CN112583285A - Method and system for determining equivalent load impedance of rectifying circuit of wireless charging system - Google Patents

Method and system for determining equivalent load impedance of rectifying circuit of wireless charging system Download PDF

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CN112583285A
CN112583285A CN202011357027.8A CN202011357027A CN112583285A CN 112583285 A CN112583285 A CN 112583285A CN 202011357027 A CN202011357027 A CN 202011357027A CN 112583285 A CN112583285 A CN 112583285A
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full
wireless charging
charging system
bridge
rectification circuit
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郭彦杰
李芳�
王丽芳
张玉旺
陶成轩
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Institute of Electrical Engineering of CAS
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Institute of Electrical Engineering of CAS
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/02—Conversion of ac power input into dc power output without possibility of reversal
    • H02M7/04—Conversion of ac power input into dc power output without possibility of reversal by static converters
    • H02M7/12—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/21—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/217—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M7/219—Conversion of ac power input into dc power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only in a bridge configuration
    • 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
    • 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
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
    • H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
    • H02J7/04—Regulation of charging current or voltage
    • H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices

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  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention relates to a method and a system for determining equivalent load impedance of a rectifying circuit of a wireless charging system. The method comprises the following steps: determining a relation model between the input current of a full-bridge rectification circuit and an angle variable of the wireless charging system based on the working angular frequency of the wireless charging system and the input inductance of the full-bridge rectification circuit; obtaining a fundamental wave Fourier coefficient of input current of the full-bridge rectification circuit through Fourier transform based on the relation model; determining the fundamental wave amplitude and the tangent value of a fundamental wave phase angle of input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient; determining the equivalent load impedance of the full-bridge rectification circuit of the wireless charging system based on the fundamental wave amplitude value and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit and the load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion. The invention can reduce the calculation amount and is simultaneously suitable for a wireless charging system of a battery type load and a wireless charging system of a resistance type load.

Description

Method and system for determining equivalent load impedance of rectifying circuit of wireless charging system
Technical Field
The invention relates to the technical field of wireless charging, in particular to a method and a system for determining equivalent load impedance of a rectifying circuit of a wireless charging system.
Background
The wireless charging system has the advantages of no physical connection, less wear and aging, convenience in use and the like, and is widely applied to the fields of electric automobiles, mobile phones, smart homes and the like in recent years. Because of its simple structure, low cost and easy implementation, a full-bridge rectifier circuit is often used in a wireless charging system to convert high-frequency ac power into dc power for charging a battery. Patent CN 108173299 a "wireless power receiving device, and wireless power transmitting device and rectifier using the same" discloses a wireless charging device involving a full-bridge rectifier circuit, but does not relate to a method for calculating an equivalent load impedance of the full-bridge rectifier circuit. Patent CN 109217493 a, "input impedance calculation method for discontinuous operation mode of rectifier bridge of wireless charging system", discloses a method for calculating input impedance of rectifier bridge of wireless charging system, but is not suitable for continuous mode and includes complex calculation process. Patent CN 107979298B, "a method for calculating equivalent impedance of a rectifier bridge load of a wireless charging system", discloses a method for calculating equivalent impedance of a rectifier bridge load of a wireless charging system, but needs to solve complex calculation processes such as full response of a state space equation, and is only applicable to a wireless charging system with a resistance type load.
Therefore, how to provide a method for determining the equivalent load impedance of the full-bridge rectifier circuit, which is simple and feasible and is simultaneously suitable for the wireless charging system with the battery type and the resistor type loads, becomes a technical problem to be solved urgently.
Disclosure of Invention
The invention aims to provide a method and a system for determining equivalent load impedance of a rectifying circuit of a wireless charging system, which are used for reducing the calculation amount and are simultaneously suitable for a wireless charging system with a battery type load and a wireless charging system with a resistance type load.
In order to achieve the purpose, the invention provides the following scheme:
a method of determining a wireless charging system rectifier circuit equivalent load impedance, comprising:
determining a relation model between the input current of a full-bridge rectification circuit and an angle variable of a wireless charging system based on the working angular frequency of the wireless charging system and the input inductance of the full-bridge rectification circuit;
obtaining a fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit through Fourier transformation based on a relation model between the input current of the full-bridge rectification circuit of the wireless charging system and an angle variable;
determining the fundamental wave amplitude and the tangent value of a fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
determining an equivalent load impedance of a full-bridge rectification circuit of the wireless charging system based on a fundamental wave amplitude value and a tangent value of a fundamental wave phase angle of input current of the full-bridge rectification circuit and a load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion.
