's transmission efficiency and power. Therefore, identifying the coupling coefficient between the receiving and transmitting coils in an electric vehicle wireless charging system is essential.

[0003] Current methods for identifying parameters of electric vehicle wireless charging systems have problems such as complex algorithms and inaccurate identification. The solution process requires a large amount of computation, which increases the difficulty and complexity of implementation and increases system costs. In addition, there are limitations on the types of identification parameters, which greatly reduces the accuracy and reliability of identification. It does not take into account the possible load and position changes that may occur during the wireless charging process of electric vehicles, resulting in charging efficiency not reaching the maximum. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention proposes a parameter identification method for an electric vehicle wireless charging system. The method aims to rapidly identify the parameters of an SS-compensated electric vehicle wireless charging system based on the measurements of current, voltage, and operating frequency. This method improves the accuracy and reliability of the parameter identification results, simplifies the computer parameter identification process, and reduces system complexity, thereby ensuring the operating efficiency of the electric vehicle wireless charging system.

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

[0006] The present invention provides a parameter identification method for an electric vehicle wireless charging system, wherein the electric vehicle wireless charging system adopts an SS compensation structure. The parameter identification method is performed according to the following steps:

[0007] Step 1: When the electric vehicle wireless charging system is started, the nominal values ​​of the system parameters are read from the memory of the internal controller of the wireless charging system, including: the nominal value of the self-inductance of the transmitting end coil L P0 , the nominal value of the transmitter series compensation capacitor C P0 , nominal value of the receiving coil self-inductance L S0 , the nominal value of the receiving end compensation capacitor C S0 ;

[0008] Step 2: The electric vehicle wireless charging system receives a control command from a host computer, including: identifying a parameter type command PIT;

[0009] Step 3: Set the current number of cycles in the current wireless charging to i;

[0010] The electric vehicle wireless charging system obtains the sensor signal of the vehicle in the i-th cycle in real time, including: the output voltage value of the i-th cycle The input voltage value of the i-th cycle The output current value of the i-th cycle

[0011] Step 4: The controller calculates the parameters of the current wireless charging, including: coil self-inductance ratio λ L , transmitter resonant frequency f P , the ratio of the resonant frequency between the receiving end and the transmitting end λ f , normalized frequency f n ;

[0012] The controller calculates the average input voltage of the i-th cycle under the current wireless charging The average output voltage of the i-th cycle The average output current of the i-th cycle The equivalent load resistance of the i-th cycle The equivalent load factor of the i-th cycle The normalized frequency of the i-th cycle The coil self-inductance ratio of the i-th cycle The equivalent load factor of the i-th cycle

[0013] Step 5: The controller commands PIT to identify the corresponding parameters according to the identification parameter type:

[0014] Step 5.1: If the identification parameter type command PIT is 0, it means that the host computer has given an instruction to identify only the coupling coefficient and mutual inductance value, and execute steps 5.2 to 5.4;

[0015] If the identification parameter type command PIT is 1, it means that the host computer has given an instruction to identify all parameters and jumps to steps 5.5 to 5.11;

[0016] Step 5.2: Utilize the voltage gain of the electric vehicle wireless charging system Identify the exact coupling coefficient With accurate mutual inductance value

[0017] Step 5.3: Utilizing the Current-Voltage Gain of the Electric Vehicle Wireless Charging System For the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction to obtain the corrected precise coupling coefficient of the i-th cycle and calibrate the precise mutual inductance value

[0018] Step 5.4: Calculate the mutual inductance error of the i-th cycle

[0019] If e M (i) <Δ, it means that the mutual inductance value M of the i-th cycle is obtained (i) The final identification result is

[0020] If e M (i) >Δ, then it represents the mutual inductance value M of the i-th cycle (i) If there is an error, assign i+1 to i and return to step 5.2.1 to execute sequentially; Δ represents the mutual inductance error threshold;

[0021] Step 5.5: Calculate the transmitter self-inductance L of the i-th cycle using formula (11): P (i) Deviation rate The receiving end self-inductance L of the i-th cycle S (i) Deviation rate The transmitter compensation capacitor C of the i-th cycle P (i) Deviation rate The receiving end compensation capacitor C of the i-th cycle S (i) Deviation rate

[0022]

[0023] In formula (11), ΔL P (i) The self-inductance L of the transmitting coil in the i-th cycle is represented by P (i) and the nominal value of the transmitting coil self-inductance L P0 The difference, ΔL S (i) The self-inductance L of the receiving coil in the i-th cycle is represented by S (i) and the nominal value of the receiving coil self-inductance L S0 The difference, ΔC P (i) represents the transmitter compensation capacitance C of the i-th cycleP (i) The nominal value of the compensation capacitor in series with the transmitter is C P0 The difference, ΔC S (i) represents the receiving end compensation capacitor C of the i-th cycle S (i) and the nominal value of the receiving end compensation capacitor C S0 The difference between

[0024] Step 5.6: Use formula (12) to set the transmitter compensation capacitor C of the i-th cycle to P (i) Deviation rate The receiving end compensation capacitor C of the i-th cycle S (i) Deviation rate Equivalent to the self-inductance L of the transmitting coil in the i-th cycle P (i) Deviation rate The receiving coil self-inductance L of the i-th cycle S (i) Deviation rate

[0025]

