CN115603468A - EC-WPT system based on frequency switching constant current/constant voltage output and parameter design method thereof - Google Patents

EC-WPT system based on frequency switching constant current/constant voltage output and parameter design method thereof Download PDF

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CN115603468A
CN115603468A CN202211277417.3A CN202211277417A CN115603468A CN 115603468 A CN115603468 A CN 115603468A CN 202211277417 A CN202211277417 A CN 202211277417A CN 115603468 A CN115603468 A CN 115603468A
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constant
current
value
voltage
output
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苏玉刚
颜志琼
胡宏晟
赵雷
孙跃
戴欣
唐春森
王智慧
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Chongqing University
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    • 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
    • H02J50/05—Circuit arrangements or systems for wireless supply or distribution of electric power using capacitive 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
    • 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
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/01—Resonant DC/DC converters
    • H02M3/015—Resonant DC/DC converters with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuit
    • 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
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/22—Conversion of dc power input into dc power output with intermediate conversion into ac
    • H02M3/24—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters
    • H02M3/28—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac
    • H02M3/325—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal
    • H02M3/335—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/33569—Conversion of dc power input into dc power output with intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode to produce the intermediate ac using devices of a triode or a transistor type requiring continuous application of a control signal using semiconductor devices only having several active switching elements
    • H02M3/33573—Full-bridge at primary side of an isolation transformer
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/4815—Resonant converters
    • H02M7/4818—Resonant converters with means for adaptation of resonance frequency, e.g. by modification of capacitance or inductance of resonance circuits
    • 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
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac 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
    • H02M7/537—Conversion of dc power input into ac 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, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac 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, e.g. single switched pulse inverters in a bridge configuration
    • H02M7/53871—Conversion of dc power input into ac 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, e.g. single switched pulse inverters in a bridge configuration with automatic control of output voltage or current
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B70/00—Technologies for an efficient end-user side electric power management and consumption
    • Y02B70/10—Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Inverter Devices (AREA)

Abstract

The invention relates to the technical field of EC-WPT (EC-WPT), and particularly discloses an EC-WPT system based on frequency switching constant current/constant voltage output and a parameter design method thereof. The EC-WPT system and the parameter design method proposed herein have the following advantages: a complex detection and control circuit is not needed, and the system can realize constant current/constant voltage output under the condition of load change; the switching between the constant-current working mode and the constant-voltage working mode can be realized only by switching the working frequency without switching the circuit topology; the system can realize a ZPA (zero phase angle) state no matter in a constant-current working mode or a constant-voltage working mode, so that the reactive loss is reduced, and the system efficiency is effectively improved; the system has relatively few compensating elements, and the complexity of the system can be reduced.

Description

EC-WPT system based on frequency switching constant current/constant voltage output and parameter design method thereof
Technical Field
The invention relates to the technical field of EC-WPT (electric field coupling wireless power transmission), in particular to an EC-WPT system based on frequency switching constant current/constant voltage output and a parameter design method thereof.
Background
The Wireless Power Transfer (WPT) technology combines Power electronics technology with modern control theory and technology, and realizes Wireless Power Transfer through Magnetic field, electric field, microwave, laser and other carriers, and the common Wireless charging mode adopts Magnetic Coupling Wireless Power Transfer (MC-WPT) technology and Electric field Coupling Wireless Power Transfer (EC-WPT) technology, which have the following advantages: the coupling mechanism has low cost, light weight and easy shape change; the electromagnetic interference around the coupling mechanism is low; energy can be transmitted across metal barriers; eddy current losses caused between the coupling means or on the surrounding metal conductors are small. Therefore, the research on the EC-WPT technology can complement the advantages of the MC-WPT technology, and further expand the application field of the WPT technology. At present, a plurality of achievements are achieved in the aspects of high-frequency inverter design, compensation of a coupling mechanism, output voltage stabilization control, parallel transmission of energy and signals, resonance topology optimization, transmission distance amplification and the like.
In the practical application of the WPT technology, some electric devices need systems with different constant output characteristics (constant current/constant voltage) at different operation stages, that is, system output voltage or output current is decoupled from a load, and in addition, the systems need to have a function of switching between constant current and constant voltage modes as required. For example, when a lithium battery is charged wirelessly, a charging mode of constant current first and constant voltage later is adopted in the charging process of the battery, and at the beginning stage, the system needs to work in the constant current mode, and the voltage rises rapidly at the moment. When the voltage rises to the rated value, the system needs to switch to constant voltage mode.
In the related research of EC-WPT technology, the prior document mainly focuses on two methods to realize the output constancy of the system, and the first method is to provide a detection circuit at the output end of the system, and feed back the detected load voltage to a control circuit at the transmitting end, so as to realize the constant output. The second method is to use the characteristics of the resonant network to achieve a constant output of the system. In contrast, the latter does not need to provide detection and complex control circuits, and has the advantages of lower complexity and cost of the system. At present, two-sided F-CLCL resonant network and T-pi composite resonant network are respectively adopted in documents to ensure that the output voltage of the system does not change along with the change of the load. There is also literature on making a bilateral LC resonant network system with constant output voltage characteristics through parametric design. There is literature that bilateral LC resonant network systems have characteristics of constant output current through parametric design. There is also a document that proposes a T-type CLC resonant network that enables the system output voltage to be constant. The resonant network in the above documents can only singly enable the system to realize constant voltage output or constant current output, and the document proposes an F-F/T variable structure resonant network to realize the switching of the constant current/constant voltage working mode of the system, in order to meet the requirements of not only realizing constant current power supply but also realizing constant voltage power supply and mode switching thereof in practical application; in the other documents, a variable-structure LC-CLCL resonant network is adopted to realize the switching of a constant-current/constant-voltage working mode of the system; in both of the two modes, a control switch needs to be added in the resonant network, and the on-off of the control switch is needed to realize switching between the constant-current working mode and the constant-voltage working mode. The additional switching devices add cost and bulk to the system and affect the reliability of the system.
