CN115276261A - Control method of wireless charging impedance matching system - Google Patents
Control method of wireless charging impedance matching system Download PDFInfo
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- CN115276261A CN115276261A CN202211172382.7A CN202211172382A CN115276261A CN 115276261 A CN115276261 A CN 115276261A CN 202211172382 A CN202211172382 A CN 202211172382A CN 115276261 A CN115276261 A CN 115276261A
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- 239000003990 capacitor Substances 0.000 claims abstract description 21
- 238000001514 detection method Methods 0.000 claims abstract description 4
- 230000001939 inductive effect Effects 0.000 claims abstract 4
- 230000005540 biological transmission Effects 0.000 claims description 9
- 238000004364 calculation method Methods 0.000 claims description 6
- 230000005611 electricity Effects 0.000 claims 1
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- 238000010586 diagram Methods 0.000 description 4
- 230000005669 field effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000004804 winding Methods 0.000 description 2
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- 230000005674 electromagnetic induction Effects 0.000 description 1
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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
-
- 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
-
- 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
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- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
- H03H11/00—Networks using active elements
- H03H11/02—Multiple-port networks
- H03H11/28—Impedance matching networks
- H03H11/30—Automatic matching of source impedance to load impedance
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Computer Networks & Wireless Communication (AREA)
- Control Of Electrical Variables (AREA)
Abstract
The invention discloses a control method of a wireless charging impedance matching system, wherein the wireless charging impedance matching system is composed of a real part matching part and an imaginary part matching part of a load. The method comprises the following steps: obtaining the input impedance angle of the secondary loop by using the detection moduleθ Z If the value is 0, the compensation is finished; if not, determining inductive compensation or capacitive compensation as input of compensation characteristic judgment, calculating a matching capacitance value, and then determining a switching serial number and a compensation capacitance value of the switched capacitor bank; then the switch is switched on or off by combining the switch serial number obtained by the system controller; obtaining a new secondary side loop impedance angle, and then judging the compensation characteristic until the impedance angle is 0 and the closed-loop control of load imaginary part matching is finished;at the same time, the matching impedance of the pure resistance matching moduleR b Matching impedance with module for calculating matching impedanceR a And (4) through a subtracter, if the difference is not 0, continuously adjusting the duty ratio until the difference is 0, outputting the optimal impedance, and finishing the real part matching.
Description
Technical Field
The invention belongs to the field of compensation parameter design and efficiency optimization of a wireless power transmission system, and relates to a control method of a wireless charging impedance matching system.
Background
At present, most of impedance matching technologies for wireless charging at home and abroad relate to adjustment of an imaginary part of a load, but few documents are related to simultaneous matching of the imaginary part and a real part of the load, and a wireless charging adaptive impedance matching system and method disclosed in a published document (CN 108539874B) detects input impedance of a transmitting end and a mutual inductance between the transmitting end and a receiving end by using a detection module, determines the type of an impedance matching network and values of components in the impedance matching network according to the input impedance of the transmitting end and the mutual inductance between the transmitting end and the receiving end, and then builds a corresponding impedance matching network, so that the power amplifier can normally output power. The impedance matching method improves the load matching precision of the system to a certain extent, but still has the following problems: one is that two transmitting terminals are provided, namely one more coil is provided than each other, however, mutual inductance exists between the coils, but leakage inductance also exists to a certain extent, and the transmission efficiency of the system is reduced; secondly, the number of compensation units is large, and the number of switches in each dynamic compensation unit is too large, so that the switching loss is increased, and the control flow and the calculation of the matching capacitor are complex. Therefore, it is necessary to improve the dynamic compensation unit and improve the control flow of the system without affecting the transmission efficiency.
Disclosure of Invention
The invention mainly aims to provide a control method of a wireless charging impedance matching system, which is mainly innovated in closed-loop control of load imaginary part matching and a calculation method of matching capacitance, and aims to solve the problem that the existing resonant frequency deviates from the original inherent resonant point due to impedance mismatch in the charging process of the wireless charging system, so that the transmission efficiency of the system is reduced.
The purpose of the invention is realized by the following technical scheme: the invention provides a control method of a wireless charging impedance matching system, which comprises a Boost-Buck converter and a switched capacitor bank unit, wherein the switched capacitor bank unit is formed by connecting N branches in parallel, and each branch is formed by connecting an MOSFET (metal-oxide-semiconductor field effect transistor) tube and a capacitor in series.
