CN118457970B - A current doubler controller and control method for wireless charging system of unmanned aerial vehicle - Google Patents
A current doubler controller and control method for wireless charging system of unmanned aerial vehicle Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J7/00—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J7/02—Circuit arrangements for charging or depolarising batteries or for supplying loads from batteries for charging batteries from AC mains by converters
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U50/00—Propulsion; Power supply
- B64U50/30—Supply or distribution of electrical power
- B64U50/34—In-flight charging
- B64U50/35—In-flight charging by wireless transmission, e.g. by induction
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64U—UNMANNED AERIAL VEHICLES [UAV]; EQUIPMENT THEREFOR
- B64U50/00—Propulsion; Power supply
- B64U50/30—Supply or distribution of electrical power
- B64U50/37—Charging when not in flight
- B64U50/38—Charging when not in flight by wireless transmission
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J50/00—Circuit arrangements or systems for wireless supply or distribution of electric power
- H02J50/10—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling
- H02J50/12—Circuit arrangements or systems for wireless supply or distribution of electric power using inductive coupling of the resonant type
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/14—Arrangements for reducing ripples from DC input or output
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
- H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
- H02M7/06—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes without control electrode or semiconductor devices without control electrode
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M7/00—Conversion of AC power input into DC power output; Conversion of DC power input into AC power output
- H02M7/02—Conversion of AC power input into DC power output without possibility of reversal
- H02M7/04—Conversion of AC power input into DC power output without possibility of reversal by static converters
- H02M7/12—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
- H02M7/21—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
- H02M7/217—Conversion of AC power input into DC power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2207/00—Indexing scheme relating to details of circuit arrangements for charging or depolarising batteries or for supplying loads from batteries
- H02J2207/20—Charging or discharging characterised by the power electronics converter
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- Combustion & Propulsion (AREA)
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Abstract
The invention discloses a current doubling controller and a control method for a wireless charging system of an unmanned aerial vehicle, wherein the current doubling controller comprises: resonant cavity, first rectification branch road, second rectification branch road, first control module, second control module and output circuit for carry out rectification and power regulation to unmanned aerial vehicle wireless charging system secondary side, make the pick-up current satisfy the output demand. The control circuit controls the first switching tube and the second switching tube to be opened normally to control the full power operation of the double-flow controller, or controls the switching frequency and the duty ratio of the first switching tube and the second switching tube to control the output power of the double-flow controller to be adjustable. The current doubler controller has fewer components and has higher efficiency and lower output ripple at high power conditions than a boost controller.
Description
Technical Field
The invention belongs to the technical field of unmanned aerial vehicle wireless charging, and particularly relates to a current doubling controller and a control method for an unmanned aerial vehicle wireless charging system.
Background
IPT (inductive power transfer ) has become increasingly popular because it enables power transfer through an air gap without requiring physical contact. They are therefore immune to dirt, ice, water and chemicals, rendering them environmentally inert and low maintenance. IPT has been used in a variety of applications, from low power applications such as biomedical implants and cell phone charging, to high power applications such as electric vehicles and materials handling.
Figure 1 shows a standard IPT system in which a power supply generates an alternating current, thereby generating a magnetic field. This magnetic field is coupled to the pick-up means (a pick-up coil) and a voltage is induced between it. The sensed voltage is rectified and regulated by the controller. Typically, the pickup is tuned to a resonant frequency to increase the ability to output power.
In drone charging applications, the primary side is typically an elongated wire to which wireless energy extraction is accomplished by a pickup device provided on the drone. The pickup is usually hardly moved laterally and therefore the coupling between the main track and the pickup is usually constant. However, the pick-up device generates a pick-up current I sc that may not meet the output requirements, and this problem is usually solved by using a pick-up controller for secondary side power regulation. There are several types of pickup controllers, more commonly parallel-tuned boost controllers, as shown in FIG. 2. However, when the boost controller is applied to high power, two parallel circuits are required to handle large currents in high power applications, the number of components is large, and the efficiency of the controller is reduced.
Disclosure of Invention
In order to solve the defects in the prior art, the invention provides the current doubling controller for the unmanned aerial vehicle wireless charging system and the control method, which are used for carrying out power adjustment control on the secondary side of the unmanned aerial vehicle wireless charging system, have fewer components than the voltage doubling controller and realize higher efficiency.
The invention adopts the following technical scheme.