[0026] Step 5.7: Identify the exact coupling coefficient of the i-th cycle according to the process of steps 5.2 and 5.3. The exact mutual inductance value of the i-th cycle And the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction;

[0027] Step 5.8: Use the voltage gain G of the ith cycle of the electric vehicle wireless charging system V (i) Identify all parameters using the correction relationship with the system parameters:

[0028] Let the parameter deviation rate of the i-th cycle be δ (i) , and δ (i) Contains δ k (i) , δ P (i) , δ S (i) , use formula (13) to construct the voltage gain G of the i-th cycle V (i) Deviation rate δ from the included parameter (i) The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is:

[0029]

[0030] In formula (13), δ k (i) is the deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, δ P (i) is the deviation rate of the self-inductance of the transmitting coil in the i-th cycle, δ S (i) is the deviation rate of the receiving coil self-inductance in the i-th cycle; g (i) (δ k (i) , δ P (i) , δ S (i) ) is the system parameter deviation function of the voltage gain of the i-th cycle; g (i) (0, 0, 0) represents g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0, the function value, Indicates g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0 for δ k (i) The partial derivative of Indicates g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0 for δP (i) The partial derivative of Indicates g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0 for δ S (i) The partial derivative of

[0031] The parameter deviation rate δ of the i-th cycle is determined using formula (14): (i) :

[0032]

[0033] In formula (14), J (i) The function g representing the i-th cycle (i) (δ k (i) , δ P (i) , δ S (i) )’s Jacobian matrix, r (i) is the residual vector of the i-th cycle, and contains the function g of the i-th cycle (i) (δ k (i) , δ P (i) , δ S (i) ) all residuals;

[0034] Step 5.9: Use formula (15) to construct the current-voltage gain of the i-th cycle Deviation rate δ from the included parameter (i) The relationship between the system parameters of the i-th cycle is:

[0035]

[0036] In formula (15), g'(δ k (i) , δ P (i) , δ S (i) ) is the system parameter deviation function of the current-voltage gain of the i-th cycle;

[0037] Use formula (16) to determine the correction parameter deviation rate δ' of the i-th cycle (i) :

[0038]

[0039] In formula (16), J' (i) The function g'(δ k (i) , δ P (i) , δ S (i) )’s Jacobian matrix, r’ (i) is the residual vector of the i-th cycle, and contains the function g'(δ k (i) , δ P (i) , δ S (i) ) all residuals;

[0040] Step 5.10: Calculate the parameter deviation of the i-th cycle

[0041] If e δ (i) <Δ', it means that the parameter deviation rate δ of the i-th cycle is obtained (i) The final identification result is

[0042] If e δ (i) >Δ', then it represents the parameter deviation rate δ of the i-th cycle (i) If there is an error, assign i+1 to i and return to step 5.5 to execute sequentially; Δ' represents the parameter deviation threshold;

[0043] Step 5.11: Calculate the identification values ​​of all parameters in the i-th cycle:

[0044] According to equations (17) to (19), the corrected precise coupling coefficient of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is obtained: Equivalent self-inductance of the transmitting coil in the i-th cycle Equivalent self-inductance of the receiving coil in the i-th cycle The self-inductance ratio of the receiving end to the transmitting end in the i-th cycle Normalized operating frequency of the i-th cycle Equivalent load factor of the i-th cycle and the corrected precise mutual inductance of the i-th cycle

[0045]

[0046]

[0047]

[0048] In formula (17), is the exact deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, is the precise deviation rate of the self-inductance of the transmitting coil in the i-th cycle, is the precise deviation rate of the receiving coil self-inductance in the i-th cycle;

[0049] The normalized input impedance Z of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is calculated by formula (20): n (i) :

[0050]

[0051] The input impedance Z of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is identified by formula (21): n (i) |:

[0052]

[0053] The input impedance angle of the i-th cycle is identified by formula (22):

[0054]

[0055] The corrected coupling coefficient of the i-th cycle is Calibrate accurate mutual inductance Equivalent self-inductance of the transmitting coil Equivalent self-inductance of the receiving coil Ratio of self-inductance between the receiving end and the transmitting end Normalized operating frequency Equivalent load factor Input impedance |Z n (i) | and input impedance angle As the identification result of the i-th cycle of the electric vehicle wireless charging system under the current wireless charging.

[0056] The parameter identification method of the electric vehicle wireless charging system according to the present invention is also characterized in that step 5.2 includes:

[0057] Step 5.2.1, let f n = 1, the estimated coupling coefficient of the i-th cycle is obtained using formula (1)

[0058]

[0059] In formula (1), L P Indicates the self-inductance of the transmitting coil;

[0060] Step 5.2.2: Use formula (2) to construct the voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is:

[0061]

[0062] In formula (2), the voltage gain Represents the output voltage value of the i-th cycle The input voltage value of the i-th cycle The ratio of express The coefficient of , and obtained by formula (3), express The coefficient of , and obtained by formula (4), express The coefficient of is obtained by formula (5);

[0063]

[0064]

[0065]

[0066] Step 5.2.3: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Fitting is performed to obtain the coupling coefficient deviation Δk of the i-th cycle (i) ;

[0067] Step 5.2.4: Use formula (6) to get the estimated coupling coefficient The precise identification result of the i-th cycle is the precise coupling coefficient

[0068]

[0069] Step 5.2.5: Obtain the exact mutual inductance value of the i-th cycle according to formula (7):

[0070]

[0071] In formula (7), L S Indicates the self-inductance of the receiving coil.

