A wireless power transmission power control method and system

Abstract

The present invention discloses a wireless power transmission power control method and system. The method specifically uses a synchronous Buck converter cascaded LCC-S resonant network to form a Buck-LCC-S wireless power transmission system; uses the input voltage U of the LCC-S resonant network to control the power of the wireless power transmission system. in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC‑S resonant network CPP The output power of the Buck-LCC-S wireless power transmission system is calculated. Based on this output power and a preset transmission power, the duty cycle of the synchronous Buck converter is adjusted using PI control to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system. This invention eliminates the need for two-way communication and additional receiving-end control, achieving stable power output under certain coupling coefficients and load variations.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and more particularly to a wireless power transmission power control method and system. Background Art

[0002] In recent years, various types of electronic and electrical equipment have rapidly gained popularity and development, and users have placed new demands on the safety and reliability of power transmission. Traditional plug-in power transmission technology poses safety hazards such as sparks and high-voltage electric shock during charging, reducing system safety, reliability, and service life. It also struggles to meet the safety requirements of some specialized industrial applications. Unlike traditional power transmission methods that rely on direct contact with metal wires, wireless power transmission technology utilizes magnetic fields, lasers, or microwaves as energy transmission media, eliminating the need for direct electrical contact between the power grid and the power-consuming devices. This effectively overcomes the inherent drawbacks and issues of traditional direct contact power supply with metal wires, significantly reducing the use of wires and connection ports in power-consuming devices. Wireless power transmission systems have been the subject of extensive research and study due to their numerous advantages, including safety, electrical isolation, low maintenance, convenience, and the ability to operate in challenging environments and weather conditions. Output power control in wireless power transmission systems has also become a research hotspot. In practical applications such as dynamic wireless power supply, constant-power wireless charging, and adjustable-power power supply, stable output power control is often required. However, in wireless power transmission systems, the output is very sensitive to changes in load and coupling coefficient, and the coupling coefficient and load often change in actual work. If the system output is not controlled, electrical energy cannot be obtained freely and reliably.

[0003] Currently, traditional wireless power transmission systems typically control output power by wirelessly feeding back voltage and current information from the output end to the transmitter circuit for control, or by adding additional DC-DC converters and active rectifier control circuits to the receiver to achieve output control. However, these previous control methods have several drawbacks and shortcomings: Using wireless communication to achieve output power control inevitably affects system stability and reliability due to communication delays, and increases system complexity to a certain extent; adding additional control circuits to the receiver to achieve output power control can affect the transmitter circuit when the load or coupling coefficient changes, requiring additional control at the transmitter and increasing the size of the receiver.

[0004] The prior art discloses a wireless power transmission system and wireless power transmission control method, which includes detecting the supply current using a current sensor; detecting the wireless power transmission status, interruptions, and related information; and determining the power receiving end's demand information; generating electromagnetic waves using an electromagnetic generator; transmitting wireless electromagnetic waves using a transmitting antenna; receiving electromagnetic waves using a receiver; determining whether the transmission is stable and the current load status based on the received wireless power transmission status and interruption information; adjusting the wireless power transmission power using a power regulator based on the judgment result; converting the received electromagnetic waves into electrical energy using an electromagnetic converter; and storing the converted electrical energy using an auxiliary power supply. This solution also suffers from the output being very sensitive to changes in load and coupling coefficient, resulting in unstable output. Summary of the Invention

[0005] The primary purpose of the present invention is to provide a wireless power transmission power control method to achieve stable output power under certain coupling coefficient and load changes.

[0006] A secondary object of the present invention is to provide a wireless power transmission power control system.

[0007] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0008] A method for controlling wireless power transmission power comprises the following steps:

[0009] Use a synchronous Buck converter to cascade an LCC-S resonant network to form a Buck-LCC-S wireless power transmission system;

[0010] Using the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP Calculate the output power of the Buck-LCC-S wireless power transmission system;

[0011] According to the output power and the preset transmission power, the duty cycle of the synchronous Buck converter is adjusted using PI control to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system.

[0012] Preferably, the output power of the Buck-LCC-S wireless power transmission system is calculated as follows:

[0013] Get the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP ;

[0014] The output power P of the Buck-LCC-S wireless power transmission system out for:

[0015]

[0016] Where Z LP The impedance of the inductor at the transmitter end of the LCC-S resonant network is compensated.

