A multi-resonance compensation-based wireless power transmission reconfigurable topology and system

Abstract

The application discloses a wireless power transmission reconfigurable topology based on multi-resonance compensation, which comprises a primary compensation network, a primary transmitting coil, a secondary receiving coil and a secondary compensation network. The reconfigurable topology has two working frequencies f1 and f2, and corresponds to different variation ranges of a coupling coefficient k of the primary transmitting coil and the secondary receiving coil respectively. The application further discloses a wireless power transmission system applying the reconfigurable topology. Under a larger offset range, the reconfigurable topology can change the equivalent compensation network of the primary side by switching the switching frequency, and meanwhile, the secondary compensation network is still in a complete resonance state. Under different switching frequencies, the equivalent compensation network of the primary side is an LCC compensation network and a series compensation network respectively. By designing the power and coupling coefficient characteristics under different compensation networks, relatively stable output under a larger offset range is realized.

Description

Technical Field

[0001] This invention belongs to the field of wireless power transmission technology, specifically relating to a reconfigurable wireless power transmission topology with high offset adaptability based on multi-resonance compensation, applicable to wireless power transmission systems. Background Technology

[0002] Traditional charging methods involve wired contact charging, which suffers from problems such as bulky connectors, cumbersome operation, easy wear and tear, poor reliability, and susceptibility to leakage in rainy or snowy weather. Furthermore, the length and drag of the power cables hinder the flexibility of mobile devices, resulting in high maintenance costs. To improve the safety, reliability, and flexibility of power systems, wireless energy transfer has become a research hotspot. Using wireless power transfer systems for charging and supplying power can overcome the shortcomings of contact charging methods, such as susceptibility to electric shock and environmental influences, achieving green, safe, and efficient energy transfer.

[0003] However, due to the flexibility in the positioning of its primary transmitting coil and secondary receiving coil, offset is unavoidable. This will reduce the system's coupling coefficient and affect the output characteristics. Practical wireless power transfer systems require stable output characteristics within a certain offset range.

[0004] To address the aforementioned issues, existing technologies primarily employ three solutions: First, the entire wireless power transfer system utilizes closed-loop control to compensate for output performance under offset conditions. This can be achieved by adjusting the system's output characteristics through frequency modulation or phase shift control of the inverter circuit. However, this method increases the complexity of system control, and system efficiency decreases as the coupling coefficient decreases. Second, a multi-stage compensation control approach is used, such as adding DC-DC circuits to the front or rear stages of the wireless power transfer system. However, this method increases system cost and complexity. Third, a hybrid compensation topology is used, utilizing compensation structures with different output characteristics connected in series or parallel to achieve stable output characteristics under offset conditions. However, this method only enables offset adaptation in two directions and limits the structure of the primary and secondary coils.

[0005] For example, the patent specification with patent publication number CN115037062A discloses a hybrid compensation structure for resisting offset. When the coupling mechanism is offset, the fundamental and third harmonic power is transmitted through a hybrid compensation circuit. The output power is adjusted by the complementary output characteristics of the two compensation networks, thereby achieving constant power output. However, due to the low utilization rate of the third harmonic component DC voltage, the system can only be used in high coupling situations, which limits its application in low coupling scenarios.

[0006] The paper "ADual-Side Controlled Inductive Power Transfer System Optimized for Large Coupling Factor Variations and Partial Load" published in IEEE Transactions on Power Electronics, Vol. 30, No. 11, pp. 6320-6328, introduces a control strategy to extend the offset and load range of a wireless power transfer system by using phase-shift control and active rectification of the inverter circuit. However, phase-shift control and active rectification cause the switching transistors to operate in a hard-switching state, which reduces the efficiency of the system.

[0007] It can be seen that the current methods all have certain limitations. Therefore, there is an urgent need for a new method to achieve stable output characteristics of wireless power transmission systems within a certain offset range. Summary of the Invention

[0008] In view of the above, the present invention provides a reconfigurable topology for wireless power transmission based on multi-resonance compensation. The wireless power transmission system using this structure can achieve a small change in the output power of the system under a wide range of coupling coefficient variations.

[0009] A reconfigurable topology for wireless power transmission based on multi-resonance compensation includes a primary-side compensation network, a primary-side transmitting coil, a secondary-side receiving coil, and a secondary-side compensation network.

[0010] The primary-side compensation network includes a primary-side series compensation inductor L1, a primary-side series compensation capacitor Cp, a primary-side parallel compensation inductor L2, and a primary-side parallel compensation capacitor C1. The primary-side parallel compensation inductor L2 and the primary-side parallel compensation capacitor C1 form an LC parallel resonant network.