[0072] The step 5.3 includes:

[0073] Step 5.3.1: Use equation (8) to construct the current-voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is:

[0074]

[0075] In formula (8), the current-voltage gain Represents the output current value of the i-th cycle The input voltage value of the i-th cycle The ratio of

[0076] Step 5.3.2: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Perform fitting to obtain the correction coupling coefficient deviation Δk' of the i-th cycle (i) ;

[0077] Step 5.3.3: Use formula (9) to obtain the estimated coupling coefficient of the i-th cycle The corrected precise identification result, that is, the corrected precise coupling coefficient

[0078]

[0079] Step 5.3.4: Obtain the corrected precise mutual inductance value of the i-th cycle according to formula (10):

[0080]

[0081] An electronic device of the present invention includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the parameter identification method, and the processor is configured to execute the program stored in the memory.

[0082] The present invention provides a computer-readable storage medium, wherein a computer program is stored on the computer-readable storage medium, and the computer program executes the steps of the parameter identification method when the computer program is executed by a processor.

[0083] Compared with the existing technology, the beneficial effects of the present invention are embodied in:

[0084] 1. The present invention controls the sampling period command, sampling number command, parameter identification period command, and identification parameter type command through the host computer, and can change the sampling period and sampling number under different identification states or external environments. Compared with the traditional SS electric vehicle wireless charging system, the present invention realizes adjustable sampling period, and can adjust the initial identification data according to changes in working conditions, thereby making the identification results more accurate.

[0085] 2. In the present invention, voltage gain is used to accurately identify relevant system parameters, and then current-voltage gain is used to diagnose and correct the identification results. Compared with the traditional SS electric vehicle wireless charging system, the present invention improves the accuracy and reliability of parameter identification results.

[0086] 3. The identification process of the present invention utilizes a minimalist optimization method for calculation, transforming the nonlinear parameter identification problem into a linear parameter identification problem in a complex identification process, thus simplifying the solution process. Compared to traditional SS electric vehicle wireless charging systems, the present invention reduces the complexity of the computer system, ultimately enabling rapid and accurate identification of parameters such as the coupling coefficient between the receiving and transmitting coils of the electric vehicle wireless charging system, as well as load, equivalent deviation of the transmitting coil self-inductance, equivalent deviation of the receiving coil self-inductance, operating frequency, and input impedance angle. This enables safer, faster, more effective, and more targeted parameter identification, thereby improving the operating efficiency of the electric vehicle wireless charging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0087] Figure 1 Schematic diagram of the overall process of the electric vehicle wireless charging system parameter identification method of the present invention;

[0088] Figure 2 It is a schematic diagram of the early data collection and preparation process of the present invention;

[0089] Figure 3 It is a flow chart of the parameter identification process of the present invention;

[0090] Figure 4 This is a circuit diagram of the SS compensation wireless charging system of the present invention;

[0091] Figure 5 FIG. 4 is a schematic diagram of the AC equivalent circuit of the SS compensated WCS of the present invention. DETAILED DESCRIPTION

[0092] In this embodiment, a parameter identification method for an electric vehicle wireless charging system is a method that comprehensively considers system characteristics, operating conditions, and controllability. The electric vehicle wireless charging system in this method adopts an electric vehicle wireless charging system with an SS compensation structure, such as Figure 4 As shown, the wireless charging system includes a power supply ( Figure 4 U in in), inverter, primary side S-type compensation network ( Figure 4 C in P ), transmitting coil, receiving coil, secondary side S-type compensation network ( Figure 4 C in S ), rectifier filter circuit, load, DC power supply U in It is input into the MC-WPT system, and then converted into high-frequency alternating current by the full-bridge inverter and input into the primary side S-type compensation network, so that the transmitting coil generates a high-frequency alternating magnetic field. The receiving coil is coupled to the high-frequency alternating current and input into the secondary side S-type compensation network. It is then converted back into DC power U through the rectifier and filter circuit. o , provided to electrical equipment. Figure 5 In, L P is the self-inductance of the transmitting coil, L S is the receiving coil self-inductance, C P is the primary side series compensation capacitor, C S is the secondary side series compensation capacitor, M is the mutual inductance of the transmitting coil and the receiving coil, Figure 5 This is a schematic diagram of the AC equivalent circuit of the SS compensation WCS of the present invention, as shown in Figure 1 As shown in Figure 2, the parameter identification method is carried out in the following steps:

[0093] Step 1: Read the nominal values ​​of system parameters and system default settings from the controller's internal storage:

[0094] When the electric vehicle wireless charging system is started, the nominal values ​​of the system parameters are read from the memory of the internal controller of the wireless charging system, including: the nominal value of the self-inductance of the transmitting end coil L P0 , the nominal value of the transmitter series compensation capacitor C P0 , nominal value of the receiving coil self-inductance L S0 , the nominal value of the receiving end compensation capacitor C S0 .

[0095] Step 2: Receive control commands from the host computer:

[0096] The electric vehicle wireless charging system receives relevant commands from the host computer, including: sampling period command T0, sampling number command N0, parameter identification period command T1 and identification parameter type command PIT.