Optionally, a relationship model between the input current of the full-bridge rectification circuit and the angle variable of the wireless charging system is as follows:
Figure BDA0002802897560000021
wherein irec+The full-bridge rectifier circuit inputs current for a positive half cycle and a negative half cycle; i.e. irec-The input current of the full-bridge rectifying circuit is a negative half cycle; vc2pInputting the front end voltage of an inductor for a full-bridge rectifying circuit; theta is an angle variable; thetarThe phase difference between the front end voltage of an input inductor and the input current of the full-bridge rectifying circuit is obtained; u shapebLoading a voltage for the wireless charging system; omega is the working angular frequency of the wireless charging system; full-bridge rectifier circuit input inductor front end voltage, phase difference between full-bridge rectifier circuit input inductor front end voltage and input current and wireless charging system loadThe voltage satisfies the relation 2Vc2pcosθr＝πUb(ii) a The relation among the charging current of the wireless charging system, the front end voltage of the input inductor of the full-bridge rectification circuit, the phase difference between the front end voltage of the input inductor of the full-bridge rectification circuit and the input current and the input inductor of the full-bridge rectification circuit is satisfied
Figure BDA0002802897560000022
In the formula, LsAn inductor is input into the full-bridge rectifying circuit; i isbAnd charging current for the wireless charging system.
Optionally, based on a relation model between the input current of the full-bridge rectifier circuit of the wireless charging system and the angle variable, a fundamental fourier coefficient of the input current of the full-bridge rectifier circuit is obtained through fourier transform, and the method specifically includes:
using formulas
Figure BDA0002802897560000031
Performing Fourier transform to obtain a fundamental Fourier coefficient of input current of the full-bridge rectification circuit; wherein, a1And b1The fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit; i.e. irec+The full-bridge rectifier circuit inputs current for a positive half cycle and a negative half cycle; i.e. irec-The input current of the full-bridge rectifying circuit is a negative half cycle; theta is an angle variable.
Optionally, the fundamental fourier coefficient of the input current of the full-bridge rectifier circuit is:
Figure BDA0002802897560000032
wherein L issAn inductor is input into the full-bridge rectifying circuit; u shapebLoading a voltage for the wireless charging system; i isbCharging current for the wireless charging system; omega is wireless charging system operating angular frequency.
Optionally, the determining, according to the fundamental fourier coefficient of the input current of the full-bridge rectifier circuit, the fundamental amplitude and the tangent of the fundamental phase angle of the input current of the full-bridge rectifier circuit includes:
using formulas
Figure BDA0002802897560000033
Determining the fundamental wave amplitude of the input current of the full-bridge rectification circuit to obtain the fundamental wave amplitude of the input current of the full-bridge rectification circuit; wherein, | AiI is the fundamental wave amplitude of the input current of the full-bridge rectification circuit; a is1And b1The fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
using formulas
Figure BDA0002802897560000034
Determining the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit to obtain the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit; wherein, thetaiThe fundamental wave phase angle of the input current of the full-bridge rectification circuit is obtained.
Optionally, the fundamental amplitude of the input current of the full-bridge rectifier circuit is:
Figure BDA0002802897560000035
wherein, UbLoading a voltage for the wireless charging system; i isbCharging current for the wireless charging system; omega is the working angular frequency of the wireless charging system; l issAn inductor is input into the full-bridge rectifying circuit;
the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit is as follows:
Figure BDA0002802897560000041
optionally, the determining, based on the fundamental amplitude and the tangent of the fundamental phase angle of the input current of the full-bridge rectifier circuit and the load voltage of the wireless charging system, the equivalent load impedance of the full-bridge rectifier circuit of the wireless charging system includes:
determining the sine value and the cosine value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit;
determining the fundamental wave amplitude and the fundamental wave phase angle of the input voltage of the full-bridge rectification circuit based on the load voltage of the wireless charging system;
using formulas
Figure BDA0002802897560000042
Determining an equivalent load impedance of a full-bridge rectification circuit of the wireless charging system; wherein R iseA resistance part of equivalent load impedance of a full-bridge rectifying circuit of the wireless charging system; l iseAn inductance part of equivalent load impedance of a full bridge rectification circuit of the wireless charging system; | AuI is the fundamental wave amplitude of the input voltage of the full-bridge rectification circuit; thetauThe fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; | AiI is the fundamental wave amplitude of the input current of the full-bridge rectification circuit; thetaiThe fundamental wave phase angle of the current is input into the full-bridge rectification circuit; omega is wireless charging system operating angular frequency.
