A parameter design method for wireless charging system with wide range of coupling coefficient variation

Abstract

The present invention discloses a method for designing parameters of a wireless charging system that is resistant to wide-range variations in coupling coefficients, comprising the following steps: first, setting system technical indicators based on the main circuit architecture of the wireless charging system and actual operating requirements; second, designing an initial system power-coupling curve and compensation component parameters based on the set technical indicators; and third, determining the coupling coefficient k. ps Is it within the initial coupling coefficient variation range? If so, the duty cycle is the initial duty cycle D0, and the process ends; if not, proceed to step 4; Step 4: Determine the coupling coefficient k ps Is it greater than the initial maximum coupling coefficient k max0 If so, first calculate the coupling coefficient k ps Determine the right range, determine the n value, and then design the corresponding nth duty cycle D on the right side Rn , end; if not, first calculate the coupling coefficient k ps Determine the left range, determine the n value, and then design the corresponding left nth duty cycle D Ln The present invention can ensure that the system output power fluctuates less when the coupling coefficient varies over a wide range.

Description

Technical Field

[0001] The present invention relates to a wireless charging system parameter design method, in particular to a wireless charging system parameter design method that is resistant to wide-range variation of coupling coefficient, and belongs 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 contactless energy transfer from a power source to a load. It offers safe, flexible, and reliable power supply and has been widely adopted in a variety of fields, including portable electronic devices, implantable medical devices, and underwater detectors. However, in practical applications, misalignment between the primary transmitting coil and the secondary receiving coil is inevitable, leading to drastic changes in the mutual inductance and coupling parameters between the coils, which in turn affects the stability of power transmission in IPT systems.

[0003] To this end, research teams at home and abroad have mainly started their research from the aspects of magnetic coupling mechanism design and compensation topology optimization. For example, the University of Hong Kong proposed a combination structure consisting of three layers of hexagonal coil arrays placed in an interlaced manner. By superimposing magnetic density, a uniform magnetic field is constructed, which effectively increases the coupling area. However, as a compromise, the consumables of the coils are increased, sacrificing the system transmission efficiency. Furthermore, some scholars have proposed a compensation topology optimization method. San Diego State University in the United States proposed a dual-coupled DLCC compensation topology, which effectively improves the system's anti-offset performance by coupling bilateral compensation inductors with energy coils. However, the proposed method is complex in design, and when the offset distance is long, the system output fluctuation is still large. In addition, the large number of compensation components, especially inductor coils, is not conducive to the compact design of the receiving side, resulting in an increase in system cost, volume and weight. Summary of the Invention

[0004] In order to overcome the defects and shortcomings of the prior art, the present invention further proposes a parameter design method for a wireless charging system that is resistant to wide-range variations in the coupling coefficient, which can ensure that the system output power fluctuates less when the coupling coefficient varies over a wide range.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A method for designing parameters of a wireless charging system with a wide range of anti-coupling coefficient variations, wherein the wireless charging system includes a DC voltage source U D , full-bridge inverter circuit, primary side resonant network, secondary side resonant network, rectifier filter circuit, DC-DC conversion circuit and battery equivalent load R o The two input terminals of the full-bridge inverter circuit are connected to the DC voltage source UD The two output ends of the full-bridge inverter circuit are connected to the two input ends of the primary resonant network in a one-to-one correspondence. The primary resonant network includes a primary first transmitting coil. L p1 , the primary side second transmitting coil L p2 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 and primary branch compensation components, the secondary side resonant network includes a secondary side receiving coil L s And the secondary side series compensation capacitor C s The primary resonant network and the secondary resonant network are coupled by mutual inductance, the two input ends of the rectifier filter circuit are connected one-to-one with the two output ends of the secondary resonant network, the two input ends of the direct-to-direct conversion circuit are connected one-to-one with the two output ends of the rectifier filter circuit, and the two input ends of the direct-to-direct conversion circuit are connected to the battery equivalent load. R o The method for designing parameters of a wireless charging system with a wide range of anti-coupling coefficient variations is implemented by the following steps:

[0007] S1: Setting the technical indicators of the wireless charging system, including: DC input voltage U D , preset output power P oset , battery equivalent load R o , system output power fluctuation ratio , system operating frequency , the first primary transmitting coil L p1 , the primary side second transmitting coil L p2 , secondary side receiving coil L s , initial extreme coupling coefficient k ex0 ;

[0008] S2: Based on the technical indicators set in S1, design the initial system power-coupling curve and the parameters of the compensation components in the wireless charging system. The parameters specifically include: coupling change multiple , initial minimum coupling coefficient k min0 , initial maximum coupling coefficient k max0 , primary side series compensation capacitor Cp1 , primary circuit compensation capacitor C p2 , primary branch compensation element impedance JX , secondary side series compensation capacitor C s ;

[0009] S3: Determine the coupling coefficient k ps Is it within the initial coupling coefficient variation range? If so, get the initial duty cycle D 0 and the initial equivalent AC load before the system rectifier and filter circuit R eq0 , end; if not, enter S4;

[0010] S4: Determine the coupling coefficient k ps Is it greater than the initial maximum coupling coefficient? k max0 If so, first calculate the coupling coefficient k ps Determine the right range and then design the corresponding nth duty cycle on the right side D Rn , get the nth equivalent AC load on the right side before the system rectifier and filter circuit R eqRn , the right side nth extreme coupling coefficient k exRn and the nth largest coupling coefficient on the right k maxRn , end; if not, first calculate the coupling coefficient k ps Make a left range determination and then design the corresponding left nth duty cycle D Ln , get the nth equivalent AC load on the left before the system rectifier and filter circuit R eqLn , the left nth extreme coupling coefficient k exLn , the nth minimum coupling coefficient on the left k minLn ,Finish.

[0011] Furthermore, the direct-to-direct conversion circuit is a buck-boost circuit.

[0012] Furthermore, the system output power fluctuation ratio in S1 is The definition of is as follows:

[0013]

[0014] in, Pomax and P omin The maximum and minimum values ​​of the power allowed to be transmitted by the wireless charging system are respectively provided, and they are stipulated to have the following relationship:

[0015]

[0016] Where, P oset is the preset output power.

[0017] Furthermore, the initial system power-coupling curve described in S2 The expression is as follows:

[0018]

[0019] Where: 、 ; is the system operating angular frequency, L p The first transmitting coil on the primary side L p1 Or the primary side second transmitting coil L p2 The self-inductance value of 、 L s is the self-inductance of the secondary receiving coil, U D is the voltage value of the DC voltage source, R o is the resistance value of the battery equivalent load, k p1s0 is the initial coupling coefficient between the first transmitting coil on the primary side and the receiving coil on the secondary side, k p2s0 is the initial coupling coefficient between the second transmitting coil on the primary side and the receiving coil on the secondary side, let ,and , k min0 is the initial minimum coupling coefficient, k max0 is the initial maximum coupling coefficient.

[0020] Furthermore, the primary branch compensation element is a primary branch compensation capacitor C x Or primary branch compensation inductance L x , the selection rules of its specific device characteristics are as follows:

[0021]

[0022] in,M p1s0 is the initial main coupling mutual inductance between the first transmitting coil on the primary side and the receiving coil on the secondary side, M p2s0 is the initial main coupling mutual inductance between the primary second transmitting coil and the secondary receiving coil, that is, 、 .

[0023] Furthermore, the coupling change factor described in S2 The expression is as follows:

[0024]

[0025] Furthermore, the initial minimum coupling coefficient in S2 k min0 and the initial maximum coupling coefficient k max0 The expression is as follows:

[0026]

[0027] Furthermore, the primary side series compensation capacitor in S2 C p1 , the primary circuit compensation capacitor C p2 , the impedance of the primary branch compensation element JX , the secondary side series compensation capacitor C s The expression is as follows:

[0028]

[0029] Furthermore, the initial duty cycle described in S3 D 0 is when the coupling coefficient k ps Greater than or equal to the initial minimum coupling coefficient k min0 , and is less than or equal to the initial maximum coupling coefficient k max0 When the DC-DC converter circuit controls the square wave duty cycle, the initial duty cycle is D 0 and the initial equivalent AC load before the system rectifier and filter circuit R eq0 The expression is as follows:

[0030]

[0031] Where: R o is the resistance value of the battery equivalent load.

