Wireless power transfer circuit, system, and method of combating parameter drift

Abstract

The application provides a wireless power transmission circuit, a system and a parameter offset resisting method, the wireless power transmission circuit comprises a direct current voltage source, a primary side circuit and a secondary side circuit which are coupled, the primary side circuit comprises an inverter bridge circuit, an automatic tuning auxiliary circuit, a primary side compensation capacitor and a primary side inductor; the application adjusts the working frequency of the secondary side circuit based on the inverter bridge circuit first, so that the secondary side circuit works at the resonant frequency, then the automatic tuning auxiliary circuit is used for voltage compensation of the primary side compensation capacitor and the primary side inductor, so that the secondary side current of the secondary side circuit remains constant, and then the transmission efficiency and power of the wireless power transmission system remain unchanged when one or more parameters of the wireless power transmission circuit in the primary side circuit and the secondary side circuit change.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission technology, specifically to a wireless power transmission circuit, system, and method for resisting parameter offset. Background Technology

[0002] Electricity is closely related to our lives. From small mobile phones to various industrial equipment, everything requires electricity. When talking about electricity and electrical equipment, we cannot ignore the topic of charging. Currently, there are two types of charging: wired charging and wireless charging. Wired charging is still the main method. However, in recent years, wireless charging has received widespread attention because it does not require an external charging cable and has the characteristics of safety, reliability, convenience, flexibility, and strong environmental adaptability.

[0003] In wireless power transmission systems, efficiency and power are two very important indicators. Specifically, the system needs to provide the power required by the device being charged, and it needs to ensure maximum efficiency during the charging process to reduce energy loss. However, in actual circuits, due to various factors, the above state is often not achieved. For example, the parameters of system components will inevitably deviate due to component aging during circuit operation. Parameter deviation will lead to reduced power transmission efficiency and power reduction. Summary of the Invention

[0004] In view of this, it is necessary to provide a wireless power transmission circuit, system and anti-parameter offset method to solve the technical problem of reduced power transmission efficiency and power reduction caused by device parameter offset in wireless power transmission.

[0005] To achieve the above objectives, on the one hand, the present invention provides a wireless power transmission circuit, including a DC voltage source, a primary-side circuit and a secondary-side circuit coupled together, wherein the primary-side circuit includes an inverter bridge circuit, an automatic tuning auxiliary circuit, a primary-side compensation capacitor and a primary-side inductor.

[0006] The DC voltage source is connected to the inverter bridge circuit. The positive output terminal of the inverter bridge circuit is connected to the input terminal of the automatic tuning auxiliary circuit. The output terminal of the automatic tuning auxiliary circuit is connected to the first terminal of the primary-side compensation capacitor. The second terminal of the primary-side compensation capacitor is connected to the first terminal of the primary-side inductor. The second terminal of the primary-side inductor is connected to the negative output terminal of the inverter bridge circuit. The inverter bridge circuit and the automatic tuning auxiliary circuit are respectively connected to an external controller.

[0007] Specifically, the switching frequency of the inverter bridge circuit is adjusted based on the control signal transmitted by the external controller, so that the operating frequency of the secondary circuit is the resonant frequency. Then, the voltage compensation of the primary compensation capacitor and the primary inductor is performed by the automatic tuning auxiliary circuit to keep the secondary current of the secondary circuit constant.

[0008] Optionally, the inverter bridge circuit includes a first switch, a second switch, a third switch, and a fourth switch;

[0009] The drains of the first and second switching transistors are connected to the positive output terminal of the DC voltage source. The source of the first switching transistor is connected to the drain of the third switching transistor and the input terminal of the automatic tuning auxiliary circuit. The source of the second switching transistor is connected to the drain of the fourth switching transistor and the second terminal of the primary inductor. The sources of the third and fourth switching transistors are connected to the negative output terminal of the DC voltage source. The gates of the first, second, third, and fourth switching transistors are connected to the external controller.

[0010] Optionally, the automatic tuning auxiliary circuit includes a fifth switching transistor, a sixth switching transistor, and an adjusting capacitor;

[0011] The source of the fifth switch and the drain of the sixth switch are connected to the positive output terminal of the inverter bridge circuit. The drain of the fifth switch is connected to the first terminal of the regulating capacitor. The second terminal of the regulating capacitor is connected to the source of the sixth switch and the first terminal of the primary-side compensation capacitor. The gates of the fifth switch and the sixth switch are connected to the external controller.

