CN115800560A - Multi-channel constant current output UAV hovering charging system and method - Google Patents

Abstract

The invention discloses an unmanned aerial vehicle hovering charging system with multiple constant current outputs. The system includes a charging control system; the charging control system includes a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI controller; the sampling module uses It is used to sample the current signal flowing through the transmitting coil; the Fourier transform module is used to perform Fourier transform on the primary current signal obtained by sampling to obtain current component signals of different frequencies; the mutual inductance estimation module is used to obtain current component signals of different frequencies , to estimate the mutual inductance between the transmitting coil and the receiving coil of different secondary systems; the PI controller is used to correspond to different mutual inductance, and output the corresponding control signal to the control terminal of the inverter, so that the AC voltage output by the inverter is different The superposition of angular frequency AC voltage components; each angular frequency AC voltage component corresponds to make the current output by the rectifier of each secondary side system constant. The invention does not need to add detection, communication and other modules on the secondary side, and realizes the lightweight design of the drone side.

Description

Multi-channel constant current output UAV hovering charging system and method

technical field

The invention relates to a charging system control system and control method, in particular to a multi-channel constant current output UAV hovering charging system and method.

Background technique

At present, due to its flexible, convenient, economical and unmanned features, drones have been widely used in various industries, including power inspection, package delivery, natural gas pipeline inspection, military, construction and agriculture, etc. However, limited by battery capacity, the maximum flight distance of drones is often only 3 to 33km, which is far from enough for some long-distance applications. Increasing the battery capacity will increase the power consumption of the drone, and will not significantly increase the range of the drone. Therefore, it is necessary to establish a charging device so that the UAV can replenish energy in the middle of the operation. The existing UAV wireless charging nest is relatively expensive, and can realize functions such as automatic return of the UAV, fast charging, edge computing, etc., and can excellently complete the energy supply task within the 7km operating radius of the nest. However, the price of the machine nest is very expensive, and it is not suitable for mass laying, and one machine nest can only charge one drone, and the cost will be higher when the number of drones is large.

The multi-UAV hovering charging based on WPT technology provides a good solution to the above problems. There are three advantages of multi-UAV hover charging: first, the cost of building a charging base station only for wireless energy supply is lower than that of a nest with storage, charging, and data analysis functions; second, the way of hover charging It is also possible to directly use the UAV's flight control system to resist external interference such as strong winds, avoiding the use of additional auxiliary fixed ground equipment such as manipulators; third, the small size of UAVs and the development of UAV collision avoidance technology make The charging mode of multiple drones hovering and charging at one charging base station at the same time is feasible. After the realization of this mode, the utilization rate of each charging base station can be greatly improved, thereby reducing the number of charging base stations and further reducing costs. However, the novel energy supply method of multi-UAV hovering charging also brings new difficulties. The flight control system of the UAV cannot guarantee that the UAV is completely still in the air. There is irregular jitter, which will cause continuous disturbances in multiple mutual inductances between the transmitting coil and multiple receiving coils, resulting in instability of the current flowing through the receiving coils in the multi-channel WPT system, affecting the charging performance of the battery.

In order to ensure the constant current output characteristics under the continuous disturbance of mutual inductance, it is necessary to adopt a constant current output control method based on mutual inductance estimation. However, the current constant current output control method of the existing UAV hovering charging system is only for the single UAV hovering charging system, and there is no multi-constant current output control method for the multi-UAV hovering charging system. The existing multi-channel WPT system related research mainly focuses on system design, especially the design of the primary side structure and circuit of the system, and there is no related research on overcoming continuous disturbances of multiple mutual inductances. Based on the existing multi-channel WPT system related research, the main problem of realizing the multi-mutual inductance estimation of the multi-UAV hovering charging system is that the traditional way of detecting the current on the secondary side and sending it back to the primary side through the communication module to apply control will lead to The load on the side of the UAV increases, resulting in an increase in the power loss of the UAV flight. Therefore, for the multi-UAV hovering charging system, a multi-constant current output control strategy that does not require additional current detection and communication modules on the secondary side is needed.

Contents of the invention

The present invention provides a multi-channel constant current output UAV hovering charging system and method to solve the technical problems in the known technology.