[0032] Furthermore, the duty cycle of the right side n described in S4 D Rn When the coupling coefficient k ps Greater than the initial maximum coupling coefficient k max0 When the control square wave duty cycle of the DC-DC converter circuit is , where n is a positive integer, it must satisfy the range judgment formula on the right:

[0033]

[0034] in, The symbol indicates rounding up.

[0035] At this time, the right side nth duty cycle D Rn , the nth equivalent AC load on the right before the rectifier and filter circuit of the system R eqRn , the right side nth extreme coupling coefficient k exRn , the nth maximum coupling coefficient on the right side k maxRn The expression is as follows:

[0036] .

[0037] Furthermore, the left nth duty cycle described in S4 D Ln When the coupling coefficient k ps Less than the initial minimum coupling coefficient k min0 When , the control square wave duty cycle of the DC-DC converter circuit, where n is a positive integer, must satisfy the left range judgment formula:

[0038]

[0039] in, The symbol indicates rounding up.

[0040] At this time, the left nth duty cycle D Ln , the nth equivalent AC load on the left before the rectifier and filter circuit of the system R eqLn , the left side nth extreme coupling coefficient k exLn , the left nth minimum coupling coefficient k minLn The expression is as follows:

[0041] .

[0042] The beneficial effects of the present invention are:

[0043] 1. The present invention can change the equivalent AC load before the system rectifier and filter circuit by switching the duty cycle of the DC-DC conversion circuit at a fixed operating frequency, thereby connecting multiple coupling coefficient variation ranges in sequence to ensure that the system output power fluctuates less when the coupling coefficient varies over a wide range.

[0044] 2. The present invention provides a parameter design method for a wireless charging system that is resistant to wide-range variations in coupling coefficients. The method does not require any additional iterative or optimization algorithms, and can directly perform value assignment calculations, thereby enabling rapid determination of all system parameters and simplifying the system parameter design steps.

[0045] 3. The parameter design method for a wireless charging system with wide-range resistance to coupling coefficient changes provided by the present invention can be extended and applied to other low-order or high-order compensation topologies, that is, it is suitable for a class of compensation topologies with similar output characteristics, such as: primary-side detuned SS compensation topology and detuned LCC-S compensation topology. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 1. It is a flow chart of a method for designing parameters of a wireless charging system that is resistant to wide-range variation of coupling coefficients according to the present invention;

[0047] Figure 2 Schematic diagram of the main circuit architecture of the wireless charging system of the present invention;

[0048] Figure 3 This is a schematic diagram of the design of the curve of the output power of the system of the present invention changing with the coupling coefficient;

[0049] Figure 4 It is a theoretical calculation diagram of the curve of the output power of the system of the present invention changing with the coupling coefficient. DETAILED DESCRIPTION

[0050] Specific implementation method 1: Combination Figure 1-4 This embodiment describes a method for designing parameters of a wireless charging system that is resistant to wide-range variations in coupling coefficient.

[0051] The wireless charging system includes a DC voltage source U D , full-bridge inverter circuit, primary side resonant network, secondary side resonant network, rectifier filter circuit, DC-DC conversion circuit and battery equivalent load R o The two input terminals of the full-bridge inverter circuit are connected to the DC voltage source U DThe two output ends of the full-bridge inverter circuit are connected to the two input ends of the primary resonant network in a one-to-one correspondence. The primary resonant network includes a primary first transmitting coil. L p1 , the primary side second transmitting coil L p2 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 and a primary branch compensation element, preferably, the primary branch compensation element is a primary branch compensation capacitor C x Or primary branch compensation inductance L x The secondary side resonant network includes a secondary side receiving coil L s And the secondary side series compensation capacitor C s The primary resonant network and the secondary resonant network are coupled by mutual inductance, the two input ends of the rectifier filter circuit are connected one-to-one with the two output ends of the secondary resonant network, the two input ends of the direct-to-direct conversion circuit are connected one-to-one with the two output ends of the rectifier filter circuit, and the two input ends of the direct-to-direct conversion circuit are connected to the battery equivalent load. R o Preferably, the DC-DC conversion circuit is a buck-boost circuit (Buck-Boost circuit), which can be used in the full coupling coefficient variation range with the parameter design method, that is, the coupling coefficient k ps Between 0 and 1, the system can achieve constant power output characteristics against coupling coefficient changes.