The Boost-Buck converter is formed by cascading a Boost converter and a Buck converter, and the duty ratios of the Boost converter and the Buck converter are d 1 And d 2 . According to the working modes of the Boost-Buck converter,
，
，
，
let d = d 1 =d 2 (d is more than 0 and less than 1), the relation between the equivalent impedance of the Boost-Buck converter and the load impedance can be obtained through the formula
The formula shows that the Boost-Buck converter can realize wide-range adjustment of the resistance. The input impedance of the rectifier has a relation with the load impedance
Therefore, the relationship between the input impedance at the two ends ab and the duty ratio of the converter can be obtained as follows
。
The switch capacitor bank unit is formed by connecting N branches in parallel, each branch consists of an MOSFET (metal oxide semiconductor field effect transistor) tube and a capacitor, and then a dynamic capacitor bank is formed and can be used according to the requirement of a systemThe capacitor is used for switching on or off the MOSFET tube of the capacitor bank to realize dynamic tuning. As shown in FIG. 3, a method for switching a switched capacitor bank is first to detect the voltage across the secondary winding by a voltage sensorU 0 And a current sensor for detecting the secondary loop currentI 0 Then obtain the equivalent impedance of the secondary sideZ L Phase angle between voltage and currentθ Z And compensation capacitance of the systemC s 。
The impedance matching method is suitable for pure resistance as well as resistance-inductance load and resistance-capacitance load.
Drawings
Fig. 1 is a diagram of impedance matching for a wireless charging system;
FIG. 2 is an equivalent diagram of a wireless power transmission system;
fig. 3 is a detailed flowchart of the dynamic impedance matching method.
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
As shown in fig. 1, the rectifying and voltage-stabilizing system uses an uncontrolled full-bridge rectification and Boost-Buck conversion structure. The rectification circuit is a full-bridge uncontrollable rectification circuit formed by a voltage stabilizing diode, the output end of the rectification circuit is connected with a low-pass filter circuit, and the filter circuit is connected with the input end of the Boost-Buck converter; the Boost-Buck converter is formed by cascading a Boost circuit and a Buck circuit, wherein the output end of the converter is connected with a low-pass filter circuit and then connected with a load to charge the low-pass filter circuit. For convenience of research, the duty ratio of the converter is unified into d. When the load is pure resistance impedance, the working principle of the Boost-Buck Buck-Boost converter can be obtained
And the equivalent input impedance of the rectifier and the equivalent input impedance of the buck-boost converter meet
The relationship between duty ratio and load can be obtained by the above formula
According to the formula, the duty ratio d of the signal switching tube is adjusted to enable the load to be loaded
I.e. an optimal load is reached. When the load is non-pure resistance impedance, the matching can be carried out according to the next section of the switching switch capacitor bank.
The description is made with reference to fig. 2, which is an equivalent circuit diagram of a wireless power transmission system of an inverter and a converter, and a compensation inductor is connected with the equivalent circuit diagramL 1 And a compensation capacitorC p The formed compensation network is connected with a transmitting end, the transmitting end is connected with a receiving end through an electromagnetic induction principle, and then connected with a secondary side compensation capacitorC s Impedance in the figureZ L Is the equivalent impedance of the rectifier back end. According to kirchhoff's law, the transmission efficiency of the system can be obtained
If the wireless charging system is to achieve the maximum efficiency, the method includes the steps of
To obtain the optimum load
. Input impedance of secondary side
Having an impedance angle of
When the impedance angle is zero, the secondary loop reaches resonance, and the ideal compensation capacitance value is
When the impedance angle is zero, the secondary loop reaches resonance, and the ideal compensation capacitance value is
。
As shown in FIG. 3, which is a detailed flowchart of the dynamic impedance matching method, first, the voltage at the two ends of the secondary winding is detectedU 0 And secondary side loop currentI 0 Then, the input impedance of the secondary loop is obtainedZ s And angle of input impedanceθ Z . If the impedance angle is 0, no adjustment is necessary. Otherwise, if the voltage leads the current, the resistive-inductive load compensation is performedC L (ii) a If the voltage lags the current, then the RC load compensation is performedC C . Then according toC s /βC s (beta is more than 0 and less than 1, beta =1/n, n is an integer more than 1) to obtain the number m of the branch circuits required by the switched capacitor bank, and the capacitance value of each branch circuit is 1/m,2/m,3/m, …, a/m, b/m and n/m timesC s Wherein (b epsilon [1,a)]) The sum of them beingC s Then determining the switch serial number, the corresponding compensation capacitance value and each conducting switch signal to obtain a new secondary side loop impedance angle
If not, returning to the step (2); otherwise, the load imaginary part is matched with the closed-loop control and is ended; at the same time, the matching impedance of the pure resistance matching moduleR b Matching impedance with module for calculating matching impedanceR a Obtaining a difference value through a subtracter, if the difference value is not 0, returning to the step (5), and adjusting the duty ratio d; otherwise, if the difference is 0, the optimal impedance is output
And matching of the real part of the load is finished. From this, a wireless charging impedance matching system control method ends.