Disclosure of Invention
The invention provides an EC-WPT system based on frequency switching constant current/constant voltage output and a parameter design method thereof, and solves the technical problems that: how to meet the requirement that the system of the electric equipment has different constant output characteristics (constant current/constant voltage) at different operation stages, namely the system output voltage or output current is decoupled with a load, in addition, the system also needs to have the function of switching between constant current and constant voltage modes as required, and keeps higher transmission efficiency.
In order to solve the technical problems, the invention provides an EC-WPT system based on frequency switching constant current/constant voltage output, which comprises a transmitting end and a receiving end, wherein the transmitting end is provided with a direct current power supply, a high-frequency inverter, an LC resonance network and two energy transmitting polar plates, and the receiving end is provided with two energy receiving polar plates, a CLC resonance network, a rectifying and filtering circuit and an electric load; when the system needs constant voltage output, the high-frequency inverter operates according to the constant voltage working frequency f cv Outputting a high-frequency inversion signal; when the system needs constant current output, the high-frequency inverter operates according to the constant current working frequency f cc Outputting a high-frequency inversion signal; the LC resonance network comprises an inductance L 1 Capacitor C 1 Inductance L 1 And a capacitor C 1 Connected in series between two output terminals of the high-frequency inverter at a capacitor C 1 The two ends of the energy transmitting pole plate are respectively and correspondingly connected with the two energy transmitting pole plates; the CLC-pi type resonant network comprises an inductor L 2 Capacitor C 2 Capacitor C 3x At a capacitance C 2 Are respectively correspondingly connected with the two energy receiving polar plates at the two ends of the capacitor C 3x Are respectively correspondingly connected with the rectifying and filtering circuit and the inductor L 2 Is connected in series to a capacitor C 2 And a capacitor C 3x In the middle of;
order to
Figure BDA0003897015320000031
Coupling capacitor C s ＝(C s1 C s2 )/(C s1 +C s2 )，C s1 Is approximately equal to C 13 ，C s2 Is approximately equal to C 24 ，C 13 For energy-emitting electrode plate P 1 And an energy receiving pole plate P 3 A capacitance formed therebetween, C 24 To be at leastVolume emission polar plate P 2 And an energy receiving plate P 4 A capacitance formed therebetween, a capacitance C 3x Is equivalent to a capacitor C together with a rectifying and filtering circuit 3 ，α＝C 1 /C s 、β＝C 2 /C s 、k＝C 3 /C 2 The LC resonant network and the CLC- Π resonant network then satisfy the relationship for three defined correlation coefficients:
Figure BDA0003897015320000032
and, constant voltage operating frequency f cv And constant current operating frequency f cc The following relation is satisfied:
Figure BDA0003897015320000033
preferably, constant output voltage of the system
Figure BDA0003897015320000034
And constant effective value of output current
Figure BDA0003897015320000035
Comprises the following steps:
Figure BDA0003897015320000036
Figure BDA0003897015320000037
is the output voltage of the high frequency inverter.
Preferably, 500kHz<f cc <f cv <2MHz。
Preferably, the high-frequency inverter adopts a high-frequency full-bridge inverter circuit consisting of 4 MOSFETs.
Preferably, the rectifying and filtering circuit comprises a full-bridge rectifying circuit consisting of 4 diodes and a filtering capacitor C f 。
The invention also provides a parameter design method of the EC-WPT system based on frequency switching constant current/constant voltage output, which comprises the following steps:
s1, setting constant-voltage working frequency f according to engineering experience cv A value of (d);
s2, determining a constant output current I according to actual requirements L And constant output voltage U L Determining the coupling capacitance C according to the coupling mechanism s Size;
s3, enabling the constant output voltage U L Theoretical value of (U) L-theoretical value ＝U L Constant output current I L Theoretical value of (I) L-theoretical value ＝I L The set value of (2);
s4, according to U L-theoretical value 、I L-theoretical value And calculating the DC input voltage E of the DC power supply according to the voltage-current relation of the system dc A value of (d);
s5, calculating C according to a voltage-current capacitance-inductance relational expression of the system 1 、C 2 、C 3 、L 1 、L 2 And f cc A value of (d);
s6, judging constant output voltage U L Actual value of (U) L _ actual If the value is equal to the set value, the step S7 is carried out if the value is equal to the set value, otherwise, U is further judged L _ actual The magnitude relation between the current value and the set value is that if the U is judged L _ actual Increasing U when less than the set value L-theoretical value And returning to the step S4, if the U is judged L _ actual If it is greater than the set value, U is decreased L-theoretical value And returning to the step S4;
s7, judging constant output current I L Actual value of (I) L _ actual If the value is equal to the set value, the step S8 is entered if the value is equal to the set value, otherwise, the step I is further judged L _ actual The relationship between the current value and the set value is I L _ actual Is less than the set value, increases I L-theoretical value And returning to the step S4, if I is judged L _ actual Is decreased by more than its set value L-theoretical value And returning to the step S4;
s8, taking C 3x Initial value of (C) 3 ；
S9, judging whether the system reaches a zero phase angle state or not, and if so, obtaining a group of C meeting the conditions 1 、C 2 、C 3x 、L 1 、L 2 And f cc Value of parameter, if not, decrease C 3x Until the system reaches a zero phase angle state.