[0012] Optionally, the secondary circuit includes a secondary inductor, a secondary compensation capacitor, a rectifier circuit, a filter capacitor, and a load;

[0013] Wherein, the first end of the secondary inductor is connected to the first end of the secondary compensation capacitor, the second end of the secondary inductor is connected to the positive input terminal of the rectifier circuit, the second end of the secondary compensation capacitor is connected to the negative input terminal of the rectifier circuit, the positive output terminal of the rectifier circuit is connected to the first end of the filter capacitor and the first end of the load, and the negative output terminal of the rectifier circuit is connected to the second end of the filter capacitor and the second end of the load.

[0014] Optionally, the rectifier circuit includes a first diode, a second diode, a third diode, and a fourth diode;

[0015] In this configuration, the anode of the first diode is connected to the second terminal of the secondary compensation capacitor and the cathode of the third diode; the cathode of the first diode is connected to the cathode of the second diode and the first terminal of the filter capacitor; the anode of the second diode is connected to the cathode of the fourth diode and the second terminal of the secondary inductor; and the anodes of the third and fourth diodes are connected to the second terminal of the filter capacitor.

[0016] Furthermore, the present invention also provides a wireless power transmission system, including a wireless power transmission circuit, a controller, and a sampling device, wherein the wireless power transmission circuit is the wireless power transmission circuit described above.

[0017] The sampling device is installed in the wireless power transmission circuit and is used to detect the voltage and current data in the wireless power transmission circuit and transmit it to the controller in real time. The controller is used to control the inverter bridge circuit and the automatic tuning auxiliary circuit in the wireless power transmission circuit according to the voltage and current data, so that the primary circuit and the secondary circuit in the wireless power transmission circuit both operate at the resonant frequency.

[0018] Furthermore, the present invention also provides a method for resisting parameter offset, applicable to the aforementioned wireless power transmission circuit; the method for resisting parameter offset includes:

[0019] Obtain the primary and secondary side parameters of the wireless power transmission circuit;

[0020] The current secondary resonant frequency is calculated based on the primary and secondary parameters.

[0021] Adjust the operating frequency of the wireless power transmission circuit to the current secondary resonant frequency;

[0022] The primary input voltage of the wireless power transfer circuit is adjusted according to the current secondary resonant frequency to keep the secondary current of the wireless power transfer circuit constant.

[0023] Optionally, the primary and secondary side parameters include first primary and secondary side parameters and second primary and secondary side parameters; obtaining the primary and secondary side parameters of the wireless power transmission circuit includes:

[0024] Obtain the first primary and secondary side parameters of the wireless power transmission circuit at the first operating frequency;

[0025] The operating frequency of the wireless power transmission circuit is switched to the second operating frequency, and the second primary and secondary side parameters are obtained.

[0026] Optionally, calculating the current secondary resonant frequency based on the primary and secondary parameters includes:

[0027] Substitute the first primary and secondary side parameters and the second primary and secondary side parameters into the preset secondary side LC calculation formula to obtain the first secondary side LC equation and the second secondary side LC equation.

[0028] Construct a set of secondary side LC equations based on the first secondary side LC equation and the second secondary side LC equation, and solve them to obtain the current secondary side inductance value and the current secondary side compensation capacitor value.

[0029] The current secondary resonant frequency is calculated based on the current secondary inductance value and the current secondary compensation capacitor value.

[0030] Optionally, adjusting the primary-side input voltage of the wireless power transfer circuit according to the current secondary-side resonant frequency to keep the secondary-side current of the wireless power transfer circuit constant includes:

[0031] The inverter drive phase of the inverter bridge circuit in the wireless power transmission circuit is obtained by calculating based on the current secondary resonant frequency.

[0032] The current voltage drive phase of the automatic tuning auxiliary circuit in the wireless power transmission circuit is calculated based on the inverter drive phase.

[0033] Based on the current voltage driving phase, the automatic tuning auxiliary circuit adjusts the primary input voltage to keep the secondary current of the wireless power transfer circuit constant.

