Variable-frequency reconfigurable wireless power transmission system and parameter design method

Abstract

The invention discloses a variable-frequency reconfigurable wireless electric energy transmission system and a parameter design method, and relates to a wireless electric energy transmission system and a parameter design method. The invention aims to solve the problem that approximately constant power transmission is difficult to maintain in the prior art for relatively wide coupling coefficient fluctuation. The system comprises a full-bridge inverter circuit, a primary side compensation network, a coupling coil, a secondary side compensation network and a rectification filter circuit. The input end of the full-bridge inverter circuit is connected with a direct-current voltage source UD, the output end of the full-bridge inverter circuit is connected with the input end of the primary side compensation network, the output end of the primary side compensation network is connected with the primary side input end of the coupling coil, and the secondary side output end of the coupling coil is connected with the input end of the secondary side compensation network. The output end of the secondary side compensation network is connected with the input end of the rectification filter circuit, and the output end of the rectification filter circuit is connected with the battery load Ro. The invention belongs to the technical field of wireless power transmission.

Description

Technical Field

[0001] The invention relates to a wireless power transmission system and a parameter design method, belonging to the technical field of wireless power transmission. Background Art

[0002] Inductive Power Transfer (IPT) technology uses alternating electromagnetic fields as a medium to achieve non-physical contact transmission of energy from power source to load. It has the characteristics of safe, flexible and reliable power supply. It has been put into practical use in many fields such as electric vehicles, drones, and underwater detection. However, in most applications, the transmitting coil and the receiving coil are inevitably offset and misaligned, and the mutual inductance and coupling parameters between the coils fluctuate violently, which in turn has a significant impact on the stable power transmission of the IPT system.

[0003] In response to the above problems, domestic and foreign research teams have started their research from the aspects of closed-loop control technology and compensation topology design. Among them, for the anti-offset technology using control, the system output power is maintained most accurately; however, it is necessary to introduce an additional DC-DC converter, or perform phase shift control on the inverter module, and when it involves pulse frequency modulation, the system frequency splitting phenomenon is prone to occur, which greatly reduces the stability of the system; in addition, when the coupling coefficient fluctuates in a large range, the system control is relatively complex due to the limitation of the modulation margin. In order to reduce the control pressure and reduce the complexity of system control, some scholars have shifted their attention to the compensation topology design; for example, Southwest Jiaotong University proposed a hybrid topology of input parallel-output parallel type based on S-LCC and LCC-S, and the system output voltage can allow an offset of ±200mm in the X direction and -40mm in the Z direction under a fluctuation of 5%. However, when the receiving coil deviates from the allowed working range or is completely evacuated, the current flowing through the transmitting coil will surge exponentially, which will directly damage the system. At the same time, it uses 4 coupling coils, the magnetic structure is relatively complex, and it brings an increase in cost, volume, and weight to the system. Therefore, in the face of wide coupling coefficient fluctuations, how to maintain near-constant power transmission while reducing system control complexity is one of the key issues in IPT technology research. Summary of the invention

[0004] The present invention aims to solve the problem that the prior art is difficult to maintain nearly constant power transmission in the face of wide coupling coefficient fluctuations, and further proposes a frequency-variable reconfigurable wireless power transmission system and a parameter design method.

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

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

[0007] Furthermore, the primary compensation network includes a primary series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , primary branch compensation capacitor C x , primary branch compensation inductance L x ;

[0008] The coupling coil includes a first transmitting coil L p1 , the second transmitting coil L p2 , receiving coil L s ;

[0009] The secondary side compensation network includes the secondary side series compensation capacitor C s , secondary loop compensation capacitor C s1 , secondary loop compensation inductor L s1 .

[0010] Furthermore, in the primary side compensation network:

[0011] Primary side series compensation capacitor C p1 One end of the full-bridge inverter circuit is connected to an output end of the full-bridge inverter circuit, and the primary side is connected in series with a compensation capacitor C p1 The other end of the first transmitting coil L p1 One end of the connection;

[0012] Primary loop compensation capacitor C p2 One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C x One end and the primary branch compensation inductor L x One end of the primary circuit compensation capacitor C p2 The other end is connected to the second transmitting coil L p2 One end of the connection;

[0013] Primary branch compensation capacitor C x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation inductor L x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation capacitor C x The other end is connected to the primary branch compensation inductor L x The other end of the first transmitting coil Lp1 The other end and the second transmitting coil L p2 The other end is connected;

[0014] Primary branch compensation inductance L x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation inductor L x The other end of the primary branch compensation capacitor C x The other end of the first transmitting coil L p1 The other end of the second transmitting coil L p2 The other end of the connection.

[0015] Furthermore, in the secondary side compensation network:

[0016] Secondary side series compensation capacitor C s One end of the receiving coil L s One end is connected to the secondary side, and the compensation capacitor C is connected in series with the secondary side. s The other end is connected to an output end of the rectifier and filter circuit;

[0017] Secondary loop compensation capacitor C s1 One end of the receiving coil L s The other end and the secondary loop compensation inductor L s1 One end of the secondary loop compensation capacitor C s1 The other end is connected to the other output end of the rectifier filter circuit and the secondary loop compensation inductor L s1 The other end is connected;

[0018] Secondary loop compensation inductor L s1 One end of the receiving coil L s The other end and the secondary loop compensation capacitor C s1 One end of the secondary loop compensation inductor L s1 The other end is connected to the other output end of the rectifier filter circuit and the secondary loop compensation capacitor C s1 The other end of the connection.