Further, in step S4, the voltage-current relation of the system includes:
Figure BDA0003897015320000041
Figure BDA0003897015320000042
Figure BDA0003897015320000051
further, in step S5, the voltage-current capacitance-inductance relation of the system includes:
Figure BDA0003897015320000052
Figure BDA0003897015320000053
Figure BDA0003897015320000054
Figure BDA0003897015320000055
the EC-WPT system based on frequency switching constant current/constant voltage output and the parameter design method thereof adopt the LC-CLC resonant network, analyze the characteristics of the LC-CLC resonant network, provide conditions for realizing the constant current/constant voltage output characteristics and a calculation method of constant current frequency and constant voltage frequency, provide a system parameter design method, realize the switching of constant current/constant voltage working modes through switching frequency, and finally verify the constant current/constant voltage output characteristics of the system and the effectiveness of the parameter design method through simulation and experiment. The EC-WPT system and the parameter design method proposed herein have the following advantages:
1) A complex detection and control circuit is not needed, and the system can realize constant current/constant voltage output under the condition of load change;
2) The switching of the constant-current/constant-voltage working mode can be realized only by switching the working frequency without switching the circuit topology;
3) The system can realize a ZPA (zero phase angle) state no matter in a constant-current working mode or a constant-voltage working mode, so that the reactive loss is reduced, and the system efficiency is effectively improved;
4) The system has relatively few compensating elements, and can reduce the complexity of the system and improve the reliability of the system.
Drawings
FIG. 1 is a topology diagram of an EC-WPT system provided by an embodiment of the present invention;
FIG. 2 is an equivalent circuit model diagram of a coupling mechanism according to an embodiment of the present invention;
FIG. 3 is an equivalent circuit diagram of an EC-WPT system provided by an embodiment of the present invention;
FIG. 4 is a flow chart of parameter design of an EC-WPT system provided by an embodiment of the present invention;
FIG. 5 is a graph of phase, output current and voltage versus operating frequency provided by an embodiment of the present invention;
FIG. 6 shows an example of L provided by embodiments of the present invention 1 A graph of the influence on the output characteristics;
FIG. 7 shows a block diagram C according to an embodiment of the present invention 1 Influence situation graph on output characteristics;
FIG. 8 is a drawing of a graph C according to an embodiment of the present invention 2 Influence situation graph on output characteristics;
FIG. 9 shows an example of L provided by an embodiment of the present invention 2 Influence situation graph on output characteristics;
FIG. 10 is a drawing of a graph C according to an embodiment of the present invention 3 Influence situation graph on output characteristics;
FIG. 11 is a simulated waveform diagram of the inverted output voltage and current provided by an embodiment of the present invention;
FIG. 12 shows an example of a constant current mode R L ＝24Ω、R L ＝38Ω、R L =48 Ω and R in constant voltage mode L ＝24Ω、R L ＝38Ω、R L Simulation oscillogram of inversion output voltage and current when =48 Ω;
FIG. 13 is a simulated waveform diagram of load current and voltage provided by an embodiment of the present invention;
FIG. 14 is an experimental waveform diagram of a constant current mode of operation provided by an embodiment of the present invention;
FIG. 15 is a waveform diagram illustrating an experiment of a constant voltage operation mode according to an embodiment of the present invention;
fig. 16 is an experimental waveform diagram corresponding to switching between constant current/constant current operating modes according to an embodiment of the present invention;
fig. 17 is a graph of output power and transmission efficiency as a function of load provided by an embodiment of the present invention;
fig. 18 is a graph of output voltage and output current versus load provided by an embodiment of the present invention.
Detailed Description
The embodiments of the present invention will be described in detail below with reference to the accompanying drawings, which are given solely for the purpose of illustration and are not to be construed as limitations of the invention, including the drawings which are incorporated herein by reference and for illustration only and are not to be construed as limitations of the invention, since many variations thereof are possible without departing from the spirit and scope of the invention.
The embodiment of the invention provides an EC-WPT system based on frequency switching constant current/constant voltage output, which comprises a transmitting end and a receiving end, wherein the transmitting end is provided with a direct current power supply, a high-frequency inverter, an LC resonance network and two energy transmitting polar plates, and the receiving end is provided with two energy receiving polar plates, a CLC-pi type resonance network, a rectifying and filtering circuit and two energy receiving polar platesAnd (4) using an electric load. The system architecture is shown in FIG. 1, where E dc Is a direct current input voltage; s 1 -S 4 The high-frequency full-bridge inverter circuit consists of 4 MOSFETs; the primary resonant network is an LC resonant network (including an inductor L) 1 Capacitor C 1 Inductance L 1 And a capacitor C 1 Connected in series between two output terminals of the high-frequency inverter at a capacitor C 1 The two ends of the energy emitting pole plate are respectively and correspondingly connected with the two energy emitting pole plates); the secondary side resonant network is a CLC-pi type resonant network (comprising an inductor L) composed of two capacitors and an inductor 2 Capacitor C 2 Capacitor C 3x At a capacitor C 2 Are respectively correspondingly connected with the two energy receiving polar plates at the two ends of the capacitor C 3x Are respectively correspondingly connected with the rectification filter circuit and the inductor L 2 Is connected in series to a capacitor C 2 And a capacitor C 3x In (d) of the first and second groups; d 1 -D 4 The full-bridge rectifying circuit is composed of 4 diodes; c f Is a filter capacitor; r L Is the load equivalent resistance. When the receiving polar plate of the coupling mechanism is placed near the transmitting polar plate, an interactive electric field is generated between the two polar plates, and displacement current is generated to flow through the polar plates under the action of the interactive electric field, so that wireless transmission of electric energy is realized. The rectifier filter converts the alternating current into direct current to supply power to the battery.