[0017] Preferably, the duty cycle of the synchronous Buck converter is adjusted by PI control to control the input voltage of the LCC-S resonant network, specifically:

[0018] Set the preset transmission power Pref;

[0019] The calculated output power P of the Buck-LCC-S wireless power transmission system out The error value is obtained by subtracting the preset transmission power Pref, and the duty cycle is calculated according to the PI algorithm. A PWM wave with the duty cycle is generated and sent to the synchronous Buck converter to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system.

[0020] A wireless power transmission power control system includes a transmitter full-bridge rectifier and filter module, a synchronous Buck converter, a power full-bridge inverter module, a transmitter resonant network, a receiver network, a receiver full-bridge rectifier and filter module, and a control module, wherein:

[0021] The input end of the transmitting end full-bridge rectifier and filter module is connected to the input AC voltage, the output end of the transmitting end full-bridge rectifier and filter module is connected to the input end of the synchronous Buck converter, the output end of the synchronous Buck converter is connected to the input end of the power full-bridge inverter module, the output end of the power full-bridge inverter module is connected to the input end of the transmitting end resonant network, the output end of the transmitting end resonant network is wirelessly connected to the input end of the receiving end network, the output end of the receiving end network is connected to the input end of the receiving end full-bridge rectifier and filter module, the output end of the receiving end full-bridge rectifier and filter module is connected to an external load device, the input end of the control module is respectively connected to the synchronous Buck converter and the transmitting end resonant network, and the output end of the control module is respectively connected to the synchronous Buck converter and the power full-bridge inverter module.

[0022] Preferably, the transmitting end full-bridge rectifier and filter module includes a rectifier diode D1, a rectifier diode D2, a rectifier diode D3, a rectifier diode D4 and a filter capacitor C in ,in:

[0023] The positive electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D3 and one end of the input AC voltage, and the negative electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D2 and the filter capacitor C in The positive electrode of the rectifier diode D3 is connected to the positive electrode of the rectifier diode D4 and the filter capacitor C in The other end of the rectifier diode D4 is connected to the positive electrode of the rectifier diode D2 and the other end of the input AC voltage, and the filter capacitor C in The two ends of the transmitting end full-bridge rectifier and filter module are connected to the synchronous Buck converter as the output ends.

[0024] Preferably, the synchronous Buck converter includes a power switch tube Q1, a power switch tube Q2, a power inductor L1 and an output filter capacitor C0, wherein:

[0025] The input end of the power switch tube Q1 is connected to the filter capacitor C in The output end of the power switch tube Q1 is connected to one end of the power inductor L1 and the input end of the power switch tube Q2 respectively. The other end of the power inductor L1 is connected to one end of the output filter capacitor C0. The output end of the power switch tube Q2 is connected to the filter capacitor C0 respectively. in The other end of the output filter capacitor C0 is connected, and the two ends of the output filter capacitor C0 are connected to the power full-bridge inverter module as the output ends of the synchronous Buck converter;

[0026] The two ends of the output filter capacitor C0 are also connected to the input end of the control module, and the control end of the power switch tube Q1 and the control end of the power switch tube Q2 are connected to the output end of the control module.

[0027] Preferably, the power full-bridge inverter module includes a power switch tube Q3, a power switch tube Q4, a power switch tube Q5 and a power switch tube Q6, wherein:

[0028] The input end of the power switch tube Q3 is respectively connected to one end of the output filter capacitor C0 and the input end of the power switch tube Q5. The output end of the power switch tube Q3 is connected to the input end of the power switch tube Q4. The output end of the power switch tube Q4 is respectively connected to the other end of the output filter capacitor C0 and the output end of the power switch tube Q6. The input end of the power switch tube Q6 is connected to the output end of the power switch tube Q5. The output ends of the power switch tube Q3 and the power switch tube Q5 serve as the output ends of the power full-bridge inverter module and are connected to the transmitting end resonant network.

[0029] The control end of the power switch tube Q3 , the control end of the power switch tube Q4 , the control end of the power switch tube Q5 and the control end of the power switch tube Q6 are all connected to the output end of the control module.

[0030] Preferably, the power switch tubes Q1, Q2, Q3, Q4, Q5 and Q6 are all MOS tubes, wherein the gate of the MOS tube is the control end, the drain of the MOS tube is the input end, and the source is the output end.

[0031] Preferably, the transmitting end resonant network includes a resonant inductor L P , excitation inductance L m , parallel resonant capacitor C P and series resonant capacitor C T ,in:

[0032] The resonant inductor L P One end of the resonant inductor L is connected to the output end of the power switch tube Q3. P The other end is connected to the parallel resonant capacitor C P One end of the excitation inductance L m One end of the excitation inductor L is connected m The other end of the series resonant capacitor C T One end of the series resonant capacitor C T The other end is connected to the parallel resonant capacitor C P The other end of the power switch tube Q5 is connected to the excitation inductor L m A transmitting coil, serving as an output end of the transmitting-end resonant network and wirelessly connected to the receiving-end network;

[0033] The parallel resonant capacitor C P The two ends are also connected to the input end of the control module.

