CN113422441A - High-efficiency voltage-stabilizing wireless charging system for electric automobile and design method thereof - Google Patents

High-efficiency voltage-stabilizing wireless charging system for electric automobile and design method thereof Download PDF

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CN113422441A
CN113422441A CN202110525687.0A CN202110525687A CN113422441A CN 113422441 A CN113422441 A CN 113422441A CN 202110525687 A CN202110525687 A CN 202110525687A CN 113422441 A CN113422441 A CN 113422441A
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circuit
voltage
efficiency
expression
wireless charging
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夏晨阳
李晓丽
杨子跃
杨旭浩
魏楠
廖志娟
刘锋
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Xuzhou Kester Electromechanical Technology Co ltd
China University of Mining and Technology CUMT
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Xuzhou Kester Electromechanical Technology Co ltd
China University of Mining and Technology CUMT
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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
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L53/00—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles
    • B60L53/10—Methods of charging batteries, specially adapted for electric vehicles; Charging stations or on-board charging equipment therefor; Exchange of energy storage elements in electric vehicles characterised by the energy transfer between the charging station and the vehicle
    • B60L53/12—Inductive energy transfer
    • 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
    • H02J7/007—Regulation of charging or discharging current or voltage
    • H02J7/00712—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters
    • H02J7/007182—Regulation of charging or discharging current or voltage the cycle being controlled or terminated in response to electric parameters in response to battery voltage
    • 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
    • H02M1/00—Details of apparatus for conversion
    • H02M1/44—Circuits or arrangements for compensating for electromagnetic interference in converters or inverters
    • 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
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac 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
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac 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 with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1582—Buck-boost converters
    • 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
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/70—Energy storage systems for electromobility, e.g. batteries
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T10/00—Road transport of goods or passengers
    • Y02T10/60—Other road transportation technologies with climate change mitigation effect
    • Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
    • 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
    • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
    • Y02T90/00—Enabling technologies or technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02T90/10—Technologies relating to charging of electric vehicles
    • Y02T90/14—Plug-in electric vehicles

Abstract

The invention provides a high-efficiency voltage-stabilizing wireless charging system of an electric automobile and a design method thereof, wherein the method comprises the following steps: constructing a mutual inductance circuit model of the system and a transmission efficiency expression thereof; solving an expression of an optimal load and an output power expression of the system under the optimal load based on the transmission efficiency expression; on the premise of optimal load, substituting the preset maximum duty ratio of the BUCK circuit and the maximum power of the system into the output power expression to obtain the ratio N of the primary side compensation inductance to the primary side coil inductance, and configuring the parameters of the LCC-S compensation circuit according to N; and adjusting the equivalent load value of the system through an impedance matching circuit to enable the equivalent load value to always follow the optimal load value so as to realize maximum efficiency tracking control. The invention can realize high-efficiency voltage-stabilizing charging of the high-power electric automobile storage battery, thereby improving the system performance.

