CN112886815A - Cascaded boost-buck converter for impedance matching of wireless power transmission system and control method thereof - Google Patents
Cascaded boost-buck converter for impedance matching of wireless power transmission system and control method thereof Download PDFInfo
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- CN112886815A CN112886815A CN202110033928.XA CN202110033928A CN112886815A CN 112886815 A CN112886815 A CN 112886815A CN 202110033928 A CN202110033928 A CN 202110033928A CN 112886815 A CN112886815 A CN 112886815A
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- 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
- 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
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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
- H02J50/70—Circuit arrangements or systems for wireless supply or distribution of electric power involving the reduction of electric, magnetic or electromagnetic leakage fields
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from ac mains by converters
- H02J7/04—Regulation of charging current or voltage
- H02J7/06—Regulation of charging current or voltage using discharge tubes or semiconductor devices
Abstract
The application discloses a cascade boost-buck converter for impedance matching of a wireless power transmission system and a control method thereof, and relates to the field of circuit control. The cascade Boost-Buck converter for impedance matching of the wireless power transmission system comprises a Boost converter, a Buck converter, a switching signal control circuit, an input current detection circuit, an input voltage detection circuit, a load current detection circuit and a load voltage detection circuit; the first switching signal control circuit outputs a first PWM signal according to the input current, the input voltage and the optimal load value of the wireless power transmission system so as to control a switching device in the Boost converter; the second switching signal control circuit outputs a second PWM signal according to the load current and the load voltage so as to control a switching device in the Buck converter; the problem that the transmission efficiency of the existing wireless power transmission system is low is solved; the effect of improving the transmission efficiency of the wireless power transmission system is achieved.
Description
Technical Field
The application relates to the field of circuit control, in particular to a cascade boost-buck converter for impedance matching of a wireless power transmission system and a control method thereof.
Background
With the continuous development of the charging technology of electric vehicles, the Magnetic Coupling Resonance type wireless Power transmission technology (MCR-WPT) receives more and more attention and research at home and abroad. The system transmission efficiency of the MCR-WPT system is influenced by the change of the transmission distance of a system coil or the change of battery impedance of an electric automobile battery in the charging and discharging processes. If the MCR-WPT system can maintain the impedance matching state, the transmission efficiency of the MCR-WPT system will be greatly improved.
At present, impedance matching research methods for MCR-WPT systems are the most common methods, namely a variable coupling coefficient matching method and an embedded capacitor array matching method. In the matching method with variable coupling coefficient, as shown in fig. 1, the two-coil structure of the resonance transmission system is modified into the four-coil structure, so as to implement impedance matching between the power end and the load end, but the loss increases with the increase of the number of coils, and the transmission efficiency of the whole system is affected. In the matching method of the embedded capacitor array, a matching network formed by the capacitor array is embedded between a high-frequency power supply and a transmitting coil, and the impedance matching of a system is realized by utilizing the maximum transmission power theory.
Disclosure of Invention
The present application is directed to provide a cascaded boost-buck converter for impedance matching of a wireless power transmission system and a control method thereof, so as to implement dynamic impedance matching of the wireless power transmission system and improve transmission efficiency of the wireless power transmission system.
In order to achieve the purpose, the application provides the following technical scheme:
in a first aspect, an embodiment of the present application provides a cascade Boost-Buck converter for impedance matching of a wireless power transmission system, including a Boost converter, a Buck converter, a first switching signal control circuit, a second switching signal control circuit, an input current detection circuit, an input voltage detection circuit, a load current detection circuit, and a load voltage detection circuit;
the Boost converter is connected with the wireless power transmission system, the Buck converter is cascaded with the Boost converter, and the Buck converter is connected with the variable load;
the input current detection circuit is used for detecting the input current of the input end of the Boost converter;
the input voltage detection current is used for detecting the input voltage of the input end of the Boost converter;
the wireless power transmission system comprises a first switching signal control circuit, a second switching signal control circuit and a wireless power transmission system, wherein the first switching signal control circuit is used for outputting a first PWM signal according to input current, input voltage and an optimal load value of the wireless power transmission system, and the first PWM signal is used for controlling a switching device in a Boost converter;
a load current detection circuit for detecting a load current;
a load voltage detection circuit for detecting a load voltage;
and the second switching signal control circuit is used for outputting a second PWM signal according to the load current and the load voltage, and the second PWM signal is used for controlling a switching device in the Buck converter.