A first aspect of the present invention provides a current doubler controller for a wireless charging system for a drone, comprising:
The resonant cavity is used for being coupled to a primary side charging electric wire of the unmanned aerial vehicle for wireless energy taking under the tuned resonant frequency to generate induced voltage and pickup current;
The first rectification branch circuit is connected with one end of the resonant cavity and two ends of the output circuit and is used for rectifying the induced voltage generated by the resonant cavity, changing the alternating voltage into direct voltage and outputting the direct voltage to the output circuit;
the second rectifying branch is connected with the other end of the resonant cavity and two ends of the output circuit and is used for being matched with the first rectifying branch in parallel to rectify the induced voltage;
the first control module is connected with the first rectifying branch and used for controlling whether the current of the first rectifying branch flows to the output circuit or not;
the second control module is connected with the second rectification branch circuit and is used for controlling whether the current of the second rectification branch circuit flows to the output circuit or not, and is matched with the first control module to control the operation mode of the double-flow controller, so that the power of the secondary side of the unmanned aerial vehicle wireless charging system is regulated, and the pickup current meets the output requirement;
And the output circuit is used for stabilizing and outputting the rectified and regulated direct-current voltage.
Preferably, the resonant cavity comprises: the device comprises a pickup device, a parallel tuning capacitor, a first output end and a second output end, wherein the pickup device and the parallel tuning capacitor are in parallel resonance;
The output circuit includes: the circuit comprises a filter capacitor, a load, a first circuit end and a second circuit end, wherein the filter capacitor and the load are connected in parallel.
Preferably, the first rectifying branch comprises: the first diode, the first inductor and the third diode are sequentially connected in series between the first circuit end and the second circuit end of the output circuit, and the common end of the first diode and the first inductor is connected with the first output end of the unmanned aerial vehicle wireless pickup device; the first diode and the third diode are used for controlling the current of the first rectifying branch to flow unidirectionally, and the first inductor is used for storing energy or consuming the energy to supply power for a load according to the input power of the resonant cavity received by the control signal of the first control module;
The second rectifying branch includes: the forward second diode, the second inductor and the forward fourth diode are sequentially connected in series between the first circuit end and the second circuit end of the output circuit, and the common end of the second diode and the second inductor is connected with the second output end of the unmanned aerial vehicle wireless pickup device; the second diode and the fourth diode are used for controlling the current of the second rectifying branch to flow unidirectionally, and the second inductor is used for storing energy or consuming the energy to supply power for a load according to the input power of the resonant cavity received by the control signal of the second control module;
The first control module includes: the source electrode of the first switch tube is connected with the first circuit end of the output circuit, the drain electrode of the first switch tube is connected with the common end of the first inductor and the third diode, and the grid electrode of the first switch tube is connected with the control circuit; the first switching tube is used for receiving a control signal of the control circuit to be turned on or turned off so as to control a path of the first inductance current;
The second control module includes: the source electrode of the second switch tube is connected with the first circuit end of the output circuit, the drain electrode of the second switch tube is connected with the common end of the second inductor and the fourth diode, and the grid electrode of the second switch tube is connected with the control circuit; the second switching tube is used for receiving a control signal of the control circuit to be turned on or turned off so as to control a path of the second inductance current.
A second aspect of the present invention provides a control method for a wireless charging system of a drone, using a current doubling controller according to the first aspect of the present invention to control the wireless charging system of the drone, comprising the steps of:
step 1, selecting a control mode, including a full-power operation mode and a switch control mode, and executing step 2 and step 3 respectively;
Step 2, the control circuit controls the first switching tube and the second switching tube to be normally open, so that the current doubling controller operates at full power, the inductor is designed to ensure that the inductor current is always continuous, and the step is ended;
And 3, controlling the switching frequency and the duty ratio of the first switching tube and the second switching tube to enable the output power of the current doubling controller to be adjustable.
Preferably, in the full power mode of operation, the first inductance is designed such that the current of the first inductance is always continuous based on the following formula:
，
，
，
，
Wherein:
representing an output voltage of the output circuit;
a peak value representing a resonance voltage of the unmanned aerial vehicle wireless pickup device;
v LDC1 denotes the first inductor voltage;
i LDC1 denotes a first inductor current;
a first inductor current value representing an initial time;
The inductance value of the first inductor;
Representing the resonant angular frequency;
t represents the current time;
T represents the period of the resonance voltage.
Preferably, the second inductor has the same inductance value as the first inductor.
Preferably, in the full power mode of operation, the rate of change of the first inductor current over a period is expressed as follows,
，
Wherein:
Representing the rate of change of the first inductor current in one cycle;
f is the resonant frequency.
Preferably, in the switch control mode, the switching frequencies of the first switching tube and the second switching tube are set to be the same and higher than the resonance frequency, and the first switching tube and the second switching tube are set to be 180 degrees inverted.
Preferably, the duty cycle Ds of the first switching tube and the second switching tube is selected according to the following formula:
，
，
Wherein:
representing an output voltage of the output circuit;
a peak value representing a resonance voltage of the unmanned aerial vehicle wireless pickup device;
d s is the duty cycle of the first switching tube and the second switching tube;
representing the resonant angular frequency.
