Variable frequency control method for wireless power transmission system based on model-free adaptive control

Abstract

The application provides a wireless power transmission system frequency conversion control method based on model-free adaptive control, belongs to the wireless power transmission field, and is used for solving the technical problem that the system constant voltage output cannot be ensured when the coupling coefficient k changes due to the deviation of a multi-relay power supply system in the prior art. The specific steps are as follows: a system frequency conversion controller of the wireless charging system based on a tight format dynamic linearization model-free adaptive control is established, the input of the system frequency conversion controller is a system input frequency, and the output of the system frequency conversion controller is a system output voltage; the expected output voltage of the system is collected, the input frequency of the system is controlled through the system frequency conversion controller based on the tight format dynamic linearization model-free adaptive control, and the output voltage approaches the expected output voltage. The application uses the model-free adaptive control mode to perform constant voltage control on the energy channel output, and then realizes stable long-distance wireless power transmission.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission, and in particular to a frequency conversion control method for wireless power transmission systems based on model-free adaptive control. Background Technology

[0002] Wireless power transfer (WPT) technology utilizes magnetic fields, electric fields, lasers, or other media to achieve contactless power transfer, offering advantages such as flexibility, safety, and reliability. In particular, magnetically coupled wireless power transfer (MC-WPT) technology has become a research hotspot in recent years. Transmission distance has always been a key issue limiting wireless power transfer technology. Currently, methods to improve transmission distance mainly include increasing the operating frequency, adding repeater coils, and optimizing impedance.

[0003] In some studies, the compensation network is removed to allow the system to operate in a self-resonant state. In this case, the operating frequency of the system is increased, and the power loss of the compensation network is reduced, thereby improving the system's power transmission capability. In other studies, repeater coils are added to extend the transmission distance between the transmitter and receiver stages, typically used for wireless power supply in online monitoring equipment for high-voltage transmission lines. However, high-power transmission at high operating frequencies is limited, and repeater coils occupy effective power transmission space, limiting the improvement in transmission distance through impedance optimization. As the transmission distance increases, the coupling coefficient decreases, and the transmission power and efficiency of traditional two-coil MC-WPT systems decrease significantly. Summary of the Invention

[0004] The purpose of this invention is to provide a frequency conversion control method for wireless power transmission systems based on model-free adaptive control. This method addresses the technical problem in existing technologies where constant voltage output cannot be guaranteed when the coupling coefficient k changes due to offset in multi-relay power supply systems.

[0005] A frequency conversion control method for a wireless power transfer system based on model-free adaptive control is disclosed. The wireless charging system includes a transmitting coil, a receiving coil, a first relay coil coplanar with the transmitting coil, and a second relay coil coplanar with the receiving coil. The specific steps of the frequency conversion control method are as follows:

[0006] S1: Establish a system frequency converter for the wireless charging system based on compact-format dynamic linearized model-free adaptive control. The input of the system frequency converter is the system input frequency, and the output of the system frequency converter is the system output voltage.

[0007] S2: Acquire the desired output voltage of the system, and control the input frequency of the system through the system frequency converter based on tight-form dynamic linearized model-free adaptive control to make the output voltage approach the desired output voltage.

[0008] Preferably, the specific steps for establishing the system frequency converter controller of the wireless charging system based on compact-format dynamic linearized model-free adaptive control in step S1 are as follows:

[0009] S1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system, and construct the conditions that the discrete-time nonlinear system needs to satisfy;

[0010] S1.2: Construct a compact-format dynamic linearized data model based on the discrete-time nonlinear system of the wireless charging system and the conditions to be satisfied;

[0011] S1.3: Set the parameter estimation criterion function and the system input frequency control criterion function for the compact-format dynamic linearized data model respectively, and calculate the estimator parameters and input frequency parameters of the model-free adaptive control of the system through the functions.

[0012] Preferably, the specific steps in step S1.1 for constructing the discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system, and for constructing the conditions that the discrete-time nonlinear system needs to satisfy, are as follows:

[0013] S1.1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system:

[0014] (1)

[0015] In the formula, for The system's input frequency at time t. for The system's output voltage at that moment, and respectively as System inputs and outputs, They are two unknown integers; It is an unknown nonlinear function;

[0016] S1.1.2: Assume that the discrete-time nonlinear system satisfies:

[0017] Except for finite points in time, Regarding the first The partial derivatives of the variables are continuous, and except at finite time points, the discrete-time nonlinear system satisfies the generalized Lipschitz condition, that is, for any... , and have:

[0018] (2)

[0019] In the formula, i=1, 2, b>0 is a constant.