[0097] Step 3: Sensor data collection:

[0098] The electric vehicle wireless charging system obtains the sensor signal of the vehicle in real time during any wireless charging, including: the input current value I in , the output current value I during any wireless charging out , the input voltage value V during any wireless charging in, the output voltage value V during any wireless charging out , the real-time operating frequency f during any wireless charging;

[0099] Set the current number of cycles in the current wireless charging to i;

[0100] The electric vehicle wireless charging system obtains the sensor signal of the vehicle in the i-th cycle in real time, including: the output voltage value of the i-th cycle Input voltage value of the i-th cycle Output current value of the i-th cycle

[0101] Step 4: Figure 2 As shown in the spectrum characteristic formula of the electric vehicle wireless charging system based on SS compensation, the controller uses the parameters and data obtained in steps 1, 2 and 3 to calculate the parameters of any wireless charging, including: average input voltage Average input current Average output voltage Average output current and average operating frequency Equivalent load resistance R eq,ac , coil self-inductance ratio λ L , compensation capacitance ratio λ C , transmitter resonant frequency f P , receiving end resonant frequency f S , the ratio of the resonant frequency between the receiving end and the transmitting end λ f , characteristic impedance Z0, normalized frequency f n , equivalent load factor R n ; The controller calculates the average input voltage of the i-th cycle The average output voltage of the i-th cycle The average output current of the i-th cycle Equivalent load resistance of the i-th cycle Equivalent load factor of the i-th cycle Normalized frequency of the i-th cycle The coil self-inductance ratio of the i-th cycle Equivalent load factor of the i-th cycle

[0102] Step 4.1: First, determine the sampling number N according to formula (1) through the sampling period command T0, sampling number command N0, and parameter identification period command T1 received by the host computer:

[0103]

[0104] Take N input voltage sample data, recorded as {V in_1 ,Vin_2 ,…,V in_k ,…,V in_N}, N input current sample data, recorded as {I in_1 ,I in_2 ,…,I in_k ,…,I in_N}, N output voltage sample data, recorded as {V out_1 ,V out_2 ,…,V out_k ,…,V out_N}, N output current sample data, recorded as {I out_1 ,I out_2 ,…,I out_k ,…,I out_N}, N working frequency sample data, recorded as {f1,f2,…,f k ,…,f N}; where V in_k Indicates the kth input voltage value among the N sample data taken, I in_k Indicates the kth input current value among the N sample data, V out_k Indicates the kth output voltage value among the N sample data taken, I out_k Indicates the kth output current value among the N sample data taken, k = 1, 2…, N;

[0105] Then calculate the average input voltage according to formula (2) to formula (6) based on N sample data Average input current Average output voltage Average output current and average operating frequency

[0106]

[0107]

[0108]

[0109]

[0110]

[0111] Then, the equivalent load resistance of the wireless charging system in the i-th cycle is calculated according to formula (7):

[0112]

[0113] Step 4.2: Calculate the coil self-inductance λ according to the parameters and data obtained in steps 1, 2, and 3 using equations (8) to (15). L , compensation capacitance ratio λ C , transmitter resonant frequency f P , receiving end resonant frequency f S , the ratio of the resonant frequency between the receiving end and the transmitting end λ f , characteristic impedance Z0, normalized frequency f n , equivalent load factor R n :

[0114] Coil self-inductance ratio λ L :

[0115]

[0116] Compensation capacitance ratio λ C :

[0117]

[0118] Transmitter resonant frequency f P :

[0119]

[0120] Resonant frequency f at the receiving end S :

[0121]

[0122] The ratio of the resonant frequency between the receiving end and the transmitting end is λ f :

[0123]

[0124] Characteristic impedance Z0:

[0125]

[0126] Normalized frequency f n :

[0127]

[0128] Equivalent load factor R n :

[0129]

[0130] Step 5: Figure 3 As shown, the controller commands PIT according to the identification parameter type to identify the corresponding parameters:

[0131] Step 5.1, determine the identification parameter type (identification parameter type is 0 and 1, the default value is 0):

[0132] If the electric vehicle wireless charging system meets the static charging conditions or the host computer issues an instruction to identify only the coupling coefficient and mutual inductance value, and the identification parameter type command PIT is 0, the deviation of the coil self-inductance, compensation capacitance and other parameters in the SS compensation wireless charging system will be ignored. Only the coupling coefficient k and mutual inductance M of the transmitting and receiving coils will be identified, and the process will jump to steps 5.2-5.4.

[0133] If the electric vehicle wireless charging system meets the dynamic charging conditions or the host computer gives the instruction to identify all parameters, the identification parameter type command PIT is 1, then it is necessary to comprehensively consider the deviation of parameters such as the SS compensation wireless charging system coil self-inductance and compensation capacitance, and identify the SS compensation wireless charging system coupling coefficient k, mutual inductance M, transmitter coil self-inductance L P , receiving coil self-inductance L S , operating frequency f n 、Load R n , input impedance Z n and input impedance angle If the parameters are the same, skip to step 5.5-step 5.11.

[0134] Step 5.2: When the identification parameter type instruction PIT is 0, use the voltage gain of the electric vehicle wireless charging system Identify the exact coupling coefficient With accurate mutual inductance value

[0135] Step 5.2.1, let f n = 1, and thus the estimated coupling coefficient of the i-th cycle is obtained using formula (16)

[0136]

[0137] Then, the precise identification of the coupling coefficient k is performed.