Preferably, in the switching control mode, the rate of change of the first inductor current in one period is expressed as follows,
，
Wherein:
Representing the rate of change of the first inductor current in one cycle;
The inductance value of the first inductor;
f is the resonant frequency;
T represents the period of the resonance voltage.
Compared with the prior art, the invention has the beneficial effects that at least:
(1) The current doubler controller has fewer components than the boost controller.
(2) Under high power conditions, the current doubler controller provided by the invention has higher efficiency and lower output ripple.
Drawings
Fig. 1 is a block diagram of a typical IPT system provided in the background of the invention;
FIG. 2 is a circuit diagram of a conventional IPT boost controller provided in the background of the invention;
Fig. 3 is a circuit diagram of a current doubler controller for a wireless charging system of a drone according to an embodiment of the present invention;
FIG. 4 is a waveform and current pattern for a current doubler controller in a full power mode of operation provided by an embodiment of the present invention;
FIG. 5 is a waveform and current pattern of a current doubler controller in a switch control mode provided by an embodiment of the present invention;
FIG. 6 is a graph comparing simulation efficiencies of a current doubler controller and a boost controller provided by an embodiment of the present invention;
FIG. 7 is a waveform diagram of a measurement of a prototype of a current doubler controller in a full power mode of operation provided by an example application of the present invention;
Fig. 8 is a waveform diagram showing the operation of the prototype of the current doubler controller according to the application example of the present invention in the switch control mode.
In the figure: 1. a resonant cavity; 11. a first output terminal; 12. a second output terminal; 2. an output circuit; 21. a first circuit terminal; 22. a second circuit terminal; 3. a control circuit; l DC1, a first inductor; l DC2, a second inductor; d 1, a first diode; d 2, a second diode; d 3, a third diode; d 4, fourth diode; d 5, a fifth diode; s 1, a first switching tube; s 2, a second switching tube; l 2, a pickup device; c 2, connecting a tuning capacitor in parallel; c DC, a filter capacitor; r L, load.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the technical solutions of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application. The described embodiments of the application are only some, but not all, embodiments of the application. All other embodiments, which can be made by those skilled in the art without making any inventive effort, are within the scope of the present application.
As shown in fig. 3, embodiment 1 of the present invention provides a current doubler controller for a wireless charging system of a drone, including:
The resonant cavity 1 is used for being coupled to a primary side charging electric wire of the unmanned aerial vehicle for wireless energy taking under the tuned resonant frequency to generate induced voltage and pickup current;
The first rectification branch is connected with one end of the resonant cavity 1 and two ends of the output circuit 2 and is used for rectifying the induced voltage generated by the resonant cavity 1, changing the alternating voltage into direct voltage and outputting the direct voltage to the output circuit 2;
the second rectification branch is connected with the other end of the resonant cavity 1 and two ends of the output circuit 2 and is used for being matched with the first rectification branch in parallel to rectify the induced voltage;
The first control module is connected with the first rectification branch and is used for controlling whether the current of the first rectification branch flows to the output circuit 2 or not;
the second control module is connected with the second rectification branch circuit and is used for controlling whether the current of the second rectification branch circuit flows to the output circuit 2 or not, and is matched with the first control module to control the operation mode of the double-flow controller, so that the power of the secondary side of the unmanned aerial vehicle wireless charging system is regulated, and the pickup current meets the output requirement;
and the output circuit 2 is used for stabilizing and outputting the rectified and regulated direct-current voltage.
Preferably, the resonant cavity 1 comprises: the device comprises a pickup device L 2, a parallel tuning capacitor C 2, a first output end 11 and a second output end 12, wherein the pickup device L 2 and the parallel tuning capacitor C 2 are in parallel resonance, mutual inductance M exists between the pickup device L 2 and a primary side charging wire of the unmanned aerial vehicle, and resonance current I 2 flows into a first rectifying branch through the first output end 11 and flows back from the second rectifying branch through the second output end 12;
The output circuit 2 includes: the filter capacitor C DC, the load R L, the first circuit terminal 21 and the second circuit terminal 22 are connected in parallel, and the filter capacitor C DC and the load R L are connected in parallel.