The cross-coupling between the four plates of the coupling mechanism shown in fig. 1 can be equivalent to the six-capacitor equivalent model shown in fig. 2 (a). C 12 And C 34 Are respectively a polar plate P 1 -P 2 And P 3 -P 4 The formed capacitors are respectively positioned at the energy transmitting end and the receiving end; c 13 And C 24 Are respectively a polar plate P 1 -P 3 And P 2 -P 4 The formed capacitor forms an energy transmission channel; c 23 And C 14 Are respectively a polar plate P 2 -P 3 And P 1 -P 4 The formed capacitance; the six-capacitor equivalent model may be further equivalent to the pi model shown in fig. 2 (b). To tight couplingFor the parallel coupling mechanism, when the same side plates are on the same horizontal plane and far away from each other, the coupling capacitance C of the same side plates 12 And C 34 Nearly zero and cross-coupling capacitance C 14 And C 23 Much smaller than the coupling capacitance C between the positive and the negative plates 13 And C 24 . At this time, the coupling mechanism may be equivalent to a two-capacitance equivalent model as shown in fig. 2 (C), where C s1 Approximately equal to C 13 ，C s2 Approximately equal to C 24 。
In the topology shown in fig. 1, the internal resistance of the inductor and the equivalent series resistance of the capacitor are usually small relative to their own impedance, and for the sake of simplifying the analysis, the internal resistance of the inductor and the equivalent series resistance of the capacitor can be ignored, and the system can be equivalent to the circuit shown in fig. 3, where C s ＝(C s1 C s2 )/(C s1 +C s2 ). In FIG. 1, the input end of the rectifier is connected with a capacitor C in parallel 3x Resulting in an input voltage u of the rectifier o Input current i other than square wave 4 Nor sinusoidal and the voltage lags the current, so the rectifier, filter capacitor and load R L Can be equivalent to a capacitor and a resistor R eq Parallel connection, so C should be considered when designing circuit parameters 3x <C 3 Wherein the equivalent resistance R eq Satisfy R eq ＝8R L /π 2 。
U in FIG. 3 in Is an inverted output voltage which is expanded by a Fourier trigonometric series formula, i.e.
Figure BDA0003897015320000081
Where ω is the angular frequency of operation of the system, and ω =2 π f is satisfied with the frequency of operation f. Because the resonance compensation network of the system can filter out most higher harmonics, the Fundamental Harmonic Approximation (FHA) method can be adopted to analyze the circuit, and then the Fundamental Harmonic Approximation (FHA) method can be obtained
Figure BDA0003897015320000082
Can be expressed as in a vector form
Figure BDA0003897015320000083
Similarly, the input voltage current and the output voltage current of the rectifier have the same approximate relationship
Figure BDA0003897015320000084
U in formula (4) L And I L Are respectively a resistance R L Voltage u across L Average value of (1) and flowing current i L Average value of (1), U o And I o Is R in the equivalent circuit eq The effective value of the voltage across the terminals and the effective value of the flowing current.
In the equivalent circuit diagram of fig. 3, in the constant voltage operation mode, the operating frequency of the system is f cv Corresponding to an operating angular frequency of ω cv Inductance L 1 And L 2 Respectively connected with a capacitor C 1 、C 2 Resonance, i.e. the parameter relationship, satisfies:
Figure BDA0003897015320000091
assume a capacitance C 1 、C 2 、C 3 And equivalent coupling capacitance C s The relationship between them is:
Figure BDA0003897015320000092
α＝C 1 /C s 、β＝C 2 /C s 、k＝C 3 /C 2 three correlation coefficients are defined.
From kirchhoff's voltage law, the following system of equations can be obtained:
Figure BDA0003897015320000093
wherein X L1 、X c1 、X cs 、X c2 、X L2 、X c3 Are each L 1 、C 1 、C s 、C 2 、L 2 And C 3 The impedance of (c). The input current of the system can be obtained from equation (7)
Figure BDA0003897015320000094
And an output voltage
Figure BDA0003897015320000095
The expression of (a) is:
Figure BDA0003897015320000096
it can be seen from equation (8) that when the system satisfies the resonance condition shown in equation (5), the output voltage of the system is independent of the load, and the system can achieve a constant voltage output, and that in order to operate in the ZPA state when the system outputs a constant voltage, the input impedance of the system should be purely resistive, and the input current will be input
Figure BDA0003897015320000097
Should be 0, i.e. the system should satisfy the following relation:
Figure BDA0003897015320000098
at an operating frequency f cv Time, inductance L 1 、L 2 A capacitance C satisfying the resonance condition of the formula (5) 3 Satisfies expression (9), so L 1 、L 2 And C 3 Can be expressed as:
Figure BDA0003897015320000101
the output current can be obtained from the formula (7)
Figure BDA0003897015320000102
The expression of (a) is:
Figure BDA0003897015320000103
wherein G is 1 And G 2 Is two and R eq An expression that is irrelevant. To make the output current independent of the load, the frequency omega is constant-current cc Lower, G 1 Should be equal to 0.
Setting α and β to satisfy:
Figure BDA0003897015320000104
by substituting formula (12), formula (10) and formula (6) for formula (7), G can be obtained 1 With two solutions of =0 respectively
Figure BDA0003897015320000105
In fig. 3, the impedance in the equivalent circuit is as follows:
Figure BDA0003897015320000106
when ω is cc ＝ω cc1 Input impedance Z of the system 6 Comprises the following steps:
Figure BDA0003897015320000111
obviously, the imaginary input impedance is not 0, and the system cannot achieve the ZPA state.