[0138] Step 5.2.2: Voltage gain of the ith cycle of the electric vehicle wireless charging system Calculate according to formula (17):

[0139]

[0140] Transform Equation (17) into Equation (18) to construct the voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is:

[0141]

[0142] remember

[0143] get:

[0144]

[0145] In formula (19), express The coefficient of express The coefficient of express The coefficient of .

[0146] Step 5.2.3: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Perform fitting to obtain the Jacobian matrix J of the i-th cycle (i) According to formula (20):

[0147]

[0148] Residual vector r (i) According to formula (21):

[0149]

[0150] The coupling coefficient deviation Δk of the i-th cycle is calculated according to formula (22): (i) :

[0151]

[0152] Step 5.2.4: The estimated coupling coefficient of the i-th cycle The coupling coefficient deviation Δk from the i-th cycle (i) Add together to get the estimated coupling coefficient The precise identification result of the i-th cycle is the precise coupling coefficient Calculated by formula (23):

[0153]

[0154] Step 5.2.5: Obtain the exact mutual inductance value of the i-th cycle according to formula (24):

[0155]

[0156] Step 5.3: Utilizing the Current-Voltage Gain of the Electric Vehicle Wireless Charging System For the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction:

[0157] Step 5.3.1. Current-voltage gain of the electric vehicle wireless charging system in the i-th cycle for:

[0158]

[0159] Transform Equation (25) into Equation (26) to construct the current-voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is:

[0160]

[0161] get:

[0162]

[0163] Step 5.3.2: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Perform fitting to obtain the Jacobian matrix J (i) According to formula (28):

[0164]

[0165] Residual vector r (i) According to formula (29):

[0166]

[0167] According to formula (30), the correction coupling coefficient deviation Δk' of the i-th cycle is obtained (i) :

[0168]

[0169] Step 5.3.3: Add the estimated coupling coefficient k0 to the corrected coupling coefficient deviation Δk', which is the estimated coupling coefficient for the i-th cycle. The corrected precise identification result, that is, the corrected precise coupling coefficient Calculated by formula (31):

[0170]

[0171] Step 5.3.4: Obtain the corrected mutual inductance value of the i-th cycle according to formula (32):

[0172]

[0173] Step 5.4: Calculate the mutual inductance error e of the i-th cycle M(i) :

[0174] Using the voltage gain G V and the current-voltage gain G CV The identified mutual inductance error is denoted as

[0175] If e M (i) <Δ, it means the mutual inductance value M of the i-th cycle is obtained (i) The final identification result is

[0176] If e M (i) >Δ, it means that the identification result of the i-th cycle is incorrect, and after assigning i+1 to i, return to step 5.2.1 and execute sequentially; Δ represents the mutual inductance error threshold;

[0177] If the multiple identification results are greater than Δ, an error will be reported and the identification program will exit.

[0178] Step 5.5: When the identification parameter type command PIT is 1, the transmitter compensation capacitance deviation C' of the i-th cycle is P (i) Equivalent to the self-inductance deviation L' of the transmitting coil in the i-th cycle P (i) , the compensation capacitance deviation C' of the receiving end of the i-th cycle S (i) Equivalent to the self-inductance deviation L' of the receiving coil in the i-th cycle S (i) , first estimate the coupling coefficient, then estimate all parameters:

[0179] The value of a component parameter in the compensation network of the electric vehicle wireless charging system changes. Calculate the input impedance Z of the i-th cycle. n (i) , the input impedance angle of the i-th cycle

[0180] The self-inductance L of the transmitting coil in the i-th cycle P (i) The parameter deviation is expressed as The transmitter compensation capacitor C of the i-th cycle P (i) The parameter deviation is expressed as The self-inductance L of the receiving coil in the i-th cycle S (i) The parameter deviation is expressed as The receiving end compensation capacitor C of the i-th cycle S (i) The parameter deviation is expressed as The input impedance Z of the i-th cycle is represented by the universal function Ψ n (i) , the input impedance angle of the i-th cycle The voltage gain G of the i-th cycle V (i)

[0181] , the current-voltage gain of the i-th cycle Correspondingly, the self-inductance deviation L' of the transmitting coil for the i-th cycle is P (i) , transmitter compensation capacitance deviation C' P (i) , receiving end coil self-inductance deviation L' S (i) , receiving end compensation capacitance deviation C' S (i) Calculate the input impedance Z of the i-th cycle according to equations (33) to (36): n (i) , input impedance angle Voltage gain G V (i) and the current-voltage gain

[0182]

[0183]

[0184]

[0185]

[0186] in, is the transmitter self-inductance L P (i) The deviation rate, The receiving end self-inductance L S (i) The deviation rate, Compensation capacitor C for the transmitter P (i) The deviation rate, Compensation capacitor C for the receiving end S (i) The deviation rate is calculated by formula (37):

[0187]

[0188] In formula (37), ΔL P (i) The self-inductance L of the transmitting coil in the i-th cycle P (i) and the nominal value of the transmitting coil self-inductance LP0 The difference, ΔL S (i) The self-inductance L of the receiving coil in the i-th cycle S (i) and the nominal value of the receiving coil self-inductance L S0 The difference, ΔC P (i) Indicates the transmitter compensation capacitance C of the i-th cycle P (i) The nominal value of the compensation capacitor in series with the transmitter is C P0 The difference, ΔC S (i) Represents the receiving end compensation capacitor C of the i-th cycle S (i) and the nominal value of the receiving end compensation capacitor C S0 difference.