[0052] Specific examples Figure 2 As shown, the main circuit architecture of the wireless charging system specifically includes: a full-bridge inverter circuit, a primary-side resonant network, a secondary-side resonant network, a rectifier and filter circuit, and a direct-to-direct conversion circuit; the primary-side resonant network is composed of the primary first transmitting coil L p1 , the primary side second transmitting coil L p2 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , the primary branch compensation element is composed of the primary branch compensation element can be the primary branch compensation capacitor C x Or the primary branch compensation inductor L xThe two output terminals of the full-bridge inverter circuit are connected to the two input terminals of the primary resonant network in a one-to-one correspondence, and the two input terminals are connected to the DC voltage source. U D The secondary side resonant network is connected to the secondary side receiving coil L s , secondary side series compensation capacitor C s The two input terminals of the rectifier filter circuit are connected to the two output terminals of the secondary resonant network in a one-to-one correspondence; the DC-DC conversion circuit is a Buck-Boost circuit, the two input terminals of which are connected to the two output terminals of the rectifier filter circuit in a one-to-one correspondence, and the two input terminals of which are connected to the battery equivalent load R o connected.

[0053] like Figure 1 As shown, the parameter design method of a wireless charging system with a wide range of anti-coupling coefficient variations is achieved by the following steps:

[0054] S1: According to the main circuit structure of the wireless charging system and the actual working conditions, set the technical indicators of the wireless charging system. The technical indicators specifically include: DC input voltage U D , preset output power P oset , battery equivalent load R o , system output power fluctuation ratio , system operating frequency , the first primary transmitting coil L p1 , the primary side second transmitting coil L p2 , secondary side receiving coil L s and the initial extreme coupling coefficient k ex0 .

[0055] The system output power fluctuation ratio The definition of is:

[0056] (1)

[0057] in, P omax and P omin The maximum and minimum values ​​of the power allowed to be transmitted by the wireless charging system are respectively provided, and they are stipulated to have the following relationship:

[0058] (2)

[0059] Where: P oset is the preset output power.

[0060] S2: Based on the technical indicators set in S1, design the initial system power-coupling curve and the parameters of the compensation components in the wireless charging system. The parameters specifically include: coupling change multiple , initial minimum coupling coefficient k min0 , initial maximum coupling coefficient k max0 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , primary branch compensation element impedance JX And the secondary side series compensation capacitor C s .

[0061] like Figure 3 As shown, the initial system power-coupling curve , where the system output power P o With the initial coupling coefficient k ps0 Decrease, its value first increases and then decreases, the specific expression is:

[0062] (3)

[0063] Where: 、 ; is the system operating angular frequency; L p The first transmitting coil on the primary side L p1 Or the primary side second transmitting coil L p2 The self-inductance value of 、 L s is the self-inductance of the secondary receiving coil; U D is the voltage value of the DC voltage source; R o is the resistance value of the battery equivalent load; k p1s0 is the initial coupling coefficient between the first transmitting coil on the primary side and the receiving coil on the secondary side, k p2s0 is the initial coupling coefficient between the second transmitting coil on the primary side and the receiving coil on the secondary side, let ,and , kmin0 is the initial minimum coupling coefficient, k max0 is the initial maximum coupling coefficient; JX is the impedance of the primary branch compensation element, and:

[0064] (4)

[0065] in, L x Compensation inductance for the primary branch, C x is the primary branch compensation capacitor, M p1s0 is the initial main coupling mutual inductance between the first transmitting coil on the primary side and the receiving coil on the secondary side, M p2s0 is the initial main coupling mutual inductance between the primary second transmitting coil and the secondary receiving coil, that is, 、 .

