Constant frequency time-reversal symmetry wireless power transmission constant voltage constant current constant power control method

Abstract

The application provides a kind of fixed frequency parity time symmetry radio energy transmission constant voltage constant current constant power control method, belongs to wireless power transmission technical field, the method includes: when the capacitance value of adjustable capacitor is adjusted to first capacitance value, the first phase difference between the output voltage of inverter and the current of transmitting end is obtained, and when the capacitance value of adjustable capacitor is adjusted to second capacitance value, the second phase difference between the output voltage of inverter and the current of transmitting end is obtained;The mutual inductance value between transmitting coil and receiving coil is obtained;Based on the resistance value of load and mutual inductance value, the transmitting end adjustment coefficient is obtained, the target capacitance value of adjustable capacitor is determined, and the capacitance value of adjustable capacitor is adjusted to target capacitance value;Based on transmitting end adjustment coefficient, resistance value of load, target working mode of wireless power transmission system and target output value, the duty cycle of voltage converter is controlled.The method provided by the application can meet the reliability requirements of power supply system in mine environment.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically relating to a constant voltage, constant current and constant power control method for fixed frequency parity-time symmetric wireless power transmission. Background Technology

[0002] Coal mines pose significant risks of flammable and explosive substances such as methane and coal dust. Traditional wired power supply is insufficient to meet inherent safety requirements due to issues like sparks from plugging and unplugging, and cable wear and leakage. Wireless power transfer technology, through contactless power supply, can eliminate electrical sparks at the source, effectively reducing the risk of methane ignition and solving the problem of frequent charging of mobile devices. However, existing wireless power transfer technologies face numerous challenges in actual coal mine conditions: the load and coupling coefficient are often perturbed simultaneously, while existing control strategies mostly target single-parameter disturbances, limiting their applicability; feedback control relying on communication requires additional communication modules, increasing cost and complexity, and reliability and real-time performance are difficult to guarantee under strong electromagnetic interference underground; complex topology switching circuits designed to achieve multi-objective constant output suffer from problems such as non-purely resistive input impedance, large size, cumbersome control, and switching shocks, affecting system stability; existing parameter identification methods are complex and computationally intensive, and some still rely on topology switching, failing to simplify the system structure. Summary of the Invention

[0003] In view of the above problems, this application provides a constant-voltage, constant-current, and constant-power control method for fixed-frequency, parity-time symmetric wireless power transfer, so as to overcome the above problems or at least partially solve the above problems.

[0004] In a first aspect, this application provides a constant-voltage, constant-current, and constant-power control method for fixed-frequency, parity-time symmetric wireless power transfer, applied to a wireless power transfer system. The wireless power transfer system includes a transmitter and a receiver. The transmitter includes a transmitting coil, an adjustable capacitor, an inverter, and a voltage converter. The adjustable capacitor is connected in series with the transmitting coil. The receiver includes a receiving coil and a load. The method includes: when the capacitance value of the adjustable capacitor is adjusted to a first capacitance value, obtaining a first phase difference between the output voltage of the inverter and the current of the transmitter; and when the capacitance value of the adjustable capacitor is adjusted to a second capacitance value, obtaining a second phase difference between the output voltage of the inverter and the current of the transmitter; wherein the first capacitance value and the second capacitance value are different; based on the first phase difference and the second phase difference... The system uses a preset load calculation model to obtain the resistance value of the load, and a preset mutual inductance calculation model to obtain the mutual inductance value between the transmitting coil and the receiving coil. Based on the resistance value of the load and the mutual inductance value, the system obtains the transmitting end adjustment coefficient, and based on the transmitting end adjustment coefficient, determines the target capacitance value of the adjustable capacitor, and adjusts the capacitance value of the adjustable capacitor to the target capacitance value so that the wireless power transmission system is in a parity-time symmetric state. Based on the transmitting end adjustment coefficient, the resistance value of the load, the target operating mode of the wireless power transmission system, and the target output value of the target operating mode, the system controls the duty cycle of the voltage converter. The target operating mode is one of constant current mode, constant voltage mode, and constant power mode.

[0005] In some embodiments, controlling the duty cycle of the voltage converter based on the transmitter regulation coefficient, the resistance value of the load, the target operating mode of the wireless power transmission system, and the target output value of the target operating mode includes: determining a target duty cycle calculation model from a set of preset candidate duty cycle calculation models based on the target operating mode, wherein different candidate duty cycle calculation models correspond to different operating modes; obtaining the target duty cycle corresponding to the target operating mode based on the transmitter regulation coefficient, the resistance value of the load, the target output value, and the target duty cycle calculation model; and controlling the duty cycle of the voltage converter to be the target duty cycle.

[0006] In some embodiments, the multiple candidate duty cycle calculation models include a constant current duty cycle calculation model, a constant voltage duty cycle calculation model, and a constant power duty cycle calculation model; when the target operating mode is the constant current mode, the target duty cycle calculation model is the constant current duty cycle calculation model; when the target operating mode is the constant voltage mode, the target duty cycle calculation model is the constant voltage duty cycle calculation model; when the target operating mode is the constant power mode, the target duty cycle calculation model is the constant power duty cycle calculation model.