Furthermore, the first switch signal control circuit comprises a first amplifying circuit, a first difference circuit, a first PI regulating circuit, a first fundamental wave circuit and a first comparison circuit;
the first amplifying circuit is used for receiving the input current and amplifying the input current by a first preset multiple; the first preset multiple is determined according to the optimal load value of the wireless power transmission system;
the first amplifying circuit is connected with the first difference circuit, the first difference circuit is connected with the first PI regulating circuit, and the first PI regulating circuit and the first fundamental wave circuit are respectively connected with the first comparing circuit;
the first difference circuit is used for acquiring a first difference signal of the amplified input current and the amplified input voltage;
the first PI adjusting circuit is used for receiving and adjusting the first difference signal;
and the first comparison circuit is used for outputting a first PWM signal for controlling a switching device in the Boost converter according to the output signal of the first PI regulating circuit and the output signal of the first fundamental wave circuit.
Furthermore, the second switch signal control circuit comprises a second amplifying circuit, a second difference circuit, a second PI regulating circuit, a second fundamental wave circuit and a second comparison circuit;
the second amplifying circuit is used for receiving the load current and amplifying the load current by a second preset multiple; the second predetermined multiple is greater than the load value of t times; the load value is determined according to the load voltage and the load current;
the second amplifying circuit is connected with a second difference circuit, the second difference circuit is connected with a second PI regulating circuit, and the second regulating circuit and the second fundamental wave circuit are respectively connected with a second comparison circuit;
the second difference circuit is used for acquiring a second difference value of the amplified load current and the amplified load voltage;
the second PI adjusting circuit is used for receiving and adjusting the second difference signal;
and the second comparison circuit is used for outputting a second PWM signal for controlling a switching device in the Boost converter according to the output signal of the second PI regulating circuit and the output signal of the second fundamental wave circuit.
Further, t is more than or equal to 3.
In a second aspect, the present invention provides a method for controlling a cascaded boost-buck converter for impedance matching of a wireless power transmission system, where the method is applied to the cascaded boost-buck converter for impedance matching of the wireless power transmission system as shown in the first aspect, and the method includes:
the method comprises the steps that input voltage provided by a wireless power transmission system is received through a Boost converter, load voltage is output through a Buck converter cascaded with the Boost converter, and the load voltage is used for charging a variable load;
acquiring input current through an input current electrical measuring circuit, and acquiring input voltage through an input voltage detecting circuit;
acquiring load current through a load current detection circuit, and acquiring load voltage through a load voltage detection circuit;
outputting a first PWM signal through a first switching signal control circuit according to input current, input voltage and an optimal load value of a wireless power transmission system, wherein the first PWM signal is used for controlling a switching device in a Boost converter;
and outputting a second PWM signal through a second switching signal control circuit according to the load current and the load voltage, wherein the second PWM signal is used for controlling a switching device in the Buck converter.
Furthermore, the first switch signal control circuit comprises a first amplifying circuit, a first difference circuit, a first PI regulating circuit, a first fundamental wave circuit and a first comparison circuit;
outputting a first PWM signal according to an input current, an input voltage and an optimal load value of a wireless power transmission system through a first switching signal control circuit, comprising:
receiving input current through a first amplifying circuit, and amplifying the input current by a first preset multiple; the first preset multiple is determined according to the optimal load value of the wireless power transmission system;
acquiring a first difference signal of the amplified input current and the amplified input voltage through a first difference circuit;
receiving and adjusting the first difference signal through a first PI adjusting circuit;
and outputting a first PWM signal for controlling a switching device in the Boost converter through a first comparison circuit according to the output signal of the first PI regulating circuit and the output signal of the first fundamental wave circuit.