The technical solution adopted by the present invention to solve the technical problems existing in the known technology is: a multi-channel constant current output UAV hovering charging system, the system includes a primary side system for emitting electromagnetic energy, n The secondary side system and charging control system for receiving electromagnetic energy; the primary side system includes a DC voltage source, an inverter, a primary side resonance compensation network and a transmitting coil; the DC voltage source is connected to the DC input side of the inverter; the primary side resonance The compensation network includes the primary capacitor, the 1st to n-1 primary compensation capacitors, and the 1st to n-1 primary compensation inductors; the 1st to n-1 primary compensation capacitors correspond one-to-one with The 1st to n-1th primary side compensation inductors are connected in parallel and then connected in series, and then connected in series with the primary side main capacitor and transmitting coil and connected to the AC output side of the inverter; each secondary side system includes a receiving coil, secondary side resonance Compensation network, rectifier, filter capacitor and charging load; mutual electromagnetic coupling between the transmitting coil and each receiving coil; the secondary resonance compensation network includes the secondary main capacitor, the 1st to n-1th secondary compensation capacitors, the 1st to the n-1th secondary side compensation inductance; the 1st to n-1th secondary side compensation capacitors are connected in parallel with the 1st to n-1th secondary side compensation inductance and then connected in series, and then connected to the secondary side main capacitor and The receiving coil is connected in series and connected to the AC input side of the rectifier; the DC side of the rectifier is respectively connected in parallel with the filter capacitor and the charging load; the charging control system includes a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI controller; the sampling module is used It is used to sample the current signal flowing through the transmitting coil; the Fourier transform module is used to perform Fourier transform on the primary current signal obtained by sampling to obtain current component signals of different frequencies; the mutual inductance estimation module is used to obtain current component signals of different frequencies signal, to estimate the mutual inductance between the transmitting coil and the receiving coil of different secondary systems; the PI controller is used to correspond to different mutual inductance, and output the corresponding control signal to the control terminal of the inverter, so that the AC voltage output by the inverter is The superposition of AC voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system, and the corresponding angular frequency AC voltage components make the output current of the rectifier of each secondary system constant.

Further, the sampling module samples the current signal flowing through the transmitting coil at a sampling frequency greater than or equal to twice the maximum operating frequency of the primary system.

Further, the inverter is a full-bridge inverter composed of four MOSFETs.

The present invention also provides a multi-channel constant-current output UAV hovering charging method using the above-mentioned multi-channel constant-current output UAV hovering charging system, the method comprising the following steps:

Step 1, set the angular frequency of the mth system as ω _m , m=1, 2...n, determine the component parameters of the primary and secondary resonance compensation networks, so that when the corresponding angular frequency is ω _m , the impedance of the inductance of the transmitting coil The absolute value of the impedance of the primary side resonant compensation network is equal, and the sign is opposite; the total impedance of the i-th secondary system is 0, and the total impedance is infinite when the secondary system works at an angular frequency other than ω _m ; i= m;

Step 2, the sampling module samples the current signal flowing through the transmitting coil, and the Fourier transform module performs Fourier transform on the sampled primary current signal to obtain current components of different frequencies;

Step 3, the mutual inductance estimation module estimates the mutual inductance between the transmitting coil and the receiving coils of different secondary systems according to the current components of different frequencies, and obtains the estimated value of the mutual inductance between the transmitting coil and the receiving coils of different secondary systems ;

Step 4, the PI controller performs proportional integral adjustment on the estimated value of the mutual inductance between the transmitting coil and the receiving coil of different secondary systems, and then outputs an independent control signal to the inverter control terminal, so that the output of the inverter The AC voltage is the superposition of AC voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system, and the amplitude of the AC voltage component of each angular frequency corresponds to make the output current of the rectifier of each secondary system constant.

Further, step 1 includes the following sub-steps:

Step 1-1, draw the equivalent circuit of the primary side system and the equivalent circuit of each secondary side system according to the superposition theorem;

Step 1-2, calculating the impedance of the primary side resonance compensation network corresponding to the system angular frequency ω _m , and the impedance of the secondary side resonance compensation network of the i-th secondary system corresponding to the system angular frequency ω _m ;

Steps 1-3, according to Kirchhoff's voltage law, obtain the total impedance of the output terminal of the inverter and the total impedance of the i-th secondary side system;

Step 1-4, determine the primary side resonance compensation network and the component parameters of the secondary side resonance compensation network of each secondary side system, so that when the corresponding system angular frequency is _ωm , the impedance of the inductance of the transmitting coil is the same as that of the primary side resonance compensation network The absolute values of the impedances are equal and the signs are opposite; the total impedance of the i-th secondary system is 0, and the total impedance of the secondary system is infinite when it works at an angular frequency other than ω _m .

Further, in step 1-4, the method for determining the component parameters of the primary resonance compensation network and the secondary resonance compensation network of each secondary system includes the following methods:

Make the component parameters of the primary side resonance compensation network satisfy when the corresponding system angular frequency is _ωm :

为原边谐振补偿网络在角频率为ω_m处的电抗；

is the reactance of the primary side resonant compensation network at the angular frequency ω _m ;

L _p is the inductance of the transmitting coil;

Let the reactance of the i-th secondary system be 0 when the angular frequency is ω _m , and the reactance be infinite when the angular frequency is other than ω _m , then make the element of the secondary resonance compensation network of the i-th secondary system The device parameters meet:

为第i个副边系统的副边谐振补偿网络在角频率为ω_m处的电抗；

is the reactance of the secondary resonant compensation network of the ith secondary system at the angular frequency ω _m ;

L _si is the inductance of the receiving coil of the i-th secondary system;

C _sik is the kth compensation capacitor in the secondary resonance compensation network of the i-th secondary system;

L _sik is the kth compensation inductance in the secondary resonance compensation network of the ith secondary system.