[0034] Preferably, the receiving end network includes a resonant capacitor C1 and an excitation inductor L S ,in:

[0035] The excitation inductance L S is a receiving coil, which is wirelessly connected to the transmitting end resonant network, and the excitation inductor L S One end of the resonant capacitor C1 is connected to one end of the resonant capacitor C1, and the other end of the resonant capacitor C1 is connected to the excitation inductor L S The other end serves as the output end of the receiving end network and is connected to the receiving end full-bridge rectifier and filter module.

[0036] Preferably, the receiving end full-bridge rectifier and filter module includes power diodes D5, D6, D7, D8, and filter capacitors C f ,in:

[0037] The anode of the power diode D5 is connected to the cathode of the power diode D7 and the other end of the resonant capacitor C1, and the cathode of the power diode D5 is connected to the cathode of the power diode D6 and the filter capacitor C f The positive electrode of the power diode D6 is connected to the negative electrode of the power diode D8, and the positive electrode of the power diode D8 is connected to the filter capacitor C f The other end of the power diode D7 is connected to the positive electrode, and the filter capacitor C f The two ends of the receiving end full-bridge rectifier and filter module are connected to the external load device as the output ends.

[0038] Preferably, the control module includes a microcontroller, a first PWM generator, a PI control module, an auxiliary power supply, a parallel capacitor C P Peak voltage sampling module, Buck output voltage sampling module and first optocoupler isolation drive circuit, wherein:

[0039] The auxiliary power supply is respectively connected to the microcontroller, the PI control module, and the parallel capacitor C P The peak voltage sampling module, the Buck output voltage sampling module, the first PWM generator and the first optical coupler isolation drive circuit are connected, and the parallel capacitor C P The input terminal of the peak voltage sampling module is connected to the parallel resonant capacitor C P The two ends of the Buck output voltage sampling module are connected, the input end of the Buck output voltage sampling module is connected to the two ends of the output filter capacitor C0, and the input end of the microcontroller is connected to the parallel capacitor C P The output end of the peak voltage sampling module and the output end of the Buck output voltage sampling module are connected, the output end of the microcontroller is connected to the input end of the PI control module, the output end of the PI control module is connected to the input end of the first PWM generator, the output end of the first PWM generator is connected to the input end of the first optocoupler isolation drive circuit, and the output end of the first optocoupler isolation drive circuit is respectively connected to the control end of the power switch tube Q1 and the control end of the power switch tube Q2 in the synchronous Buck converter.

[0040] Preferably, it further includes a second optocoupler isolation drive circuit and a second PWM generator, wherein:

[0041] The output end of the microcontroller is also connected to the input end of the second PWM generator, the output end of the second PWM generator is connected to the input end of the second optocoupler isolation drive circuit, and the output end of the second optocoupler isolation drive circuit is connected to the control end of the power switch tube Q3, the control end of the power switch tube Q4, the control end of the power switch tube Q5, and the control end of the power switch tube Q6 in the power full-bridge inverter module.

[0042] Compared with the prior art, the beneficial effects of the technical solution of the present invention are:

[0043] The present invention does not require two-end communication and additional receiving end control, and can realize output power control when the coupling coefficient changes, overcoming the problem that the output power control of the traditional wireless power transmission system is mainly focused on the fixed coupling coefficient of the coil. It can realize output power control when the load changes, only requires a high-frequency rectification circuit without the need for an additional control circuit, reduces the size of the receiving end, and has high transmission efficiency. It can realize soft switching and improve the efficiency of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] Figure 1 Schematic diagram of the method of the present invention.

[0045] Figure 2 This is a schematic diagram of the output power control principle of the present invention.

[0046] Figure 3 Schematic diagram of the system module of the present invention.

[0047] Figure 4 Schematic diagram of the system circuit structure of the present invention.

[0048] Figure 5 Schematic diagram of the equivalent model of the wireless power transmission power control system, where (a) is the decoupling circuit equivalent model and (b) is the simplified equivalent circuit.

[0049] Figure 6 Schematic diagram of the control module of the present invention. DETAILED DESCRIPTION

[0050] The accompanying drawings are for illustrative purposes only and are not to be construed as limiting this patent;

[0051] In order to better illustrate this embodiment, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product size;

[0052] It is understandable to those skilled in the art that some well-known structures and descriptions thereof may be omitted in the drawings.