[0034] The beneficial effects of this invention are as follows: This invention provides a wireless power transmission circuit, including a DC voltage source, a primary circuit and a secondary circuit coupled together. The primary circuit includes an inverter bridge circuit, an automatic tuning auxiliary circuit, a primary compensation capacitor, and a primary inductor. This invention first adjusts the operating frequency of the secondary circuit based on the inverter bridge circuit, so that the secondary circuit operates at the resonant frequency. Then, the voltage of the primary compensation capacitor and the primary inductor is compensated by the automatic tuning auxiliary circuit, so that the secondary current of the secondary circuit remains constant. This ensures that the transmission efficiency and power of the wireless power transmission system remain unchanged when one or more parameters in the primary and secondary circuits change. Attached Figure Description

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 A schematic diagram of an embodiment of the wireless power transmission circuit provided by the present invention;

[0037] Figure 2 Equivalent circuit diagram of the wireless power transmission circuit provided by the present invention;

[0038] Figure 3 This is a flowchart illustrating an embodiment of the anti-parameter offset method provided by the present invention;

[0039] Figure 4A simulation diagram of the secondary circuit in the simulation circuit of the wireless power transmission circuit provided by the present invention;

[0040] Figure 5 Simulation diagram of the primary-side circuit in the simulation circuit of the wireless power transfer circuit provided by the present invention.

[0041] Figure 6 A schematic diagram of the switching transistor drive signal in the simulation circuit of the wireless power transmission circuit provided by the present invention;

[0042] Figure 7 The waveform diagram of the secondary current when the primary and secondary side parameters are offset, as provided by the present invention. Detailed Implementation

[0043] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0044] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may be implemented out of order, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts. Some block diagrams shown in the drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities may be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0045] The terms "first," "second," etc., used in the embodiments of this invention are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a technical feature defined with "first" or "second" may explicitly or implicitly include at least one of those features.

[0046] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a mutually exclusive, independent, or alternative embodiment. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0047] This invention provides a wireless power transmission circuit, system, and method for resisting parameter offset, which will be described below.

[0048] Figure 1 This is a schematic diagram of an embodiment of the wireless power transmission circuit provided by the present invention, as shown below. Figure 1 As shown, the wireless power transmission circuit includes a DC voltage source U. in The primary circuit 10 and the secondary circuit 20 are coupled together. The primary circuit 10 includes an inverter bridge circuit 11, an automatic tuning auxiliary circuit 12, and a primary compensation capacitor C. p and primary inductor L p ;

[0049] Among them, DC voltage source U in The inverter bridge circuit 11 is connected to the inverter bridge circuit 11. The positive output terminal of the inverter bridge circuit 11 is connected to the input terminal of the automatic tuning auxiliary circuit 12. The output terminal of the automatic tuning auxiliary circuit 12 is connected to the primary-side compensation capacitor C. p The first terminal is connected to the primary-side compensation capacitor C. p The second terminal is connected to the first terminal of the primary inductor, and the primary inductor L p The second terminal is connected to the negative output terminal of the inverter bridge circuit 11, and the inverter bridge circuit 11 and the automatic tuning auxiliary circuit 12 are respectively connected to the external controller.

[0050] Specifically, the switching frequency of the inverter bridge circuit 11 is adjusted based on the control signal transmitted by the external controller, so that the operating frequency of the secondary circuit 20 is the resonant frequency. Then, the primary side compensation capacitor C is adjusted by the automatic tuning auxiliary circuit 12. p and primary inductor L p Voltage compensation is performed to keep the secondary current I2 of the secondary circuit 20 constant.

[0051] Understandably, a wireless power transfer system generally includes a primary side, a secondary side, and a coupling coil. The primary side includes the input power supply and a compensation network composed of inductors and capacitors, while the secondary side includes the compensation network and the load. The compensation network exists on both the primary and secondary sides and has a significant impact on circuit performance. Ideally, when the operating frequency of the wireless power transfer system is at the resonant frequency, zero-phase output and constant current output can be achieved. However, in practical applications, due to manufacturing processes or component aging, the component parameters on the primary and secondary sides of the wireless power transfer system may shift, causing the system to not always be in a resonant state. This leads to a decrease in system performance and energy waste. This invention adjusts the operating frequency of the system through an inverter bridge circuit, enabling the secondary circuit to operate at the required resonant frequency. Then, the automatic tuning auxiliary circuit 12 adjusts the input voltage to compensate for the reactive portion of the input voltage, ensuring that the input voltage and input current are in phase, thereby keeping the secondary current constant.

