Wireless power transmission compensation topological structure with constant voltage output and control method

Abstract

The invention discloses a wireless electric energy transmission compensation topological structure with constant voltage output and a control method, and relates to the technical field of wireless electric energy transmission. The wireless electric energy transmission compensation topological structure with the constant voltage output mainly comprises a direct current power supply, an inverter circuit, a primary side transmitting coil, a secondary side receiving coil, a secondary side series compensation capacitor, a secondary side parallel compensation capacitor, a rectification filter circuit and a load, wherein the inverter circuit is used for converting output direct current of the direct current power supply into high-frequency alternating current. By implementing the wireless power transmission compensation topological structure with constant voltage output and the control method provided by the invention, a primary side structure can be simplified, multi-path integration of a transmitting end is facilitated, the system cost is reduced, load-independent constant voltage output is realized, the inverter loss is reduced, and the transmission efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of wireless power transmission, and more particularly to a wireless power transmission compensation topology structure with constant voltage output and a control method. Background Art

[0002] Wireless power transmission technology enables contactless energy transfer. Compared to traditional plug-in, wired charging technologies, wireless power transmission offers advantages such as safety, reliability, low maintenance, weather resistance, and ease of operation. Inductive wireless power transmission technology, due to the distance between the primary and secondary sides, uses a loosely coupled transformer. This loosely coupled transformer exhibits significant leakage inductance. Therefore, to offset the effects of the loosely coupled transformer's high leakage inductance, a compensation topology is often incorporated into the system to compensate for reactive power, thereby reducing inverter current stress and improving system efficiency.

[0003] In practical applications, the system needs to output a constant voltage. Adding a control strategy will increase system complexity and increase system cost. Therefore, a more convenient approach is to design a compensation topology that has a certain constant voltage output characteristic. Among existing compensation topology designs, compensation topologies such as S / S (string / string), LCC / S, S / LCC, and S / SP have constant voltage output capabilities. The S / S compensation topology has a constant voltage output characteristic under leakage inductance compensation, but the reactive power on the AC side of the inverter is extremely large, and the system efficiency is low. The LCC / S and S / LCC compensation topologies have step-down constant voltage output capabilities and step-up constant voltage output capabilities, respectively. However, the presence of inductor components in the compensation circuit increases the system cost and volume, and a total of four compensation components are required, resulting in a large number of components overall.

[0004] Among existing compensation structures, the S / S compensation topology offers simplicity and low cost, but sacrifices system performance. The LCC / S and S / LCC compensation topologies are simpler in design and achieve unity power factor for the inverter, but at the expense of system cost. In summary, in view of the actual application of wireless power transmission in today's field, the existing compensation circuit design still has room for further improvement and optimization. In the design of compensation topology with constant voltage output characteristics, how to propose a simpler compensation topology structure and lower system cost without sacrificing system performance is an urgent problem to be solved.

[0005] The above content is only used to assist in understanding the technical solution of the present invention and does not constitute an admission that the above content is prior art. Summary of the Invention

[0006] The purpose of the present invention is to provide a wireless power transmission compensation topology structure and control method with constant voltage output, which can simplify the primary side structure, facilitate multi-channel integration at the transmitter end, reduce system costs, achieve load-independent constant voltage output, reduce inverter losses, and improve transmission efficiency.

[0007] The present invention provides a wireless power transmission compensation topology with constant voltage output, including a DC power supply, an inverter circuit, a primary transmitting coil, a secondary receiving coil, a secondary series compensation capacitor, a secondary parallel compensation capacitor, a rectifier and filter circuit, and a load. The inverter circuit is used to convert the DC power output of the DC power supply into high-frequency AC power to drive the primary transmitting coil.

[0008] Furthermore, the DC side of the above-mentioned inverter circuit is electrically connected to the DC power supply, and the AC side of the inverter circuit is electrically connected to the primary transmitting coil; energy is transferred between the primary transmitting coil and the secondary receiving coil through electromagnetic coupling; one end of the secondary receiving coil is connected to one end of the secondary series compensation capacitor, the other end of the secondary receiving coil is connected to one end of the secondary parallel compensation capacitor, and the other end of the secondary series compensation capacitor is connected to the other end of the secondary parallel compensation capacitor; the two ends of the secondary parallel compensation capacitor are respectively electrically connected to the two ends of the AC side of the rectifier and filter circuit; and the two ends of the DC side of the rectifier and filter circuit are respectively electrically connected to the two ends of the load.

