Wireless power transmission control method and system based on adaptive impedance matching

Abstract

The invention discloses a wireless power transmission control method and system based on adaptive impedance matching, and relates to the field of power electronics, an adaptive impedance matching module is introduced into an inverter control loop, the equivalent output impedance characteristic of the system is optimized, and the adaptation of the wireless power transmission system to a load is realized. Therefore, the maximum-efficiency electric energy transmission is achieved. Meanwhile, in consideration of load fluctuation and change as well as system equivalent output impedance and load equivalent impedance change, a self-adaptive method for dynamically tracking the maximum output power of the wireless power transmission system is provided to improve the adaptive capacity and load matching accuracy of the constructed impedance matching module. The problem that the transmission efficiency is low due to the fact that a traditional S-S type wireless electric energy transmission system is insufficient in adaptive capacity to loads is solved, meanwhile, the dynamic adaptive capacity to coil offset is achieved, the electric energy transmission efficiency of the system is improved, and meanwhile the control scheme is convenient to achieve and apply practically.

Description

Technical Field

[0001] The present invention relates to the field of power electronics, and particularly to a wireless power transmission control method and system based on adaptive impedance matching. Background Art

[0002] In order to meet the growing demand of loads for high-performance and small-sized power supply systems, the magnetic coupling wireless power transmission technology has received increasing attention from all walks of life. Among various wireless power transmission system structures, the S-S type wireless power transmission structure has been widely used in actual load power supply due to its high anti-interference characteristics and simple structure. However, the S-S type wireless power transmission system still has problems such as poor anti-coil offset ability and low transmission efficiency in actual power supply. Therefore, considering the importance of transmission efficiency in the wireless power transmission system, in order to improve the performance of the S-S type wireless power transmission system in actual applications, it is necessary to conduct a comprehensive and in-depth study on enhancing the transmission efficiency of the system.

[0003] Currently, the research on the maximum efficiency transmission of the S-S type wireless power transmission system mainly falls into two categories: adjusting the coil structure of the wireless power coupling mechanism and load equivalent impedance matching. Optimizing the coil of the wireless power transmission coupling mechanism within the system can effectively enhance the anti-coil position offset ability of the system under certain conditions and improve the transmission efficiency. However, in order to ensure the high-efficiency transmission of electric energy, the system efficiency improvement scheme in such a scheme requires complex hardware structure adjustment and optimization. The passive impedance matching in the load equivalent impedance matching is complex and has large losses. Therefore, the active impedance matching mainly carried out by a DC / DC converter is currently used. However, the introduction of the DC / DC conversion part will not only bring additional harmonics to the load but also increase the system construction cost. Therefore, there is still a large room for improvement in the effectiveness and applicability of the existing system efficiency improvement schemes and technologies for the S-S type wireless power transmission system. Summary of the Invention

[0004] The purpose of the present invention is to address the above deficiencies of the existing technologies. The present invention provides a wireless power transmission control method and system based on adaptive impedance matching, which optimizes the transmission system of the S-S type wireless power transmission system using the impedance matching principle, and can ensure the tracking of the maximum power transmission efficiency of the system in different scenarios while maintaining the simplicity of the system structure.

[0005] A wireless power transmission control method based on adaptive impedance matching, characterized by comprising the following steps:

[0006] Step S1, by establishing an equivalent impedance model of the S-S type wireless power transmission system, determining the equivalent output impedance characteristic function of the S-S type wireless power transmission system;

[0007] Step S2: Determine the parameters of the introduced adaptive impedance matching module according to the specific loop parameters of the S-S type wireless power transfer system;

[0008] Step S3: Establish an impedance matching adaptation method to optimize the parameters and achieve the tracking of the maximum power transfer efficiency of the system.