Further preferably, the first rectifying branch includes: the first forward diode D 1, the first inductor L DC1 and the third forward diode D 3 are sequentially connected in series between the first circuit end 21 and the second circuit end 22 of the output circuit 2, and the common end of the first diode D 1 and the first inductor L DC1 is connected with the first output end 11 of the unmanned aerial vehicle wireless pickup device; the first diode D 1 and the third diode D 3 are used for controlling the current of the first rectifying branch to flow unidirectionally, and the first inductor L DC1 is used for receiving the input power of the resonant cavity 1 to store energy or consuming the energy to supply power to a load according to a control signal of the first control module;
The second rectifying branch includes: the forward second diode D 2, the second inductor L DC2 and the forward fourth diode D 4 are sequentially connected in series between the first circuit end 21 and the second circuit end 22 of the output circuit 2, and the common end of the second diode D 2 and the second inductor L DC2 is connected with the second output end 12 of the unmanned aerial vehicle wireless pickup device; the second diode D 2 and the fourth diode D 4 are used for controlling the current of the second rectifying branch to flow unidirectionally, and the second inductor L DC2 is used for receiving the input power of the resonant cavity 1 to store energy or consuming the energy to supply power to the load according to the control signal of the second control module;
the first control module includes: a source electrode of the first switching tube S 1 and a first switching control part of the control circuit 3 are connected with a first circuit end 21 of the output circuit, a drain electrode of the first switching tube S 1 is connected with a common end of the first inductor L DC1 and the third diode D 3, and a grid electrode of the first switching tube S 1 is connected with the control circuit 3; the first switch tube S 1 is used for receiving a control signal of the control circuit 3 to be turned on or turned off so as to control a path of the first inductance current;
The second control module includes: a source electrode of the second switching tube S 2 and a second switching control part of the control circuit 3 are connected with the first circuit end 21 of the output circuit, a drain electrode of the second switching tube S 2 is connected with a common end of the second inductor L DC2 and the fourth diode D 4, and a grid electrode of the second switching tube S 2 is connected with the control circuit 3; the second switching tube S 2 is configured to receive a control signal from the control circuit 3, and turn on or off, so as to control a path of the second inductor current.
It will be appreciated that the circuit shown in fig. 3 has double the number of switches, inductors and circulating diodes (third diode D 3 and fourth diode D 4) as compared to the boost controller. However, these components only require half of the current rating in the boost controller. The number of components required in the current-doubler controller is smaller than the boost controller at high power.
Embodiment 2 of the present invention provides a method for controlling a wireless charging system of a drone using a multiplier controller as described in embodiment 1, comprising the steps of:
step 1, selecting a control mode, including a full-power operation mode and a switch control mode, and executing step 2 and step 3 respectively;
Step 2, the control circuit 3 controls the first switching tube S 1 and the second switching tube S 2 to be normally opened, so that the current doubling controller operates at full power, the inductor is designed to ensure that the inductor current is always continuous, and the step is ended;
at full power operation, both the first switching tube S 1 and the second switching tube S 2 are open and therefore can be ignored. The inductor is assumed to be large enough to ensure continuous conduction under all practical loading conditions. The current doubler controller without switching regulation operates as a push-pull reverse resonator. Output voltage of current-doubling controller in full power operation Expressed in terms of the following formula,
（1）
Wherein:
the peak value of the resonance voltage V 2 of the unmanned aerial vehicle wireless pickup device is indicated.
For simplicity, the following analysis of the current doubler controller will be based on the first inductance L DC1, but is not intended to limit the scope of the invention. It will be appreciated that the derivation can be readily applied to the second inductance L DC2 with a 180 ° phase shift.
The system operation waveform of the current doubler controller operating at full power is shown in fig. 4 (a), and the resonant voltage V 2 of the pick-up device is a sine wave. Assuming output voltageBeing constant, the diodes are ideal, the voltage drop between the diodes is negligible, the first inductor voltage V LDC1 is expressed as follows,
（2）
Wherein:
t represents the current time;
t represents the period of V2;
representing the resonant angular frequency.
When 0< t < T/2, the resonance voltage V 2 is positive, and the current generated by the resonant cavity 1 passes through the first inductance L DC1 to the output circuit 2, as indicated by the solid arrow in (b) of FIG. 4. According to equation (2), the first inductor voltage V LDC1 has not only a DC componentAlso contains sinusoidal componentsSince the current is not constant, the first inductor current I LDC1 does not rise linearly as in a standard current-doubler circuit.
V 2 is less than at t=0V LDC1 is negative, which results in the first inductor current I LDC1 reaching a valley before increasing. This phenomenon reappears before T/2, causing inductor current I LDC1 to peak before it drops.
The first inductor current I LDC1 of the energy storage phase (0 < t/2) is represented by the following formula (3),
（3）
Wherein:
a first inductor current value representing an initial time;
Is the inductance value of the first inductor.
The maximum and minimum values of I LDC1 occur at V LDC1 =0 and V 2 =at steady stateThe occurrence times corresponding to these points are expressed by the following formula (4),
（4）
Wherein:
representing an output voltage of the output circuit;
A peak value of the resonance voltage V2 of the unmanned aerial vehicle wireless pickup device is represented.