[0053] The technical solution of the present invention is further described below with reference to the accompanying drawings and embodiments.

[0054] Example 1

[0055] This embodiment provides a wireless power transmission power control method. Figure 1 As shown, the following steps are included:

[0056] Use a synchronous Buck converter to cascade an LCC-S resonant network to form a Buck-LCC-S wireless power transmission system;

[0057] Using the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP Calculate the output power of the Buck-LCC-S wireless power transmission system;

[0058] According to the output power and the preset transmission power, the duty cycle of the synchronous Buck converter is adjusted using PI control to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system.

[0059] The output power of the Buck-LCC-S wireless power transmission system is calculated as follows:

[0060] Get the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP ;

[0061] The output power P of the Buck-LCC-S wireless power transmission system out for:

[0062]

[0063] Where Z LP The impedance of the inductor at the transmitter end of the LCC-S resonant network is compensated.

[0064] The PI control is used to adjust the duty cycle of the synchronous Buck converter to control the input voltage of the LCC-S resonant network, specifically:

[0065] Set the preset transmission power Pref;

[0066] The calculated output power P of the Buck-LCC-S wireless power transmission system outThe error value is obtained by subtracting the preset transmission power Pref, and the duty cycle is calculated according to the PI algorithm. A PWM wave with the duty cycle is generated and sent to the synchronous Buck converter to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system.

[0067] The control principle of this embodiment is as follows Figure 2 As shown, this embodiment uses differential sampling to connect the parallel resonant capacitor C at the transmitting end of the LCC-S resonant network. P The upper voltage is scaled down and fed into the peak detection circuit to obtain the resonant capacitor C P The peak voltage Vcpp of the full-bridge power converter is collected at the same time. ab . Use DSP controller to collect Vcpp and V ab The output power Pout is calculated and the difference between it and the set output power Pref is used to get the error value. The error value is then sent to the PI controller to get the control value duty cycle D, which is passed to the PWM generator. The PWM generator adjusts the input voltage V of the full-bridge converter according to the received control value duty cycle D. ab Control is performed to control the output power of the wireless power transmission system.

[0068] Example 2

[0069] This embodiment provides a wireless power transmission power control system. Figure 3 and Figure 4 As shown, it includes a transmitter full-bridge rectifier and filter module, a synchronous Buck converter, a power full-bridge inverter module, a transmitter resonant network, a receiver network and a receiver full-bridge rectifier and filter module, and a control module, wherein:

[0070] The input end of the transmitting end full-bridge rectifier and filter module is connected to the input AC voltage, the output end of the transmitting end full-bridge rectifier and filter module is connected to the input end of the synchronous Buck converter, the output end of the synchronous Buck converter is connected to the input end of the power full-bridge inverter module, the output end of the power full-bridge inverter module is connected to the input end of the transmitting end resonant network, the output end of the transmitting end resonant network is wirelessly connected to the input end of the receiving end network, the output end of the receiving end network is connected to the input end of the receiving end full-bridge rectifier and filter module, the output end of the receiving end full-bridge rectifier and filter module is connected to an external load device, the input end of the control module is respectively connected to the synchronous Buck converter and the transmitting end resonant network, and the output end of the control module is respectively connected to the synchronous Buck converter and the power full-bridge inverter module.

[0071] The transmitter full-bridge rectifier and filter module includes rectifier diodes D1, D2, D3, D4 and filter capacitor C. in ,in:

[0072] The positive electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D3 and one end of the input AC voltage, and the negative electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D2 and the filter capacitor C in The positive electrode of the rectifier diode D3 is connected to the positive electrode of the rectifier diode D4 and the filter capacitor C in The other end of the rectifier diode D4 is connected to the positive electrode of the rectifier diode D2 and the other end of the input AC voltage, and the filter capacitor C in The two ends of the transmitting end full-bridge rectifier and filter module are connected to the synchronous Buck converter as the output ends.

[0073] The synchronous Buck converter includes a power switch tube Q1, a power switch tube Q2, a power inductor L1 and an output filter capacitor C0, wherein:

[0074] The input end of the power switch tube Q1 is connected to the filter capacitor C in The output end of the power switch tube Q1 is connected to one end of the power inductor L1 and the input end of the power switch tube Q2 respectively. The other end of the power inductor L1 is connected to one end of the output filter capacitor C0. The output end of the power switch tube Q2 is connected to the filter capacitor C0 respectively. in The other end of the output filter capacitor C0 is connected, and the two ends of the output filter capacitor C0 are connected to the power full-bridge inverter module as the output ends of the synchronous Buck converter;

[0075] The two ends of the output filter capacitor C0 are also connected to the input end of the control module, and the control end of the power switch tube Q1 and the control end of the power switch tube Q2 are connected to the output end of the control module.