[0009] Further, in the step S1, by establishing an equivalent impedance model of the S-S type wireless power transfer system, determine the equivalent output impedance function of the S-S type wireless power transfer system, and the equivalent output impedance Z inv (s):

[0010]

[0011] where, R p is the primary side resistance, L p is the primary side inductance, C p is the primary side capacitance, R s is the secondary side resistance, L s is the primary-secondary inductance, C s is the secondary side capacitance, R s is the load equivalent impedance, L f is the series inductance between the rectifier and the load, C f is the parallel capacitance between the rectifier and the load, k inv and k con respectively represent the voltage conversion ratios of the primary inverter and the secondary rectifier, k is the coupling coefficient of the wireless power transfer part, G d (s) is the digital control system delay, G c (s) is the transfer function of the controller module.

[0012] Further, in the step S2, based on the equivalent output impedance function of the S-S type wireless power transfer system and the specific loop parameters of the system, use the transfer function G ir (s) in the introduced adaptive impedance matching module and the relationship analysis of the equivalent output impedance Z inv_i (s) of the S-S type wireless power transfer system optimized by the adaptive impedance matching module to determine the parameter values of the transfer function G ir (s) in the adaptive impedance matching module and the optimized equivalent output impedance Z inv_i (s) of the S-S type wireless power transfer system; The functional relationship between G ir (s) and Z inv_i (s) is:

[0013]

[0014] where, Z p(s) is the equivalent impedance on the primary side of the wireless power transfer part, G i (s) is the influence function of the DC output current on the load side on the AC input of the converter on the secondary side of the wireless power transfer part.

[0015] Furthermore, in the step S3, the specific steps of the impedance matching adaptation method are as follows:

[0016] Step S3-1: Obtain the parameter a(k - 1) of the adaptive impedance matching module at the (k - 1)th moment, and the system output power parameters at the kth, (k - 1)th, and (k - 2)th moments: P o (k), P o (k - 1), P o (k - 2), and proceed to step S3-2;

[0017] Step S3-2: Calculate the change in the output power of the S-S type wireless power transfer system at the (k - 1)th and kth moments, ΔP o (k) and ΔP o (k - 1), and the absolute value abs[ΔP o (k)], and proceed to step S3-3; o (k)] and proceed to step S3-3;

[0018] Step S3-3: Define condition 1: abs[ΔP o (k)] is less than the set value δ. If condition 1 is satisfied, the loop ends. If condition 1 is not satisfied, proceed to step S3-4;

[0019] Step S3-4: Define condition 2: The product of ΔP o (k) and ΔP o (k - 1) is positive. Define condition 3: The product of ΔP o (k) and ΔP o (k - 1) is negative and ΔP o (k - 1) is negative. If any one or more of the above conditions 2 and 3 are satisfied, increase a(k - 1) by the change step size ε to obtain a(k) and return to step S3-1; if neither of the above two conditions is satisfied, proceed to step S3-5;

[0020] Step S3-5: Define condition 4: The product of ΔP o (k) and ΔP o (k - 1) is negative. Define condition 5: ΔP o (k - 1) is positive. Define condition 6: The absolute value of ΔP o is greater than the natural constant e. If the above conditions 4, 5, and 6 are satisfied simultaneously, decrease a(k - 1) by the change step size ε to obtain a(k) and return to step S3-1; if the above three conditions cannot be satisfied simultaneously, directly return to step S3-1.

[0021] Further, in step S3, by combining with the equivalent impedance model of the S-S type wireless power transmission system, the relational expression of the system output power function is obtained as follows:

[0022]

[0023] where V o_ref is the reference value of the DC voltage output on the load side.

[0024] Further, in step S3, the parameters are optimized so that the real part Re[Z inv_i (s)] of the equivalent output impedance Z of the optimized S-S type wireless power transmission system is equal to the load equivalent resistance R inv_i , and at this time, the system output power P L is the maximum, realizing the tracking of the maximum power transmission efficiency of the system. o

[0025] In addition, the embodiment of the present invention also provides a wireless power transmission system based on adaptive impedance matching. The wireless power transmission system based on adaptive impedance matching includes:

[0026] An inverter module for converting a DC power supply into alternating current with a specific frequency required for wireless power transmission;

[0027] A rectifier module for converting the alternating current in the receiving part of wireless power transmission into direct current required by the load;

[0028] A load module for equivalent output characteristics of the actually connected load;

[0029] An SPWM modulation module for controlling the power electronic switches in the inverter module;

[0030] A controller module for giving the SPWM modulation control signal of the inverter;

[0031] An adaptive impedance matching module for optimizing the equivalent output impedance characteristics of the wireless power transmission system and realizing the adaptation of the wireless power transmission system to the load.