Optionally, the determining, based on the load voltage of the wireless charging system, a fundamental amplitude and a fundamental phase angle of the input voltage of the full-bridge rectifier circuit specifically includes:
using formulas
Figure BDA0002802897560000043
Determining the fundamental wave amplitude and the fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; wherein, | AuI is the fundamental wave amplitude of the input voltage of the full-bridge rectification circuit; thetauThe fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; u shapebLoading the wireless charging system with a voltage.
Optionally, when the load in the wireless charging system is a battery-type load, the equivalent load impedance of the full-bridge rectifier circuit of the wireless charging system is:
Figure BDA0002802897560000051
wherein L issFor the input inductance, U, of a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for the wireless charging system;
when the load in the wireless charging system is a resistance type load, the equivalent load impedance of the full-bridge rectifying circuit of the wireless charging system is as follows:
Figure BDA0002802897560000052
wherein R isLIs the load resistance value of the wireless charging system.
The invention also provides a system for determining equivalent load impedance of a rectifying circuit of a wireless charging system, which comprises the following steps:
the wireless charging system comprises a relation model determining module, a relation model calculating module and a relation model calculating module, wherein the relation model determining module is used for determining a relation model between the input current of the full-bridge rectifying circuit and an angle variable of the wireless charging system based on the working angle frequency of the wireless charging system and the input inductance of the full-bridge rectifying circuit;
the fundamental wave Fourier coefficient determining module of the input current of the full-bridge rectification circuit is used for obtaining the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit through Fourier transform based on a relation model between the input current of the full-bridge rectification circuit and an angle variable of the wireless charging system;
the device comprises a module for determining the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit, a module for determining the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
the equivalent load impedance determination module of the full-bridge rectification circuit is used for determining the equivalent load impedance of the full-bridge rectification circuit of the wireless charging system based on the fundamental wave amplitude value and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit and the load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the invention does not need complex calculation process, the calculation method is simple, and the calculation amount is small; and can be applied to both a wireless charging system of a battery type load and a wireless charging system of a resistance type load.
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In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart illustrating a method for determining an equivalent load impedance of a rectifier circuit of a wireless charging system according to the present invention;
fig. 2 is a circuit diagram of a wireless charging system for a battery-type load;
FIG. 3 is a circuit diagram of a wireless charging system for a resistive load;
fig. 4 is a schematic structural diagram of a system for determining equivalent load impedance of a rectifying circuit of a wireless charging system according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a method for determining equivalent load impedance of a rectifying circuit of a wireless charging system according to the present invention. As shown in fig. 1, the method for determining the equivalent load impedance of the rectifying circuit of the wireless charging system of the invention comprises the following steps:
step 100: based on the working angular frequency of the wireless charging system and the input inductance of the full-bridge rectification circuit, a relation model between the input current of the full-bridge rectification circuit and an angle variable of the wireless charging system is determined.
The relation model between the input current of the full-bridge rectification circuit and the angle variable of the wireless charging system is as follows:
Figure BDA0002802897560000071
wherein irec+The full-bridge rectifier circuit inputs current for a positive half cycle and a negative half cycle; i.e. irec-The input current of the full-bridge rectifying circuit is a negative half cycle; vc2pInputting the front end voltage of an inductor for a full-bridge rectifying circuit; theta is an angle variable; thetarThe phase difference between the front end voltage of an input inductor and the input current of the full-bridge rectifying circuit is obtained; u shapebLoading a voltage for the wireless charging system; omega is the working angular frequency of the wireless charging system and is a known parameter of the wireless charging system; the relation 2V is satisfied between the front end voltage of the input inductor of the full-bridge rectification circuit, the phase difference between the front end voltage of the input inductor of the full-bridge rectification circuit and the input current and the load voltage of the wireless charging systemc2pcosθr＝πUb(ii) a The relation among the charging current of the wireless charging system, the front end voltage of the input inductor of the full-bridge rectification circuit, the phase difference between the front end voltage of the input inductor of the full-bridge rectification circuit and the input current and the input inductor of the full-bridge rectification circuit is satisfied
Figure BDA0002802897560000072
In the formula, LsThe inductance is input into the full-bridge rectification circuit and is obtained by measuring in advance; i isbAnd charging current for the wireless charging system.