[0066] The coupling change factor It can be calculated by the following formula:

[0067] (5)

[0068] in, is the system output power fluctuation ratio.

[0069] The initial minimum coupling coefficient k min0 , initial maximum coupling coefficient k max0 Respectively expressed as:

[0070] (6)

[0071] in, k ex0 is the initial extreme coupling coefficient.

[0072] The primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , primary branch compensation element impedance JX , secondary side series compensation capacitor C s Respectively expressed as:

[0073] (7)

[0074] S3: Determine the coupling coefficient k psIs it within the initial coupling coefficient variation range? If so, get the initial duty cycle D 0 and the initial equivalent AC load before the system rectifier and filter circuit R eq0 , end; if not, enter S4.

[0075] like Figure 3 As shown, when the coupling coefficient k ps In the initial coupling coefficient variation range The internal coupling coefficient k ps Greater than or equal to the initial minimum coupling coefficient k min0 , and is less than or equal to the initial maximum coupling coefficient k max0 When the DC-DC converter circuit controls the square wave duty cycle D Initial duty cycle D 0; at this time (coupling coefficient k ps Greater than or equal to the initial minimum coupling coefficient k min0 , and is less than or equal to the initial maximum coupling coefficient k max0 Initial duty cycle D 0. Initial equivalent AC load before the system rectifier and filter circuit R eq0 Respectively expressed as:

[0076] (8)

[0077] Where: R o is the resistance value of the battery equivalent load.

[0078] S4: Determine the coupling coefficient k ps Is it greater than the initial maximum coupling coefficient? k max0 If so, first calculate the coupling coefficient k ps Determine the right range and then design the corresponding nth duty cycle on the right side D Rn , get the nth equivalent AC load on the right side before the system rectifier and filter circuit R eqRn , the right side nth extreme coupling coefficient k exRn and the nth largest coupling coefficient on the right k maxRn , end; if not, first calculate the coupling coefficient kps Make a left range determination and then design the corresponding left nth duty cycle D Ln , get the nth equivalent AC load on the left before the system rectifier and filter circuit R eqLn , the left nth extreme coupling coefficient k exLn , the nth minimum coupling coefficient on the left k minLn ,Finish.

[0079] like Figure 3 As shown, when the coupling coefficient k ps In the initial coupling coefficient variation range When the coupling coefficient k ps Greater than the initial maximum coupling coefficient k max0 When the DC-DC converter circuit controls the square wave duty cycle D It is called the nth duty cycle on the right D Rn , where n must satisfy the right range judgment formula:

[0080] (9)

[0081] At this time (coupling coefficient k ps Greater than the initial maximum coupling coefficient k max0 When) the nth duty cycle on the right D Rn , the nth equivalent AC load on the right before the system rectifier and filter circuit R eqRn , the right side nth extreme coupling coefficient k exRn , the nth largest coupling coefficient on the right k maxRn Respectively expressed as:

[0082] (10)

[0083] like Figure 3 As shown, when the coupling coefficient k ps In the initial coupling coefficient variation range On the left side, the coupling coefficient k ps Less than the initial minimum coupling coefficient k min0 When the DC-DC converter circuit controls the square wave duty cycle D It is called the left nth duty cycle DLn , where n must satisfy the left range judgment formula:

[0084] (11)

[0085] At this time (coupling coefficient k ps Less than the initial minimum coupling coefficient k min0 ) Left side nth duty cycle D Ln , the nth equivalent AC load on the left before the system rectifier and filter circuit R eqLn , the left nth extreme coupling coefficient k exLn , the nth minimum coupling coefficient on the left k minLn Respectively expressed as:

[0086] (12)

[0087] in, The symbol indicates rounding up, for example: 、 ; n is a positive integer, i.e. 1, 2, 3...; is the coupling change multiple; R eq0 is the initial equivalent AC load before the system rectifier and filter circuit; k ex0 is the initial extreme coupling coefficient.