[0019] The specific steps of the parameter design method of the present invention include:

[0020] Step 1: According to the actual working conditions, set the system technical indicators, 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 strong coupling mode H ;

[0021] Step 2: According to the design requirements of the coupling coil in the frequency-converting reconfigurable wireless power transmission system, the first transmitting coil L is obtained by finite element simulation software. p1 , the second transmitting coil L p2 , receiving coil L s The self-inductance value;

[0022] Step 3: Calculate the coupling variation factor β under the strong coupling mode according to the set system output power fluctuation ratio δ. H , coupling change factor β under weak coupling mode L ;

[0023] Step 4: According to the obtained coupling change factor β H , β L , calculate the equivalent compensation inductance L of the primary branch respectively eq , the system operating angular frequency ω in weak coupling mode L ;

[0024] Step 5: Determine the minimum working coupling coefficient k in the system power-coupling curve min , peak coupling coefficient k in weak coupling mode exL , critical coupling coefficient k during frequency switching cri , peak coupling coefficient k in strong coupling mode exH , maximum working coupling coefficient k max And the actual coupling change factor β o ;

[0025] Step 6: According to the working angular frequency ω in the frequency-converting reconfigurable wireless power transmission system H and ω L The resonance conditions or relationships between the compensation components are determined to complete the adjustment of the parameters of each compensation component.

[0026] Furthermore, step 1 specifically includes:

[0027] The definition of system output power fluctuation ratio δ is as follows:

[0028]

[0029] In formula (1), P omax represents the maximum power allowed to be transmitted by the frequency-variable reconfigurable wireless power transmission system and P omin It indicates the minimum power value allowed to be transmitted by the frequency-convertible reconfigurable wireless power transmission system, and stipulates that they have the following relationship:

[0030]

[0031] In formula (2), P osetIndicates the preset output power; in order to prevent the battery from overvoltage or overcurrent, the preset output power P oset Design the maximum power P that the system allows to transmit omax Place.

[0032] Furthermore, step 3 specifically includes:

[0033] Coupling change factor β in strong coupling mode H The definition is as follows:

[0034]

[0035] In formula (3), k max Indicates the maximum working coupling coefficient, k cri It represents the critical coupling coefficient when the frequency is switched, and specifies the coupling change factor β under the strong coupling mode. H It can be calculated by the following formula:

[0036]

[0037] In formula (4), δ H represents the system output power fluctuation ratio under the strong coupling mode;

[0038] Coupling change factor β in weak coupling mode L The definition is as follows:

[0039]

[0040] In formula (5), k cri represents the critical coupling coefficient when switching frequencies, k min Indicates the minimum working coupling coefficient and specifies the coupling change factor β under the weak coupling mode L It can be calculated by the following formula:

[0041]

[0042] In formula (6), δ L Represents the system output power fluctuation ratio in the weakly coupled mode.

[0043] Furthermore, step 4 specifically includes:

[0044] Primary branch equivalent compensation inductance L eq The calculation formula is as follows:

[0045] L eq =(β H -1)L p1 (7)

[0046] In formula (7), β HIndicates the coupling change factor under strong coupling mode, L p1 represents the self-inductance value of the first transmitting coil;

[0047] The system operating angular frequency ω in weak coupling mode L The calculation formula is as follows:

[0048] ω L =β L ω H (8)

[0049] In formula (8), β L Indicates the coupling change multiple in the weak coupling mode, ω H represents the system operating angular frequency in the strong coupling mode.

[0050] Furthermore, step 5 specifically includes:

[0051] Critical coupling coefficient k when frequency switching in the system power-coupling curve cri The calculation formula is as follows:

[0052]

[0053] In formula (9), L eq Indicates the inductance value of the equivalent compensation inductance of the primary branch, R o Represents the resistance value of the battery load, ω L represents the system operating angular frequency in the weak coupling mode, L p1 represents the self-inductance of the first transmitting coil, L s It represents the self-inductance of the receiving coil and stipulates that it has the following relationship with other coupling coefficients in the curve:

[0054]

[0055] In formula (10), β H represents the coupling change factor in the strong coupling mode, β L represents the coupling change factor in the weak coupling mode, k min Indicates the minimum working coupling coefficient, k exL represents the peak coupling coefficient in the weak coupling mode, k exH represents the peak coupling coefficient in the strong coupling mode, k max Indicates the maximum working coupling coefficient;

[0056] The actual coupling change factor β o The definition is as follows:

[0057]

[0058] In formula (11), k maxIndicates the maximum working coupling coefficient, k min Indicates the minimum working coupling coefficient and specifies the actual coupling change multiple β o It can be calculated by the following formula:

[0059] β o =β H β L (12)

[0060] In formula (12), β H represents the coupling change factor in the strong coupling mode, β L Indicates the coupling change factor in the weakly coupled mode.

