Variable frequency reconfigurable wireless power transmission system and parameter design method

Abstract

This invention relates to a frequency-reconfigurable wireless power transfer system and its parameter design method. The invention addresses the problem that existing wireless power transfer technologies struggle to maintain near-constant power transfer when faced with wide fluctuations in coupling coefficients, and also suffer from high system control complexity. The system comprises a full-bridge inverter circuit, a primary-side compensation network, coupling coils, a secondary-side compensation network, and a rectifier-filter circuit; the input of the full-bridge inverter circuit is connected to a DC voltage source U. D The output of the full-bridge inverter circuit is connected to the input of the primary-side compensation network. The output of the primary-side compensation network is connected to the primary-side input of the coupling coil. The secondary-side output of the coupling coil is connected to the input of the secondary-side compensation network. The output of the secondary-side compensation network is connected to the input of the rectifier-filter circuit. The output of the rectifier-filter circuit is connected to the battery load R. o This invention belongs to the field of wireless power transmission technology.

Description

Technical Field

[0001] This invention relates to a wireless power transmission system and parameter design method, belonging to the field of wireless power transmission technology. Background Technology

[0002] Inductive power transfer (IPT) technology uses alternating electromagnetic fields as a medium to achieve contactless energy transfer from power source to load, offering advantages such as power supply safety, flexibility, and reliability. It has already found practical applications in various fields, including electric vehicles, drones, and underwater exploration. However, in most applications, misalignment between the transmitting and receiving coils is unavoidable, leading to significant fluctuations in mutual inductance and coupling parameters between the coils. This, in turn, greatly impacts the stability of power transmission in the IPT system.

[0003] To address the aforementioned problems, research teams both domestically and internationally have primarily focused on closed-loop control technology and compensation topology design. Among these, anti-offset technology using control offers the most precise maintenance of system output power; however, it requires the introduction of an additional DC-DC converter or phase-shift control of the inverter module. Furthermore, when pulse frequency modulation is involved, system frequency splitting easily occurs, significantly reducing system stability. Additionally, when the coupling coefficient fluctuates significantly, system control becomes relatively complex due to limitations in modulation margin. To reduce control pressure and system complexity, some researchers have shifted their focus to compensation topology design. For example, Southwest Jiaotong University proposed a hybrid compensation topology based on four coils, achieving IPT system offsets of ±225mm in the X direction, -30mm to +50mm in the Y direction, and -20mm to +70mm in the Z direction, with output current fluctuations within 5%. However, when the receiving coil deviates from the allowable operating range or is completely removed, the current flowing through the transmitting coil surges exponentially, directly damaging the system. Moreover, the use of four coupling coils results in a relatively complex magnetic structure and increases system cost, size, and weight. Therefore, how to maintain near-constant power transmission while reducing system control complexity in the face of wide coupling coefficient fluctuations is one of the key issues in IPT technology research. Summary of the Invention

[0004] This invention addresses the problem that existing wireless power transmission technologies struggle to maintain near-constant power transmission when faced with wide fluctuations in coupling coefficients, while also exhibiting high system control complexity. Therefore, this invention proposes a frequency-reconfigurable wireless power transmission system and its parameter design method.

[0005] The technical solution adopted by the present invention to solve the above problems is as follows: The frequency-reconfigurable wireless power transmission system of the present invention includes a full-bridge inverter circuit, a primary-side compensation network, a coupling coil, a secondary-side compensation network, and a rectifier filter circuit;

[0006] The input terminal of the full-bridge inverter circuit is connected to a DC voltage source U. D The output of the full-bridge inverter circuit is connected to the input of the primary-side compensation network. The output of the primary-side compensation network is connected to the primary-side input of the coupling coil. The secondary-side output of the coupling coil is connected to the input of the secondary-side compensation network. The output of the secondary-side compensation network is connected to the input of the rectifier-filter circuit. The output of the rectifier-filter circuit is connected to the battery load R. o ;

[0007] The primary-side compensation network consists of a primary-side series compensation capacitor C. p1 Primary circuit compensation capacitor C p2 Primary branch compensation capacitor C x Primary branch compensation inductor L x constitute;

[0008] The coupling coil consists of the first transmitting coil L p1 Second transmitting coil L p2 Receiver coil L s constitute;

[0009] The secondary-side compensation network consists of a secondary-side series compensation capacitor C. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 constitute.

[0010] Furthermore, the primary-side series compensation capacitor C p1 One end is connected to one output terminal of the full-bridge inverter circuit, and a compensation capacitor C is connected in series on the primary side. p1 The other end is connected to the first transmitting coil L p1 One end;

[0011] Primary circuit compensation capacitor C p2 One end is connected to the other output terminal of the full-bridge inverter circuit and the primary branch compensation capacitor C. x One end is connected to the primary circuit compensation capacitor C. p2 The other end is connected to the second transmitting coil L p2 One end;

[0012] Primary branch compensation capacitor C x One end is connected to the other output terminal of the full-bridge inverter circuit and the primary-side circuit compensation capacitor C. p2 One end is connected to the primary branch compensation capacitor C. x The other end is connected to the primary branch compensation inductor L x One end;

[0013] Primary branch compensation inductor L x One end is connected to the primary branch compensation capacitor C xAt the other end, the original side branch compensation inductor L x The other end is connected to the first transmitting coil L p1 The other end and the second transmitting coil L p2 The other end is connected.

[0014] Furthermore, the secondary-side series compensation capacitor C s One end is connected to the receiving coil L s One end, with a secondary side connected in series with a compensation capacitor C s The other end is connected to one output terminal of the rectifier filter circuit;

[0015] Secondary loop compensation capacitor C s1 One end is connected to the receiving coil L s The other end and the secondary loop compensation inductor L s1 One end is connected to the secondary loop compensation capacitor C. s1 The other end connects to the other output of the rectifier filter circuit and the secondary loop compensation inductor L. s1 The other end is connected;

[0016] Secondary loop compensation inductor L s1 One end is connected to the receiving coil L s The other end and the secondary loop compensation capacitor C s1 One end is connected to the secondary loop compensation inductor L. s1 The other end connects to the other output terminal of the rectifier filter circuit and the secondary loop compensation capacitor C. s1 The other end is connected.