When ω is cc ＝ω cc2 Input impedance Z of the system 6 Comprises the following steps:
Figure BDA0003897015320000112
at this time, the imaginary part of the input impedance of the system is 0, the system can realize the ZPA state, and the output current of the system
Figure BDA00038970153200001110
Comprises the following steps:
Figure BDA0003897015320000113
it can be seen that the output current
Figure BDA0003897015320000114
Only with input voltage
Figure BDA0003897015320000115
Equivalent coupling capacitor C of coupling mechanism s Constant voltage operating frequency omega cv And the capacitance ratio alpha is related to the load, so that the system can realize constant current output.
From the analysis and derivation in the two previous sections, the compensation element of the system needs to satisfy the condition in equation (18) if the system can switch between the two constant current/constant voltage operation modes by switching the frequency:
Figure BDA0003897015320000116
if the compensation parameter satisfies the formula (18), the constant-voltage operating frequency f of the system cv And constant current operating frequency f cc Respectively as follows:
Figure BDA0003897015320000117
the constant output voltage of the system can be found from the equations (8), (17) and (18)
Figure BDA0003897015320000118
And constant output current
Figure BDA0003897015320000119
Comprises the following steps:
Figure BDA0003897015320000121
the system parameter design flow is shown in fig. 4. At present, the working frequency of most EC-WPT systems is within the range of 500 kHz-2 MHz, and if the working frequency is too high, the dynamic loss and the electromagnetic interference of the systems are large; too small a frequency results in a large compensation inductance of the system and a low quality factor and power density of the system. In addition, if the equivalent coupling capacitance of the coupling mechanism is larger, the working frequency can be designed to be smaller, and if the equivalent coupling capacitance of the coupling mechanism is too small, the working frequency is required to be larger. F is aligned in the range of 500 kHz-2 MHz according to the analysis and engineering requirements cv And carrying out reasonable value taking. Since the theoretical derivation above is based on fundamental approximation, we use the practically required constant output voltage U L Magnitude and constant output current I L When the magnitude is used as a theoretical value to calculate the system element parameter, the actual DC output voltage U is obtained L And the actual DC output current I L Generally not of the required size, so that U L And I L The theoretical value of (a) needs to be adjusted by a small margin; furthermore, from the above analysis, C 3x Is less than the capacitance value C calculated by the equivalent circuit 3 Thus in determining the parameter C 3x When, C can be firstly 3x Is given as C 3 When the waveforms of the output voltage and current of the inverter in the constant voltage mode are observed through simulation, the system should be capacitive rather than in the ZPA state, and C should be reduced 3x Until the whole system reaches the ZPA state.
Specifically, referring to fig. 4, a method for designing parameters of an EC-WPT system based on frequency switching constant-current constant-voltage output according to an embodiment of the present invention includes:
s1, setting constant-voltage working frequency f according to engineering experience cv A value of (d);
s2, determining a constant output current I according to actual requirements L And constant output voltage U L Set value (I) of L And U L Respectively representing the load current i L And the voltage u across the load L Average value of) of the coupling mechanisms, the coupling capacitance C is determined according to the coupling mechanism s Size;
s3, enabling the constant output voltage U L Theoretical value of (U) L-theoretical value ＝U L Constant output current I L Theoretical value of (I) L-theoretical value ＝I L The set value of (2); a
S4, according to U L-theoretical value 、I L-theoretical value And calculating the DC input voltage E of the DC power supply by using the voltage-current relational expressions of the system including the expressions (3), (4) and (20) dc A value of (d);
s5, calculating C according to the voltage, current, capacitance and inductance relational expressions of the system, including expression (20), expression (18), expression (19) and expression (4) 1 、C 2 、C 3 、L 1 、L 2 And f cc A value of (d);
s6, judging constant output voltage U L Actual value of (U) L _ actual If the value is equal to the set value, the step S7 is carried out if the value is equal to the set value, otherwise, U is further judged L _ actual The relationship between the current value and the set value is that if the U is judged L _ actual Increasing U when less than the set value L-theoretical value And returning to the step S4, if the U is judged L _ actual If it is greater than the set value, U is decreased L-theoretical value And returning to the step S4;
s7, judging constant output current I L Actual value of (I) L _ actual If the value is equal to the set value, the step S8 is entered if the value is equal to the set value, otherwise, the step I is further judged L _ actual The relationship between the current value and the set value is I L _ actual Is less than the set value, increases I L-theoretical value And returning to the step S4, if I is judged L _ actual Is decreased by more than its set value L-theoretical value And returning to the step S4;
s8, taking C 3x Initial value of (C) 3 ；
S9, judging whether the system reaches a zero phase angle state or not, and if so, obtaining a group of C meeting the conditions 1 、C 2 、C 3x 、L 1 、L 2 And f cc Value of parameter, if not, decrease C 3x Until the system reaches a zero phase angle state.
The following was a system sensitivity analysis.
In practical application, the inverter has deviation due to the fact that the error of a control circuit cannot accurately reach a certain frequency point, if the system is too sensitive to frequency, the constant current/constant voltage output characteristics of the system are affected, and therefore the sensitivity of the system to the working frequency must be analyzed.
At present, the rated input of lithium batteries is mostly 96V/2A, 72V/2A and 48V/2A, so taking the output voltage of 96V in a system constant voltage output mode and the output current of 2A in a constant current mode as an example, the maximum value and the minimum value of load resistance are respectively set to be 72 omega and 24 omega. Setting equivalent coupling capacitance C of coupling mechanism s At 0.5nF, and a constant voltage operating frequency of 800kHz, a set of parameters was designed as shown in table 1 according to the flow chart shown in fig. 4, the constant current operating frequency of the system was 706.6kHz, and a given dc input voltage E was applied dc Was 47V.