[0061] Furthermore, step 6 specifically includes:

[0062] The primary side series compensation capacitor C in the primary side compensation network p1 The calculation formula is as follows:

[0063]

[0064] The primary loop compensation capacitor C in the primary compensation network p2 The calculation formula is as follows:

[0065]

[0066] Primary branch compensation capacitor C in the primary compensation network x The calculation formula is as follows:

[0067]

[0068] The primary branch compensation inductor L in the primary compensation network x The calculation formula is as follows:

[0069]

[0070] Secondary side series compensation capacitor C in the secondary side compensation network s The value range of is as follows:

[0071]

[0072] The secondary loop compensation capacitor C in the secondary compensation network s1 The calculation formula is as follows:

[0073]

[0074] The secondary loop compensation inductor L in the secondary compensation network s1 The calculation formula is as follows:

[0075]

[0076] In formula (13) to formula (19), L eq Indicates the inductance value of the equivalent compensation inductance of the primary branch, L p1 represents the self-inductance of the first transmitting coil, L p2 Represents the self-inductance of the second transmitting coil, L s Represents the self-inductance of the receiving coil, ω H represents the system operating angular frequency in the strong coupling mode, ω L represents the system operating angular frequency in the weakly coupled mode.

[0077] The beneficial effects of the present invention are:

[0078] 1. The present invention can reconfigure the equivalent topological structure of the primary compensation network by switching the operating frequency of the system, and the secondary compensation network is always equivalent to a series resonant network, thereby realizing the switching between the strong coupling mode and the weak coupling mode, and connecting two different coupling coefficient fluctuation ranges end to end;

[0079] 2. The present invention can maintain nearly constant power transmission within a wide coupling coefficient fluctuation range without adding any control unit or AC switch, while avoiding the risk of overcurrent in the transmitting coil, and the inverter switch tube always maintains zero voltage conduction;

[0080] 3. The frequency-variable reconfigurable wireless power transmission system parameter design method described in the present invention does not require any additional loop iteration or optimization algorithm, and can directly perform value assignment calculations, thereby achieving rapid determination of all system parameters and simplifying the system parameter design steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 Schematic diagram of the overall architecture of a frequency-convertible reconfigurable wireless power transmission system according to an embodiment of the present invention;

[0082] Figure 2 The system operating angular frequency in the embodiment of the present invention is ω H When , it is the system equivalent circuit diagram under the strong coupling mode;

[0083] Figure 3 The system operating angular frequency in the embodiment of the present invention is ω L When , it is the system equivalent circuit diagram under weak coupling mode;

[0084] Figure 4 is a flow chart of the steps of a method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system in an embodiment of the present invention;

[0085] Figure 5 is a schematic diagram of the design of the system power-coupling curve in an embodiment of the present invention;

[0086] Figure 6 It is a theoretical calculation diagram of the system power-coupling curve in the embodiment of the present invention. DETAILED DESCRIPTION

[0087] Specific implementation method 1: Figures 1 to 3 As shown, a frequency-converting reconfigurable wireless power transmission system includes a full-bridge inverter circuit, a primary compensation network, a coupling coil, a secondary compensation network and a rectifier filter circuit;

[0088] The input end of the full-bridge inverter circuit is connected to the DC voltage source U D The output of the full-bridge inverter circuit is connected to the input of the primary compensation network, the output of the primary compensation network is connected to the primary input of the coupling coil, the secondary output of the coupling coil is connected to the input of the secondary compensation network, the output of the secondary compensation network is connected to the input of the rectifier filter circuit, and the output of the rectifier filter circuit is connected to the battery load R o connect.

[0089] Specific implementation method 2: Figures 1 to 3 As shown, based on the specific implementation mode 1, the primary compensation network includes a primary series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , primary branch compensation capacitor C x , primary branch compensation inductance L x ;

[0090] The coupling coil includes a first transmitting coil L p1 , the second transmitting coil L p2 , receiving coil L s ;

[0091] The secondary side compensation network includes the secondary side series compensation capacitor C s , secondary loop compensation capacitor C s1 , secondary loop compensation inductor L s1 .

[0092] Specific implementation method three: Figures 1 to 3 As shown, based on the second specific implementation mode, in the primary side compensation network:

[0093] Primary side series compensation capacitor C p1 One end of the full-bridge inverter circuit is connected to an output end of the full-bridge inverter circuit, and the primary side is connected in series with a compensation capacitor C p1 The other end of the first transmitting coil L p1 One end of the connection;

[0094] Primary loop compensation capacitor C p2 One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C xOne end and the primary branch compensation inductor L x One end of the primary circuit compensation capacitor C p2 The other end is connected to the second transmitting coil L p2 One end of the connection;

[0095] Primary branch compensation capacitor C x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation inductor L x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation capacitor C x The other end is connected to the primary branch compensation inductor L x The other end of the first transmitting coil L p1 The other end of the second transmitting coil L p2 The other end is connected;

[0096] Primary branch compensation inductance L x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation inductor L x The other end of the primary branch compensation capacitor C x The other end of the first transmitting coil L p1 The other end of the second transmitting coil L p2 The other end of the connection.

