CN115800560A - Multi-channel constant-current output unmanned aerial vehicle hovering charging system and method - Google Patents
Multi-channel constant-current output unmanned aerial vehicle hovering charging system and method Download PDFInfo
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- Y02T10/00—Road transport of goods or passengers
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- Y02T10/7072—Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
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Abstract
The invention discloses a multi-constant-current-output unmanned aerial vehicle hovering charging system, which comprises a charging control system; the charging control system comprises a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI (proportional-integral) controller; the sampling module is used for sampling a current signal flowing through the transmitting coil; the Fourier transform module is used for carrying out Fourier transform on the primary side current signal obtained by sampling to obtain current component signals with different frequencies; the mutual inductance estimation module is used for estimating mutual inductance between the transmitting coil and receiving coils of different secondary side systems according to the current component signals with different frequencies; the PI controller is used for outputting corresponding control signals to the control end of the inverter corresponding to different mutual inductance quantities, so that alternating-current voltage output by the inverter is superposed with alternating-current voltage components with different angular frequencies; the angular frequency alternating current voltage components are corresponding to make the current output by the rectifier of each secondary side system constant. According to the invention, modules such as detection and communication are not required to be added on the secondary side, and the lightweight design of the unmanned aerial vehicle side is realized.
Description
Technical Field
The invention relates to a charging system control system and a control method, in particular to a multi-channel constant-current output unmanned aerial vehicle hovering charging system and a multi-channel constant-current output unmanned aerial vehicle hovering charging method.
Background
At present, unmanned aerial vehicles have been widely used in various industries including power inspection, parcel delivery, gas pipeline inspection, military, construction, agriculture, and the like due to their characteristics of flexibility, convenience, economy, and unmanned aerial vehicle. However, due to the limitation of battery capacity, the maximum flight distance of the drone is often only 3 to 33km, which is far from sufficient for some long distance applications. Increasing battery capacity can increase unmanned aerial vehicle's power consumption, can not obviously promote unmanned aerial vehicle's voyage. Therefore, it is necessary to establish a charging device so that the drone can be replenished with energy in the middle of the work. The existing unmanned aerial vehicle wireless charger nest is high in price, can realize functions of automatic return flight, quick charging, edge calculation and the like of an unmanned aerial vehicle, and can excellently complete an energy supply task within 7km of the nest. However, the nests are expensive and not suitable for mass deployment, and a nest can only charge a drone, which is more costly when the number of drones is large.
The multi-unmanned aerial vehicle hovering charging based on the WPT technology provides a good scheme for solving the problems. The advantages of multi-unmanned aerial vehicle hovering charging are three points: firstly, the cost of building a charging base station only used for wireless energy supply is lower than that of a machine nest with the functions of storage, charging and data analysis; secondly, the hovering and charging mode can also directly utilize a flight control system of the unmanned aerial vehicle to resist external interference such as strong wind and avoid using extra auxiliary fixed ground equipment such as a mechanical arm; third, the less characteristics of unmanned aerial vehicle volume and unmanned aerial vehicle avoid the development of collision technique to make many unmanned aerial vehicle hover the charge mode who charges simultaneously at a charge base station and possess the feasibility, can promote each charge base station's utilization ratio greatly after this mode is realized to reduce charge base station's quantity, further reduce cost. However, this novel energy supply mode of charging that hovers of many unmanned aerial vehicles has also brought new difficulty, and unmanned aerial vehicle's flight control system can not guarantee that unmanned aerial vehicle is static in the air completely, and a plurality of unmanned aerial vehicles can not avoid there being irregular shake, and this can cause a plurality of mutual inductances between transmitting coil and a plurality of receiving coil to take place continuous disturbance, leads to the current of the receiving coil of flowing through of multichannel WPT system unstable, influences the charging performance of battery.
In order to ensure the constant current output characteristic under mutual inductance continuous disturbance, a constant current output control method based on mutual inductance estimation is required. However, the existing constant current output control method of the unmanned aerial vehicle hovering and charging system only aims at a single unmanned aerial vehicle hovering and charging system, and a multi-constant current output control method of a multi-unmanned aerial vehicle hovering and charging system does not exist. The existing multi-channel WPT system related research mainly focuses on system design, particularly design of a system primary side structure and a circuit, and related research for overcoming a plurality of mutual inductance continuous disturbances is not available. The main problem of realizing the estimation of many mutual inductances of many unmanned aerial vehicle charging system that hovers based on the relevant research of current multichannel WPT system lies in that traditional secondary side detects the electric current and passes back to the primary side through communication module and exert the mode of controlling and can lead to the heavy burden increase of unmanned aerial vehicle side, leads to the power loss increase of unmanned aerial vehicle flight. Therefore, for a multi-unmanned aerial vehicle hovering charging system, a multi-constant-current output control strategy without adding modules such as extra current detection and communication on a secondary side is needed.
Disclosure of Invention
The invention provides a multi-channel constant-current output unmanned aerial vehicle hovering charging system and method for solving the technical problems in the prior art.