[0020] As a preferred embodiment, the specific method for constructing a compact-format dynamic linearized data model based on the discrete-time nonlinear system of the wireless charging system and the conditions to be satisfied in step S1.2 is as follows:

[0021] The discrete-time nonlinear system satisfies for all K. The compact-format dynamic linearized data model of the discrete-time nonlinear system is as follows:

[0022] (3)

[0023] In the formula, Let be the pseudo-block Jacobian matrix of the system. The estimator parameters are for model-free adaptive control, and It is bounded for any time k. for Output voltage at time and Output voltage at time The difference, for Input frequency at time and Input frequency at time The difference.

[0024] Preferably, the specific method for setting the parameter estimation criterion function of the compact-format dynamic linearized data model and calculating the estimator parameters of the model-free adaptive control of the system through the function in step S1.3 is as follows:

[0025] Based on the compact-format dynamic linearized data model, the parameter estimation criterion function is given as follows:

[0026] (4)

[0027] In the formula, μ>0 is the weighting factor. for The PPD estimate; the parameter estimation criterion function with respect to To find the extreme value, the PPD estimation algorithm is as follows:

[0028] (5)

[0029] In the formula, It is the added step size factor that estimates the PPD. As The output.

[0030] As a preferred option, the specific method for setting the system input frequency control criterion function and calculating the system input frequency parameters through the function is as follows:

[0031] Based on the compact-format dynamic linearized data model, the system input frequency control criterion function is given as follows:

[0032] (6)

[0033] Here, λ>0 is a weighting factor used to penalize excessively large changes in the control input. for The desired output voltage of the system at any given time, for Taking the derivative and setting it equal to zero, we get:

[0034] (7)

[0035] In the formula, the step size factor Step size factor The addition of this makes the control algorithm more general.

[0036] As a preferred embodiment, the specific steps for controlling the system's input frequency using a system frequency converter based on tight-form dynamic linearized model-free adaptive control are as follows:

[0037] S2.1: Current data collection of wireless power transmission system Output voltage at time and Output voltage at time and the current Input frequency of the time system and Input frequency of the time system ,as well as The expected output voltage of the system at any time ;

[0038] S2.2: Based on the system's compact-format dynamic linearization data model calculate The theoretical value of the system output voltage at any given time :

[0039] (8);

[0040] S2.3: Based on the PPD estimation algorithm... The pseudo-block Jacobian matrix of the system at time step Perform calculations and based on and The expected output voltage of the system at any time Theoretical value of voltage ,right The frequency of the system is calculated at any time, and the frequency of the inverter is controlled based on the calculation results.

[0041] Because of the adoption of the above technical solution, the present invention has the following advantages:

[0042] 1. This application addresses a nonlinear wireless power transmission system where the number of repeater coils increases with the transmission distance. When the system offset causes a change in the coupling coefficient k, the system frequency can be adjusted to maintain a constant voltage output.

[0043] 2. This application uses a model-free adaptive control method to perform constant voltage control of the energy channel output, thereby achieving stable medium- and long-distance wireless power transmission.

[0044] 3. The movement of the energy receiving coil within a certain range in this application will cause changes in mutual inductance and coupling coefficient, which will lead to fluctuations in charging power and a reduction in efficiency. The model-free adaptive control method can avoid complex model building. After establishing the control model of the system solely based on the system's I / O data, it can solve the multivariable control problem that traditional PID cannot solve, expand the energy transfer space range, improve the energy transfer flexibility, and achieve the goal of stable power output. The added relay coil can greatly expand the charging range and charging flexibility, and can meet the charging needs of medium and long distances.

[0045] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained from the following description and claims. Attached Figure Description

[0046] The accompanying drawings of this invention are described below.

[0047] Figure 1 This is a flowchart of the frequency conversion control method of the present invention.

[0048] Figure 2 This is a schematic diagram of the coupling mechanism of the wireless power transmission system of the present invention.

[0049] Figure 3 This is a simplified circuit diagram of the wireless power transmission system of the present invention.

[0050] Figure 4 This is a Bode diagram of the four-coil wireless power transmission system of the present invention.

[0051] Figure 5 This is a Simulink simulation diagram of the wireless power transmission system of the present invention.

[0052] Figure 6 This is a structural diagram of the model-free adaptive controller of the present invention.

[0053] Figure 7 This is a control voltage waveform diagram when the distance between the transmitting coil and the receiving coil of the present invention is 35cm.

[0054] Figure 8 This is a control voltage waveform diagram when the distance between the transmitting coil and the receiving coil of the present invention is 40cm.

[0055] Figure 9 This is a control voltage waveform diagram when the distance between the transmitting coil and the receiving coil of the present invention is 45cm.