[0017] Furthermore, it also includes two operating angular frequencies ω H ω L , and respectively correspond to strongly coupled mode and weakly coupled mode;

[0018] The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is ω H At that time, i.e., strongly coupled mode:

[0019] The primary-side branch compensation capacitor C in the primary-side compensation network x And the original side branch compensation inductor L x The primary-side series compensation capacitor C forms a series resonant network. p1 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the first transmitting coil L in the coupling coil p1 The secondary-side series compensation capacitor C forms a series detuned network. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1and the receiving coil L in the coupling coil s This forms a series resonant network;

[0020] Specifically:

[0021]

[0022] In the formula, α is the primary-side detuning rate under strongly coupled mode;

[0023] The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is ω L At that time, i.e., strongly coupled mode:

[0024] The primary-side branch compensation capacitor C in the primary-side compensation network x And the original side branch compensation inductor L x The series connection is equivalent to a compensation capacitor C. eq The primary-side series compensation capacitor C in the primary-side compensation network p1 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the first transmitting coil L in the coupling coil p1 The primary-side loop compensation capacitor C forms a series resonant network. p2 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the second transmitting coil L in the coupling coil p2 A parallel resonant network is formed, wherein the secondary side of the secondary compensation network is connected in series with a compensation capacitor C. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 and the receiving coil L in the coupling coil s This forms a series resonant network;

[0025] Specifically:

[0026] System output power P in strongly coupled mode oH The expression is as follows:

[0027]

[0028] The flow through the first transmitting coil L in the strongly coupled mode p1 Current I p1H The expression is as follows:

[0029]

[0030] System input impedance Z in strongly coupled modes inH and its phase angle θ inHThe expression is as follows:

[0031]

[0032] The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is ω L At this time, i.e., weakly coupled mode:

[0033] System output power P in weakly coupled mode oL The expression is as follows:

[0034]

[0035] The flow through the first transmitting coil L in the weakly coupled mode p1 Current I p1L and flowing through the second transmitting coil L p2 Current I p2L The expression is as follows:

[0036]

[0037] The system input impedance Z in weakly coupled modes inL and its phase angle θ inL The expression is as follows:

[0038]

[0039] In the formula, C eq The capacitance value of the equivalent compensation capacitor of the primary branch, L p1 L is the self-inductance of the first transmitting coil. p2 The self-inductance value of the second transmitting coil, L s M is the self-inductance value of the receiving coil; p1s M is the main coupling mutual inductance value between the first transmitting coil and the receiving coil. p2s k is the main coupling mutual inductance value between the second transmitting coil and the receiving coil. p1s Let k be the coupling coefficient between the first transmitting coil and the receiving coil. p2s ω is the coupling coefficient between the second transmitting coil and the receiving coil. H The system operating angular frequency ω under strongly coupled modes L U is the system operating angular frequency in the weakly coupled mode; D The voltage value of the DC voltage source, U AB The output voltage value of the full-bridge inverter circuit, R o The resistance value of the battery load, R eq α represents the equivalent AC resistance before the rectifier and filter circuit; j is the imaginary unit; α is the primary-side detuning rate in the strongly coupled mode.

[0040] The parameter design method described in this invention specifically includes:

[0041] Step 1: Based on actual operating conditions, set the system technical specifications, including: DC input voltage U. D Preset output power P oset Battery load R o System output power fluctuation ratio δ, system operating angular frequency ω under strongly coupled modes H ;

[0042] Step 2: Based on the design requirements of the coupling coil in the frequency-reconfigurable wireless power transmission system, obtain the first transmitting coil L using finite element simulation software. p1 Second transmitting coil L p2 Receiver coil L s The self-induction value;

[0043] Step 3: Based on the set system output power fluctuation ratio δ, calculate the coupling change factor β under the strongly coupled mode. H Coupling variation factor β under weakly coupled modes L ;

[0044] Step 4: Based on the obtained coupling change factor β H β L Calculate the equivalent compensation capacitance C of the original branch respectively. eq The system operating angular frequency ω under weakly coupled modes L ;

[0045] Step 5: Determine the minimum operating coupling coefficient k in the system power-coupling curve. min Peak coupling coefficient k in weakly coupled modes exL Critical coupling coefficient k during frequency switching cri Peak coupling coefficient k in strongly coupled modes exH Maximum working coupling coefficient k max And the actual coupling change factor β o ;

[0046] Step 6: Based on the operating angular frequency ω of the frequency-reconfigurable wireless power transmission system... H and ω L The resonance conditions or relationships between the various compensation elements are determined, and the parameters of each compensation element are tuned accordingly.

[0047] Furthermore, step 1 specifically includes:

[0048] The definition of the system output power fluctuation ratio δ is as follows:

[0049]

[0050] Among them, Pomax and P omin These are the maximum and minimum power values ​​that the frequency-reconfigurable wireless power transmission system is allowed to transmit, respectively, and they are defined to have the following relationship:

[0051]

[0052] In the formula, P oset The preset output power is set to a specific value; to prevent battery overvoltage or overcurrent, the preset output power P is set to a specific value. oset The design is based on the maximum power P that the system is allowed to transmit. omax Place.