[0052] It should be noted that, in this embodiment of the invention, for the wireless power transmission system, the following voltage loop expression can be established based on the primary voltage loop and the secondary voltage loop:

[0053]

[0054] Among them, V s I1 represents the primary current, I2 represents the secondary current, and Z represents the input voltage. p Z represents the primary impedance. s Z represents the secondary impedance. M Z represents mutual inductance impedance. p Z s Z M The expression is as follows:

[0055]

[0056] In the formula, L p C represents the primary coil inductance (i.e., the primary inductance). p L represents the primary-side compensation capacitor. s C represents the secondary coil inductance (i.e., the secondary inductance). s This represents the secondary-side compensation capacitor. Substituting the impedance expression above into the voltage loop expression, we can obtain the secondary-side current expression:

[0057]

[0058] As can be seen from the expression for the secondary current, R eq For the equivalent load of the subsequent stage, in Z p When the value is zero (i.e., primary-side resonance), the equation can be simplified to the following:

[0059]

[0060] As can be seen from the simplified formula for the secondary current above, at primary resonance, the secondary current I2 is only related to the input voltage V. s The output current is related to the load but not to the load, exhibiting constant current output characteristics. When the primary side is not resonant, the output current will be affected by load changes. Therefore, to achieve constant output, primary side compensation is required when the primary side is not resonant (i.e., the primary side parameters are offset). This invention uses an automatic tuning auxiliary circuit 12 to perform reactive power compensation on the primary side circuit 10, thereby solving the problem of primary side parameter offset. The secondary side parameter offset can be solved by monitoring the current and voltage parameters through an external controller, thereby calculating the secondary side resonant frequency, and achieving secondary side circuit resonance by frequency tuning of the secondary side circuit 20, thus solving the problem of secondary side parameter offset.

[0061] Compared with the prior art, the present invention provides a wireless power transmission circuit, with a DC voltage source U in The primary circuit 10 and the secondary circuit 20 are coupled together. The primary circuit 10 includes an inverter bridge circuit 11, an automatic tuning auxiliary circuit 12, and a primary compensation capacitor C. p and primary inductor L p The present invention first adjusts the operating frequency of the secondary circuit 20 based on the inverter bridge circuit 11, so that the secondary circuit 20 operates at the resonant frequency, and then adjusts the primary side compensation capacitor C through the automatic tuning auxiliary circuit 12. p and primary inductor L p Voltage compensation is performed to keep the secondary current I2 of the secondary circuit 20 constant, thereby ensuring that the transmission efficiency and power of the wireless power transmission system remain unchanged when one or more parameters in the primary circuit 10 and the secondary circuit 20 change.

[0062] In some embodiments of the present invention, the inverter bridge circuit 11 includes a first switch Q1, a second switch Q2, a third switch Q3, and a fourth switch Q4;

[0063] Among them, the drain of the first switching transistor Q1 and the drain of the second switching transistor Q2 are connected to the DC voltage source U. in The positive output terminal is connected, the source of the first switching transistor Q1 is connected to the drain of the third switching transistor Q3 and the input terminal of the automatic tuning auxiliary circuit 12, and the source of the second switching transistor Q2 is connected to the drain of the fourth switching transistor Q4 and the primary inductor L. p The second terminal is connected to the source of the third switch Q3 and the source of the fourth switch Q4, which are connected to the DC voltage source U. in The negative output terminal is connected, and the gates of the first switch Q1, the second switch Q2, the third switch Q3, and the fourth switch Q4 are connected to the external controller.

[0064] It should be noted that, in this embodiment of the invention, the inverter bridge circuit 11 is a full-bridge inverter circuit composed of four NMOS transistors, used to input the DC voltage source U. in The DC power is converted into AC power, and the gates of the four switching transistors are controlled by an external controller so that the frequency of the output voltage of the inverter bridge circuit is the resonant frequency of the secondary circuit 20.

[0065] In some embodiments of the present invention, the automatic tuning auxiliary circuit 12 includes a fifth switch Q5, a sixth switch Q6, and an adjustment capacitor C. A ;

[0066] In this circuit, the source of the fifth switch Q5 and the drain of the sixth switch Q6 are connected to the positive output terminal of the inverter bridge circuit 11, and the drain of the fifth switch Q5 is connected to the regulating capacitor C. A Connect the first terminal and adjust the capacitor C. A The second terminal is connected to the source and primary side compensation capacitor C of the sixth switch Q6. p The first terminal is connected, and the gates of the fifth switch Q5 and the sixth switch Q6 are connected to the external controller.