[0056] Figure 10 This is a control voltage waveform diagram when the distance between the transmitting coil and the receiving coil of the present invention is 50cm.

[0057] Figure 11 This is a frequency diagram for each transmission distance Gv=1 in this invention.

[0058] Figure 12 This is a frequency diagram of the present invention at various distances Gv=1 under the condition of 40k harmonic tuning. Detailed Implementation

[0059] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0060] Example 1:

[0061] like Figure 2 and Figure 3 The wireless power transmission system shown includes a transmitting coil L1, a receiving coil L4, a first relay coil L2 coplanar with the transmitting coil, and a second relay coil L3 coplanar with the receiving coil. Both the first relay coil L2 and the second relay coil L3 are passive coils.

[0062] In this example, a passive coil is added to the coupling mechanism on the same plane on both the primary and secondary sides, which can improve the transmission distance of the wireless power transmission system. This coupling mechanism does not occupy power transmission space and achieves high power transmission in the operating frequency range of several hundred kilohertz. It has stronger coupling capability and lower coil self-induced voltage than the dual-coil coupling structure, and is suitable for long-distance wireless power transmission.

[0063] In this example, such as Figure 3As shown, coils L1, L2, L3, and L4 are all series-compensated. C1, C2, C3, and C4 are the compensation capacitors for each coil, respectively. r1, r2, r3, and r4 are the internal resistances of the coils, respectively. M12, M13, M14, M23, M24, and M34 are the mutual inductance values ​​between the coils. Vin is the DC input power supply. Req is the equivalent load. The parameters of this system must meet the following requirements:

[0064] (9)

[0065] According to Kirchhoff's voltage law Figure 2 and Figure 3 The system model of the MC-WPT system shown can be represented as:

[0066] (10)

[0067] in (i, j = 1, 2, 3, 4, i ≠ j) represents the coupling coefficient between coils Li and Lj.

[0068] Simulation analysis was performed on this coupling mechanism at different distances, and the parameters are shown in Table 1.

[0069] Table 1 System Parameters

[0070]

[0071] The capacitor parameters are tuned at 200kHz, with M13, M14, M23, and M24 varying with the transmission distance. M12 and M34 remain constant.

[0072] The system parameters at other distances are shown in Table 2.

[0073] Table 2 System parameters under varying distances

[0074]

[0075] The voltage gain of the system can be expressed as:

[0076] (11)

[0077] The model cannot be solved directly. The Bode plot method of transfer function will be used to analyze the characteristics of the system. Taking the Bode plot of the system with a 35cm diameter as an example.

[0078] Depend on Figure 4As shown in the Bode plot, the system exhibits three voltage gain maxima at 200kHz harmonic tuning. Therefore, the system has three different voltage gain maxima at three different frequencies. This demonstrates that the four-coil system, as a high-order wireless power transfer system, has different voltage gains at different frequencies.

[0079] Example 2:

[0080] like Figure 1 The frequency conversion control method for a wireless power transfer system based on model-free adaptive control is shown below, with the following specific steps:

[0081] S1: Establish a system frequency converter for the wireless charging system based on compact-format dynamic linearized model-free adaptive control. The input of the system frequency converter is the system input frequency, and the output of the system frequency converter is the system output voltage. Specific steps are as follows:

[0082] S1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system, and construct the conditions that the discrete-time nonlinear system needs to satisfy; the specific steps are as follows:

[0083] S1.1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system:

[0084] (12)

[0085] In the formula, for The system's input frequency at time t. for The system's output voltage at that moment, and respectively as System inputs and outputs, They are two unknown integers; It is an unknown nonlinear function;

[0086] S1.1.2: Assume that the discrete-time nonlinear system satisfies:

[0087] Except for finite points in time, Regarding the first The partial derivatives of the variables are continuous, and except at finite time points, the discrete-time nonlinear system satisfies the generalized Lipschitz condition, that is, for any... , and have:

[0088] (13)

[0089] In the formula, i=1, 2, b>0 is a constant.

[0090] S1.2: Construct a compact-form dynamic linearized data model based on the discrete-time nonlinear system of the wireless charging system and the conditions to be satisfied; the specific method is as follows:

[0091] The discrete-time nonlinear system satisfies for all K. The compact-format dynamic linearized data model of the discrete-time nonlinear system is as follows:

[0092] (14)

[0093] In the formula, Let be the pseudo-block Jacobian matrix of the system. The estimator parameters are for model-free adaptive control, and It is bounded for any time k. for Output voltage at time and Output voltage at time The difference, for Input frequency at time and Input frequency at time The difference.