The technical scheme adopted by the invention for solving the technical problems in the prior art is as follows: an unmanned aerial vehicle hovering charging system with multi-channel constant-current output comprises a primary side system for transmitting electromagnetic energy, n secondary side systems for receiving the electromagnetic energy and a charging control system; the primary side system comprises a direct current voltage source, an inverter, a primary side resonance compensation network and a transmitting coil; the direct current voltage source is connected with the direct current input side of the inverter; the primary side resonance compensation network comprises a primary side main capacitor, 1 st to n-1 th primary side compensation capacitors and 1 st to n-1 th primary side compensation inductors; the 1 st to the (n-1) th primary side compensation capacitors are connected in parallel with the 1 st to the (n-1) th primary side compensation inductors in a one-to-one correspondence manner, then connected in series with the primary side main capacitors and the transmitting coils, and then connected in parallel to the alternating current output side of the inverter; each secondary side system comprises a receiving coil, a secondary side resonance compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil are mutually and electromagnetically coupled; the secondary side resonance compensation network comprises a secondary side main capacitor, 1 st to n-1 st secondary side compensation capacitors and 1 st to n-1 st secondary side compensation inductors; the 1 st to the n-1 st secondary side compensation capacitors are connected in parallel with the 1 st to the n-1 st secondary side compensation inductors in a one-to-one correspondence manner, then connected in series with the secondary side main capacitors and the receiving coils, and then connected in parallel to the alternating current input side of the rectifier; the direct current side of the rectifier is respectively connected with the filter capacitor and the charging load in parallel; the charging control system comprises a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI (proportional-integral) controller; the sampling module is used for sampling a current signal flowing through the transmitting coil; the Fourier transform module is used for carrying out Fourier transform on the primary side current signal obtained by sampling to obtain current component signals with different frequencies; the mutual inductance estimation module is used for estimating mutual inductance between the transmitting coil and receiving coils of different secondary side systems according to the current component signals with different frequencies; the PI controller is used for outputting corresponding control signals to the control end of the inverter corresponding to different mutual inductance quantities, so that alternating-current voltage output by the inverter is superposed with alternating-current voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and each angular frequency alternating current voltage component corresponds to make the current output by the rectifier of each secondary system constant.
Further, the sampling module samples the current signal flowing through the transmitting coil at a sampling frequency which is more than or equal to twice the highest working frequency of the primary side system.
Further, the inverter is a full bridge inverter formed by four MOSFETs.
The invention also provides an unmanned aerial vehicle hovering and charging method utilizing the multi-channel constant current output of the unmanned aerial vehicle hovering and charging system, which comprises the following steps:
step 3, estimating mutual inductance between the transmitting coil and the receiving coils of different secondary systems by a mutual inductance estimation module according to current components of different frequencies to obtain an inductance estimation value of mutual inductance between the transmitting coil and the receiving coils of different secondary systems;
step 4, the PI controller performs proportional integral adjustment on inductance estimation values of mutual inductance between the transmitting coil and receiving coils of different secondary systems one by one and then outputs independent control signals to the control end of the inverter, so that alternating voltage output by the inverter is superposition of alternating voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and the amplitude of the alternating voltage component of each angular frequency corresponds to make the current output by the rectifier of each secondary system constant.
Further, step 1 comprises the following substeps:
step 1-1, drawing a primary side system equivalent circuit and each secondary side system equivalent circuit according to a superposition theorem;
step 1-2, calculating the primary harmonicAngular frequency omega of vibration compensation network corresponding system m And the secondary side resonance compensation network of the ith secondary side system corresponds to the system angular frequency omega m The impedance of (a);
1-3, obtaining the total impedance of the output end of the inverter and the total impedance of an ith secondary side system according to a kirchhoff voltage law;
step 1-4, determining the parameters of the primary side resonance compensation network and the secondary side resonance compensation network of each secondary side system, so that the angular frequency of the corresponding system is omega m When the voltage is measured, the impedance of the inductor of the transmitting coil is equal to the absolute value of the impedance of the primary side resonance compensation network, and the signs are opposite; the total impedance of the ith secondary system is 0, and the secondary system works at omega m The total impedance is infinite for the other angular frequency states.
Further, in steps 1 to 4, the method for determining the parameters of the components of the primary side resonance compensation network and the secondary side resonance compensation networks of the secondary side systems includes the following steps:
the parameters of the components of the primary side resonance compensation network are enabled to correspond to the angular frequency of the system to be omega m The following requirements are met:
L p an inductance of the transmitter coil;
make the ith secondary side system at angular frequency omega m Reactance of 0 at angular frequency ω m And when the reactance is infinite in other values, the component parameters of the secondary resonance compensation network of the ith secondary system meet the following conditions:
L si the inductance of the receiving coil of the ith secondary side system;
C sik a kth compensation capacitor in a secondary side resonance compensation network of the ith secondary side system;
L sik and compensating the inductance for the kth compensation inductance in the secondary side resonance compensation network of the ith secondary side system.
Further, in step 3, the method for estimating mutual inductance between the transmitting coil and the receiving coils of different secondary systems is as follows: let M be an estimated value of the mutual inductance between the transmitter coil and the receiver coil of the i-th secondary system esi ，M esi The calculation formula of (c) is as follows:
in the formula of U m Corresponding angular frequency omega for inverter output voltage m Voltage component of, Z pm Angular frequency ω corresponding to the primary system obtained for the measurement m Impedance of (Z) sim For the measured i-th secondary system at the corresponding angular frequency omega m Impedance of alpha i The parameter for compensating the deviation caused by the non-resonance of the circuit of the ith secondary side system.
