CN112737142A - Mutual inductance detection method and control method of wireless charging system and corresponding system - Google Patents

Mutual inductance detection method and control method of wireless charging system and corresponding system Download PDF

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CN112737142A
CN112737142A CN202011554847.6A CN202011554847A CN112737142A CN 112737142 A CN112737142 A CN 112737142A CN 202011554847 A CN202011554847 A CN 202011554847A CN 112737142 A CN112737142 A CN 112737142A
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wireless charging
compensation
frequency
charging system
mutual inductance
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CN112737142B (en
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刘玮
胡超
罗勇
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Zhongxing New Energy Technology Co ltd
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Zhongxing New Energy Technology Co ltd
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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
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/005—Testing of electric installations on transport means
    • G01R31/006—Testing of electric installations on transport means on road vehicles, e.g. automobiles or trucks
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
    • H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
    • H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
    • H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from 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
    • Y02T10/70—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

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Charge And Discharge Circuits For Batteries Or The Like (AREA)

Abstract

The invention discloses a mutual inductance detection method and a control method of a wireless charging system and a corresponding system, wherein the mutual inductance detection method of the wireless charging system comprises the following steps: controlling a full-bridge rectification circuit of a receiving end to be in a short-circuit state, controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range, identifying resonance frequency points of a compensation capacitor and a compensation inductor of the receiving end, and calculating a mutual inductance value of the wireless charging system by combining measured electrical parameters under the resonance frequency points, namely a current value on a transmitting coil and current voltage values at two ends of the compensation inductor of the receiving end. According to the invention, the electrical parameters of the receiving end when the compensation inductance and the compensation capacitance resonate or approach to resonate are obtained to obtain a relatively accurate mutual inductance value, so that the engineering error of the compensation parameters of the receiving end can be eliminated, and the detection precision is greatly improved; and the accurate mutual inductance value is incorporated into the system control, so that the performance and the stability of the system are greatly improved.

Description

Mutual inductance detection method and control method of wireless charging system and corresponding system
Technical Field
The invention relates to the technical field of wireless charging, in particular to a mutual inductance detection method and a mutual inductance control method of a wireless charging system and a corresponding system.
Background
The application of the wireless charging technology in the field of electric automobiles is gradually popularized, and in engineering application, as the position between ground equipment and vehicle-mounted equipment is in an undetermined state along with a parking state, and an automobile chassis can also change within a certain range along with the loading state in a vehicle, the horizontal offset distance and the vertical distance (ground clearance) between a primary coil and a secondary coil of a loose coupling transformer of a wireless charging system can change within a certain range, and thus the mutual inductance value of the loose coupling transformer changes along with the change. In engineering application, in order to improve the stability of a wireless charging system and improve the system performance, a control scheme is generally carried out according to mutual inductance values, so that the accurate mutual inductance values are of great importance to system control.
The existing mutual inductance value detection method generally enables a system to work under a rated frequency, and the system works by detecting some electrical parameters and calculating according to the design values of loosely coupled transformer parameters and/or system compensation parameters. In practical engineering applications, engineering errors may exist in both the parameters of the loosely coupled transformer and the compensation parameters, and these errors may cause errors in the calculated value of the mutual inductance. When the accumulation of errors is large, the mutual inductance calculated value may be shifted far from the actual value, and if the mutual inductance calculated value with large errors is included in the system control, the system performance may be affected.
Disclosure of Invention
In view of the foregoing problems, an object of the present invention is to provide a mutual inductance detection method, a mutual inductance control method, and a corresponding system for a wireless charging system, which can eliminate engineering errors of compensation parameters, obtain accurate mutual inductance parameters, and perform system control by using the accurate mutual inductance parameters, thereby improving system performance. The technical scheme is as follows:
the embodiment of the invention provides a mutual inductance detection method of a wireless charging system, wherein the wireless charging system comprises a transmitting end and a receiving end, the transmitting end comprises a transmitting coil, and the receiving end comprises a receiving coil, a compensation capacitor, a compensation inductor and a full-bridge rectifying circuit, wherein the output end of the receiving coil is connected to the input end of the full-bridge rectifying circuit through the compensation inductor, the input end of the compensation capacitor is connected with the input end of the compensation inductor, and the output end of the compensation capacitor is connected with the output end of the receiving coil and the input end of the full-bridge rectifying circuit; the mutual inductance detection method comprises the following steps:
controlling the full-bridge rectifying circuit to be in a short-circuit state;
controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range;
monitoring a real-time current value on the transmitting coil;
sampling real-time voltage at two ends of the compensation inductor and real-time current on the receiving coil;
identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and/or the real-time voltage at two ends of the compensation inductor;
and calculating to obtain a mutual inductance value of the wireless charging system according to the resonance frequency, the corresponding current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor.
Preferably, the monitoring of the real-time current value on the transmitting coil may further be:
and under each working frequency of the wireless charging system, correspondingly adjusting the input voltage at two ends of the transmitting coil, and monitoring the real-time current value on the transmitting coil to be unchanged.
Preferably, the identifying the resonant frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil specifically includes:
comparing the real-time current values on the receiving coils to obtain a minimum current value;
and acquiring the current working frequency corresponding to the minimum current value, namely the resonance frequency of the compensation capacitor and the compensation inductor.
Preferably, the identifying the resonant frequency of the compensation capacitor and the resonant frequency of the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and the real-time voltage at two ends of the compensation inductor specifically includes:
comparing the phase relationship between the real-time current on the receiving coil and the real-time voltage at the two ends of the compensation inductor;
and acquiring the phase relation as the current working frequency when the resistance is adopted, namely the resonance frequency of the compensation capacitor and the compensation inductor.
Preferably, the preset frequency range takes the designed resonance frequency of the compensation capacitor and the compensation inductor as the center frequency.
Preferably, the mutual inductance value M of the wireless charging system is calculated by the following formula:
Figure BDA0002855949160000031
wherein f is the resonant frequency of the compensation capacitor and the compensation inductor, IpAnd U is the current value of the transmitting coil corresponding to the resonance frequency, and is the current voltage value at two ends of the compensation inductor corresponding to the resonance frequency.
Another embodiment of the present invention provides a wireless charging control method, which specifically includes:
acquiring mutual inductance parameters of the wireless charging system by using the mutual inductance detection method of the wireless charging system;
and controlling system parameters of the wireless charging system to be adjusted according to the mutual inductance parameters so as to improve the system performance.
The invention further provides a mutual inductance detection system of a wireless charging system, the wireless charging system comprises a transmitting end and a receiving end, the transmitting end comprises a transmitting coil, and the receiving end comprises a receiving coil, a compensation capacitor, a compensation inductor and a full-bridge rectifying circuit, wherein the output end of the receiving coil is connected to the input end of the full-bridge rectifying circuit through the compensation inductor, the input end of the compensation capacitor is connected with the input end of the compensation inductor, and the output end of the compensation capacitor is connected with the output end of the receiving coil and the input end of the full-bridge rectifying circuit; mutual inductance detection system includes circuit control unit, frequency control unit, monitoring unit, sampling unit, frequency identification unit, and the computational unit specifically is:
the circuit control unit is used for controlling the full-bridge rectifying circuit to be in a short-circuit state;
the frequency control unit is used for controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range;
the monitoring unit is used for monitoring a real-time current value on the transmitting coil;
the sampling unit is used for sampling the real-time voltage at two ends of the compensation inductor and the real-time current on the receiving coil;
the frequency identification unit is used for identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and/or the real-time voltage at the two ends of the compensation inductor;
and the calculating unit is used for calculating to obtain a mutual inductance value of the wireless charging system according to the resonant frequency, the corresponding current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor.
Preferably, the monitoring unit includes a regulating module and a monitoring module, and specifically includes:
the adjusting module is used for correspondingly adjusting the input voltage at two ends of the transmitting coil under each working frequency of the wireless charging system;
and the monitoring module is used for monitoring the real-time current value on the transmitting coil to be unchanged.
Preferably, the frequency identification unit includes a comparison module and a frequency acquisition module, and specifically includes:
the comparison module is used for comparing the real-time current value on the receiving coil to obtain the minimum current value;
the frequency obtaining module is configured to obtain a current working frequency corresponding to the minimum current value, which is a resonant frequency of the compensation capacitor and the compensation inductor.
Preferably, the frequency identification unit includes a comparison module and a frequency acquisition module, and specifically includes:
the comparison module is used for comparing the phase relation between the real-time current on the receiving coil and the real-time voltage at the two ends of the compensation inductor;
the frequency obtaining module is configured to obtain a current working frequency when the phase relationship is resistive, that is, a resonant frequency of the compensation capacitor and the compensation inductor.
Another embodiment of the present invention provides a wireless charging control system, including the mutual inductance detection system and the parameter control unit of the wireless charging system as described above;
the parameter control unit is used for controlling system parameters of the wireless charging system to be adjusted according to mutual inductance parameters acquired by the mutual inductance detection system of the wireless charging system so as to improve system performance.
According to the technical scheme, before power transmission of the wireless charging system, the full-bridge rectification circuit of the receiving end is in a short-circuit state, the wireless charging system is controlled to work in a frequency conversion mode within a preset frequency range, resonance frequency points of a compensation capacitor and a compensation inductor of the receiving end are identified, measured electrical parameters under the resonance frequency points, namely a current value on a transmitting coil and current voltage values at two ends of the compensation inductor of the receiving end are combined, and a mutual inductance value of the wireless charging system is calculated, so that the control system controls system parameters of the wireless charging system to be adjusted according to the mutual inductance value. Therefore, the embodiment of the invention obtains a relatively accurate mutual inductance value by obtaining the electrical parameters when the compensation inductance and the compensation capacitance of the receiving end resonate or approach to resonate, can eliminate the engineering error of the compensation parameters of the receiving end, and greatly improves the detection precision; and the accurate mutual inductance value is incorporated into the system control, so that the performance and the stability of the system are greatly improved.
Drawings
In order to more clearly illustrate the technical solution of the present invention, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.
Fig. 1 is a flowchart of a method for detecting mutual inductance of a wireless charging system according to a first embodiment of the present invention.
Fig. 2 is a schematic structural diagram of a wireless charging system according to a first embodiment of the present invention.
Fig. 3 is a schematic structural diagram of the wireless charging system in a short-circuit state according to the first embodiment.
Fig. 4 is a graph of a current value on the receiving coil according to the first embodiment of the present invention, which is changed with an operating frequency of the wireless charging system.
Fig. 5 is a flowchart of a method of controlling wireless charging according to the second embodiment.
Fig. 6 is a system configuration diagram of a mutual inductance detection system of a wireless charging system according to a third embodiment.
Fig. 7 is a system configuration diagram of a wireless charging control system according to a fourth embodiment.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
In addition, if there is a description of "first", "second", etc. in the embodiments of the present application, the description of "first", "second", etc. is for descriptive purposes only and is not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In addition, technical solutions between various embodiments may be combined with each other, but must be realized by a person skilled in the art, and when the technical solutions are contradictory or cannot be realized, such a combination should not be considered to exist, and is not within the protection scope of the present application.
Example one
Referring to fig. 1, a flowchart of a method for detecting mutual inductance of a wireless charging system is shown.
Referring to fig. 2, a schematic structural diagram of a wireless charging system is shown, the wireless charging system includes a transmitting end and a receiving end, the transmitting end includes a transmitting coil LPThe receiving end comprises a receiving coil LSAnd a compensation capacitor C1And a compensation inductance L1And a full-bridge rectification circuit 1, the transmitting coil LPAnd the receiving coil LSPrimary and secondary windings of a loosely coupled transformer, i.e. a transmitter and a receiver of energy, respectively, the currents being IPAnd IS. The transmitting terminal further comprises a full-bridge inverter circuit 2, wherein the full-bridge rectifier circuit 1 is composed of four switching tubes QS1、QS2、QS3And QS4The inverter circuit 2 is composed of four switching tubes QP1、QP2、QP3And QP4The switch tube is connected in a bridge form, and specifically, the switch tube can be one of switch devices such as a mos tube and an insulated gate bipolar transistor. The full-bridge inverter circuit 2 is responsible for converting direct current into high-frequency power, and the full-bridge rectifier circuit 1 is responsible for rectifying the high-frequency power and outputting current IoutCarrying out adjustment; the compensation inductance L1Is connected to the receiving coil LSAnd the compensation capacitor C1The input terminal of, the compensation inductance L1Is connected with a bridge arm central point of the full-bridge rectification circuit 1, and the compensation capacitor C1Is connected with the receiving coil LSAnd the full-bridge rectifierThe other leg center point of way 1. The input current of the full-bridge rectification circuit 1 is IeAt a midpoint voltage of VeThen its equivalent resistance Re＝Ve/Ie。
In this embodiment, the mutual inductance detection method includes steps S11 to S16, which are specifically as follows:
and S11, controlling the full-bridge rectifying circuit to be in a short-circuit state.
Fig. 3 is a schematic structural diagram of a wireless charging system in a short-circuit state. Preferably, the full-bridge rectifier circuit 1 is in a short-circuit state, specifically, Q in the full-bridge rectifier circuit 1S1And QS2On, or QS3And QS4When the full-bridge rectification circuit 1 is conducted, the midpoint voltage V of the full-bridge rectification circuit 1 iseIs 0, its equivalent resistance ReAlso 0. When the wireless charging system is started, the mutual inductance value can be determined according to the transmitting coil LPThe upper current and the induced voltage of the receiving terminal are calculated, but the mutual inductance value cannot be directly obtained because the induced voltage of the receiving terminal cannot be directly measured. However, when the compensation capacitor C1And the compensation inductance L1When the parallel resonance is carried out, the circuit is broken, and at the moment, the induction voltage of the receiving end is directly loaded on the compensation capacitor C1And the compensation inductance L1Thus, by measuring the compensation capacitance C at that time1Or the compensation inductance L1And (4) calculating an accurate mutual inductance value.
And S12, controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range.
Preferably, the predetermined frequency range is determined by the compensation capacitor C1And the compensation inductance L1The design resonant frequency of (1) is the center frequency. In particular, the design resonant frequency f0Can be based on the compensation capacitance C1And the compensation inductance L1Is determined by the following formula:
Figure BDA0002855949160000071
wherein l10For said compensation inductance L1Design value of c10For said compensation capacitor C1Design value of (c).
Therefore, the predetermined frequency range is [ f0-Δf，f0+Δf]The frequency error Δ f is determined by the compensation capacitor C1And the compensation inductance L1Is determined according to the error range which can exist in the practical engineering application.
Preferably, in step S12, specifically, the method includes: controlling the wireless charging system at a frequency f0- Δ f starting the operation and increasing the operating frequency of the system by a step α f until said operating frequency is frequency f0+ Δ f. Of course, the wireless charging system may also be at the frequency f0+ Δ f starts and decreases the operating frequency by a step α f until the operating frequency is frequency f0- Δ f. In addition, the wireless charging system can also use the frequency f0Starting to work, firstly increasing the working frequency by step length alpha f until the working frequency is the frequency f0+ Δ f, and decreasing the operating frequency by a step α f until the operating frequency is frequency f0- Δ f. Therefore, the wireless charging system may also perform frequency modulation in other manners, which are within the scope of the present invention and are not limited in this respect.
The frequency step α f may be determined according to at least one of device conditions, calculation accuracy, and required time. It should be noted that when the compensation capacitor C is used1And the compensation inductance L1Is unknown, i.e. the design resonant frequency f0When unknown, the frequency range f can be determined from the possible valuesmin，fmax]。
S13, monitoring a real-time current value on the transmitting coil.
In specific implementation, each working frequency of the wireless charging system and the corresponding transmitting coil L are usedPThe current value is sent to the receiving end in a wireless communication mode so as to ensure that the receiving end is realTime-sampling the compensation inductance L1The current voltage value at both ends and the receiving coil LSCurrent value of the current.
Preferably, the step S13 may further include: correspondingly adjusting the transmitting coil L at each working frequency of the wireless charging systemPInput voltage at both ends and monitoring the transmitting coil LPThe real-time current value of (c) is unchanged. It should be noted that, in the preferred embodiment, the frequency may be sampled in real time at the receiving end to obtain each of the operating frequencies synchronously, and each of the operating frequencies may also be transmitted in real time through a wireless communication manner, which are within the protection scope of the present invention and are not limited herein.
In a preferred embodiment, at each of the operating frequencies, the output voltage of the full-bridge inverter circuit 2, i.e. the transmitting coil L, can be changed by adjusting the duty ratio of the bridge arm thereofPInput voltage V at both endsinSo that the transmitting coil LPThe value of the upper current remains unchanged.
In another preferred embodiment, at each of the operating frequencies, the input voltage V of the transmitting terminal can be adjusteddcTo achieve the aim of said transmitting coil LPInput voltage V at both endsinSo that the transmitting coil LPThe value of the upper current remains unchanged.
And S14, sampling the real-time voltage at two ends of the compensation inductor and the real-time current on the receiving coil.
Note that, when the full-bridge rectifier circuit 1 is short-circuited, the compensation capacitor C is provided1The voltage across and the compensation inductance L1The voltages across are equivalent and therefore the two are interchangeable.
And S15, identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and/or the real-time voltage at the two ends of the compensation inductor.
In a preferred embodiment, the step S15 includes:
s151, comparing the real-time current values on the receiving coil to obtain a minimum current value;
and S152, acquiring the current working frequency corresponding to the minimum current value, namely the resonant frequency of the compensation capacitor and the compensation inductor.
It will be understood that, in theory, the compensation capacitance C should be considered as1And the compensation inductance L1At resonance, flows through the receiving coil LSThe current value of (a) is zero; however, in practice, the receiving coil L is affected by frequency step, internal resistance of the device, and the likeSThe compensation capacitor C is usually defaulted to a minimum value or below a predetermined current threshold1And the compensation inductance L1Is near resonance. Therefore, in concrete implementation, the above preferred embodiment may further include:
s151', comparing the real-time current value on the receiving coil with a preset current threshold value;
s152', obtaining a current operating frequency corresponding to a current value lower than the current threshold, that is, a resonant frequency of the compensation capacitor and the compensation inductor.
The current threshold value can be set according to the calculation precision requirement and the sampling precision condition of the mutual inductance parameter.
Preferably, the wireless charging system may be configured to operate from the design resonant frequency f for reduced time0Starting operation of the receiving coil LSThe frequency direction of the reduced current is frequency-modulated. Referring to fig. 4, a graph of the current value of the receiving coil varying with the operating frequency of the wireless charging system is shown; when the wireless charging system is at the frequency f0Starting operation, when increasing the operating frequency, e.g. measuring the receiving coil LSIf the current above is increased, the increase is stopped and the frequency f is started0Reducing the operating frequency until the receiving coil L is measuredSOr a current value below the current threshold.
In another preferred embodiment, the step S15 further includes:
s151 ", comparing the phase relation between the real-time current on the receiving coil and the real-time voltage at the two ends of the compensation inductor;
and S152', acquiring the current working frequency when the phase relation is resistive, namely the resonant frequency of the compensation capacitor and the compensation inductor.
It should be noted that the compensation inductance L1Voltage at both ends and the receiving coil LSThe phase relationship of the current above is divided into three types: capacitive, resistive and inductive; when the receiving coil LSCurrent ratio of the compensating inductance L1The voltage at the two ends leads by 90 degrees, and the phase relation is capacitive; when the receiving coil LSCurrent ratio of the compensating inductance L1The voltages at the two ends lag by 90 degrees, and the phase relation is inductive; when the receiving coil LSCurrent on and the compensation inductance L1The voltages at the two ends are synchronous, and the phase relation is resistive. Therefore, by comparing the receiving coils LSCurrent on and the compensation inductance L1Judging whether the phase relation of the voltages at the two ends is resistive or not to judge the compensation capacitor C1And the compensation inductance L1Whether it is resonant. However, in specific implementation, since the value of the frequency step α f may be too large, it may not be possible to identify the frequency point when the phase relationship is resistive, and then two adjacent frequency points where the phase relationship has a jump, that is, two adjacent frequency points where the phase relationship is changed from capacitive to inductive or from inductive to capacitive, may be identified, and then both of the two adjacent frequency points may be used as the compensation capacitor C1And the compensation inductance L1The operating frequency at resonance.
In addition, other means for determining the compensation capacitance C1And the compensation inductance L1The method of whether to resonate is within the scope of the present invention, and is not particularly limited herein.
And S16, calculating to obtain the mutual inductance value of the wireless charging system according to the resonant frequency, the corresponding current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor.
Preferably, the mutual inductance value M of the wireless charging system may be calculated by the following formula:
Figure BDA0002855949160000101
wherein f is the resonant frequency of the compensation capacitor and the compensation inductor, IpAnd U is the current value of the transmitting coil corresponding to the resonance frequency, and is the current voltage value at two ends of the compensation inductor corresponding to the resonance frequency.
It should be noted that the voltage value or the current value described in this embodiment is preferably an effective value of the voltage or the current, and of course, in practical application, the average value, the amplitude, and the like of the voltage or the current may also be an equivalent value, and only mathematical transformation needs to be performed according to actual needs.
In the mutual inductance detection method for the wireless charging system provided by this embodiment, before power transmission of the wireless charging system, the full-bridge rectification circuit of the receiving end is in a short-circuit state, the wireless charging system is controlled to perform frequency conversion work within a preset frequency range, a resonance frequency point of a compensation capacitor and a compensation inductor of the receiving end is identified, and then a mutual inductance value of the wireless charging system is calculated by combining measured electrical parameters at the resonance frequency point, that is, a current value on the transmitting coil and current voltage values at two ends of the compensation inductor of the receiving end. Therefore, the embodiment of the invention can eliminate the engineering error of the compensation parameter of the receiving end and greatly improve the detection precision by obtaining the electrical parameter when the compensation inductance and the compensation capacitance of the receiving end resonate or approach to resonate to obtain a more accurate mutual inductance value.
Example two
Referring to fig. 5, a flowchart of a method of controlling wireless charging is shown, the method includes steps S21 and S22, which are as follows:
s21, acquiring mutual inductance parameters of the wireless charging system through a mutual inductance detection method of the wireless charging system.
Preferably, when the mutual inductance detection method of the wireless charging system is implemented, the implementation of steps S11 to S16 in the first embodiment may be correspondingly adopted, and therefore, the description of this embodiment is not repeated.
And S22, controlling the system parameters of the wireless charging system to be adjusted according to the mutual inductance parameters so as to improve the system performance.
The power transmission of the wireless charging system is to transfer energy through a pair of coupled transmitting coil and receiving coil. In practical application, a large gap exists between the transmitting coil and the receiving coil, and loose coupling is achieved. In order to ensure the functional implementation of the wireless charging system and improve the performance and reliability of the system, a system control scheme usually requires the addition of mutual inductance parameters.
According to the wireless charging control method provided by the embodiment, the accurate mutual inductance parameter of the wireless charging system is obtained and incorporated into the system control, so that the performance and stability of the system are greatly improved.
EXAMPLE III
Referring to fig. 6, there is shown a system configuration diagram of a mutual inductance detection system of a wireless charging system including a transmitting terminal including a transmitting coil L and a receiving terminalPThe receiving end comprises a receiving coil LSAnd a compensation capacitor C1And a compensation inductance L1And a full-bridge rectification circuit 1, the transmitting coil LPAnd the receiving coil LSPrimary and secondary windings of a loosely coupled transformer, i.e. a transmitter and a receiver of energy, respectively, the currents being IPAnd IS. The transmitting terminal further comprises a full-bridge inverter circuit 2, wherein the full-bridge rectifier circuit 1 is composed of four switching tubes QS1、QS2、QS3And QS4The inverter circuit 2 is composed of four switching tubes QP1、QP2、QP3And QP4The switch tube is connected in a bridge form, and specifically, the switch tube can be one of switch devices such as a mos tube and an insulated gate bipolar transistor. The above-mentionedThe full-bridge inverter circuit 2 is responsible for converting direct current into high-frequency power, and the full-bridge rectifier circuit 1 is responsible for rectifying the high-frequency power and simultaneously outputting current IoutCarrying out adjustment; the compensation inductance L1Is connected to the receiving coil LSAnd the compensation capacitor C1The input terminal of, the compensation inductance L1Is connected with a bridge arm central point of the full-bridge rectification circuit 1, and the compensation capacitor C1Is connected with the receiving coil LSAnd the other bridge arm center point of the full-bridge rectification circuit 1. The input current of the full-bridge rectification circuit 1 is IeAt a midpoint voltage of VeThen its equivalent resistance Re＝Ve/Ie。
The mutual inductance detection system 20 of the wireless charging system comprises a circuit control unit 21, a frequency control unit 22, a monitoring unit 23, a sampling unit 24, a frequency identification unit 25 and a calculation unit 26, and specifically comprises the following steps:
the circuit control unit 21 is configured to control the full-bridge rectification circuit to be in a short-circuit state.
Preferably, Q in the full-bridge rectification circuit 1S1And QS2On, or QS3And QS4When the full-bridge rectification circuit 1 is conducted, the midpoint voltage V of the full-bridge rectification circuit 1 iseIs 0, its equivalent resistance ReAlso 0.
The frequency control unit 22 is configured to control the wireless charging system to perform variable frequency operation within a preset frequency range.
Preferably, the predetermined frequency range is determined by the compensation capacitor C1And the compensation inductance L1The design resonant frequency of (1) is the center frequency. In particular, the design resonant frequency f0Can be based on the compensation capacitance C1And the compensation inductance L1Is determined by the following formula:
Figure BDA0002855949160000121
wherein l10For said compensation inductance L1Design value of c10For said compensation capacitor C1Design value of (c).
Therefore, the predetermined frequency range is [ f0-Δf，f0+Δf]The frequency error Δ f is determined by the compensation capacitor C1And the compensation inductance L1Is determined according to the error range which can exist in the practical engineering application.
The monitoring unit 23 is configured to monitor a real-time current value on the transmitting coil.
Preferably, the monitoring unit 23 comprises a regulating module 23a and a monitoring module 23 b;
the adjusting module 23a is configured to correspondingly adjust the transmitting coil L at each operating frequency of the wireless charging systemPThe input voltage across.
In a preferred embodiment, the adjusting module 23a is specifically configured to: and adjusting the duty ratio of a bridge arm of the full-bridge inverter circuit 2.
In another preferred embodiment, the adjusting module 23a is specifically configured to: and adjusting the input voltage of the transmitting terminal.
The monitoring module 23b is used for monitoring the transmitting coil LPThe real-time current value of (c) is unchanged.
The sampling unit 24 is configured to sample a real-time voltage across the compensation inductor and a real-time current on the receiving coil.
The frequency identification unit 25 is configured to identify the resonant frequency of the compensation capacitor and the compensation inductor according to a comparison and judgment of a real-time current on the receiving coil and/or a real-time voltage across the compensation inductor.
In specific implementation, the frequency identification unit 25 includes a comparison module 25a and a frequency acquisition module 25 b;
in a preferred embodiment, the comparing module 25a is configured to compare the real-time current value on the receiving coil to obtain a minimum current value; the frequency obtaining module 25b is configured to obtain a current working frequency corresponding to the minimum current value, which is the resonant frequency of the compensation capacitor and the compensation inductor.
It will be understood that, in theory, the compensation capacitance C should be considered as1And the compensation inductance L1At resonance, flows through the receiving coil LSThe current value of (a) is zero; however, in practice, the receiving coil L is affected by frequency step, internal resistance of the device, and the likeSThe compensation capacitor C is usually defaulted to a minimum value or below a predetermined current threshold1And the compensation inductance L1Is near resonance. Therefore, in concrete implementation, the above preferred embodiment may further include:
the comparison module 25a is configured to compare the real-time current value on the receiving coil with a preset current threshold; the frequency obtaining module 25b is configured to obtain a current working frequency corresponding to a current value lower than the current threshold, that is, a resonant frequency of the compensation capacitor and the compensation inductor.
Preferably, the wireless charging system may be configured to operate from the design resonant frequency f for reduced time0Starting operation of the receiving coil LSThe frequency direction of the reduced current is frequency-modulated. Referring to fig. 4, a graph of the current value of the receiving coil varying with the operating frequency of the wireless charging system is shown; when the wireless charging system is at the frequency f0Starting operation, when increasing the operating frequency, e.g. measuring the receiving coil LSIf the current above is increased, the increase is stopped and the frequency f is started0Reducing the operating frequency until the receiving coil L is measuredSOr a current value below the current threshold.
In another preferred embodiment, the comparing module 25a is configured to compare a phase relationship between a real-time current on the receiving coil and a real-time voltage across the compensation inductor; the frequency obtaining module 25b is configured to obtain a current working frequency when the phase relationship is resistive, that is, a resonant frequency of the compensation capacitor and the compensation inductor.
The calculating unit 26 is configured to calculate a mutual inductance value of the wireless charging system according to the resonant frequency, a current value on the corresponding transmitting coil, and a current voltage value at two ends of the compensation inductor.
Preferably, the calculation unit 26 may perform the following calculation:
Figure BDA0002855949160000141
wherein f is the resonant frequency of the compensation capacitor and the compensation inductor, IpAnd U is the current value of the transmitting coil corresponding to the resonance frequency, and is the current voltage value at two ends of the compensation inductor corresponding to the resonance frequency.
It should be noted that, when the circuit control unit 21, the frequency control unit 22, the monitoring unit 23, the sampling unit 24, the frequency identification unit 25 and the calculating unit 26 are implemented, the implementation of steps S11 to S16 of the mutual inductance detection method of the wireless charging system provided in the first embodiment may be correspondingly adopted, and therefore, the description of this embodiment is not repeated.
Example four
Referring to fig. 7, it shows a system configuration diagram of a wireless charging control system, which includes a mutual inductance detection system 20 and a parameter control unit 30 of the wireless charging system shown in the third embodiment, specifically:
and the mutual inductance detection system 20 of the wireless charging system is used for acquiring mutual inductance parameters of the wireless charging system.
The parameter control unit 30 is configured to control a system parameter of the wireless charging system to adjust according to the mutual inductance parameter, so as to improve system performance.
It should be noted that the wireless charging control system and the wireless charging control method provided in this embodiment belong to the same concept, and specific implementation processes thereof are described in the method embodiments and are not described herein again.
In summary, according to the mutual inductance detection method, the control method and the corresponding system of the wireless charging system provided by the present invention, before the power transmission of the wireless charging system, the full-bridge rectification circuit of the receiving end is in a short-circuit state, the wireless charging system is controlled to start at a frequency conversion within a preset frequency range, the resonant frequency point of the compensation capacitor and the compensation inductor of the receiving end is identified, and then the mutual inductance value of the wireless charging system is calculated by combining the measured electrical parameter at the resonant frequency point, that is, the current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor of the receiving end, so that the control system controls the system parameter of the wireless charging system to adjust according to the mutual inductance value. Therefore, the embodiment of the invention obtains a relatively accurate mutual inductance value by obtaining the electrical parameters when the compensation inductance and the compensation capacitance of the receiving end resonate or approach to resonate, can eliminate the engineering error of the compensation parameters of the receiving end, and greatly improves the detection precision; and the accurate mutual inductance value is incorporated into the system control, so that the performance and the stability of the system are greatly improved.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes in form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a computer-readable storage medium, and when executed, can include the processes of the embodiments of the methods described above. The storage medium may be a magnetic disk, an optical disk, a Read-Only Memory (ROM), a Random Access Memory (RAM), or the like.

Claims (12)

1. The mutual inductance detection method of the wireless charging system is characterized in that the wireless charging system comprises a transmitting end and a receiving end, the transmitting end comprises a transmitting coil, and the receiving end comprises a receiving coil, a compensation capacitor, a compensation inductor and a full-bridge rectifying circuit, wherein the output end of the receiving coil is connected to the input end of the full-bridge rectifying circuit through the compensation inductor, the input end of the compensation capacitor is connected with the input end of the compensation inductor, and the output end of the compensation capacitor is connected with the output end of the receiving coil and the input end of the full-bridge rectifying circuit; the mutual inductance detection method comprises the following steps:
controlling the full-bridge rectifying circuit to be in a short-circuit state;
controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range;
monitoring a real-time current value on the transmitting coil;
sampling real-time voltage at two ends of the compensation inductor and real-time current on the receiving coil;
identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and/or the real-time voltage at two ends of the compensation inductor;
and calculating to obtain a mutual inductance value of the wireless charging system according to the resonance frequency, the corresponding current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor.
2. The mutual inductance detection method of a wireless charging system according to claim 1, wherein the monitoring of the real-time current value on the transmitting coil further comprises:
and under each working frequency of the wireless charging system, correspondingly adjusting the input voltage at two ends of the transmitting coil, and monitoring the real-time current value on the transmitting coil to be unchanged.
3. The mutual inductance detection method of the wireless charging system according to claim 1 or 2, wherein the identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil is specifically:
comparing the real-time current values on the receiving coils to obtain a minimum current value;
and acquiring the current working frequency corresponding to the minimum current value, namely the resonance frequency of the compensation capacitor and the compensation inductor.
4. The mutual inductance detection method of the wireless charging system according to claim 1 or 2, wherein the identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and the real-time voltage across the compensation inductor comprises:
comparing the phase relationship between the real-time current on the receiving coil and the real-time voltage at the two ends of the compensation inductor;
and acquiring the phase relation as the current working frequency when the resistance is adopted, namely the resonance frequency of the compensation capacitor and the compensation inductor.
5. The mutual inductance detection method of a wireless charging system according to claim 1, wherein the predetermined frequency range is centered at a designed resonance frequency of the compensation capacitor and the compensation inductor.
6. The mutual inductance detection method of the wireless charging system according to claim 1, wherein the mutual inductance value M of the wireless charging system is calculated by the following formula:
Figure FDA0002855949150000021
wherein f is the resonant frequency of the compensation capacitor and the compensation inductor, IpAnd U is the current value of the transmitting coil corresponding to the resonance frequency, and is the current voltage value at two ends of the compensation inductor corresponding to the resonance frequency.
7. A wireless charging control method, the method comprising:
acquiring mutual inductance parameters of the wireless charging system by using the mutual inductance detection method of the wireless charging system according to any one of claims 1 to 6;
and controlling system parameters of the wireless charging system to be adjusted according to the mutual inductance parameters so as to improve the system performance.
8. The mutual inductance detection system of the wireless charging system is characterized by comprising a transmitting end and a receiving end, wherein the transmitting end comprises a transmitting coil, and the receiving end comprises a receiving coil, a compensation capacitor, a compensation inductor and a full-bridge rectifying circuit; mutual inductance detection system includes circuit control unit, frequency control unit, monitoring unit, sampling unit, frequency identification unit, and the computational unit specifically is:
the circuit control unit is used for controlling the full-bridge rectifying circuit to be in a short-circuit state;
the frequency control unit is used for controlling the wireless charging system to work in a frequency conversion mode within a preset frequency range;
the monitoring unit is used for monitoring a real-time current value on the transmitting coil;
the sampling unit is used for sampling the real-time voltage at two ends of the compensation inductor and the real-time current on the receiving coil;
the frequency identification unit is used for identifying the resonance frequency of the compensation capacitor and the compensation inductor according to the comparison and judgment of the real-time current on the receiving coil and/or the real-time voltage at the two ends of the compensation inductor;
and the calculating unit is used for calculating to obtain a mutual inductance value of the wireless charging system according to the resonant frequency, the corresponding current value on the transmitting coil and the current voltage values at the two ends of the compensation inductor.
9. The mutual inductance detection system of the wireless charging system according to claim 8, wherein the monitoring unit comprises a regulating module and a monitoring module, and specifically comprises:
the adjusting module is used for correspondingly adjusting the input voltage at two ends of the transmitting coil under each working frequency of the wireless charging system;
and the monitoring module is used for monitoring the real-time current value on the transmitting coil to be unchanged.
10. The mutual inductance detection system of the wireless charging system according to claim 8 or 9, wherein the frequency identification unit includes a comparison module and a frequency acquisition module, and specifically:
the comparison module is used for comparing the real-time current value on the receiving coil to obtain the minimum current value;
the frequency obtaining module is configured to obtain a current working frequency corresponding to the minimum current value, which is a resonant frequency of the compensation capacitor and the compensation inductor.
11. The mutual inductance detection system of the wireless charging system according to claim 8 or 9, wherein the frequency identification unit includes a comparison module and a frequency acquisition module, and specifically:
the comparison module is used for comparing the phase relation between the real-time current on the receiving coil and the real-time voltage at the two ends of the compensation inductor;
the frequency obtaining module is configured to obtain a current working frequency when the phase relationship is resistive, that is, a resonant frequency of the compensation capacitor and the compensation inductor.
12. A wireless charging control system, characterized in that the control system comprises the mutual inductance detection system and the parameter control unit of the wireless charging system according to any one of claims 8 to 11;
the parameter control unit is used for controlling system parameters of the wireless charging system to be adjusted according to mutual inductance parameters acquired by the mutual inductance detection system of the wireless charging system so as to improve system performance.
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