CN111082541B - Control method and device of mobile wireless power transmission system - Google Patents
Control method and device of mobile wireless power transmission system Download PDFInfo
- Publication number
- CN111082541B CN111082541B CN201911337896.1A CN201911337896A CN111082541B CN 111082541 B CN111082541 B CN 111082541B CN 201911337896 A CN201911337896 A CN 201911337896A CN 111082541 B CN111082541 B CN 111082541B
- Authority
- CN
- China
- Prior art keywords
- frequency
- transmission system
- mobile wireless
- circuit
- power transmission
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Images
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/70—Circuit arrangements or systems for wireless supply or distribution of electric power involving the reduction of electric, magnetic or electromagnetic leakage fields
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Power Engineering (AREA)
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Transmitters (AREA)
Abstract
The invention relates to a control method and a control device of a mobile wireless power transmission system. The control method comprises the following steps: constructing a system equivalent circuit of the mobile wireless power transmission system, wherein the system equivalent circuit comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit; sequentially inputting a plurality of high-frequency harmonic signals to a system equivalent circuit of the mobile wireless electric energy transmission system, and collecting output voltage and output current of the system equivalent circuit, wherein the frequencies of the high-frequency harmonic signals are different; and in the system equivalent circuit, determining the optimal working frequency of the mobile wireless power transmission system according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal.
Description
Technical Field
The present invention relates to the field of wireless charging technologies, and in particular, to a method and an apparatus for controlling a mobile wireless power transmission system.
Background
The magnetic coupling resonant wireless power transmission system is a nonlinear multi-parameter cross-influenced coupling system, the change or deviation of any parameter can cause the change of the resonant frequency of the system, the transmission performance of the system is influenced, and the position of a primary side and the position of a secondary side in a mobile charging system are not fixed, so that the problem is more serious. The high-efficiency transmission of the magnetic coupling resonant wireless power transmission system mainly depends on whether the system can work in a resonant state, namely whether the system working frequency is consistent with the resonant frequency. Conventional system tuning methods are primarily considered from two aspects: firstly, keeping the working frequency of the system unchanged, and dynamically adjusting the structural parameters of the system; and secondly, the working frequency of the system is dynamically adjusted without changing the structural parameters of the system, namely frequency tracking control. The first method needs to add a tuning circuit in the resonant topology, which is complicated. The second method, frequency tracking control, mainly uses phase-locked loop to realize frequency tracking by detecting the current and voltage of the transmitting end or the receiving end, or uses disturbance observation method. The analog phase-locked loop chip has the defects of poor noise immunity, low reliability and the like. Digital phase lock control requires corresponding hardware circuit design, increasing system cost and complexity. The disturbance observation method can cause the system to vibrate near the optimal resonant frequency point all the time, and the stable work cannot be realized.
Disclosure of Invention
Accordingly, the present invention provides a method and an apparatus for controlling a mobile wireless power transmission system, and solves the problem caused by inconsistency between the operating frequency and the resonant frequency of the system due to the parameter change in the system.
The embodiment of the invention provides a control method of a mobile wireless power transmission system, which comprises the following steps:
constructing a system equivalent circuit of the mobile wireless power transmission system, wherein the system equivalent circuit comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit;
sequentially inputting a plurality of high-frequency harmonic signals to a system equivalent circuit of the mobile wireless electric energy transmission system, and collecting output voltage and output current of the system equivalent circuit, wherein the frequencies of the high-frequency harmonic signals are different;
and in the system equivalent circuit, determining the optimal working frequency of the mobile wireless power transmission system according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal.
In one embodiment, the determining, in the equivalent circuit, an optimal resonant frequency of the mobile wireless power transmission system according to a plurality of the high-frequency harmonic signals and the output voltage and the output current corresponding to each of the high-frequency harmonic signals includes:
constructing a T-shaped equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit;
determining key parameters of the T-shaped equivalent circuit according to the high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
determining the primary equivalent impedance, the secondary equivalent impedance and the phasor equation of the mutual inductance equivalent circuit;
determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency;
judging whether the mobile wireless power transmission system is in an over-coupling state or not according to the obtained at least one resonant frequency;
if so, taking the split frequency in the resonant frequency which enables the mobile wireless power transmission system to have the maximum output power as the optimal working frequency;
otherwise, the natural resonant frequency of the resonant frequency mobile wireless power transmission system is taken as the optimal working frequency.
In one embodiment, the determining whether the mobile wireless power transmission system is in an over-coupled state according to the obtained at least one resonant frequency includes:
judging whether the number of the resonance frequencies obtained by solving is greater than 1;
if so, judging that the mobile wireless electric energy transmission system is in an over-coupling state;
otherwise, the mobile wireless electric energy transmission system is judged to be in a normal working state.
In one embodiment, the dividing a split frequency of the resonance frequency, which causes the mobile wireless power transmission system to have the maximum output power, as the optimal operating frequency includes:
calculating the output power of the mobile wireless power transmission system working at each split frequency;
comparing the output powers, and determining the maximum output power and the splitting frequency corresponding to the maximum output power;
and taking the splitting frequency corresponding to the large output power as the optimal working frequency.