[0007] In some embodiments, the target duty cycle corresponding to the target operating mode is obtained based on the transmitter adjustment coefficient, the load resistance value, the target output value, and the target duty cycle calculation model. This includes: inputting the transmitter adjustment coefficient, the load resistance value, the target output value, the input voltage of the wireless power transmission system, the parasitic internal resistance of the transmitter, the parasitic internal resistance of the receiver, the receiver reference coefficient, and the ratio of the transmitting coil to the receiving coil into the target duty cycle calculation model to obtain the target duty cycle corresponding to the target operating mode.

[0008] In some embodiments, the resistance value of the load is obtained based on the first phase difference, the second phase difference, and a preset load calculation model, including: inputting the first phase difference, the second phase difference, the parasitic internal resistance of the receiver, the parasitic resistance of the transmitter, the first reactance, the second reactance, and the reactance of the receiver into the preset load calculation model to obtain the resistance value of the load; wherein, the first reactance is the reactance of the transmitter when the adjustable capacitor is the first capacitance value, and the second reactance is the reactance of the transmitter when the adjustable capacitor is the second capacitance value.

[0009] In some embodiments, the preset load calculation model is: in, This represents the resistance value of the load. This is the first phase difference; This is the second phase difference; This refers to the parasitic internal resistance of the receiving end; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; This is the reactance at the receiving end.

[0010] In some embodiments, obtaining the mutual inductance value between the transmitting coil and the receiving coil based on the first phase difference, the second phase difference, and a preset mutual inductance calculation model includes: inputting the first phase difference, the second phase difference, the parasitic resistance of the transmitting end, the first reactance, the second reactance, the reactance of the receiving end, and the frequency of the wireless power transmission system into the preset mutual inductance calculation model to obtain the mutual inductance value; wherein, the first reactance is the reactance of the transmitting end when the adjustable capacitor is the first capacitance value, and the second reactance is the reactance of the transmitting end when the adjustable capacitor is the second capacitance value.

[0011] In some embodiments, the preset mutual inductance calculation model is: in, Mutual inductance value; This is the first phase difference; This is the second phase difference; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; The reactance at the receiving end; The frequency of a wireless power transmission system.

[0012] In some embodiments, a transmitter adjustment coefficient is obtained based on the resistance value of the load and the mutual inductance value, and a target capacitance value of the adjustable capacitor is determined based on the transmitter adjustment coefficient, including: The resistance value of the load, the mutual inductance value, the receiver reference coefficient, the inductance of the transmitting coil, the inductance of the receiving coil, the reactance of the receiver, the parasitic internal resistance of the receiver, and the frequency of the wireless power transmission system are input into a preset parity-symmetric calculation model to obtain the transmitter adjustment coefficient; based on the transmitter adjustment coefficient, the frequency of the wireless power transmission system, and the inductance of the transmitting coil, the target capacitance value is obtained.

[0013] In some embodiments, the preset symmetric computation model is: in, This is the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The reactance at the receiving end; The frequency for wireless power transmission systems; For the inductance of the transmitting coil, The inductance of the receiving coil; This represents the resistance value of the load. This represents the parasitic internal resistance of the receiving end.

[0014] This embodiment provides a constant-voltage, constant-current, and constant-power control method for fixed-frequency, parity-time symmetric wireless power transfer, applied to a wireless power transfer system. The method includes: when the capacitance value of an adjustable capacitor is adjusted to a first capacitance value, obtaining a first phase difference between the inverter's output voltage and the transmitter's current; and when the capacitance value of the adjustable capacitor is adjusted to a second capacitance value, obtaining a second phase difference between the inverter's output voltage and the transmitter's current. The first and second capacitance values ​​are different. Based on the first and second phase differences and a preset load calculation model, the resistance value of the load is obtained. Furthermore, based on the first and second phase differences and a preset mutual inductance calculation model, the mutual inductance value between the transmitting and receiving coils is obtained. By detecting the voltage and current information at the transmitter, the mutual inductance value and the load resistance can be obtained. Then, based on the load resistance and mutual inductance, the transmitter regulation coefficient is obtained. Based on this coefficient, the target capacitance value of the adjustable capacitor is determined, and the capacitor value is adjusted to match this target value. This ensures the wireless power transmission system operates in a parity-time symmetrical state, fully considering the constant voltage, constant current, and constant power output requirements under both load and mutual inductance disturbances, thus better aligning with the actual operating scenarios of complex conditions such as underground coal mines. Next, based on the transmitter regulation coefficient, load resistance, the target operating mode of the wireless power transmission system, and the target output value of that mode, the duty cycle of the voltage converter is controlled. The target operating mode can be one of constant current, constant voltage, or constant power modes. By simply adjusting the adjustable capacitor value and controlling the voltage converter's duty cycle, constant voltage, constant current, and constant power output can be achieved under both load and mutual inductance disturbances, meeting the high reliability, high safety, and high integration requirements of the power supply system in mining environments. Attached Figure Description