[0032] Compared with the prior art, the present invention can achieve the following beneficial effects:

[0033] 1. A wireless power transmission control method and system based on adaptive impedance matching proposed by the present invention optimizes the equivalent output impedance characteristics of the system by introducing an adaptive impedance matching module, realizes the adaptation of the wireless power transmission system to the load, and achieves the tracking of its maximum power transmission efficiency.

[0034] ​2. The wireless power transfer control method and system based on adaptive impedance matching proposed by the present invention have the dynamic adaptation ability to coil offset.

[0035] 3. The control structure of the wireless power transfer control method and system based on adaptive impedance matching proposed by the present invention is simple, the cost is low, and it has high feasibility and practicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a flowchart of a wireless power transfer control method based on adaptive impedance matching proposed by the present invention.

[0037] Figure 2 It is an adaptive method for impedance matching proposed by the present invention.

[0038] Figure 3 It is a main structure topology diagram of an S-S type wireless power transfer system based on adaptive impedance matching proposed by the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0039] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] Combined with Figure 1 , a wireless power transfer control method based on adaptive impedance matching, characterized by comprising the following steps:

[0041] Step S1: By establishing an equivalent impedance model of the S-S type wireless power transfer system, determine the equivalent output impedance characteristic function of the S-S type wireless power transfer system;

[0042] Step S2: According to the specific loop parameters of the S-S type wireless power transfer system, determine the parameters of the introduced adaptive impedance matching module;

[0043] Step S3: Establish an adaptive method for impedance matching, optimize the parameters, and achieve the tracking of the maximum power transmission efficiency of the system.

[0044] Further, in the step S1, by establishing an equivalent impedance model of the S-S type wireless power transfer system, determine the equivalent output impedance function of the S-S type wireless power transfer system, and the equivalent output impedance Z inv (s):

[0045]

[0046] Among them, R p is the primary-side resistance, L p is the primary-side inductance, C p is the primary-side capacitance, R s is the secondary-side resistance, L s is the primary-secondary inductance, C s is the secondary-side capacitance, R s is the load equivalent impedance, L f is the series inductance between the rectifier and the load, C f is the parallel capacitance between the rectifier and the load, k inv and k con respectively represent the voltage conversion ratios of the primary inverter and the secondary rectifier, k is the coupling coefficient of the wireless power transfer part, G d (s) is the delay of the digital control system, G c (s) is the transfer function of the controller module.

[0047] Furthermore, in the step S2, based on the equivalent output impedance function of the S-S type wireless power transfer system and the specific loop parameters of the system, using the transfer function G ir (s) in the introduced adaptive impedance matching module and the relationship analysis of the equivalent output impedance Z inv_i (s) of the S-S type wireless power transfer system optimized by the adaptive impedance matching module, determine the parameter values of the transfer function G ir (s) in the adaptive impedance matching module and the equivalent output impedance Z inv_i (s) after optimization; the function relationship between G ir (s) and Z inv_i (s) is:

[0048]

[0049] Among them, Z p (s) is the equivalent impedance of the primary side of the wireless power transfer part, G i (s) is the influence function of the DC output current on the load side on the AC input of the secondary side converter of the wireless power transfer part.