[0097] Specific implementation method four: Figures 1 to 3 As shown, based on the specific implementation mode 3, in the secondary side compensation network:

[0098] Secondary side series compensation capacitor C s One end of the receiving coil L s One end is connected to the secondary side, and the compensation capacitor C is connected in series with the secondary side. s The other end is connected to an output end of the rectifier and filter circuit;

[0099] Secondary loop compensation capacitor C s1 One end of the receiving coil L s The other end and the secondary loop compensation inductor L s1 One end of the secondary loop compensation capacitor C s1 The other end is connected to the other output end of the rectifier filter circuit and the secondary loop compensation inductor L s1 The other end is connected;

[0100] Secondary loop compensation inductor L s1 One end of the receiving coil L s The other end and the secondary loop compensation capacitor C s1One end of the secondary loop compensation inductor L s1 The other end is connected to the other output end of the rectifier filter circuit and the secondary loop compensation capacitor C s1 The other end of the connection.

[0101] Among them, the first transmitting coil L p1 With the second transmitting coil L p2 In a natural decoupling state, that is, the first transmitting coil L p1 With the second transmitting coil L p2 The cross-coupling mutual inductance M p1p2 It is equal to zero under normal working conditions;

[0102] The first transmitting coil L p1 With the receiving coil L s The main coupling mutual inductance M p1s Under normal working conditions, it is not zero; the second transmitting coil L p2 With the receiving coil L s The main coupling mutual inductance M p2s It is not zero under normal operating conditions.

[0103] The first transmitting coil L p1 and the second transmitting coil L p2 The self-inductance is equal to that of the main coupling mutual inductance M p1s and the main coupling mutual inductance M p2s The magnitudes are equal and the polarities are the same.

[0104] like Figure 2 and Figure 3 As shown, the frequency-variable reconfigurable wireless power transmission system has two operating angular frequencies ω H ,ω L , and correspond to the strong coupling mode and the weak coupling mode respectively.

[0105] like Figure 2 As shown, the operating angular frequency of the variable frequency reconfigurable wireless power transmission system is ω H When , that is, the strongly coupled mode:

[0106] Primary branch compensation capacitor C in the primary compensation network x And the primary branch compensation inductor L x The parallel connection is equivalent to a compensation inductor L eq , the primary series compensation capacitor C in the primary compensation network p1 , primary branch compensation capacitor C x , primary branch compensation inductance L x and the first transmitting coil L in the coupling coil p1 The series resonant network is formed, and the primary circuit compensation capacitor C in the primary compensation network p2, primary branch compensation capacitor C x , primary branch compensation inductance L x and the second transmitting coil L in the coupling coil p2 The secondary side series compensation capacitor C in the secondary side compensation network forms a parallel resonant network. s , secondary loop compensation capacitor C s1 , secondary loop compensation inductor L s1 and the receiving coil L in the coupling coil s Form a series resonant network;

[0107] Specifically:

[0108]

[0109] like Figure 3 As shown, the operating angular frequency of the variable frequency reconfigurable wireless power transmission system is ω L When , that is, weakly coupled mode:

[0110] The primary branch compensation capacitor C in the primary compensation network x And the primary branch compensation inductor L x A parallel resonant network is formed, wherein the primary side series compensation capacitor C in the primary side compensation network p1 , primary circuit compensation capacitor C p2 and the first transmitting coil L in the coupling coil p1 , the second transmitting coil L p2 A series detuned network is formed, wherein the secondary side series 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 Form a series resonant network;

[0111] Specifically:

[0112]

[0113] Where α is the primary side detuning rate in the weak coupling mode.

[0114] The operating angular frequency of the variable frequency reconfigurable wireless power transmission system is ω H When , that is, the strongly coupled mode:

[0115] The system output power P in the strong coupling mode oH The expression is as follows:

[0116]

[0117] The strong coupling mode flows through the first transmitting coil Lp1 The current I p1H and flows through the second transmitting coil L p2 The current I p2H The expression is as follows:

[0118]

[0119] Furthermore, when M p1s →0,M p2s →0, I p1H and I p2H are respectively equal to:

[0120]

[0121] It can be seen from formula (5) that when the receiving coil deviates from the allowed working range or is completely evacuated, the current flowing through the transmitting coil will not increase exponentially, thus avoiding the risk of overcurrent in the transmitting coil.

[0122] The system input impedance Z in the strong coupling mode inH and its phase angle θ inH The expression is as follows:

[0123]

[0124] From formula (6), we can know that the system input impedance Z inH Inductive, it is expected to achieve zero voltage conduction of the inverter switch tube; in addition, the input impedance phase angle θ inH The variation range of can be expressed as: β H is the coupling change multiple in the strong coupling mode.