[0015] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0016] Figure 1 This is a schematic diagram of a wireless power transmission system provided in an embodiment of this application; Figure 2 This is a flowchart illustrating the steps of a fixed-frequency parity-time symmetric wireless power transfer constant voltage, constant current, and constant power control method provided in this application embodiment; Figure 3 This is a schematic diagram showing a comparison between theoretical and simulated values ​​of mutual inductance and load, provided in an embodiment of this application. Figure 4This is a schematic diagram illustrating a comparison of mutual inductance and load error provided in an embodiment of this application; Figure 5 This is a waveform diagram of current, voltage, and power in constant current mode provided in the embodiments of this application; Figure 6 This is a waveform diagram of current, voltage, and power under constant voltage mode provided in the embodiments of this application; Figure 7 This is a waveform diagram of current, voltage, and power under constant power mode provided in the embodiments of this application; Figure 8 This is a flowchart of the steps of the wireless power transmission constant voltage, constant current and constant power control method provided in the embodiments of this application; Figure label: 1-Transmitter; 2-Receiver; 3-Voltage converter; 4-Inverter; L1-Transmitting coil; L2-Receiver coil. Detailed Implementation

[0017] Exemplary embodiments of this application will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of this application are shown in the drawings, it should be understood that this application may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided to enable a more thorough understanding of this application and to fully convey the scope of this application to those skilled in the art.

[0018] Figure 1 This is a schematic diagram of a wireless power transmission system provided in an embodiment of this application, as shown below. Figure 1 As shown, A wireless power transfer system includes a transmitter and a receiver. The transmitter includes a transmitting coil, an adjustable capacitor, an inverter, and a voltage converter. The adjustable capacitor is connected in series with the transmitting coil. The receiver includes a receiving coil and a load. The voltage converter can regulate the DC voltage input to the transmitter to a new, controllable DC bus voltage. Specifically, this can be achieved by adjusting... Figure 1 The PWM duty cycle of the switching transistor St allows the voltage converter to output DC voltage higher or lower than the input voltage for use by the inverter. The inverter consists of four power switches: S1, S2, S3, and S4. An adjustable capacitor is connected in series between the first terminal of the transmitting coil and the connection point between the first and second power switches S1 and S2. The parasitic internal resistance of the transmitting end is connected in series between the second terminal of the transmitting coil and the connection point between the third and fourth power switches S3 and S4. The receiving end includes a receiving coil and a load, with the receiving coil coupled to the transmitting coil. D r1、 D r2、 Dr3、 D r4 These are diodes on the receiving end. C r For the filter capacitor at the receiving end, R L This is the equivalent resistance of the receiving end. D 1、 D 2、 D 3、 D 4 are the parasitic diodes of the first power switch S1, the second power switch S2, the third power switch S3, and the fourth power switch S4, respectively. V D 1 is a freewheeling diode, L is a filter inductor, C 1 is the filter capacitor at the transmitting end. For the load current, For the current of the receiving coil, This represents the current in the transmitting coil.

[0019] according to Figure 1 You can get Figure 1 The corresponding KVL (Kirchhoff's Voltage Law) equation (1): (1) The input impedance Z can be obtained from formula (1). in (2) in, Input impedance; This is the inverter output voltage vector; Lp is the parasitic internal resistance of the transmitting end; Lp is the inductance of the transmitting coil. This is the mutual inductance value between the transmitting coil and the receiving coil; This is the current phasor of the transmitting coil; For the current phasor of the receiving coil; It is an adjustable capacitor; The resistance of the load; Parasitic capacitance at the receiving end; This is the compensation capacitor at the receiving end; This is the inductance of the receiving coil.

[0020] Assume the wireless power transmission system satisfies formula (3). (3) in, This is the resonant frequency of the transmitting end; Lp is the resonant frequency of the receiving end; Lp is the inductance of the transmitting coil. The inductance of the receiving coil; It is an adjustable capacitor; This is the compensation capacitor at the receiving end.

[0021] When the imaginary part of the input impedance Zin is 0, the condition that must be met is Equation (4): (4) in, This is the resonant frequency of the transmitting end; This is the resonant frequency of the receiving end; Lp is the parasitic internal resistance of the transmitting end; Lp is the inductance of the transmitting coil. This is the mutual inductance value between the transmitting coil and the receiving coil; It is an adjustable capacitor; The resistance of the load; Parasitic capacitance at the receiving end; This is the compensation capacitor at the receiving end; The inductance of the receiving coil; The reactance at the transmitting end; The reactance at the receiving end; This is the adjustment coefficient at the transmitting end; This is the reference coefficient for the receiving end.