[0009] Furthermore, the inverter circuit adopts a half-bridge inverter structure, a full-bridge inverter structure or a push-pull inverter structure.

[0010] Furthermore, the primary transmitting coil includes a magnetic core and an energy transmission coil, the energy transmission coil is wound by a wire, and the magnetic core is a magnetic conductive material.

[0011] Furthermore, the secondary receiving coil includes a magnetic core and an energy transmission coil, the energy transmission coil is wound by a wire, and the magnetic core is a magnetic conductive material.

[0012] Furthermore, the parameters of the secondary receiving coil, the secondary series compensation capacitor, the secondary parallel compensation capacitor, and the primary transmitting coil satisfy the following resonance conditions: , , in, represents the imaginary unit, represents the angular frequency, represents the inductance of the secondary receiving coil, represents the secondary side series compensation capacitor, Represents the secondary side parallel compensation capacitor, Indicates the coupling coefficient between the primary transmitting coil and the secondary receiving coil.

[0013] Furthermore, the primary transmitting coil is also connected in series with a series DC blocking capacitor.

[0014] The present invention also provides a control method applied to the above-mentioned wireless power transmission compensation topology structure with constant voltage output, including: adjusting the secondary side series compensation capacitor, the secondary side parallel compensation capacitor, the inductance of the primary side transmitting coil and the secondary side receiving coil to obtain an inductive or capacitive input impedance angle.

[0015] The implementation of the wireless power transmission compensation topology structure and control method with constant voltage output provided by the present invention has the following beneficial effects: The present invention provides a wireless power transmission compensation topology with constant voltage output, which includes a DC power supply, an inverter circuit, a primary-side compensation circuit, a transmitting and receiving coil, a rectifier and filter circuit, and a load. The primary side adopts an uncompensated mode and only includes a transmitting coil. The secondary-side receiving coil is connected in series with a compensation capacitor, and then the entire structure is connected in parallel with another compensation capacitor. This parallel compensation capacitor is also connected in parallel with the AC side of the rectifier. Through parameter design, this compensation topology can achieve load-independent constant voltage output, achieve zero phase angle on the input side, and basically eliminate reactive power on the input side, thereby reducing inverter losses and improving efficiency. Compared with the existing compensation topology that realizes constant voltage input and zero input phase angle, the compensation topology proposed in the present invention has a primary side that only includes a transmitting coil and no compensation components. The resonant cavity is more streamlined and fewer passive components are used to achieve the same function. It has the characteristics of a compact primary side, which is conducive to multi-channel integration at the transmitting end and lowers the system cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention will be further described below with reference to the accompanying drawings and embodiments, in which: Figure 1 This is a flow chart of a wireless power transmission compensation topology with constant voltage output provided by the present invention; Figure 2 This is a schematic diagram of an equivalent circuit model of a wireless power transmission structure provided by the present invention; Figure 3 This is a schematic diagram of an equivalent circuit model of the wireless power transmission structure provided by the present invention, which converts the self-inductance of the primary coil to the secondary coil; Figure 4 This is the waveform diagram of the inverter circuit at 1 / 8 rated power; Figure 5 This is the waveform diagram of the rectifier circuit at 1 / 8 rated power; Figure 6 The waveform diagram of the inverter circuit at 5 / 8 rated power; Figure 7 This is the waveform diagram of the rectifier circuit at 5 / 8 rated power; Figure 8 It is the waveform diagram of the inverter circuit at rated power; Figure 9 This is the waveform diagram of the rectifier circuit at rated power. DETAILED DESCRIPTION

[0017] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described in detail with reference to the accompanying drawings.

[0018] Figure 1 A schematic diagram of a wireless power transmission compensation topology with constant voltage output according to this embodiment is shown.

[0019] In this embodiment, a wireless power transmission compensation topology with constant voltage output includes: a DC power supply, an inverter circuit, a primary transmitting coil, a secondary receiving coil, a secondary series compensation capacitor, a secondary parallel compensation capacitor, a rectifier filter circuit, and a load; In an exemplary embodiment, the inverter circuit is used to convert the output DC power of the DC power supply into high-frequency AC power to drive the primary transmitting coil; In an exemplary embodiment, the DC side of the inverter circuit is electrically connected to the DC power supply, and the AC side of the inverter circuit is electrically connected to the primary transmitting coil; energy is transferred between the primary transmitting coil and the secondary receiving coil via electromagnetic coupling; one end of the secondary receiving coil is connected to one end of the secondary series compensation capacitor, the other end of the secondary receiving coil is connected to one end of the secondary shunt compensation capacitor, and the other end of the secondary series compensation capacitor is connected to the other end of the secondary shunt compensation capacitor; the two ends of the secondary shunt compensation capacitor are respectively electrically connected to the two ends of the AC side of the rectifier and filter circuit; and the two ends of the DC side of the rectifier and filter circuit are respectively electrically connected to the two ends of the load. In an exemplary embodiment, the inverter circuit adopts a half-bridge inverter structure, a full-bridge inverter structure or a push-pull inverter structure.