[0011] The primary-side series compensation capacitor Cp and the primary-side transmitting coil Lp form an LC series resonant network 1, and the LC parallel resonant network is connected in parallel with the LC series resonant network 1.

[0012] The two ends of the output side of the inverter circuit are respectively connected to the primary side series compensation inductor L1 and the LC series resonant network 1;

[0013] The secondary-side compensation network includes a secondary-side series compensation capacitor Cs, a secondary-side parallel compensation inductor L3, a secondary-side parallel inductor compensation capacitor C3, a secondary-side parallel compensation capacitor C2, a secondary-side parallel compensation inductor L3, and a secondary-side parallel inductor compensation capacitor C3 and a secondary-side parallel compensation capacitor C2, which together form an LCC parallel resonant network.

[0014] The secondary-side series compensation capacitor Cs and the secondary-side receiving coil Ls form an LC series resonant network 2, and the LCC parallel resonant network is connected in series with the LC series resonant network 2.

[0015] The two ends of the input side of the rectifier circuit are respectively connected to the LC series resonant network 2 and the LCC parallel resonant network.

[0016] The current is shunted at the parallel structure of the LC series resonant network 1 and the LC parallel resonant network through the primary-side series compensation inductor. The shunted current is transmitted to the primary-side transmitting coil through the primary-side series compensation capacitor. By utilizing the electromagnetic field coupling effect, the energy is transferred to the secondary coil. The current is then transmitted to the LCC parallel resonant network, and finally the energy is output through the secondary-side series compensation capacitor Cs.

[0017] Specifically, the reconfigurable topology has two operating frequencies, f1 and f2, which correspond to different ranges of coupling coefficient k between the primary transmitting coil and the secondary receiving coil.

[0018] Specifically, when the inverter circuit switching frequency is at the operating frequency, the reconfigurable topology is in a state of primary-side detuning and secondary-side resonance.

[0019] Preferably, when the reconfigurable topology operates at the operating frequency f1, the reconfigurable topology is equivalent to the LCC-S compensated topology; when the reconfigurable topology operates at the operating frequency f2, the reconfigurable topology is equivalent to the SS compensated topology.

[0020] Preferably, when the reconfigurable topology operates at the operating frequency f1, the output power of the equivalent LCC-S compensated topology first increases and then decreases as the coupling coefficient decreases, and its output characteristic expression is:

[0021]

[0022] Where ω is the inverter switching angular frequency;

[0023] k is the coupling coefficient between the primary transmitting coil and the secondary receiving coil;

[0024] Lp and Ls are the inductances of the primary transmitting coil Lp and the secondary receiving coil Ls, respectively.

[0025] X p1 V is the equivalent reactance of the primary-side LCC compensation network. AB R is the fundamental effective value of the inverter output voltage. eq This is the equivalent AC resistance at the input of the rectifier.

[0026] When the reconfigurable topology operates at the operating frequency f2, the output power of the equivalent SS-compensated topology first increases and then decreases as the coupling coefficient decreases, and its output characteristic expression is as follows:

[0027]

[0028] Among them, X p2 V is the equivalent reactance of the primary-side series compensation network. AB R is the fundamental effective value of the inverter output voltage. eq This is the equivalent AC resistance at the input of the rectifier.

[0029] Preferably, a capacitor is connected in series on the branch where the primary-side parallel compensation inductor is located. This capacitor can be used to reduce the inductance of the primary-side parallel compensation inductor.

[0030] Preferably, the primary transmitting coil and the secondary receiving coil are composed of a shield, a magnetic core, and a loosely coupled transformer wound with Litz wire or conductor. The shield can be made of metal materials such as aluminum plate, copper plate, or steel plate, and the magnetic core can be made of materials such as ferrite, powder core, or amorphous nanocrystal.

[0031] The present invention also provides a wireless power transmission system employing the above-mentioned reconfigurable topology of wireless power transmission based on multi-resonance compensation, including a DC input power supply, an inverter circuit, the aforementioned reconfigurable topology of wireless power transmission based on multi-resonance compensation, a rectifier circuit, and a load.

[0032] Preferably, the inverter circuit can be a half-bridge inverter circuit, a full-bridge inverter circuit, a multi-level inverter circuit, or a push-pull inverter circuit.