[0022] Let Lp / Ls = α, then the transmission power P and transmission efficiency of the wireless power transmission system at this time are... See formulas (5) and (6): (5) (6) in, This is the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The resistance of the load; Parasitic capacitance at the receiving end; This refers to the parasitic internal resistance at the transmitting end.

[0023] Current on the load , Valid expressions are as follows: (7) (8) in, The current is the load current. The voltage of the load; This is the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The resistance of the load; Parasitic capacitance at the receiving end; The parasitic internal resistance of the transmitting end; This is the voltage output by the inverter; This represents the current in the receiving coil.

[0024] Figure 2 This is a flowchart illustrating the steps of a fixed-frequency, parity-time symmetric wireless power transfer constant-voltage, constant-current, and constant-power control method provided in this application embodiment, applicable to... Figure 1 Wireless power transmission systems, such as Figure 2 As shown, The steps of the fixed-frequency parity-time symmetric wireless power transfer constant voltage, constant current, and constant power control method in this embodiment include: Step S101: When the capacitance value of the adjustable capacitor is adjusted to the first capacitance value, the first phase difference between the output voltage of the inverter and the current at the transmitter is obtained; and when the capacitance value of the adjustable capacitor is adjusted to the second capacitance value, the second phase difference between the output voltage of the inverter and the current at the transmitter is obtained; wherein the first capacitance value and the second capacitance value are different.

[0025] In this embodiment, the current at the transmitting end is the current flowing through the transmitting coil, via... Figure 1 As can be seen from formulas (1) to (8), under the fixed-frequency PT working mechanism, the output power, transmission efficiency, load current, and load voltage are all independent of the mutual inductance. When the system structural parameters, system input voltage, and system compensation δ2 are determined, they are only related to δ1 and the load. Therefore, when the load and mutual inductance change, δ1 can be adjusted in real time to enable the fixed-frequency PT to work.

[0026] By changing the capacitance value of the adjustable capacitor twice, the corresponding phase difference information can be obtained separately, providing a data basis for subsequent system parameter identification. Specifically, the adjustable capacitor is first set to the first capacitance value, C. p =C p0 Detect and record the inverter's output voltage U in the current state. in With the transmitting coil current I p The first phase difference θ between in1 Then the adjustable capacitor was switched to the second capacitance value. C p =0.95 C p0， Obtain the second phase difference θ between the inverter output voltage and the transmitter current. in2 Both phase difference measurements were performed at the same system operating frequency. Based on the input impedance characteristics, the expressions for the two system input phase angles are obtained using formula (9): (9) in, The first reactance; This is the second reactance; θin1 is the reactance of the receiving end; θin2 is the first phase difference; θin1 is the first phase difference. Parasitic capacitance at the receiving end; The resistance of the load; The parasitic internal resistance of the transmitting end; The frequency of the wireless power transmission system is Xp1 = ωLp-1 / (ωCp0), Xp2 = ωLp-1 / (0.95ωCp0), RL = 8RB / π2, Xs = ωLs-1 / (ωCs); Cp0 is an adjustable capacitor.

[0027] Step S102: Based on the first phase difference, the second phase difference, and the preset load calculation model, obtain the resistance value of the load, and based on the first phase difference, the second phase difference, and the preset mutual inductance calculation model, obtain the mutual inductance value between the transmitting coil and the receiving coil.

[0028] In this embodiment, based on the first phase difference, the second phase difference, and a preset load calculation model, specifically: the first phase difference, the second phase difference, the parasitic internal resistance of the receiver, the parasitic resistance of the transmitter, the first reactance, the second reactance, and the reactance of the receiver are input into the preset load calculation model to obtain the resistance value of the load; wherein, the first reactance is the reactance of the transmitter when the adjustable capacitor is at the first capacitance value, and the second reactance is the reactance of the transmitter when the adjustable capacitor is at the second capacitance value.

[0029] In this embodiment, the preset load calculation model is formula (10): (10) in, This represents the resistance value of the load. This is the first phase difference; This is the second phase difference; This refers to the parasitic internal resistance of the receiving end; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; This is the reactance at the receiving end.

[0030] Based on the first phase difference, the second phase difference, and a preset mutual inductance calculation model, the mutual inductance value between the transmitting coil and the receiving coil is obtained. Specifically, the first phase difference, the second phase difference, the parasitic resistance of the transmitting end, the first reactance, the second reactance, the reactance of the receiving end, and the frequency of the wireless power transmission system are input into the preset mutual inductance calculation model to obtain the mutual inductance value. Among them, the first reactance is the reactance of the transmitting end when the adjustable capacitor is at the first capacitance value, and the second reactance is the reactance of the transmitting end when the adjustable capacitor is at the second capacitance value.

[0031] In this embodiment, the preset mutual inductance calculation model is formula (11): (11) in, Mutual inductance value; This is the first phase difference; This is the second phase difference; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; The reactance at the receiving end; The frequency of a wireless power transmission system.