[0067] It is understood that in this embodiment of the invention, both the fifth switch Q5 and the sixth switch Q6 are NMOS transistors, and the gate drive signals of the fifth switch Q5 and the sixth switch Q6 are 90° out of phase with the drive signals of the switches in the inverter bridge circuit 11. When the wireless power transmission circuit is working, when the fifth switch Q5 is turned on, the sixth switch Q6 is turned off, and the adjusting capacitor C... A Charging; when the fifth switch Q5 is off and the sixth switch Q6 is on, adjust capacitor C. A Discharge occurs because of the presence of passive components in the circuit and the different phases of the voltage and current output by the inverter bridge circuit 11. Therefore, when adjusting capacitor C... A During one charge / discharge cycle, the adjusting capacitor C A The charging and discharging charges are different, so the capacitor C is adjusted. A The absolute value of the voltage continuously increases. During this period, due to the characteristics of the capacitor, the phase of the input current is adjusted during the charging and discharging of the regulating capacitor. When the circuit reaches steady state, the regulating capacitor C... A When the charging and discharging reach dynamic equilibrium, the voltage and current output by the automatic tuning auxiliary circuit 12 are in phase. This means the reactive power in the circuit is compensated by the automatic tuning auxiliary circuit 12. The automatic tuning auxiliary circuit 12 is essentially an auxiliary voltage source that only provides reactive power. For details, please refer to... Figure 2 , Figure 2 V in s V is the input voltage. A It serves as an auxiliary voltage source.

[0068] It should be noted that in the specific implementation, since the body diode of the MOSFET will limit the reverse voltage of the capacitor, the automatic tuning auxiliary circuit 12 can only resist unilateral offset. Therefore, an anti-parallel MOSFET is connected in series with the fifth and sixth switching transistors, and the driving signal of the series MOSFET is consistent with the driving signal of the corresponding fifth switching transistor Q5 or sixth switching transistor Q6.

[0069] In some embodiments of the present invention, the secondary circuit includes a secondary inductor L. s Secondary side compensation capacitor C s rectifier circuit, filter capacitor C1 and load R L ;

[0070] Among them, the secondary inductor L s The first terminal is connected to the first terminal of the secondary compensation capacitor, and the secondary inductance L s The second terminal is connected to the positive input terminal of the rectifier circuit, and the secondary compensation capacitor C s The second terminal is connected to the negative input terminal of the rectifier circuit, and the positive output terminal of the rectifier circuit is connected to the first terminal of the filter capacitor C1 and the load R. L The first terminal is connected to the negative output terminal of the rectifier circuit, and the second terminal of the filter capacitor C1 is connected to the load R. L The second end is connected.

[0071] In some embodiments of the present invention, the rectifier circuit includes a first diode D1, a second diode D2, a third diode D3, and a fourth diode D4;

[0072] Among them, the anode of the first diode D1 and the secondary-side compensation capacitor C s The second terminal of the first diode D1 is connected to the cathode of the third diode D3. The cathode of the first diode D1 is connected to the cathode of the second diode D2 and the first terminal of the filter capacitor C1. The anode of the second diode D2 is connected to the cathode of the fourth diode D4 and the secondary inductor L. s The second terminal is connected, and the anodes of the third diode D3 and the fourth diode D4 are connected to the second terminal of the filter capacitor C1.

[0073] Furthermore, the present invention also provides a wireless power transmission system, including a wireless power transmission circuit, a controller, and a sampling device, wherein the wireless power transmission circuit is the wireless power transmission circuit described above.

[0074] The sampling device is installed in the wireless power transmission circuit to detect the voltage and current data in the wireless power transmission circuit and transmit it to the controller in real time. The controller is used to control the inverter bridge circuit and the automatic tuning auxiliary circuit 12 in the wireless power transmission circuit according to the voltage and current data, so that the primary circuit and the secondary circuit in the wireless power transmission circuit both operate at the resonant frequency.

[0075] It should be noted that the wireless power transmission system provided in this embodiment of the invention is based on the wireless power transmission circuit described above, and also includes the wireless power transmission circuit described above. Its implementation and function are similar to those of the wireless power transmission circuit described above. For specific implementation methods, please refer to the specific embodiments of the wireless power transmission circuit described above, which will not be repeated here.

[0076] To achieve the above objectives, the present invention also provides a method for resisting parameter offset, applicable to the aforementioned wireless power transmission circuit.