In one embodiment, the determining a high-order equation about the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation includes:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
In one embodiment, the primary equivalent input impedance of the mutual inductance equivalent circuit
Zin＝Rin+jXin
Wherein
RinIs the real part, X, of the equivalent input impedance of the primary sideinIs the imaginary part of the equivalent input impedance of the primary side, omega is the resonance frequency, M is the primary and secondary mutual inductance, LpIs a primary side inductance, LsIs a secondary inductor, CpIs a secondary inductor, CsCompensating the capacitance for the secondary side, R2Is the real part of the equivalent impedance of the secondary side,
is the imaginary part of the equivalent impedance of the secondary side except the inductance, and j is the imaginary unit.
In one embodiment, the control method further includes:
and generating a driving signal for controlling the switching frequency of the high-frequency inverter circuit according to the optimal working frequency, wherein the frequency of the driving signal is equal to the optimal working frequency.
In one embodiment, the mobile wireless power transmission system is provided with 5 high-frequency harmonic signals in sequence.
In one embodiment, the determining key parameters of the T-shaped equivalent circuit according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal includes:
establishing a quinary linear equation for the T-shaped equivalent circuit of the resonance compensation circuit by utilizing kirchhoff voltage law;
and substituting each high-frequency harmonic signal, the output voltage and the output current corresponding to each high-frequency harmonic signal into the quintuple equation, and calculating to obtain the key parameters of the T-shaped equivalent circuit.
Based on the same inventive concept, an embodiment of the present invention further provides a control device for a mobile wireless power transmission system, including:
the system equivalent circuit is an equivalent circuit of the mobile wireless electric energy transmission system and comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit;
the detection circuit is used for acquiring a plurality of groups of output voltages and output currents of the mobile wireless power transmission system, and each output voltage and each output current corresponds to an input high-frequency harmonic signal;
and the data processing circuit is electrically connected with the detection circuit and used for determining the optimal working frequency of the mobile wireless power transmission system according to a plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal in the equivalent circuit and providing the optimal working frequency to the frequency control circuit so that the frequency control circuit generates a driving signal for controlling the switching frequency of the high-frequency inverter circuit according to the optimal working frequency, wherein the frequency of the driving signal is equal to the optimal working frequency.
In one embodiment, the data processing circuit comprises:
the modeling unit is used for constructing a T-shaped equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit;
the first calculation unit is electrically connected with the modeling unit and the detection circuit respectively and used for determining key parameters of the T-shaped equivalent circuit according to a plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
the second calculation unit is electrically connected with the modeling unit and the first calculation unit respectively and is used for determining a primary equivalent impedance, a secondary equivalent impedance and a phasor equation of the mutual inductance equivalent circuit, determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency;
and the judging unit is electrically connected with the two calculating units and is used for judging whether the mobile wireless power transmission system is in an over-coupling state or not according to the obtained at least one resonant frequency, if so, the splitting frequency in the resonant frequency enabling the mobile wireless power transmission system to have the maximum output power is taken as the optimal working frequency, and otherwise, the inherent resonant frequency of the mobile wireless power transmission system with the resonant frequency is taken as the optimal working frequency.
In one embodiment, when the mobile wireless power transmission system is in a normal working state, one of the resonant frequencies is obtained according to a high-order equation of the resonant frequency, and is an inherent resonant frequency of the mobile wireless power transmission system;
when the mobile wireless power transmission system is in an over-coupling state, two or three resonant frequencies are obtained according to a high-order equation of the resonant frequencies, wherein the natural resonant frequency of one mobile wireless power transmission system is the splitting frequency of the other mobile wireless power transmission system.
In one embodiment, the second calculating unit is configured to determine a higher-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameter of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation, and is specifically configured to:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
To sum up, the embodiment of the invention provides a control method and a control device for a mobile wireless power transmission system. The control method comprises the following steps: constructing a system equivalent circuit of the mobile wireless power transmission system, wherein the system equivalent circuit comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit; sequentially inputting a plurality of high-frequency harmonic signals to a system equivalent circuit of the mobile wireless electric energy transmission system, and collecting output voltage and output current of the system equivalent circuit, wherein the frequencies of the high-frequency harmonic signals are different; and in the system equivalent circuit, determining the optimal working frequency of the mobile wireless power transmission system according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal. In the invention, the parameters of the coupling loop element in the system equivalent circuit of the wireless power transmission system are quickly identified by using a control algorithm only through the detection of the output voltage and the output current, and the optimal working frequency of the system at the moment is determined.
Drawings
Fig. 1 is a flowchart illustrating a control method of a mobile wireless power transmission system according to an embodiment of the present invention;
fig. 2 is a schematic diagram of an exemplary mobile wireless power transmission system;
fig. 3 is a schematic diagram of a T-type equivalent circuit of a resonance compensation circuit according to an embodiment of the present invention;
FIG. 4 is a schematic diagram of a mutual inductance equivalent circuit of the resonance compensation circuit according to the embodiment of the present invention;
fig. 5 is a flowchart illustrating another control method for a mobile wireless power transmission system according to an embodiment of the present invention;
fig. 6 is a schematic structural diagram of a control device of a mobile wireless power transmission system according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein, but rather should be construed as broadly as the present invention is capable of modification in various respects, all without departing from the spirit and scope of the present invention.