[0088] Specifically, to verify the correctness and feasibility of the parameter design method for a wireless charging system with a wide range of anti-coupling coefficient variations, a detailed parameter design process is given below in conjunction with a design example:

[0089] First, the system technical indicators are given, as shown in Table 1:

[0090] Table 1 System technical indicators

[0091]

[0092] Then, according to the technical indicators shown in Table 1, the initial system power-coupling curve and compensation component parameters are designed. Specifically including: coupling change multiple , initial minimum coupling coefficient k min0 , initial maximum coupling coefficient k max0 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor Cp2 , primary branch compensation element impedance JX (Here the primary branch compensation inductance L x For example), the secondary side series compensation capacitor C s , as shown in Table 2:

[0093] Table 2 Initial system power-coupling curve and compensation component parameters

[0094]

[0095] Then, when the coupling coefficient k ps In the initial coupling coefficient variation range The internal coupling coefficient k ps Greater than or equal to the initial minimum coupling coefficient k min0 , and is less than or equal to the initial maximum coupling coefficient k max0 At this time, the initial duty cycle D 0. Initial equivalent AC load before the system rectifier and filter circuit R eq0 Respectively expressed as:

[0096] (13)

[0097] Furthermore, in order to more intuitively demonstrate that the present invention has the ability to output constant power against wide-range variations in coupling coefficient, when the coupling coefficient k ps In the initial coupling coefficient variation range When the right side or left side is , n is 1 and 2 respectively. Therefore, the first duty cycle on the right side can be obtained by equation (10) and equation (12) respectively. D R1 , the first equivalent AC load on the right before the system rectifier and filter circuit R eqR1 , the first extreme coupling coefficient on the right k exR1 , the first maximum coupling coefficient on the right k maxR1 ; The second duty cycle on the right D R2 , the second equivalent AC load on the right before the system rectifier and filter circuit R eqR2 , the second extreme coupling coefficient on the right k exR2 , the second largest coupling coefficient on the right k maxR2 ; Left first duty cycleD L1 , the first equivalent AC load on the left before the system rectifier and filter circuit R eqL1 , the first extreme coupling coefficient on the left k exL1 , the first minimum coupling coefficient on the left k minL1 ; The second duty cycle on the left D L2 , the second equivalent AC load on the left before the system rectifier and filter circuit R eqL2 , the second extreme coupling coefficient on the left k exL2 , the second minimum coupling coefficient on the left k minL2 , as shown in Table 3:

[0098] Table 3 Summary of all parameters

[0099]

[0100] Finally, based on the initial system power-coupling curve The expression (3) is obtained by using Mathematica mathematical analysis software. Figure 4 The system output power shown P o With coupling coefficient k ps Theoretical calculation diagram of the change curve. Figure 3 and Figure 4 It can be seen that in order to meet the system output power fluctuation ratio The technical indicator requirement is 5%. When the duty cycle of the control square wave of the DC-DC converter circuit is D The second duty cycle on the left D L2 When the coupling coefficient k ps It can be changed between 0.0962 and 0.1516; when the duty cycle of the control square wave of the DC-DC converter circuit is D The first duty cycle on the left D L1 When the coupling coefficient k ps It can be changed between 0.1516 and 0.2390; when the duty cycle of the control square wave of the DC-DC converter circuit is D is the initial duty cycle D 0, the coupling coefficient k ps It can be changed between 0.2390 and 0.3766; when the duty cycle of the control square wave of the DC-DC converter circuit is D The first duty cycle on the rightD R1 When the coupling coefficient k ps It can be changed between 0.3766 and 0.5936; when the duty cycle of the control square wave of the DC-DC converter circuit is D The second duty cycle on the right D R2 When the coupling coefficient k ps It can vary between 0.5936 and 0.9355, that is, 5 different coupling coefficient variation ranges are connected in sequence.