[0020] In an exemplary embodiment, the primary transmitting coil includes a magnetic core and an energy transmission coil, the energy transmission coil is wound by a wire, and the magnetic core is a magnetic conductive material; In an exemplary embodiment, the secondary receiving coil includes a magnetic core and an energy transmission coil, the energy transmission coil is wound by a wire, and the magnetic core is a magnetic conductive material; In an exemplary embodiment, the parameters of the secondary receiving coil, the secondary series compensation capacitor, the secondary parallel compensation capacitor, and the primary transmitting coil satisfy the following resonance conditions: , , in, represents the imaginary unit, represents the angular frequency, represents the inductance of the secondary receiving coil, represents the secondary side series compensation capacitor, Represents the secondary side parallel compensation capacitor, Indicates the coupling coefficient between the primary transmitting coil and the secondary receiving coil; In an exemplary embodiment, the primary transmitting coil is further connected in series with a series DC blocking capacitor; This embodiment provides a control method for the above-mentioned wireless power transmission compensation topology with constant voltage output, including: adjusting the secondary side series compensation capacitor, the secondary side parallel compensation capacitor, the inductance of the primary side transmitting coil and the secondary side receiving coil to obtain an inductive or capacitive input impedance angle.

[0021] In this embodiment, the wireless power transmission compensation topology with constant voltage output includes: a DC power supply, an inverter circuit, a primary transmitting coil L p , secondary side receiving coil L s , secondary side series compensation capacitor C s , secondary side parallel compensation capacitor C 2. Rectification filter circuit and load.

[0022] The connection of the proposed compensation structure is as follows: the DC side of the inverter circuit is connected to the DC power supply to convert the output DC power of the DC power supply into high-frequency AC power, and the two ends of the AC side of the inverter circuit are directly connected to the primary transmitting coil. L p The two ends are connected; the primary transmitting coil L p and the secondary receiving coil L s Energy is transferred between them through electromagnetic coupling; the secondary receiving coil L s One end is connected to the secondary side series compensation capacitor C s One end of the secondary receiving coil L s The other end is connected to the secondary parallel compensation capacitor C One end of 2, the secondary side is connected in series with the compensation capacitor C s The other end is connected in parallel with the secondary side compensation capacitor C 2; the other end of the secondary side is connected in parallel with the compensation capacitor C 2. The two ends are directly connected to the two ends of the AC side of the rectifier circuit. The two ends of the DC side of the rectifier circuit are connected to the two ends of the load through the output filter.

[0023] In an exemplary embodiment, the inverter circuit adopts an inverter structure such as a half-bridge inverter structure, a full-bridge inverter structure, or a push-pull inverter structure.

[0024] In an exemplary embodiment, the primary transmitting coil part or the secondary receiving coil part is composed of an energy transmission coil wound with a magnetic core and a wire, and the magnetic core is made of magnetic conductive material.

[0025] In an exemplary embodiment, the secondary receiving coil L s , secondary side series compensation capacitor C s , secondary side parallel compensation capacitor C 2. And the coupling coefficient of the coupling coil k The parameters are designed to meet the following resonance conditions: Condition 1: ; Condition 2: ; In an exemplary embodiment, the primary transmitting coil L p , secondary side receiving coil L s , secondary side series compensation capacitor C s , secondary side parallel compensation capacitor C 2 can be fine-tuned under the constraints of conditions 1 and 2 above to produce a slightly inductive or capacitive input impedance angle.

[0026] In an exemplary embodiment, the primary transmitting coil L p A DC blocking capacitor can be connected in series on the branch where the inductor is located to eliminate the DC current component on the parallel inductor branch.

[0027] In some embodiments, the aforementioned wireless power transfer compensation topology with constant voltage output may also be implemented in the following manner.

[0028] The following combination Figure 1 、 Figure 2 and Figure 3 The design principle of the wireless power transmission compensation topology structure with constant voltage output proposed in this embodiment is described. Figure 1 The compensation topology structure includes a DC power supply 1, an inverter circuit 2, a compensation circuit 3, a rectifier and filter circuit 4 and a load 5.