Furthermore, the second switch signal control circuit comprises a second amplifying circuit, a second difference circuit, a second PI regulating circuit, a second fundamental wave circuit and a second comparison circuit;
outputting a second PWM signal according to the load current and the load voltage through a second switching signal control circuit, comprising:
receiving the load current through a second amplifying circuit, and amplifying the load current by a second preset multiple; the second predetermined multiple is greater than the load value of t times; the load value is determined according to the load voltage and the load current;
acquiring a second difference signal of the amplified input current and the amplified input voltage through a second difference circuit;
receiving and adjusting a second difference signal through a second PI adjusting circuit;
and outputting a second PWM signal for controlling a switching device in the Boost converter through a second comparison circuit according to the output signal of the second PI regulating circuit and the output signal of the second fundamental wave circuit.
Further, t is more than or equal to 3.
The beneficial effect of this application lies in:
the input current, the input voltage, the load current and the load voltage are measured in real time, the input current and the input voltage are fed back to the first switching signal control circuit, the load current and the load voltage are fed back to the second switching signal control circuit, the first switching signal control circuit outputs a first PWM signal to adjust the conduction duty ratio of a switching device in the Boost converter, the second switching signal control circuit outputs a second PWM signal to adjust the conduction duty ratio of the switching device in the Buck converter, and the first switching signal control circuit and the second switching signal control circuit accurately adjust the input impedance to complete impedance matching of a power supply end and a load end; the problem that the transmission efficiency of the existing wireless power transmission system is low is solved; the effect of improving the transmission efficiency of the wireless power transmission system is achieved.
The foregoing is a summary of the present disclosure, and in order to provide a clear understanding of the technical solutions of the present disclosure and to be implemented in accordance with the present disclosure, the following is a detailed description of the preferred embodiments of the present disclosure with reference to the accompanying drawings.
Drawings
Fig. 1 is a schematic diagram of a conventional impedance matching network for a wireless power transmission system;
fig. 2 is a block diagram of a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present disclosure;
fig. 3 is a schematic diagram of a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present disclosure;
fig. 4 is a block diagram of a first switching signal control circuit according to an embodiment of the present disclosure;
fig. 5 is a block diagram of a second switching signal control circuit according to an embodiment of the present disclosure;
fig. 6 is a flowchart of a control method of a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present disclosure;
fig. 7 is a simulation diagram of the input current Iin and the input voltage Vin under the condition that the optimal load value provided by the embodiment of the present application is 50;
fig. 8 is a simulation diagram of the load voltage Vload under the condition that the optimal load value is 50 according to the embodiment of the present application;
fig. 9 is a simulation diagram of the input current Iin and the input voltage Vin under the condition that the optimal load value provided by the embodiment of the present application is 100.
Detailed Description
The technical solutions of the present application will be described clearly and completely with reference to the accompanying drawings, and it should be understood that the described embodiments are only some embodiments of the present application, but not all 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 application.
In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and do not indicate or imply that the device or element being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus, should not be construed as limiting the present application. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.
In the description of the present application, it is to be noted that, unless otherwise explicitly specified or limited, the terms "mounted," "connected," and "connected" are to be construed broadly, e.g., as meaning either a fixed connection, a removable connection, or an integral connection; can be mechanically or electrically connected; they may be connected directly or indirectly through intervening media, or they may be interconnected between two elements. The specific meaning of the above terms in the present application can be understood in a specific case by those of ordinary skill in the art.
In addition, the technical features mentioned in the different embodiments of the present application described below may be combined with each other as long as they do not conflict with each other.
Referring to fig. 2, a block diagram of a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present disclosure is shown.
The wireless power transmission system comprises a Boost converter 130, a Buck converter 140, a first switching signal control circuit 150, a second switching signal circuit 160, an input current detection circuit 270, an input voltage detection circuit 260, a load current detection circuit 370 and a load voltage detection circuit 360.