TABLE 1 values of the parameters calculated theoretically
Figure BDA0003897015320000131
FIG. 5 shows the voltage U L Current I L And the variation curve of the system input phase angle along with the working frequency. As can be seen from fig. 5, the system has two ZPA operating frequency points, at which there are respectively a constant current operating frequency and a constant voltage operating frequency, consistent with the theoretical design described above. In addition, at a constant current frequency f cc In the range of +/-4 kHz, the system has a good constant current effect; at constant voltage frequency f cv Within the range of +/-5 kHz, the system has better constant-pressure effect. Therefore, the inverter can ensure the system within the error range of 0.5 percentHas better constant current/constant voltage output characteristics.
In practical application, when the system works, the compensation element parameters of the resonant network inevitably deviate from theoretical values thereof due to the influence of environmental factors such as heat generation and the like, and if the output characteristics of the system are too sensitive to the variation of the element parameters, when the deviation generated by the element parameters is too large, the constant current/constant voltage output characteristics of the system are seriously influenced. Therefore, the parameter sensitivity of the resonant network must be analyzed.
The system takes the parameters in table 1, and the influence of the parameter change of each element on the output characteristics is shown in fig. 6-10. Voltage U without deviation of element parameters L And current I L The theoretical values of (A) are respectively about 96V and 2A, the system is in a ZPA state, the input phase angle is 0 degree, and U is taken L Is + -2V, I L Has a tolerance of + -0.2A and a tolerance of + -10 DEG for the input phase angle.
As can be seen in FIG. 6, in the constant current mode of operation, the resistor R L The smaller, L 1 The larger the allowable value range is, the larger the resistor R is in the constant voltage working mode L The larger, L 1 The larger the allowable value range. Output voltage U under two working modes of comprehensively considering constant current/constant voltage L Output current I L And allowable deviation of input phase angle, L 1 Values can be taken in the range of 12.76uH to 13.2uH. Similarly, C can be derived from FIG. 7 1 The range of values that can be taken is 2.992nF to 3.143nF; as can be seen from fig. 8 (a), the constant current output characteristic of the system, C, is ensured 2 It can have a large value range, i.e. 1.452 nF-1.6 nF, but it can be seen from FIG. 8 (b) that the system constant voltage output is to C 2 Very sensitive, can only take values between 1.518nF and 1.538nF, so C 2 The value range of (A) is 1.518 nF-1.538 nF; from FIG. 9, L can be derived 2 The range of values can be 25.79 uH-26.07 uH; in FIG. 10, C can be derived 3 The range of values that can be taken is 6.36nF to 7.539nF;
in order to verify the constant current/constant voltage output characteristics of the designed EC-WPT system and the effectiveness of parameter design, the circuit topology shown in FIG. 1 and the designed parameters in Table 1 are used. And establishing a corresponding simulation model by using a MATLAB/Simulink simulation platform.
FIG. 11 shows the system inverter output voltage u in And current i 1 The simulation oscillogram of (2) can be seen from the graph, at the moment of switching the working frequency, the inversion output current has only slight sudden change, and at other switching points, the inversion output current has almost no sudden change, so that the system reliability is high. FIG. 12 shows R in constant current mode L ＝24Ω、R L ＝38Ω、R L =48 Ω and R in constant voltage mode L ＝24Ω、R L ＝38Ω、R L And (3) a simulated waveform diagram of the inversion output voltage and current when the current is 48 omega, wherein the diagram shows that the system is basically in a ZPA state no matter in a constant current mode or a constant voltage mode, and the simulation is consistent with the theoretical design.
FIG. 13 shows the DC output voltage u L And a DC output current i L A simulated waveform diagram of (c). Within 0-0.03 s, the working frequency is 706.6kHz, and the system works in a constant current mode; at time 0.01s, the load resistance R L Switched from 24 Ω to 38 Ω, current i L From 2.11A to 2.06A; at time 0.02s, the load resistance R L Switched from 38 omega to 48 omega with current i L From 2.06A to 2.02A; at the time of 0.03s, the working frequency is switched to 800kHz, the system enters a constant voltage working mode, and the voltage is quickly stabilized at 95.4V after oscillation; at time 0.04s, the load resistance R L Switched from 48 Ω to 60 Ω and at a voltage u L From 95.4V to 96.4V; at time 0.05s, the load resistance R L Switched from 60 omega to 72 omega at a voltage u L From 96.4V to 97.2V. It can be seen that in the constant current mode of operation, when the load resistance changes by 50%, the current i L Only 1.8% change occurred; in the constant voltage operation mode, when the load resistance changes by 50%, the voltage u L Only a 1.8% change occurred. Therefore, the system has better constant current/constant voltage output characteristics under the load change.
Experimental verification is performed below.
To further verify the above theoretical analysis, based on simulation verification, the system topology and table shown in FIG. 1 are used2, the experimental device is constructed. The power supply provides 48V DC voltage and constant current working frequency f cc =695kHz, constant-voltage operating frequency f cv =790kHz. The parameters set in the experiment have a small deviation from the theory, because the influence of the system internal resistance and parasitic parameters is not considered in the theoretical derivation.