[0029] Figure 2 This is a simplified compensation circuit using fundamental wave analysis and loosely coupled transformer T model. It includes the primary transmitting coil. L p , secondary side receiving coilL s , secondary side series compensation capacitor C s , secondary side parallel compensation capacitor C 2. Mutual inductance between the transmitting and receiving coils M The coupling coefficient is expressed as k Indicates. Some circuit parameters are defined as follows: V in : DC power input voltage; V o : DC output voltage on the load side; I o : DC output current on the load side; R o : Equivalent load resistance on the DC side after filtering of the rectifier circuit; R eq : Equivalent load resistance on the AC side of the rectifier circuit; U p : The effective value of the fundamental voltage on the AC side of the inverter circuit; U s : The effective value of the fundamental voltage on the AC side of the rectifier circuit; L p 、 L s 、 C s 、 C 2: The inductance and capacitance at the corresponding positions in the original secondary side compensation circuit; M 、 k : The mutual inductance and coupling coefficient of the loosely coupled transformer are related by M = k ; Due to the parallel capacitor on the secondary side of the proposed compensation topology, in order to avoid the existence of a purely capacitive loop, an inductor filter needs to be added after the rectifier circuit. According to the fundamental wave analysis method, the relationship between the AC side voltage and current effective value and the DC voltage and current of the inverter circuit and the rectifier circuit is: (1) The equivalent load resistance on the AC and DC sides of the rectifier circuit is (2) Figure 2 A T-type gyrator is naturally formed in the loosely coupled transformer T model, so the self-inductance of the transmitting coil L p Before it can be converted to a T-type gyrator, the equivalent circuit is: Figure 3 This circuit can help understand and analyze the resonance principle of the invented structure. C eq is the equivalent series capacitance, and its conversion condition is: (3) According to the equivalent circuit Figure 3 To achieve a constant voltage output, an even number of gyrator networks should be present in the system, thus performing two source conversions on the input voltage source: from a voltage source to a current source and then back to a voltage source. Therefore, the preceding π-type network needs to form a gyrator, and the resonant condition of the circuit is: (4) Combining equations (3) and (4), the resonance condition is simplified to: (5) At this time, after the transformation of the first-stage π-type gyrator and the first-stage T-type gyrator, the voltage gain E for: (6) Equivalent input impedance of inverter circuit Z in for: (7) According to equations (6) and (7), the compensation structure of the present invention has a load-independent constant voltage output capability, and the equivalent impedance on the input side is purely resistive, with a power factor close to 1. Compared with existing compensation topologies that achieve load-independent constant voltage output and unity power factor on the input side, the compensation structure of this embodiment requires only two compensation capacitors and has the fewest resonant components. Compared with the LCC / S or S / LCC compensation topologies, it saves one resonant capacitor and one resonant inductor, and compared with the S / SP compensation topology, it saves one resonant capacitor.

[0030] The above-mentioned wireless power transmission compensation topology with constant voltage output and its control method are verified through a design example.

[0031] This embodiment designed an experimental prototype with a rated power of 1.5kW. The input DC voltage was 300V, and the output DC voltage was constant at 240V. When the input voltage remained unchanged, the voltage gain remained at 0.8. At an operating frequency of 85kHz, the parameters were designed according to the resonance conditions 1 and 2 of claim 4. The designed compensation structure parameters are as follows:

[0032] The effects of this embodiment are described below using actual simulation test results and waveforms. Figure 4 、 Figure 5 and Figure 6 This is a simulation experiment waveform of the primary-side compact wireless power transmission compensation topology structure with constant voltage output of the present invention.

