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

Abstract

The invention discloses an anti-offset wireless electric energy transmission device based on a power supply-free fractional order capacitor. The anti-offset wireless electric energy transmission device 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 respectively connected with the fractional order capacitor circuit and the transmitting coil; the receiving side circuit comprises a receiving coil, a secondary side compensation unit, a rectifying circuit and a load; the receiving coil is wirelessly connected with the transmitting coil, and the receiving coil, the secondary side compensation unit, the rectifying circuit and the load are connected in sequence; and the digital processor receives the output voltage information of the load, compares the output voltage information with the reference voltage, outputs a phase shift angle, and drives a switching tube in the fractional order capacitor circuit according to the phase shift angle and the duty ratio until the output voltage is constant. The fractional order capacitor is applied to the wireless electric energy transmission device, and constant voltage output under coil offset and load change is achieved.

Description

Technical Field

[0001] The present invention relates to the field of wireless power transmission, and in particular to an anti-offset wireless power transmission device based on power-free fractional-order capacitors. Background Art

[0002] Wireless Power Transmission (WPT), also known as contactless power transmission technology, refers to the conversion of electrical energy into electromagnetic waves by the transmitter, and then the energy is collected and converted back into electrical energy by the receiver, thereby realizing wireless power transmission. Compared with traditional wired power supply methods, wireless power transmission technology has significant advantages in certain specific occasions (such as walls, underwater or biological environments) because the construction complexity of these occasions is high and the flexibility of equipment charging is required. In these cases, wireless power transmission technology can not only effectively solve the complex electrical wiring problems in traditional wired power supply methods, but also reduce mechanical switching operations, improve power supply reliability, reduce the consumption of physical consumables, and shorten the construction period.

[0003] With the rapid development of new energy technologies, the load's requirements for the accuracy of power supply are increasing, and more efficient, convenient and stable power supply methods have gradually become a research hotspot. The standardization of charging conditions has promoted the development of wireless power transmission technology in terms of power supply stability, especially in the realization of constant voltage, constant current and constant power modes. However, due to the influence of distance changes and system parasitic parameters, it is often difficult for WPT systems to maintain a controllable constant output in topology design. With the continuous advancement of technology, more and more researchers are committed to using different technical means to achieve constant voltage output of wireless power transmission. Traditional methods, such as switched inductors or switched capacitors, usually require additional closed-loop control circuits and sampling circuits, and their control process is relatively complex, the adjustment range is limited, and it is difficult to achieve a wide range of output adjustment. Therefore, introducing components with a wider range of impedance adjustment capabilities in WPT systems has become a key challenge to solve the system output adjustment range and improve the system output robustness. Solving this problem is crucial to promoting the development of controllable rectifier wireless power transmission technology.

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

[0005] The main purpose of the present invention is to overcome the above-mentioned defects in the prior art and propose an anti-offset wireless power transmission device based on power-free fractional-order capacitors, which provides capacitive impedance through adjustable fractional-order capacitors and keeps the output voltage constant by changing the phase shift angle after the offset. At the same time, the phase relationship between the input voltage and the input current can be adjusted by controlling the phase shift angle to achieve soft switching operation during the charging process.

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

[0007] An anti-offset wireless power transmission device based on power-free fractional-order capacitors comprises: a transmitting side circuit, a receiving side circuit and a digital processor;

[0008] 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 to an input power supply, and the output end of the high-frequency inverter is connected to the fractional-order 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, and outputs a phase shift angle. The PWM generator drives the switch tube in the fractional-order capacitor circuit according to the phase shift angle and the 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 the fractional-order capacitor, and the other end of the fractional-order capacitor is connected to the transmitting coil L p One end of the transmitting coil L p The other end of the parasitic resistance R p One end is connected to the parasitic resistance R p The other end is connected to the midpoint of the other bridge arm of the high-frequency inverter to form a series loop.