TABLE 2 values of the experimental parameters
Figure BDA0003897015320000151
FIG. 14 shows the inverted output voltage u in the constant current mode in And an inverted output current i 1 The load end outputs a DC voltage u L And current i L Experimental waveform diagram (c). Wherein FIG. 14 (a) is R L An experimental waveform diagram in the constant-current operating mode when =25 Ω, and as can be seen from the diagram, the current i L At 2.03A, the output current i is inverted 1 Slightly lagging inverted output voltage u in The method is beneficial to realizing Zero Voltage Switching (ZVS) of the system, reducing switching loss and improving transmission efficiency. FIG. 14 (b) shows the system I/O with the load R operating in constant current mode L Varying experimental waveform, load R at switching Point 1 L Switching from 30 Ω to 60 Ω, current i L Change from 2A to 1.86A, load R at switching Point 2 L Switching from 60 Ω to 30 Ω, current i L From 1.86A to 2A. Experimental data show that under larger load disturbance, the current i L Only 7% of the total output voltage is reduced, and the constant current output characteristic is better.
FIG. 15 (a) shows R L Experimental wave form diagram under constant voltage working mode at 48 Ω, voltage u L Inverse output current i of about 97.3V 1 Slightly lagging inverted output voltage u in To implement system Zero Voltage Switching (ZVS). FIG. 15 (b) shows the system I/O with the load R operating in the constant voltage mode L Varying experimental waveform, load R at switching Point 1 L Switching from 55 omega to 80 omega, voltage u L Changing from 97.5V to 99V, load R at switching point 2 L Switch from 55 Ω to 80 Ω and voltage u L From 99V to 97.5V. The experimental data show thatAt large load disturbances, the voltage u L Only 1.5% of the voltage is increased, and the constant voltage output characteristic is better.
FIG. 16 is a view of the load R L When the system is switched between two working modes of constant current and constant voltage in the case of 48 omega, the output voltage u is inverted in Inverting output current i 1 The load end outputs a DC voltage u L And current i L Experimental waveform diagram (c). At switching point 1, the operating frequency of the system is from f cc Switch to f cv Voltage u L And current i L Are slightly increased because of the influence of the internal resistance and parasitic parameters of the system, which causes the constant current operation of the system along with the load R L The current will decrease slightly; at switching point 2, the operating frequency of the system is from f cv Switch to f cc At the time of switching between two operating modes, the input current i of the system 1 The system can be switched smoothly at any time without excessive impact.
FIG. 17 is output power and transmission efficiency as a function of R L In constant current mode, the transmission efficiency of the system is as a function of R L Is increased when R is increased L Output power of 103.23W and transmission efficiency of 77.6% when 25 Ω, when R is satisfied L When =32 Ω, the output power is 130.69W, the transmission efficiency is 83.78%, and when R is satisfied L When =48 Ω, the output power is 185.6W, and the transmission efficiency is 87.83%; in constant pressure mode of operation, at R L When 48 Ω, the output power was 197.23W, the efficiency was 87.2%, and R was measured L =60 Ω, output power 161.54W, efficiency 88.17%, and R L And =70 Ω, the output power is 140W, and the efficiency is 85.87%. Therefore, the system has higher transmission efficiency no matter in a constant-current working mode or a constant-voltage working mode.
FIG. 18 shows the current i in the experiment L And voltage u L With load R L Of the change in (a), theoretical current i L Is constant at 2A, voltage u L Is constant at 96V, but actually, the current i L Will follow the load R L Is increased and decreased by a small amount, the voltage u L Will follow the load R L Is increased with a small amount. The errors are mainly caused by three reasons, the first reason is that the theory is proposed based on a fundamental wave approximation method, and a small amount of errors are generated when higher harmonics act on a system; the second reason is that the internal resistance of the system components and some parasitic parameters are not taken into account in the theoretical derivation. The third reason is when the filter capacitor C f When the resistance is not large enough, the output voltage of the filter circuit is slightly influenced by the size of the resistance.
In summary, the embodiment of the invention provides a constant current/constant voltage EC-WPT system based on an LC-CLC resonant network, which realizes switching of working modes by switching frequencies, around the fact that electric devices need systems with different constant output characteristics (constant current/constant voltage) at different operation stages, i.e., system output voltage or output current is decoupled from a load, and has a need for switching between constant current and constant voltage modes as needed. The method comprises the steps of deducing the parameter conditions of constant current/constant voltage output of the system under the condition of load change, providing a system parameter design method, analyzing the sensitivity of the working frequency of the system and the parameter sensitivity of the resonant network compensation element, obtaining the insensitivity of the system to the working frequency and the error range allowed by each compensation element, and finally verifying the constant current/constant voltage output characteristics of the system and the effectiveness of the parameter design method through simulation and experiments. The EC-WPT system and the parameter design method proposed herein have the following advantages:
1) And a complex detection and control circuit is not needed, and the system can realize constant current/constant voltage output under the condition of load change.
2) The switching of the constant-current/constant-voltage working modes can be realized only by switching the working frequency without switching the circuit topology.
3) No matter in constant current mode or constant voltage mode, the system can realize ZPA state, reduces reactive loss, effectively promotes system efficiency.
4) The system has relatively few compensating devices, can reduce the complexity of the system and improve the reliability of the system.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such modifications are intended to be included in the scope of the present invention.