[0053] Furthermore, step 3 specifically includes

[0054] Coupling variation factor β under strongly coupled modes H The definition is as follows:

[0055]

[0056] Where, k max For the maximum working coupling coefficient, k cri Let be the critical coupling coefficient during frequency switching, and define the coupling change factor β under strongly coupled modes. H It can be calculated using the following formula:

[0057]

[0058] In the formula, δ H This refers to the system output power fluctuation ratio under strongly coupled modes;

[0059] Coupling variation factor β in weakly coupled modes L The definition is as follows:

[0060]

[0061] Where, k cri The critical coupling coefficient during frequency switching, k min The minimum working coupling coefficient is defined, and the coupling change factor β under weakly coupled modes is specified. L It can be calculated using the following formula:

[0062]

[0063] In the formula, δ L This represents the system output power fluctuation ratio under weakly coupled modes.

[0064] Furthermore, step 4 specifically includes:

[0065] The equivalent compensation capacitor C of the primary branch eq The calculation formula is as follows:

[0066]

[0067] In the formula, β H The coupling change factor under strongly coupled modes, L p1 The self-inductance of the first transmitting coil, ω H This refers to the system's operating angular frequency under strongly coupled modes;

[0068] The system operating angular frequency ω in weakly coupled modes L The calculation formula is as follows:

[0069]

[0070] In the formula, β L The coupling change factor under weakly coupled modes, ω H This represents the system's operating angular frequency under strongly coupled modes.

[0071] Furthermore, step 5 specifically includes:

[0072] The critical coupling coefficient k during frequency switching in the system power-coupling curve cri The calculation formula is as follows:

[0073]

[0074] In the formula, C eq The capacitance value of the equivalent compensation capacitor of the primary branch, R o The resistance value of the battery load, ω H The system operating angular frequency ω under strongly coupled modes L For the system operating angular frequency in weakly coupled modes, L p1 L is the self-inductance of the first transmitting coil. s Let be the self-inductance value of the receiving coil, and define its relationship with other coupling coefficients in the curve as follows:

[0075]

[0076] In the formula, β H The coupling change factor and β under strongly coupled modes L The coupling change factor under weakly coupled modes, k min For the minimum working coupling coefficient, k exL The peak coupling coefficient, k, in the weakly coupled mode. exH The peak coupling coefficient, k, under strongly coupled modes max The maximum working coupling coefficient;

[0077] Actual coupling change factor β o The definition is as follows:

[0078]

[0079] Where, k max For the maximum working coupling coefficient, k min The minimum working coupling coefficient is defined, and the actual coupling variation factor β is specified. o It can be calculated using the following formula:

[0080] β o =β H β L

[0081] In the formula, β H The coupling change factor and β under strongly coupled modes L This represents the coupling change factor under weakly coupled modes.

[0082] Furthermore, step 6 specifically includes:

[0083] The primary-side series compensation capacitor C in the primary-side compensation network p1 The calculation formula is as follows:

[0084]

[0085] The primary-side loop compensation capacitor C in the primary-side compensation network p2 The calculation formula is as follows:

[0086]

[0087] The primary branch compensation capacitor C in the primary-side compensation network x The calculation formula is as follows:

[0088]

[0089] The primary branch compensation inductor L in the primary-side compensation network x The calculation formula is as follows:

[0090]

[0091] The secondary-side series compensation capacitor C in the secondary-side compensation network s The range of values ​​for is as follows:

[0092]

[0093] The secondary loop compensation capacitor C in the secondary compensation network s1 The calculation formula is as follows:

[0094]

[0095] Secondary loop compensation inductor L in the secondary compensation networks1 The calculation formula is as follows:

[0096]

[0097] In the formula, C eq The capacitance value of the equivalent compensation capacitor of the primary branch, L p1 L is the self-inductance of the first transmitting coil. p2 The self-inductance value of the second transmitting coil, L s ω is the self-inductance of the receiving coil. H The system operating angular frequency ω under strongly coupled modes L This represents the system's operating angular frequency in the weakly coupled mode.

[0098] The beneficial effects of this invention are:

[0099] 1. By switching the operating frequency of the system, the present invention can reconfigure the equivalent topology of the primary-side compensation network, while the secondary-side compensation network is always equivalent to a series resonant network, thereby realizing the switching between strongly coupled modes and weakly coupled modes;

[0100] 2. Without adding any control unit or AC switch, the present invention can maintain a near constant power transmission over a wide range of coupling coefficient fluctuations, while avoiding the risk of overcurrent in the transmitting coil, and the inverter switch always remains on with zero voltage.

[0101] 3. The parameter design method for a frequency-reconfigurable wireless power transmission system described in this invention does not require any additional iterative or optimization algorithms. It can directly perform assignment calculations, realize the rapid determination of all system parameters, and simplify the system parameter design steps. Attached Figure Description

[0102] Figure 1 This is a schematic diagram of the overall architecture of the frequency-reconfigurable wireless power transmission system in an embodiment of the present invention;

[0103] Figure 2 In this embodiment of the invention, the system's operating angular frequency is ω. H The equivalent circuit diagram of the system at that time;

[0104] Figure 3 In this embodiment of the invention, the system's operating angular frequency is ω. L The equivalent circuit diagram of the system at that time;

[0105] Figure 4 This is a flowchart illustrating the steps of the parameter design method for a frequency-reconfigurable wireless power transmission system in an embodiment of the present invention.

[0106] Figure 5 This is a schematic diagram of the system power-coupling curve design in an embodiment of the present invention;

[0107] Figure 6 This is a theoretical calculation diagram of the system power-coupling curve in an embodiment of the present invention. Detailed Implementation

[0108] Specific implementation method one: as follows Figure 1 As shown, a frequency-reconfigurable wireless power transmission system includes a full-bridge inverter circuit, a primary-side compensation network, a coupling coil, a secondary-side compensation network, and a rectifier filter circuit.