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

[0013] Preferably, the series resonant inductor L F And filter capacitor C F Satisfies the following expression:

[0014]

[0015] Here, 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, the large capacitor C D The half-bridge inverter is used to compensate the primary side capacitor C C Injection current i F ; The external equivalent impedance Z of the fractional-order capacitor at the fundamental frequency FOC It exhibits negative resistance and capacitance characteristics. By adjusting the phase shift angle and duty cycle of the half-bridge inverter, the fractional-order capacitor Z is adjusted. 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, Indicates the primary compensation capacitor voltage; Represents the fractional-order capacitor resonant circuit current; Table primary resonant circuit; R F represents the real part of the fractional capacitor port impedance; X F Represents the imaginary part of the fractional capacitor port impedance.

[0020] Preferably, the secondary side compensation unit includes a secondary side resonant capacitor C s ; Secondary side resonant capacitor C s With receiving coil L s Series resonance occurs, the receiving coil L s One end of the secondary resonant capacitor C s One end is connected to 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 to the parasitic resistance R S The other end of the receiving coil L s The other end of the load R L Connected in parallel at both ends of the rectifier circuit.

[0021] Preferably, the anti-offset wireless power transmission device based on fractional-order capacitor without power supply 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 Satisfies the following expression:

[0023]

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

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present 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 transmitting device on the receiver side sends the data to the wireless communication receiving device on the transmitter side, and then transmits it to the digital processor. After the PI control strategy, the output phase shift angle By adjusting the phase shift angle and duty cycle of the half-bridge inverter with fractional capacitors, the output voltage can be adjusted until a constant voltage output is achieved, thus achieving a controllable constant voltage output that is independent of load and distance.

[0027] (2) Compared with the traditional phase shift control strategy, the present invention is prone to increase 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, thereby achieving soft switching operation while realizing a constant voltage charging process;

[0028] (3) To solve the problem of failure of ZVS (zero voltage switching) operation under the traditional phase shift control strategy, the present invention introduces fractional-order capacitors. Changes in input current I P The phase of the fractional capacitor also changes. The controllable range is between 90°-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. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A topological diagram of an anti-offset wireless power transmission device based on power-free fractional-order capacitors according to an embodiment of the present invention;

[0030] Figure 2 A topological diagram of a fractional-order capacitor circuit according to an embodiment of the present invention;

[0031] Figure 3 A control timing diagram and a key waveform diagram of a fractional-order capacitor circuit according to an embodiment of the present invention;

[0032] Figure 4 The voltage and current waveforms of the device of the embodiment of the present invention under different coil distances and loads; wherein (a) indicates that the coil distance is 4.5 cm; (b) indicates that the coil distance is 6.5 cm; (c) indicates that the load is 30Ω; (d) indicates that the load is 60Ω;

[0033] Figure 5 It is a schematic diagram of 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 to 30Ω;

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

[0035] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall within the scope limited by the appended claims of the application equally.

[0036] like Figure 1 As shown, the present invention discloses an anti-offset wireless power transmission device based on power-free fractional-order capacitors, including a transmitting side circuit, a receiving side circuit and a digital processor;

[0037] 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 to an input power supply, and the output end of the high-frequency inverter is connected to the fractional-order 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, and outputs a phase shift angle. The PWM generator drives the switch tube in the fractional-order capacitor circuit according to the phase shift angle and the duty cycle until the output voltage is constant.