[0125] The operating angular frequency of the variable frequency reconfigurable wireless power transmission system is ω L When , that is, weakly coupled mode:

[0126] The system output power P in the weak coupling mode oL The expression is as follows:

[0127]

[0128] The current flowing through the first transmitting coil L in the weak coupling mode p1 The current I p1L and flows through the second transmitting coil L p2 The current I p2L The expression is as follows:

[0129]

[0130] Furthermore, when M p1s →0,M p2s→0, I p1L and I p2L equal:

[0131]

[0132] It can be seen from formula (9) that when the receiving coil deviates from the allowed working range or is completely evacuated, the current flowing through the transmitting coil will not increase exponentially, thus avoiding the risk of overcurrent in the transmitting coil.

[0133] The system input impedance Z in the weak coupling mode inL and its phase angle θ inL The expression is as follows:

[0134]

[0135] From formula (10), we can know that the system input impedance Z inL Inductive, it is expected to achieve zero voltage conduction of the inverter switch tube; in addition, the input impedance phase angle θ inL The variation range of can be expressed as: β L is the coupling change multiple in the weak coupling mode.

[0136] In formula (3) to formula (10), L eq is the inductance value of the equivalent compensation inductor of the primary branch, L p1 is the self-inductance of the first transmitting coil, L p2 is the self-inductance of the second transmitting coil, L s is the self-inductance of the receiving coil; M p1s is the main coupling mutual inductance between the first transmitting coil and the receiving coil, M p2s k is the main coupling mutual inductance between the second transmitting coil and the receiving coil; p1s is the coupling coefficient between the first transmitting coil and the receiving coil, k p2s is the coupling coefficient between the second transmitting coil and the receiving coil; ω H is the system operating angular frequency in the strong coupling mode, ω L is the system operating angular frequency in weak coupling mode; U D is the voltage value of the DC voltage source, U AB is the output voltage value of the full-bridge inverter circuit, and R o is the resistance value of the battery load, R eq is the equivalent AC resistance value before the rectifier and filter circuit, and j is an imaginary unit; α is the primary side detuning ratio in the weak coupling mode, and Among them, k criis the critical coupling coefficient during frequency switching, β L is the coupling change multiple in the weak coupling mode.

[0137] Specific implementation method five: Figures 4 to 6 As shown, a frequency-variable reconfigurable wireless power transmission system parameter design method specifically includes:

[0138] Step 1: According to the actual working conditions, set the system technical indicators, 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 strong coupling mode H ;

[0139] Step 1 specifically includes:

[0140] The system output power fluctuation ratio δ is defined as follows:

[0141]

[0142] Among them, P omax and P omin are the maximum and minimum values ​​of the power allowed to be transmitted by the frequency-convertible reconfigurable wireless power transmission system, and it is stipulated that they have the following relationship:

[0143]

[0144] Where P oset is the preset output power; in order to prevent the battery from overvoltage or overcurrent, the preset output power P oset Design the maximum power P that the system allows to transmit omax Place.

[0145] Step 2: According to the design requirements of the coupling coil in the frequency-converting reconfigurable wireless power transmission system, the first transmitting coil L is obtained by finite element simulation software. p1 , the second transmitting coil L p2 , receiving coil L s The self-inductance value;

[0146] Step 3: According to the set system output power fluctuation ratio δ, calculate the coupling change multiple β under the strong coupling mode H , coupling change factor β under weak coupling mode L ;

[0147] Step three specifically includes:

[0148] like Figure 5 As shown, the coupling change factor β under the strong coupling mode HThe definition is as follows:

[0149]

[0150] Among them, k max is the maximum working coupling coefficient, k cri is the critical coupling coefficient when the frequency is switched, and specifies the coupling change factor β under the strong coupling mode H It can be calculated by the following formula:

[0151]

[0152] In the formula, δ H is the system output power fluctuation ratio under the strong coupling mode;

[0153] The coupling change factor β under the weak coupling mode L The definition is as follows:

[0154]

[0155] Among them, k cri is the critical coupling coefficient during frequency switching, k min is the minimum working coupling coefficient, and specifies the coupling change factor β under the weak coupling mode L It can be calculated by the following formula:

[0156]

[0157] In the formula, δ L is the system output power fluctuation ratio under weak coupling mode.

[0158] In the actual design, in order to maximize the system's ability to resist coupling coefficient fluctuations, the system output power fluctuation ratio under the strong coupling mode is δ H and the system output power fluctuation ratio δ under the weak coupling mode L The values ​​of are set to be equal;

[0159] Therefore, according to equations (14) and (16), the coupling change factor β under the strong coupling mode is H and the coupling change factor β under the weak coupling mode L The values ​​of are also equal:

[0160] β H =β L (17)

[0161] Step 4: According to the obtained coupling change factor β H , β L , calculate the equivalent compensation inductance L of the primary branch respectively eq, the system operating angular frequency ω in weak coupling mode L ;

[0162] Step 4 specifically includes:

[0163] The primary branch equivalent compensation inductance L eq The calculation formula is as follows:

[0164] L eq =(β H -1)L p1 (18)

[0165] In the formula, β H is the coupling change factor under the strong coupling mode, L p1 is the self-inductance value of the first transmitting coil;

[0166] The system operating angular frequency ω under the weak coupling mode L The calculation formula is as follows:

[0167] ω L =β L ω H (19)

[0168] In the formula, β L is the coupling change multiple under weak coupling mode, ω H is the system operating angular frequency in the strong coupling mode.