[0101] In summary, when the control square wave duty cycle of the DC-DC converter circuit is D In accordance with the designed D R1 、 D R2 、 D 0. D L1 、 D L2 When switching between k ps The coupling coefficient can vary between 0.0962 and 0.9355, meaning it varies nearly 10-fold. The system output power ranges from 904.76 W to 1000 W, and the system output power fluctuation remains within 5% of the set value. Therefore, the present invention has the ability to maintain constant power output despite wide variations in the coupling coefficient, ensuring minimal fluctuations in the system output power over this wide range.

[0102] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as a preferred embodiment as above, it is not intended to limit the present invention. Any technician familiar with the present profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical content disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent replacement and improvement of the above embodiments made according to the technical essence of the present invention, within the spirit and principles of the present invention, without departing from the content of the technical solution of the present invention, shall still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A method for designing wireless charging system parameters to resist wide-range variations in coupling coefficient, characterized by: The wireless charging system includes a DC voltage source U D , full-bridge inverter circuit, primary side resonant network, secondary side resonant network, rectifier filter circuit, DC-DC conversion circuit and battery equivalent load R o The two input terminals of the full-bridge inverter circuit are connected to the DC voltage source U D The two output terminals of the full-bridge inverter circuit are connected to the two input terminals of the primary resonant network in a one-to-one correspondence. The primary resonant network includes a primary first transmitting coil L p1 , the primary side second transmitting coil L p2 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 and primary branch compensation components, the secondary resonant network includes a secondary receiving coil L s And the secondary side series compensation capacitor C s The primary resonant network and the secondary resonant network are coupled by mutual inductance. The two input terminals of the rectifier filter circuit are connected to the two output terminals of the secondary resonant network in a one-to-one correspondence. The two input terminals of the direct-to-direct conversion circuit are connected to the two output terminals of the rectifier filter circuit in a one-to-one correspondence. The two input terminals of the direct-to-direct conversion circuit are connected to the battery equivalent load R o The method for designing parameters of a wireless charging system with a wide range of anti-coupling coefficient variations is implemented by the following steps: S1: Setting the technical indicators of the wireless charging system, which specifically include: DC input voltage U D , preset output power P oset , battery equivalent load R o , system output power fluctuation ratio δ, system operating frequency f, primary side first transmitting coil L p1 , the primary side second transmitting coil L p2 , secondary side receiving coil L s and the initial extreme coupling coefficient k ex0 ; S2: Based on the technical indicators set in S1, design the initial system power-coupling curve and the parameters of the compensation components in the wireless charging system. The parameters specifically include: coupling change multiple β, initial minimum coupling coefficient k min0 , initial maximum coupling coefficient k max0 , primary side series compensation capacitor C p1 , primary circuit compensation capacitor C p2 , the primary branch compensation element impedance jX and the secondary side series compensation capacitor C s ; S3: Determine the coupling coefficient k ps Is it within the initial coupling coefficient variation range [k min0 , k max0 If so, obtain the initial duty cycle D0 and the initial equivalent AC load R before the system rectifier filter circuit. eq0 , end; if not, enter S4; S4: Determine the coupling coefficient k ps Is it greater than the initial maximum coupling coefficient k max0 If so, first calculate the coupling coefficient k ps Determine the right range and then design the corresponding right nth duty cycle D Rn , obtain the nth equivalent AC load R on the right side before the system rectifier and filter circuit eqRn , the right side nth extreme coupling coefficient k exRn and the nth largest coupling coefficient k on the right maxRn , end; if not, first calculate the coupling coefficient k ps Make a left range determination and then design the corresponding left nth duty cycle D Ln , obtain the nth equivalent AC load R on the left before the system rectifier and filter circuit eqLn , the left nth extreme coupling coefficient k exLn , the nth minimum coupling coefficient k on the left minLn ,Finish.

2. The method for designing wireless charging system parameters to resist wide-range variation of coupling coefficient according to claim 1, characterized in that: The definition of the system output power fluctuation ratio δ in S1 is as follows: Among them, P omax and P omin The maximum and minimum values ​​of the power allowed to be transmitted by the wireless charging system are respectively provided, and they are stipulated to have the following relationship: Where, P oset is the preset output power.