Step 200: based on a relation model between the input current of the full-bridge rectification circuit of the wireless charging system and an angle variable, a fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit is obtained through Fourier transformation.
Calculating input current i of positive half period and negative half period of full-bridge rectification circuit by formula (1)rec+And irec-The time domain expression of (3) is obtained by integrating θ into the angle variable through fourier transform, and the fundamental fourier coefficient of the input current of the full bridge rectifier circuit shown in formula (2) is obtained:
Figure BDA0002802897560000073
wherein, a1And b1Fundamental Fourier coefficient i of input current of full-bridge rectification circuitrec+And irec-The input current of the full-bridge rectification circuit is respectively a positive half cycle and a negative half cycle, theta is an angle variable, and LsFor the input inductance, U, of a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for the wireless charging system, wherein omega is the working angular frequency of the wireless charging system.
Step 300: and determining the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit.
Calculating the fundamental wave amplitude and the tangent value of a phase angle of the input current of the full-bridge rectification circuit by a formula (3):
Figure BDA0002802897560000081
wherein, | AiI is the fundamental wave amplitude of the input current of the full-bridge rectification circuit, thetaiFundamental phase angle a of input current to full-bridge rectifier circuit1And b1Fundamental Fourier coefficient, L, of input current to full-bridge rectifier circuitsFor the input inductance, U, of a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for the wireless charging system, wherein omega is the working angular frequency of the wireless charging system.
Step 400: and determining the equivalent load impedance of the full-bridge rectifying circuit of the wireless charging system based on the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectifying circuit and the load voltage of the wireless charging system. The equivalent load impedance includes a resistive portion and an inductive portion. The specific process is as follows:
firstly, calculating the sine value and the cosine value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit by a formula (4):
Figure BDA0002802897560000082
wherein, thetaiFundamental phase angle, L, of input current to full-bridge rectifier circuitsFor the input inductance, U, of a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for the wireless charging system, wherein omega is the working angular frequency of the wireless charging system.
Then, the fundamental amplitude and phase angle value of the input voltage of the full-bridge rectifier circuit are calculated by the formula (5):
Figure BDA0002802897560000083
wherein, | AuI is the fundamental amplitude of the input voltage of the full-bridge rectification circuit, thetauFundamental phase angle, U, of input voltage to full-bridge rectifier circuitbLoading the wireless charging system with a voltage.
And finally, calculating to obtain the equivalent load impedance of the full-bridge rectifying circuit of the wireless charging system through a formula (6):
Figure BDA0002802897560000091
wherein R iseAnd LeThe impedance part and the inductance part are respectively equivalent load impedance of the full-bridge rectifying circuit of the wireless charging system.
The present invention can be applied to a wireless charging system for a battery type load and a wireless charging system for a resistance type load.
FIG. 2 is a circuit diagram of a wireless charging system for a battery-type load, as shown in FIG. 2, where U is showndAs a power supply, CinFor inputting filter capacitors, switching tubes G1-G4Make up of an inverter, LpFor the inverter output inductance, C1sAnd C1pIs a primary side compensation capacitor, L1Is a primary coil, L2Is a secondary coil, C2sAnd C2pCompensating the capacitance for the secondary side, LsAn inductor and a power diode D are input into the full-bridge rectification circuit1-D4Form a full bridge rectifier circuit, CoTo output filter capacitance, LoTo output the filter inductance, irecFor the input current of a full-bridge rectifier circuit, urecFor the input voltage of a full-bridge rectifier circuit, Vc2pInput of the inductor front-end voltage, U, for a full-bridge rectifier circuitbRepresenting the battery voltage, i.e. the load voltage of the wireless charging system, IbRepresenting the battery charging current, i.e., the wireless charging system charging current. Input filter capacitor CinInput terminal and power supply UdConnected to an input filter capacitor CinAnd inverter G1-G4Is connected to the input terminal of an inverter G1-G4Output terminal of and inverter output inductor LpIs connected with the input end of the inverter output inductor LpOutput end and primary side compensation capacitor C1sAnd C1pIs connected to the primary side compensation capacitor C1sAnd C1pOutput end of and primary side coil L1Is connected to the primary winding L1Output end and secondary winding L of2Is connected to the secondary winding L2Output end and secondary side compensation capacitor C2sAnd C2pIs connected with a secondary side compensation capacitor C2sAnd C2pOutput end of the full-bridge rectification circuit and input inductor L of the full-bridge rectification circuitsIs connected with the input end of the full-bridge rectifying circuit, and the input inductor L of the full-bridge rectifying circuitsAnd a full-bridge rectification circuit D1-D4Is connected to the input terminal of a full-bridge rectifier circuit D1-D4Output terminal and output filter capacitor CoAnd an output filter inductor LoIs connected with the input end of the output filter capacitor CoAnd an output filter inductor LoIs connected to a wireless charging system load, i.e. a battery.