[0109] The input terminal of the full-bridge inverter circuit is connected to a DC voltage source U. D The output of the full-bridge inverter circuit is connected to the input of the primary-side compensation network. The output of the primary-side compensation network is connected to the primary-side input of the coupling coil. The secondary-side output of the coupling coil is connected to the input of the secondary-side compensation network. The output of the secondary-side compensation network is connected to the input of the rectifier-filter circuit. The output of the rectifier-filter circuit is connected to the battery load R. o ;

[0110] The primary-side compensation network consists of a primary-side series compensation capacitor C. p1 Primary circuit compensation capacitor C p2 Primary branch compensation capacitor C x Primary branch compensation inductor L x constitute;

[0111] The coupling coil consists of the first transmitting coil L p1 Second transmitting coil L p2 Receiver coil L s constitute;

[0112] The secondary-side compensation network consists of a secondary-side series compensation capacitor C. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 constitute.

[0113] In the original edge compensation network:

[0114] The primary-side series compensation capacitor C p1 One end is connected to one output terminal of the full-bridge inverter circuit, and the primary side is connected in series with a compensation capacitor C. p1 The other end is connected to the first transmitting coil L p1 One end;

[0115] The primary circuit compensation capacitor C p2 One end is connected to the other output terminal of the full-bridge inverter circuit and the primary-side branch compensation capacitor C. x At one end, the original side loop compensation capacitor C p2 The other end is connected to the second transmitting coil Lp2 One end;

[0116] The primary side branch compensation capacitor C x One end is connected to the other output terminal of the full-bridge inverter circuit and the primary-side circuit compensation capacitor C. p2 At one end, the primary side branch compensation capacitor C x The other end is connected to the primary branch compensation inductor L x One end;

[0117] The primary branch compensation inductor L x One end is connected to the primary branch compensation capacitor C x At the other end, the primary side branch compensation inductor L x The other end is connected to the first transmitting coil L p1 The other end, the second transmitting coil L p2 The other end.

[0118] In the secondary edge compensation network:

[0119] The secondary-side series compensation capacitor C s One end is connected to the receiving coil L s At one end, the secondary side is connected in series with a compensation capacitor C. s The other end is connected to one output terminal of the rectifier filter circuit;

[0120] The secondary loop compensation capacitor C s1 One end is connected to the receiving coil L s At the other end, the secondary loop compensation inductor L s1 At one end, the secondary loop compensation capacitor C s1 The other end is connected to the other output terminal of the rectifier filter circuit and the secondary loop compensation inductor L. s1 The other end;

[0121] The secondary loop compensation inductor L s1 One end is connected to the receiving coil L s The other end, the secondary loop compensation capacitor C s1 At one end, the secondary loop compensation inductor L s1 The other end is connected to the other output terminal of the rectifier filter circuit and the secondary loop compensation capacitor C. s1 The other end.

[0122] In the coupling coil:

[0123] First transmitting coil L p1 With the second transmitting coil L p2 It is in a naturally decoupled state, that is, the first transmitting coil L p1With the second transmitting coil L p2 Cross-coupling mutual inductance M between p1p2 Under normal operating conditions, it equals zero;

[0124] First transmitting coil L p1 With the receiving coil L s The main coupling mutual inductance between M p1s The value is not zero under normal operating conditions; the second transmitting coil L p2 With the receiving coil L s The main coupling mutual inductance between M p2s It is not zero under normal operating conditions.

[0125] First transmitting coil L p1 and the second transmitting coil L p2 The self-inductances are equal, and the main coupled mutual inductance M p1s and the main coupled mutual inductance M p2s They have equal amplitudes but opposite polarities.

[0126] Combination Figure 2 and Figure 3 As shown, the frequency-reconfigurable wireless power transfer system has two operating angular frequencies ω. H ω L , and respectively correspond to strongly coupled mode and weakly coupled mode.

[0127] like Figure 2 As shown, the operating angular frequency of the frequency-reconfigurable wireless power transfer system is ω. H At that time, i.e., strongly coupled mode:

[0128] The primary-side branch compensation capacitor C in the primary-side compensation network x And the original side branch compensation inductor L x The primary-side series compensation capacitor C forms a series resonant network. p1 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the first transmitting coil L in the coupling coil p1 The secondary-side series compensation capacitor C forms a series detuned network. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 and the receiving coil L in the coupling coil s This forms a series resonant network;

[0129] Specifically:

[0130]

[0131] In the formula, α is the primary-side detuning rate under strong coupling mode.

[0132] like Figure 3 As shown, the operating angular frequency of the frequency-reconfigurable wireless power transfer system is ω. L At this time, i.e., weakly coupled mode:

[0133] The primary-side branch compensation capacitor C in the primary-side compensation network x And the original side branch compensation inductor L x The series connection is equivalent to a compensation capacitor C. eq The primary-side series compensation capacitor C in the primary-side compensation network p1 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the first transmitting coil L in the coupling coil p1 The primary-side loop compensation capacitor C forms a series resonant network. p2 Primary branch compensation capacitor C x Primary branch compensation inductor L x and the second transmitting coil L in the coupling coil p2 A parallel resonant network is formed, wherein the secondary side of the secondary compensation network is connected in series with a compensation capacitor C. s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 and the receiving coil L in the coupling coil s This forms a series resonant network;

[0134] Specifically:

[0135]

[0136] The operating angular frequency of the frequency-reconfigurable wireless power transfer system is ω. H At that time, i.e., strongly coupled mode:

[0137] The system output power P under the strongly coupled mode oH The expression is as follows:

[0138]

[0139] The flow through the first transmitting coil L in the strongly coupled mode p1 Current I p1H The expression is as follows:

[0140]

[0141] Furthermore, when M p1s →0, I p1H equal:

[0142]

[0143] As can be seen from equation (5), when the receiving coil deviates from the allowable operating range or is completely removed, the current flowing through the transmitting coil will not increase exponentially, thus avoiding the risk of overcurrent in the transmitting coil.