Description

High-efficiency voltage-stabilizing wireless charging system for electric automobile and design method thereof
Technical Field
The invention relates to the technical field of wireless power transmission, in particular to a high-efficiency voltage-stabilizing wireless charging system for an electric vehicle and a design method thereof.
Background
At present, wireless charging technology is mostly adopted for electric automobiles. In the wireless charging process of the electric vehicle, the equivalent resistance of the storage battery type load of the electric vehicle is constantly changed, which results in low transmission efficiency of the whole wireless charging system.
In order to improve the transmission efficiency of the wireless charging system, the azolla, qiuzeli and chenhao publish a thesis named as maximum efficiency tracking of the WPT system based on optimal load matching, and the thesis designs an optimal impedance matching method based on phase-locked loop resonant frequency tracking and disturbance observation algorithm, so that the maximum efficiency tracking of the WPT system is realized. However, the solution proposed in this paper has the following problems:
(1) although the maximum efficiency tracking of the system is realized, the maximum efficiency value which can be reached is still low due to the unchanged system parameters;
(2) the disturbance observation algorithm is easy to generate errors, and meanwhile, the efficiency tracking speed is reduced;
(3) only the single output index of the system efficiency is considered, and the output voltage of the system is not subjected to voltage stabilization optimization.
Disclosure of Invention
The purpose of the invention is as follows: in order to overcome the defects of the prior art, the invention provides a high-efficiency voltage-stabilizing wireless charging system for an electric vehicle and a design method thereof, the system can reduce the dependence degree of a controller on a model, can realize the rapid and accurate output of constant voltage under the disturbance of a wide load range, and simultaneously improves the overall efficiency of the system and ensures the robust and stable characteristics of the system.
The technical scheme is as follows: in order to achieve the technical effects, the technical scheme provided by the invention is as follows:
a design method of a high-efficiency voltage-stabilizing wireless charging system of an electric automobile is characterized in that the charging system is an LCC-S type wireless electric energy transmission system and comprises a direct-current power supply, a primary side BUCK circuit, a high-frequency inverter, an LCC-S compensation circuit, a rectifying circuit, an impedance matching circuit and a load which are sequentially connected in series; the method comprises the following steps:
(1) constructing a mutual inductance circuit model of the system, and constructing a transmission efficiency expression of the mutual inductance circuit model;
(2) solving an expression of an optimal load and an output power expression of the system under the optimal load based on the transmission efficiency expression;
(3) under the premise of optimal load, presetting the maximum duty ratio D of the BUCK circuit1maxAnd the maximum power P of the systemomaxSubstituting the output power expression to obtain a ratio N of a primary side compensation inductance to a primary side coil inductance, and configuring parameters of the LCC-S compensation circuit according to N to enable the system to have the highest output power and the highest transmission efficiency of the mutual inductance circuit model under the optimal load;
(4) and adjusting the equivalent load value of the system through an impedance matching circuit to enable the equivalent load value to always follow the optimal load value so as to realize maximum efficiency tracking control.
Further, the design method further comprises the steps of: and performing linear active disturbance rejection voltage stabilization control on the primary side of the system to realize voltage stabilization output of the system under a variable load condition.
The invention further provides a high-efficiency voltage-stabilizing wireless charging system for the electric automobile, which is designed by adopting the design method.
Furthermore, in the high-efficiency voltage-stabilizing wireless charging system for the electric automobile, an LC filter circuit is further arranged at the front end of the LCC-S compensation circuit.
Specifically, in the high-efficiency voltage-stabilizing wireless charging system for the electric vehicle, the secondary impedance matching circuit is a BUCK-BOOST circuit, and the maximum efficiency tracking control method includes:
and when the BUCK-BOOST converter works in a continuous conduction mode, the equivalent load value is controlled to follow the optimal load value by controlling the switching tubes of the BUCK-BOOST circuit to be conducted and disconnected.
Specifically, a primary side of the system is provided with a first-order LADRC controller to realize linear active disturbance rejection voltage stabilization control, and the specific method comprises the following steps:
will output a voltage reference value UrefAs input to the LADRC controller, the first order linear extended state observer LESO has the expression:
Figure BDA0003063822190000021
wherein z is1Is the output voltage U of the systemoutEstimate of z2Is an estimate of the total disturbance of the system, beta1And beta2Is an adjustable parameter of the ESO;
and forming a control quantity u by disturbance compensation, wherein the expression is as follows:
Figure BDA0003063822190000022
wherein u is0Is the control quantity before compensation, b is the adjustable compensation factor, kpIs an adjustable proportionality coefficient;
and adjusting an adjusting signal of a switching tube in the primary side BUCK circuit through the control quantity u, so that the system is subjected to linear active disturbance rejection voltage stabilization control.
Has the advantages that: compared with the prior art, the invention has the following advantages:
1. the method improves the efficiency of the open loop system under the optimal load to the maximum extent by optimally designing the parameters of the LCC-S compensation topology; meanwhile, an impedance matching method is adopted to convert the actual load into an optimal impedance value, so that optimal efficiency tracking is realized.
2. The invention adopts the linear active disturbance rejection controller, reduces the number of parameter adjustment, improves the dynamic tracking performance and the anti-interference performance of the system, and is convenient for engineering application.
Drawings
Fig. 1 is a design flowchart of an efficient voltage-stabilizing wireless charging system for an electric vehicle according to an embodiment;
fig. 2 is a control device and a control schematic diagram of an electric vehicle high-efficiency voltage-stabilizing wireless charging system according to an embodiment;
FIG. 3 shows the optimal efficiency η of the high-efficiency voltage-stabilizing wireless charging system of the electric vehicle according to the embodimenttranoptA plot as a function of N;
FIG. 4 is a circuit diagram of an embodiment of a BUCK-BOOST circuit optimal efficiency tracking control circuit of the high-efficiency voltage-stabilizing wireless charging system for an electric vehicle;
FIG. 5 is a LADRC control diagram of an embodiment of a high efficiency regulated wireless charging system for an electric vehicle;
FIG. 6 is a comparison graph of output voltage and efficiency before and after optimization after voltage stabilization control is added to the high-efficiency voltage-stabilized wireless charging system of the electric vehicle according to the embodiment;
fig. 7 is a simulated waveform diagram of load voltage of the high-efficiency voltage-stabilizing wireless charging system of the electric automobile under the condition of variable load according to the embodiment.
Detailed Description
The invention will be further described with reference to the accompanying drawings and specific embodiments. It is to be understood that the present invention may be embodied in various forms, and that there is no intention to limit the invention to the specific embodiments illustrated, but on the contrary, the intention is to cover some exemplary and non-limiting embodiments shown in the attached drawings and described below.
Example 1:
the embodiment firstly exemplarily provides a circuit structure of the high-efficiency voltage-stabilizing wireless charging system of the electric vehicle as shown in fig. 2.
According to the charging requirement, because the LCC type resonance topology belongs to a composite resonance topology, 1) compared with four basic compensation topologies of an SS type, an SP type, a PS type and a PP type, the LCC-S compensation topology has the characteristics of load output voltage and primary side output current insensitive to load change, when a secondary side fails (is in short circuit or open circuit), the primary side is not influenced by the secondary side, and the stability and the safety of a system can be improved. 2) Compared with LCL compensation topology, the circuit has the advantages that one more capacitor is used as a free parameter, the total impedance of the system can be adjusted, zero-voltage switching is easier to realize, and accordingly conduction loss of a switching device is reduced. 3) Compared with a bilateral LCC topology, the compensation network only uses one compensation component, the complexity and the weight of the bilateral LCC topology can be reduced, and therefore the circuit topology that the LCC-S type topology is used for wirelessly charging the electric automobile is determined.
In view of the above analysis, the system shown in fig. 2 includes: the circuit comprises a primary side BUCK circuit, a high-frequency inverter, an LC filter circuit, an LCC-S compensation network circuit, a rectifying circuit, a BUCK-BOOST circuit, a maximum efficiency tracking control circuit and a linear active disturbance rejection voltage stabilization control circuit. In order to reduce the distortion rate of the output current of the inverter, an LC filter circuit is added at the front end of the LCC-S compensation network circuit. DC voltage source EdcThrough a filter capacitor CdcThe input end of the BUCK circuit is connected to provide power for the high-frequency inverter; the output end of the high-frequency inverter is connected with the LC filter circuit, the LC filter circuit is connected with the LCC compensation network on the primary side in series, the output end of the LCC-S compensation network circuit is connected with the input end of the rectifying circuit, the output end of the rectifying circuit is connected with the impedance matching network circuit, and finally the impedance matching network circuit is connected with the load. BUCK circuit routing MOSFETSaDiode DaInductance LaAnd a filter CaAnd (4) forming. The high-frequency inverter is composed of four MOSFET tubes V1-V4For generating a high frequency current to drive the primary coil. LC filter circuit is composed of inductor LFAnd a capacitor CFComposition for filtering invertersThe output higher harmonics. The LCC-S compensation topology network comprises: self-inductance L of primary coilpAnd a compensation inductance LrAnd a compensation capacitor CpAnd a compensation capacitor CxSelf-inductance L of secondary coilsAnd a compensation capacitor Cs。Rp、RsThe internal resistances of the primary coil and the secondary coil respectively; m is the mutual inductance between primary and secondary windings, RLIs a load. The rectifier circuit consists of four uncontrollable diodes D1-D4The output signal of which passes through a filter capacitor CbSuppressing high-frequency signals and reducing ripples of output voltage; the BUCK-BOOST circuit comprises: MOSFET SbDiode DbInductance LbAnd a filter Cf. The output voltage of the BUCK-BOOST circuit passes through a filter capacitor CfAnd finally supplying power to the load after filtering.
The maximum efficiency tracking control circuit comprises a sampling module, a controller 1 and a secondary duty ratio D2The PWM driving circuit of (1). The sampling module comprises: the voltage sensor and the current sensor are used for acquiring voltage and current values and outputting the voltage and current values to be connected to the controller 1 for calculation processing; the sampling module is connected to the load, the sampling module, the controller 1 and the secondary duty ratio D2The PWM driving circuit is sequentially connected with the MOSFET switching tube S in the BUCK-BOOST circuitbIs connected with the control end of the controller.
The linear active-disturbance-rejection voltage-stabilizing control circuit comprises a voltage detection module, a wireless communication module, a linear active-disturbance-rejection controller 2 and a primary side duty ratio D1The PWM driving circuit of (1); the wireless communication module includes: the device comprises a radio frequency transmitting module and a radio frequency receiving module. The input end of the voltage detection module is connected with a load, the voltage detection module, the wireless communication module, the linear active-disturbance-rejection controller 2 and the primary side duty ratio D1The PWM driving circuits are sequentially connected and finally correspondingly connected with the control end of the BUCK circuit.
Based on the above system, the present embodiment further exemplarily provides a design method of the high-efficiency voltage-stabilizing wireless charging system for an electric vehicle, and the flow of the design method is shown in fig. 1, and specifically includes the following steps:
step 1: and (5) initializing and setting the system.
Determining expected output index of wireless charging of electric automobile and rated output voltage U of electric automobileoutIs 20V, the maximum output power Pomax2000W is required to be achieved, and the transmission efficiency eta of the system is giventranNot less than 90 percent. Firstly, system level basic parameters are set, and a direct current voltage value E is determineddcIs L of the 260V, LC filter circuitF106.24 uH and CF33nF, primary and secondary coil inductance LpAnd LsAre all 111 mu H, secondary side compensation capacitor Cs31nF, a resonance frequency f of 85kHz and a mutual inductance M of 35 muh. Defining N as primary side compensation inductance LrInductance L with primary coilpI.e. N ═ Lr/Lp。
Step 2: and optimizing compensation network parameters.
(21) System transmission efficiency eta is calculated based on system mutual inductance circuit modeltranIs described in (1).
(22) To etatranObtaining the optimal load R by calculating the partial derivativeLeoptThe expression is as follows:
Figure BDA0003063822190000041
wherein R isp(Rs) Is parasitic internal resistance, R, of the primary (secondary) windingrRepresenting the inductance LFAnd LrThe sum of the internal resistances.
(23) Output power P at optimum loadLeoptAnd ηtranoptThe expression for efficiency is
Figure BDA0003063822190000042
Formula (2) shows that the output power of the system under the optimal load is only equal to the duty ratio D of the BUCK circuit1Related to N, the optimum efficiency eta of the system at this point in time shown in FIG. 3tranoptIs positively correlated with N. The optimization goal is to make the optimal efficiency as high as possible while satisfying the output power over a wide load range of the system. Assuming rectifier bridge and impedance matching circuitThe paths are all ideal devices, so the actual output power PoEqual to the power P of the AC loadLe。
(24) Selecting the maximum duty ratio D of the BUCK circuit according to the actual charging requirement of the electric automobile1max0.9, practical minimum load RLminIs 0.2 omega and a reference voltage value UrefIs 20V.
(25) By using
Figure BDA0003063822190000053
Calculating the maximum power P required by the systemomaxAt 2000W, the duty ratio D of the BUCK circuit1To a maximum value D1maxLet the output power P of the optimum loadLeoptIs equal to PomaxSolving to obtain the N value of 0.21 and the optimal load RLeoptThe solution is 48 omega.
The optimal parameter set of the compensation network topology can be obtained through the steps, and the system circuit parameters are configured.
And step 3: and (4) optimal efficiency tracking control.
FIG. 4 is a circuit diagram of the BUCK-BOOST circuit optimum efficiency tracking control circuit. The secondary side impedance matching circuit is a BUCK-BOOST circuit, whether the resistance value of the load changes is checked, and if the resistance value of the load changes, the optimal load expression R of the system is calculated based on the resistance value of the loadLeoptWhen the BUCK-BOOST converter works in a Continuous Conduction Mode (CCM), an equivalent load R is established according to the law of energy conservationLeActual load RLAnd duty ratio D of BUCK-BOOST converter2The relationship between them is:
Figure BDA0003063822190000051
wherein, UoutAnd IoutRespectively the output voltage and the output current of the system. The sampling module is used for collecting voltage current signals on the load, and the duty ratio D is obtained by calculating the load and the optimal load value through the multiplier2Inputting the voltage to an analog circuit, and then regulating a BUCK-BOOST circuit switch tube S through a PWM driving circuitbTurn on and off to enable the rectified inputThe equivalent load remains unchanged; if the load resistance value is not changed, the optimal efficiency is directly output. The process can ensure that the system always works in the optimal efficiency state.
And 4, step 4: and (5) linear active disturbance rejection voltage stabilization control.
Fig. 5 is a larc control diagram of the wireless charging system of the electric vehicle according to the present invention. In order to solve the problem of poor interference resistance and rapidity, the wireless charging system of the electric automobile adopts first-order LADRC to perform voltage regulation control, and the system is ensured to realize constant voltage output. The method comprises the following specific steps: will output a voltage reference value UrefAs an input to the LADRC controller. The first-order linear extended state observer LESO is expressed as follows, omitting the transition process
Figure BDA0003063822190000052
Wherein z is1Is the output voltage U of the wireless charging system of the electric automobileoutEstimate of z2Is an estimate of the total disturbance of the system. Beta is a1And beta2Is a tunable parameter of ESO. The disturbance compensation forms a control quantity u, which is expressed as follows
Figure BDA0003063822190000061
Wherein u is0Is the control quantity before compensation, b is the adjustable compensation factor, kpIs an adjustable scaling factor. The parameters of the controller meeting the output index are generated through continuous debugging, and the voltage detection module collects the load voltage UoutSending the voltage into a linear active disturbance rejection controller which generates a tracking output voltage UoutIs a state variable z1，z1And an output voltage reference value UrefCalculating the deviation e by an adder, and using an active disturbance rejection controller to calculate the deviation e as Uref-z1And further calculating and processing to obtain the voltage control quantity u. PWM driving circuit converts active disturbance rejection control quantity u into duty ratio D1＝u/VmIn which V ismRepresenting the amplitude of the modulation, where V is setmIs 260. Control signal generated by PWM drive circuit controls switching tube S of BUCK circuitaTherefore, voltage regulation control is carried out on the wireless charging system of the electric automobile.
In order to verify the technical effect of the invention, the invention is experimentally verified. FIG. 6 is a graph comparing output voltage after voltage regulation control is added and efficiency before and after optimization. After the voltage stabilizing control is added, the voltage value is stabilized at the reference value of 20V no matter how the load changes. The fixed DC-DC converter circuit duty ratio is not changed, namely when the optimal efficiency tracking control is not added, the efficiency is gradually reduced after being increased; after the optimal efficiency tracking control is added, the efficiency is almost kept unchanged and is stabilized at about 96.5 percent.
Fig. 7 is a simulation waveform diagram of the load voltage under the variable load condition, in which the output reference voltage is set to 20V and the simulation time is set to 0.03 s. When the set time is 0.015s, the load is switched from 10 omega to 5 omega, and the system tracks and outputs the reference voltage after about 1ms, so that the steady-state voltage value is 20V. The theoretical value of the efficiency is basically maintained to be about 96% through simulation calculation. The design method and the control system for the high-efficiency voltage-stabilizing wireless charging of the electric automobile, provided by the invention, have the advantages that the maximum efficiency tracking and constant voltage output of the system are realized, and the adaptability to load change is realized. In order to improve the system efficiency, the efficiency of the open-loop system under the optimal load is improved as much as possible by optimizing parameters of a compensation network. And realizing optimal efficiency tracking by adopting an active impedance matching method based on BUCK-BOOST. The voltage regulation adopts a first-order linear active disturbance rejection controller to ensure that the system outputs constant voltage under the condition of load disturbance. The optimal efficiency tracking and voltage stabilization control method is decoupled, so that the two methods can be operated independently without complex operation.
And finally, checking whether the output of the system can reach an expected index or not, wherein the result shows that the output voltage of the system can be maintained at 20V no matter how the load changes, the efficiency of the system is stabilized at about 96.5 percent, and the expected index of the wireless charging output of the electric automobile is met.
It is to be understood that the features listed above for the different embodiments may be combined with each other to form further embodiments within the scope of the invention, where technically feasible. Furthermore, the particular examples and embodiments of the invention described are non-limiting, and various modifications may be made in the structure, steps, and sequence set forth above without departing from the scope of the invention.

Claims (6)

1. A design method of a high-efficiency voltage-stabilizing wireless charging system of an electric automobile is characterized in that the charging system is an LCC-S type wireless electric energy transmission system and comprises a direct-current power supply, a primary side BUCK circuit, a high-frequency inverter, an LCC-S compensation circuit, a rectifying circuit, an impedance matching circuit and a load which are sequentially connected in series; characterized in that the method comprises the following steps:
(1) constructing a mutual inductance circuit model of the system, and constructing a transmission efficiency expression of the mutual inductance circuit model;
(2) solving an expression of an optimal load and an output power expression of the system under the optimal load based on the transmission efficiency expression;
(3) under the premise of optimal load, presetting the maximum duty ratio D of the BUCK circuit1maxAnd the maximum power P of the systemomaxSubstituting the output power expression to obtain a ratio N of a primary side compensation inductance to a primary side coil inductance, and configuring parameters of the LCC-S compensation circuit according to N to enable the system to have the highest output power and the highest transmission efficiency of the mutual inductance circuit model under the optimal load;
(4) and adjusting the equivalent load value of the system through an impedance matching circuit to enable the equivalent load value to always follow the optimal load value so as to realize maximum efficiency tracking control.
2. The design method of the high-efficiency voltage-stabilizing wireless charging system of the electric automobile according to claim 1, further comprising the steps of: and performing linear active disturbance rejection voltage stabilization control on the primary side of the system to realize voltage stabilization output of the system under a variable load condition.
3. An efficient voltage-stabilizing wireless charging system for an electric vehicle, which is designed by the method according to any one of claims 1 to 2.
4. The wireless charging system of claim 3, wherein an LC filter circuit is further disposed at the front end of the LCC-S compensation circuit.
5. The wireless charging system of claim 3, wherein the secondary impedance matching circuit is a BUCK-BOOST circuit, and the maximum efficiency tracking control method is:
and when the BUCK-BOOST converter works in a continuous conduction mode, the equivalent load value is controlled to follow the optimal load value by controlling the switching tubes of the BUCK-BOOST circuit to be conducted and disconnected.
6. The wireless charging system of claim 3, wherein a first-order LADRC controller is arranged on a primary side of the system to realize linear auto-disturbance rejection voltage stabilization control, and the method comprises the following steps:
will output a voltage reference value UrefAs input to the LADRC controller, the first order linear extended state observer LESO has the expression:
Figure FDA0003063822180000011
wherein z is1Is the output voltage U of the systemoutEstimate of z2Is an estimate of the total disturbance of the system, beta1And beta2Is an adjustable parameter of the ESO;
and forming a control quantity u by disturbance compensation, wherein the expression is as follows:
Figure FDA0003063822180000012
wherein u is0Is the control quantity before compensation, b is the adjustable compensation factor, kpIs an adjustable proportionality coefficient;
and adjusting an adjusting signal of a switching tube in the primary side BUCK circuit through the control quantity u, so that the system is subjected to linear active disturbance rejection voltage stabilization control.
CN202110525687.0A 2021-05-13 2021-05-13 High-efficiency voltage-stabilizing wireless charging system for electric automobile and design method thereof Pending CN113422441A (en)

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113824193A (en) * 2021-10-27 2021-12-21 四川大学 Impedance matching method, impedance matching device, reinforcement learning controller and computer readable storage medium
CN114844188A (en) * 2022-03-25 2022-08-02 中国电子科技集团公司第二十九研究所 BOOST energy storage circuit matched with dynamic load change circuit

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113824193A (en) * 2021-10-27 2021-12-21 四川大学 Impedance matching method, impedance matching device, reinforcement learning controller and computer readable storage medium
CN113824193B (en) * 2021-10-27 2023-05-23 四川大学 Impedance matching method, apparatus, reinforcement learning controller, and computer-readable storage medium
CN114844188A (en) * 2022-03-25 2022-08-02 中国电子科技集团公司第二十九研究所 BOOST energy storage circuit matched with dynamic load change circuit
CN114844188B (en) * 2022-03-25 2024-02-02 中国电子科技集团公司第二十九研究所 Circuit for matching dynamic load change of BOOST energy storage circuit

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