Referring to fig. 1, an embodiment of the present invention provides a method for controlling a mobile wireless power transmission system, including:
step S110, constructing a system equivalent circuit of the mobile wireless electric energy transmission system, wherein the system equivalent circuit comprises a power frequency rectification circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit;
step S120, sequentially inputting a plurality of high-frequency harmonic signals for a system equivalent circuit of the mobile wireless power transmission system, and collecting output voltage and output current of the system equivalent circuit, wherein the frequencies of the high-frequency harmonic signals are different;
step S130, in the system equivalent circuit, determining an optimal operating frequency of the mobile wireless power transmission system according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal.
Referring to fig. 2, the structure of the conventional mobile wireless power transmission system includes: power frequency rectifier circuit, high frequency inverter circuit, resonance compensation circuit, frequency control circuit. The power frequency rectifying circuit is used for generating direct-current voltage; the high-frequency inverter circuit is used for generating high-frequency current; the resonance compensation circuit is used for forming magnetic circuit coupling and realizing wireless transmission of energy; the frequency control circuit is used for realizing the optimal adjustment of the working frequency of the system. According to the magnetic resonance theory, when the working frequency is consistent with the resonance frequency, the system can obtain the maximum transmission efficiency conversion. In practical application, however, the load parameters, mutual inductance parameters and coupling coefficients in the system will change with different positions, thereby causing the natural resonant frequency of the system to shift. Therefore, in order to ensure the output power and transmission efficiency of the system, the operating frequency of the system needs to be controlled in real time to ensure the consistency with the resonant frequency.
According to the method, firstly, the wireless power transmission system is equivalently simplified to obtain the most basic component combination representing the working state of the circuit, on the basis, high-frequency harmonic voltages with different frequencies are applied to the equivalent circuit of the system, the output voltage and the output current of the system are measured, and then the resonant frequency, namely the optimal working frequency, of the system in the current state is calculated according to the output voltage and the output current. And finally, the control circuit works at the optimal working frequency, so that the circuit works at the maximum transmission efficiency.
Referring to fig. 3 and 4, in one embodiment, the determining an optimal resonant frequency of the mobile wireless power transmission system according to a plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each of the high-frequency harmonic signals in the equivalent circuit includes:
constructing a T-shaped equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit;
determining key parameters of the T-shaped equivalent circuit according to the high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
determining the primary equivalent impedance, the secondary equivalent impedance and the phasor equation of the mutual inductance equivalent circuit;
determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency;
judging whether the mobile wireless power transmission system is in an over-coupling state or not according to the obtained at least one resonant frequency;
if so, taking the split frequency in the resonant frequency which enables the mobile wireless power transmission system to have the maximum output power as the optimal working frequency;
otherwise, the natural resonant frequency of the resonant frequency mobile wireless power transmission system is taken as the optimal working frequency.
In this embodiment, a T-type equivalent circuit and a mutual inductance equivalent circuit for constructing the resonance compensation circuit are first established according to the working principle of the resonance compensation circuit. Secondly, injecting different high-frequency harmonic signals into the input end of the system, measuring the voltage and current values in the circuit in real time, and calculating the key parameters of the resonance compensation circuit in the current state according to the established system equivalent circuit. Then, determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency; and judging whether the system works in an over-coupling state, if not, selecting the inherent resonant frequency of the coupling circuit as the optimal working frequency of the system, and outputting the PWM driving signal of the high-frequency inverter circuit through the frequency control circuit. If the system is in an over-coupling state, comparing the output power corresponding to each splitting frequency of the current system, selecting the splitting frequency with the maximum output power as the optimal working frequency of the system, and outputting the optimal working frequency as a driving signal of the high-frequency inverter circuit through the frequency control circuit.
In one embodiment, the determining whether the mobile wireless power transmission system is in an over-coupled state according to the obtained at least one resonant frequency includes:
judging whether the number of the resonance frequencies obtained by solving is greater than 1;
if so, judging that the mobile wireless electric energy transmission system is in an over-coupling state;
otherwise, the mobile wireless electric energy transmission system is judged to be in a normal working state.
In this embodiment, when the mobile wireless power transmission system is in a normal operating state, one of the resonant frequencies is obtained according to the high order equation of the resonant frequency, and is the inherent resonant frequency of the mobile wireless power transmission system;
when the mobile wireless power transmission system is in an over-coupling state, two or three resonant frequencies are obtained according to a high-order equation of the resonant frequencies, wherein the natural resonant frequency of one mobile wireless power transmission system is the splitting frequency of the other mobile wireless power transmission system.
In one embodiment, the dividing a split frequency of the resonance frequency, which causes the mobile wireless power transmission system to have the maximum output power, as the optimal operating frequency includes:
calculating the output power of the mobile wireless power transmission system working at each split frequency;
comparing the output powers, and determining the maximum output power and the splitting frequency corresponding to the maximum output power;
and taking the splitting frequency corresponding to the large output power as the optimal working frequency.