[0076] The power full-bridge inverter module includes a power switch tube Q3, a power switch tube Q4, a power switch tube Q5 and a power switch tube Q6, wherein:

[0077] The input end of the power switch tube Q3 is respectively connected to one end of the output filter capacitor C0 and the input end of the power switch tube Q5. The output end of the power switch tube Q3 is connected to the input end of the power switch tube Q4. The output end of the power switch tube Q4 is respectively connected to the other end of the output filter capacitor C0 and the output end of the power switch tube Q6. The input end of the power switch tube Q6 is connected to the output end of the power switch tube Q5. The output ends of the power switch tube Q3 and the power switch tube Q5 serve as the output ends of the power full-bridge inverter module and are connected to the transmitting end resonant network.

[0078] The control end of the power switch tube Q3 , the control end of the power switch tube Q4 , the control end of the power switch tube Q5 and the control end of the power switch tube Q6 are all connected to the output end of the control module.

[0079] The power switch tubes Q1, Q2, Q3, Q4, Q5 and Q6 are all MOS tubes, wherein the gate of the MOS tube is the control end, the drain of the MOS tube is the input end, and the source is the output end.

[0080] The transmitting end resonant network includes a resonant inductor L P , excitation inductance L m , parallel resonant capacitor C P and series resonant capacitor C T ,in:

[0081] The resonant inductor L P One end of the resonant inductor L is connected to the output end of the power switch tube Q3. P The other end is connected to the parallel resonant capacitor C P One end of the excitation inductance L m One end of the excitation inductor L is connected m The other end of the series resonant capacitor C T One end of the series resonant capacitor C T The other end is connected to the parallel resonant capacitor C P The other end of the power switch tube Q5 is connected to the excitation inductor L m A transmitting coil, serving as an output end of the transmitting-end resonant network and wirelessly connected to the receiving-end network;

[0082] The parallel resonant capacitor C P The two ends are also connected to the input end of the control module.

[0083] The receiving end network includes a resonant capacitor C1 and an excitation inductor L S ,in:

[0084] The excitation inductance L S is a receiving coil, which is wirelessly connected to the transmitting end resonant network, and the excitation inductor L S One end of the resonant capacitor C1 is connected to one end of the resonant capacitor C1, and the other end of the resonant capacitor C1 is connected to the excitation inductor L S The other end serves as the output end of the receiving end network and is connected to the receiving end full-bridge rectifier and filter module.

[0085] The receiving end full-bridge rectifier and filter module includes power diodes D5, D6, D7, D8, and filter capacitor C f ,in:

[0086] The anode of the power diode D5 is connected to the cathode of the power diode D7 and the other end of the resonant capacitor C1, and the cathode of the power diode D5 is connected to the cathode of the power diode D6 and the filter capacitor C f The positive electrode of the power diode D6 is connected to the negative electrode of the power diode D8, and the positive electrode of the power diode D8 is connected to the filter capacitor C f The other end of the power diode D7 is connected to the positive electrode, and the filter capacitor C f The two ends of the receiving end full-bridge rectifier and filter module are connected to the external load device as the output ends.

[0087] The control module is as follows Figure 6 As shown, it includes a microcontroller, a first PWM generator, a PI control module, an auxiliary power supply, a parallel capacitor C P Peak voltage sampling module, Buck output voltage sampling module and first optocoupler isolation drive circuit, wherein:

[0088] The auxiliary power supply is respectively connected to the microcontroller, the PI control module, and the parallel capacitor C P The peak voltage sampling module, the Buck output voltage sampling module, the first PWM generator and the first optical coupler isolation drive circuit are connected, and the parallel capacitor C P The input terminal of the peak voltage sampling module is connected to the parallel resonant capacitor C P The two ends of the Buck output voltage sampling module are connected, the input end of the Buck output voltage sampling module is connected to the two ends of the output filter capacitor C0, and the input end of the microcontroller is connected to the parallel capacitor C PThe output end of the peak voltage sampling module and the output end of the Buck output voltage sampling module are connected, the output end of the microcontroller is connected to the input end of the PI control module, the output end of the PI control module is connected to the input end of the first PWM generator, the output end of the first PWM generator is connected to the input end of the first optocoupler isolation drive circuit, and the output end of the first optocoupler isolation drive circuit is respectively connected to the control end of the power switch tube Q1 and the control end of the power switch tube Q2 in the synchronous Buck converter.