Further, step 4 comprises the following method steps:
let I Li The current flowing through the load resistor is the current of the ith secondary side system; let I Li_set Setting I for the set value of the current flowing through the load resistor of the ith secondary side system Li_es Is an estimate of the current through the load resistance of the ith secondary system, then I Li_es The calculation formula of (a) is as follows:
will I Li_set And I Li_es Is input into a PI controller, which outputs an input voltage U required for eliminating the deviation m ，U m Inputting the driving signal into a PWM wave generator as an actuator, inputting the required driving signal into a power switch tube of an inverter by the PWM wave generator by adopting an SSPWM method, and outputting a voltage u by the inverter in Satisfies the following conditions:
u in (t)＝U 1 sinω 1 t+…+U n sinω n t；
wherein t is time; adjusting U m So that the current I flowing through the receiving coil Li Is close to the set value I Li_set 。
The invention has the advantages and positive effects that:
the invention discloses an unmanned aerial vehicle hovering charging method with multi-channel constant current output, which adopts a multi-channel WPT system structure based on a multi-Frequency resonance Compensation (MFRC) network, estimates a plurality of mutual inductances in real time by detecting the current of the system flowing through a transmitting coil, and further controls a plurality of secondary side circuits to output constant current according to the estimated mutual inductances.
According to the invention, mutual inductance between the transmitting coil and the receiving coils of different secondary systems is estimated in real time, and the control signal is output to drive the inverter, so that constant current output of different secondary systems is realized, when a plurality of unmanned aerial vehicles are hovered and charged, the multi-channel constant current output unmanned aerial vehicle hovering and charging system keeps multi-constant current output under the condition of multi-mutual inductance continuous disturbance, and the stability and reliability of the charging process are ensured.
The primary side system and the secondary side system of the invention adopt a resonance compensation network formed by a plurality of resonance compensator components, ensure the multi-frequency resonance characteristic of a primary side circuit and the band-pass characteristic of a secondary side circuit, and realize the non-communication multi-constant current output control on the basis.
According to the invention, extra modules such as detection and communication are not required to be added at the secondary side, and the lightweight design of the unmanned aerial vehicle side is realized.
Drawings
Fig. 1 is a circuit schematic diagram of the multi-channel constant-current output unmanned aerial vehicle hovering charging system.
Fig. 2 is an equivalent circuit diagram of the multi-channel constant current output unmanned aerial vehicle hovering charging system.
Fig. 3 is a schematic diagram of the working principle of the multi-channel constant-current output unmanned aerial vehicle hovering charging system.
Fig. 4 is a flowchart of the operation of the multi-channel constant current output unmanned aerial vehicle hovering charging method of the present invention.
In the figure: u shape dc Is the voltage of a DC power supply, u in For the inverter output voltage, i p Is a current flowing through the transmitting coil, C p Primary side main capacitor, C, of primary side resonance compensation network p1 ……C pn-1 Corresponding to the 1 st to the n-1 st primary side compensation capacitors, L p1 ……L pn-1 Corresponding to the 1 st to the n-1 st primary side compensation inductance, L p Inductance of the transmitting coil, R p Parasitic resistance, i, for the primary resonance compensation network and the transmitter coil p For the current flowing through the transmitting coil, L si (i =1,2 … n) is the inductance of the receiving coil of the i-th secondary system, R si (i =1,2 … n) is the parasitic resistance of the receiving coil and the secondary resonance compensation network of the i-th secondary system, M i An inductance of mutual inductance between the transmitter coil and the receiver coil of the i-th secondary system, M iw (w =1,2 … n, and w ≠ i) is an inductance of mutual inductance between the receiver coil of the i-th sub-side system and the receiver coil of the w-th sub-side system, and C si Secondary primary capacitance, C, of a secondary resonance compensation network for the ith secondary system si1 ……C sin-1 1 st to n-1 th secondary side compensation capacitors, L, corresponding to the secondary side resonance compensation network of the ith secondary side system si1 ……L sin-1 1 st to n-1 st secondary side compensation inductances, C, of secondary side resonance compensation networks corresponding to the ith secondary side system di Is the capacitance value, R, of the filter capacitor of the ith secondary side system Li Is the resistance value of the equivalent load of the ith secondary side system i si Is the current flowing through the receiving coil of the i-th secondary system. I is Li Correspond toThe current flowing through the load resistor of the i-th secondary side system.
U in 、I p And I si Corresponds to u in 、i p And i si Of the phasor form, X p For the impedance of the primary resonance compensation network, X si The impedance of the network is compensated for the secondary resonance of the ith secondary system.
R eq1 ……R eqn The equivalent resistors correspond to the full bridge rectifier, the filter capacitor and the equivalent load of the 1 st to nth secondary side systems.
f s The sampling frequency of the sampling module; f. of n For the nth operating frequency of the system, f n The frequency value of (2) is the largest.
I L1_set ……I Ln_set Corresponding to the set load current values of the 1 st to nth secondary side systems.
U 1 ……U n The control voltage corresponding to the output of the PI controller corresponds to an angular frequency of omega 1 To angular frequency of omega n The amplitude of (d) is measured.
