A method for detecting and adjusting online parameter deviation of a wireless charging system

Abstract

The present disclosure belongs to the technical field of wireless charging, and specifically relates to an online parameter deviation detection and adjustment method for a wireless charging system, comprising: constructing a wireless charging system in which a trigger angle phase of a secondary-side full-bridge rectifier circuit lags behind a trigger angle phase of a primary-side inverter circuit by 90°; introducing a resistance offset correction term in the wireless charging system, calculating the phase angle of voltage and current when the wireless charging system is working at a constant voltage and stable manner, and obtaining a reactance offset value of each branch of the wireless charging system; judging whether the obtained reactance offset value exceeds a set threshold value, and if so, directly performing deviation detection according to the obtained reactance offset value; otherwise, continuing detection after adjusting a capacitor array until the obtained reactance offset value does not exceed the set threshold value.

Description

Technical Field

[0001] The present invention belongs to the technical field of wireless charging, and in particular relates to an online parameter deviation detection and adjustment method for a wireless charging system. Background Art

[0002] The statements in this section merely provide background information related to the present disclosure and do not necessarily constitute prior art.

[0003] In recent years, wireless power transmission has been widely used in communications, household appliances, medicine, electric vehicles, engineering equipment and other scenarios, and is suitable for occasions of all power levels. Wireless charging technology has the advantages of safety, reliability, flexibility, and no contact wear, and can cope with various complex working conditions. With the continuous development of the new energy vehicle industry, the number of electric vehicles in the world continues to increase, and the demand for electricity is also gradually increasing. The on-board battery of electric vehicles can be used as a mobile energy storage device to carry out two-way energy transfer with the power grid to achieve "peak shaving and valley filling" and other regulation, which is of positive significance to improving the stability and intelligence of the future energy Internet.

[0004] Based on the design of bidirectional wireless charging, a symmetrical compensation topology and control circuit are generally used, and the output power is changed by adjusting the phase shift angle and conduction angle of the control circuit. For high-power wireless charging systems such as electric vehicles, magnetic coupling resonant wireless power transmission is often used. The energy transmission coil and the compensation inductor and capacitor form a resonant circuit, so that the resonant circuits with the same frequency on the primary and secondary sides generate a strongly coupled magnetic field to achieve energy interaction. When the system is working, external interference and changes in the circuit's own conditions will cause changes in circuit device parameters, and the device itself has parameter errors. When the parameters of the compensation circuit are greatly offset, the system will be detuned, resulting in a decrease in output power and transmission efficiency. Summary of the invention

[0005] In order to solve the above problems, the present disclosure proposes a method for online parameter deviation detection and adjustment of a wireless charging system, analyzes the phenomenon of circuit parameter deviation, and uses a capacitor array to adjust the compensation circuit to ensure efficient transmission of electric energy and maximum power output of the wireless charging system, thereby realizing online detection and dynamic adjustment of circuit parameters.

[0006] According to some embodiments, the solution of the present disclosure provides a method for online parameter deviation detection and adjustment of a wireless charging system, which adopts the following technical solutions:

[0007] A method for detecting and adjusting online parameter deviation of a wireless charging system, comprising:

[0008] Construct a wireless charging system in which the trigger angle phase of the secondary-side full-bridge rectifier circuit lags behind the trigger angle phase of the primary-side inverter circuit by 90°;

[0009] A resistance offset correction term is introduced into the wireless charging system to calculate the phase angle of voltage and current when the wireless charging system is working stably, thereby reflecting the influence of line internal resistance and parasitic resistance, making the circuit model more accurate, and obtaining the reactance offset value of each branch of the wireless charging system;

[0010] It is determined whether the obtained reactance offset value exceeds the set threshold value. If so, deviation detection is performed directly according to the obtained reactance offset value; otherwise, the capacitor array is adjusted and detection is continued until the obtained reactance offset value does not exceed the set threshold value.

[0011] As a further technical limitation, the wireless charging system adopts a magnetically coupled resonant wireless charging system to achieve bidirectional energy transmission.

[0012] Furthermore, the primary side of the wireless charging system is connected to a single-phase industrial frequency mains power supply, which passes through the primary side rectification and filtering unit, the high-frequency inverter unit and the primary side compensation network in sequence and is input into the primary side coil; under the inductive coupling of the magnetic field, after the electric energy is transmitted to the secondary side coil, it passes through the secondary side compensation network and the rectification and filtering and power conversion unit in sequence to supply power to the load.