[0089] The microcontroller connects the capacitor C P The peak voltage sampling module and the Buck output voltage sampling module obtain the parallel capacitance C P The peak voltage and the output voltage of the synchronous Buck converter are used to calculate the system output power according to formula (13). The PI control module is used to control the PWM generator to output two PWM waves with a frequency of f2 and a variable duty cycle. The PWM waves are driven by the first optocoupler isolation drive circuit to drive the power switches Q1 and Q2 in the synchronous Buck converter, thereby controlling the output voltage of the synchronous Buck converter and further controlling the system output power.

[0090] It also includes a second optocoupler isolation drive circuit and a second PWM generator, wherein:

[0091] The output end of the microcontroller is also connected to the input end of the second PWM generator, the output end of the second PWM generator is connected to the input end of the second optocoupler isolation drive circuit, and the output end of the second optocoupler isolation drive circuit is connected to the control end of the power switch tube Q3, the control end of the power switch tube Q4, the control end of the power switch tube Q5, and the control end of the power switch tube Q6 in the power full-bridge inverter module.

[0092] In this embodiment, the microcontroller controls the second PWM generator to generate four PWM waves with a frequency of f1 and a duty cycle of 50%, and drives the power switch tubes Q3, Q4, Q5 and Q6 through the second optocoupler isolation drive circuit to realize the half-bridge inverter function at the transmitting end.

[0093] Example 3

[0094] This embodiment describes the working principle of the wireless power transmission power control method based on Embodiments 1 and 2.

[0095] The transmitting end resonant network and the receiving end network in Example 2 together form an LCC-S resonant network. The function of this part of the circuit is to convert the AC square wave into a high-frequency AC sine wave through the resonant network, so that the energy can be transmitted to the receiving end through the resonance mode. Figure 4The circuit structure shown can be simplified to Figure 5 The equivalent circuit model is shown.

[0096] is the fundamental equivalent AC source, and:

[0097]

[0098] in V ab is the output voltage of the synchronous Buck converter, ω is the angular frequency;

[0099] Transmitter reflection impedance R eq for:

[0100]

[0101] Where ω is the angular frequency, R e is the AC load resistance, M is the mutual inductance between the transmitting coil and the receiving coil

[0102] Using Kirchhoff’s voltage law (KVL) and Kirchhoff’s current law (KCL), we can get Figure 5 (b) You can get:

[0103]

[0104] where Z Lm =jωL m ,Z LP =jωL P ,

[0105] When the WPT (wireless power transmission) system is resonant, the energy and efficiency of transmission are the highest. In order for the LCC-S type WPT system to operate in a resonant state, the transmitter needs to meet the following requirements:

[0106]

[0107] Combining formula (3) and formula (4), we can get:

[0108]

[0109] because According to formula (5), we can get:

[0110]

[0111] Depend on Figure 5 (a) It can be seen that when the receiving end resonates, Then the AC equivalent output voltage is derived for:

[0112]

[0113] In formula (5) Bring in available for:

[0114]

[0115] Thus, the output DC power P can be obtained out for:

[0116]

[0117] From formula (6) and formula (9), we can get:

[0118]

[0119] Thus, the voltage of the parallel resonant capacitor CP can be obtained for:

[0120]

[0121] The peak voltage V of the capacitor can be obtained from formula (11): CPP for:

[0122]

[0123] Then we can know the output power P out for:

[0124]

[0125] From formula (13), we can see that the output power of the LCC-S compensation wireless power transmission system can be obtained by the parallel capacitor C P The peak voltage Vcpp and the LCC-S compensation network input voltage U in It is expressed without knowing the mutual inductance and load size of the coil. And the capacitance C P In the system, it not only participates in resonance but also interacts with the inductor L P The low-pass filter effectively reduces the influence of high-order harmonics, so the capacitor C P The voltage information on the output power of the system can more accurately reflect the output power of the system. From formula (9), it can be seen that under the same mutual inductance and load conditions, the output power Pout increases monotonically with the input voltage Uin. Similarly, the output power Pout in the transformed formula (13) also increases monotonically with the input voltage Uin. In order to control the output power, a first-level Buck circuit is added and the PI (proportional and integral regulation) control method is used to adjust the input voltage of the LCC-S compensation network.