I P1 ……I P n Corresponding to the current flowing through the primary winding at an angular frequency of omega 1 To angular frequency of omega n The amplitude of (d) is measured.
S 1 ～S 4 Correspondingly, the first to fourth switching tubes form the inverter; d i1 ～D i4 Corresponding to the first to fourth power diodes constituting the rectifier in the ith secondary side system.
Detailed Description
For a further understanding of the contents, features and effects of the invention, reference will now be made to the following examples, which are to be read in connection with the accompanying drawings, wherein:
the Chinese definitions of the English words and English abbreviations are as follows:
WPT: and (4) wireless power transmission.
A PI controller: and a proportional integral controller.
Referring to fig. 1 to 4, the system includes a primary side system for transmitting electromagnetic energy, n secondary side systems for receiving electromagnetic energy, and a charging control system; the primary side system comprises a direct current voltage source, an inverter, a primary side resonance compensation network and a transmitting coil; the direct current voltage source is connected with the direct current input side of the inverter; the primary side resonance compensation network comprises a primary side main capacitor, 1 st to n-1 th primary side compensation capacitors and 1 st to n-1 th primary side compensation inductors; the 1 st to the n-1 st primary side compensation capacitors are connected in parallel with the 1 st to the n-1 st primary side compensation inductors in a one-to-one correspondence manner, then connected in series with the primary side main capacitors and the transmitting coils and then connected in parallel to the alternating current output side of the inverter; each secondary side system comprises a receiving coil, a secondary side resonance compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil are mutually and electromagnetically coupled; the secondary side resonance compensation network comprises a secondary side main capacitor, 1 st to n-1 st secondary side compensation capacitors and 1 st to n-1 st secondary side compensation inductors; the 1 st to the n-1 st secondary side compensation capacitors are connected in parallel with the 1 st to the n-1 st secondary side compensation inductors in a one-to-one correspondence manner, then connected in series with the secondary side main capacitors and the receiving coils, and then connected in parallel to the alternating current input side of the rectifier; the direct current side of the rectifier is respectively connected with the filter capacitor and the charging load in parallel; the charging control system comprises a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI (proportional-integral) controller; the sampling module is used for sampling a current signal flowing through the transmitting coil; the Fourier transform module is used for carrying out Fourier transform on the primary side current signal obtained by sampling to obtain current component signals with different frequencies; the mutual inductance estimation module is used for estimating mutual inductance between the transmitting coil and receiving coils of different secondary side systems according to the current component signals with different frequencies; the PI controller is used for outputting corresponding control signals to the control end of the inverter corresponding to different mutual inductance quantities, so that alternating-current voltage output by the inverter is superposed with alternating-current voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and each angular frequency alternating current voltage component corresponds to make the current output by the rectifier of each secondary system constant.
The sampling module may include a current sensor by which a current signal flowing through the transmitting coil may be collected. The sampling module can also adopt other current detection devices to collect current signals flowing through the transmitting coil.
The current set value of the receiving coil of each secondary side system can be used as a reference signal of an inverter closed-loop control system, the mutual inductance is converted into a feedback signal of the inverter closed-loop control system through a PI controller, the voltage output by the inverter is decomposed into alternating current voltage components with different angular frequencies through closed-loop control, and after the electromagnetic coupling of the secondary side coil, the generated current is close to the current set value of the receiving coil. The current output from the rectifier of each secondary side system is made constant.
Preferably, the sampling module can sample the current signal flowing through the transmitting coil at a sampling frequency which is greater than or equal to twice the highest operating frequency of the primary side system.
Preferably, the inverter may be a full bridge inverter constructed of four MOSFETs. The inverter can also be a full-bridge inverter formed by four other power switching tubes.
The invention also provides an unmanned aerial vehicle hovering and charging method utilizing the multi-channel constant current output of the unmanned aerial vehicle hovering and charging system, which comprises the following steps:
step 3, estimating mutual inductance between the transmitting coil and the receiving coils of different secondary systems by a mutual inductance estimation module according to current components of different frequencies to obtain an inductance estimation value of mutual inductance between the transmitting coil and the receiving coils of different secondary systems;
step 4, the PI controller performs proportional integral adjustment on inductance estimation values of mutual inductance between the transmitting coil and receiving coils of different secondary systems one by one and then outputs independent control signals to the control end of the inverter, so that alternating voltage output by the inverter is superposition of alternating voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and the amplitude of the alternating voltage component of each angular frequency corresponds to make the current output by the rectifier of each secondary system constant.
Further, step 1 may comprise the following substeps:
step 1-1, a primary side system equivalent circuit and each secondary side system equivalent circuit can be drawn according to the superposition theorem;
step 1-2, calculating the angular frequency omega of the system corresponding to the primary side resonance compensation network m And the secondary side resonance compensation network of the ith secondary side system corresponds to the system angular frequency omega m The impedance of (a);
step 1-3, obtaining the total impedance of the output end of the inverter and the total impedance of the ith secondary side system according to the kirchhoff voltage law;
step 1-4, determining the component parameters of the primary side resonance compensation network and the secondary side resonance compensation network of each secondary side system, so that the angular frequency of the corresponding system is omega m When the voltage is measured, the impedance of the inductor of the transmitting coil is equal to the absolute value of the impedance of the primary side resonance compensation network, and the signs are opposite; the total impedance of the ith secondary system can be made to be 0, and the secondary system works at omega m The total impedance is infinite for the other angular frequency states.