[0169] Step 5: Determine the minimum operating coupling coefficient k in the system power-coupling curve min , peak coupling coefficient k in weak coupling mode exL , critical coupling coefficient k during frequency switching cri , peak coupling coefficient k in strong coupling mode exH , maximum working coupling coefficient k max And the actual coupling change factor β o ;

[0170] Step 5 specifically includes:

[0171] The critical coupling coefficient k when the frequency is switched in the system power-coupling curve cri The calculation formula is as follows:

[0172]

[0173] Where, L eq is the inductance value of the equivalent compensation inductor of the primary branch, R o is the resistance value of the battery load, ω L is the system operating angular frequency in weak coupling mode, L p1 is the self-inductance of the first transmitting coil, Ls is the self-inductance of the receiving coil, and specifies it with Figure 5 The other coupling coefficients in the curves shown have the following relationships:

[0174]

[0175] In the formula, β H is the coupling change factor under the strong coupling mode, β L is the coupling change factor in the weak coupling mode, k min is the minimum working coupling coefficient, k exL is the peak coupling coefficient in the weak coupling mode, k exH is the peak coupling coefficient in the strong coupling mode, k max is the maximum working coupling coefficient;

[0176] The actual coupling change factor β o The definition is as follows:

[0177]

[0178] Among them, k max is the maximum working coupling coefficient, k min is the minimum working coupling coefficient, and specifies the actual coupling change multiple β o It can be calculated by the following formula:

[0179] β o =β H β L (twenty three)

[0180] In the formula, β H is the coupling change factor under the strong coupling mode, β L is the coupling change multiple in the weak coupling mode.

[0181] Step 6: According to the working angular frequency ω in the frequency-converting reconfigurable wireless power transmission system H and ω L The resonance conditions or relationships between the compensation components are determined to complete the adjustment of the parameters of each compensation component.

[0182] Step 6 specifically includes:

[0183] The primary side series compensation capacitor C in the primary side compensation network p1 The calculation formula is as follows:

[0184]

[0185] The primary loop compensation capacitor C in the primary compensation network p2 The calculation formula is as follows:

[0186]

[0187] The primary branch compensation capacitor C in the primary compensation network x The calculation formula is as follows:

[0188]

[0189] The primary branch compensation inductor L in the primary compensation network x The calculation formula is as follows:

[0190]

[0191] The secondary side series compensation capacitor C in the secondary side compensation network s The value range of is as follows:

[0192]

[0193] The secondary loop compensation capacitor C in the secondary compensation network s1 The calculation formula is as follows:

[0194]

[0195] The secondary loop compensation inductor L in the secondary compensation network s1 The calculation formula is as follows:

[0196]

[0197] In formula (24) to formula (30), L eq is the inductance value of the equivalent compensation inductor of the primary branch, L p1 is the self-inductance of the first transmitting coil, L p2 is the self-inductance of the second transmitting coil, L s is the self-inductance of the receiving coil; ω H is the system operating angular frequency in the strong coupling mode, ω L is the system operating angular frequency in the weak coupling mode, that is, ω H =2πf H ,ω L =2πf L , where f H 、f L are the system operating frequencies in strong coupling mode and weak coupling mode, respectively.

[0198] In order to verify the correctness and feasibility of the frequency-converting reconfigurable wireless power transmission system parameter design method, a detailed parameter design process is given below in combination with a design example:

[0199] First, given the system technical indicators and the self-inductance value of the coupling coil, see Table 1 for details:

[0200] Table 1 System technical indicators and self-inductance of coupling coil

[0201]

[0202] According to the system output power fluctuation ratio δ shown in Table 1, the coupling change multiple β under the strong coupling mode can be obtained. H , coupling change factor β under weak coupling mode L :

[0203]

[0204] Then, the coupling change factor β in the strong coupling mode is H , coupling change factor β under weak coupling mode L , the equivalent compensation inductance L of the primary branch can be calculated eq , the system operating angular frequency ω in weak coupling mode L :

[0205] L eq =(β H -1)L p1 =57.70μH

[0206]

[0207] Then, the minimum working coupling coefficient k in the system power-coupling curve can be determined by equations (20), (21), and (23): min , peak coupling coefficient k in weak coupling mode exL , critical coupling coefficient k during frequency switching cri , peak coupling coefficient k in strong coupling mode exH , maximum working coupling coefficient k max And the actual coupling change factor β o , as shown in Table 2:

[0208] Table 2 The coupling coefficients in the system power-coupling curve and the actual coupling change multiples

[0209]

[0210]

[0211] Furthermore, according to the resonance conditions or relationships between the compensation components, that is, equations (1) and (2), the parameters of the compensation components are adjusted, as shown in Table 3. s The value range is 11.79nF to 29.29nF, here we take 20nF as an example.