[0033] Therefore, compared with the prior art, the advantages of the present invention are:

[0034] This invention allows the reconfigurable topology to alter the primary-side equivalent compensation network by switching the switching frequency over a large offset range, while the secondary-side compensation network remains in full resonance. At different switching frequencies, the primary-side equivalent compensation network consists of an LCC compensation network and a series compensation network, respectively. By designing the power and coupling coefficient characteristics of different compensation networks, stable output over a large offset range is achieved. Attached Figure Description

[0035] Figure 1 This is a structural diagram of the reconfigurable topology based on multi-resonance compensation of the present invention.

[0036] Figure 2 This is a structural diagram of the topology of the present invention at a switching frequency f1.

[0037] Figure 3This is a Thevenin equivalent structural diagram of the primary-side compensation network of the topology of the present invention at a switching frequency f1.

[0038] Figure 4 This is a structural diagram of the topology of the present invention at a switching frequency f2.

[0039] Figure 5 This is the output characteristic curve of the present invention, which shows the output power and coupling coefficient.

[0040] Figure 6 This is the experimental waveform of the present invention at the switching frequency f1 at the switching frequency switching point.

[0041] Figure 7 This is the experimental waveform of the present invention at the switching frequency f2 at the switching frequency switching point. Detailed Implementation

[0042] To describe the present invention in more detail, the technical solution of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0043] To verify the feasibility and effectiveness of the wireless power transmission system based on reconfigurable topology with multi-resonance compensation proposed in this invention, an experimental prototype with a rated output power of 450W was built in this example. The reconfigurable topology of wireless power transmission based on multi-resonance compensation of this invention was adopted, and the invention was explained in detail based on experimental results and mathematical analysis.

[0044] like Figure 1 As shown, the wireless power transmission system based on reconfigurable topology with multi-resonance compensation in this embodiment includes a DC power supply, an inverter circuit, a primary-side compensation network, a primary-side transmitting coil, a secondary-side receiving coil, a secondary-side compensation network, a rectifier circuit, and a load.

[0045] The primary-side compensation network includes a primary-side series compensation inductor L1, a primary-side series compensation capacitor Cp, a primary-side parallel compensation inductor L2, and a primary-side parallel compensation capacitor C1.

[0046] The primary-side parallel compensation inductor L2 and the primary-side parallel compensation capacitor C1 form an LC parallel resonant network;

[0047] The primary-side series compensation capacitor Cp and the primary-side transmitting coil Lp form an LC series resonant network 1;

[0048] The LC parallel resonant network is connected in parallel with the LC series resonant network 1;

[0049] The two ends of the output side of the inverter circuit are respectively connected to the primary side series compensation inductor L1 and the LC series resonant network 1;

[0050] The secondary-side compensation network includes a secondary-side series compensation capacitor Cs, a secondary-side parallel compensation inductor L3, a secondary-side parallel inductor compensation capacitor C3, and a secondary-side parallel compensation capacitor C2.

[0051] The secondary-side parallel compensation inductor L3, the secondary-side parallel inductor compensation capacitor C3, and the secondary-side parallel compensation capacitor C2 form an LCC parallel resonant network;

[0052] The secondary-side series compensation capacitor Cs and the secondary-side receiving coil Ls form an LC series resonant network 2;

[0053] The LCC parallel resonant network is connected in series with the LC series resonant network 2;

[0054] The two ends of the input side of the rectifier circuit are respectively connected to the LC series resonant network 2 and the LCC parallel resonant network.

[0055] Based on the given application objectives of the system, including the system's input DC voltage Vin = 120V, rated output power P = 450W, the coupling coefficient k between the primary transmitting coil and the secondary receiving coil ranging from 0.16 to 0.35, primary-side compensation network detuning, and secondary-side compensation network resonance, the output characteristics of the wireless power transfer system can be expressed as:

[0056]

[0057] Where Xp is the equivalent reactance of the primary-side compensation network, VAB is the fundamental RMS value of the inverter output voltage, and Req is the equivalent AC resistance at the rectifier input, expressed as:

[0058]

[0059] The system coupling coefficient range is divided into a high coupling range (0.247-0.35) and a low coupling range (0.16-0.247), and two different switching frequencies f1 and f2 are selected according to the different coupling coefficient ranges.

[0060] In the high coupling range, the topology operates at the switching frequency f1, at which point the secondary-side compensation network is in a fully resonant state. The parallel branch composed of L1 and C1 in the primary-side compensation network can be equivalent to Ceq, and can be expressed as:

[0061]

[0062] When the system operates at switching frequency f1, the equivalent topology is an LCC-S compensated topology, such as... Figure 2 As shown.