The Boost converter 130 is connected to a Wireless Power Transfer (WPT) system 110, the Buck converter 140 is cascaded with the Boost converter 130, and the Buck converter 140 is connected to the variable load 120.
During charging, the impedance of the variable load 120 may change.
The cascade Boost converter 130 and the Buck converter realize a DC-DC conversion function, and realize charging of the variable load 120.
The input current detection circuit 270 is used to detect an input current Iin at the input terminal of the Boost converter.
The input voltage detection circuit 260 is used for detecting an input voltage Vin at an input terminal of the Boost converter.
The first switching signal control circuit 150 is configured to output a first PWM signal according to the input current, the input voltage, and the optimal load value of the wireless power transmission system; the first PWM signal is used to control a switching device in the Boost converter.
The maximum transmission efficiency of the wireless power transmission system corresponds to an optimal load value, and the optimal load value corresponding to the wireless power transmission system can be determined according to the parameters of the wireless power transmission system.
And adjusting the conduction duty ratio of a switching device in the Boost converter through the first PWM signal.
The load current detection circuit 370 is configured to detect the load current Iload. The load voltage detection circuit 360 is used for detecting the load voltage Vload.
The second switching signal control circuit 160 is configured to output a second PWM signal according to the load current and the load voltage; the second PWM signal is used to control the switching devices in the Buck converter.
And adjusting the conduction duty ratio of a switching device in the Buck converter through the second PWM signal.
In the converter provided by the embodiment of the application, the input current, the input voltage, the load current and the load voltage are measured in real time, the input current and the input voltage are fed back to the first switching signal control circuit, the load current and the load voltage are fed back to the second switching signal control circuit, the first switching signal control circuit outputs the first PWM signal, the adjustment of the conduction duty ratio of a switching device in the Boost converter is realized, the second switching signal control circuit outputs the second PWM signal, the adjustment of the conduction duty ratio of the switching device in the Buck converter is realized, the adjustment of the input impedance is accurately realized through the first switching signal control circuit and the second switching signal control circuit, and the impedance matching of a power supply end and a load end is completed; the problem that the transmission efficiency of the existing wireless power transmission system is low is solved; the effect of improving the transmission efficiency of the wireless power transmission system is achieved.
Fig. 3 schematically illustrates a schematic diagram of a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present application.
The Boost converter is composed of a switching device Q1, an inductor L1, a capacitor C1 and a diode D1; the Buck converter is composed of a switching device Q2, an inductor L2, a capacitor C2 and a diode D2.
The conduction of the switching device Q1 is controlled by the first PWM signal pulse1, and the conduction of the switching device Q2 is controlled by the second PWM signal pulse 2.
As shown in fig. 4, the first switching signal control circuit includes a first amplifying circuit 210, a first difference circuit 220, a first PI adjusting circuit 230, a first fundamental wave circuit 240, and a first comparing circuit 250.
The first amplification circuit 210 receives the input current Iin output from the input current detection circuit 270 and amplifies the input current Iin by a first multiple Rin.
The first amplification factor Rin is determined according to an optimal load value of the wireless power transmission system.
The first amplifying circuit 210 is connected to the first difference circuit 220, the first difference circuit 220 is connected to the first PI regulator circuit 230, and the first PI regulator circuit 230 and the first fundamental wave circuit 240 are connected to the first comparator circuit 250, respectively.
The first difference circuit 220 is configured to obtain a first difference signal between the amplified input current (Rin × Iin) and the input voltage Vin.
The first PI adjustment circuit 230 is configured to receive and adjust the first difference signal.
The first fundamental wave circuit 240 is for providing a fundamental wave. Optionally, the fundamental wave is a triangular wave. The frequency and peak value of the fundamental wave are determined according to actual conditions.
The first comparison circuit 250 receives the output signal of the first PI regulation circuit 230 and the fundamental wave signal output by the first fundamental circuit 240, compares the output signal of the first PI regulation circuit 230 and the fundamental wave signal by the first comparison circuit 250, and outputs a first PWM signal pulse1 according to the comparison result.