[0212] Table 3 Parameters of compensation components in the system

[0213]

[0214] Finally, combined with the system output power P in the strong coupling mode oH The expression (3) and the system output power P in the weak coupling mode are oL The expression (7) is obtained by using Mathematica mathematical analysis software: Figure 6 The theoretical calculation diagram of the system power-coupling curve is shown in Figure 2. Figure 5 and Figure 6 It can be seen that in order to meet the technical indicator requirement of the system output power fluctuation ratio δ of 5%, when the system operating frequency is f L When the coupling coefficient k p1s It can vary between 0.0966 and 0.1522; when the system operating frequency is f H When the coupling coefficient k p1s It can vary between 0.1522 and 0.2399, that is, two different coupling coefficient fluctuation ranges are connected end to end.

[0215] In summary, when the system operating frequency f L The coupling coefficient k p1s Switch to f at 0.1522 H When the weak coupling mode switches to the strong coupling mode, the coupling coefficient k p1s It can fluctuate between 0.0966 and 0.2399, that is, the coupling coefficient fluctuates within a range close to 250%. The system output power range is 452.38W to 500W, and the output power fluctuation is always within the set 5%. Therefore, the present invention achieves nearly constant power transmission within a wider coupling coefficient fluctuation range.

[0216] The above is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement made to the above embodiments without departing from the content of the technical solution of the present invention, based on the technical essence of the present invention, within the spirit and principles of the present invention, still fall within the protection scope of the technical solution of the present invention.

Claims

1. A frequency-convertible reconfigurable wireless power transmission system, characterized in that: It includes a full-bridge inverter circuit, a primary compensation network, a coupling coil, a secondary compensation network and a rectifier filter circuit; The input end of the full-bridge inverter circuit is connected to the DC voltage source U D The output of the full-bridge inverter circuit is connected to the input of the primary compensation network, the output of the primary compensation network is connected to the primary input of the coupling coil, the secondary output of the coupling coil is connected to the input of the secondary compensation network, the output of the secondary compensation network is connected to the input of the rectifier filter circuit, and the output of the rectifier filter circuit is connected to the battery load R o connect.

2. A frequency-convertible reconfigurable wireless power transmission system according to claim 1, characterized in that: The primary compensation network includes the primary series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , primary branch compensation capacitor C x , primary branch compensation inductance L x ; The coupling coil includes a first transmitting coil L p1 , the second transmitting coil L p2 , receiving coil L s ; The secondary side compensation network includes the secondary side series compensation capacitor C s , secondary loop compensation capacitor C s1 , secondary loop compensation inductor L s1 .

3. The frequency-convertible reconfigurable wireless power transmission system according to claim 2, characterized in that: In the primary side compensation network: Primary side series compensation capacitor C p1 One end of the full-bridge inverter circuit is connected to an output end of the full-bridge inverter circuit, and the primary side is connected in series with a compensation capacitor C p1 The other end of the first transmitting coil L p1 One end of the connection; Primary loop compensation capacitor C p2 One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C x One end and the primary branch compensation inductor L x One end of the primary circuit compensation capacitor C p2 The other end is connected to the second transmitting coil L p2 One end of the connection; Primary branch compensation capacitor C x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation inductor L x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation capacitor C x The other end is connected to the primary branch compensation inductor L x The other end of the first transmitting coil L p1 The other end of the second transmitting coil L p2 The other end is connected; Primary branch compensation inductance L x One end of the full-bridge inverter circuit is connected to the other output end and the primary branch compensation capacitor C x One end and the primary circuit compensation capacitor C p2 One end of the primary branch compensation inductor L x The other end of the primary branch compensation capacitor C x The other end of the first transmitting coil L p1 The other end of the second transmitting coil L p2 The other end of the connection.

4. The frequency-convertible reconfigurable wireless power transmission system according to claim 2, characterized in that: In the secondary side compensation network: Secondary side series compensation capacitor C s One end of the receiving coil L s One end is connected to the secondary side, and the compensation capacitor C is connected in series with the secondary side. s The other end is connected to an output end of the rectifier and filter circuit; Secondary loop compensation capacitor C s1 One end of the receiving coil L s The other end and the secondary loop compensation inductor L s1 One end of the secondary loop compensation capacitor C s1 The other end is connected to the other output end 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 of the receiving coil L s The other end and the secondary loop compensation capacitor C s1 One end of the secondary loop compensation inductor L s1 The other end is connected to the other output end of the rectifier filter circuit and the secondary loop compensation capacitor C s1 The other end of the connection.