[0013] Furthermore, the high-frequency inverter unit adopts a fully-controlled full-bridge high-frequency inverter, the primary compensation network and the secondary compensation network both adopt resonant networks, and the secondary coil adopts a fully-controlled full-bridge rectifier.

[0014] As a further technical limitation, the parameters of the wireless charging system are determined including current, voltage, impedance, resonance, current phase angle and output power in the primary coil and the secondary coil.

[0015] As a further technical limitation, the resistance offset correction term is related to the line internal resistance, input voltage, output voltage, frequency and compensation inductance in the wireless charging system; the resistance offset correction term reflects the influence of internal resistance on circuit characteristics and improves the accuracy of analysis.

[0016] As a further technical limitation, the phase difference between two signals of the same frequency is obtained by phase measurement, and the measurement of the phase difference includes two methods: analog measurement and digital measurement.

[0017] Furthermore, the digital quantity measurement includes a phase-time conversion method and a phase-voltage conversion method, that is, the phase is converted into a time interval or voltage for measurement.

[0018] Furthermore, the phase angle of each current is obtained by measuring the phase difference between each current and the input voltage, and the inductive or capacitive offset of each branch is calculated according to the expression to perform real-time judgment and adjustment.

[0019] As a further technical limitation, in the process of adjusting the capacitor array, the primary side of the wireless charging system adopts a capacitor array structure to compensate for the inductive or capacitive deviation of the circuit; in the capacitor array, each sub-capacitor is configured with a switch, and a series capacitor group, a parallel capacitor group or a capacitor not connected to the circuit is formed according to the state of the switch; the capacitor array of the secondary side of the wireless charging system is symmetrical with the capacitor array of the primary side, and the series or parallel method adopted is the same as that of the primary side.

[0020] Furthermore, according to the parameters of the wireless charging system, the capacitive reactance value of the sub-capacitor in the capacitor array is set. When the inductive offset in the wireless charging system is too large and exceeds the set threshold, the inductive offset is compensated by increasing the corresponding capacitive reactance value. If the capacitive offset in the wireless charging system is too large and exceeds the set threshold, the corresponding capacitive reactance value is reduced for compensation.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The present invention adopts a capacitor array to adjust the compensation circuit to ensure efficient transmission of system electric energy and maximum power output. The online parameter deviation detection and adjustment method of the wireless charging system under the condition of maximum output power realizes high-efficiency charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present disclosure are used to provide a further understanding of the present disclosure. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation on the present disclosure.

[0024] Figure 1 is a flow chart of a method for online parameter deviation detection and adjustment of a wireless charging system in an embodiment of the present disclosure;

[0025] Figure 2 is a structural block diagram of a magnetically coupled resonant wireless charging system in an embodiment of the present disclosure;

[0026] Figure 3 is an equivalent circuit diagram of a wireless charging system in an embodiment of the present disclosure;

[0027] Figure 4 is a schematic diagram of the relationship between reactance offset and phase angle in an embodiment of the present disclosure;

[0028] FIG5( a ) is a schematic diagram of a phase-voltage conversion method in an embodiment of the present disclosure;

[0029] FIG5( b ) is a schematic diagram of the phase-time conversion method in an embodiment of the present disclosure;

[0030] FIG6( a ) is a waveform diagram of the phase-voltage conversion method in an embodiment of the present disclosure;

[0031] FIG6( b ) is a waveform diagram of the phase-time conversion method in an embodiment of the present disclosure;

[0032] Figure 7 is a structural diagram of a capacitor array in an embodiment of the present disclosure. DETAILED DESCRIPTION

[0033] The present disclosure is further described below in conjunction with the accompanying drawings and embodiments.

[0034] It should be noted that the following detailed descriptions are all illustrative and are intended to provide further explanation of the present disclosure. Unless otherwise specified, all technical and scientific terms used herein have the same meanings as those commonly understood by those skilled in the art to which the present disclosure belongs.

[0035] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present disclosure. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprising" and / or "including" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0036] In the absence of conflict, the embodiments in the present disclosure and the features in the embodiments may be combined with each other.

[0037] Example

[0038] Embodiment 1 of the present disclosure introduces a method for detecting and adjusting online parameter deviations of a wireless charging system.

[0039] like Figure 1 The method for detecting and adjusting the online parameter deviation of a wireless charging system shown in FIG. 1 includes the following steps: firstly, the electrical parameters of the system are determined, and the trigger angle phase of the secondary-side full-bridge rectifier circuit is made to lag behind the trigger angle phase of the primary-side inverter circuit by 90°, and then the resistance correction term ρ of the four branches is calculated. x , when the system is working stably, the voltage and current phase angles are obtained to obtain L A , L C , L D , L F The reactance offset value determines whether each offset value exceeds the threshold. If it is within the threshold, continue to detect without making any adjustments. If it exceeds the threshold, adjust the capacitor array as needed and continue to detect until the system stops working.