[0032] Step S103: Based on the load resistance and mutual inductance, obtain the transmitter adjustment coefficient, and based on the transmitter adjustment coefficient, determine the target capacitance value of the adjustable capacitor, and adjust the capacitance value of the adjustable capacitor to the target capacitance value so that the wireless power transmission system is in a parity-time symmetric state.

[0033] In this embodiment, to ensure that the wireless power transmission system is in a parity-time symmetric state, the resistance and mutual inductance values ​​of the load obtained by solving equations (10) and (11) can be used to obtain the transmitter adjustment coefficient based on the load's resistance and mutual inductance values, specifically: By inputting the load resistance, mutual inductance, receiver reference coefficient, transmitter coil inductance, receiver coil inductance, receiver reactance, receiver parasitic internal resistance, and the frequency of the wireless power transmission system into a preset parity-symmetric calculation model, the transmitter adjustment coefficient is obtained.

[0034] In this embodiment, the preset symmetric calculation model is formula (12): (12) in, This refers to the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The reactance at the receiving end; The frequency for wireless power transmission systems; For the inductance of the transmitting coil, The inductance of the receiving coil; The resistance value of the load; This represents the parasitic internal resistance of the receiving end.

[0035] Then, based on the transmitter regulation coefficient, the frequency of the wireless power transmission system, and the inductance of the transmitting coil, the target capacitance value is obtained. Specifically, it can be the reciprocal of the product of the square of the wireless power transmission system frequency and the difference between the inductance of the transmitting coil and the transmitter regulation coefficient. See formula (13) for details: (13) in, The target capacitance value; The frequency for wireless power transmission systems; This refers to the adjustment coefficient at the transmitting end; The inductance of the transmitting coil.

[0036] Finally, adjust the capacitance value of the adjustable capacitor to the target capacitance value.

[0037] Step S104: Based on the transmitter regulation coefficient, the load resistance value, the target operating mode of the wireless power transmission system, and the target output value of the target operating mode, control the duty cycle of the voltage converter; wherein, the target operating mode is one of constant current mode, constant voltage mode, and constant power mode.

[0038] In this embodiment, the target operating mode is the mode required for the current wireless power transmission system to operate. The target output value is the desired current, voltage, or power value at the receiver output after controlling the voltage converter, corresponding to constant current mode, constant voltage mode, and constant power mode, respectively. The duty cycle of the voltage converter is controlled as follows: based on the target operating mode, a target duty cycle calculation model is determined from a set of preset candidate duty cycle calculation models. Different candidate duty cycle calculation models correspond to different operating modes. The multiple candidate duty cycle calculation models include a constant current duty cycle calculation model, a constant voltage duty cycle calculation model, and a constant power duty cycle calculation model. The specific method for obtaining the candidate duty cycle calculation models is as follows: First, substitute the preset constant current reference value, constant voltage reference value, and constant power reference value into formula (14) respectively. The inverter output voltage corresponding to constant current mode, constant voltage mode, and constant power mode can be obtained by calculation, i.e., U incc (Constant current mode output voltage), U incv (Constant voltage mode output voltage), U incp (Constant power mode output voltage).

[0039] (14) in, Output voltage in constant current mode; Output voltage in constant voltage mode; This is the output voltage in constant power mode; This is a constant current reference value; This is a constant voltage reference value; This is a constant power reference value; This refers to the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The resistance value of the load; This refers to the parasitic internal resistance of the receiving end; The parasitic internal resistance of the transmitting end; This is the ratio of the transmitting coil to the receiving coil.

[0040] In this embodiment, the multiple candidate duty cycle models are represented by formula (14). By adjusting the duty cycle D of the Buck-Boost (Buck-Boost Converter) converter, the system can stably operate in three modes: constant current mode, constant voltage mode, and constant power mode. The duty cycles required to achieve these three modes are defined as D, respectively. cc (Duty cycle in constant current mode), D cv (Duty cycle in constant voltage mode), D cp (Duty cycle in constant power mode), see formula (15) for details.

[0041] (15) in, This refers to the duty cycle in constant current mode. This refers to the duty cycle in constant voltage mode. This refers to the duty cycle in constant power mode. This is a constant current reference value; This is a constant voltage reference value; This is a constant power reference value; This refers to the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The resistance value of the load; This refers to the parasitic internal resistance of the receiving end; The parasitic internal resistance of the transmitting end; This is the ratio of the transmitting coil to the receiving coil; This is the input voltage of the wireless power transmission system.

[0042] When the target operating mode is constant current mode, the target duty cycle calculation model is the constant current duty cycle calculation model, as shown in the first expression of formula (15).

[0043] When the target operating mode is constant voltage mode, the target duty cycle calculation model is the constant voltage duty cycle calculation model, as shown in the second expression in formula (15).

[0044] When the target operating mode is constant power mode, the target duty cycle calculation model is the constant power duty cycle calculation model, as shown in the third expression in formula (15).