[0189] Step 5.6: According to the conversion relationship of formula (38), the transmitter compensation capacitor C P Deviation rate Receiver compensation capacitor C S Deviation rate Equivalent to the self-inductance L of the transmitting coil P Deviation rate Receiver coil self-inductance L S Deviation rate

[0190]

[0191] Step 5.7: Identify the exact coupling coefficient of the i-th cycle according to the process of steps 5.2 and 5.3. The exact mutual inductance value of the i-th cycle And the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction.

[0192] Step 5.8: Using the voltage gain G of the electric vehicle wireless charging system V Identify all parameters using the correction relationship with the system parameters:

[0193] will contain δ k (i) , δ P (i) , δ S (i) The parameter deviation rate of the i-th cycle is recorded as δ (i) , use formula (39) to construct the voltage gain G of the i-th cycle V (i) Deviation rate δ from the included parameter (i)The relationship between the system parameters of the i-th cycle is:

[0194]

[0195] In formula (39), δ k (i) is the deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, δ P (i) is the deviation rate of the self-inductance of the transmitting coil in the i-th cycle, δ S (i) is the deviation rate of the receiving coil self-inductance in the i-th cycle. g (i) (δ k (i) , δ P (i) , δ S (i) ) is the voltage gain system parameter deviation function of the i-th cycle, which is the right side of the equation (12), g (i) (0, 0, 0) represents g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0, the function value, Indicates g (i) (δ k (i) , v P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0 for δ k (i) The partial derivative of Indicates g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δS (i) =0 for δ P (i) The partial derivative of Indicates g (i) (δ k (i) , δ P (i) , δ S (i) ) in δ k (i) =0,δ P (i) =0,δ S (i) =0 for δ S (i) The partial derivative of .

[0196] Get g (i) (δ k (i) , δ P (i) , δ S (i) )’s Jacobian matrix J (i) According to formula (40), it can be expressed as

[0197]

[0198] vector r containing all residuals (i) According to formula (41), it can be expressed as:

[0199]

[0200] Then, the parameter deviation rate δ of the i-th cycle is determined by equation (42): (i) :

[0201]

[0202] Step 5.9: Use equation (43) to construct the current-voltage gain of the i-th cycle Deviation rate δ from the included parameter (i) The relationship between the system parameters of the i-th cycle.

[0203] Rewrite equation (39) in step 5.8 as:

[0204]

[0205] In formula (43), g'(δ k (i) , δ P (i) , δ S (i)) is the current-voltage gain system parameter deviation function of the i-th cycle;

[0206] Use formula (44) to determine the correction parameter deviation rate δ' of the i-th cycle (i) :

[0207]

[0208] In formula (44), J' (i) The function g'(δ k (i) , δ P (i) , δ S (i) )’s Jacobian matrix, r’ (i) is the residual vector and contains the function g'(δ k (i) , δ P (i) , δ S (i) ) all residuals;

[0209] Step 5.10: Calculate the parameter deviation of the i-th cycle

[0210] If e δ (i) <Δ', it means that the parameter deviation rate δ of the i-th cycle is obtained (i) The final identification result is

[0211] If e δ (i) >Δ', it means that the identification result of the i-th cycle is incorrect. After assigning i+1 to i, return to step 5.5 and execute sequentially; Δ' represents the parameter deviation threshold;

[0212] If the multiple identification results are greater than Δ', an error will be reported and the identification program will exit.

[0213] Step 5.11: Calculate the identification values ​​of all parameters for the i-th cycle:

[0214] According to equations (45) to (47), the corrected precise coupling coefficient of the electric vehicle wireless charging system for the i-th cycle is obtained: Equivalent self-inductance of the transmitting coil in the i-th cycle Equivalent self-inductance of the receiving coil in the i-th cycle The self-inductance ratio of the receiving end to the transmitting end in the i-th cycle Normalized operating frequency of the i-th cycle Equivalent load factor of the i-th cycle and the corrected precise mutual inductance of the i-th cycle

[0215]

[0216]

[0217]

[0218] In formula (45), is the exact deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, is the exact deviation rate of the transmitter coil self-inductance in the i-th cycle, is the exact deviation rate of the receiving coil self-inductance in the i-th cycle.

[0219] According to formula (48), the normalized input impedance Z of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is calculated. n (i) :

[0220]

[0221] The input impedance Z of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is identified by formula (49): n (i) |:

[0222]

[0223] Calculate the input impedance angle of the i-th cycle according to formula (50):

[0224]

[0225] The corrected coupling coefficient of the i-th cycle is Calibrate accurate mutual inductance Equivalent self-inductance of the transmitting coil Equivalent self-inductance of the receiving coil Ratio of self-inductance between the receiving end and the transmitting end Normalized operating frequency Equivalent load factor Input impedance |Z n (i) | and input impedance angle As the identification result of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging.

[0226] In this embodiment, an electronic device includes a memory and a processor, wherein the memory is used to store a program that supports the processor to execute the above method, and the processor is configured to execute the program stored in the memory.