Further, 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 the estimated value of the mutual inductance between the transmitting coil and the receiving coil of the i-th secondary system be M The calculation formula of _esi and M _esi is as follows:

In the formula, U _m is the voltage component of the inverter output voltage corresponding to the angular frequency ω _m , Z _pm is the measured impedance of the primary side system corresponding to the angular frequency ω _m , and Z _sim is the measured i-th secondary system at The impedance corresponding to the angular frequency ω _m , α _i is a parameter used to compensate the deviation caused by the circuit non-resonance of the ith secondary side system.

Further, step 4 includes the following method steps:

Let I _Li be the current flowing through the load resistance of the i-th secondary system; let I _{Li_set} be the set value of the current flowing through the load resistance of the i-th secondary system, let I _{Li_es} be the i-th secondary system The estimated value of the current flowing through the load resistance, then the calculation formula of I _{Li_es} is as follows:

Input the deviation of I _{Li_set} and I _{Li_es} into the PI controller, and the output of the PI controller is the input voltage U _m required to eliminate the deviation, and U _m is input into the PWM wave generator as an actuator, and the PWM wave generator adopts SSPWM The method is to input the required driving signal into the power switch tube of the inverter, and the output voltage u _in of the inverter satisfies:

u _in (t)＝U ₁ sinω ₁ t+…+U _n sinω _n t;

In the formula, t is time; U _m is adjusted so that the current I _Li flowing through the receiving coil is close to the set value I _{Li_set} .

The advantages and positive effects that the present invention has are:

A multi-channel constant current output UAV hovering charging method of the present invention adopts a multi-channel WPT system structure based on a multiple frequency resonance compensation (Multiple Frequency Resonating Compensation, MFRC) network, and transmits The current of the coil estimates multiple mutual inductances in real time, and then controls the constant current output of multiple secondary side circuits according to the estimated multiple mutual inductances.

The invention estimates the mutual inductance between the transmitting coil and the receiving coils of different secondary systems in real time, outputs control signals to drive the inverter, and realizes the constant current output of different secondary systems, so that when multiple drones are hovering and charging, multiple The UAV hovering charging system with channel constant current output maintains multiple constant current outputs under the condition of continuous disturbance of multiple mutual inductances, ensuring the stability and reliability of the charging process.

The primary and secondary side systems of the present invention adopt a resonant compensation network composed of multiple resonant compensator components, which ensures the multi-frequency resonance characteristics of the primary side circuit and the bandpass characteristics of the secondary side circuit, and on this basis realizes no Communication multiple constant current output control.

The invention does not need to add additional modules such as detection and communication on the secondary side, and realizes the lightweight design of the drone side.

Description of drawings

Fig. 1 is a schematic circuit diagram of a drone hovering charging system with multi-channel constant current output according to the present invention.

Fig. 2 is an equivalent circuit diagram of a drone hovering charging system with multi-channel constant current output according to the present invention.

Fig. 3 is a schematic diagram of the working principle of a drone hovering charging system with multi-channel constant current output according to the present invention.

Fig. 4 is a working flow chart of a multi-channel constant current output drone hovering charging method of the present invention.

In the figure: U _dc is the voltage of the DC power supply, u _in is the output voltage of the inverter, _ip is the current flowing through the transmitting coil, C _p is the main capacitance of the primary side resonant compensation network of the primary side, C _p1 ... C _{pn -1} corresponds to the 1st to n-1th primary side compensation capacitance, L _p1 ... L _pn-1 corresponds to the 1st to n-1th primary side compensation inductance, L _p is the inductance of the transmitting coil, R _p is the parasitic resistance of the primary resonant compensation network and the transmitting coil, _ip is 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 of the i-th secondary system and the secondary resonant compensation network, M _i is the mutual inductance between the transmitting coil and the receiving coil of the i-th secondary system, M _iw (w=1,2...n, and w≠i) is the mutual inductance between the receiving coil of the i-th secondary system and the receiving coil of the w-th secondary system, C _si is the i-th secondary The secondary side main capacitance of the secondary side resonant compensation network of the side system, C _si1 ... C _sin-1 corresponds to the 1st to n-1th secondary side compensation capacitors of the secondary side resonant compensation network of the i-th secondary system, L _si1 ... L _sin-1 corresponds to the 1st to n-1th secondary side compensation inductance of the secondary side resonant compensation network of the i-th secondary side system, and C _di is the capacitance of the filter capacitor of the i-th secondary side system value, R _Li is the resistance value of the equivalent load of the i-th secondary system, and i _si is the current flowing through the receiving coil of the i-th secondary system. I _Li corresponds to the current flowing through the load resistor of the ith secondary side system.