[0033] Figures 4 to 9The waveforms are the AC side voltage of the inverter circuit, the AC side current of the inverter circuit, the AC side voltage of the rectifier circuit, the AC side current of the rectifier circuit and the DC output current of the system under different powers. Figure 4 、 Figure 6 、 Figure 8 is the waveform diagram of the inverter circuit, Figure 5 、 Figure 7 、 Figure 9 is the waveform diagram of the rectifier circuit. u p and i p is the voltage and current on the AC side of the inverter circuit, u s and i s is the voltage and current on the AC side of the rectifier circuit, i o is the system output current; Figure 4 and Figure 5 The waveform is at 1 / 8 rated power, the load resistance is 300Ω, the output voltage is 240V, and the current is 0.8A; Figure 4 and Figure 5 The waveforms are the AC side voltage and current of the inverter circuit, the AC side voltage and current of the rectifier circuit, and the DC output current of the system at 1 / 8 rated power. Figure 4 is the waveform diagram of the inverter circuit, Figure 5 It is the waveform diagram of the rectifier circuit; Figure 6 and Figure 7 This is the waveform at 5 / 8 rated power, load resistance is 60Ω, output voltage is 240V, current is 4A; Figure 6 and Figure 7 The waveforms are the AC side voltage and current of the inverter circuit, the AC side voltage and current of the rectifier circuit, and the DC output current of the system at 5 / 8 rated power. Figure 6 is the waveform diagram of the inverter circuit, Figure 7 It is the waveform diagram of the rectifier circuit; Figure 8 and Figure 9 This is the waveform under rated power, load resistance is 37.5Ω, output voltage is 240V, and current is 6.4A; Figure 8 and Figure 9 Waveforms of the inverter circuit AC side voltage, inverter circuit AC side current, rectifier circuit AC side voltage, rectifier circuit AC side current and system DC output current at rated power; Figure 8 is the waveform diagram of the inverter circuit, Figure 9 It is the waveform diagram of the rectifier circuit; As can be seen, the system can achieve a set 240V constant voltage output over a wide load range of 37.5Ω to 300Ω, demonstrating the constant voltage output capability of the compensation topology of the present invention. Over this wide load range, the inverter voltage and current remain nearly in phase, and the input impedance angle is zero, demonstrating that the compensation topology of the present invention can achieve a near-unity power factor. These experimental results demonstrate that the output characteristics of the present invention are consistent with the design.

[0034] The embodiments of the present invention are described above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned specific implementation methods. The above-mentioned specific implementation methods are merely illustrative and not restrictive. Under the guidance of the present invention, ordinary technicians in this field can also make many forms without departing from the scope of protection of the present invention and the claims, all of which are protected by the present invention.

Claims

1. A wireless power transmission compensation topology with constant voltage output, characterized in that: It includes a DC power supply, an inverter circuit, a primary transmitting coil, a secondary receiving coil, a secondary series compensation capacitor, a secondary parallel compensation capacitor, a rectifier filter circuit and a load. The inverter circuit is used to convert the output DC power of the DC power supply into high-frequency AC power to drive the primary transmitting coil.

2. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The DC side of the inverter circuit is electrically connected to the DC power supply, and the AC side of the inverter circuit is electrically connected to the primary transmitting coil; energy is transferred between the primary transmitting coil and the secondary receiving coil via electromagnetic coupling; one end of the secondary receiving coil is connected to one end of the secondary series compensation capacitor, the other end of the secondary receiving coil is connected to one end of the secondary shunt compensation capacitor, and the other end of the secondary series compensation capacitor is connected to the other end of the secondary shunt compensation capacitor; and both ends of the secondary shunt compensation capacitor are electrically connected to both ends of the AC side of the rectifier and filter circuit, respectively. The two ends of the DC side of the rectifier and filter circuit are electrically connected to the two ends of the load respectively.

3. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The inverter circuit adopts a half-bridge inverter structure, a full-bridge inverter structure or a push-pull inverter structure.

4. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The primary transmitting coil includes a magnetic core and an energy transmission coil. The energy transmission coil is wound by a wire, and the magnetic core is made of a magnetic conductive material.

5. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The secondary receiving coil includes a magnetic core and an energy transmission coil. The energy transmission coil is wound by a wire, and the magnetic core is made of a magnetic conductive material.

6. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The parameters of the secondary receiving coil, the secondary series compensation capacitor, the secondary parallel compensation capacitor and the primary transmitting coil satisfy the following resonance conditions: ， ， in, represents the imaginary unit, represents the angular frequency, represents the inductance of the secondary receiving coil, represents the secondary side series compensation capacitor, Represents the secondary side parallel compensation capacitor, Indicates the coupling coefficient between the primary transmitting coil and the secondary receiving coil.

7. The wireless power transmission compensation topology with constant voltage output according to claim 1, characterized in that: The primary transmitting coil is further connected in series with a series DC blocking capacitor.

8. A control method for a wireless power transmission compensation topology structure with constant voltage output according to any one of claim 7, characterized in that: include: Adjust the secondary side series compensation capacitor, the secondary side parallel compensation capacitor, the inductance of the primary side transmitting coil and the secondary side receiving coil to obtain the inductive or capacitive input impedance angle.

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