[0045] Finally, based on the transmitter regulation coefficient, load resistance, target output value, and target duty cycle calculation model, the target duty cycle corresponding to the target operating mode is obtained. The duty cycle of the control voltage converter is the target duty cycle. Specifically, the transmitter regulation coefficient, load resistance, target output value, input voltage of the wireless power transmission system, parasitic internal resistance of the transmitter, parasitic internal resistance of the receiver, receiver reference coefficient, and the ratio of the transmitter coil to the receiver coil are input into the target duty cycle calculation model to obtain the target duty cycle corresponding to the target operating mode. Then, the voltage converter is adjusted... Figure 1 If the PWM duty cycle of the switching transistor St is the target duty cycle, the load can output in the expected constant current mode, constant voltage mode, and constant power mode.

[0046] The following will use the simulation data provided in Table 1 to verify the constant voltage, constant current, and constant power control method for fixed-frequency parity-time symmetric wireless power transfer provided in this embodiment. First, a numerical simulation platform using MATLAB will be built. Figure 1 The circuit model of the wireless power transfer system is shown in Table 1. The circuit parameters for the simulation are shown in Table 1.

[0047] Table 1 - Simulation Data Table Based on the data provided in Table 1, 10 sets of parameters were set to verify the feasibility and correctness of mutual inductance identification. 10 sets of mutual inductance and load were set. Table 2 is the theoretical mutual inductance and load setting table, as shown in Table 2.

[0048] Table 2 - Theoretical Mutual Inductance and Load Settings Substituting the set mutual inductance and load parameters into the Simulink simulation, the simulated mutual inductance is shown in Table 3.

[0049] Table 3 - Mutual inductance and load identified by simulation Figure 3 This is a schematic diagram illustrating the comparison between theoretical and simulated values ​​of mutual inductance and load, as provided in an embodiment of this application. Figure 3 As shown, Figure 3 (a) is a waveform diagram comparing the theoretical and simulated values ​​of mutual inductance. The differences between the two values ​​are almost identical. Figure 3 (b) is a waveform diagram comparing the theoretical and simulated load values. Figure 3It can be seen that the waveforms of the theoretical and simulated mutual inductance values ​​are basically consistent, and the waveforms of the theoretical and simulated load values ​​are also basically consistent. The method proposed in this application can effectively overcome the coupling interference of coil offset (mutual inductance change) and load fluctuation on system parameter identification, providing a reliable data basis for subsequent constant current, constant voltage or constant power control based on real-time parameters, thereby ensuring that the wireless power transmission system can still maintain stable and efficient power output under complex working conditions such as underground coal mines.

[0050] Figure 4 This is a schematic diagram illustrating a comparison of mutual inductance and load error provided in an embodiment of this application, as shown below. Figure 4 As shown in (a), the mutual inductance identification errors were 0.07%, 0.57%, 0%, 0.20%, 0.34%, 0.36%, 0.42%, 0.46%, 0.50%, and 0.67%, respectively, with an average error of 0.36%. Figure 4 As shown in (b), the load identification errors are 0.60%, 0.17%, 0%, 0.25%, 0.56%, 0.80%, 1.09%, 1.25%, 1.54% and 2.13%, respectively, with an average error of 0.84%. Figure 4 The simulation results are basically consistent with the theoretical values, verifying the high accuracy of the proposed scheme in mutual inductance and load identification.

[0051] The following will be a constant voltage, constant current, and constant power simulation verification: Constant current mode: During the period of 0.01s-0.05s, the mutual inductance of the wireless power transfer system is set to 88μH and the load is 14Ω. Figure 5 This is a schematic diagram of the waveforms of current, voltage, and power in constant current mode provided in the embodiments of this application, as shown below. Figure 5 As shown in (a), 5(b), and 5(c), in constant current mode, the output current can be stably maintained at 2A regardless of whether there is mutual inductance disturbance or load disturbance in the system, thus achieving constant current control.

[0052] Constant voltage mode: During the period of 0.05s-0.08s, the mutual inductance of the wireless power transmission system is set to 88μH and the load is 12Ω. Figure 6 This is a schematic diagram of the current, voltage, and power waveforms under constant voltage mode provided in the embodiments of this application, as shown below. Figure 6 As shown in (a), 6(b), and 6(c), in constant voltage mode, the output voltage can be stably maintained at 36V in the face of mutual inductance and load disturbances, achieving the effect of constant voltage control.

[0053] Constant power mode: During the period of 0.08s-0.1s, the mutual inductance of the system is set to 79μH and the load is 12Ω. Figure 7 This is a schematic diagram of the current, voltage, and power waveforms in constant power mode provided in an embodiment of this application, as shown below. Figure 7As shown in (a), 7(b), and 7(c), in constant power mode, even with mutual inductance and load disturbances, the output power remains stable at 100W, achieving constant power control. In summary, this verifies the stability and reliability of the solution provided in this application.