[0094] S1.3: Set the parameter estimation criterion function and the system input frequency control criterion function for the compact-format dynamic linearized data model respectively. Calculate the estimator parameters and input frequency parameters of the system's model-free adaptive control through these functions. The specific steps are as follows:

[0095] S1.3.1: Based on the compact-format dynamic linearized data model, the parameter estimation criterion function is given as follows:

[0096] (15)

[0097] In the formula, μ>0 is the weighting factor. for The estimated PPD value;

[0098] The parameter estimation criterion function with respect to To find the extreme value, the PPD estimation algorithm is as follows:

[0099] (16)

[0100] In the formula, It is the added step size factor that estimates the PPD. As The output;

[0101] S1.3.2: Based on the compact-format dynamic linearized data model, the system input frequency control criterion function is given as follows:

[0102] (17)

[0103] Here, λ>0 is a weighting factor used to penalize excessively large changes in the control input. for The desired output voltage of the system at any given time, for Taking the derivative and setting it equal to zero, we get:

[0104] (18)

[0105] In the formula, the step size factor Step size factor The addition of this makes the control algorithm more general.

[0106] S2: Acquire the desired output voltage of the system, and control the system's input frequency using a system frequency converter based on tight-form dynamic linearized model-free adaptive control to make the output voltage approach the desired output voltage. The specific steps are as follows:

[0107] S2.1: Current data collection of wireless power transmission system Output voltage at time and Output voltage at time and the current Input frequency of the time system and Input frequency of the time system ,as well as The expected output voltage of the system at any time ;

[0108] S2.2: Based on the system's compact-format dynamic linearization data model calculate The theoretical value of the system output voltage at any given time :

[0109] (19);

[0110] S2.3: Based on the PPD estimation algorithm... The pseudo-block Jacobian matrix of the system at time step Perform calculations and based on and The expected output voltage of the system at any time Theoretical value of voltage ,right The frequency of the system is calculated at any time, and the frequency of the inverter is controlled based on the calculation results.

[0111] In this embodiment, , and These represent the number of transmitting coils and receiving coils, respectively.

[0112] S2.4: Collect the system output voltage after frequency adjustment of the inverter, recalculate the estimator parameters and frequency until the system output voltage approaches or equals the desired output voltage.

[0113] In this embodiment, yes initial value, , .

[0114] In this embodiment, voltage sampling is performed at the load end, and the sampled voltage is sent back as follows: Figure 6 In the model-free adaptive controller shown, the latest frequency is calculated and sent back to the inverter for frequency conversion operation, ultimately achieving closed-loop control of a wide range of constant voltage output across the DC load under varying coupling coefficients.

[0115] S3: System Simulation:

[0116] The Simulink simulation diagram of the four-coil system is shown below. Figure 4 As shown, under 200kHz harmonic conditions, a 1:1 voltage gain is used to control the output voltage using a model-free adaptive control algorithm, with an input voltage of 387V.

[0117] according to Figure 6 , Figure 7 , Figure 8 , Figure 9 , Figure 10 and Figure 11 It can be seen that, under 200kHz harmonic tuning, model-free adaptive control can maintain the output voltage at approximately 387V at each distance. Furthermore, the frequency corresponding to voltage gain Gv=1 is not the same at different transmission distances; the frequencies are similar at 40cm and 45cm, but differ significantly at other distances. Under 40kHz harmonic tuning, while the frequencies corresponding to different distances are relatively close, they are not entirely identical. This indicates that the system frequency has a crucial impact on the system characteristics. This variation is not regular, and the model-free adaptive control method can adjust the frequency to control voltage gain Gv=1 for different transmission distances and varying coupling coefficient k.

[0118] Those skilled in the art will understand that embodiments of this application can be provided as methods, systems, or computer program products. Therefore, this application can take the form of a completely hardware embodiment, a completely software embodiment, or an embodiment combining software and hardware aspects. Furthermore, this application can take the form of a computer program product embodied on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0119] This application is described with reference to flowchart illustrations and / or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of this application. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing apparatus to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing apparatus, generate instructions for implementing the flowchart... Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0120] These computer program instructions may also be stored in a computer-readable storage medium that can direct a computer or other programmable data processing device to function in a particular manner, such that the instructions stored in the computer-readable storage medium produce an article of manufacture including instruction means, which are implemented in a process Figure 1 One or more processes and / or boxes Figure 1 The function specified in one or more boxes.