As shown in fig. 5, the second switching signal control circuit includes a second amplifying circuit 310, a second difference circuit 320, a second PI adjusting circuit 330, a second fundamental wave circuit 340, and a second comparing circuit 350.
The second amplifying circuit 310 receives the load current Iload detected by the input load detecting circuit 360 and amplifies the load current Iload by a second multiple K.
The second amplification factor K is larger than the load value of t times, namely K is larger than t × Rload; the load value Rload is determined from the load voltage Vload and the load current Iload.
As can be seen from FIG. 3, the voltage at the end of the capacitor C2 is Vbf, and Vbf > Vin is indirectly set by setting the second amplification factor K, so as to balance the input and output power.
Optionally, t is more than or equal to 3.
The second amplifying circuit 310 is connected to the second difference circuit 320, the second difference circuit 320 is connected to the second PI adjusting circuit 330, and the second PI adjusting circuit 330 and the second fundamental wave circuit 340 are connected to the second comparing circuit 350, respectively.
The second difference circuit 320 is configured to obtain a second difference signal between the amplified input current (Rin × Iin) and the input voltage Vin.
The second PI regulation circuit 330 is configured to receive and regulate the second difference signal.
The second fundamental wave circuit 340 is for providing a fundamental wave. Optionally, the fundamental wave is a triangular wave. The frequency and peak value of the fundamental wave are determined according to actual conditions.
The second comparing circuit 350 receives the output signal of the second PI regulating circuit 330 and the fundamental wave signal output by the second fundamental circuit 340, compares the output signal of the second PI regulating circuit 330 with the fundamental wave signal by using the second comparing circuit 350, and outputs a second PWM signal pulse2 according to the comparison result.
As shown in fig. 3, the relationship between the voltage Vbf across the capacitor C1 and the input voltage Vin is:
d1 is the on duty cycle of the switching device Q1 in the Boost converter.
The relationship between the load voltage Vload and the voltage Vbf across the capacitor C1 is:
Vload＝D2×Vbf (2)
d2 is the on duty cycle of the switching device Q2 in the Buck converter.
The input resistance of the cascade boost-buck converter provided by the embodiment of the application is as follows:
pin is the product of the input voltage Vin and the input current Iin.
Substituting equation (1) into equation (3) yields the relationship between D1 and Vbf as:
rin is set as an optimal load value corresponding to the maximum transmission efficiency of the wireless power transmission system.
As can be seen from fig. 4, in the first switching signal control circuit, the first PI regulation circuit 230 may reduce an error between the input voltages Vin and Rin, so that the wireless power transmission system can operate in an optimal load state when the load changes.
As can be seen from fig. 5, in the second switching signal control circuit, the second PI regulation circuit 330 may enable the load current Iload to track the change of the load voltage Vload by a fixed ratio K, so as to reduce the voltage fluctuation corresponding to the load current Iload.
Referring to fig. 6, a flowchart of a control method for a cascaded boost-buck converter for impedance matching of a wireless power transmission system according to an embodiment of the present application is shown, where the method is applied to the cascaded boost-buck converter for impedance matching of a wireless power transmission system shown in fig. 2.
Step 601, receiving an input voltage provided by the wireless power transmission system through a Boost converter, and outputting a load voltage through a Buck converter cascaded with the Boost converter.
The load voltage is used to charge a variable load. During charging, the impedance of the variable load changes.
Step 602, obtaining an input current through an input current electrical measurement circuit, and obtaining an input voltage through an input voltage detection circuit.
It should be noted that step 602 and step 603 may be executed simultaneously, or step 603 is executed before step 602, which is not limited in this embodiment of the application.
And step 604, outputting a first PWM signal through the first switch signal control circuit according to the input current, the input voltage and the optimal load value of the wireless power transmission system.
The first PWM signal is used to control a switching device in the Boost converter.
The optimal load value of the wireless power transmission system is determined according to the parameters of the wireless power transmission system.
The second PWM signal is used to control the switching devices in the Buck converter.
It should be noted that, the step 604 and the step 605 may be executed simultaneously, or the step 605 is executed before the step 604, which is not limited in this application.