Further, in steps 1 to 4, the method for determining the parameters of the components of the primary side resonance compensation network and the secondary side resonance compensation networks of the secondary side systems may include the following methods:
the parameters of the components of the primary side resonance compensation network can be made to correspond to the angular frequency of the system to be omega m The following requirements are met:
L p an inductance of the transmitter coil;
the ith secondary side system can be enabled to have an angular frequency of omega m Reactance of 0 at angular frequency ω m And when the reactance is infinite in other values, the component parameters of the secondary resonance compensation network of the ith secondary system meet the following conditions:
L si the inductance of the receiving coil of the ith secondary side system;
C sik a kth compensation capacitor in a secondary side resonance compensation network of the ith secondary side system;
L sik and compensating the inductance for the kth compensation inductance in the secondary side resonance compensation network of the ith secondary side system.
Further, in step 3, the method for estimating the mutual inductance between the transmitting coil and the receiving coils of different secondary systems may be as follows: the estimated value of the mutual inductance between the transmitting coil and the receiving coil of the ith secondary side system can be set as M esi ，M esi The calculation formula of (c) can be as follows:
in the formula of U m Corresponding angular frequency omega for inverter output voltage m Voltage component of (Z) pm Angular frequency ω corresponding to the primary system obtained for the measurement m Impedance of (Z) sim For the measured i thThe secondary side system is at the corresponding angular frequency omega m Impedance of alpha i The parameter for compensating the deviation caused by the non-resonance of the circuit of the ith secondary side system.
Further, step 4 may comprise the following method steps:
can be provided with I Li The current flowing through the load resistor is the current of the ith secondary side system; let I Li_set Setting I for the set value of the current flowing through the load resistor of the ith secondary side system Li_es Is an estimate of the current through the load resistance of the ith secondary system, then I Li_es The calculation formula of (c) can be as follows:
can be combined with Li_set And I Li_es Is input into a PI controller which outputs an input voltage U required for eliminating the deviation m ，U m Inputting the driving signal into a PWM wave generator as an actuator, inputting the required driving signal into a power switch tube of an inverter by the PWM wave generator by adopting an SSPWM method, and outputting a voltage u by the inverter in Satisfies the following conditions:
u in (t)＝U 1 sinω 1 t+…+U n sinω n t；
wherein t is time; adjusting U m So that the current I flowing through the receiving coil Li Is close to the set value I Li_set 。
The working process and working principle of the present invention are further explained by a preferred embodiment of the present invention as follows:
an unmanned aerial vehicle hovering charging system with multi-channel constant-current output comprises a primary side system for transmitting electromagnetic energy, n secondary side systems for receiving the electromagnetic energy and a charging control system; the primary side system comprises a direct current voltage source, an inverter, a primary side resonance compensation network and a transmitting coil; the direct current voltage source is connected with the direct current input side of the inverter; the primary side resonance compensation network comprises a primary side main capacitor, 1 st to n-1 th primary side compensation capacitors and 1 st to n-1 th primary side compensation inductors; the 1 st to the n-1 st primary side compensation capacitors are connected in parallel with the 1 st to the n-1 st primary side compensation inductors in a one-to-one correspondence manner, then connected in series with the primary side main capacitors and the transmitting coils and then connected in parallel to the alternating current output side of the inverter; each secondary side system comprises a receiving coil, a secondary side resonance compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil are mutually and electromagnetically coupled; the secondary side resonance compensation network comprises a secondary side main capacitor, 1 st to n-1 st secondary side compensation capacitors and 1 st to n-1 st secondary side compensation inductors; the 1 st to the n-1 st secondary side compensation capacitors are connected in parallel with the 1 st to the n-1 st secondary side compensation inductors in a one-to-one correspondence manner, then connected in series with the secondary side main capacitors and the receiving coils, and then connected in parallel to the alternating current input side of the rectifier; the direct current side of the rectifier is respectively connected with the filter capacitor and the charging load in parallel; the charging control system comprises a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI (proportional-integral) controller; the sampling module is used for sampling a current signal flowing through the transmitting coil; the Fourier transform module is used for carrying out Fourier transform on the primary side current signal obtained by sampling to obtain current component signals with different frequencies; the mutual inductance estimation module is used for estimating mutual inductance between the transmitting coil and receiving coils of different secondary side systems according to the current component signals with different frequencies; the PI controller is used for outputting corresponding control signals to the control end of the inverter corresponding to different mutual inductance quantities, so that alternating-current voltage output by the inverter is superposed with alternating-current voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and each angular frequency alternating current voltage component corresponds to make the current output by the rectifier of each secondary system constant.
The sampling module samples the current signal flowing through the transmitting coil at a sampling frequency which is more than or equal to twice the highest working frequency of the primary side system.
A multi-channel constant current output unmanned aerial vehicle hovering and charging method of the multi-channel constant current output unmanned aerial vehicle hovering and charging system comprises the following steps:
and step A, designing a multi-channel charging system structure and component parameters based on a multi-frequency resonance compensation network by adopting the multi-channel charging system structure based on the multi-frequency resonance compensation network, and ensuring the independence among channels.