In one embodiment, the determining a high-order equation about the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation includes:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
In one embodiment, the primary equivalent input impedance of the mutual inductance equivalent circuit
Zin＝Rin+jXin
Wherein
RinIs the real part, X, of the equivalent input impedance of the primary sideinIs the imaginary part of the equivalent input impedance of the primary side, omega is the resonance frequency, M is the primary and secondary mutual inductance, LpIs a primary side inductance, LsIs a secondary inductor, CpIs a secondary inductor, CsCompensating the capacitance for the secondary side, R2Is the real part of the equivalent impedance of the secondary side,
is the imaginary part of the equivalent impedance of the secondary side except the inductance, and j is the imaginary unit.
In one embodiment, the control method further includes:
and generating a driving signal for controlling the switching frequency of the high-frequency inverter circuit according to the optimal working frequency, wherein the frequency of the driving signal is equal to the optimal working frequency.
In one embodiment, the mobile wireless power transmission system provides 5 high-frequency harmonic signals in sequence, and the determining key parameters of the T-shaped equivalent circuit according to the high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal includes:
establishing a quinary linear equation for the T-shaped equivalent circuit of the resonance compensation circuit by utilizing kirchhoff voltage law;
and substituting each high-frequency harmonic signal, the output voltage and the output current corresponding to each high-frequency harmonic signal into the quintuple equation, and calculating to obtain the key parameters of the T-shaped equivalent circuit.
In order to better illustrate the technical solution of the present invention, the following examples are set forth in detail.
In the T-type equivalent circuit, a square wave voltage source is used for equivalently replacing high-frequency inversion output in front of a resonance compensation circuit, and a resonance coupling circuit part is equivalent according to a coupling mode principle, wherein Cp、Lp、Ls、CsRespectively a primary side series capacitor, a primary side inductor, a secondary side parallel capacitor and a secondary side inductor, M is the original secondary side mutual inductance, Rp、Rs、 R0Respectively is a primary equivalent resistor, a secondary equivalent resistor, an equivalent load resistor, Up、U0Respectively the output voltage of the inverter and the voltage across the load, Ip、IsAnd I0Primary side inductive current, secondary side inductive current and output current. The T-shaped equivalent circuit can accurately analyze the system energy field, and the quick identification of the parameters of the coupling loop element in the resonance compensation circuit is based on the equivalent circuit.
In the mutual inductance equivalent circuit, a square wave voltage source is used for equivalently replacing the high-frequency inversion output in front of the resonance compensation circuit, the resonance coupling circuit part is equivalent according to a mutual inductance model, wherein Cp、Lp、Ls、CsRespectively a primary side series capacitor, a primary side inductor, a secondary side parallel capacitor and a secondary side inductor, M is the original secondary side mutual inductance, Rp、Rs、 R0Respectively is a primary coil equivalent resistance, a secondary coil equivalent resistance, an equivalent load resistance, Up、U0Respectively the output voltage of the inverter and the voltage across the load, Ip、IsAnd I0Primary side inductive current, secondary side inductive current and output current. The mutual inductance equivalent circuit can visually reflect the working principle and the working characteristics of the system, and the resonant frequency of the system is identified after the parameters of the coupling loop are identified in real timeAnd calculating the coupling coefficient and judging the over-coupling state based on the equivalent circuit diagram.
Referring to fig. 5, according to the established equivalent circuit diagram, the frequency control method of the maximum output power of the system mainly includes the following four steps.
Step 2: and establishing a parameter equation for the T-shaped equivalent circuit by applying kirchhoff voltage law, and converting the parameter equation into a five-element linear equation by a simplification and element conversion method. Substituting the 5 groups of data detected in the step 1 into an equation, and solving a key parameter of the coupling loop, namely R in a simultaneous equation setp、Rs、R0、Cp、Lp、Ls、 CsAnd M.
And step 3: according to the mutual inductance equivalent circuit of the resonance compensation loop, the equivalent impedance expression of the secondary side is as follows:
wherein, ω is the working angular frequency of the inverter.
The primary equivalent impedance expression is:
according to kirchhoff's voltage law, the mutual inductance equivalent circuit can be represented by the following phasor equation:
phasor of equivalent circuit by the above mutual inductanceThe equation can define ZrIs a reflected impedance of the secondary side refracted to the primary side, where ZrComprises the following steps:
the equivalent input impedance of the primary side obtained by the method is
In practice, due to the internal resistance R of the receiving coils＜＜R0、Rs＜＜ωLsWith little effect on the output power of the system, R will be ignored in the following analysissFor the same reason, R can be ignoredp. The secondary equivalent impedance expression can be simplified as follows:
Zs＝R2+j(ωLs-X2)
wherein,
the equivalent input impedance of the primary side can be solved by the expressions of the equivalent impedance of the primary side, the equivalent impedance of the secondary side and the equivalent input impedance of the primary side
Zin＝Rin+jXin
Wherein
RinIs the real part, X, of the equivalent input impedance of the primary sideinIs the imaginary part of the equivalent input impedance of the primary side, omega is the resonance frequency, M is the primary and secondary mutual inductance, LpIs primary side inductance current, LsIs a secondary side inductor current, LpIs primary side inductive current, CpIs a secondary side inductor, R2Is the real part of the equivalent impedance of the secondary side,
is the imaginary part of the equivalent impedance of the secondary side except the inductance, and j is the imaginary unit.