In an alternative embodiment based on the embodiment shown in fig. 6, the first switching signal control circuit includes a first amplifying circuit 210, a first difference circuit 220, a first PI regulating circuit 230, a first fundamental wave circuit 240, and a first comparing circuit 250, as shown in fig. 4.
The above step 604 can be implemented as follows:
step 6041, receive the input current through a first amplification circuit and amplify the input current by a first predetermined multiple.
The first predetermined multiple is determined according to an optimal load value of the wireless power transmission system.
Step 6042, obtain a first difference signal between the amplified input current and the amplified input voltage through a first differencing circuit.
Step 6043, the first difference signal is received and conditioned by the first PI conditioning circuit.
Step 6044, a first PWM signal for controlling a switching device in the Boost converter is output by the first comparison circuit according to the output signal of the first PI regulation circuit and the output signal of the first fundamental wave circuit.
The output signal of the first fundamental wave circuit is a fundamental wave signal. Optionally, the fundamental wave signal is a triangular wave signal.
The frequency and peak value of the fundamental wave signal are determined according to actual conditions.
The output signal of the first PI regulation circuit is compared with the fundamental wave signal by the first comparison circuit, and then the first PWM signal pulse1 is output according to the comparison result.
In an alternative embodiment based on the embodiment shown in fig. 6, the second switching signal control circuit includes a second amplifying circuit 310, a second difference circuit 320, a second PI regulating circuit 330, a second fundamental wave circuit 340, and a second comparing circuit 350, as shown in fig. 5.
The above step 605 can be implemented as follows:
outputting a second PWM signal according to the load current and the load voltage through a second switching signal control circuit, comprising:
step 6051, receive the load current through a second amplification circuit and amplify the load current by a second predetermined factor.
The second predetermined multiple is greater than the load value of t times; the load value is determined from the load voltage and the load current.
Optionally, t is more than or equal to 3.
Step 6052, a second difference signal of the amplified input current and the amplified input voltage is obtained through a second difference circuit.
Step 6053, receive and condition the second difference signal via the second PI regulation circuit.
In step 5054, a second PWM signal for controlling the switching device in the Boost converter is output through the second comparison circuit according to the output signal of the second PI regulation circuit and the output signal of the second fundamental wave circuit.
The output signal of the second fundamental wave circuit is a fundamental wave signal. Optionally, the fundamental wave signal is a triangular wave signal.
The frequency and peak value of the fundamental wave signal are determined according to actual conditions.
And comparing the output signal of the second PI regulating circuit with the fundamental wave signal through a second comparison circuit, and outputting a second PWM signal pulse1 according to the comparison result.
According to the control method of the cascade boost-buck converter for impedance matching of the wireless power transmission system, closed-loop feedback control is completed through the first switch signal control circuit and the second switch signal control circuit, dynamic impedance matching of the wireless power transmission system is achieved, the control method can be suitable for high frequency and low frequency, selection of a power supply, a coupling coil and a rectification circuit is not limited, and the application range is wider. In addition, when the input impedance is stabilized and the load is changed, the load voltage can be recovered to a relatively stable value in a short time, so that the voltage stability of the load end is better, and the effect of protecting the load is achieved.
In an example, a simulation experiment is performed on the cascaded boost-buck converter for impedance matching of the wireless power transmission system shown in fig. 2 to 5, and if the optimal load corresponding to the maximum transmission efficiency of the wireless power transmission system is set to 50 Ω, the optimal load value is 50. Fig. 7 shows a schematic diagram of the changes of the input current Iin and the input voltage Vin in this case, and the input voltage Vin jumps from 50V to 70V at 0.05 s. Fig. 8 shows a schematic diagram of the change of the load voltage Vload in this case.
As can be seen from FIG. 7, before the jump of the input voltage Vin, the value of Vin/Iin is 52.626 Ω, which is consistent with the set optimal load of 50 Ω; after the jump of the input voltage Vin, the value of Vin/Iin is 50.677 Ω, which is consistent with the set optimal load of 50 Ω; the effect that the wireless power transmission system is still enabled to operate in the optimal load state under the condition that the input voltage changes is achieved.