[0077] Please refer to Figure 3 Anti-parameter offset methods include:

[0078] Step S301: Obtain the primary and secondary side parameters of the wireless power transmission circuit;

[0079] Step S302: Calculate the current secondary resonant frequency based on the primary and secondary parameters;

[0080] Step S303: Adjust the operating frequency of the wireless power transmission circuit to the current secondary resonant frequency;

[0081] Step S304: Adjust the primary input voltage of the wireless power transfer circuit according to the current secondary resonant frequency so that the secondary current of the wireless power transfer circuit remains constant.

[0082] In some embodiments of the present invention, the primary and secondary edge parameters include a first primary and secondary edge parameter and a second primary and secondary edge parameter, and step S301 includes:

[0083] Obtain the first primary and secondary side parameters of the wireless power transfer circuit at the first operating frequency;

[0084] The operating frequency of the wireless power transmission circuit is switched to the second operating frequency, and the second primary and secondary side parameters are obtained.

[0085] In some embodiments of the present invention, step S302 includes:

[0086] Substitute the first primary and secondary side parameters and the second primary and secondary side parameters into the preset secondary side LC calculation formula to obtain the first secondary side LC equation and the second secondary side LC equation;

[0087] Construct a set of secondary side LC equations based on the first and second secondary side LC equations and solve them to obtain the current secondary side inductance value and the current secondary side compensation capacitor value.

[0088] The current secondary resonant frequency is calculated based on the current secondary inductance and compensation capacitor values.

[0089] In some embodiments of the present invention, step S304 includes:

[0090] The inverter drive phase of the inverter bridge circuit in the wireless power transmission circuit is obtained by calculation based on the current secondary resonant frequency.

[0091] The current voltage drive phase of the automatic tuning auxiliary circuit 12 in the wireless power transmission circuit is calculated based on the inverter drive phase.

[0092] The primary input voltage is adjusted by the current voltage-driven phase-driven automatic tuning auxiliary circuit 12 so that the secondary current of the wireless power transfer circuit remains constant.

[0093] It should be noted that, based on the wireless power transmission circuit, the automatic tuning auxiliary circuit 12 is regarded as an auxiliary power source providing reactive power. Combining the above loop voltage expression and secondary current expression, the following voltage equation can be obtained:

[0094]

[0095] In the above formula, V A This represents the voltage of the equivalent auxiliary voltage source of the automatic tuning auxiliary circuit 12. From the voltage equation, we know that the primary inductance L... p and primary-side compensation capacitor C p It only concerns the imaginary part, and the primary inductance L can be eliminated by compensating only the imaginary part (i.e., only reactive power compensation) through the automatic tuning auxiliary circuit 12. p and primary-side compensation capacitor C p The parameter offset affects the auxiliary voltage source V. A When the input voltage V equals the imaginary part of the voltage equation, the effect of the primary side parameter offset can be completely eliminated. S The relationship between the input voltage V and the primary current lies only in the real part, that is, after reactive power compensation by the automatic tuning auxiliary circuit 12, the input voltage V s It is in phase with the primary current I1; but the secondary inductance L s and secondary side compensation capacitor C s Since the input voltage exists in both the imaginary and real parts, this invention adds frequency modulation control and parameter identification to the wireless power transmission circuit. The current and voltage of the wireless power transmission circuit are monitored using ammeters and voltmeters, and the monitoring data is uploaded to the controller. The primary and secondary side parameters include the monitored primary side current I1 and input voltage V. s Pre-stored downstream load impedance R eq With mutual inductance M, the resonant frequency of the secondary circuit (i.e., the current secondary resonant frequency) can be calculated by adjusting the operating frequency through the primary and secondary side parameters. The controller adjusts the operating frequency to the current secondary resonant frequency by controlling the inverter bridge circuit, thus achieving secondary circuit resonance. Then, the automatic tuning auxiliary circuit 12 performs voltage adjustment and reactive power compensation to ensure that the input voltage V... sIt is in phase with the primary current I1, ensuring that the secondary current I2 remains constant, thus achieving constant current output.