When the resonance circuit resonates, the input impedance is purely resistive, that is, the imaginary part of the input impedance is zero. According to this condition, let Im(Zin)＝XinSubstituting the key parameters obtained in the step 2 to obtain a high-order equation related to the system resonance frequency omega, solving the equation to obtain at most 3 positive roots which are respectively the inherent resonance frequency omega0And two splitting frequencies omega1And ω2。
And 4, step 4: and (4) calculating the number m of the obtained solutions according to the high-order equation of the resonant frequency omega in the step (3), and judging whether the wireless power transmission system is in an over-coupling state. If m is 1, the root is the natural resonant frequency ω0I.e. the optimum operating frequency of the system. If m>And 1, calculating and comparing the system output power under each splitting frequency, and selecting the splitting frequency with the maximum output power as the optimal working frequency of the system. And finally, generating a PWM (pulse-width modulation) driving signal with the same optimal working frequency according to the determined optimal working frequency, and controlling the switching frequency of a primary side high-frequency inverter circuit of the system.
The control method provided by the invention simplifies the control circuit, and the control algorithm is used for rapidly identifying the key parameters of the coupling loop element of the wireless power transmission system only by detecting the output voltage and the output current, so as to determine the optimal working frequency of the system at the moment. In addition, the control method also considers the change of the coupling state of the system, and selects the splitting frequency in the inductive area as the optimal working frequency of the system aiming at the frequency splitting phenomenon in the over-coupling state, thereby keeping the maximization of the output power of the system.
Based on the same inventive concept, an embodiment of the present invention further provides a control device of a mobile wireless power transmission system, referring to fig. 6, where the control device includes:
the system equivalent circuit 610 is an equivalent circuit of the mobile wireless power transmission system, and the system equivalent circuit 610 includes a power frequency rectification circuit 611, a high-frequency inverter circuit 612, a resonance compensation circuit 613 and a frequency control circuit 614;
the detection circuit 620 is configured to collect multiple groups of output voltages and output currents of the mobile wireless power transmission system, where each of the output voltages and the output currents corresponds to an input high-frequency harmonic signal;
and a data processing circuit 630, electrically connected to the detection circuit 620, configured to determine, in the equivalent circuit, an optimal operating frequency of the mobile wireless power transmission system according to a plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each of the high-frequency harmonic signals, and provide the optimal operating frequency to the frequency control circuit 614, so that the frequency control circuit 614 generates a driving signal for controlling a switching frequency of the high-frequency inverter circuit 612 according to the optimal operating frequency, where a frequency of the driving signal is equal to the optimal operating frequency.
In one embodiment, the data processing circuit 630 comprises:
a modeling unit 631 for constructing a T-type equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit 613;
a first calculating unit 632, electrically connected to the modeling unit 631 and the detecting circuit 620, respectively, for determining key parameters of the T-shaped equivalent circuit according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
the second calculating unit 633, which is electrically connected to the modeling unit 631 and the first calculating unit 632, respectively, and is configured to determine a primary equivalent impedance, a secondary equivalent impedance, and a phasor equation of the mutual inductance equivalent circuit, determine a high-order equation related to a resonant frequency of the mobile wireless power transmission system according to a key parameter of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation, and solve to obtain at least one resonant frequency;
a determining unit 634, electrically connected to the two calculating units, configured to determine whether the mobile wireless power transmission system is in an over-coupling state according to at least one obtained resonant frequency, if so, using a split frequency in the resonant frequency that enables the mobile wireless power transmission system to have the maximum output power as the optimal operating frequency, otherwise, using a natural resonant frequency of the mobile wireless power transmission system with the resonant frequency as the optimal operating frequency.
In one embodiment, when the mobile wireless power transmission system is in a normal working state, one of the resonant frequencies is obtained according to a high-order equation of the resonant frequency, and is an inherent resonant frequency of the mobile wireless power transmission system; when the mobile wireless power transmission system is in an over-coupling state, two or three resonant frequencies are obtained according to a high-order equation of the resonant frequencies, wherein the natural resonant frequency of one mobile wireless power transmission system is the splitting frequency of the other mobile wireless power transmission system. Therefore, the number m of the solutions obtained by calculation according to the high-order equation of the resonant frequency omega can be used for judging whether the wireless power transmission system is in an over-coupling state. And when m is 1, the root is the natural resonant frequency ω0I.e. the optimum operating frequency of the system. And, when m>And 1, calculating and comparing the system output power under each splitting frequency, and selecting the splitting frequency with the maximum output power as the optimal working frequency of the system. And finally, generating a PWM (pulse-width modulation) driving signal with the same optimal working frequency according to the determined optimal working frequency, and controlling the switching frequency of the primary side high-frequency inverter circuit 612 of the system.
In one embodiment, the second calculating unit 633 for determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameter of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation is specifically configured to:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
Specifically, according to the mutual inductance equivalent circuit of the resonance compensation loop, the equivalent impedance expression of the secondary side is as follows:
wherein, ω is the working angular frequency of the inverter.