[0040] In this embodiment, the wireless charging system adopts Figure 2The magnetic coupling resonant wireless charging system shown can realize bidirectional energy transmission, and the structure adopts a symmetrical design; specifically, the primary side of the system is connected to the single-phase industrial frequency mains, and undergoes a series of power electronic transformations such as rectification, filtering and high-frequency inversion. The inverter link adopts a fully controlled full-bridge high-frequency inverter. The converted high-frequency alternating current passes through the resonant network and is input into the primary side coil. Under the inductive coupling of the magnetic field, the electric energy is transmitted to the secondary side coil, and the usable working current is obtained through the resonant network and rectification and filtering to supply the load. The secondary side adopts a fully controlled full-bridge rectification method. There is generally a communication device between the primary side and the secondary side of the system to realize information interaction, so as to adjust the control mode of the power electronic device in time. Because there is a large gap between the energy transmission coils, the coupling coefficient of the power transmission part is small. In order to ensure the output of appropriate power and efficiency during charging, a symmetrical dual LCC compensation topology is adopted to balance the reactive power. The wireless communication module can realize the interaction of information between the primary side and the secondary side of the system.

[0041] The power transmission circuit of the wireless charging system is simplified, and the full-bridge inverter output on the primary side of the circuit can be equivalent to a voltage source U in , the input voltage of the rectifier circuit on the load side of the power supply can be equivalent to U out , and get Figure 3 The simplified equivalent circuit diagram of the wireless charging system is shown in FIG. 1 , wherein A, B, C, D, E, and F represent the deviations between the impedance parameters of the six corresponding branches and the rated values, including resistance and reactance. The resonant frequency of the circuit is 85 kHz, and L f1 , L f2 , L1, L2, C f1 , C f2 , C1, C2 are compensation inductors and capacitors, m represents the mutual inductance between the primary and secondary coils, and the circuit meets the resonance condition:

[0042]

[0043] Under resonant conditions, when the components of the circuit are at rated values, there are four current expressions:

[0044]

[0045] Since branches B and E are parallel capacitors, their parameter offset errors can be approximately ignored. The current deviations caused by branches A, C, D, and F are discussed separately and then superimposed to obtain the current expression considering component parameter offset:

[0046]

[0047] Let U in The phase angle is 0°, α1, α2, α3, and α4 represent I Lf1 , I1, I2, ILf2 The phase angles of the four currents, and U out The phase angle is θ. First, analyze the reactance offset and introduce L A , L C , L D , L F The four parameters, when they are positive, represent the inductive offset of the branch, and when they are negative, represent the capacitive offset of the branch. The equivalent capacitance can be expressed by the inductance parameter as The expressions of the four currents expressed by the above parameters are obtained:

[0048]

[0049] According to the input and output voltage expressions obtained by phase shift control, we can know that and are the phase difference of the two bridge arm driving signals of the primary side and the secondary side respectively, and the relative phase difference between the two is θ. i with U o represents the amplitude of the voltage source on both sides, that is Then we can obtain the active power P output when there is reactance offset. out_mist :

[0050]

[0051] That is, when θ=+ / -90°, the input power reaches the maximum, and when θ=-90°, the power is transmitted in the forward direction.

[0052] For resistance offset, when the offset is purely resistive and θ = -90°, the current change phase caused by the resistance parameter offset is in phase or in reverse phase with the rated current. Since the resistive offset term is positive, I Lf1 , I1, I2, I Lf2 The correction term ρ for the effect of the purely resistive offset flowing through the branch Lf1 , 1_A , 2_F , Lf2 , ρ Lf1 The resistance parameter deviation correction term ρ of branches C and F is Lf1_C and ρ Lf1_F Composition, ρ Lf2 The resistance parameter deviation correction term ρ of branches A and D is Lf2_A and ρ Lf2_D The expression of the correction term group is:

[0053]

[0054] The current expression after adding the resistance offset correction term is:

[0055]

[0056] Correction term ρ x Value and line internal resistance, input voltage U i , output voltage U o , frequency ω and compensation inductance L f1 , L f2 Generally, the internal resistance of the line is fixed, and other parameters can also be determined according to the actual working conditions, and the correction coefficient term is taken as ρ Lf1_C =0.28,ρ Lf1_F =0.47,ρ 1_A =0.30,ρ 2_F =0.96, ρ Lf2_A =0.37, ρ Lf2_D =1.74. Based on the analysis of inductive or capacitive offset in the previous article, the expression of current phase angle is obtained:

[0057]

[0058] Then the calculation results of the offset of the four branches can be obtained:

[0059]

[0060] Figure 4 The figure is a diagram showing the relationship between the phase angle and the offset rate obtained from the above formula. The offset rate represents the ratio between the parameter change and the set component rating. The offset of branch C has a greater impact on α1, which is the input impedance angle, than that of branch F. When the offset of branch A is capacitive, α2 is greater than -90°, otherwise it is less than -90°. When the offset of branch F is capacitive, α3 is less than 0°, otherwise it is greater than 0°. The offset of branch D has a greater impact on α4 than the offset of branch A.

[0061] In the compensation topology circuit, the frequency of the voltage and current is the same, and the phase difference between the two signals of the same frequency can be obtained by phase measurement. The measurement of phase difference is divided into two types of measurement methods: analog and digital. Generally, digital phase measurement method is used to achieve higher detection accuracy.

[0062] The digital methods of phasor measurement include phase-time conversion method and phase-voltage conversion method, that is, the phase can be converted into time interval or voltage for measurement. The measurement process is: first, after amplification and shaping by the voltage comparator, the voltage and current waveforms are converted into the required two voltage square wave signals u1 and u2. Figure 5 (a) is the principle diagram of the phase-voltage conversion method. The square wave signal is differentiated to obtain two sharp pulses corresponding to the negative zero-crossing instant of the measured signal. The two sets of negative pulses trigger the phase detector, so that its output period is T and the width is T x The square wave has an amplitude of U a After filtering, the average value of this square wave is in, It indicates the phase difference between the measured current and the input voltage. Figure 6(a) is the waveform diagram of the phase-voltage conversion measurement method, and the phase difference expression is obtained:

[0063]

[0064] Figure 5(b) is a schematic diagram of the phase-time conversion method. Similarly, two voltage signals are processed by the phase detector and the time interval T of the phase detector is counted by the counting method. x The measurement is performed, and the time scale pulse period is T c , we can get T x The count value N within the time is counted using a decimal counter, T c With period T satisfying n is a positive integer, and FIG6(b) is a waveform diagram of the phase-time conversion measurement method, and the phase difference expression is obtained:

[0065]

[0066] The phase of the two signals can be determined using a D flip-flop.

[0067] In the process of adjusting and compensating the circuit parameters, the primary side adopts Figure 7 The capacitor array structure shown in the figure is used to compensate for the inductive or capacitive deviation of the circuit. Each sub-capacitor is equipped with a switch. The switch has three states. When connected to the ① branch line, it forms a series capacitor group of C1, and when connected to the ② branch line, it forms a series capacitor group of C f1 The parallel capacitor group, if the switch is in the middle position, the sub-capacitor is not connected to the circuit. The secondary capacitor array structure is symmetrical with the primary side, and the corresponding series and parallel connection methods are the same as the primary side. According to the specific parameters of the circuit, the value of the capacitor array sub-capacitor is set. In order to make the value step size 1, the sub-capacitor value is s×2 a , where s is the unit length and a is the component C p or C f1 The number of sub-capacitors is an integer multiple of the unit length. If the system inductive offset is too large and exceeds the threshold, then according to Increase the corresponding C x value to compensate for the inductive offset. If the capacitive offset is too large and exceeds the threshold, reduce the corresponding C x value to compensate.

[0068] This embodiment uses a capacitor array to adjust the compensation circuit to ensure efficient transmission of electric energy and maximum power output when the system is charging. The online parameter deviation detection and adjustment method of the wireless charging system under the condition of maximum output power realizes high-efficiency charging.