[0096] In practical implementation, assuming that the automatic tuning auxiliary circuit 12 can guarantee compensation for the reactive power, considering only the real part of the above voltage equation, the following equation (i.e., the secondary side LC calculation formula) can be obtained:

[0097]

[0098] By changing the operating frequency, the following system of equations (i.e., the secondary side LC equations) can be obtained:

[0099]

[0100] In the above formula, V s w (1，2) Given a known and controllable first and second operating frequencies (the first primary and secondary side parameters are the parameters at operating frequency ω1, and the second primary and secondary side parameters are the parameters at operating frequency ω2), R eq M is known and assumed to be constant, and I1 can be measured on the original side. Therefore, for the above system of equations, only L... s C s Since there are two unknowns, and therefore two equations with two unknowns, L can be found on the primary side. s C s After calculating the value of the secondary side parameter, we can then use it to... By determining the resonant frequency of the secondary side and then adjusting the system operating frequency to that resonant frequency, the offset resistance of the secondary side parameters is achieved. For the primary side, although changing the offset will affect its resonance, the presence of the automatic tuning auxiliary circuit 12 compensates for the impact of the primary side by adjusting the phase of the drive signal of the switching transistor in the automatic tuning auxiliary circuit 12. Therefore, the method of the present invention achieves offset resistance of the bilateral parameters of the wireless power transmission system.

[0101] It is understandable that frequency conversion will also affect the final constant current output. Therefore, this invention uses an automatic tuning auxiliary circuit 12 to compensate for the impact of frequency conversion on the primary side, so that the system can still maintain constant current output even when the parameters on both sides are offset.

[0102] It should be noted that, in this embodiment of the invention, a simulation circuit was constructed based on the above-described implementation method to verify the feasibility of the bilateral anti-parameter offset method. For details, please refer to... Figure 4 , Figure 5 , Figure 6 and Figure 7 ,in, Figure 4 This is a simulation diagram of the secondary circuit in the simulation circuit of the wireless power transmission circuit provided by the present invention. Figure 5This is a simulation diagram of the primary-side circuit in the simulation circuit of the wireless power transmission circuit provided by the present invention. Figure 6 This is a schematic diagram of the switching transistor drive signal in the simulation circuit of the wireless power transfer circuit provided by the present invention. Figure 4 , Figure 5 and Figure 6 Together they form a wireless power transfer circuit, and a simulation experiment was conducted with bilateral parameter offset. The result was obtained by monitoring the secondary current. Figure 7 The waveform of the secondary current when the primary and secondary side parameters shift is shown below. Figure 7 It can be seen that even when there is a shift on both sides, the wireless power transmission circuit provided by this invention can still achieve constant current output.

[0103] The anti-parameter offset method provided in this embodiment of the invention is based on the above-mentioned wireless power transmission circuit, which includes the implementation mode and function of the wireless power transmission circuit. For specific implementation methods, please refer to the specific embodiments of the wireless power transmission circuit, which will not be repeated here.

[0104] The wireless power transmission circuit, system, and anti-parameter offset method provided by the present invention have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A wireless power transmission circuit, characterized in that, It includes a DC voltage source, a coupled primary-side circuit and a secondary-side circuit, wherein the primary-side circuit includes an inverter bridge circuit, an automatic tuning auxiliary circuit, a primary-side compensation capacitor and a primary-side inductor; The DC voltage source is connected to the inverter bridge circuit. The positive output terminal of the inverter bridge circuit is connected to the input terminal of the automatic tuning auxiliary circuit. The output terminal of the automatic tuning auxiliary circuit is connected to the first terminal of the primary-side compensation capacitor. The second terminal of the primary-side compensation capacitor is connected to the first terminal of the primary-side inductor. The second terminal of the primary-side inductor is connected to the negative output terminal of the inverter bridge circuit. The inverter bridge circuit and the automatic tuning auxiliary circuit are respectively connected to an external controller. Specifically, the switching frequency of the inverter bridge circuit is adjusted based on the control signal transmitted by the external controller so that the operating frequency of the secondary circuit is the resonant frequency. Then, the voltage compensation of the primary compensation capacitor and the primary inductor is performed by the automatic tuning auxiliary circuit so that the secondary current of the secondary circuit remains constant. The automatic tuning auxiliary circuit includes a fifth switching transistor, a sixth switching transistor, and an adjustment capacitor; The source of the fifth switch and the drain of the sixth switch are connected to the positive output terminal of the inverter bridge circuit. The drain of the fifth switch is connected to the first terminal of the regulating capacitor. The second terminal of the regulating capacitor is connected to the source of the sixth switch and the first terminal of the primary-side compensation capacitor. The gates of the fifth switch and the sixth switch are connected to the external controller.