B, sampling current signals flowing through the transmitting coil by adopting devices such as a current sensor and the like at a sampling frequency which is more than or equal to twice of the highest operating frequency of the circuit, and obtaining current components with different frequencies by adopting a Fourier Transform (FFT) method through a Fourier Transform module for estimating mutual inductance between the transmitting coil and receiving coils of different secondary systems;
and step C, based on mutual inductance between the transmitting coil and receiving coils of different secondary systems, controlling by adopting a PI controller, and independently controlling the current flowing through the receiving coils by adjusting the input voltage under different frequencies, so that multi-constant-current output is realized, and the stability and reliability of the multi-unmanned aerial vehicle hovering charging system are ensured.
By adopting a superimposed Sinusoidal Pulse Width Modulation (SSPMW), the dc power supply and the full-bridge inverter can generate voltage signals with superimposed voltages of various frequencies. The principle of the method is similar to that of a conventional Sinusoidal Pulse Width Modulation (SPMW), except that the signal wave of the conventional SPWM is a single-frequency sine wave, and the signal wave of the SSPWM is obtained by superimposing sine waves of multiple frequencies. The use of the SSPWM method allows the output voltage to contain components at multiple frequencies, with the amplitude of each frequency component being independently controllable. Therefore, the dc power supply and the full-bridge inverter can be equivalent to an ac voltage source. The equivalent resistance of the full-bridge rectifier, the filter capacitor and the equivalent load is as follows:
R eqi : full-bridge rectifier, filter capacitor and equivalent resistance of equivalent load of ith secondary side system
R Li : resistance of equivalent load of ith secondary side system
Therefore, the MFRC network-based multi-channel WPT system is drawn into an equivalent circuit diagram according to the superposition theorem, which is shown in FIG. 2. U shape in 、I p And I si Is u in 、i p And i si Of the phasor form, X p For the impedance of the primary resonance compensation network, X si The impedance of the secondary side resonance compensation network of the ith secondary side system is expressed as follows:
in the formula, a corner mark i represents the number of a secondary side system; the angle mark k represents the kth group of parallel LC modules of the primary side resonance compensation network or the secondary side resonance compensation network, the 1 st primary side compensation capacitor and the 1 st primary side compensation inductor are connected in parallel to form the 1 st group of primary side parallel LC modules, the kth primary side compensation capacitor and the kth primary side compensation inductor are connected in parallel to form the kth group of primary side parallel LC modules, the angle mark m represents the component of variable at the mth working frequency, and the component is omega m And the system angular frequency corresponding to the mth working frequency.
n is the number of secondary systems; c p Is a primary side main capacitor; c si Is a secondary side main capacitor; c pk A k primary side compensation capacitor; l is pk Compensating the inductance for the kth primary side; c sik A k primary side compensation capacitor of the ith secondary side system; l is sik Compensating inductance for the kth primary side of the ith secondary side system;
for primary resonant compensation network at angular frequency of omega m The reactance of (d);
the secondary side resonance compensation network for the ith secondary side system has an angular frequency of omega m The reactance of (c).
According to kirchhoff's voltage law:
in the formula:
In the formula (I), the compound is shown in the specification,
and
the total impedance of the primary side circuit and the total impedance of the secondary side circuit are respectively expressed as follows
In the formula, R p The parasitic resistance of the transmitting coil of the primary side system and the primary side resonance compensation network; l is p An inductance of the transmitter coil; l is a radical of an alcohol si The inductance of the ith receiving coil;
a secondary side resonance compensation network for the ith secondary side system at an angular frequency of omega m The reactance of (c).
For primary side resonance compensation network at angular frequency of omega m The reactance of (c). R eqi The equivalent resistance is the equivalent resistance of a full bridge rectifier, a filter capacitor and an equivalent load; r is si Parasitic resistances of the receiving coil and the secondary resonance compensation network of the ith secondary system are compensated.
The parameter design in the step 1 comprises parameter design of a primary side resonance compensation network and a secondary side resonance compensation network. In order to ensure the double resonance frequency characteristics of the primary side circuit, the parameter design of the primary side resonance compensation network is satisfied
in order to ensure that the reactance of the secondary side circuit at the corresponding frequency is 0 and the reactance at the non-corresponding frequency is infinite, the parameter design of the secondary side resonance compensation network should meet the following requirements:
in the formula, i is the serial number of the secondary side system; m is the number of angular frequencies.
After parameter design, the current I flowing through the transmitting coil p And a current I flowing through the receiving coil si Satisfy the requirement of
That is, each current flowing through the receiving coil is only related to a variable of one working frequency, and is in a one-to-one correspondence relationship, a component of the current flowing through the transmitting coil under a certain working frequency is also only related to a variable of the secondary side circuit corresponding to the frequency, the primary side circuit can adjust the corresponding current flowing through the receiving coil by adjusting the input voltage under the frequency, and the non-corresponding current flowing through the receiving coil cannot be influenced, so that simultaneous independent transmission of multiple channels is realized.