[0144] The system input impedance Z under the strongly coupled mode inH and its phase angle θ inH The expression is as follows:

[0145]

[0146] From equation (6), it can be seen that the system input impedance Z inH If the switching transistor is inductive, it is possible to achieve zero-voltage turn-on of the inverter switch; in addition, the input impedance phase angle θ inH The range of variation can be represented as: β H This represents the coupling change factor under weakly coupled modes.

[0147] The system output power P in the weakly coupled mode oL The expression is as follows:

[0148]

[0149] The weakly coupled mode flows through the first transmitting coil L p1 Current I p1L and flowing through the second transmitting coil L p2 Current I p2L The expression is as follows:

[0150]

[0151] Furthermore, when M p1s →0,M p2s →0, I p1L and I p2L They are respectively equal to:

[0152]

[0153] As can be seen from equation (9), when the receiving coil deviates from the allowable operating range or is completely removed, the current flowing through the transmitting coil will not increase exponentially, thus avoiding the risk of overcurrent in the transmitting coil.

[0154] The system input impedance Z under the strongly coupled mode inL and its phase angle θ inL The expression is as follows:

[0155]

[0156] From equation (10), it can be seen that the system input impedance Z inL If the switching transistor is inductive, it is possible to achieve zero-voltage turn-on of the inverter switch; in addition, the input impedance phase angle θ inL The range of variation can be represented as: β L This represents the coupling change factor under weakly coupled modes.

[0157] In equations (3) to (10), C eq The capacitance value of the equivalent compensation capacitor of the primary branch, L p1 L is the self-inductance of the first transmitting coil. p2 The self-inductance value of the second transmitting coil, L s M is the self-inductance value of the receiving coil; p1s M is the main coupling mutual inductance value between the first transmitting coil and the receiving coil. p2s k is the main coupling mutual inductance value between the second transmitting coil and the receiving coil. p1s Let k be the coupling coefficient between the first transmitting coil and the receiving coil. p2s ω is the coupling coefficient between the second transmitting coil and the receiving coil. H The system operating angular frequency ω under strongly coupled modes L U is the system operating angular frequency in the weakly coupled mode; D The voltage value of the DC voltage source, U AB This represents the output voltage value of the full-bridge inverter circuit, and R o The resistance value of the battery load, R eq This is the equivalent AC resistance value before the rectifier and filter circuit, and j is the imaginary unit; α is the primary-side detuning rate in strongly coupled modes, and Where, k cri The critical coupling coefficient during frequency switching, β H This represents the coupling change factor under strongly coupled modes.

[0158] like Figure 4 As shown, this embodiment also provides a parameter design method for a frequency-reconfigurable wireless power transfer system, including the following steps:

[0159] Step 1: Set the system technical specifications according to actual operating conditions, including: DC input voltage U D Preset output power P oset Battery load R o System output power fluctuation ratio δ, system operating angular frequency ω under strongly coupled modes H ;

[0160] Step one specifically includes:

[0161] The system output power fluctuation ratio δ is defined as follows:

[0162]

[0163] Among them, P omax and P omin These are the maximum and minimum power values ​​that the frequency-reconfigurable wireless power transmission system is allowed to transmit, respectively, and they are defined to have the following relationship:

[0164]

[0165] In the formula, P oset The preset output power is set to a specific value; to prevent battery overvoltage or overcurrent, the preset output power P is set to a specific value. oset The design is based on the maximum power P that the system is allowed to transmit. omax Place.

[0166] Step 2: Based on the design requirements of the coupling coil in the frequency-reconfigurable wireless power transmission system, obtain the first transmitting coil L using finite element simulation software. p1 Second transmitting coil L p2 Receiver coil L s The self-induction value;

[0167] Step 3: Based on the set system output power fluctuation ratio δ, calculate the coupling change factor β under the strongly coupled mode. H Coupling variation factor β under weakly coupled modes L ;

[0168] Step three specifically includes:

[0169] like Figure 5 As shown, the coupling change factor β under the strongly coupled mode H The definition is as follows:

[0170]

[0171] Where, k max For the maximum working coupling coefficient, k cri Let be the critical coupling coefficient during frequency switching, and define the coupling change factor β under strongly coupled modes. H It can be calculated using the following formula:

[0172]

[0173] In the formula, δ H This refers to the system output power fluctuation ratio under strongly coupled modes;

[0174] The coupling change factor β under the weakly coupled modeL The definition is as follows:

[0175]

[0176] Where, k cri The critical coupling coefficient during frequency switching, k min The minimum working coupling coefficient is defined, and the coupling change factor β under weakly coupled modes is specified. L It can be calculated using the following formula:

[0177]

[0178] In the formula, δ L This represents the system output power fluctuation ratio under weakly coupled modes.

[0179] In practical design, to maximize the system's resistance to coupling coefficient fluctuations, the system output power fluctuation ratio δ under the strongly coupled mode is increased. H The system output power fluctuation ratio δ under the weakly coupled mode. L The values ​​are set to be equal;

[0180] Therefore, according to equations (14) and (16), the coupling change factor β under the strongly coupled mode is... H and the coupling change factor β under the weakly coupled mode L The values ​​are also equal:

[0181] β H =β L (17)

[0182] Step 4: Based on the obtained coupling change factor β H β L Calculate the equivalent compensation capacitance C of the original branch respectively. eq The system operating angular frequency ω under weakly coupled modes L ;

[0183] Step four specifically includes:

[0184] The equivalent compensation capacitor C of the primary side branch eq The calculation formula is as follows:

[0185]

[0186] In the formula, β H The coupling change factor under strongly coupled modes, L p1 The self-inductance of the first transmitting coil, ω H This refers to the system's operating angular frequency under strongly coupled modes;

[0187] The system operating angular frequency ω under the weakly coupled modeL The calculation formula is as follows:

[0188]

[0189] In the formula, β L The coupling change factor under weakly coupled modes, ω H This represents the system's operating angular frequency under strongly coupled modes.