Based on the wireless charging system shown in fig. 2, the equivalent load impedance of the full-bridge rectification circuit of the wireless charging system with battery-type load is derived from equation (6):
Figure BDA0002802897560000101
FIG. 3 is a circuit diagram of a wireless charging system for a resistive load, as shown in FIG. 3, where U isdAs a power supply, CinFor inputting filter capacitors, switching tubes G1-G4Make up of an inverter, LpFor the inverter output inductance, C1sAnd C1pIs a primary side compensation capacitor, L1Is a primary coil, L2Is a secondary coil, C2sAnd C2pCompensating the capacitance for the secondary side, LsAn inductor and a power diode D are input into the full-bridge rectification circuit1-D4Form a full bridge rectifier circuit, CoTo output filter capacitance, LoTo output the filter inductance, irecFor the input current of a full-bridge rectifier circuit, urecFor the input voltage of a full-bridge rectifier circuit, Vc2pInput of the inductor front-end voltage, U, for a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for wireless charging system, RLIs the load resistance value of the wireless charging system. Input filter capacitor CinInput terminal and power supply UdConnected to an input filter capacitor CinAnd inverter G1-G4Is connected to the input terminal of an inverter G1-G4Output terminal of and inverter output inductor LpIs connected with the input end of the inverter output inductor LpOutput end and primary side compensation capacitor C1sAnd C1pIs connected to the primary side compensation capacitor C1sAnd C1pOutput end of and primary side coil L1Is connected to the primary winding L1Output end and secondary side ofCoil L2Is connected to the secondary winding L2Output end and secondary side compensation capacitor C2sAnd C2pIs connected with a secondary side compensation capacitor C2sAnd C2pOutput end of the full-bridge rectification circuit and input inductor L of the full-bridge rectification circuitsIs connected with the input end of the full-bridge rectifying circuit, and the input inductor L of the full-bridge rectifying circuitsAnd a full-bridge rectification circuit D1-D4Is connected to the input terminal of a full-bridge rectifier circuit D1-D4Output terminal and output filter capacitor CoAnd an output filter inductor LoIs connected with the input end of the output filter capacitor CoAnd an output filter inductor LoThe output terminal of (2) is connected with a load of the wireless charging system, namely a load resistor.
Based on the wireless charging system shown in fig. 3, the equivalent load impedance of the full-bridge rectification circuit of the wireless charging system with the resistive load is derived from equation (6):
Figure BDA0002802897560000111
wherein R isLLoad voltage U for load resistance value of wireless charging systembDivide by wireless charging system charging current and calculate IbThus obtaining the product.
Based on the method, the invention further provides a system for determining the equivalent load impedance of the rectifying circuit of the wireless charging system, and fig. 4 is a schematic structural diagram of the system for determining the equivalent load impedance of the rectifying circuit of the wireless charging system. As shown in fig. 4, the system for determining equivalent load impedance of a rectifying circuit of a wireless charging system of the present invention comprises:
the relation model determining module 401 is configured to determine a relation model between an input current and an angle variable of a full-bridge rectifier circuit of the wireless charging system based on a working angular frequency of the wireless charging system and an input inductance of the full-bridge rectifier circuit.
And a fundamental wave fourier coefficient determination module 402 of the input current of the full-bridge rectifier circuit, configured to obtain a fundamental wave fourier coefficient of the input current of the full-bridge rectifier circuit through fourier transform based on a relationship model between the input current of the full-bridge rectifier circuit and the angle variable of the wireless charging system.
The module 403 for determining the fundamental amplitude and the tangent of the fundamental phase angle of the input current of the full-bridge rectifier circuit is configured to determine the fundamental amplitude and the tangent of the fundamental phase angle of the input current of the full-bridge rectifier circuit according to the fundamental fourier coefficient of the input current of the full-bridge rectifier circuit.