[0227] In this embodiment, a computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the steps of the above method are executed.

[0228] In this embodiment, the method is not limited to application in wireless charging systems for electric vehicles. After slight modifications based on specific usage conditions, it can be applied to various types of passenger cars, trolleybuses / trolleybuses, special vehicles, special vehicles, and other vehicles that require wireless charging, and has a wide range of applications.

[0229] In summary, the present invention comprehensively considers the inevitable effects of misalignment between the receiving coil and the transmitting coil and slight changes in the inductance and capacitance components or other parameters on the coupling coefficient during the actual charging process. The least squares method is used for calculation, and the nonlinear parameter identification problem is converted into a linear parameter identification problem in the complex identification process, which simplifies the solution process and reduces the system complexity. Ultimately, the coupling coefficient of the receiving coil and the transmitting coil of the electric vehicle wireless charging system, as well as parameters such as the load, the equivalent deviation of the transmitting coil self-inductance, the equivalent deviation of the receiving coil self-inductance, the operating frequency, and the input impedance angle can be quickly and accurately identified. Based on this, the transmission efficiency and transmission power of the electric vehicle wireless charging system can be effectively improved.

Claims

1. A parameter identification method for an electric vehicle wireless charging system, wherein the electric vehicle wireless charging system adopts an SS compensation structure, characterized in that: The parameter identification method is carried out in the following steps: Step 1: When the electric vehicle wireless charging system is started, the nominal values ​​of the system parameters are read from the memory of the internal controller of the wireless charging system, including: the nominal value of the self-inductance of the transmitting end coil; , Nominal value of transmitter series compensation capacitor , Nominal value of self-inductance of the receiving coil , nominal value of the compensation capacitor at the receiving end ; Step 2: The electric vehicle wireless charging system receives a control command from a host computer, including: identifying a parameter type command PIT; Step 3: Set the current number of cycles in the current wireless charging to i; The electric vehicle wireless charging system obtains the sensor signal of the vehicle in the i-th cycle in real time, including: the output voltage value of the i-th cycle The input voltage value of the i-th cycle , the output current value of the i-th cycle ; Step 4: The controller calculates the parameters of the current wireless charging, including: coil self-inductance ratio , transmitter resonant frequency , the resonant frequency ratio between the receiving end and the transmitting end , normalized frequency ; The controller calculates the average input voltage of the i-th cycle under the current wireless charging , the average output voltage of the i-th cycle , the average output current of the i-th cycle , the equivalent load resistance of the i-th cycle , the equivalent load factor of the i-th cycle , the normalized frequency of the i-th cycle , the coil self-inductance ratio of the i-th cycle , the equivalent load factor of the i-th cycle ; Step 5: The controller commands PIT to identify the corresponding parameters according to the identification parameter type: Step 5.1: If the identification parameter type command PIT is 0, it means that the host computer has given an instruction to identify only the coupling coefficient and mutual inductance value, and execute steps 5.2 to 5.4; If the identification parameter type command PIT is 1, it means that the host computer has given an instruction to identify all parameters and jumps to steps 5.5 to 5.11; Step 5.2: Utilize the voltage gain of the electric vehicle wireless charging system Identify the exact coupling coefficient With accurate mutual inductance value ; Step 5.3: Utilizing the Current-Voltage Gain of the Electric Vehicle Wireless Charging System For the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction to obtain the corrected precise coupling coefficient of the i-th cycle and calibrate the precise mutual inductance value ; Step 5.4: Calculate the mutual inductance error of the i-th cycle ; like , then the mutual inductance value of the i-th cycle is obtained The final identification result is ; like , then it represents the mutual inductance value of the i-th cycle If there is an error, assign i+1 to i and return to step 5.2.1 to execute sequentially; represents the mutual inductance error threshold; Step 5.5: Calculate the transmitter self-inductance of the i-th cycle using formula (11): Deviation rate , the receiving end self-inductance of the i-th cycle Deviation rate , the transmitter compensation capacitor of the i-th cycle Deviation rate , the receiving end compensation capacitor of the i-th cycle Deviation rate : (11) In formula (11), represents the self-inductance of the transmitting coil in the i-th cycle and the nominal value of the transmitting coil self-inductance The difference, represents the self-inductance of the receiving coil in the i-th cycle and the nominal value of the receiving coil self-inductance The difference, Represents the transmitter compensation capacitance of the i-th cycle Nominal value of compensation capacitor in series with the transmitter The difference, Represents the receiving end compensation capacitance of the i-th cycle and the nominal value of the compensation capacitor at the receiving end The difference between Step 5.6: Use formula (12) to set the transmitter compensation capacitor of the i-th cycle to Deviation rate , the receiving end compensation capacitor of the i-th cycle Deviation rate Equivalent to the self-inductance of the transmitting coil in the i-th cycle Deviation rate , the self-inductance of the receiving coil in the i-th cycle Deviation rate : (12) Step 5.7: Identify the exact coupling coefficient of the i-th cycle according to the process of steps 5.2 and 5.