5. A method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system, characterized in that: Specifically include: Step 1: According to the actual working conditions, set the system technical indicators, 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 strong coupling mode H ; Step 2: According to the design requirements of the coupling coil in the frequency-converting reconfigurable wireless power transmission system, the first transmitting coil L is obtained by finite element simulation software. p1 , the second transmitting coil L p2 , receiving coil L s The self-inductance value; Step 3: Calculate the coupling variation multiple β under the strong coupling mode according to the set system output power fluctuation ratio δ H , coupling change factor β under weak coupling mode L ; Step 4: According to the obtained coupling change factor β H , β L , calculate the equivalent compensation inductance L of the primary branch respectively eq , the system operating angular frequency ω in weak coupling mode L ; Step 5: Determine the minimum working coupling coefficient k in the system power-coupling curve min , peak coupling coefficient k in weak coupling mode exL , critical coupling coefficient k during frequency switching cri , peak coupling coefficient k in strong coupling mode exH , maximum working coupling coefficient k max And the actual coupling change factor β o ; Step 6: According to the working angular frequency ω in the frequency-converting reconfigurable wireless power transmission system H and ω L The resonance conditions or relationships between the compensation components are determined to complete the adjustment of the parameters of each compensation component.

6. A frequency-converting reconfigurable wireless power transmission system parameter design method according to claim 5, characterized in that: Step 1 specifically includes: The definition of system output power fluctuation ratio δ is as follows: In formula (1), P omax represents the maximum power allowed to be transmitted by the frequency-convertible reconfigurable wireless power transmission system, P omin It indicates the minimum power value allowed to be transmitted by the frequency-convertible reconfigurable wireless power transmission system, and stipulates that they have the following relationship: In formula (2), P oset Indicates the preset output power; in order to prevent the battery from overvoltage or overcurrent, the preset output power P oset Design the maximum power P that the system allows to transmit omax Place.

7. The method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system according to claim 5, characterized in that: Step 3 specifically includes: Coupling change factor β in strong coupling mode H The definition is as follows: In formula (3), k max Indicates the maximum working coupling coefficient, k cri It represents the critical coupling coefficient when the frequency is switched, and specifies the coupling change factor β under the strong coupling mode. H It can be calculated by the following formula: In formula (4), δ H represents the system output power fluctuation ratio under the strong coupling mode; Coupling change factor β in weak coupling mode L The definition is as follows: In formula (5), k cri represents the critical coupling coefficient when switching frequencies, k min Indicates the minimum working coupling coefficient and specifies the coupling change factor β under the weak coupling mode L It can be calculated by the following formula: In formula (6), δ L Represents the system output power fluctuation ratio in the weakly coupled mode.

8. The method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system according to claim 5, characterized in that: Step 4 specifically includes: Primary branch equivalent compensation inductance L eq The calculation formula is as follows: L eq =(β H -1)L p1 (7), In formula (7), β H Indicates the coupling change factor in the strong coupling mode, L p1 represents the self-inductance value of the first transmitting coil; The system operating angular frequency ω in weak coupling mode L The calculation formula is as follows: oh L =b L oh H (8), In formula (8), β L Indicates the coupling change multiple in the weak coupling mode, ω H represents the system operating angular frequency in the strong coupling mode.

9. The method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system according to claim 5, characterized in that: Step 5 specifically includes: Critical coupling coefficient k when frequency switching in the system power-coupling curve cri The calculation formula is as follows: In formula (9), L eq Indicates the inductance value of the equivalent compensation inductance of the primary branch, R o Represents the resistance value of the battery load, ω L represents the system operating angular frequency in the weak coupling mode, L p1 Represents the self-inductance of the first transmitting coil, L s Indicates the self-inductance of the receiving coil and stipulates that it has the following relationship with other coupling coefficients in the curve: In formula (10), β H represents the coupling change factor in the strong coupling mode, β L represents the coupling change factor in the weak coupling mode, k min Indicates the minimum working coupling coefficient, k exL represents the peak coupling coefficient in the weak coupling mode, k exH represents the peak coupling coefficient in the strong coupling mode, k max Indicates the maximum working coupling coefficient; The actual coupling change factor β o The definition is as follows: In formula (11), k max Indicates the maximum working coupling coefficient, k min Indicates the minimum working coupling coefficient and specifies the actual coupling change multiple β o It can be calculated by the following formula: β o ＝β H β L (12)， In formula (12), β H represents the coupling change factor in the strong coupling mode, β L Indicates the coupling change factor in the weakly coupled mode.

10. The method for designing parameters of a frequency-convertible reconfigurable wireless power transmission system according to claim 5, characterized in that: Step 6 specifically includes: The primary side series compensation capacitor C in the primary side compensation network p1 The calculation formula is as follows: The primary loop compensation capacitor C in the primary compensation network p2 The calculation formula is as follows: Primary branch compensation capacitor C in the primary compensation network x The calculation formula is as follows: The primary branch compensation inductor L in the primary compensation network x The calculation formula is as follows: Secondary side series compensation capacitor C in the secondary side compensation network s The value range of is as follows: The secondary loop compensation capacitor C in the secondary compensation network s1 The calculation formula is as follows: The secondary loop compensation inductor L in the secondary compensation network s1 The calculation formula is as follows: In formula (13) to formula (19), L eq Indicates the inductance value of the equivalent compensation inductance of the primary branch, L p1 Represents the self-inductance of the first transmitting coil, L p2 Represents the self-inductance of the second transmitting coil, L s Represents the self-inductance of the receiving coil, ω H represents the system operating angular frequency in the strong coupling mode, ω L represents the system operating angular frequency in the weakly coupled mode.

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