[0190] Step 5: Determine the minimum operating coupling coefficient k in the system power-coupling curve. min Peak coupling coefficient k in weakly coupled modes exL Critical coupling coefficient k during frequency switching cri Peak coupling coefficient k in strongly coupled modes exH Maximum working coupling coefficient k max And the actual coupling change factor β o ;

[0191] Step five specifically includes:

[0192] The critical coupling coefficient k during frequency switching in the system power-coupling curve is described. cri The calculation formula is as follows:

[0193]

[0194] In the formula, C eq The capacitance value of the equivalent compensation capacitor of the primary branch, R o The resistance value of the battery load, ω H The system operating angular frequency ω under strongly coupled modes L For the system operating angular frequency in weakly coupled modes, L p1 L is the self-inductance of the first transmitting coil. s Let be the self-inductance value of the receiving coil, and define its relationship with other coupling coefficients in the curve as follows:

[0195]

[0196] In the formula, β H The coupling change factor and β under strongly coupled modes L The coupling change factor under weakly coupled modes, k min For the minimum working coupling coefficient, k exL The peak coupling coefficient, k, in the weakly coupled mode. exH The peak coupling coefficient, k, under strongly coupled modes max The maximum working coupling coefficient;

[0197] The actual coupling change factor β o The definition is as follows:

[0198]

[0199] Where, k max For the maximum working coupling coefficient, k min The minimum working coupling coefficient is defined, and the actual coupling variation factor β is specified. o It can be calculated using the following formula:

[0200] β o =β H β L (twenty three)

[0201] In the formula, β H The coupling change factor and β under strongly coupled modes L This represents the coupling change factor under weakly coupled modes.

[0202] Step Six: Based on the operating angular frequency ω of the frequency-reconfigurable wireless power transmission system... H and ω L The resonance conditions or relationships between the various compensation elements are determined, and the parameters of each compensation element are tuned accordingly.

[0203] Step six specifically includes:

[0204] The primary-side series compensation capacitor C in the primary-side compensation network p1 The calculation formula is as follows:

[0205]

[0206] The primary-side loop compensation capacitor C in the primary-side compensation network p2 The calculation formula is as follows:

[0207]

[0208] The primary-side branch compensation capacitor C in the primary-side compensation network x The calculation formula is as follows:

[0209]

[0210] The primary branch compensation inductor L in the primary compensation network x The calculation formula is as follows:

[0211]

[0212] The secondary-side series compensation capacitor C in the secondary-side compensation network s The range of values ​​for is as follows:

[0213]

[0214] The secondary loop compensation capacitor C in the secondary side compensation network s1 The calculation formula is as follows:

[0215]

[0216] The secondary loop compensation inductor L in the secondary compensation network s1 The calculation formula is as follows:

[0217]

[0218] In equations (24) to (30), C eq The capacitance value of the equivalent compensation capacitor of the primary branch, L p1 L is the self-inductance of the first transmitting coil. p2 The self-inductance value of the second transmitting coil, L s ω is the self-inductance of the receiving coil. H The system operating angular frequency ω under strongly coupled modes L The system operating angular frequency in the weakly coupled mode is ω. H =2πf H ω L =2πf L , where f H f L These represent the system operating frequencies in strongly coupled and weakly coupled modes, respectively.

[0219] To verify the correctness and feasibility of the parameter design method for the frequency-reconfigurable wireless power transfer system, a detailed parameter design process is given below with reference to a design example:

[0220] First, given the system's technical specifications and the self-inductance value of the coupling coil, see Table 1 for details:

[0221] Table 1 System technical specifications and self-inductance of coupling coils

[0222]

[0223] Based on the system output power fluctuation ratio δ shown in Table 1, the coupling change factor β under the strongly coupled mode can be obtained. H Coupling variation factor β under weakly coupled modes L :

[0224]

[0225] Then, the coupling change factor β under the strongly coupled mode. H Coupling variation factor β under weakly coupled modes L The equivalent compensation capacitor C of the primary branch can be calculated. eqThe system operating angular frequency ω under weakly coupled modes L :

[0226]

[0227] Next, the minimum operating coupling coefficient k in the system power-coupling curve can be determined from equations (20), (21), and (23). min Peak coupling coefficient k in weakly coupled modes exL Critical coupling coefficient k during frequency switching cri Peak coupling coefficient k in strongly coupled modes exH Maximum working coupling coefficient k max And the actual coupling change factor β o See Table 2 for details:

[0228] Table 2 shows the coupling coefficients and actual coupling variation factors in the system power-coupling curves.

[0229]

[0230] Furthermore, based on the resonance conditions or relationships between the compensation elements, i.e., equations (1) and (2), the parameters of each compensation element are tuned, as shown in Table 3. The secondary-side series compensation capacitor C... s The value range is 29.87nF to 48.11nF, and we take 39nF as an example here.

[0231] Table 3 Parameters of each compensation element in the system

[0232]

[0233] Finally, considering the system output power P under strongly coupled mode... oH The expression (3) and the system output power P under the weakly coupled mode. oL The expression (7) is obtained using Mathematica mathematical analysis software, as shown in the figure. Figure 6 The system power-coupling curve shown is a theoretically calculated graph. (From...) Figure 6 It can be seen that strongly coupled modes and weakly coupled modes differ in coupling coefficient k. p1s A perfect switch was achieved at a value of 0.2266, and when the coupling coefficient k... p1s When the coupling coefficient fluctuates between 0.1437 and 0.3570, that is, within the range of approximately 250%, the system output power ranges from 452.38W to 500W. The output power fluctuation is always within the set range of 5%, and the system achieves near-constant power transmission within a relatively wide range of coupling coefficient fluctuations.

[0234] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent substitutions, and improvements made to the above embodiments without departing from the scope of the present invention, based on the technical essence of the present invention and within the spirit and principles of the present invention, shall still fall within the protection scope of the present invention.