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

[0041] The switch control method of the high-frequency inverter is: input a 50% duty cycle and a frequency of the device operating frequency (such as the switch operating frequency) to the gate of the switch tubes Q1 and Q4; input a 50% duty cycle and a frequency of the device operating frequency to the gate of the switch tubes Q2 and Q3, but the start-up is delayed by half a cycle of the switch tubes Q1 and Q4. The drive signal is used to realize a high-frequency inverter circuit, and the Fourier decomposition can be obtained. 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, a large capacitor C D 、Filter capacitor C F , primary compensation capacitor C C and the series resonant inductor L F . Large capacitor C D The two ends are connected to the two ends of the half-bridge inverter circuit. The half-bridge inverter circuit is composed of switch tubes Q5 and Q6 connected in series. The midpoint of the bridge arm of the half-bridge inverter is connected to the filter capacitor C that generates series resonance. F and connected to the primary compensation capacitor C C The point where the negative electrode of the large capacitor is connected to the inductor L F One end is connected to the primary compensation capacitor C C The other end of the filter capacitor C F and inductor L F Satisfying 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, the large capacitor C D The half-bridge inverter is used to compensate the primary side capacitor C C Injection current i F ; The external equivalent impedance Z of the fractional-order capacitor at the fundamental frequencyFOC It exhibits negative resistance and capacitance characteristics. By adjusting the phase shift angle and duty cycle of the half-bridge inverter, the fractional-order capacitor Z is adjusted. FOC The external equivalent impedance Z of the fractional capacitor at the fundamental frequency is FOC It is expressed as follows:

[0044]

[0045] in,

[0046] Indicates the primary compensation capacitor voltage; Represents the fractional-order capacitor resonant circuit current; Table primary resonant circuit; R F represents the real part of the fractional capacitor port impedance; X F Represents the imaginary part of the fractional capacitor port impedance.

[0047] The control method of fractional capacitors is as follows: Figure 3 As shown, it includes the following aspects:

[0048] (1) To obtain the required opening angle of the fractional capacitor, it is necessary to collect the terminal output voltage V out And with the reference value V ref After comparison, it is sent to the PI controller to output the phase shift angle Finally, the PWM generator drives the half-bridge inverter switch tube until the preset reference voltage is reached, thus achieving anti-offset constant voltage output.

[0049] (2) In order to reduce the number of collected signals, this control method only needs to collect the output voltage and only needs to calculate the phase shift angle. To control the opening angle of the fractional-order capacitor, there is no need to control the inverter and rectifier circuit. This method is simple to control.

[0050] (3) To achieve soft switching operation, the current needs to be controlled to lag behind the voltage phase. In this case, we only need to control the switching angle of the fractional capacitor to This means that the voltage phase always leads the current phase Angle, thereby achieving soft switching operation.

[0051] Specifically, the secondary side compensation unit includes a secondary side resonant capacitor C s ; Secondary side resonant capacitor C s With receiving coil L s Series resonance occurs, the receiving coil L s One end of the secondary resonant capacitor C s One end is connected to 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 to the parasitic resistance R S The other end of the receiving coil L s The other end of the load R L With filter capacitor C f After parallel connection, it is connected in parallel at both ends of the rectifier circuit.

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

[0053]

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

[0055] Several practical applications are used as examples to illustrate the above. Specifically, the parameters of each electrical component are designed as follows.

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

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

[0058] 3) Select three capacitors C S , C C and C F Select three inductors L, which are 33.5nF, 33.5nF and 31nF respectively. P , L S and L F They 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 The filter capacitor C is selected as 0.2Ω. f is 100uF.

[0059] like Figure 4 , Figure 5 and Figure 6 From the experimental results, we can draw the following conclusions:

[0060] 1) By Figure 4 (including (a) to (d)) It can be seen that at different distances and loads, the device input current I P Always lags behind the input voltage U P , so 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 DC output voltage V changes from 30Ω to 60Ω and then to 30Ω, the proposed control strategy can stably control the DC output voltage V out (i.e. load resistance R L ) while the device input current increases slightly;

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

[0063] It can be seen from the above that the present invention realizes constant voltage output that is independent of distance and load, and realizes the switching operation of the inverter, which can effectively reduce losses and improve transmission efficiency.