[0063] In the low coupling range, the topology operates at the switching frequency f2. At this time, the secondary-side compensation network is in a fully resonant state, and the parallel branch composed of L1 and C1 in the primary-side compensation network is also in a resonant state. The resonance condition is as follows:

[0064] ω2 2 L2C1=1 (6)

[0065] When the system operates at switching frequency f2, the equivalent topology is an SS-compensated topology, such as... Figure 4 As shown.

[0066] The primary-side compensation network is designed by making the output power Pmin corresponding to the minimum coupling coefficient equal to the output power corresponding to the maximum coupling coefficient Pmax. The specific process is as follows:

[0067] To maximize the offset range kmin-kmax (kmax = αkmin), by equalizing the output power corresponding to the maximum and minimum coupling coefficients, the equivalent reactance of the primary-side compensation network can be obtained as follows:

[0068]

[0069] α is the ratio of the maximum coupling coefficient to the minimum coupling coefficient.

[0070] Based on the complete resonance condition at two different switching frequencies f1 and f2, a secondary-side compensation network is designed, and the specific process is as follows:

[0071] In the high coupling range, the proposed topology operates at the switching frequency f1, and the resonance condition of the secondary compensation network is as follows:

[0072]

[0073] In the low coupling range, the proposed topology operates at the switching frequency f2, and the resonance condition of the secondary-side compensation network is as follows:

[0074]

[0075] Depending on the different coupling ranges, the output power variation coefficient Fp within that coupling range is set by making the maximum output power equal to the rated output power. The specific process is as follows:

[0076] Define the coefficient of change Fp of the output power as the coupling coefficient changes:

[0077]

[0078] In practical design, to prevent system overvoltage or overcurrent, the maximum output power is usually designed to be the rated power. Therefore, the maximum output power (rated power) at the switching frequency f1 can be obtained as follows:

[0079]

[0080] Where Vs is the primary-side equivalent Thevenin circuit voltage of the LCC-S topology corresponding to the switching frequency f1, such as Figure 3 As shown, Xp1 is the equivalent Thevenin circuit reactance of the primary side of the LCC-S topology corresponding to the switching frequency f1, and its value is:

[0081]

[0082] Substituting (11) into (10), we can obtain the power fluctuation coefficient Fp1 at the switching frequency f1 as follows:

[0083]

[0084] At a switching frequency f2, the maximum output power (rated power) is:

[0085]

[0086] Substituting (14) into (10), we can obtain the power fluctuation coefficient Fp2 at the switching frequency f2 as follows:

[0087]

[0088] The frequency switching point of the system is obtained by equivaling the maximum and minimum output power at two different switching frequencies and equipping the minimum coupling coefficient kmin1 in the high coupling range with the maximum coupling coefficient kma2 in the low coupling range. The design constraints are as follows:

[0089]

[0090] The experimental element parameters are shown in Table 1.

[0091] Table 1 System Experimental Component Parameters

[0092]

[0093] When the coupling coefficient of the experimental prototype changes, the output power measurement results are as follows: Figure 5 As shown.

[0094] like Figure 5As shown, the output power varies from 407W to 455W in the low coupling range and from 414W to 452W in the high coupling range. The output power variation of the reconfigurable topology is consistent across the two switching frequencies, i.e., the power variation coefficient is less than 10% across the entire coupling coefficient range (0.16–0.35).

[0095] When the experimental prototype operates at the switching frequency f1, at the maximum offset of the high coupling range (i.e., coupling coefficient k = 0.247), and the operating frequency is 76kHz, the specific waveform is as follows: Figure 6 As shown.

[0096] When the experimental prototype operates at the switching frequency f1, and the minimum offset of the low coupling range occurs (i.e., coupling coefficient k = 0.247, operating frequency 80kHz), the specific waveform is as follows: Figure 7 As shown.

[0097] Depend on Figure 6 , 7 It can be seen that the inverter can achieve zero-voltage turn-on when the experimental prototype is at the maximum or minimum coupling coefficient.

[0098] Therefore, the reconfigurable topology based on multi-resonance compensation proposed in this invention can achieve stable system output power over a large offset range. Within this range, the reconfigurable topology can change the equivalent compensation network on the primary side by switching the switching frequency, while ensuring the secondary side compensation network remains in full resonance. At different switching frequencies, the equivalent compensation networks on the primary side are an LCC compensation network and a series compensation network, respectively. By designing the power versus coupling coefficient characteristic curves for different compensation networks, stable output over a large offset range is achieved. In a 450W experimental prototype, by switching different switching frequencies, the output power variation within the coupling coefficient range of 0.16-0.35 is less than 10%.