Claims (8)

1. The EC-WPT system based on frequency switching constant current/constant voltage output comprises a transmitting end and a receiving end, wherein the transmitting end is provided with a direct current power supply, a high-frequency inverter, an LC resonance network and two energy transmitting polar plates, and the receiving end is provided with two energy receiving polar plates, a CLC-pi type resonance network, a rectifying and filtering circuit and an electric load; when the system needs constant voltage output, the high-frequency inverter operates according to the constant voltage working frequency f cv Outputting a high-frequency inversion signal; when the system needs constant current output, the high-frequency inverter operates according to the constant current working frequency f cc Outputting a high-frequency inversion signal; the LC resonance network comprises an inductance L 1 Capacitor C 1 Inductance L 1 And a capacitor C 1 Connected in series between two output terminals of the high-frequency inverter at a capacitor C 1 The two ends of the energy transmitting pole plate are respectively and correspondingly connected with the two energy transmitting pole plates; the CLC-pi type resonant network comprises an inductor L 2 Capacitor C 2 Capacitor C 3x At a capacitor C 2 Are respectively correspondingly connected with the two energy receiving polar plates at the two ends of the capacitor C 3x Are respectively correspondingly connected with the rectifying and filtering circuit and the inductor L 2 Is connected in series to a capacitor C 2 And a capacitor C 3x In the middle of; the method is characterized in that:
order to
Figure FDA0003897015310000011
Coupling capacitor C s ＝(C s1 C s2 )/(C s1 +C s2 )，C s1 Is equal to C 13 ，C s2 Is equal to C 24 ，C 13 For energy-emitting electrode plate P 1 And an energy receiving pole plate P 3 A capacitance formed therebetween, C 24 For energy-emitting electrode plate P 2 And an energy receiving pole plate P 4 A capacitance formed therebetween, a capacitance C 3x Is equivalent to electricity together with a rectifying and filtering circuitContainer C 3 ，α＝C 1 /C s 、β＝C 2 /C s 、k＝C 3 /C 2 The LC resonant network and the CLC- Π resonant network then satisfy the relationship for three defined correlation coefficients:
Figure FDA0003897015310000012
and, constant voltage operating frequency f cv And constant current operating frequency f cc The following relation is satisfied:
Figure FDA0003897015310000013
2. the EC-WPT system based on frequency switching constant current/constant voltage output of claim 1, wherein the constant output voltage of the system
Figure FDA0003897015310000021
And constant output current
Figure FDA0003897015310000022
Comprises the following steps:
Figure FDA0003897015310000023
Figure FDA0003897015310000024
is the output voltage of the high frequency inverter.
3. The EC-WPT system for switching constant current/constant voltage output based on frequency according to claim 1, wherein: 500kHz<f cc <f cv <2MHz。
4. The EC-WPT system based on frequency switching constant current/constant voltage output according to claim 1, wherein the high frequency inverter adopts a high frequency full bridge inverter circuit composed of 4 MOSFETs.
5. The EC-WPT system based on frequency switching constant current/constant voltage output of claim 1, wherein the rectifying and filtering circuit comprises a full-bridge rectifying circuit consisting of 4 diodes and a filtering capacitor C f 。
6. The parameter design method of the EC-WPT system based on frequency switching constant current/constant voltage output according to any one of claims 2 to 5, characterized by comprising the steps of:
s1, setting constant-voltage working frequency f according to engineering experience cv A value of (d);
s2, determining a constant output current I according to actual requirements L And constant output voltage U L Determining the coupling capacitance C according to the coupling mechanism s Size;
s3, enabling the direct current side to output a constant voltage U L Theoretical value of (U) L-theoretical value ＝U L Constant output current I L Theoretical value of (I) L-theoretical value ＝I L The set value of (2);
s4, according to U L-theoretical value 、I L-theoretical value And calculating the DC input voltage E of the DC power supply according to the voltage-current relation of the system dc A value of (d);
s5, calculating C according to a voltage-current capacitance-inductance relational expression of the system 1 、C 2 、C 3 、L 1 、L 2 And f cc A value of (d);
s6, judging constant output voltage U L Actual value of (U) L _ actual If the value is equal to the set value, the step S7 is carried out if the value is equal to the set value, otherwise, U is further judged L _ actual The magnitude relation between the current value and the set value is that if the U is judged L _ actual Increasing U below its set value L-theoretical value And returning to the step S4, if the U is judged L _ actual If it is greater than the set value, U is decreased L-theoretical value And returning to the step S4;
s7, judging constant output current I L Actual value of (I) L _ actual If the value is equal to the set value, the step S8 is entered if the value is equal to the set value, otherwise, the step I is further judged L _ actual The relationship between the current value and the set value is I L _ actual Is less than the set value, increases I L-theoretical value And returning to the step S4, if I is judged L _ actual Is greater than the set value, is decreased by I L-theoretical value And returning to the step S4;
s8, taking C 3x Initial value of (C) 3 ；
S9, judging whether the system reaches a zero phase angle state or not, and if so, obtaining a group of C meeting the conditions 1 、C 2 、C 3x 、L 1 、L 2 And f cc Parameter value, if not, decrease C 3x Until the system reaches a zero phase angle state.
7. The method for designing parameters of the EC-WPT system based on frequency switching constant current/constant voltage output according to claim 6, wherein in step S4, the voltage-current relationship of the system comprises:
Figure FDA0003897015310000031
Figure FDA0003897015310000032
Figure FDA0003897015310000033
8. the method for designing parameters of the EC-WPT system based on frequency switching constant current/constant voltage output as claimed in claim 6, wherein in step S5, the voltage-current capacitance-inductance relationship of the system comprises:
Figure FDA0003897015310000041
Figure FDA0003897015310000042
Figure FDA0003897015310000043
Figure FDA0003897015310000044
CN202211277417.3A 2022-10-19 2022-10-19 EC-WPT system based on frequency switching constant current/constant voltage output and parameter design method thereof Pending CN115603468A (en)

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN116191691A (en) * 2023-03-15 2023-05-30 中国人民解放军海军工程大学 Electric field type wireless power transmission compensation system, design method, device and design method
CN116191691B (en) * 2023-03-15 2024-03-15 中国人民解放军海军工程大学 Electric field type wireless power transmission compensation system, design method, device and design method

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