[0064] The present invention realizes constant voltage output under coil offset and load variation by applying fractional-order capacitors to wireless power transmission devices, requiring less electrical quantity to be sampled and simple to control; the phase shift angle and duty cycle of the fractional-order capacitors can be adjusted by a half-bridge inverter to realize adjustability of the order and capacitance; the phase relationship between the input voltage and the input current can be adjusted by controlling the phase shift angle by connecting the fractional-order capacitors in series on the transmitting side to realize soft switching operation during the charging process; in addition, the additional loss caused by the fractional-order capacitors is small, and the soft switching of the fractional-order capacitors themselves further reduces the loss; the high-frequency inverter at the transmitting end is in a soft switching state within a wide range, and the switching loss is small.

[0065] The above is only a preferred specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. An anti-offset wireless power transmission device based on power-free fractional-order capacitors, characterized in that: include: Transmitting side circuit, receiving side circuit and 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 to an input power supply, and the output end of the high-frequency inverter is connected to the fractional-order capacitor circuit and the transmitting coil respectively; 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; The digital processor receives the output voltage information of the load, compares it with the reference voltage, and outputs a phase shift angle. The PWM generator drives the switch tube in the fractional-order capacitor circuit according to the phase shift angle and the duty cycle until the output voltage is constant.

2. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 1, characterized in that: The midpoint of one arm of the high-frequency inverter is connected to one end of the fractional-order capacitor, and the other end of the fractional-order capacitor is connected to the transmitting coil L p One end of the transmitting coil L p The other end of the parasitic resistance R p One end is connected to the parasitic resistance R p The other end is connected to the midpoint of the other bridge arm of the high-frequency inverter to form a series loop.

3. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 1, characterized in that: The fractional-order capacitor circuit includes a half-bridge inverter, a large capacitor C D 、Filter capacitor C F , primary compensation capacitor C C and the series resonant inductor L F The two ends of the half-bridge inverter are 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 of the filter capacitor C F The other end of the primary compensation capacitor C C One end of the primary compensation capacitor C is connected to the midpoint of one bridge arm of the high-frequency inverter. C The other end of the series resonant inductor L F One end and the transmitting coil L p The end of each is connected to the series resonant inductor L F The other end is connected to the large capacitor C D The negative pole of the transmitting coil L p The other end is connected through the parasitic resistor R p Connected to the midpoint of the other bridge arm of the high-frequency inverter.

4. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 3, characterized in that: Series resonant inductor L F And filter capacitor C F Satisfies the following expression: Here, ω represents the frequency of the wireless power transmission device.

5. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 3, characterized in that: Series resonant inductor L F And filter capacitor C F Series resonance occurs, the large capacitor C D The half-bridge inverter is used to compensate the primary side capacitor C C Injection current i F ; The external equivalent impedance Z of the fractional-order capacitor at the fundamental frequency FOC It exhibits negative resistance and capacitance characteristics. By adjusting the phase shift angle and duty cycle of the half-bridge inverter, the fractional-order capacitor Z is adjusted. FOC The value of .

6. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 5, characterized in that: The external equivalent impedance Z of the fractional capacitor at the fundamental frequency FOC It is expressed as follows: in, Indicates the primary compensation capacitor voltage; Represents the fractional-order capacitor resonant circuit current; Table primary resonant circuit; R F represents the real part of the fractional capacitor port impedance; X F Represents the imaginary part of the fractional capacitor port impedance.

7. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 1, characterized in that: The secondary side compensation unit includes a secondary side resonant capacitor C s ; Secondary side resonant capacitor C s With receiving coil L s Series resonance occurs, the receiving coil L s One end of the secondary resonant capacitor C s One end is connected to the secondary resonant capacitor C s The 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 to the parasitic resistance R S The other end of the receiving coil L s The other end of the load R L Connected in parallel at both ends of the rectifier circuit.

8. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 7, characterized in that: Also includes filter capacitor C f ; Load R L With filter capacitor C f in parallel.

9. The anti-offset wireless power transmission device based on fractional-order capacitor without power supply according to claim 7, characterized in that: Receiving coil L s and capacitor C S Satisfies the following expression: Here, ω represents the frequency of the wireless power transmission device.

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