[0126] The same or similar reference numerals correspond to the same or similar components;

[0127] The terms used in the drawings to describe positional relationships are for illustrative purposes only and should not be construed as limiting this patent;

[0128] Obviously, the above embodiments of the present invention are merely examples for the purpose of clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the claims of the present invention.

Claims

1. A wireless power transmission power control method, characterized in that: The following steps are involved: Use a synchronous Buck converter to cascade an LCC-S resonant network to form a Buck-LCC-S wireless power transmission system; Using the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP Calculate the output power of the Buck-LCC-S wireless power transmission system; According to the output power and the preset transmission power, the duty cycle of the synchronous Buck converter is adjusted using PI control to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system; The output power of the Buck-LCC-S wireless power transmission system is calculated as follows: Get the input voltage U of the LCC-S resonant network in The peak voltage V of the capacitor connected in parallel with the transmitting coil at the transmitting end of the LCC-S resonant network CPP ; The output power P of the Buck-LCC-S wireless power transmission system out for: Where Z LP The impedance of the inductor at the transmitter end of the LCC-S resonant network is compensated.

2. The wireless power transmission power control method according to claim 1, wherein: The PI control is used to adjust the duty cycle of the synchronous Buck converter to control the input voltage of the LCC-S resonant network, specifically: Set the preset transmission power Pref; The calculated output power P of the Buck-LCC-S wireless power transmission system out The error value is obtained by subtracting the preset transmission power Pref, and the duty cycle is calculated according to the PI algorithm. A PWM wave with the duty cycle is generated and sent to the synchronous Buck converter to control the input voltage of the LCC-S resonant network, thereby controlling the output power of the Buck-LCC-S wireless power transmission system.

3. A wireless power transmission power control system, applied to the wireless power transmission power control method according to claim 1 or 2, characterized in that: It includes a transmitter full-bridge rectifier and filter module, a synchronous Buck converter, a power full-bridge inverter module, a transmitter resonant network, a receiver network, a receiver full-bridge rectifier and filter module, and a control module, among which: The input end of the transmitting end full-bridge rectifier and filter module is connected to the input AC voltage, the output end of the transmitting end full-bridge rectifier and filter module is connected to the input end of the synchronous Buck converter, the output end of the synchronous Buck converter is connected to the input end of the power full-bridge inverter module, the output end of the power full-bridge inverter module is connected to the input end of the transmitting end resonant network, the output end of the transmitting end resonant network is wirelessly connected to the input end of the receiving end network, the output end of the receiving end network is connected to the input end of the receiving end full-bridge rectifier and filter module, the output end of the receiving end full-bridge rectifier and filter module is connected to an external load device, the input end of the control module is respectively connected to the synchronous Buck converter and the transmitting end resonant network, and the output end of the control module is respectively connected to the synchronous Buck converter and the power full-bridge inverter module.

4. The wireless power transmission power control system according to claim 3, characterized in that: The transmitter full-bridge rectifier and filter module includes rectifier diodes D1, D2, D3, D4 and filter capacitor C. in ,in: The positive electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D3 and one end of the input AC voltage, and the negative electrode of the rectifier diode D1 is connected to the negative electrode of the rectifier diode D2 and the filter capacitor C in The positive electrode of the rectifier diode D3 is connected to the positive electrode of the rectifier diode D4 and the filter capacitor C in The other end of the rectifier diode D4 is connected to the positive electrode of the rectifier diode D2 and the other end of the input AC voltage, and the filter capacitor C in The two ends of the transmitting end full-bridge rectifier and filter module are connected to the synchronous Buck converter as the output ends.

5. The wireless power transmission power control system according to claim 4, characterized in that: The synchronous Buck converter includes a power switch tube Q1, a power switch tube Q2, a power inductor L1 and an output filter capacitor C0, wherein: The input end of the power switch tube Q1 is connected to the filter capacitor C in The output end of the power switch tube Q1 is connected to one end of the power inductor L1 and the input end of the power switch tube Q2 respectively. The other end of the power inductor L1 is connected to one end of the output filter capacitor C0. The output end of the power switch tube Q2 is connected to the filter capacitor C0 respectively. in The other end of the output filter capacitor C0 is connected, and the two ends of the output filter capacitor C0 are connected to the power full-bridge inverter module as the output ends of the synchronous Buck converter; The two ends of the output filter capacitor C0 are also connected to the input end of the control module, and the control end of the power switch tube Q1 and the control end of the power switch tube Q2 are connected to the output end of the control module.