U _in , I _p and I _si correspond to the phasor forms of u _in , i _p and i _si , X _p is the impedance of the primary resonance compensation network, and X _si is the impedance of the secondary resonance compensation network of the i-th secondary system impedance.

对应为原边谐振补偿网络在角频率为ω₁至角频率为ω_n处的电抗电抗

对应为原边系统在角频率为ω₁至角频率为ω_n处的电流。

Corresponding to the reactance reactance of the primary side resonant compensation network at the angular frequency ω ₁ to the angular frequency ω _n

Corresponding to the current of the primary side system at angular frequency ω ₁ to angular frequency ω _n .

对应为第1个至第n个副边系统的副边谐振补偿网路在角频率为ω₁处的电抗。

Corresponding to the reactance at the angular frequency ω ₁ of the secondary resonance compensation network of the 1st to nth secondary systems.

对应为第1个至第n个副边系统的在角频率为ω_n处的电流。

Corresponding to the current at the angular frequency ω _n of the 1st to nth secondary systems.

对应为第1个至第n个副边系统的在角频率为ω_n处的电流。

Corresponding to the current at the angular frequency ω _n of the 1st to nth secondary systems.

对应为原边系统在角频率为ω₁至角频率为ω_n处的输入电压。

Corresponding to the input voltage of the primary side system at angular frequency ω ₁ to angular frequency ω _n .

对应为第1至第n第1个至第n个副边系统的副边谐振补偿网路在角频率为ω₁处的电抗。

Corresponding to the reactance at the angular frequency ω ₁ of the secondary side resonant compensation network of the 1st to nth secondary side systems.

对应为第1个至第n个副边系统的在角频率为ω_n处的电流。

Corresponding to the current at the angular frequency ω _n of the 1st to nth secondary systems.

R _eq1 ... R _eqn correspond to the equivalent resistances of the full-bridge rectifiers, filter capacitors and equivalent loads of the first to nth secondary systems.

f _s is the sampling frequency of the sampling module; f _n is the nth operating frequency of the system, and the frequency value of f _n is the largest.

I _{L1_set} ... I _{Ln_set} corresponds to the set value of the load current of the 1st to the nth secondary side system.

_{U 1 . _}

I _P1 ... I _{P n} corresponds to the magnitude of the current flowing through the primary coil at the angular frequency ω ₁ to the angular frequency ω _n .

S ₁ -S ₄ correspond to the first to fourth switching tubes constituting the inverter; D _i1 -D _i4 correspond to the first to fourth power diodes constituting the rectifier in the i-th secondary system.

Detailed ways

In order to further understand the invention content, characteristics and effects of the present invention, the following embodiments are enumerated hereby, and detailed descriptions are as follows in conjunction with the accompanying drawings:

The Chinese definitions of English words and English abbreviations are as follows:

WPT: Wireless Power Transfer.

PI Controller: Proportional Integral Controller.

Please refer to Figures 1 to 4, the system includes a primary system for transmitting electromagnetic energy, n secondary systems for receiving electromagnetic energy, and a charging control system; the primary system includes a DC voltage source, an inverter, and a primary The side resonance compensation network and the transmitting coil; the DC voltage source is connected to the DC input side of the inverter; the primary side resonance compensation network includes the primary side main capacitor, the 1st to n-1th primary side compensation capacitors, the 1st to nth -1 primary side compensation inductor; the 1st to n-1th primary side compensation capacitors are connected in parallel with the 1st to n-1th primary side compensation inductors and then connected in series, and then connected in series with the primary side main capacitor and the transmitting coil Then connected in parallel to the AC output side of the inverter; each secondary system includes a receiving coil, a secondary resonant compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil are electromagnetically coupled; the secondary The resonant compensation network includes the secondary main capacitor, the 1st to n-1th secondary compensation capacitors, the 1st to n-1th secondary compensation inductors; the 1st to n-1th secondary compensation capacitors correspond one-to-one It is connected in parallel with the 1st to n-1th secondary side compensation inductors and then connected in series, and then connected in series with the secondary side main capacitor and receiving coil and connected to the AC input side of the rectifier; the DC side of the rectifier is respectively connected in parallel with the filter capacitor and the charging load; The charging control system includes a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI controller; the sampling module is used to sample the current signal flowing through the transmitting coil; the Fourier transform module is used to process the primary current signal obtained by sampling Fourier transform to obtain current component signals of different frequencies; the mutual inductance estimation module is used to estimate the mutual inductance between the transmitting coil and the receiving coil of different secondary side systems according to the current component signals of different frequencies; the PI controller is used to correspond to different mutual inductance output the corresponding control signal to the control terminal of the inverter, so that the AC voltage output by the inverter is the superposition of AC voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary side system one by one, and each angular frequency The frequency of the AC voltage component corresponds to making the current output by the rectifiers of each secondary system constant.