[0121] These computer program instructions may also be loaded onto a computer or other programmable data processing equipment to cause a series of operational steps to be performed on the computer or other programmable equipment to produce a computer-implemented process, thereby providing instructions that execute on the computer or other programmable equipment for implementing the process. Figure 1 One or more processes and / or boxes Figure 1 The steps of the function specified in one or more boxes.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A frequency conversion control method for a wireless power transfer system based on model-free adaptive control, the wireless charging system comprising a transmitting coil, a receiving coil, a first relay coil coplanar with the transmitting coil, and a second relay coil coplanar with the receiving coil, characterized in that, The specific steps of the frequency converter control method are as follows: S1: Establish a system frequency converter for the wireless charging system based on compact-format dynamic linearized model-free adaptive control. The input of the system frequency converter is the system input frequency, and the output of the system frequency converter is the system output voltage. S2: Acquire the desired output voltage of the system, and control the input frequency of the system through the system frequency converter based on tight-form dynamic linearized model-free adaptive control to make the output voltage approach the desired output voltage.

2. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 1, characterized in that, The specific steps for establishing the system frequency converter controller of the wireless charging system based on compact-format dynamic linearized model-free adaptive control in step S1 are as follows: S1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system, and construct the conditions that the discrete-time nonlinear system needs to satisfy; S1.2: Construct a compact-format dynamic linearized data model based on the discrete-time nonlinear system of the wireless charging system and the conditions to be satisfied; S1.3: Set the parameter estimation criterion function and the system input frequency control criterion function for the compact-format dynamic linearized data model respectively, and calculate the estimator parameters and input frequency parameters of the model-free adaptive control of the system through the functions.

3. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 2, characterized in that, The specific steps in step S1.1 for constructing the discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system, and for constructing the conditions that the discrete-time nonlinear system needs to satisfy, are as follows: S1.1.1: Construct a discrete-time nonlinear system of the input frequency and output voltage of the wireless charging system: （1） In the formula, for The system's input frequency at time t. for The system's output voltage at that moment, and respectively as System inputs and outputs, They are two unknown integers; It is an unknown nonlinear function; S1.1.2: Assume that the discrete-time nonlinear system satisfies: Except for finite points in time, Regarding the first The partial derivatives of the variables are continuous, and except at finite time points, the discrete-time nonlinear system satisfies the generalized Lipschitz condition, that is, for any... , and have: （2） In the formula, i=1, 2, b>0 is a constant.

4. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 3, characterized in that, The specific method for constructing a compact-format dynamic linearized data model based on the discrete-time nonlinear system of the wireless charging system and the conditions to be satisfied in step S1.2 is as follows: The discrete-time nonlinear system satisfies for all K. The compact-format dynamic linearized data model of the discrete-time nonlinear system is as follows: （3） In the formula, Let be the pseudo-block Jacobian matrix of the system. The estimator parameters are for model-free adaptive control, and It is bounded for any time k. for Output voltage at time and Output voltage at time The difference, for Input frequency at time and Input frequency at time The difference.

5. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 4, characterized in that, The specific method for setting the parameter estimation criterion function of the compact-format dynamic linearized data model in step S1.3 and calculating the estimator parameters of the model-free adaptive control of the system through the function is as follows: Based on the compact-format dynamic linearized data model, the parameter estimation criterion function is given as follows: （4） In the formula, μ>0 is the weighting factor. for The PPD estimate; the parameter estimation criterion function with respect to To find the extreme value, the PPD estimation algorithm is as follows: （5） In the formula, It is the added step size factor that estimates the PPD. As The output.

6. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 5, characterized in that, The specific method for setting the system input frequency control criterion function and calculating the system input frequency parameters through the function is as follows: Based on the compact-format dynamic linearized data model, the system input frequency control criterion function is given as follows: （6） Here, λ>0 is a weighting factor used to penalize excessively large changes in the control input. for The desired output voltage of the system at any given time, for Taking the derivative and setting it equal to zero, we get: （7） In the formula, the step size factor Step size factor The addition of this makes the control algorithm more general.

7. The frequency conversion control method for a wireless power transfer system based on model-free adaptive control as described in claim 6, characterized in that, The specific steps for controlling the input frequency of the system using a system frequency converter based on tight-form dynamic linearized model-free adaptive control are as follows: S2.1: Current data collection of wireless power transmission system Output voltage at time and Output voltage at time and the current Input frequency of the time system and Input frequency of the time system ,as well as The expected output voltage of the system at any time ; S2.2: Based on the system's compact-format dynamic linearization data model calculate The theoretical value of the system output voltage at any given time : （8）； S2.3: Based on the PPD estimation algorithm... The pseudo-block Jacobian matrix of the system at time step Perform calculations and based on and The expected output voltage of the system at any time Theoretical value of voltage ,right The frequency of the system is calculated at any time, and the frequency of the inverter is controlled based on the calculation results.

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