[0050] Furthermore, combined with Figure 2 , in the step S3, the specific steps of the impedance matching adaptive method are as follows:

[0051] Step S3-1: Obtain the parameters a(k - 1) of the adaptive impedance matching module at the k - 1 moment, and the system output power parameters at the k, k - 1, and k - 2 moments: P o (k), P o (k - 1), P o(k - 2), proceed to step S3-2;

[0052] Step S3-2, calculate the change in output power ΔP of the S-S type wireless power transfer system at time k - 1 and time k o (k) and ΔP o (k - 1), and ΔP o (k) of the absolute value abs[ΔP o (k)], proceed to step S3-3;

[0053] Step S3-3, define condition 1: abs[ΔP o (k)] is less than the set value δ. If condition 1 is satisfied, the loop ends. If condition 1 is not satisfied, proceed to step S3-4;

[0054] Step S3-4, define condition 2: the product of ΔP o (k) and ΔP o (k - 1) is positive, define condition 3: the product of ΔP o (k) and ΔP o (k - 1) is negative and ΔP o (k - 1) is negative. If any one or more of the above conditions 2 and condition 3 are satisfied, increase a(k - 1) by the change step size ε to obtain a(k) and return to step S3-1; if neither of the above two conditions is satisfied, proceed to step S3-5;

[0055] Step S3-5, define condition 4: the product of ΔP o (k) and ΔP o (k - 1) is negative, define condition 5: ΔP o (k - 1) is positive, define condition 6: the absolute value of ΔP o is greater than the natural constant e. If the above conditions 4, condition 5, and condition 6 are simultaneously satisfied, decrease a(k - 1) by the change step size ε to obtain a(k) and return to step S3-1; if the above three conditions cannot be simultaneously satisfied, directly return to step S3-1.

[0056] Furthermore, in the said step S3, combining with the equivalent impedance model of the S-S type wireless power transfer system, the system output power function relational expression is obtained as:

[0057]

[0058] Among them, V o_ref is the reference value of the DC voltage output on the load side.

[0059] Furthermore, in the said step S3, optimize the parameters so that after optimization, the real part Re[Z inv_i of the equivalent output impedance Z of the S-S type wireless power transfer system inv_i(s) is equal to the load equivalent resistance R L , at this time, the system output power P o is the largest, achieving the tracking of the maximum electric energy transmission efficiency of the system.

[0060] Combined with Figure 3 , an embodiment of the present invention further provides a wireless power transmission system based on adaptive impedance matching. The wireless power transmission system based on adaptive impedance matching includes:

[0061] An inverter module, which is used to convert a DC power supply into an alternating current with a specific frequency required for wireless power transmission;

[0062] A rectifier module, which is used to convert the alternating current in the receiving part of wireless power transmission into direct current required by the load;

[0063] A load module, which is used to equivalently represent the output characteristics of the actually connected load;

[0064] An SPWM modulation module, which is used to control the power electronic switches in the inverter module;

[0065] A controller module, which is used to give the SPWM modulation control signal for the inverter;

[0066] An adaptive impedance matching module, which is used to optimize the equivalent output impedance characteristics of the wireless power transmission system and realize the adaptation of the wireless power transmission system to the load.

[0067] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A wireless power transfer control method based on adaptive impedance matching, characterized in that Including the following steps: Step S1: By establishing an equivalent impedance model of the S-S type wireless power transfer system, determine the equivalent output impedance characteristic function of the S-S type wireless power transfer system; Step S2: According to the specific loop parameters of the S-S type wireless power transfer system, determine the parameters of the introduced adaptive impedance matching module; Step S3: Establish an impedance matching self-adaptive method, optimize the parameters, and achieve the tracking of the maximum power transmission efficiency of the system.

2. The wireless power transmission control method based on adaptive impedance matching according to claim 1, wherein: In the step S1, by establishing an equivalent impedance model of the S-S type wireless power transmission system, the equivalent output impedance function of the S-S type wireless power transmission system is determined, and the equivalent output impedance Z inv (s): Among them, R p is the primary side resistance, L p is the primary side inductance, C p is the primary side capacitance, R s is the secondary side resistance, L s is the primary-secondary inductance, C s is the secondary side capacitance, R s is the load equivalent impedance, L f is the series inductance between the rectifier and the load, C f is the parallel capacitance between the rectifier and the load, k inv and k con respectively represent the voltage conversion ratios of the primary side inverter and the secondary side rectifier. k is the partial coupling coefficient of the wireless power transfer. G d (s) is the digital control system delay, G c (s) is the transfer function of the controller module.