3. The method for designing wireless charging system parameters with wide-range anti-coupling coefficient variation according to claim 2, characterized in that: The initial system power-coupling curve P described in S2 o (k ps0 )The expression is as follows: Where: ω is the system operating angular frequency, L p The first transmitting coil L on the primary side p1 Or the primary side second transmitting coil L p2 The self-inductance value, let L p =L p1 =L p2 , L s is the self-inductance of the secondary receiving coil, U D is the voltage value of the DC voltage source, R o is the resistance value of the battery equivalent load, k p1s0 is the initial coupling coefficient between the first transmitting coil on the primary side and the receiving coil on the secondary side, k p2s0 is the initial coupling coefficient between the second transmitting coil on the primary side and the receiving coil on the secondary side, let k ps0 =k p1s0 =k p2s0 , and k ps0 ∈[k min0 , k max0 ], k min0 is the initial minimum coupling coefficient, k max0 is the initial maximum coupling coefficient.

4. The method for designing wireless charging system parameters to resist wide-range variation of coupling coefficient according to claim 3, characterized in that: The primary branch compensation element is the primary branch compensation capacitor C x Or the primary branch compensation inductor L x , the selection rules of its specific device characteristics are as follows: Among them, M p1s0 is the initial main coupling mutual inductance between the first transmitting coil on the primary side and the receiving coil on the secondary side, M p2s0 is the initial main coupling mutual inductance between the primary second transmitting coil and the secondary receiving coil, that is, 5. The method for designing wireless charging system parameters with resistance to wide-range variation of coupling coefficient according to claim 3, characterized in that: The expression of the coupling change factor β described in S2 is as follows:

6. The method for designing wireless charging system parameters to resist wide-range variation of coupling coefficient according to claim 5, characterized in that: The initial minimum coupling coefficient k described in S2 min0 and the initial maximum coupling coefficient k max0 The expression is as follows:

7. The method for designing wireless charging system parameters with resistance to wide-range variation of coupling coefficient according to claim 3, characterized in that: The primary side series compensation capacitor C p1 , the primary circuit compensation capacitor C p2 , the primary branch compensation element impedance jX, the secondary side series compensation capacitor C s The expression is as follows: Where X is the imaginary part of the impedance of the primary branch compensation element, that is, 8. The method for designing wireless charging system parameters to resist wide-range variation of coupling coefficient according to claim 1, characterized in that: The initial duty cycle D0 in S3 is when the coupling coefficient k ps Greater than or equal to the initial minimum coupling coefficient k min0 , and is less than or equal to the initial maximum coupling coefficient k max0 When the control square wave duty cycle of the DC-DC conversion circuit is 1, the initial duty cycle D0 and the initial equivalent AC load R before the system rectifier filter circuit are equal. eq0 The expression is as follows: Where: R o is the resistance value of the battery equivalent load.

9. The method for designing wireless charging system parameters to resist wide-range variation of coupling coefficient according to claim 1, characterized in that: The right n-th duty cycle D described in S4 Rn When the coupling coefficient k ps Greater than the initial maximum coupling coefficient k max0 When the control square wave duty cycle of the DC-DC converter circuit is , where n is a positive integer, it must satisfy the range judgment formula on the right: in, The symbol indicates rounding up. At this time, the right nth duty cycle D Rn , the nth equivalent AC load R on the right before the system rectifier and filter circuit eqRn , the right side nth extreme value coupling coefficient k exRn , the right side nth maximum coupling coefficient k maxRn The expression is as follows:

10. The method for designing parameters of a wireless charging system with resistance to wide-range variation of coupling coefficient according to claim 1, characterized in that: The left nth duty ratio D described in S4 Ln When the coupling coefficient k ps Less than the initial minimum coupling coefficient k min0 When , the control square wave duty cycle of the DC-DC converter circuit, where n is a positive integer, must satisfy the left range judgment formula: in, The symbol indicates rounding up. At this time, the left nth duty cycle D Ln , the nth equivalent AC load R on the left before the system rectifier filter circuit eqLn , the left side nth extreme value coupling coefficient k exLn , the left nth minimum coupling coefficient k minLn The expression is as follows:

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