[0069] The above description is only a preferred embodiment of the present disclosure and is not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. A method for detecting and adjusting online parameter deviation of a wireless charging system, characterized in that: include: Determine the parameters of the wireless charging system and construct a wireless charging system in which the trigger angle phase of the secondary-side full-bridge rectifier circuit lags behind the trigger angle phase of the primary-side inverter circuit by 90°; Introducing a resistance offset correction term into the wireless charging system, calculating the phase angle of voltage and current when the wireless charging system is working stably at a constant voltage, and obtaining the reactance offset value of each branch of the wireless charging system; Determine whether the obtained reactance offset value exceeds a set threshold value, and if so, continue to detect after adjusting the capacitor array until the obtained reactance offset value does not exceed the set threshold value; Otherwise, deviation detection is performed directly based on the obtained reactance offset value; Among them, the resistance offset correction term is The phase angle of the current is The obtained reactance offset values ​​of each branch of the wireless charging system are Among them, ρ Lf1 Indicates the introduction of I Lf Correction term for the purely resistive offset effect of the branch; ρ Lf1_C represents the resistance parameter deviation correction term of branch C; ρ Lf1_F Indicates the resistance parameter deviation correction item of the F branch; C indicates the deviation between the impedance parameter of the C branch and the rated value; U i represents input voltage; ω represents frequency; L f1 represents the first compensation inductor; F represents the deviation between the F branch impedance parameter and the rated value; m represents the mutual inductance between the primary and secondary coils; L f2 represents the second compensation inductance; ρ 1_A It represents the correction term for the pure resistive offset effect introduced when I1 flows through the branch; A represents the deviation between the impedance parameter of branch A and the rated value; U o Represents the output voltage; ρ 2_F represents the correction term for the purely resistive offset effect of I2 flowing through the branch; ρ Lf2 Indicates the introduction of I Lf2 Correction term for the purely resistive offset effect of the branch; ρ Lf2_A represents the resistance parameter deviation correction term of branch A; ρ Lf2_D It represents the resistance parameter deviation correction item of the D branch; D represents the deviation between the impedance parameter of the D branch and the rated value; α1 represents I Lf1 Phase angle of branch current; L F Indicates the inductance offset of the F branch; L C represents the inductance offset of the C branch; α2 represents the phase angle of the I1 branch current; L A represents the inductance offset of branch A; α3 represents the phase angle of branch I2 current; α4 represents I Lf2 Phase angle of branch current; L D Indicates the inductance offset of the D branch; In the process of adjusting the capacitor array, the primary side of the wireless charging system adopts a capacitor array structure to compensate for the inductive or capacitive deviation of the circuit; in the capacitor array, each sub-capacitor is configured with a switch, and a series capacitor group, a parallel capacitor group or a capacitor not connected to the circuit is formed according to the different states of the switch; the capacitor array of the secondary side of the wireless charging system is symmetrical with the capacitor array of the primary side, and the series or parallel mode adopted is the same as that of the primary side.

2. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 1, characterized in that: The wireless charging system adopts a magnetic coupling resonance type wireless charging system to achieve bidirectional energy transmission.

3. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 2, characterized in that: The primary side of the wireless charging system is connected to a single-phase industrial frequency mains power supply, which passes through a primary side rectification and filtering unit, a high-frequency inverter unit and a primary side compensation network in sequence and is input into a primary side coil; under the inductive coupling of a magnetic field, after the electric energy is transmitted to the secondary side coil, it passes through a secondary side compensation network and a rectification and filtering and power conversion unit in sequence to supply power to a load.

4. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 3, characterized in that: The high-frequency inverter unit adopts a fully-controlled full-bridge high-frequency inverter, the primary compensation network and the secondary compensation network both adopt resonant networks, and the secondary coil adopts a fully-controlled full-bridge rectifier.

5. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 1, characterized in that: The parameters of the wireless charging system are determined including current, voltage, impedance, resonance, current phase angle and output power in the primary coil and the secondary coil.

6. A method for online parameter deviation detection and adjustment of a wireless charging system as claimed in claim 1, characterized in that: The resistance offset correction term is related to the line internal resistance, input voltage, output voltage, frequency and compensation inductance in the wireless charging system; the resistance offset correction term reflects the influence of internal resistance on circuit characteristics and improves the accuracy of analysis.

7. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 1, characterized in that: The phase difference between two signals of the same frequency is obtained by phase measurement, and the measurement of the phase difference includes two methods: analog measurement and digital measurement.

8. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 7, characterized in that: The digital quantity measurement includes a phase-time conversion method and a phase-voltage conversion method, that is, the phase is converted into a time interval or voltage for measurement.

9. A method for online parameter deviation detection and adjustment of a wireless charging system as claimed in claim 1, characterized in that: By measuring the phase difference between each current and the input voltage to obtain the phase angle of each current, the inductive or capacitive offset value of each branch can be obtained for real-time judgment and adjustment.

10. A method for detecting and adjusting online parameter deviation of a wireless charging system as claimed in claim 1, characterized in that: According to the parameters of the wireless charging system, the capacitive reactance value of the sub-capacitor in the capacitor array is set. When the inductive offset in the wireless charging system is too large and exceeds the set threshold, the inductive offset is compensated by increasing the corresponding capacitive reactance value. If the capacitive offset in the wireless charging system is too large and exceeds the set threshold, the corresponding capacitive reactance value is reduced for compensation.

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