An equivalent load impedance determination module 404 of the full-bridge rectification circuit, configured to determine an equivalent load impedance of the full-bridge rectification circuit of the wireless charging system based on a fundamental amplitude and a tangent value of a fundamental phase angle of an input current of the full-bridge rectification circuit and a load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.

Claims (10)

1. A method for determining equivalent load impedance of a rectifying circuit of a wireless charging system is characterized by comprising the following steps:
determining a relation model between the input current of a full-bridge rectification circuit and an angle variable of a wireless charging system based on the working angular frequency of the wireless charging system and the input inductance of the full-bridge rectification circuit;
obtaining a fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit through Fourier transformation based on a relation model between the input current of the full-bridge rectification circuit of the wireless charging system and an angle variable;
determining the fundamental wave amplitude and the tangent value of a fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
determining an equivalent load impedance of a full-bridge rectification circuit of the wireless charging system based on a fundamental wave amplitude value and a tangent value of a fundamental wave phase angle of input current of the full-bridge rectification circuit and a load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion.
2. The method for determining the equivalent load impedance of the rectifying circuit of the wireless charging system according to claim 1, wherein the relationship model between the input current of the full-bridge rectifying circuit of the wireless charging system and the angle variable is as follows:
Figure FDA0002802897550000011
wherein irec+The full-bridge rectifier circuit inputs current for a positive half cycle and a negative half cycle; i.e. irec-The input current of the full-bridge rectifying circuit is a negative half cycle; vc2pInputting the front end voltage of an inductor for a full-bridge rectifying circuit; theta is an angle variable; thetarThe phase difference between the front end voltage of an input inductor and the input current of the full-bridge rectifying circuit is obtained; u shapebLoading a voltage for the wireless charging system; omega is the working angular frequency of the wireless charging system; the relation 2V is satisfied between the front end voltage of the input inductor of the full-bridge rectification circuit, the phase difference between the front end voltage of the input inductor of the full-bridge rectification circuit and the input current and the load voltage of the wireless charging systemc2pcosθr＝πUb(ii) a Charging current of wireless charging system, full-bridge rectifier circuit input inductor front end voltage and input currentSatisfies the relation between the phase difference and the input inductance of the full-bridge rectification circuit
Figure FDA0002802897550000012
In the formula, LsAn inductor is input into the full-bridge rectifying circuit; i isbAnd charging current for the wireless charging system.
3. The method for determining the equivalent load impedance of the rectifying circuit of the wireless charging system according to claim 1, wherein the obtaining of the fundamental fourier coefficient of the input current of the full-bridge rectifying circuit through fourier transform based on the relationship model between the input current of the full-bridge rectifying circuit and the angle variable of the wireless charging system specifically comprises:
using formulas
Figure FDA0002802897550000021
Performing Fourier transform to obtain a fundamental Fourier coefficient of input current of the full-bridge rectification circuit; wherein, a1And b1The fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit; i.e. irec+The full-bridge rectifier circuit inputs current for a positive half cycle and a negative half cycle; i.e. irec-The input current of the full-bridge rectifying circuit is a negative half cycle; theta is an angle variable.
4. The method for determining the equivalent load impedance of the rectifier circuit of the wireless charging system according to claim 3, wherein the fundamental Fourier coefficient of the input current of the full-bridge rectifier circuit is as follows:
Figure FDA0002802897550000022
wherein L issAn inductor is input into the full-bridge rectifying circuit; u shapebLoading a voltage for the wireless charging system; i isbCharging current for the wireless charging system; omega is wireless charging system operating angular frequency.
5. The method for determining the equivalent load impedance of the rectifier circuit of the wireless charging system according to claim 1, wherein the determining the fundamental amplitude and the tangent of the fundamental phase angle of the input current of the full-bridge rectifier circuit according to the fundamental fourier coefficient of the input current of the full-bridge rectifier circuit specifically comprises:
using formulas
Figure FDA0002802897550000023
Determining the fundamental wave amplitude of the input current of the full-bridge rectification circuit to obtain the fundamental wave amplitude of the input current of the full-bridge rectification circuit; wherein, | AiI is the fundamental wave amplitude of the input current of the full-bridge rectification circuit; a is1And b1The fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
using formulas
Figure FDA0002802897550000024
Determining the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit to obtain the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit; wherein, thetaiThe fundamental wave phase angle of the input current of the full-bridge rectification circuit is obtained.