6. The wireless power transmission power control system according to claim 5, characterized in that: The power full-bridge inverter module includes a power switch tube Q3, a power switch tube Q4, a power switch tube Q5 and a power switch tube Q6, wherein: The input end of the power switch tube Q3 is respectively connected to one end of the output filter capacitor C0 and the input end of the power switch tube Q5. The output end of the power switch tube Q3 is connected to the input end of the power switch tube Q4. The output end of the power switch tube Q4 is respectively connected to the other end of the output filter capacitor C0 and the output end of the power switch tube Q6. The input end of the power switch tube Q6 is connected to the output end of the power switch tube Q5. The output ends of the power switch tube Q3 and the power switch tube Q5 serve as the output ends of the power full-bridge inverter module and are connected to the transmitting end resonant network. The control end of the power switch tube Q3 , the control end of the power switch tube Q4 , the control end of the power switch tube Q5 and the control end of the power switch tube Q6 are all connected to the output end of the control module.

7. The wireless power transmission power control system according to claim 6, characterized in that: The transmitting end resonant network includes a resonant inductor L P , excitation inductance L m , parallel resonant capacitor C P and series resonant capacitor C T The receiving end network includes a resonant capacitor C1 and an excitation inductor L S ,in: The resonant inductor L P One end of the resonant inductor L is connected to the output end of the power switch tube Q3. P The other end is connected to the parallel resonant capacitor C P One end of the excitation inductance L m One end of the excitation inductor L is connected m The other end of the series resonant capacitor C T One end of the series resonant capacitor C T The other end is connected to the parallel resonant capacitor C P The other end of the power switch tube Q5 is connected to the excitation inductor L m A transmitting coil, serving as an output end of the transmitting-end resonant network and wirelessly connected to the receiving-end network; The parallel resonant capacitor C P The two ends are also connected to the input end of the control module; The excitation inductance L S is a receiving coil, which is wirelessly connected to the transmitting end resonant network, and the excitation inductor L S One end of the resonant capacitor C1 is connected to one end of the resonant capacitor C1, and the other end of the resonant capacitor C1 is connected to the excitation inductor L S The other end serves as the output end of the receiving end network and is connected to the receiving end full-bridge rectifier and filter module.

8. The wireless power transmission power control system according to claim 7, characterized in that: The receiving end full-bridge rectifier and filter module includes power diodes D5, D6, D7, D8, and filter capacitor C f ,in: The anode of the power diode D5 is connected to the cathode of the power diode D7 and the other end of the resonant capacitor C1, and the cathode of the power diode D5 is connected to the cathode of the power diode D6 and the filter capacitor C f The positive electrode of the power diode D6 is connected to the negative electrode of the power diode D8, and the positive electrode of the power diode D8 is connected to the filter capacitor C f The other end of the power diode D7 is connected to the positive electrode, and the filter capacitor C f The two ends of the receiving end full-bridge rectifier and filter module are connected to the external load device as the output ends.

9. The wireless power transmission power control system according to claim 8, characterized in that: The control module includes a microcontroller, a first PWM generator, a PI control module, an auxiliary power supply, a parallel capacitor C P Peak voltage sampling module, Buck output voltage sampling module, first optocoupler isolation drive circuit, second optocoupler isolation drive circuit and second PWM generator, wherein: The auxiliary power supply is respectively connected to the microcontroller, the PI control module, and the parallel capacitor C P The peak voltage sampling module, the Buck output voltage sampling module, the first PWM generator and the first optical coupler isolation drive circuit are connected, and the parallel capacitor C P The input terminal of the peak voltage sampling module is connected to the parallel resonant capacitor C P The two ends of the Buck output voltage sampling module are connected, the input end of the Buck output voltage sampling module is connected to the two ends of the output filter capacitor C0, and the input end of the microcontroller is connected to the parallel capacitor C P The output end of the peak voltage sampling module and the output end of the Buck output voltage sampling module are connected, the output end of the microcontroller is connected to the input end of the PI control module, the output end of the PI control module is connected to the input end of the first PWM generator, the output end of the first PWM generator is connected to the input end of the first optocoupler isolation drive circuit, and the output end of the first optocoupler isolation drive circuit is respectively connected to the control end of the power switch tube Q1 and the control end of the power switch tube Q2 in the synchronous Buck converter; The output end of the microcontroller is also connected to the input end of the second PWM generator, the output end of the second PWM generator is connected to the input end of the second optocoupler isolation drive circuit, and the output end of the second optocoupler isolation drive circuit is connected to the control end of the power switch tube Q3, the control end of the power switch tube Q4, the control end of the power switch tube Q5, and the control end of the power switch tube Q6 in the power full-bridge inverter module.

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