Preferably, based on equations (1) - (4), the inductance may be designed such that the inductor current is always continuous.
Further preferably, the first inductance L DC1 and the second inductance L DC2 have the same inductance value.
When T/2< T < T, the resonant voltage V 2 is negative, the first diode D 1 is forward biased, the first inductor L DC1 has no input voltage, and instead the stored energy is dissipated to the load. The current direction of I LDC1 at this time is shown in FIG. 4 (c), due toAs a constant, I LDC1 decreases at a constant rate.
The first inductor current I LDC1 of the energy consumption phase (T/2 < T) is expressed as the following formula (5),
（5）
Wherein:
the first inductor current magnitude at t=t/2 is indicated.
According to the formulas (1), (3) and (5), the change rate of I LDC1 in one period in the full-power operation mode is obtained as shown in the formula (6),
（6）
Wherein:
f is the resonant frequency.
It will be appreciated that I LDC1 will have less ripple at higher resonant frequencies, since the rate of change is inversely proportional to the resonant frequency. This makes the current doubler controller more suitable for higher resonant frequency applications to provide lower inductor current ripple, as well as smaller inductors.
With the current doubler controller tuned in parallel, the resonant cavity 1 is equivalent to a current source whose output is the pick-up current I sc. Thus, the average currents of I LDC1 and I LDC2 are shown in formula (7), and I o is shown in formula (8).
（7）
（8）
Wherein:
rms represents the effective value.
And 3, controlling the switching frequency and the duty ratio of the first switching tube S 1 and the second switching tube S 2 to enable the output power of the current doubling controller to be adjustable.
The method of controlling the output power of the current doubler controller is similar to that of the boost controller by adjusting the switching frequency and duty cycle to regulate the power of the load.
Preferably, during the output adjustment, the switching frequency of the first switching tube S 1 and the second switching tube S 2 is set to be the same and higher than the resonant frequency, and the first switching tube S 1 and the second switching tube S 2 have 180 ° phase opposition, and the waveform of the current doubler controller provides a smoother output current as shown in fig. 5 (a).
During the period in fig. 5 (a) when the switches are all off, the resonant cavity 1 is in a short-circuited state, and no power is transferred to the load;
During time t 1 of fig. 5 (a), V 2 is positive, the first switching tube S 1 is opened, and the resonant current I 2 flows back through the first switching tube S 1 and through the second diode D 2 without flowing to the load, as shown in fig. 5 (b). In this embodiment, energy is stored in a first inductance L DC1, while a second inductance L DC2 provides power to the load. Since the load on the first inductor L DC1 branch is less, I LDC1 increases at a faster rate;
In the period t 2 of fig. 5 (a), V 2 is positive, the second switching tube S 2 is turned on, the resonant current I 2 flows to the output circuit 2, and the current in the second inductor L DC2 sequentially passes through the second switching tube S 2 and the second diode D 2, as shown in fig. 5 (c). Because of the low state resistance of the second switching tube S 2, the voltage drop across the second diode D 2 is small, the attenuation of I LDC2 is small, and only a short time is negligible.
Although the resonant frequency and the switching frequency are different, the variation due to switching can be averaged to simplify the calculation. In addition, V 2 approximates a sine wave.And V LDC1 during switching adjustment, expressed as equations (9) and (10), respectively,
（9）
（10）
Wherein:
D s is the duty cycle of the first switching tube S 1 and the second switching tube S 2.
Preferably, the relation between the duty cycle of the switch and the power is obtained according to the formula (9), and it is known that a maximum transmission power duty cycle exists, but only the transmission power is considered, so that the output current ripple is possibly overlarge; according to equation (10), the lower the output current ripple, the higher Ds, the better the balance between the two, and an optimal duty cycle is chosen.
According to the formulas (9) and (10), the change rate of I LDC1 in one period in the switching control mode is obtained as shown in the formula (11),
（11）
It will be appreciated that based on the above analysis of inductor current for the time periods t 1 and t 2, during switching regulation, inductor current is a function of (1-Ds) and increases or decreases very slowly, so inductor current ripple is low.
Examples of application of the invention are described below with reference to the accompanying drawings: the following examples give detailed embodiments and processes on the premise of the technical scheme of the present invention, and further verify the beneficial technical effects of the present invention by comparing the current doubling controller of the present invention with the conventional voltage boosting controller, but the scope of protection of the present invention is not limited to the following application examples.
The current doubler controller of the present invention is a parallel tuned pick-up controller that needs to be compared to a conventional boost controller to evaluate its capability, the comparison comprising: component requirements, output ripple and efficiency.
Example 1 with double current controller, double current and boost controller in low and high power scenarios the number of components required versus results are shown in table 1, with the current rating for the current number of double components of the double current controller being only half that of the boost controller.