Claims

1. A frequency-reconfigurable wireless power transmission system, characterized in that, It includes a full-bridge inverter circuit, a primary-side compensation network, coupling coils, a secondary-side compensation network, and a rectifier filter circuit; The input terminal of the full-bridge inverter circuit is connected to a DC voltage source. U D The output of the full-bridge inverter circuit is connected to the input of the primary-side compensation network. The output of the primary-side compensation network is connected to the primary-side input of the coupling coil. The secondary-side output of the coupling coil is connected to the input of the secondary-side compensation network. The output of the secondary-side compensation network is connected to the input of the rectifier-filter circuit. The output of the rectifier-filter circuit is connected to the battery load. R o ; The primary-side compensation network consists of a primary-side compensation capacitor connected in series. C p1 Primary circuit compensation capacitor C p2 Primary branch compensation capacitor C x Original side branch compensation inductance L x constitute; The coupling coil consists of the first transmitting coil. L p1 Second transmitting coil L p2 Receiver coil L s constitute; The secondary-side compensation network consists of a secondary-side series compensation capacitor. C s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 constitute; Primary-side series compensation capacitor C p1 One end is connected to one output terminal of the full-bridge inverter circuit, and a compensation capacitor is connected in series on the primary side. C p1 The other end is connected to the first transmitting coil L p1 One end; Primary circuit compensation capacitor C p2 One end is connected to the other output terminal of the full-bridge inverter circuit and the primary branch compensation capacitor. C x One end is connected to the primary circuit compensation capacitor. C p2 The other end is connected to the second transmitting coil L p2 One end; Primary branch compensation capacitor C x One end is connected to the other output terminal of the full-bridge inverter circuit and the primary-side circuit compensation capacitor. C p2 One end is connected to the primary branch compensation capacitor. C x The other end is connected to the primary branch compensation inductor. L x One end; Primary branch compensation inductor L x One end is connected to the primary branch compensation capacitor. C x At the other end, the original side branch compensation inductor L x The other end is connected to the first transmitting coil L p1 The other end and the second transmitting coil L p2 The other end is connected; Secondary-side series compensation capacitor C s One end is connected to the receiving coil L s One end, a secondary side series compensation capacitor C s The other end is connected to one input terminal of the rectifier filter circuit; Secondary loop compensation capacitor C s1 One end is connected to the receiving coil L s The other end and the secondary loop compensation inductor L s1 One end is connected to the secondary loop compensation capacitor. C s1 The other end connects to the other input of the rectifier filter circuit and the secondary loop compensation inductor. L s1 The other end is connected; Secondary loop compensation inductor L s1 One end is connected to the receiving coil L s The other end and the secondary loop compensation capacitor C s1 One end is connected to the secondary loop compensation inductor. L s1 The other end connects to the other input terminal of the rectifier filter circuit and the secondary loop compensation capacitor. C s1 The other end is connected.

2. The frequency-reconfigurable wireless power transmission system according to claim 1, characterized in that, It also includes two operating angular frequencies , , and respectively correspond to strongly coupled mode and weakly coupled mode; The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is At that time, i.e., strongly coupled mode: The primary branch compensation capacitor in the primary-side compensation network C x Compensating inductance of the original side branch L x The primary-side series compensation capacitor constitutes a series resonant network. C p1 Primary branch compensation capacitor C x Original side branch compensation inductance L x and the first transmitting coil in the coupling coil L p1 The secondary-side series compensation capacitor constitutes a series detuned network. C s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 and the receiving coil in the coupling coil L s This forms a series resonant network; Specifically: In the formula, This represents the primary-side detuning rate in strongly coupled modes. The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is At this time, i.e., weakly coupled mode: The primary branch compensation capacitor in the primary-side compensation network C x Compensating inductance of the original side branch L x The series connection is equivalent to a compensation capacitor. C eq The primary-side series compensation capacitor in the primary-side compensation network C p1 Primary branch compensation capacitor C x Original side branch compensation inductance L x and the first transmitting coil in the coupling coil L p1 The primary-side loop compensation capacitor in the primary-side compensation network constitutes a series resonant network. C p2 Primary branch compensation capacitor C x Original side branch compensation inductance L x and the second transmitting coil in the coupling coil L p2 A parallel resonant network is formed, wherein the secondary side of the secondary compensation network is connected in series with a compensation capacitor. C s Secondary loop compensation capacitor C s1 Secondary loop compensation inductor L s1 and the receiving coil in the coupling coil L s This forms a series resonant network; Specifically: ; System output power in strongly coupled modes P oH The expression is as follows: Flow through the first transmitting coil in strongly coupled mode L p1 current I p1H The expression is as follows: System input impedance under strongly coupled modes Z inH and its phase angle θ inH The expression is as follows: The operating angular frequency of the variable frequency reconfigurable wireless power transfer system is At this time, i.e., weakly coupled mode: System output power in weakly coupled modes P oL The expression is as follows: The flow through the first transmitting coil in the weakly coupled mode L p1 current I p1L and flowing through the second transmitting coil L p2 current I p2L The expression is as follows: System input impedance in weakly coupled modes Z inL and its phase angle θ inL The expression is as follows: In the formula, , , , ; C eq The capacitance value of the equivalent compensation capacitor for the original branch. L p1 The self-inductance value of the first transmitting coil, L p2 The self-inductance of the second transmitting coil, L s This is the self-inductance value of the receiving coil; M p1s The main coupling mutual inductance value between the first transmitting coil and the receiving coil, M p2s This is the main coupling mutual inductance value between the second transmitting coil and the receiving coil; k p1s The coupling coefficient between the first transmitting coil and the receiving coil. k p2s This is the coupling coefficient between the second transmitting coil and the receiving coil; For the system operating angular frequency under strongly coupled modes, This refers to the system's operating angular frequency in the weakly coupled mode. U D The voltage value of the DC voltage source, U AB The output voltage value of the full-bridge inverter circuit, R o The resistance value of the battery load, R eq This is the equivalent AC resistance value before the rectifier and filter circuit; j The imaginary unit; denoted as the primary-side detuning rate in strongly coupled modes.