The primary equivalent impedance expression is:
according to kirchhoff's voltage law, the mutual inductance equivalent circuit can be represented by the following phasor equation:
z can be defined by the phasor equation of the mutual inductance equivalent circuitrIs a reflected impedance of the secondary side refracted to the primary side, where ZrComprises the following steps:
the equivalent input impedance of the primary side obtained by the method is
In practice, due to the internal resistance R of the receiving coils＜＜R0、Rs＜＜ωLsWith little effect on the output power of the system, R will be ignored in the following analysissFor the same reason, R can be ignoredp. The secondary equivalent impedance expression can be simplified as follows:
Zs＝R2+j(ωLs-X2)
wherein,
the equivalent input impedance of the primary side can be solved by the expressions of the equivalent impedance of the primary side, the equivalent impedance of the secondary side and the equivalent input impedance of the primary side
Zin＝Rin+jXin
Wherein
RinIs the real part, X, of the equivalent input impedance of the primary sideinIs the imaginary part of the equivalent input impedance of the primary side, omega is the resonance frequency, M is the primary and secondary mutual inductance, LpIs primary side inductance current, LsIs a secondary side inductor current, LpIs primary side inductive current, CpIs a secondary side inductor, R2Is the real part of the equivalent impedance of the secondary side,
is the imaginary part of the equivalent impedance of the secondary side except the inductance, and j is the imaginary unit.
When the resonance circuit resonates, the input impedance is purely resistive, that is, the imaginary part of the input impedance is zero. According to this condition, let Im(Zin)＝XinAnd (5) substituting the obtained key parameters in the step 2 to obtain a high-order equation related to the system resonance frequency omega.
To sum up, the embodiment of the invention provides a control method and a control device for a mobile wireless power transmission system. The control method comprises the following steps: constructing a system equivalent circuit 610 of the mobile wireless power transmission system, wherein the system equivalent circuit 610 comprises a power frequency rectifying circuit 611, a high-frequency inverter circuit 612, a resonance compensation circuit 613 and a frequency control circuit 614; sequentially inputting a plurality of high-frequency harmonic signals to a system equivalent circuit 610 of the mobile wireless power transmission system, and collecting output voltage and output current of the system equivalent circuit 610, wherein the frequencies of the high-frequency harmonic signals are different; in the system equivalent circuit 610, an optimal operating frequency of the mobile wireless power transmission system is determined according to the plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal. In the invention, the parameters of the coupling loop element in the system equivalent circuit of the wireless power transmission system are quickly identified by using a control algorithm only through the detection of the output voltage and the output current, and the optimal working frequency of the system at the moment is determined.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (13)
1. A method for controlling a mobile wireless power transmission system, comprising:
constructing a system equivalent circuit of the mobile wireless power transmission system, wherein the system equivalent circuit comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit;
sequentially inputting a plurality of high-frequency harmonic signals to a system equivalent circuit of the mobile wireless electric energy transmission system, and collecting output voltage and output current of the system equivalent circuit, wherein the frequencies of the high-frequency harmonic signals are different;
in the system equivalent circuit, calculating key parameters of a T-shaped equivalent circuit in the resonance compensation circuit according to the high-frequency harmonic signals, the output voltage and the output current corresponding to each high-frequency harmonic signal, so as to determine the optimal working frequency of the mobile wireless power transmission system.
2. The method of claim 1, wherein the determining an optimal operating frequency of the mobile wireless power transmission system according to a plurality of the high frequency harmonic signals and the output voltage and the output current corresponding to each of the high frequency harmonic signals in the equivalent circuit comprises:
constructing a T-shaped equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit;
determining key parameters of the T-shaped equivalent circuit according to the high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
determining the primary equivalent impedance, the secondary equivalent impedance and the phasor equation of the mutual inductance equivalent circuit;
determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency;
judging whether the mobile wireless power transmission system is in an over-coupling state or not according to the obtained at least one resonant frequency;
if so, taking the split frequency in the resonant frequency which enables the mobile wireless power transmission system to have the maximum output power as the optimal working frequency;
otherwise, the natural resonant frequency of the mobile wireless power transmission system is taken as the optimal working frequency.
3. The method as claimed in claim 2, wherein said determining whether the mobile wireless power transmission system is in an over-coupled state according to the obtained at least one resonant frequency comprises:
judging whether the number of the resonance frequencies obtained by solving is greater than 1;
if so, judging that the mobile wireless electric energy transmission system is in an over-coupling state;
otherwise, the mobile wireless electric energy transmission system is judged to be in a normal working state.
4. The control method according to claim 3, wherein the setting, as the optimal operating frequency, a split frequency among the resonance frequencies at which the mobile wireless power transmission system has a maximum output power includes:
calculating the output power of the mobile wireless power transmission system working at each split frequency;
comparing the output powers, and determining the maximum output power and the splitting frequency corresponding to the maximum output power;
and taking the splitting frequency corresponding to the large output power as the optimal working frequency.