3. A wireless power transfer control method based on adaptive impedance matching according to claim 1, characterized in that: In the step S2, based on the equivalent output impedance function of the S-S type wireless power transfer system and the specific loop parameters of the system, the transfer function G ir in the introduced adaptive impedance matching module is analyzed with the equivalent output impedance Z inv_i (s) of the S-S type wireless power transfer system optimized by the adaptive impedance matching module, and the parameter values of the transfer function G ir (s) and the equivalent output impedance Z inv_i (s) of the optimized S-S type wireless power transfer system are determined; the functional relationship between G ir (s) and Z inv_i (s) is: Among them, Z p (s) is the equivalent impedance of the primary side of the wireless power transfer part, and G i (s) is the influence function of the DC output current on the load side on the AC input of the secondary side converter of the wireless power transfer part.

4. The wireless power transmission control method based on adaptive impedance matching according to claim 1, wherein: In the said Step S3, the specific steps of the impedance matching self-adaptive method are as follows: Step S3-1: Obtain the adaptive impedance matching module parameter a(k-1) at time k-1, and the system output power parameters at times k, k-1, and k-2: P o (k), P o (k-1), P o (k-2), and proceed to Step S3-2; Step S3-2: Calculate the change in output power ΔP of the S-S type wireless power transmission system at time k-1 and time k o (k) and ΔP o (k-1), and ΔP o (k), the absolute value abs[ΔP o (k)], and proceed to step S3-3; Step S3-3, define Condition 1: abs[ΔP o (k)] is less than the set value δ. If Condition 1 is satisfied, the loop ends; if not, proceed to Step S3-4; Step S3-4, Define Condition 2: ΔP o (k) and the product of ΔP o (k - 1) is positive, Define Condition 3: ΔP o (k) and the product of ΔP o (k - 1) is negative and ΔP o (k - 1) is negative. If any one or more of the above Condition 2 and Condition 3 are satisfied, then increase a(k - 1) by the change step size ε to obtain a(k) and return to Step S3-1; if neither of the above two conditions is satisfied, then proceed to Step S3-5; Step S3-5, Define Condition 4: ΔP o (k) and the product of ΔP o (k - 1) is negative, Define Condition 5: ΔP o (k - 1) is positive, Define Condition 6: the absolute value of ΔP o is greater than the natural constant e. If the above Conditions 4, 5, and 6 are all satisfied simultaneously, then reduce a(k - 1) by the change step ε to obtain a(k) and return to Step S3-1; if the above three conditions cannot be satisfied simultaneously, then directly return to Step S3-1.

5. A wireless power transfer control method based on adaptive impedance matching according to claim 1, characterized in that: In the said Step S3, combining with the equivalent impedance model of the S-S type wireless power transfer system, the system output power function relationship is obtained as: Among them, V o_ref is the reference value of the DC voltage output on the load side.

6. The wireless power transfer control method based on adaptive impedance matching according to claim 1, characterized in that: In the step S3, the parameters are optimized so that the equivalent output impedance Z of the optimized S-S type wireless power transmission system inv_i The real part Re[Z inv_i (s)] is equal to the equivalent resistance R of the load L , and at this time, the output power P of the system o is the maximum, realizing the tracking of the maximum power transmission efficiency of the system.

7. A wireless power transmission system based on adaptive impedance matching, characterized in that, The wireless power transfer system based on adaptive impedance matching is applied to a wireless power transfer control method based on adaptive impedance matching as described in any one of claims 1-6. The wireless power transfer system based on adaptive impedance matching includes: An inverter module, used to convert a DC power supply into specific frequency alternating current required for wireless power transfer; A rectifier module, used to convert the alternating current in the receiving part of wireless power transfer into direct current required by the load; A load module, used to equivalent the output characteristics of the actually connected load; An SPWM modulation module, used to control the power electronic switches in the inverter module; A controller module, used to give the SPWM modulation control signal for the inverter; An adaptive impedance matching module, used to optimize the equivalent output impedance characteristics of the wireless power transfer system and achieve the adaptation of the wireless power transfer system to the load.

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