2. The wireless power transmission circuit according to claim 1, characterized in that, The inverter bridge circuit includes a first switch, a second switch, a third switch, and a fourth switch. The drains of the first and second switching transistors are connected to the positive output terminal of the DC voltage source. The source of the first switching transistor is connected to the drain of the third switching transistor and the input terminal of the automatic tuning auxiliary circuit. The source of the second switching transistor is connected to the drain of the fourth switching transistor and the second terminal of the primary inductor. The sources of the third and fourth switching transistors are connected to the negative output terminal of the DC voltage source. The gates of the first, second, third, and fourth switching transistors are connected to the external controller.

3. The wireless power transmission circuit according to claim 1, characterized in that, The secondary circuit includes a secondary inductor, a secondary compensation capacitor, a rectifier circuit, a filter capacitor, and a load; Wherein, the first end of the secondary inductor is connected to the first end of the secondary compensation capacitor, the second end of the secondary inductor is connected to the positive input terminal of the rectifier circuit, the second end of the secondary compensation capacitor is connected to the negative input terminal of the rectifier circuit, the positive output terminal of the rectifier circuit is connected to the first end of the filter capacitor and the first end of the load, and the negative output terminal of the rectifier circuit is connected to the second end of the filter capacitor and the second end of the load.

4. The wireless power transmission circuit according to claim 3, characterized in that, The rectifier circuit includes a first diode, a second diode, a third diode, and a fourth diode; In this configuration, the anode of the first diode is connected to the second terminal of the secondary compensation capacitor and the cathode of the third diode; the cathode of the first diode is connected to the cathode of the second diode and the first terminal of the filter capacitor; the anode of the second diode is connected to the cathode of the fourth diode and the second terminal of the secondary inductor; and the anodes of the third and fourth diodes are connected to the second terminal of the filter capacitor.

5. A wireless power transmission system, characterized in that, It includes a wireless power transmission circuit, a controller, and a sampling device, wherein the wireless power transmission circuit is the wireless power transmission circuit according to any one of claims 1-4; The sampling device is installed in the wireless power transmission circuit and is used to detect the voltage and current data in the wireless power transmission circuit and transmit it to the controller in real time. The controller is used to control the inverter bridge circuit and the automatic tuning auxiliary circuit in the wireless power transmission circuit according to the voltage and current data, so that the primary circuit and the secondary circuit in the wireless power transmission circuit both operate at the resonant frequency.

6. A method for resisting parameter offsetting, characterized in that, Applicable to the wireless power transmission circuit according to any one of claims 1-4; The anti-parameter offset method includes: Obtain the primary and secondary side parameters of the wireless power transmission circuit; The current secondary resonant frequency is calculated based on the primary and secondary parameters. Adjust the operating frequency of the wireless power transmission circuit to the current secondary resonant frequency; The primary input voltage of the wireless power transfer circuit is adjusted according to the current secondary resonant frequency so that the secondary current of the wireless power transfer circuit remains constant.

7. The anti-parameter shift method according to claim 6, characterized in that, The primary and secondary edge parameters include the first primary and secondary edge parameters and the second primary and secondary edge parameters; Obtaining the primary and secondary side parameters of the wireless power transmission circuit includes: Obtain the first primary and secondary side parameters of the wireless power transmission circuit at the first operating frequency; The operating frequency of the wireless power transmission circuit is switched to the second operating frequency, and the second primary and secondary side parameters are obtained.

8. The anti-parameter offset method according to claim 7, characterized in that, The calculation of the current secondary resonant frequency based on the primary and secondary parameters includes: Substitute the first primary and secondary side parameters and the second primary and secondary side parameters into the preset secondary side LC calculation formula to obtain the first secondary side LC equation and the second secondary side LC equation. Construct a set of secondary side LC equations based on the first secondary side LC equation and the second secondary side LC equation, and solve them to obtain the current secondary side inductance value and the current secondary side compensation capacitor value. The current secondary resonant frequency is calculated based on the current secondary inductance value and the current secondary compensation capacitor value.

9. The anti-parameter shift method according to claim 8, characterized in that, The step of adjusting the primary input voltage of the wireless power transfer circuit according to the current secondary resonant frequency to keep the secondary current of the wireless power transfer circuit constant includes: The inverter drive phase of the inverter bridge circuit in the wireless power transmission circuit is obtained by calculating based on the current secondary resonant frequency. The current voltage drive phase of the automatic tuning auxiliary circuit in the wireless power transmission circuit is calculated based on the inverter drive phase. Based on the current voltage driving phase, the automatic tuning auxiliary circuit adjusts the primary input voltage to keep the secondary current of the wireless power transfer circuit constant.

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