In the process of the simulation experiment, the load resistance is adjusted from 50 Ω to 10 Ω between 0.03s and 0.04s and between 0.06s and 0.08s, and the changes of the input voltage Vin and the input current Iin cannot be seen from fig. 7, so that the influence of the load change on the equivalent input resistance is eliminated.
As can be seen from fig. 8, the input voltage Vin jumps from 50V to 70V at 0.05s, and the change of the load voltage Vload is relatively small; the load resistance is adjusted from 50 omega to 10 omega between 0.03s and 0.04s, the load voltage Vload can respond in a very fast time in the time of the change of the load resistance and is adjusted to a relatively stable value, and the voltage stability at the load end is better.
In another example, a simulation experiment is performed on the cascaded boost-buck converter for impedance matching of the wireless power transmission system shown in fig. 2 to 5, and if the optimal load corresponding to the maximum transmission efficiency of the wireless power transmission system is set to 100 Ω, the optimal load value is 100. Fig. 9 shows a schematic diagram of changes of the input current Iin and the input voltage Vin in this case, and the input voltage Vin jumps from 50V to 70V at 0.05 s.
As can be seen from FIG. 9, before the jump of the input voltage Vin, the value of Vin/Iin is 106.281 Ω, which is consistent with the set optimal load of 100 Ω; after the input voltage Vin jumps, the value of Vin/Iin is 104.406 Ω, which is consistent with the set optimal load of 100 Ω; the effect that the wireless power transmission system is still enabled to operate in the optimal load state under the condition that the input voltage changes is achieved.
In the process of the simulation experiment, the load resistance is adjusted from 50 Ω to 10 Ω in 0.03s to 0.04s and 0.06s to 0.08s, and the changes of the input voltage Vin and the input current Iin cannot be seen from fig. 9, so that the influence of the load change on the equivalent input resistance is eliminated.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present application, and the description thereof is more specific and detailed, but not construed as limiting the claims. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the concept of the present application, which falls within the scope of protection of the present application. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (8)
1. A cascade Boost-Buck converter for impedance matching of a wireless power transmission system is characterized by comprising a Boost converter, a Buck converter, a first switching signal control circuit, a second switching signal control circuit, an input current detection circuit, an input voltage detection circuit, a load current detection circuit and a load voltage detection circuit;
the Boost converter is connected with a wireless power transmission system, the Buck converter is cascaded with the Boost converter, and the Buck converter is connected with a variable load;
the input current detection circuit is used for detecting the input current of the input end of the Boost converter;
the input voltage detection current is used for detecting the input voltage of the input end of the Boost converter;
the first switching signal control circuit is used for outputting a first PWM signal according to the input current, the input voltage and an optimal load value of a wireless power transmission system, and the first PWM signal is used for controlling a switching device in the Boost converter;
the load current detection circuit is used for detecting load current;
the load voltage detection circuit is used for detecting the load voltage;
and the second switching signal control circuit is used for outputting a second PWM signal according to the load current and the load voltage, and the second PWM signal is used for controlling a switching device in the Buck converter.
2. The cascaded boost-buck converter for impedance matching of a wireless power transfer system according to claim 1, wherein the first switching signal control circuit includes a first amplifying circuit, a first differentiating circuit, a first PI regulating circuit, a first fundamental wave circuit, a first comparing circuit;
the first amplifying circuit is used for receiving the input current and amplifying the input current by a first preset multiple; the first preset multiple is determined according to the optimal load value of the wireless power transmission system;
the first amplifying circuit is connected with the first difference circuit, the first difference circuit is connected with the first PI regulating circuit, and the first PI regulating circuit and the first fundamental wave circuit are respectively connected with the first comparing circuit;
the first difference circuit is used for acquiring a first difference signal of the amplified input current and the amplified input voltage;
the first PI adjusting circuit is used for receiving and adjusting the first difference signal;
and the first comparison circuit is used for outputting a first PWM signal for controlling a switching device in a Boost converter according to the output signal of the first PI regulating circuit and the output signal of the first fundamental wave circuit.