The sampling module may include a current sensor, and the current signal flowing through the transmitting coil may be collected by the current sensor. The sampling module can also use other current detection devices to collect current signals flowing through the transmitting coil.

The set value of the receiving coil current of each secondary side system can be used as the reference signal of the inverter closed-loop control system, and the mutual inductance can be converted into the feedback signal of the inverter closed-loop control system through the PI controller. Through the closed-loop control, the The voltage output by the inverter is decomposed into AC voltage components with different angular frequencies, and after being electromagnetically coupled by the secondary coil, the generated current is close to the set value of the current of the receiving coil. Make the current output by the rectifiers of each secondary side system constant.

Preferably, the sampling module can sample the current signal flowing through the transmitting coil at a sampling frequency greater than or equal to twice the maximum operating frequency of the primary system.

Preferably, the inverter may be a full-bridge inverter composed of four MOSFETs. The inverter can also be a full-bridge inverter composed of four other power switch tubes.

The present invention also provides a multi-channel constant-current output UAV hovering charging method using the above-mentioned multi-channel constant-current output UAV hovering charging system, the method comprising the following steps:

Step 1, set the angular frequency of the mth system as ω _m , m=1, 2...n, determine the component parameters of the primary and secondary resonance compensation networks, so that when the corresponding angular frequency is ω _m , the impedance of the inductance of the transmitting coil The absolute value of the impedance of the primary side resonant compensation network is equal, and the sign is opposite; the total impedance of the i-th secondary system is 0, and the total impedance is infinite when the secondary system works at an angular frequency other than ω _m ; i= m;

Step 2, the sampling module samples the current signal flowing through the transmitting coil, and the Fourier transform module performs Fourier transform on the sampled primary current signal to obtain current components of different frequencies;

Step 3, the mutual inductance estimation module estimates the mutual inductance between the transmitting coil and the receiving coils of different secondary systems according to the current components of different frequencies, and obtains the estimated value of the mutual inductance between the transmitting coil and the receiving coils of different secondary systems ;

Step 4, the PI controller performs proportional integral adjustment on the estimated value of the mutual inductance between the transmitting coil and the receiving coil of different secondary systems, and then outputs an independent control signal to the inverter control terminal, so that the output of the inverter The AC voltage is the superposition of AC voltage components with different angular frequencies; each angular frequency corresponds to the system angular frequency of the secondary system, and the amplitude of the AC voltage component of each angular frequency corresponds to make the output current of the rectifier of each secondary system constant.

Further, step 1 may include the following sub-steps:

Step 1-1, draw the equivalent circuit of the primary side system and the equivalent circuit of each secondary side system according to the superposition theorem;

Step 1-2, can calculate the impedance of the primary side resonance compensation network corresponding to the system angular frequency ω _m , and the impedance of the secondary resonance compensation network of the i-th secondary system corresponding to the system angular frequency ω _m ;

In steps 1-3, according to Kirchhoff's voltage law, the total impedance of the output terminal of the inverter and the total impedance of the i-th secondary side system can be obtained;

Steps 1-4, determine the primary side resonance compensation network and the component parameters of the secondary side resonance compensation network of each secondary side system, so that when the corresponding system angular frequency is _ωm , the impedance of the inductance of the transmitting coil is the same as that of the primary side resonance compensation network The absolute values of the impedances are equal and the signs are opposite; the total impedance of the i-th secondary system can be made to be 0, and the total impedance of the secondary system is infinite when it works at an angular frequency other than ω _m .

Further, in step 1-4, the method for determining the component parameters of the primary resonance compensation network and the secondary resonance compensation network of each secondary system may include the following methods:

The parameters of the components of the primary resonance compensation network can be satisfied when the corresponding system angular frequency is ω _m :

为原边谐振补偿网络在角频率为ω_m处的电抗；

is the reactance of the primary side resonant compensation network at the angular frequency ω _m ;

L _p is the inductance of the transmitting coil;

The reactance of the i-th secondary system can be 0 when the angular frequency is ω _m , and the reactance is infinite when the angular frequency is other than ω _m , then the secondary resonance compensation network of the i-th secondary system can be Component parameters meet:

为第i个副边系统的副边谐振补偿网络在角频率为ω_m处的电抗；

is the reactance of the secondary resonant compensation network of the ith secondary system at the angular frequency ω _m ;

L _si is the inductance of the receiving coil of the i-th secondary system;

C _sik is the kth compensation capacitor in the secondary resonance compensation network of the i-th secondary system;

L _sik is the kth compensation inductance in the secondary resonance compensation network of the ith secondary system.