3. A parameter design method for a frequency-reconfigurable wireless power transmission system according to any one of claims 1 to 2, characterized in that, Specifically, the following steps are included: Step 1: Based on actual operating conditions, set the system technical specifications, including: DC input voltage. U D Preset output power P oset Battery load R o System output power fluctuation ratio The system operating angular frequency under strongly coupled modes ; Step 2: Based on the design requirements of the coupling coil in the frequency-reconfigurable wireless power transmission system, obtain the first transmitting coil using finite element simulation software. L p1 Second transmitting coil L p2 Receiver coil L s The self-induction value; Step 3: Based on the set system output power fluctuation ratio Calculate the coupling change factor under strongly coupled modes respectively. Coupling variation factor under weakly coupled modes ; Step 4: Based on the obtained coupling change factor , Calculate the equivalent compensation capacitance of the original branch respectively. C eq The operating angular frequency of the system under weakly coupled modes ; Step 5: Determine the minimum operating coupling coefficient in the system power-coupling curve. k min Peak coupling coefficient in weakly coupled modes k exL Critical coupling coefficient during frequency switching k cri Peak coupling coefficient in strongly coupled modes k exH Maximum working coupling coefficient k max And the actual coupling change factor ; Step 6: Based on the operating angular frequency of the frequency-reconfigurable wireless power transmission system... and The resonance conditions or relationships between the various compensation elements are determined, and the parameters of each compensation element are tuned accordingly.

4. The parameter design method for a frequency-reconfigurable wireless power transmission system according to claim 3, characterized in that, Step 1 specifically includes: System output power fluctuation ratio The definition is as follows: in, P omax and P omin These are the maximum and minimum power values ​​that the frequency-reconfigurable wireless power transmission system is allowed to transmit, respectively, and they are defined to have the following relationship: In the formula, P oset The preset output power is used to prevent battery overvoltage or overcurrent. P oset The design is based on the maximum power allowed to be transmitted by the system. P omax Place.

5. The parameter design method for a frequency-reconfigurable wireless power transmission system according to claim 3, characterized in that, Step 3 specifically includes Coupling variation factor in strongly coupled modes The definition is as follows: in, k max For the maximum working coupling coefficient, k cri The critical coupling coefficient during frequency switching is defined, and the coupling change factor under strongly coupled modes is specified. It can be calculated using the following formula: In the formula, This refers to the system output power fluctuation ratio under strongly coupled modes; Coupling variation factor in weakly coupled modes The definition is as follows: in, k cri The critical coupling coefficient during frequency switching k min The minimum working coupling coefficient is defined, and the coupling change factor under weakly coupled modes is specified. It can be calculated using the following formula: In the formula, This represents the system output power fluctuation ratio under weakly coupled modes.

6. The parameter design method for a frequency-reconfigurable wireless power transmission system according to claim 3, characterized in that, Step 4 specifically includes: Equivalent compensation capacitor of primary branch C eq The calculation formula is as follows: In the formula, The coupling change factor under strongly coupled modes, L p1 The self-inductance value of the first transmitting coil, This refers to the system's operating angular frequency under strongly coupled modes; System operating angular frequency in weakly coupled modes The calculation formula is as follows: In the formula, The coupling change factor under weakly coupled modes, This represents the system's operating angular frequency under strongly coupled modes.

7. The parameter design method for a frequency-reconfigurable wireless power transmission system according to claim 3, characterized in that, Step 5 specifically includes: Critical coupling coefficient during frequency switching in the system power-coupling curve k cri The calculation formula is as follows: In the formula, C eq The capacitance value of the equivalent compensation capacitor for the original branch. R o The resistance value of the battery load, For the system operating angular frequency under strongly coupled modes, For the system operating angular frequency in weakly coupled modes, L p1 The self-inductance value of the first transmitting coil, L s Let be the self-inductance value of the receiving coil, and define its relationship with other coupling coefficients in the curve as follows: In the formula, The coupling change factor under strongly coupled modes, The coupling change factor under weakly coupled modes, k min For minimum working coupling coefficient, k exL The peak coupling coefficient in the weakly coupled mode. k exH The peak coupling coefficient in strongly coupled modes, k max The maximum working coupling coefficient; Actual coupling change factor The definition is as follows: in, k max For the maximum working coupling coefficient, k min The minimum working coupling coefficient is defined, and the actual coupling variation factor is specified. It can be calculated using the following formula: In the formula, The coupling change factor under strongly coupled modes, This represents the coupling change factor under weakly coupled modes.

8. The parameter design method for a frequency-reconfigurable wireless power transmission system according to claim 3, characterized in that, Step 6 specifically includes: Primary-side series compensation capacitor in the primary-side compensation network C p1 The calculation formula is as follows: Primary-side loop compensation capacitor in the primary-side compensation network C p2 The calculation formula is as follows: Primary branch compensation capacitor in primary-side compensation network C x The calculation formula is as follows: Primary-side branch compensation inductance in primary-side compensation network L x The calculation formula is as follows: Secondary-side series compensation capacitor in the secondary-side compensation network C s The range of values ​​for is as follows: Secondary loop compensation capacitor in secondary compensation network C s1 The calculation formula is as follows: Secondary loop compensation inductor in secondary compensation network L s1 The calculation formula is as follows: In the formula, C eq The capacitance value of the equivalent compensation capacitor for the original branch. L p1 The self-inductance value of the first transmitting coil, L p2 The self-inductance of the second transmitting coil, L s This is the self-inductance value of the receiving coil; For the system operating angular frequency under strongly coupled modes, This represents the system's operating angular frequency in the weakly coupled mode.

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