Table 1 number comparison
When the current doubler controller is used in a low power scenario, the first inductor L DC1 or the second inductor L DC2 is used as an inductor component, the first switch tube S 1 or the second switch tube S 2 is used as a switch component, the first diode D 1 or the second diode D 2 is used as a circulating diode component, the third diode D 3 or the fourth diode D 4 is used as a rectifying diode component, the current required by the inductor component, the switch component and the circulating diode component is half of the current rating of the corresponding components in the boost controller which is the same as the low power scenario, the number of the inductor component, the switch component and the circulating diode component is 2 times that of the corresponding components in the boost controller, and the number of the rectifying diode components is half that of the corresponding components in the boost controller.
When the current doubler controller is used in a high power scenario, the first inductor L DC1 or the second inductor L DC2 is used as an inductor component, the first switching tube S 1 or the second switching tube S 2 is used as a switching component, the first diode D 1 or the second diode D 2 is used as a circulating diode component, the third diode D 3 or the fourth diode D 4 is used as a rectifying diode component, the current required by the inductor component is half of the current rating of the corresponding component in the boost controller which is the same as the low power scenario, the number of the inductor components is 2 times of the number of the corresponding component in the boost controller, and the number of the switching tube components and the circulating diode components are the same as the number of the corresponding component in the boost controller, and the number of the rectifying diode components is half of the corresponding component in the boost controller.
At low power, the system current is very low and parallel semiconductor devices are not required. Thus, the current doubler controller for low power scenarios has a greater number of components. However, the switch, the loop diode and the inductor only need to boost half of the rated current of the controller. Alternative components with better ratings may be used to reduce cost and increase the efficiency of current flow doublers. In addition, the double current transformer has lower loss than the boost controller due to the reduction of rectifier diodes and direct current inductors for rectification.
For high power applications, two semiconductor devices are required in the boost controller to handle the large currents and share losses, the number of components of the boost controller being smaller than the boost controller, as shown in table 1. The number of semiconductor devices (except rectifier diodes) remains unchanged at the current-doubler controllers because they are half the rated power. Based on this, a high power scenario of a current doubler controller with fewer four rectifier diodes, and an additional inductance, is an advantageous option.
The number of turns of the secondary magnetic amplifier (i.e., the pick-up device L 2) of the current doubles that of the boost controller to provide the same output current. This will double the open circuit voltage V oc of the coil, I sc, and the coil resistance will double. However, since the resonant current I 2 is lower, the winding loss will be reduced because it is a function of the lower I sc.
The tuning capacitor of the current doubler controller must handle higher cavity voltages, using capacitors with higher voltage capability or series capacitors. The resonant capacitor group can be composed of two groups of tuning capacitors with the same capacitance value, and the tuning capacitors are respectively connected in series and in parallel and used for a current doubling controller and a boost controller so as to achieve the required capacitance, voltage and rated current.
Example 2a simulation of a current doubler controller and a boost controller was performed using SPLEC, the circuit connections shown in fig. 3 and 2, respectively, and the components and simulation parameters shown in table 2, respectively.
Table 2 simulation parameters
In table 2, L 1 represents an inductance coil for equivalently replacing a primary side wire when the unmanned aerial vehicle is charged during simulation, k represents a coupling coefficient of the coupling mechanism, V oc represents an open-circuit voltage of the pickup device, R LDC1 represents a resistance value of L DC1, R LDC2 represents a resistance value of L DC2, and R LDC represents a resistance value of L DC.
To provide a fair comparison, both pickups are set to output the same voltage and current. The pick-up coils of the current doubler controller and the boost controller are based on 8-turn and 4-turn loop S-pick-up, respectively, to ensure that both controllers provide the same output current. The primary side circuit consists of an LCL inverter that provides 25A of track current at 21.25kHz through a 4 turn main circuit.
Two controllers regulate output voltageTo 300V to provide a 5kW output. As a result of the specific simulation, the ripple of the output (voltage and current) of the current doubler controller and the boost controller was 0.653% and 1.094%, respectively. Fig. 6 is a graph comparing the efficiency of the current doubler controller and the boost controller (including the inverter) at different output powers P o, at output power P o =5 kW, with efficiencies of 95.4% and 93.9%, respectively. It can be seen that the current doubler controller proposed by the present invention has higher efficiency and lower output ripple.
It is noted that the number of switching transistors and diodes is the same in the current doubler controller and the boost controller. Considering that current-doubler controller components only require half of the boost converter current rating, components with better characteristics may be used to increase the efficiency of the controller.
Example 3 an existing current-doubler controller prototype was built and experimental verification was performed on the simulation results, with system parameters as shown in table 3. The main power supply is an H-bridge LCL inverter (comprising an inductor) and generates high-voltage current of 25A and 21.25kHz through a 4-turn main rail L. The pick-up for the current doubler controller is a parallel tuned 8 turn annular core S-shaped pick-up.