3. The exact mutual inductance value of the i-th cycle , and the exact coupling coefficient With accurate mutual inductance value Perform diagnosis and correction; Step 5.8: Using the voltage gain of the ith cycle of the electric vehicle wireless charging system Identify all parameters using the correction relationship with the system parameters: Let the parameter deviation rate of the i-th cycle be ,and Include 、 、 , use formula (13) to construct the voltage gain of the i-th cycle Deviation rate from included parameters The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is: (13) In formula (13), is the deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, is the deviation rate of the self-inductance of the transmitting coil in the i-th cycle, is the deviation rate of the receiving end coil self-inductance in the i-th cycle; is the system parameter deviation function of the voltage gain of the i-th cycle; express exist The function value when express exist Time The partial derivative of express exist Time The partial derivative of express exist Time The partial derivative of is the estimated coupling coefficient of the i-th cycle; The parameter deviation rate of the i-th cycle is determined using formula (14): : (14) In formula (14), The function representing the i-th loop The Jacobian matrix of is the residual vector of the i-th cycle and contains the function of the i-th cycle All residuals of ; Step 5.9: Use formula (15) to construct the current-voltage gain of the i-th cycle Deviation rate from included parameters The relationship between the system parameters of the i-th cycle is: (15) In formula (15), is the system parameter deviation function of the current-voltage gain of the i-th cycle; Use formula (16) to determine the correction parameter deviation rate of the i-th cycle : (16) In formula (16), Function representing the i-th loop The Jacobian matrix of is the correction residual vector of the i-th cycle and contains the function of the i-th cycle All residuals of ; Step 5.10: Calculate the parameter deviation of the i-th cycle ; like , then it means that the parameter deviation rate of the i-th cycle is obtained The final identification result is ; like , then it represents the parameter deviation rate of the i-th cycle If there is an error, assign i+1 to i and return to step 5.5 to execute sequentially; represents the parameter deviation threshold; Step 5.11: Calculate the identification values ​​of all parameters in the i-th cycle: According to equations (17) to (19), the recalibrated precise coupling coefficient of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is obtained: , the equivalent self-inductance of the transmitting coil in the i-th cycle , the equivalent self-inductance of the receiving coil in the i-th cycle , the self-inductance ratio of the receiving end to the transmitting end in the i-th cycle , the normalized operating frequency of the i-th cycle , the equivalent load factor of the i-th cycle And the recalibration of the precise mutual inductance value in the i-th cycle : (17) (18) (19) In formula (17), is the exact deviation rate between the estimated value and the exact value of the coupling coefficient of the i-th cycle, is the precise deviation rate of the self-inductance of the transmitting coil in the i-th cycle, is the precise deviation rate of the receiving coil self-inductance in the i-th cycle; The normalized input impedance of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is calculated by formula (20): : (20) The input impedance of the electric vehicle wireless charging system in the i-th cycle under the current wireless charging is identified by formula (21): : (21) The input impedance angle of the i-th cycle is identified by formula (22): : (22) The accurate coupling coefficient is recalibrated with the i-th cycle , calibrate the precise mutual inductance value again , Equivalent self-inductance of the transmitting coil , Equivalent self-inductance of the receiving coil , the self-inductance ratio between the receiving end and the transmitting end , normalized operating frequency , equivalent load factor , input impedance and input impedance angle As the identification result of the i-th cycle of the electric vehicle wireless charging system under the current wireless charging.

2. The parameter identification method of the electric vehicle wireless charging system according to claim 1, characterized in that: The step 5.2 includes: Step 5.2.1, let When , the estimated coupling coefficient of the i-th cycle is obtained using formula (1) : (1) In formula (1), Indicates the self-inductance of the transmitting coil; Step 5.2.2: Use formula (2) to construct the voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is: (2) In formula (2), the voltage gain Represents the output voltage value of the i-th cycle The input voltage value of the i-th cycle The ratio of express The coefficient of , and obtained by formula (3), express The coefficient of , and obtained by formula (4), express The coefficient of is obtained by formula (5); (3) (4) (5) Step 5.2.3: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Fitting is performed to obtain the coupling coefficient deviation of the i-th cycle ; Step 5.2.4: Use formula (6) to get the estimated coupling coefficient The precise identification result of the i-th cycle is the precise coupling coefficient : (6) Step 5.2.5: Obtain the exact mutual inductance value of the i-th cycle according to formula (7): : (7) In formula (7), Indicates the self-inductance of the receiving coil.

3. The parameter identification method of the electric vehicle wireless charging system according to claim 2, characterized in that: The step 5.3 includes: Step 5.3.1: Use equation (8) to construct the current-voltage gain of the i-th cycle The relationship between the parameters of the i-th cycle in the electric vehicle wireless charging system is: (8) In formula (8), the current-voltage gain Represents the output current value of the i-th cycle The input voltage value of the i-th cycle The ratio of Step 5.3.2: Use the nonlinear least squares method to estimate the coupling coefficient of the i-th cycle Perform fitting to obtain the correction coupling coefficient deviation of the i-th cycle ; Step 5.3.3: Use formula (9) to obtain the estimated coupling coefficient of the i-th cycle The corrected precise identification result, that is, the corrected precise coupling coefficient : (9) Step 5.3.4: Obtain the corrected precise mutual inductance value of the i-th cycle according to formula (10): : (10)。 4. An electronic device comprising a memory and a processor, characterized in that: The memory is used to store a program that supports the processor to execute the parameter identification method according to any one of claims 1 to 3, and the processor is configured to execute the program stored in the memory.

5. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the parameter identification method according to any one of claims 1 to 3 are executed.

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