3. The cascaded boost-buck converter for impedance matching of a wireless power transfer system according to claim 1, wherein the second switching signal control circuit comprises a second amplifying circuit, a second differentiating circuit, a second PI regulating circuit, a second fundamental wave circuit, and a second comparing circuit;
the second amplifying circuit is used for receiving the load current and amplifying the load current by a second preset multiple; the second predetermined multiple is greater than the load value of t times; the load value is determined according to the load voltage and the load current;
the second amplifying circuit is connected with the second difference circuit, the second difference circuit is connected with the second PI regulating circuit, and the second regulating circuit and the second fundamental wave circuit are respectively connected with a second comparison circuit;
the second difference circuit is used for acquiring a second difference value between the amplified load current and the load voltage;
the second PI regulating circuit is used for receiving and regulating the second difference signal;
and the second comparison circuit is used for outputting a second PWM signal for controlling a switching device in the Boost converter according to the output signal of the second PI regulating circuit and the output signal of the second fundamental wave circuit.
4. The cascaded boost-buck converter for impedance matching of a wireless power transfer system according to claim 3, wherein t ≧ 3.
5. A control method of a cascaded boost-buck converter for impedance matching of a wireless power transmission system is applied to the cascaded boost-buck converter for impedance matching of the wireless power transmission system according to any one of claims 1 to 4, and the method comprises the following steps:
receiving input voltage provided by a wireless power transmission system through a Boost converter, and outputting load voltage through a Buck converter cascaded with the Boost converter, wherein the load voltage is used for charging a variable load;
acquiring input current through an input current electrical measuring circuit, and acquiring input voltage through an input voltage detecting circuit;
acquiring load current through a load current detection circuit, and acquiring load voltage through a load voltage detection circuit;
outputting a first PWM signal through a first switching signal control circuit according to the input current, the input voltage and an optimal load value of a wireless power transmission system, wherein the first PWM signal is used for controlling a switching device in the Boost converter;
and outputting a second PWM signal through a second switching signal control circuit according to the load current and the load voltage, wherein the second PWM signal is used for controlling a switching device in the Buck converter.
6. The method of claim 5, wherein the first switching signal control circuit comprises a first amplifying circuit, a first differencing circuit, a first PI regulating circuit, a first fundamental wave circuit, a first comparing circuit;
the outputting of the first PWM signal by the first switching signal control circuit according to the input current, the input voltage, and the optimal load value of the wireless power transmission system includes:
receiving the input current through the first amplifying circuit and amplifying the input current by a first preset multiple; the first preset multiple is determined according to the optimal load value of the wireless power transmission system;
acquiring a first difference signal of the amplified input current and the amplified input voltage through the first difference circuit;
receiving and adjusting the first difference signal by the first PI adjustment circuit;
and outputting a first PWM signal for controlling a switching device in a Boost converter through the first comparison circuit according to the output signal of the first PI regulating circuit and the output signal of the first fundamental wave circuit.
7. The method of claim 5, wherein the second switching signal control circuit comprises a second amplifying circuit, a second differencing circuit, a second PI regulating circuit, a second fundamental wave circuit, and a second comparing circuit;
the outputting of the second PWM signal by the second switching signal control circuit according to the load current and the load voltage includes:
receiving the load current through the second amplifying circuit and amplifying the load current by a second preset multiple; the second predetermined multiple is greater than the load value of t times; the load value is determined according to the load voltage and the load current;
acquiring a second difference signal of the amplified input current and the amplified input voltage through the second difference circuit;
receiving and adjusting the second difference signal by the second PI adjustment circuit;
and outputting a second PWM signal for controlling a switching device in the Boost converter through the second comparison circuit according to the output signal of the second PI regulating circuit and the output signal of the second fundamental wave circuit.
8. The method of claim 7, wherein t ≧ 3.
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Application publication date: 20210601 |