TABLE 3 experimental setup parameters
Each dc inductance in the current-doubler controller uses two PM87 cores to reach about 550 muh. This value is selected by equations (3) and (4) to ensure that the current in the inductor is continuous. The current doubler controller is arranged to regulate the output voltageTo 300V.
Fig. 7 shows the output waveforms of the current doubler controller without switching regulation. The electronic load operates in constant voltage mode and outputs a voltageLimited to 100V. This requires the controller to operate in full power mode without the need to adjust the switching tube. The waveform is similar to the waveform previously shown in fig. 4. I LDC1 and I LDC2 here are 13.1A and 12.72A, respectively. The slight difference in inductor current is due to small variations in inductance and resistance of the inductor. The output current is 25.52A, and the current doubling is realized.
FIG. 8 shows the regulated output voltageWaveform diagram to 300V, 5kW output power of the current doubler controller. The average current of inductor current I LDC1 is 12.6A, similar to the analog waveform previously shown in fig. 5.
When 5kW of output power is provided, the duty cycle of the current doubler controller is approximately 32.8%. At this time, the measurement efficiency of the current doubler controller was 94.4%. The maximum difference between the simulation efficiency and the actual measurement efficiency is 1%, which shows that the actual result and the simulation result are well matched. From the results obtained, the current-doubler controller is equivalent to the boost controller, and is an alternative controller.
In summary, the current doubler controller for the unmanned aerial vehicle wireless charging system provided by the invention consists of two inductors, four diodes and two switching tubes, and has fewer components compared with the voltage doubler controller. The controller regulates the output power by short-circuit control of two switches that operate in antiphase to reduce the output ripple. The present invention also simulates current and boost controllers with efficiencies of 95.4% and 93.9% at 5kW, respectively. The output ripple of the current doubler controller of the present invention is low, while the magnitude of the increase is 0.65%. The invention also establishes the prior current double flow controller prototype, the measurement efficiency is 94.4 percent, and the invention is well matched with the simulation result. From the results obtained, the current doubler controller is an alternative to the boost controller, has fewer components than the boost controller, and enables higher transmission efficiency.
Compared with the prior art, the invention has the beneficial effects that at least:
(1) The current doubler controller has fewer components than the boost controller.
(2) Under high power conditions, the current doubler controller provided by the invention has higher efficiency and lower output ripple.
The present disclosure may be a system, method, and/or computer program product. The computer program product may include a computer readable storage medium having computer readable program instructions embodied thereon for causing a processor to implement aspects of the present disclosure.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the same, and although the present invention has been described in detail with reference to the above embodiments, it should be understood by those skilled in the art that: modifications and equivalents may be made to the specific embodiments of the invention without departing from the spirit and scope of the invention, which is intended to be covered by the claims.
Claims (8)
1. A current doubler controller for a wireless charging system of an unmanned aerial vehicle, comprising:
the resonant cavity (1) is used for being coupled to a primary side charging electric wire of the unmanned aerial vehicle for wireless energy taking under the tuned resonant frequency to generate induced voltage and pickup current;
The resonant cavity (1) comprises: a pick-up device (L 2), a parallel tuning capacitor (C 2), a first output (11) and a second output (12), the pick-up device (L 2) and the parallel tuning capacitor (C 2) resonating in parallel;
the first rectifying branch is connected with one end of the resonant cavity (1) and two ends of the output circuit (2) and is used for rectifying the induced voltage generated by the resonant cavity (1) from alternating voltage to direct voltage and outputting the direct voltage to the output circuit (2);
The first rectifying branch includes: the first diode (D 1), the first inductor (L DC1) and the third diode (D 3) are sequentially connected in series between a first circuit end (21) and a second circuit end (22) of the output circuit (2), and the common end of the first diode (D 1) and the first inductor (L DC1) is connected with a first output end (11) of the unmanned aerial vehicle wireless pickup device; the first diode (D 1) and the third diode (D 3) are used for controlling the current of the first rectifying branch to flow unidirectionally, and the first inductor (L DC1) is used for receiving the input power of the resonant cavity (1) to store energy or consuming the energy to supply power for a load according to a control signal of the first control module;
the second rectifying branch is connected with the other end of the resonant cavity (1) and two ends of the output circuit (2) and is used for being matched with the first rectifying branch in parallel to rectify the induced voltage;