[0054] For example, Figure 8 This is a flowchart illustrating the steps of the wireless power transfer constant voltage, constant current, and constant power control method provided in this application embodiment, as follows: Figure 8 As shown, the steps of using the constant voltage, constant current, and constant power control method provided in this embodiment include: Step S801: First input Figure 1 Relevant circuit parameters, U dc L p R p C p0 L s C s R s , ω, δ2, I ref U ref P ref .

[0055] Step S802: Let C p =C p0 Detect the inverter output voltage U in and primary current I p Phase θ in1 Let C p =0.95C p0 Detect the inverter output voltage U in and primary current I p Phase θ in2 .

[0056] Step S803: Set θ in1 θ in2 Substituting into equations (10) and (11), the load R is identified. B Mutual induction M.

[0057] Step S804: Identify the load R B Substituting the mutual inductance M into equation (12) yields δ1, and the capacitance C of the adjustable capacitor is calculated using equation (13). p′ Adjust the adjustable capacitor value to C. p′ The system achieves a PT-symmetric state.

[0058] Step S805: Obtain the resulting load R B Substituting δ1 into equation (14), we obtain the load voltage, current, and power.

[0059] Step S806: Obtain the constant current mode duty cycle Dcc, constant voltage mode duty cycle Dcv and constant power mode duty cycle Dcp using equation (15).

[0060] The method described in this embodiment enables a constant-frequency, constant-output mechanism under dual-parameter perturbation. Unlike existing technologies that only address single-parameter (load or mutual inductance) perturbations, this invention constructs a system model that simultaneously considers both load and mutual inductance changes. It achieves constant-voltage, constant-current, or constant-power output at a fixed operating frequency, precisely meeting the actual operational needs of coal mines where equipment movement is frequent and operating conditions are complex. This overcomes the limitations of existing technologies that only consider single-parameter perturbations (load or mutual inductance), achieving constant-voltage, constant-current, and constant-power output for the first time under dual load and mutual inductance perturbations. It is applicable to, but not limited to, the complex operating conditions faced in actual coal mine operations, and has greater practical value.

[0061] Secondly, by adopting a single fixed topology, the system satisfies the PT symmetry condition by adjusting the primary-side compensation capacitor, giving the system anti-offset and high position robustness characteristics. Without any topology switching, the constant voltage, constant current or constant power output can be stably achieved on demand under the condition of dual-parameter disturbance of load and mutual inductance by simply adjusting the duty cycle D of the Buck-Boost converter. This fundamentally eliminates the technical pain points of transient impact, increased system complexity and increased control difficulty caused by topology switching.

[0062] Furthermore, it does not require the collection of any secondary side sampling data, the establishment of wireless communication links, or the use of complex parameter identification algorithms. It can achieve constant output control by relying solely on the phase detection of primary side voltage and current, which greatly simplifies the system control process and reduces the difficulty of system implementation and the risk of failure in the underground explosion-proof environment.

[0063] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The same or similar parts between the various embodiments can be referred to each other.

[0064] Embodiments of the present invention are described with reference to flowchart illustrations and / or block diagrams of methods and apparatus according to embodiments of the invention. It will be understood that each block of the flowchart illustrations and / or block diagrams, and combinations of blocks in the flowchart illustrations and / or block diagrams, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, special-purpose computer, embedded processor, or other programmable data processing terminal device to produce a machine, such that the instructions, which execute via the processor of the computer or other programmable data processing terminal device, generate instructions for implementing the flowchart illustrations. Figure 1 One or more processes and / or boxes Figure 1 A device that provides the functions specified in one or more boxes.

[0065] Although preferred embodiments of the present invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the embodiments of the present invention.

[0066] Finally, it should be noted that in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0067] The foregoing has provided a detailed description of the constant voltage, constant current, and constant power control method for fixed-frequency parity-time symmetric wireless power transfer provided by the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are 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 constant-voltage, constant-current, and constant-power control method for fixed-frequency, parity-time symmetric wireless power transfer, characterized in that, An application is made in a wireless power transmission system, the wireless power transmission system including a transmitter and a receiver, the transmitter including a transmitting coil, an adjustable capacitor, an inverter, and a voltage converter, the adjustable capacitor being connected in series with the transmitting coil, and the receiver including a receiving coil and a load, the method comprising: When the capacitance value of the adjustable capacitor is adjusted to a first capacitance value, a first phase difference between the output voltage of the inverter and the current of the transmitter is obtained; and when the capacitance value of the adjustable capacitor is adjusted to a second capacitance value, a second phase difference between the output voltage of the inverter and the current of the transmitter is obtained; wherein the first capacitance value and the second capacitance value are different. Based on the first phase difference, the second phase difference, and a preset load calculation model, the resistance value of the load is obtained, and based on the first phase difference, the second phase difference, and a preset mutual inductance calculation model, the mutual inductance value between the transmitting coil and the receiving coil is obtained. Based on the resistance value of the load and the mutual inductance value, the transmitter adjustment coefficient is obtained, and based on the transmitter adjustment coefficient, the target capacitance value of the adjustable capacitor is determined, and the capacitance value of the adjustable capacitor is adjusted to the target capacitance value so that the wireless power transmission system is in a parity-time symmetric state. The duty cycle of the voltage converter is controlled based on the transmitter adjustment coefficient, the resistance value of the load, the target operating mode of the wireless power transmission system, and the target output value of the target operating mode; wherein the target operating mode is one of constant current mode, constant voltage mode, and constant power mode.

2. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 1, characterized in that, Based on the transmitter regulation coefficient, the load resistance value, the target operating mode of the wireless power transmission system, and the target output value of the target operating mode, the duty cycle of the voltage converter is controlled, including: Based on the target working mode, the target duty cycle calculation model is determined from a variety of preset candidate duty cycle calculation models. Different candidate duty cycle calculation models correspond to different working modes. Based on the transmitter adjustment coefficient, the load resistance value, the target output value, and the target duty cycle calculation model, the target duty cycle corresponding to the target operating mode is obtained; The duty cycle of the voltage converter is controlled to the target duty cycle.

3. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 2, characterized in that, The various candidate duty cycle calculation models include a constant current duty cycle calculation model, a constant voltage duty cycle calculation model, and a constant power duty cycle calculation model. When the target operating mode is the constant current mode, the target duty cycle calculation model is the constant current duty cycle calculation model; When the target operating mode is the constant voltage mode, the target duty cycle calculation model is the constant voltage duty cycle calculation model; When the target operating mode is the constant power mode, the target duty cycle calculation model is the constant power duty cycle calculation model.

4. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 2, characterized in that, Based on the transmitter adjustment coefficient, the load resistance value, the target output value, and the target duty cycle calculation model, the target duty cycle corresponding to the target operating mode is obtained, including: The target duty cycle is obtained by inputting the transmitter adjustment coefficient, the load resistance value, the target output value, the input voltage of the wireless power transmission system, the parasitic internal resistance of the transmitter, the parasitic internal resistance of the receiver, the receiver reference coefficient, and the ratio of the transmitter coil to the receiver coil into the target duty cycle calculation model.

5. The control method according to claim 1, characterized in that, Based on the first phase difference, the second phase difference, and a preset load calculation model, the resistance value of the load is obtained, including: The first phase difference, the second phase difference, the parasitic internal resistance of the receiving end, the parasitic resistance of the transmitting end, the first reactance, the second reactance, and the reactance of the receiving end are input into the preset load calculation model to obtain the resistance value of the load; wherein, the first reactance is the reactance of the transmitting end when the adjustable capacitor is the first capacitance value, and the second reactance is the reactance of the transmitting end when the adjustable capacitor is the second capacitance value.

6. The control method according to claim 5, characterized in that, The preset load calculation model is as follows: in, The resistance value of the load; This is the first phase difference; This is the second phase difference; This refers to the parasitic internal resistance of the receiving end; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; This is the reactance at the receiving end.

7. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 1, characterized in that, The process of obtaining the mutual inductance value between the transmitting coil and the receiving coil based on the first phase difference, the second phase difference, and a preset mutual inductance calculation model includes: The first phase difference, the second phase difference, the parasitic resistance of the transmitting end, the first reactance, the second reactance, the reactance of the receiving end, and the frequency of the wireless power transmission system are input into the preset mutual inductance calculation model to obtain the mutual inductance value; wherein, the first reactance is the reactance of the transmitting end when the adjustable capacitor is the first capacitance value, and the second reactance is the reactance of the transmitting end when the adjustable capacitor is the second capacitance value.

8. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 7, characterized in that, The preset mutual inductance calculation model is as follows: in, Mutual inductance value; This is the first phase difference; This is the second phase difference; The parasitic internal resistance of the transmitting end; The first reactance; This is the second reactance; The reactance at the receiving end; The frequency of a wireless power transmission system.

9. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 1, characterized in that, Based on the resistance value of the load and the mutual inductance value, a transmitter adjustment coefficient is obtained, and based on the transmitter adjustment coefficient, a target capacitance value for the adjustable capacitor is determined, including: The resistance value of the load, the mutual inductance value, the receiver reference coefficient, the inductance of the transmitting coil, the inductance of the receiving coil, the reactance of the receiver, the parasitic internal resistance of the receiver, and the frequency of the wireless power transmission system are input into a preset parity-symmetric calculation model to obtain the transmitter adjustment coefficient. The target capacitance value is obtained based on the transmitter adjustment coefficient, the frequency of the wireless power transmission system, and the inductance of the transmitter coil.

10. The constant-voltage, constant-current, and constant-power control method for fixed-frequency parity-time symmetric wireless power transfer according to claim 9, characterized in that, The preset symmetric calculation model is as follows: in, This refers to the adjustment coefficient at the transmitting end; For the receiving end reference coefficient; The reactance at the receiving end; The frequency for wireless power transmission systems; For the inductance of the transmitting coil, The inductance of the receiving coil; The resistance value of the load; This represents the parasitic internal resistance of the receiving end.

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