5. The control method according to claim 2, wherein the determining a high-order equation about the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation comprises:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
6. The control method of claim 2, wherein a primary side equivalent input impedance of the mutual inductance equivalent circuit
Zin＝Rin+jXin
Wherein
RinIs the real part, X, of the equivalent input impedance of the primary sideinIs the imaginary part of the equivalent input impedance of the primary side, omega is the resonance frequency, M is the primary and secondary mutual inductance, LpIs a primary side inductance, LsIs a secondary inductor, CpCompensating the capacitance for the primary side, CsCompensating the capacitance for the secondary side, R2Is the real part of the equivalent impedance of the secondary side,
is the imaginary part of the equivalent impedance of the secondary side except the inductance, and j is the imaginary unit.
7. The control method according to claim 1, further comprising:
and generating a driving signal for controlling the switching frequency of the high-frequency inverter circuit according to the optimal working frequency, wherein the frequency of the driving signal is equal to the optimal working frequency.
8. The control method of claim 2, wherein the mobile wireless power transmission system is provided with 5 high frequency harmonic signals in sequence.
9. The method of claim 8, wherein said determining key parameters of said T-shaped equivalent circuit based on a plurality of said high frequency harmonic signals and said output voltage and said output current for each of said high frequency harmonic signals comprises:
establishing a quinary linear equation for the T-shaped equivalent circuit of the resonance compensation circuit by utilizing kirchhoff voltage law;
and substituting each high-frequency harmonic signal, the output voltage and the output current corresponding to each high-frequency harmonic signal into the quintuple equation, and calculating to obtain the key parameters of the T-shaped equivalent circuit.
10. A control apparatus for a mobile wireless power transmission system, comprising:
the system equivalent circuit is an equivalent circuit of the mobile wireless electric energy transmission system and comprises a power frequency rectifying circuit, a high-frequency inverter circuit, a resonance compensation circuit and a frequency control circuit;
the detection circuit is used for acquiring a plurality of groups of output voltages and output currents of the mobile wireless power transmission system, and each output voltage and each output current corresponds to an input high-frequency harmonic signal;
and the data processing circuit is electrically connected with the detection circuit and used for calculating key parameters of a T-shaped equivalent circuit in the resonance compensation circuit in the equivalent circuit according to a plurality of high-frequency harmonic signals, the output voltage and the output current corresponding to each high-frequency harmonic signal, so as to determine the optimal working frequency of the mobile wireless power transmission system and provide the optimal working frequency to the frequency control circuit, so that the frequency control circuit generates a driving signal for controlling the switching frequency of the high-frequency inverter circuit according to the optimal working frequency, wherein the frequency of the driving signal is equal to the optimal working frequency.
11. The control device of claim 10, wherein the data processing circuit comprises:
the modeling unit is used for constructing a T-shaped equivalent circuit and a mutual inductance equivalent circuit of the resonance compensation circuit;
the first calculation unit is electrically connected with the modeling unit and the detection circuit respectively and used for determining key parameters of the T-shaped equivalent circuit according to a plurality of high-frequency harmonic signals and the output voltage and the output current corresponding to each high-frequency harmonic signal;
the second calculation unit is electrically connected with the modeling unit and the first calculation unit respectively and is used for determining a primary equivalent impedance, a secondary equivalent impedance and a phasor equation of the mutual inductance equivalent circuit, determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to key parameters of the T-shaped equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance and the phasor equation, and solving to obtain at least one resonant frequency;
and the judging unit is electrically connected with the two calculating units and is used for judging whether the mobile wireless power transmission system is in an over-coupling state or not according to the obtained at least one resonant frequency, if so, the splitting frequency in the resonant frequency enabling the mobile wireless power transmission system to have the maximum output power is taken as the optimal working frequency, and otherwise, the inherent resonant frequency of the mobile wireless power transmission system is taken as the optimal working frequency.
12. The control device of claim 11,
when the mobile wireless power transmission system is in a normal working state, obtaining one resonant frequency according to a high-order equation of the resonant frequency, wherein the resonant frequency is the inherent resonant frequency of the mobile wireless power transmission system;
when the mobile wireless power transmission system is in an over-coupling state, two or three resonant frequencies are obtained according to a high-order equation of the resonant frequencies, wherein the natural resonant frequency of one mobile wireless power transmission system is the splitting frequency of the other mobile wireless power transmission system.