In step 2, the sampling of the current signal flowing through the transmitting coil at the sampling frequency which is more than or equal to twice the highest operating frequency of the circuit refers to the sampling frequency f of the current sensor s Should be greater than or equal to the highest operating frequency f of the circuit 2 2 times of the sampling time, thereby ensuring that discrete sampling meets the Shannon sampling theorem. The sampled signal is input to a charging control system for further operation, and the charging control system is used for processing and analyzing data and generating a subsequent Pulse Width Modulation (PWM) signal. The effect of the FFT is to discretely sample the current i flowing through the transmit coil p Decomposing the obtained current signal to obtain the current signal at the operating frequency omega m Current component I of pm . On the basis, the estimated mutual inductance M obtained by other known quantities and the primary side detection value esi Is expressed as
In the formula of U m Corresponding angular frequency omega for inverter output voltage m Voltage component of (Z) pm Angular frequency ω corresponding to the primary system obtained for the measurement m Impedance of (Z) sim For the measured i-th secondary system at the corresponding angular frequency omega m Impedance of alpha i The parameter for compensating the deviation caused by the non-resonance of the circuit of the ith secondary side system.
All of the above parameters are known quantities. M esi The estimation of (2) avoids complex phasor calculation and reduces the calculation amount of the charging control system. Multi-channel transmission optimization of WPT system based on MFRC networkPotential, M esi The calculation of the mutual inductance is independent, and the real-time estimation of the multiple mutual inductances is realized.
In step 3, the PI control block diagram based on multiple mutual inductance estimation is shown in fig. 3. In FIG. 3, I Li_set Is a set value of the current flowing through the receiving coil, I Li Is estimated value I Li_es Is expressed as
I Li_set And I Li_es Is input into a PI controller which outputs an input voltage U required for eliminating the deviation m ，U m Inputting the driving signals into a PWM wave generator as an actuator, inputting the required driving signals into four MOSFETs of a full-bridge inverter by adopting an SSPWM method, and then inputting the input voltage u generated by a direct current power supply and the full-bridge inverter in Satisfy the requirement of
u in (t)＝U 1 sinω 1 t+…+U m sinω m t (10)；
Wherein t is time. Following U m Adjustment of the current I flowing through the receiving coil Li Will adjust accordingly to approach the set value I Li_set And multi-constant current output is realized.
The direct current voltage source, the inverter, the primary side resonance compensation network, the transmitting coil, the receiving coil, the secondary side resonance compensation network, the rectifier, the filter capacitor, the charging load, the primary side main capacitor, the primary side compensation inductor, the secondary side main capacitor, the secondary side compensation inductor, the sampling module, the Fourier transform module, the mutual inductance estimation module, the PI controller, the PWM wave generator, the full bridge inverter, the current sensor and the like can all adopt components and functional modules in the prior art, or adopt components and functional modules in the prior art and adopt conventional technical means to construct.
The above-mentioned embodiments are only for illustrating the technical ideas and features of the present invention, and the purpose thereof is to enable those skilled in the art to understand the contents of the present invention and to carry out the same, and the present invention shall not be limited to the embodiments, i.e. the equivalent changes or modifications made within the spirit of the present invention shall fall within the scope of the present invention.
Claims (8)
1. An unmanned aerial vehicle hovering charging system with multi-channel constant-current output is characterized by comprising a primary side system for transmitting electromagnetic energy, n secondary side systems for receiving the electromagnetic energy and a charging control system; the primary side system comprises a direct current voltage source, an inverter, a primary side resonance compensation network and a transmitting coil; the direct current voltage source is connected with the direct current input side of the inverter; the primary side resonance compensation network comprises a primary side main capacitor, 1 st to n-1 th primary side compensation capacitors and 1 st to n-1 th primary side compensation inductors; the 1 st to the n-1 st primary side compensation capacitors are connected in parallel with the 1 st to the n-1 st primary side compensation inductors in a one-to-one correspondence manner, then connected in series with the primary side main capacitors and the transmitting coils and then connected in parallel to the alternating current output side of the inverter; each secondary side system comprises a receiving coil, a secondary side resonance compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil are mutually and electromagnetically coupled; the secondary side resonance compensation network comprises a secondary side main capacitor, 1 st to nth-1 secondary side compensation capacitors and 1 st to nth-1 secondary side compensation inductors; the 1 st to the n-1 st secondary side compensation capacitors are connected in parallel with the 1 st to the n-1 st secondary side compensation inductors in a one-to-one correspondence manner, then connected in series with the secondary side main capacitors and the receiving coils, and then connected in parallel to the alternating current input side of the rectifier; the direct current side of the rectifier is respectively connected with the filter capacitor and the charging load in parallel; the charging control system comprises a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI (proportional-integral) controller; the sampling module is used for sampling a current signal flowing through the transmitting coil; the Fourier transform module is used for carrying out Fourier transform on the primary side current signal obtained by sampling to obtain current component signals with different frequencies; the mutual inductance estimation module is used for estimating mutual inductance between the transmitting coil and receiving coils of different secondary side systems according to the current component signals with different frequencies; the PI controller is used for outputting corresponding control signals to the control end of the inverter corresponding to different mutual inductance quantities, so that alternating-current voltage output by the inverter is superposed with alternating-current voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and each angular frequency alternating current voltage component corresponds to make the current output by the rectifier of each secondary system constant.
2. The multi-channel constant-current-output unmanned aerial vehicle hovering charging system according to claim 1, wherein the sampling module samples the current signal flowing through the transmitting coil at a sampling frequency equal to or greater than twice a highest operating frequency of the primary system.