[0099] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. It will be apparent to those skilled in the art that various modifications can be made to the above embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A reconfigurable wireless power transfer topology based on multi-resonance compensation, characterized in that: This includes the primary-side compensation network, the primary-side transmitting coil, the secondary-side receiving coil, and the secondary-side compensation network. The primary-side compensation network includes a primary-side series compensation inductor L1, a primary-side series compensation capacitor Cp, a primary-side parallel compensation inductor L2, and a primary-side parallel compensation capacitor C1. The primary-side parallel compensation inductor L2 and the primary-side parallel compensation capacitor C1 form an LC parallel resonant network. The primary-side series compensation capacitor Cp and the primary-side transmitting coil Lp form an LC series resonant network 1, and the LC parallel resonant network is connected in parallel with the LC series resonant network 1. The two ends of the inverter circuit output side are connected to the primary side series compensation inductor L1 and the LC series resonant network 1, respectively. The secondary-side compensation network includes a secondary-side series compensation capacitor Cs, a secondary-side parallel compensation inductor L3, a secondary-side parallel inductor compensation capacitor C3, and a secondary-side parallel compensation capacitor C2. The secondary-side parallel compensation inductor L3, the secondary-side parallel inductor compensation capacitor C3, and the secondary-side parallel compensation capacitor C2 form an LCC parallel resonant network. The secondary-side series compensation capacitor Cs and the secondary-side receiving coil Ls form an LC series resonant network 2; The LCC parallel resonant network is connected in series with the LC series resonant network 2; The two ends of the input side of the rectifier circuit are respectively connected to the LC series resonant network 2 and the LCC parallel resonant network; The reconfigurable topology has two operating frequencies, f1 and f2, which correspond to different ranges of coupling coefficient k between the primary transmitting coil and the secondary receiving coil. When the switching frequency of the inverter circuit is at one of the two operating frequencies f1 and f2, the reconfigurable topology is in a state of primary-side detuning and secondary-side resonance. When the reconfigurable topology operates at the operating frequency f1, the reconfigurable topology is equivalent to the LCC-S compensated topology; When the reconfigurable topology operates at the operating frequency f2, the reconfigurable topology is equivalent to the SS-compensated topology.

2. The reconfigurable wireless power transfer topology based on multi-resonance compensation according to claim 1, characterized in that: When the reconfigurable topology operates at the operating frequency f1, the output power of the equivalent LCC-S compensated topology first increases and then decreases as the coupling coefficient decreases. Its output characteristic expression is as follows: in, This refers to the inverter's switching angular frequency. k This is the coupling coefficient between the primary transmitting coil and the secondary receiving coil; Lp, Ls These are the inductances of the primary transmitting coil Lp and the secondary receiving coil Ls, respectively. X p1 The equivalent reactance of the primary-side LCC compensation network. V AB This represents the fundamental RMS value of the inverter output voltage. R eq Here is the equivalent AC resistance at the rectifier input; when the reconfigurable topology operates at the operating frequency f2, the output power of the equivalent SS-compensated topology first increases and then decreases as the coupling coefficient decreases, and its output characteristic expression is: in, X p2 This is the equivalent reactance of the primary-side series compensation network. V AB This represents the fundamental RMS value of the inverter output voltage. R eq This is the equivalent AC resistance at the input of the rectifier.

3. The reconfigurable wireless power transfer topology based on multi-resonance compensation according to claim 1, characterized in that: A capacitor is connected in series on the branch where the primary-side parallel compensation inductor is located. This capacitor is used to reduce the inductance of the primary-side parallel compensation inductor.

4. The reconfigurable wireless power transfer topology based on multi-resonance compensation according to claim 1, characterized in that: The primary-side transmitting coil and the secondary-side receiving coil are composed of a shielded, magnetically conductive core and a loosely coupled transformer wound with Litz wire or conductor.

5. The reconfigurable wireless power transfer topology based on multi-resonance compensation according to claim 4, characterized in that: The shielding uses aluminum plates, copper plates, or steel plates, and the magnetic core uses ferrite, powder core, or amorphous nanocrystalline materials.

6. A wireless power transmission system, characterized in that: It includes a DC input power supply, an inverter circuit, a reconfigurable wireless power transfer topology based on multi-resonance compensation as described in any one of claims 1-5, a rectifier circuit, and a load.

7. The wireless power transmission system according to claim 6, characterized in that: The inverter circuit adopts a half-bridge inverter circuit, a full-bridge inverter circuit, a multi-level inverter circuit, or a push-pull inverter circuit.

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