6. The method for determining the equivalent load impedance of the rectifier circuit of the wireless charging system according to claim 5, wherein the fundamental wave amplitude of the input current of the full-bridge rectifier circuit is as follows:
Figure FDA0002802897550000031
wherein, UbLoading a voltage for the wireless charging system; i isbCharging current for the wireless charging system; omega is the working angular frequency of the wireless charging system; l issAn inductor is input into the full-bridge rectifying circuit;
the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit is as follows:
Figure FDA0002802897550000032
7. the method for determining the equivalent load impedance of the rectifier circuit of the wireless charging system according to claim 1, wherein the determining the equivalent load impedance of the full bridge rectifier circuit of the wireless charging system based on the input current of the full bridge rectifier circuit and the tangent value of the fundamental phase angle and the load voltage of the wireless charging system comprises:
determining the sine value and the cosine value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit;
determining the fundamental wave amplitude and the fundamental wave phase angle of the input voltage of the full-bridge rectification circuit based on the load voltage of the wireless charging system;
using formulas
Figure FDA0002802897550000033
Determining an equivalent load impedance of a full-bridge rectification circuit of the wireless charging system; wherein R iseA resistance part of equivalent load impedance of a full-bridge rectifying circuit of the wireless charging system; l iseAn inductance part of equivalent load impedance of a full bridge rectification circuit of the wireless charging system; | AuI is the fundamental wave amplitude of the input voltage of the full-bridge rectification circuit; thetauThe fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; | AiI is the fundamental wave amplitude of the input current of the full-bridge rectification circuit; thetaiThe fundamental wave phase angle of the current is input into the full-bridge rectification circuit; omega is wireless charging system operating angular frequency.
8. The method for determining the equivalent load impedance of the rectifier circuit of the wireless charging system according to claim 7, wherein the determining the fundamental amplitude and the fundamental phase angle of the input voltage of the full-bridge rectifier circuit based on the load voltage of the wireless charging system specifically comprises:
using formulas
Figure FDA0002802897550000041
Determining the fundamental wave amplitude and the fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; wherein, | AuI is the fundamental wave amplitude of the input voltage of the full-bridge rectification circuit; thetauThe fundamental wave phase angle of the input voltage of the full-bridge rectification circuit; u shapebLoading the wireless charging system with a voltage.
9. The method of claim 7, wherein when the load in the wireless charging system is a battery-type load, the equivalent load impedance of the full-bridge rectifier circuit of the wireless charging system is:
Figure FDA0002802897550000042
wherein L issFor the input inductance, U, of a full-bridge rectifier circuitbFor wireless charging system load voltage, IbCharging current for the wireless charging system;
when the load in the wireless charging system is a resistance type load, the equivalent load impedance of the full-bridge rectifying circuit of the wireless charging system is as follows:
Figure FDA0002802897550000043
wherein R isLIs the load resistance value of the wireless charging system.
10. A system for determining an equivalent load impedance of a rectifier circuit of a wireless charging system, comprising:
the wireless charging system comprises a relation model determining module, a relation model calculating module and a relation model calculating module, wherein the relation model determining module is used for determining a relation model between the input current of the full-bridge rectifying circuit and an angle variable of the wireless charging system based on the working angle frequency of the wireless charging system and the input inductance of the full-bridge rectifying circuit;
the fundamental wave Fourier coefficient determining module of the input current of the full-bridge rectification circuit is used for obtaining the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit through Fourier transform based on a relation model between the input current of the full-bridge rectification circuit and an angle variable of the wireless charging system;
the device comprises a module for determining the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit, a module for determining the fundamental wave amplitude and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit according to the fundamental wave Fourier coefficient of the input current of the full-bridge rectification circuit;
the equivalent load impedance determination module of the full-bridge rectification circuit is used for determining the equivalent load impedance of the full-bridge rectification circuit of the wireless charging system based on the fundamental wave amplitude value and the tangent value of the fundamental wave phase angle of the input current of the full-bridge rectification circuit and the load voltage of the wireless charging system; the equivalent load impedance includes a resistive portion and an inductive portion.
CN202011357027.8A 2020-11-27 2020-11-27 Method and system for determining equivalent load impedance of rectifying circuit of wireless charging system Pending CN112583285A (en)

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