Claims (5)
1. A control method of a wireless charging impedance matching system is characterized in that the impedance matching system consists of load real part impedance matching and imaginary part impedance matching, the load real part impedance matching and the imaginary part impedance matching are respectively carried out by regulating the duty ratio by a Boost-Buck converter and switching on or off a switch capacitor group to realize the optimal impedance matching of a load, the load real part impedance matching and the load imaginary part impedance matching are not influenced by each other and are carried out simultaneously;
the method comprises the following steps: the matching method is carried out by two routes together;
load imaginary matched closed loop control route: firstly, the secondary side coil voltage of the wireless charging system is obtained through a detection moduleU 0 And secondary side loop currentI 0 Further obtain the secondary input impedanceZ s And angle of input impedanceθ Z If the impedance angle is 0, the matching is finished; otherwise, the system judges the compensation characteristic, if the voltage leads the current, the system carries out the inductive compensation and calculates the inductive capacitance
If the voltage lags the current, the capacitive compensation is performed and the capacitive capacitance is calculated
(ii) a Selecting a capacitor according to the calculated capacitance value to obtain a switch serial number and a compensation capacitance value, converting the switch serial number into binary codes through a system controller to control the on and off of the switch, and continuing to judge the compensation characteristic until the new impedance angle is 0 if the obtained new impedance angle is not 0;
load real part matching route: the pure resistance matching module can obtain the relation between the equivalent impedance of the converter and the load impedance according to the working mode of the Boost-Buck converter
On the other hand, the relation between the input equivalent impedance of the rectifier and the impedance of the Boost-Buck converter
Synthesizing the relationship between the input equivalent impedance of the two-way available rectifier, the load impedance and the duty ratio of the converter
The duty ratio can be adjusted to matchImpedance (L)R b (ii) a The calculation matching module obtains a system efficiency relation by establishing an equivalent model of the wireless transmission system, obtains a maximum value according to the partial derivative, and obtains a corresponding matching impedanceR a Real part matching technique.
2. The method of claim 1, wherein the method comprises: in the impedance matching method, the switch capacitor group consists of n branches, and each branch is formed by connecting a capacitor and a switch tube in series.
3. The method of claim 1, wherein the method comprises: the computing method of the imaginary part impedance matching closed-loop control compensation capacitor comprises the following steps: determination of the secondary input impedance by means of a detection module for the imaginary part and using kirchhoff's voltage law
And secondary input impedance angle
If the impedance angle is 0, finishing the compensation; otherwise, the impedance angle is used as the input of the judgment of the compensation characteristic, if the voltage leads the current, the system carries out the inductive compensation
If the voltage lags the current, the system performs capacitive compensation
According toC s /βC s (beta is more than 0 and less than 1, beta =1/n, n is an integer more than 1) to obtain the number m of the branch circuits required by the switched capacitor bank, and the capacitance value of each branch circuit is 1/m,2/m,3/m, …, a/m, b/m and n/m timesC s Wherein (b E [1,a)]) The sum of them beingC s (ii) a The system controller will switch the serial numberS 1 、S 2 、S 3 、…、S n A new impedance angle obtained by converting the binary code into a control signal for turning on or off the switch
If the impedance angle is not 0, the compensation characteristic is continuously judged until the impedance angle is 0.
4. The method of claim 1, wherein the method comprises: the real part impedance matching method consists of a pure resistance module and a calculation matching impedance module; the pure resistance module is formed by the relation between the equivalent impedance of the Boost-Buck converter and the load impedance
The input impedance of the rectifier is related to the impedance of the converter
Therefore, the relationship between the input impedance at the two ends of the rectifier input and the duty ratio of the converter is obtained as follows
The formula can show that the matched impedance can be obtained by adjusting the duty ratioR b (ii) a The calculation matching module is used for establishing an equivalent wireless charging system equation set
WhereinU in 、I 1 Respectively the output voltage and the output current of the high frequency inverter,R p 、R s 、Z L respectively the internal resistance of the transmitting coil, the internal resistance of the receiving coil and the system load;L s 、L p m is the mutual inductance coefficient of the receiving coil, the transmitting coil and the primary side and the secondary side respectively;L 1 、C p 、C s for compensating the electricity for the primary sideThe inductance, the compensation capacitance and the secondary side compensation capacitance, and the impedance of each component can be expressed as
、
、
、
、
、
W is the angular frequency of the system, and the system efficiency relation is obtained when the system resonates
Let us order
To obtain impedance matching
A relation to maximum transmission efficiency; the difference value is obtained by the subtracter, and if the difference value is not 0, the duty ratio is continuously adjusted; otherwise, if the difference is 0, the optimal impedance is output
。
5. The method according to claim 1, wherein the dynamic impedance matching method is applied to a system with a purely resistive load and a non-purely resistive load.
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116455357A (en) * | 2023-06-13 | 2023-07-18 | 深圳市恒运昌真空技术有限公司 | Active impedance matching box based on Boost circuit and adjusting method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN109391044A (en) * | 2018-11-14 | 2019-02-26 | 中国矿业大学 | A kind of efficient pressure stabilizing complex control system of inductive electric energy transmission system and method |
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116455357A (en) * | 2023-06-13 | 2023-07-18 | 深圳市恒运昌真空技术有限公司 | Active impedance matching box based on Boost circuit and adjusting method thereof |
| CN116455357B (en) * | 2023-06-13 | 2023-09-05 | 深圳市恒运昌真空技术有限公司 | Active impedance matching box based on Boost circuit and adjusting method thereof |
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Application publication date: 20221101 |