The second rectifying branch includes: the forward second diode (D 2), the second inductor (L DC2) and the forward fourth diode (D 4) are sequentially connected in series between a first circuit end (21) and a second circuit end (22) of the output circuit (2), and the common end of the second diode (D 2) and the second inductor (L DC2) is connected with a second output end (12) of the unmanned aerial vehicle wireless pickup device; the second diode (D 2) and the fourth diode (D 4) are used for controlling the current of the second rectifying branch to flow unidirectionally, and the second inductor (L DC2) is used for receiving the input power of the resonant cavity (1) to store energy or consuming the energy to supply power for a load according to a control signal of the second control module;
The first control module is connected with the first rectifying branch and is used for controlling whether the current of the first rectifying branch flows to the output circuit (2);
the first control module includes: a source electrode of the first switching tube (S 1) is connected with a first circuit end (21) of the output circuit (2), a drain electrode of the first switching tube (S 1) is connected with a common end of the first inductor (L DC1) and the third diode (D 3), and a grid electrode of the first switching tube is connected with the control circuit (3); the first switching tube (S 1) is used for receiving a control signal of the control circuit (3) to be turned on or off so as to control a path of the first inductance current;
The second control module is connected with the second rectification branch circuit and is used for controlling whether the current of the second rectification branch circuit flows to the output circuit (2), and is matched with the first control module to control the operation mode of the double-flow controller, so that the secondary side of the wireless charging system of the unmanned aerial vehicle is subjected to power adjustment, and the pickup current meets the output requirement;
The second control module includes: a source electrode of the second switching tube (S 2) is connected with a first circuit end (21) of the output circuit (2), a drain electrode of the second switching tube (S 2) is connected with a common end of the second inductor (L DC2) and the fourth diode (D 4), and a grid electrode of the second switching tube is connected with the control circuit (3); the second switching tube (S 2) is used for receiving a control signal of the control circuit (3) to be turned on or off so as to control a path of a second inductance current;
the output circuit (2) is used for stabilizing and outputting the rectified and regulated direct-current voltage;
The output circuit (2) includes: the circuit comprises a filter capacitor (C DC), a load (R L), a first circuit end (21) and a second circuit end (22), wherein the filter capacitor (C DC) and the load (R L) are connected in parallel.
2. A control method for a wireless charging system of a drone, using the current doubler controller of claim 1, comprising the steps of:
step 1, selecting a control mode, including a full-power operation mode and a switch control mode, and executing step 2 and step 3 respectively;
Step 2, a control circuit (3) controls a first switching tube (S 1) and a second switching tube (S 2) to be normally opened, so that the current doubling controller operates at full power, the inductor is designed to ensure that the inductor current is always continuous, and the step is ended;
And 3, controlling the switching frequency and the duty ratio of the first switching tube (S 1) and the second switching tube (S 2) to enable the output power of the current doubling controller to be adjustable.
3. A control method for a wireless charging system for a drone according to claim 2, wherein:
In the full power mode of operation, the first inductance (L DC1) is designed such that the current of the first inductance (L DC1) is always continuous based on the following formula:
Wherein:
representing an output voltage of the output circuit;
a peak value representing a resonance voltage of the unmanned aerial vehicle wireless pickup device;
v LDC1 denotes the first inductor voltage;
i LDC1 denotes a first inductor current;
a first inductor current value representing an initial time;
The inductance value of the first inductor;
Representing the resonant angular frequency;
t represents the current time;
T represents the period of the resonance voltage.
4. A control method for a wireless charging system for a drone according to claim 3, wherein:
The second inductance (L DC2) has the same inductance value as the first inductance (L DC1).
5. A control method for a wireless charging system for a drone according to claim 3, wherein:
In the full power mode of operation, the rate of change of the first inductor current over a period is expressed as follows,
Wherein:
Representing the rate of change of the first inductor current in one cycle;
f is the resonant frequency.
6. A control method for a wireless charging system for a drone according to claim 2, wherein:
In a switching control mode, the switching frequencies of the first switching tube (S 1) and the second switching tube (S 2) are set to be the same and higher than the resonant frequency, and the first switching tube (S 1) and the second switching tube (S 2) are set to be 180 degrees in opposite phases.
7. A control method for a wireless charging system for a drone according to claim 2, wherein:
The duty cycle D s of the first switching tube (S 1) and the second switching tube (S 2) is selected according to the following formula:
Wherein:
representing an output voltage of the output circuit;
a peak value representing a resonance voltage of the unmanned aerial vehicle wireless pickup device;
d s is the duty cycle of the first switching tube (S 1) and the second switching tube (S 2);
representing the resonant angular frequency.
8. The control method for a wireless charging system of a drone of claim 7, wherein:
in the switching control mode, the rate of change of the first inductor current in one period is expressed as follows,
Wherein:
Representing the rate of change of the first inductor current in one cycle;
The inductance value of the first inductor;
f is the resonant frequency;
T represents the period of the resonance voltage.
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