13. The control device according to claim 11, wherein the second calculating unit is configured to determine a higher-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-type equivalent circuit, the primary equivalent impedance, the secondary equivalent impedance, and the phasor equation, and is specifically configured to:
determining a primary equivalent input impedance of the mutual inductance equivalent circuit according to the primary equivalent impedance, the secondary equivalent impedance and the phasor equation;
and determining a high-order equation related to the resonant frequency of the mobile wireless power transmission system according to the key parameters of the T-shaped equivalent circuit and the primary equivalent input impedance of the mutual inductance equivalent circuit.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911337896.1A CN111082541B (en) | 2019-12-23 | 2019-12-23 | Control method and device of mobile wireless power transmission system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911337896.1A CN111082541B (en) | 2019-12-23 | 2019-12-23 | Control method and device of mobile wireless power transmission system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111082541A CN111082541A (en) | 2020-04-28 |
| CN111082541B true CN111082541B (en) | 2021-08-20 |
Family
ID=70316700
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201911337896.1A Active CN111082541B (en) | 2019-12-23 | 2019-12-23 | Control method and device of mobile wireless power transmission system |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN111082541B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN113300484A (en) * | 2021-05-14 | 2021-08-24 | 鲁东大学 | Method for inhibiting power frequency ripple of wireless power supply system through phase modulation |
| CN113300483A (en) * | 2021-05-14 | 2021-08-24 | 鲁东大学 | Method for inhibiting power frequency ripple of wireless power supply system through frequency modulation |
| CN113300485A (en) * | 2021-05-14 | 2021-08-24 | 鲁东大学 | Method for inhibiting power frequency ripple of wireless power supply system through duty ratio modulation |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104009555A (en) * | 2014-06-16 | 2014-08-27 | 南京矽力杰半导体技术有限公司 | Resonant type non-contact power unit, electricity transmitter and non-contact power supply method |
| CN106787247A (en) * | 2017-01-13 | 2017-05-31 | 北京空间飞行器总体设计部 | A kind of wireless energy transmission efficiency test system |
| CN106953423A (en) * | 2017-04-26 | 2017-07-14 | 重庆大学 | Parameter Design Method of Bilateral LC Compensated ECPT System with Constant Voltage Output Characteristic |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3719510B2 (en) * | 2002-04-08 | 2005-11-24 | アルプス電気株式会社 | Storage room with contactless charger |
| CN106100345B (en) * | 2016-07-07 | 2019-05-24 | 上海交通大学 | Bilateral T-S compensation topology and characteristic parameter matching method for wireless power transmission |
| CN106787243B (en) * | 2016-12-23 | 2019-08-02 | 中国人民解放军海军工程大学 | A kind of LCCL resonance structure of fundamental current compensation higher harmonic current |
| CN108964289B (en) * | 2018-07-23 | 2020-03-31 | 重庆大学 | ECPT system with double-T resonant network and its parameter design method |
-
2019
- 2019-12-23 CN CN201911337896.1A patent/CN111082541B/en active Active
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104009555A (en) * | 2014-06-16 | 2014-08-27 | 南京矽力杰半导体技术有限公司 | Resonant type non-contact power unit, electricity transmitter and non-contact power supply method |
| CN106787247A (en) * | 2017-01-13 | 2017-05-31 | 北京空间飞行器总体设计部 | A kind of wireless energy transmission efficiency test system |
| CN106953423A (en) * | 2017-04-26 | 2017-07-14 | 重庆大学 | Parameter Design Method of Bilateral LC Compensated ECPT System with Constant Voltage Output Characteristic |
Non-Patent Citations (1)
| Title |
|---|
| 磁耦合谐振式无线电能传输新进展;赵争鸣,张艺明,陈凯楠;《中国电机工程学报》;20130125;第33卷(第3期);1-9页 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN111082541A (en) | 2020-04-28 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN111082541B (en) | Control method and device of mobile wireless power transmission system | |
| CN109302070A (en) | Circuit topology structure of power converter and its control method | |
| Liu et al. | Capacitive power transfer system with double T-type resonant network for mobile devices charging/supply | |
| Ivensky et al. | A comparison of piezoelectric transformer AC/DC converters with current doubler and voltage doubler rectifiers | |
| CN106899212B (en) | ECPT system of symmetrical LCC resonant network and its parameter design method | |
| CN103609013A (en) | Method and apparatus for controlling LCL converters using asymmetric voltage cancellation techniques | |
| CN108920808A (en) | The LC of piezoelectric ultrasonic transducer matches modeling method | |
| CN108988506B (en) | PT symmetrical wireless power transmission circuit and construction method thereof | |
| Wang et al. | A simple approach for load identification in current-fed inductive power transfer system | |
| CN105743228B (en) | A kind of radio energy transmission system resonance compensation method of any constant voltage output | |
| Cochran et al. | Modeling a 6.78 mhz synchronous wpt rectifier with reduced thd | |
| CN111200297B (en) | Amplitude and phase corrector selection method and system for improving impedance characteristics of flexible straight systems | |
| Suarez et al. | Frequency splitting in an LCLC capacitive wireless power transfer system for electric vehicle charging | |
| Petersen et al. | Load dependent power control in series-series compensated electric vehicle inductive power transfer systems | |
| Nam et al. | Optimal design method for series LCLC resonant converter based on analytical solutions for voltage gain resonant peaks | |
| CN113193663A (en) | Load and mutual inductance dual-parameter identification method for magnetic coupling wireless power transmission system | |
| CN112532198A (en) | Radio frequency ion source impedance matching method and device | |
| Zan et al. | Inductive wireless power transfer at 100MHz with wide load range and constant output current | |
| CN117674445A (en) | Frequency sweep optimization method for output power of underwater WPT system considering eddy current loss | |
| CN108539874B (en) | Wireless charging adaptive impedance matching system and method | |
| CN107257198A (en) | The adjusting method and circuit of a kind of power-efficient | |
| CN115173579B (en) | An automatic tuning method based on current and voltage detection at the transmitting end | |
| CN107634657B (en) | Predictive control method and device for matrix converter | |
| CN116566073A (en) | Self-excitation frequency control method and system of string compensation type WPT system | |
| Liu et al. | A passive fractional-order capacitor to realize zero angle phase input for wireless transfer system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |