Anti-offset wireless power transmission device based on power-free fractional order capacitor

Abstract

The application discloses an anti-deviation wireless power transmission device based on a power-free fractional order capacitor, which comprises a transmitting side circuit, a receiving side circuit and a digital processor; the transmitting side circuit comprises a high-frequency inverter, a fractional order capacitor circuit and a transmitting coil; the input end of the high-frequency inverter is connected with an input power supply, and the output end of the high-frequency inverter is connected with the fractional order capacitor circuit and the transmitting coil respectively; the receiving side circuit comprises a receiving coil, a secondary side compensation unit, a rectifier circuit and a load; the receiving coil is wirelessly connected with the transmitting coil, and the receiving coil, the secondary side compensation unit, the rectifier circuit and the load are sequentially connected; the digital processor receives output voltage information of the load, compares the output voltage information with a reference voltage, outputs a phase shift angle, drives a switch tube in the fractional order capacitor circuit according to the phase shift angle and a duty cycle, and stops until the output voltage is constant. The application applies the fractional order capacitor to the wireless power transmission device, and realizes constant voltage output under coil deviation and load variation.

Description

Technical Field

[0001] This invention relates to the field of wireless power transmission, and in particular to an anti-offset wireless power transmission device based on a power-free fractional-order capacitor. Background Technology

[0002] Wireless Power Transmission (WPT), also known as contactless power transfer, refers to the transmission of electrical energy wirelessly by converting it into electromagnetic waves at the transmitting end, and then collecting and converting that energy back into electrical energy at the receiving end. Compared to traditional wired power supply methods, wireless power transmission technology has significant advantages in certain specific situations (such as environments like walls, underwater, or living organisms) because these situations involve higher construction complexity and greater demand for flexible equipment charging. In these cases, wireless power transmission technology not only effectively solves the complex electrical wiring problems of traditional wired power supply methods, but also reduces mechanical switching operations, improves power supply reliability, reduces the consumption of physical consumables, and shortens the construction cycle.

[0003] With the rapid development of new energy technologies, loads are increasingly demanding higher precision in power supply, making more efficient, convenient, and stable power supply methods a research hotspot. This has led to the standardization of charging conditions, driving the development of wireless power transfer technology in terms of power supply stability, particularly in achieving constant voltage, constant current, and constant power modes. However, due to distance variations and the influence of system parasitic parameters, WPT systems often struggle to maintain a controllable constant output in topology design. With continuous technological advancements, more and more researchers are dedicated to achieving constant voltage output in wireless power transfer using various techniques. Traditional methods, such as switched inductors or switched capacitors, typically require additional closed-loop control and sampling circuits, and their control processes are complex, with limited adjustment ranges, making it difficult to achieve wide-range output regulation. Therefore, introducing components with wider impedance regulation capabilities into WPT systems has become a key challenge in solving the system's output regulation range and improving its robustness. Solving this problem is crucial for promoting the development of controllable rectified wireless power transfer technology.

[0004] Fractional circuits have been studied in many fields, and fractional components have attracted attention due to their memory characteristics, but their application in wireless power transmission systems is still in its infancy. Summary of the Invention

[0005] The main objective of this invention is to overcome the aforementioned deficiencies in the prior art and propose an anti-offset wireless power transmission device based on a power-free fractional capacitor. The device provides capacitive impedance through an adjustable fractional capacitor, maintains a constant output voltage by changing the phase shift angle after offset, and adjusts the phase relationship between the input voltage and input current by controlling the phase shift angle to achieve soft switching operation during charging.

[0006] The present invention adopts the following technical solution:

[0007] An anti-offset wireless power transmission device based on a power-free fractional capacitor includes: a transmitter-side circuit, a receiver-side circuit, and a digital processor;

[0008] The transmitting side circuit includes a high-frequency inverter, a fractional capacitor circuit, and a transmitting coil; the input terminal of the high-frequency inverter is connected to the input power supply, and the output terminal of the high-frequency inverter is connected to the fractional capacitor circuit and the transmitting coil, respectively.

[0009] The receiving-side circuit includes a receiving coil, a secondary-side compensation unit, a rectifier circuit, and a load; the receiving coil is wirelessly connected to the transmitting coil, and the receiving coil, the secondary-side compensation unit, the rectifier circuit, and the load are connected in sequence.

[0010] The digital processor receives the output voltage information of the load, compares it with the reference voltage, outputs a phase shift angle, and the PWM generator drives the switching transistors in the fractional capacitor circuit according to the phase shift angle and duty cycle until the output voltage is constant.

[0011] Preferably, the midpoint of one bridge arm of the high-frequency inverter is connected to one end of a fractional capacitor, and the other end of the fractional capacitor is connected to the transmitting coil L. p One end is connected to the transmitting coil L. p The other end is connected to the parasitic resistance R p One end is connected, parasitic resistance R p The other end is connected to the midpoint of the other arm of the high-frequency inverter, forming a series circuit.

[0012] Preferably, the fractional-order capacitor circuit includes a half-bridge inverter and a large capacitor C. D Filter capacitor C F Primary-side compensation capacitor C C and series resonant inductor L F The two ends of the half-bridge inverter are respectively connected to the large capacitor C. D The two ends are connected; the midpoint of the bridge arm of the half-bridge inverter is connected to the filter capacitor C. F One end is connected to the filter capacitor C. F The other end is connected to the primary-side compensation capacitor C C One end is connected to the midpoint of one bridge arm of the high-frequency inverter, and the primary-side compensation capacitor C CThe other end is connected to the series resonant inductor L F One end and transmitting coil L p One end of each is connected to a series resonant inductor L. F The other end is connected to the large capacitor C D The negative terminal is connected, and the transmitting coil L p The other end is through the parasitic resistance R p It is connected to the midpoint of the other arm of the high-frequency inverter.

[0013] Preferably, the series resonant inductor L F and filter capacitor C F It satisfies the following expression:

[0014]

[0015] Where ω represents the frequency of the wireless power transmission device.

[0016] Preferably, the series resonant inductor L F and filter capacitor C F Series resonance occurs, and the large capacitor C D via a half-bridge inverter to compensate the primary-side capacitor C C Injected current i F The equivalent impedance Z of a fractional capacitor at the fundamental frequency FOC Exhibiting negative resistance and capacitance characteristics, the fractional capacitor Z is adjusted by regulating the phase shift angle and duty cycle of the half-bridge inverter. FOC The value of .

[0017] Preferably, the external equivalent impedance Z of the fractional-order capacitor at the fundamental frequency is... FOC It is expressed as follows:

[0018]

[0019] in, This represents the voltage across the primary-side compensation capacitor. This represents the current in a fractional-order capacitor resonant circuit. The primary resonant circuit is represented by R. F X represents the real part of the port impedance of a fractional capacitor; F This represents the imaginary part of the port impedance of a fractional capacitor.

[0020] Preferably, the secondary-side compensation unit includes a secondary-side resonant capacitor C. s Secondary resonant capacitor C s With receiving coil L s Series resonance occurs, and the receiving coil L s One end is connected to the secondary resonant capacitor C s One end is connected, and the secondary resonant capacitor C sThe other end is connected to the midpoint of one bridge arm of the rectifier circuit, and the midpoint of the other bridge arm of the rectifier circuit is connected to the parasitic resistance R. S One end is connected, parasitic resistance R S The other end is connected to the receiving coil L s The other end is connected to form a complete circuit; the load R L It is connected in parallel across the rectifier circuit.

[0021] Preferably, the offset-resistant wireless power transfer device based on a power-free fractional-order capacitor further includes a filter capacitor C. f ; Load R L With filter capacitor C f in parallel.

[0022] Preferably, the receiving coil L s and capacitor C S It satisfies the following expression:

[0023]

[0024] Where ω represents the frequency of the wireless power transmission device.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) This invention is an improvement on the traditional phase-shift control topology. On the load side, the rectifier circuit collects the load voltage and transmits it to the wireless communication chip on the receiver side. The wireless communication transmitter on the receiver side sends the data to the wireless communication receiver on the transmitter side, and then transmits it to the digital processor. After passing through the PI control strategy, the phase shift angle is output. By adjusting the phase shift angle and duty cycle of the fractional capacitor half-bridge inverter, the output voltage can be adjusted until a constant voltage output is achieved, thus realizing a controllable constant voltage output independent of load and distance.

[0027] (2) Compared with the traditional phase-shift control strategy, the present invention is prone to increased switching losses due to hard switching operation. When operating at a fixed switching frequency, the phase relationship between the input voltage and the input current can be adjusted by controlling the phase shift angle, so as to achieve soft switching operation while achieving constant voltage charging process.

[0028] (3) To address the problem of ZVS (Zero Voltage Switch) operation failure under the traditional phase-shift control strategy, this invention introduces a fractional-order capacitor, which, along with the phase shift angle of the fractional-order capacitor... Changes in input current I P The phase also changes accordingly, and the phase shift angle of the fractional capacitor... The controllable range is between 90° and 180°. At this time, the input impedance of the wireless power transmission device is resistive and inductive, thereby maintaining the ZVS operation of the inverter. Attached Figure Description

[0029] Figure 1 This is a topology diagram of an anti-offset wireless power transmission device based on a power-free fractional capacitor according to an embodiment of the present invention.

[0030] Figure 2 This is a topology diagram of a fractional capacitor circuit according to an embodiment of the present invention;

[0031] Figure 3 The following are the control timing diagrams and key waveform diagrams of the fractional capacitor circuit in an embodiment of the present invention;

[0032] Figure 4 The following are voltage and current waveforms of the device according to an embodiment of the present invention under different coil distances and loads; wherein, (a) represents a coil distance of 4.5cm; (b) represents a coil distance of 6.5cm; (c) represents a load of 30Ω; and (d) represents a load of 60Ω.

[0033] Figure 5 This is a schematic diagram of the output voltage and current of the device according to an embodiment of the present invention when the load changes from 30Ω to 60Ω and then back to 30Ω.

[0034] Figure 6 This is a schematic diagram of the output voltage and current of the device according to an embodiment of the present invention, where the coil distance changes from 4.5cm to 6.5cm and then back to 4.5cm. Detailed Implementation

[0035] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0036] like Figure 1 As shown, the present invention discloses an anti-offset wireless power transmission device based on a power-free fractional capacitor, including a transmitter-side circuit, a receiver-side circuit, and a digital processor.

[0037] The transmitting side circuit includes a high-frequency inverter, a fractional capacitor circuit, and a transmitting coil; the input terminal of the high-frequency inverter is connected to the input power supply, and the output terminal of the high-frequency inverter is connected to the fractional capacitor circuit and the transmitting coil, respectively.

[0038] The receiving-side circuit includes a receiving coil, a secondary-side compensation unit, a rectifier circuit, and a load; the receiving coil is wirelessly connected to the transmitting coil, and the receiving coil, the secondary-side compensation unit, the rectifier circuit, and the load are connected in sequence.

[0039] The digital processor receives the output voltage information of the load, compares it with the reference voltage, outputs a phase shift angle, and the PWM generator drives the switching transistors in the fractional capacitor circuit according to the phase shift angle and duty cycle until the output voltage is constant.

[0040] Specifically, one bridge circuit of the high-frequency inverter consists of switches Q1 and Q3 connected in series, and the other bridge circuit consists of switches Q2 and Q4 connected in series; one end of the fractional capacitor is connected to the midpoint of one bridge arm of the high-frequency inverter, representing the parasitic resistance R on the primary side. P One end is connected to the midpoint of the other arm of the high-frequency inverter.

[0041] The switching transistor control method of the high-frequency inverter is as follows: A 50% duty cycle input with the same frequency as the device's operating frequency (e.g., the switching transistor's operating frequency) is applied to the gates of transistors Q1 and Q4; a 50% duty cycle input with the same frequency as the device's operating frequency is applied to the gates of transistors Q2 and Q3, but with a drive signal delayed by half a cycle from transistors Q1 and Q4, to realize the high-frequency inverter circuit. This can be achieved by Fourier decomposition. Where D1 is the duty cycle of the PWM wave input to the high-frequency inverter in the transmitting circuit. In particular, when D1 = 50%,

[0042] The specific topology of the fractional capacitor is as follows: Figure 2 As shown, it includes a half-bridge inverter and a large capacitor C. D Filter capacitor C F Primary-side compensation capacitor C C and series resonant inductor L F Large capacitor C D The two ends are connected to the two ends of the half-bridge inverter circuit, which consists of switching transistors Q5 and Q6 connected in series. The midpoint of the bridge arm of the half-bridge inverter is connected to the filter capacitor C, which resonates in series. F Connected to the primary-side compensation capacitor C. C One end of the capacitor is connected to the negative terminal of the large capacitor and the inductor L. F One end is connected to the primary compensation capacitor C. C At the other end, the filter capacitor C F and inductor L F Satisfies the series resonance relationship: ω represents the frequency of the wireless power transmission device.

[0043] Furthermore, the series resonant inductor L F and filter capacitor C F Series resonance occurs, and the large capacitor C D via a half-bridge inverter to compensate the primary-side capacitor C C Injected current i F The equivalent impedance Z of a fractional capacitor at the fundamental frequencyFOC Exhibiting negative resistance and capacitance characteristics, the fractional capacitor Z is adjusted by regulating the phase shift angle and duty cycle of the half-bridge inverter. FOC The value of Z. The external equivalent impedance Z of a fractional-order capacitor at the fundamental frequency. FOC It is expressed as follows:

[0044]

[0045] in,

[0046] This represents the voltage across the primary-side compensation capacitor. This represents the current in a fractional-order capacitor resonant circuit. The primary resonant circuit is represented by R. F X represents the real part of the port impedance of a fractional capacitor; F This represents the imaginary part of the port impedance of a fractional capacitor.

[0047] Control methods of fractional capacitors, such as Figure 3 As shown, it includes the following aspects:

[0048] (1) To obtain the required turn-on angle of the fractional capacitor, it is necessary to collect the terminal output voltage V. out and the reference value V ref The compared values ​​are then fed into the PI controller to output the phase shift angle. Finally, the PWM generator drives the switching transistors of the half-bridge inverter until the preset reference voltage is reached, thus achieving constant voltage output with anti-offset capability.

[0049] (2) To reduce the number of signals to be acquired, this control method only needs to acquire the output voltage, and only needs to be based on the phase shift angle. This method controls the turn-on angle of the fractional capacitor without requiring control of the inverter and rectifier circuits, making it simple to control.

[0050] (3) To achieve soft-switching operation, the phase lag of the current behind the phase of the voltage needs to be controlled. In this case, it is only necessary to control the switching angle of the fractional capacitor. This ensures that the voltage phase always leads the current phase. The angle is adjusted to achieve soft-switching operation.

[0051] Specifically, the secondary-side compensation unit includes the secondary-side resonant capacitor C. s Secondary resonant capacitor C s With receiving coil L s Series resonance occurs, and the receiving coil L s One end is connected to the secondary resonant capacitor C s One end is connected, and the secondary resonant capacitor C sThe other end is connected to the midpoint of one bridge arm of the rectifier circuit, and the midpoint of the other bridge arm of the rectifier circuit is connected to the parasitic resistance R. S One end is connected, parasitic resistance R S The other end is connected to the receiving coil L s The other end is connected to form a complete circuit; the load R L With filter capacitor C f After being connected in parallel, they are connected in parallel across the two ends of the rectifier circuit.

[0052] Receiving coil L s and capacitor C S It satisfies the following expression:

[0053]

[0054] Where ω represents the frequency of the wireless power transmission device.

[0055] The following will illustrate this with several practical applications. Specifically, the design parameters of each electrical component are as follows.

[0056] 1) Select DC voltage source V in The voltage is 100V, and the large capacitor C D The voltage is 350V;

[0057] 2) Select the rated operating frequency of the switching transistors Q1, Q2, Q3, Q4, Q5 and Q6 as 85kHz;

[0058] 3) Select three capacitors C S C C and C F The capacitance values ​​are 33.5nF, 33.5nF, and 31nF respectively. Three inductors L are selected. P L S and L F The current ratings are 103.52uH, 105.32uH, and 112uH respectively, with a mutual inductance of 20uH. The parasitic resistance R of the two loops is set. S and R P Both are 0.2Ω, so filter capacitor C is selected. f It is 100uF.

[0059] like Figure 4 , Figure 5 and Figure 6 The experimental results lead to the following conclusions:

[0060] 1) By Figure 4 (Including (a) to (d)) it can be seen that, under different distances and loads, the device input current I P Always lagging behind the input voltage U P Therefore, the inverter can always maintain ZVS operation;

[0061] 2) By Figure 5 It can be seen that when the load resistance R L When the voltage is changed from 30Ω to 60Ω and then back to 30Ω, the proposed control strategy can stably control the DC output voltage V. out (i.e., load resistance R) L The output voltage of the device increases slightly, while the input current of the device increases slightly.

[0062] 3) By Figure 6 It can be seen that as the coil distance changes from 4.5cm to 6.5cm and then back to 4.5cm, the output voltage and current remain constant.

[0063] As can be seen from the above, the present invention achieves constant voltage output independent of distance and load, while realizing the switching operation of the inverter, which can effectively reduce losses and improve transmission efficiency.

[0064] This invention achieves constant voltage output under coil offset and load variations by applying fractional-order capacitors to a wireless power transmission device. It requires minimal sampling of electrical quantities and simplifies control. The fractional-order capacitors can be adjusted by the phase shift angle and duty cycle of a half-bridge inverter, enabling adjustable order and capacitance. Connecting a fractional-order capacitor in series on the transmitter side allows for adjusting the phase relationship between the input voltage and current by controlling the phase shift angle, achieving soft-switching operation during charging. Furthermore, the fractional-order capacitors introduce minimal additional losses, and their inherent soft-switching capability further reduces losses. The high-frequency inverter at the transmitter operates in a soft-switching state over a wide range, resulting in low switching losses.

[0065] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A shift-resistant wireless power transfer device based on power-free fractional order capacitance, characterized by, The application relates to a wireless power transmission device. The transmitting side circuit comprises a high-frequency inverter, a fractional-order capacitor circuit and a transmitting coil; the input end of the high-frequency inverter is connected with an input power supply; the output end of the high-frequency inverter is connected with the fractional-order capacitor circuit and the transmitting coil respectively; The receiving side circuit comprises a receiving coil, a secondary side compensation unit, a rectifier circuit and a load; the receiving coil is wirelessly connected with the transmitting coil; the receiving coil, the secondary side compensation unit, the rectifier circuit and the load are sequentially connected; The digital processor receives output voltage information of the load, compares the output voltage information with a reference voltage, outputs a phase shift angle, and drives a switch tube in the fractional-order capacitor circuit according to the phase shift angle and a duty ratio by a PWM generator until the output voltage is constant. Wherein, omega represents the frequency of the wireless power transmission device. The fractional order capacitor circuit comprises a half-bridge inverter, a large capacitor C D , a filter capacitor C F , a primary compensation capacitor C C , and a series resonant inductor L F ; two ends of the half-bridge inverter are connected to two ends of the large capacitor C D ; a bridge arm midpoint of the half-bridge inverter is connected to one end of the filter capacitor C F , the other end of the filter capacitor C F is connected to one end of the primary compensation capacitor C C and one bridge arm midpoint of the high-frequency inverter, the other end of the primary compensation capacitor C C is connected to one end of the series resonant inductor L F and one end of the transmitting coil L p , the other end of the series resonant inductor L F is connected to a negative electrode of the large capacitor C D , and the other end of the transmitting coil L p is connected to the other bridge arm midpoint of the high-frequency inverter through a parasitic resistance R p .

2. The shift based on the power supply-free fractional order capacitor anti-offset wireless power transmission device according to claim 1, characterized in that, One end of a fractional order capacitor is connected to a midpoint of one bridge arm of a high frequency inverter, the other end of the fractional order capacitor is connected to one end of a transmitting coil L p , the other end of the transmitting coil L p is connected to one end of a parasitic resistance R p , the other end of the parasitic resistance R p is connected to the other midpoint of the other bridge arm of the high frequency inverter, forming a series loop.

3. The shift based on the power supply-free fractional order capacitor anti-offset wireless power transmission device according to claim 1, characterized in that, Series resonant inductance L F and filter capacitance C F satisfies the following expression: Wherein, omega represents the frequency of the wireless power transmission device.

4. The shift based on the power supply-free fractional order capacitance anti- offset wireless power transmission device according to claim 1, characterized in that, Series resonant inductance L F and filter capacitance C F Series resonance occurs, large capacitance C D Primary side compensation capacitance C via half-bridge inverter C Injection current i F ; the equivalent impedance Z of fractional order capacitor to the outside at the fundamental frequency FOC Negative resistance and capacitance characteristics, by adjusting the phase shift angle and duty cycle of half-bridge inverter to adjust the value of fractional order capacitor Z FOC .

5. The shift based on the power supply-free fractional order capacitance anti- offset wireless power transmission device according to claim 4, characterized in that, The equivalent impedance of the fractional order capacitor to the outside at the base frequency Z FOC is represented as follows: wherein, represents primary side compensation capacitor voltage; represents fractional order capacitor resonant tank current; represents primary side resonant tank; R F represents fractional order capacitor port impedance real part; X F represents fractional order capacitor port impedance imaginary part.

6. The shift based on the power supply-free fractional order capacitance anti- offset wireless power transmission device according to claim 1, characterized in that, The secondary side compensation unit includes a secondary side resonance capacitor C s ; the secondary side resonance capacitor C s is connected with the receiving coil L s to occur series resonance, one end of the receiving coil L s is connected with one end of the secondary side resonance capacitor C s , and the other end of the secondary side resonance capacitor C s is connected with a bridge arm midpoint of a rectifier circuit, one end of a parasitic resistance R S is connected with the other bridge arm midpoint of the rectifier circuit, and the other end of the parasitic resistance R S is connected with the other end of the receiving coil L s , to form a complete loop; and a load R L is connected in parallel across the rectifier circuit.

7. The shift based on the power supply-free fractional-order capacitance anti-offset wireless power transmission device according to claim 6, characterized in that, Also included is a filter capacitor C f ; load R L in parallel with filter capacitor C f .

8. The anti-shift wireless power transfer device based on power-free fractional order capacitance of claim 6, wherein, Receiving coil L s and a capacitor C S satisfies the following expression: ​

Images