Further, in step 3, the method for estimating the mutual inductance between the transmitting coil and the receiving coils of different secondary systems can be as follows: the estimated value of the mutual inductance between the transmitting coil and the receiving coil of the i-th secondary system can be set is M _esi , the calculation formula of M _esi can be as follows:

In the formula, U _m is the voltage component of the inverter output voltage corresponding to the angular frequency ω _m , Z _pm is the measured impedance of the primary side system corresponding to the angular frequency ω _m , and Z _sim is the measured i-th secondary system at The impedance corresponding to the angular frequency ω _m , α _i is a parameter used to compensate the deviation caused by the circuit non-resonance of the ith secondary side system.

Further, step 4 may include the following method steps:

Let I _Li be the current flowing through the load resistance of the i-th secondary system; let I _{Li_set} be the set value of the current flowing through the load resistance of the i-th secondary system, and let I _{Li_es} be the i-th secondary The estimated value of the current flowing through the load resistance of the system, the calculation formula of I _{Li_es} can be as follows:

The deviation of I _{Li_set} and I _{Li_es} can be input into the PI controller, and the output of the PI controller is the input voltage U _m required to eliminate the deviation, and U _m is input into the PWM wave generator as an actuator, and the PWM wave generator adopts The SSPWM method inputs the required driving signal into the power switch tube of the inverter, and the output voltage u _in of the inverter satisfies:

u _in (t)＝U ₁ sinω ₁ t+…+U _n sinω _n t;

In the formula, t is time; U _m is adjusted so that the current I _Li flowing through the receiving coil is close to the set value I _{Li_set} .

The workflow and working principle of the present invention are further described below with a preferred embodiment of the present invention:

A multi-channel constant current output UAV hovering charging system, the system includes a primary system for transmitting electromagnetic energy, n secondary systems for receiving electromagnetic energy and a charging control system; the primary system includes a DC Voltage source, inverter, primary side resonant compensation network and transmitting coil; the DC voltage source is connected to the DC input side of the inverter; the primary side resonant compensation network includes the primary side main capacitor, the 1st to n-1th primary sides Compensation capacitance, the 1st to n-1th primary side compensation inductors; the 1st to n-1th primary side compensation capacitors are connected in parallel with the 1st to n-1th primary side compensation inductors in one-to-one correspondence, and then connected in series with The main capacitor of the primary side and the transmitting coil are connected in series and connected to the AC output side of the inverter; each secondary system includes a receiving coil, a secondary resonant compensation network, a rectifier, a filter capacitor and a charging load; the transmitting coil and each receiving coil Electromagnetic coupling between each other; the secondary resonance compensation network includes the secondary main capacitor, the 1st to n-1th secondary compensation capacitors, the 1st to n-1th secondary compensation inductors; the 1st to n-1th The secondary side compensation capacitors are connected in parallel with the 1st to n-1th secondary side compensation inductors one by one and then connected in series, and then connected in series with the secondary side main capacitor and the receiving coil and connected to the AC input side of the rectifier; the DC side of the rectifier respectively It is connected in parallel with the filter capacitor and the charging load; the charging control system includes a sampling module, a Fourier transform module, a mutual inductance estimation module and a PI controller; the sampling module is used for sampling the current signal flowing through the transmitting coil; the Fourier transform module is used for The primary current signal obtained by sampling is Fourier transformed to obtain current component signals of different frequencies; the mutual inductance estimation module is used to estimate the mutual inductance between the transmitting coil and the receiving coil of different secondary systems according to the current component signals of different frequencies; The PI controller is used to correspond to different mutual inductances, output corresponding control signals to the control terminal of the inverter, so that the AC voltage output by the inverter is the superposition of AC voltage components with different angular frequencies; the system of each angular frequency and the secondary system The angular frequencies are in one-to-one correspondence, and the alternating voltage components of each angular frequency correspond to make the current output by the rectifiers of each secondary system constant.

The sampling module samples the current signal flowing through the transmitting coil at a sampling frequency greater than or equal to twice the maximum operating frequency of the primary system.

A multi-channel constant current output UAV hovering charging method utilizing the above-mentioned multi-channel constant current output UAV hovering charging system, the method includes the following steps:

In step A, adopt the multi-channel charging system structure based on the multi-frequency resonance compensation network, design the multi-channel charging system structure and components parameters based on the multi-frequency resonance compensation network, and ensure the independence of each channel.

Step B, using a device such as a current sensor, sampling the current signal flowing through the transmitting coil at a sampling frequency greater than or equal to twice the highest operating frequency of the circuit, using a Fourier transform module, through Fast Fourier Transform (FFT) The method obtains the current components of different frequencies, which are used to estimate the mutual inductance between the transmitting coil and the receiving coil of different secondary systems;

Step C, based on the mutual inductance between the transmitting coil and the receiving coils of different secondary systems, the PI controller is used to control the current flowing through the receiving coils independently by adjusting the input voltage at different frequencies, so as to realize multiple constant current outputs and ensure multiple Stability and reliability of drone hover charging system.

Using superposed sinusoidal pulse width modulation (Superposed Sinusoidal Pulse WidthModulation, SSPMW) can make the DC power supply and the full-bridge inverter generate voltage signals with multiple frequency voltages superimposed. The principle of this method is similar to the conventional sinusoidal pulse width modulation (Sinusoidal Pulse Width Modulation, SPMW), the difference is that the signal wave of the conventional SPWM method is a single-frequency sine wave, while the signal wave of SSPWM is superimposed by multiple frequency sine waves get. In the case of using the SSPWM method, it can be realized that the output voltage contains multiple frequency components, and the amplitude of each frequency component is independently controllable. Therefore, the DC power supply and the full-bridge inverter can be equivalent to AC voltage sources. The equivalent resistance of the full bridge rectifier, filter capacitor and equivalent load is:

R _eqi : the equivalent resistance of the full-bridge rectifier, filter capacitor and equivalent load of the i-th secondary system

R _Li : the resistance of the equivalent load of the i-th secondary side system

Therefore, the equivalent circuit diagram of the multi-channel WPT system based on the MFRC network is drawn according to the superposition theorem, as shown in FIG. 2 . U _in , I _p and I _si are the phasor forms of u _in , i _p and i _si , X _p is the impedance of the primary resonance compensation network, and X _si is the impedance of the secondary resonance compensation network of the ith secondary system , whose expression is as follows:

In the formula, the subscript i represents the serial number of the secondary side system; the subscript k represents the primary side resonance compensation network or the kth group of parallel LC modules of the secondary side resonance compensation network, the first primary side compensation capacitor and the first primary side compensation After the inductance is connected in parallel, it becomes the first group of primary side parallel connection LC modules. After the kth primary side compensation capacitor is connected in parallel with the kth primary side compensation inductor, it becomes the kth group of primary side parallel connection LC modules. The subscript m indicates that the variable is working in the mth The component at the frequency, ω _m is the system angular frequency corresponding to the mth operating frequency.

为原边谐振补偿网络在角频率为ω_m处的电抗；

为第i个副边系统的副边谐振补偿网络在角频率为ω_m处的电抗。n is the number of secondary side systems; C _p is the main capacitance of the primary side; C _si is the main capacitance of the secondary side _; C _pk is the kth primary side compensation capacitor; L _pk is the kth primary side compensation inductance; The kth primary compensation capacitance of the i secondary system; L _sik is the k primary compensation inductance of the i secondary system;

is the reactance of the primary side resonant compensation network at the angular frequency ω _m ;

is the reactance of the secondary resonant compensation network of the ith secondary system at the angular frequency ω _m .

According to Kirchhoff's voltage law:

In the formula:

为在角频率为ω_m处的输入电压；

为在角频率为ω_m处的原边电流；

为在角频率为ω_m处的原边总阻抗；

为在角频率为ω_m处第i个副边系统的电流；M_i为第i个副边系统的接收线圈和原边系统的发射线圈之间的互感；

为在角频率为ω_m处第i个副边系统的总阻抗；M_iw为第i个副边系统的接收线圈和第w个副边系统的接收线圈之间的互感。

is the input voltage at the angular frequency ω _m ;

is the primary current at the angular frequency ω _m ;

is the total impedance of the primary side at the angular frequency ω _m ;

is the current of the i-th secondary system at the angular frequency ω _m ; M _i is the mutual inductance between the receiving coil of the i-th secondary system and the transmitting coil of the primary system;

is the total impedance of the i-th secondary system at the angular frequency ω _m ; M _iw is the mutual inductance between the receiving coil of the i-th secondary system and the receiving coil of the w-th secondary system.

和

分别为原边电路的总阻抗和副边电路的总阻抗，其表达式如下In the formula,

and

are the total impedance of the primary circuit and the total impedance of the secondary circuit respectively, and their expressions are as follows

为第i个副边系统的副边谐振补偿网络在角频率为ω_m处的电抗。

为原边谐振补偿网络在角频率为ω_m处的电抗。R_eqi为全桥整流器、滤波电容和等效负载的等效电阻；R_si为第i个副边系统的接收线圈和副边谐振补偿网络的寄生电阻。In the formula, R _p is the parasitic resistance of the transmitting coil of the primary system and the primary resonance compensation network; L _p is the inductance of the transmitting coil; L _si is the inductance of the i-th receiving coil;

is the reactance of the secondary resonant compensation network of the ith secondary system at the angular frequency ω _m .

is the reactance of the primary side resonant compensation network at the angular frequency ω _m . R _eqi is the equivalent resistance of the full-bridge rectifier, filter capacitor and equivalent load; R _si is the parasitic resistance of the receiving coil of the i-th secondary system and the secondary resonance compensation network.

The parameter design in step 1 includes the parameter design of the primary side resonance compensation network and the secondary side resonance compensation network. In order to ensure the double resonant frequency characteristics of the primary side circuit, the parameter design of the primary side resonant compensation network should meet

为为原边谐振补偿网络在角频率为ω_m处的电抗；

is the reactance of the primary side resonance compensation network at the angular frequency ω _m ;

In order to ensure that the reactance of the secondary side circuit is 0 at the corresponding frequency and the reactance at the non-corresponding frequency is infinite, the parameter design of the secondary side resonance compensation network should meet:

In the formula, i is the serial number of the secondary side system; m is the serial number of the angular frequency.

After parameter design, the current I _p flowing through the transmitting coil and the current I _si flowing through the receiving coil satisfy

That is, each current flowing through the receiving coil is only related to the variable of one operating frequency, which is a one-to-one correspondence, and the component of the current flowing through the transmitting coil at a certain operating frequency is only related to the frequency corresponding to the secondary circuit. The variables are related, the primary side circuit adjusts the input voltage at this frequency to adjust the corresponding current flowing through the receiving coil, and will not affect the non-corresponding current flowing through the receiving coil, realizing multi-channel simultaneous independent transmission.

In step 2, said sampling the current signal flowing through the transmitting coil with a sampling frequency greater than or equal to twice the highest operating frequency of the circuit means that the sampling frequency _f of the current sensor should be greater than or equal to _twice the highest operating frequency f of the circuit, so that Discrete sampling is guaranteed to satisfy Shannon's sampling theorem. The sampled signal is input to the charging control system for further calculation, and the charging control system is used for data processing and analysis and subsequent pulse width modulation (Pulse width Modulation, PWM) signal generation. The function of the FFT is to decompose the current signal obtained by discretely sampling the current _ip flowing through the transmitting coil to obtain its current component I _pm at the operating frequency ω _m . On this basis, the expression of the estimated mutual inductance M _esi obtained by using other known quantities and the detection value of the primary side is

In the formula, U _m is the voltage component of the inverter output voltage corresponding to the angular frequency ω _m , Z _pm is the measured impedance of the primary side system corresponding to the angular frequency ω _m , and Z _sim is the measured i-th secondary system at The impedance corresponding to the angular frequency ω _m , α _i is a parameter used to compensate the deviation caused by the circuit non-resonance of the ith secondary side system.

All the above parameters are known quantities. _Mesi estimation avoids complex phasor calculations and reduces the computational load of the charging control system. Due to the multi-channel transmission advantage of the WPT system based on the MFRC network, the calculation of _Mesi is independent of each other, realizing the real-time estimation of multiple mutual inductances.

In step 3, the PI control block diagram based on multi-mutual inductance estimation is shown in FIG. 3 . In Figure 3, I _{Li_set} is the set value of the current flowing through the receiving coil, and the expression of the estimated value I _{Li_es} of I _Li is

The deviation of I _{Li_set} and I _{Li_es} is input into the PI controller, and the output of the PI controller is the input voltage U _m required to eliminate the deviation, and U _m is input into the PWM wave generator as an actuator, and the PWM wave generator adopts the SSPWM method Input the required driving signal into the four MOSFETs of the full-bridge inverter, at this time the input voltage u _in generated by the DC power supply and the full-bridge inverter satisfies

u _in (t)＝U ₁ sinω ₁ t+…+U _m sinω _m t (10);

In the formula, t is time. With the adjustment of U _m , the current I _Li flowing through the receiving coil will be adjusted accordingly to approach the set value I _{Li_set} , realizing multi-constant current output.

DC voltage source, inverter, primary side resonance compensation network, transmitting coil, receiving coil, secondary side resonance compensation network, rectifier, filter capacitor, charging load, primary side main capacitor, primary side compensation capacitor, primary side compensation inductor, secondary Side main capacitor, secondary side compensation capacitor, secondary side compensation inductor, sampling module, Fourier transform module, mutual inductance estimation module, PI controller, PWM wave generator, full bridge inverter, current sensor, etc. The components and functional modules in the technology, or adopt the components and functional modules in the prior art and use conventional technical means to construct.

The above-described embodiments are only used to illustrate the technical ideas and characteristics of the present invention, and its purpose is to enable those skilled in the art to understand the content of the present invention and implement it accordingly. The present invention cannot be limited only by this embodiment. The scope of the patent, that is, all equivalent changes or modifications made to the spirit disclosed in the present invention still fall within the scope of the patent 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:

for primary side resonance compensation network at angular frequency of omega _m The reactance of (d);

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:

the secondary side resonance compensation network for the ith secondary side system has an angular frequency of omega _m The reactance of (d);

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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