3. The multi-channel constant-current-output unmanned aerial vehicle hovering charging system according to claim 1, wherein the inverter is a full-bridge inverter formed by four MOSFETs.
4. An unmanned aerial vehicle hovering charging method using multi-channel constant current output of the unmanned aerial vehicle hovering charging system according to any of claims 1 to 3, the method comprising the steps of:
step 1, setting the angular frequency of the mth system as omega m M =1,2 … n, determining the component parameters of the primary and secondary side resonance compensation networks to make the corresponding angular frequency be omega m When the primary side resonance compensation network is used, the impedance of the inductance of the transmitting coil is equal to the impedance absolute value of the primary side resonance compensation network, and the signs are opposite; the total impedance of the ith secondary system is 0, and the secondary system works at omega m The total impedance is infinite in the state of the angular frequency other than the above; i = m;
step 2, a sampling module samples current signals flowing through a transmitting coil, and a Fourier transform module performs Fourier transform on the sampled primary current signals to obtain current components with different frequencies;
step 3, estimating mutual inductance between the transmitting coil and the receiving coils of different secondary systems by a mutual inductance estimation module according to current components of different frequencies to obtain an inductance estimation value of mutual inductance between the transmitting coil and the receiving coils of different secondary systems;
step 4, the PI controller carries out proportional integral adjustment on inductance estimation values of mutual inductance between the transmitting coil and receiving coils of different secondary systems one by one and then outputs independent control signals to the control end of the inverter, so that alternating voltage output by the inverter is superposition of alternating voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system one by one, and the amplitude of the alternating voltage component of each angular frequency corresponds to make the current output by the rectifier of each secondary system constant.
5. The multi-channel constant-current-output unmanned aerial vehicle hovering charging method according to claim 4, wherein step 1 comprises the following substeps:
step 1-1, drawing a primary side system equivalent circuit and each secondary side system equivalent circuit according to a superposition theorem;
step 1-2, calculating the angular frequency omega of the corresponding system of the primary side resonance compensation network m And the secondary side resonance compensation network of the ith secondary side system corresponds to the system angular frequency omega m The impedance of (a);
1-3, obtaining the total impedance of the output end of the inverter and the total impedance of an ith secondary side system according to a kirchhoff voltage law;
step 1-4, determining the parameters of the primary side resonance compensation network and the secondary side resonance compensation network of each secondary side system, so that the angular frequency of the corresponding system is omega m When the primary side resonance compensation network is used, the impedance of the inductance of the transmitting coil is equal to the impedance absolute value of the primary side resonance compensation network, and the signs are opposite; the total impedance of the ith secondary system is 0, and the secondary system works at omega m The total impedance is infinite for other angular frequency states.
6. The multi-channel constant-current-output unmanned aerial vehicle hovering charging method according to claim 5, wherein in steps 1-4, the method for determining the parameters of the primary side resonance compensation network and the components of the secondary side resonance compensation network of each secondary side system comprises the following steps:
the component parameters of the primary side resonance compensation network are enabled to correspond to the angular frequency of the system to be omega m The following requirements are met:
L p an inductance of the transmitter coil;
make the ith secondary side system at angular frequency omega m Reactance of 0 at angular frequency ω m And when the reactance is infinite in other values, the component parameters of the secondary resonance compensation network of the ith secondary system meet the following conditions:
L si the inductance of the receiving coil of the ith secondary side system;
C sik a kth compensation capacitor in a secondary side resonance compensation network of the ith secondary side system;
L sik and compensating the inductance for the kth compensation inductance in the secondary side resonance compensation network of the ith secondary side system.
7. The multi-channel constant-current-output unmanned aerial vehicle hovering charging method according to claim 4, wherein in step 3, the method for estimating the mutual inductance between the transmitting coil and the receiving coils of different secondary systems is as follows: let M be an estimated value of the mutual inductance between the transmitter coil and the receiver coil of the i-th secondary system esi ，M esi The calculation formula of (a) is as follows:
in the formula of U m Corresponding angular frequency omega for inverter output voltage m Voltage component of (Z) pm Angular frequency ω of primary system obtained for measurement m Impedance of (Z) sim For the measured i-th secondary system at the corresponding angular frequency omega m Impedance of (a) i The parameter for compensating the deviation caused by the non-resonance of the circuit of the ith secondary side system.
8. The multi-channel constant-current-output unmanned aerial vehicle hovering charging method according to claim 4, wherein step 4 comprises the following method steps:
let I Li The current flowing through the load resistor is the current of the ith secondary side system; let I Li_set Setting I for the set value of the current flowing through the load resistor of the ith secondary side system Li_es Is an estimate of the current through the load resistance of the ith secondary system, then I Li_es The calculation formula of (a) is as follows:
will I Li_set And I Li_es Is input into a PI controller, which outputs an input voltage U required for eliminating the deviation m ，U m Inputting the driving signal into a PWM wave generator as an actuator, inputting the required driving signal into a power switch tube of an inverter by the PWM wave generator by adopting an SSPWM method, and outputting a voltage u by the inverter in Satisfies the following conditions:
u in (t)＝U 1 sinω 1 t+…+U n sinω n t；
wherein t is time; adjusting U m So that the current I flowing through the receiving coil Li Is close to the set value I Li_set 。
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