Method for calculating parasitic capacitance of winding of electromagnetic conversion equipment

Abstract

The invention discloses a method for calculating winding stray capacitance of electromagnetic conversion equipment. The method comprises the following steps: S1, establishing a multi-layer winding stray capacitance analytical model considering a turn-to-turn distance; s2, the winding disorder degree is defined, the possible distribution position of each turn of coil in the winding is obtained, and an analytical expression of turn-to-turn capacitance and interlayer capacitance related to the winding disorder degree is deduced; s3, according to the multi-layer winding stray capacitance analytical model, obtaining a calculation formula of the total stray capacitance of the winding; s4, obtaining a probability model of winding coil distribution according to the possible distribution position of each turn of coil, and then calculating all possible distribution winding parasitic capacitance values; and S5, according to the calculation result of the parasitic capacitance of the winding, drawing a distribution probability histogram of all possible parasitic capacitance values of the winding when the winding disorder degree is D, and predicting the total parasitic capacitance value of the winding. The method is suitable for stray capacitance calculation of electromagnetic conversion equipment with various enameled wire shapes, and the calculation result is closer to the actual value.

Description

Technical Field

[0001] The present invention relates to the technical field of electromagnetic conversion equipment modeling, and in particular to a method for calculating the parasitic capacitance of a winding of an electromagnetic conversion equipment. Background Art

[0002] As the operating frequency of wide bandgap power devices increases, the parasitic parameters of the circuit system at high switching speeds will cause oscillations in the voltage and current waveforms, increase the loss of the switching process, and limit the increase in the operating frequency of the circuit system. One of the main reasons for the above problems is the parasitic capacitance of the circuit. For electromagnetic conversion equipment such as inductors, transformers, and motors, the presence of parasitic capacitance in the high-frequency range will significantly change its impedance. The parasitic capacitance generated by the motor winding as a load in the circuit loop has an even more obvious impact. The parasitic capacitance of the winding is mainly caused by the following two reasons: the insulating medium between the windings and the dielectric between the windings and the surrounding environment. Therefore, in equipment such as motors, transformers, and inductors, there is a certain capacitance between the windings and between the windings and the external environment.

[0003] The traditional calculation of parasitic capacitance assumes that the coil distribution of the winding is ideal, and that the spacing between each turn of the coil is equal and evenly distributed. In the actual winding process, due to the existence of spindle errors, manual winding or machine winding cannot guarantee that the winding is evenly distributed.

[0004] At present, the calculation method for the parasitic capacitance of the coil winding is to use an ideal distribution model, and the calculated parasitic capacitance value often has a large error with the actual measured value. Summary of the invention

[0005] Purpose of the invention: The purpose of the present invention is to provide a method for calculating the parasitic capacitance of the winding of electromagnetic conversion equipment. According to the actual situation of coil distribution, a probability model of the distribution of unevenly distributed winding coils is adopted to make the calculation result closer to the actual value.

[0006] Technical solution: A method for calculating the parasitic capacitance of the winding of an electromagnetic conversion equipment, comprising the following steps:

[0007] S1, establish an analytical model of multi-layer winding parasitic capacitance considering the turn-to-turn distance, and divide the distributed capacitance into turn-to-turn capacitance and layer-to-layer capacitance;

[0008] S2, define the winding disorder, obtain the possible distribution position of each turn of the coil in the winding, and derive the analytical expressions of the inter-turn capacitance and inter-layer capacitance related to the winding disorder;

[0009] S3, according to the parasitic capacitance analytical model of multi-layer windings, the calculation formula of the total parasitic capacitance of the windings is obtained;

[0010] S4, and derive a probability model of the winding coil distribution according to the possible distribution position of each turn of the coil; and calculate all possible distribution values ​​of the winding parasitic capacitance according to the probability model of the winding coil distribution;

[0011] S5, based on the calculation result of the winding parasitic capacitance, draw a distribution probability histogram of all possible parasitic capacitance values ​​of the winding when the winding disorder degree is D, where the value with the highest probability of occurrence is the predicted value of the total parasitic capacitance of the winding.

[0012] Furthermore, the capacitance formed between adjacent conductor turns in the same layer is the inter-turn capacitance; the capacitance formed between adjacent conductor turns in the same position in each layer is the inter-layer capacitance.

[0013] Further, in step S2, when the cross section of the winding conductor is circular, the turn-to-turn capacitance C of the i-th winding layer is tti The expression is:

[0014]

[0015] In the formula, ε r is the relative dielectric constant of the wire insulation layer, ε0 is the vacuum dielectric constant, d tt is the distance between adjacent turns of conductor, D c D is the diameter of the copper core inside the conductor. o is the outer diameter of the wire; θ is the integral angle, the integral angle is from θ1 to θ2; l ti is the circumference of the i-th winding;

[0016] When the cross section of the winding conductor is rectangular, the inter-turn capacitance C′ of the i-th winding layer is tti The expression is:

[0017]

[0018] Among them, d is the internal copper core width of the conductor, D′ is the outer layer width of the conductor, and d tt is the distance between turns of the conductor; h is the width of the insulation layer of the conductor.

[0019] Furthermore, the winding disorder degree is the maximum distance between the center of the kth coil and the center of the k+1th coil, denoted as D, and the distance between the center of the kth coil and the center of the k+1th coil is any value between 2r and D, where r is the radius of the circular wire or half the width of the flat wire; assuming that the error is uniformly distributed, the probability of the k+1th coil appearing at all positions in the interval (2r, D) is equal;

[0020] If the first turn of the winding is placed at a given position, then there are m2 positions for the second turn within D, and m positions for the kth turn. k positions; let the number of possible positions of the next turn in D be m i, then the distribution of all n-turn windings is m i n .

[0021] Further, in step S4, the implementation steps of calculating all possible parasitic capacitance values ​​of the winding are as follows:

[0022] S41, place the first turn at the specified position and set the number of possible positions m for the next turn i The same operation is performed on the other turns to obtain a winding distribution;

[0023] S42, determining the adjacency mode between adjacent turns and the corresponding integral angle according to the distribution of the winding;

[0024] S43, when the disorder degree is D, all possible distributed parasitic capacitance values ​​of the same winding are calculated according to the energy method;

[0025] S44, repeating steps S41 to S43 to obtain parasitic capacitance values ​​in all distribution situations in the winding.

[0026] Compared with the prior art, the present invention has the following significant effects:

[0027] 1. The uneven winding coil distribution model proposed in the present invention is applicable to the parasitic capacitance calculation of electromagnetic conversion equipment with various enameled wire shapes (round wire, flat wire or square wire, etc.);

[0028] 2. The present invention proposes a method for reducing the number of samples of uneven distribution, which reduces the number of samples of all uneven distribution situations by limiting the possible positions of coil distribution, and uses the KS test to prove the accuracy of this method, thereby reducing the amount of calculation of uneven distribution of windings;

[0029] 3. According to the actual situation of coil distribution, the present invention proposes a probability model for the distribution of unevenly distributed winding coils, so that the calculation results are closer to the actual values ​​and are more meaningful for the practical application of electromagnetic conversion equipment in engineering. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is the overall flow chart of the present invention;

[0031] Figure 2 It is a cross-sectional diagram of a round wire multilayer winding under ideal distribution;

[0032] Figure 3 It is a cross-sectional diagram of a flat wire multilayer winding under ideal distribution;

[0033] Figure 4 It is a schematic diagram of the analytical model of the inter-turn capacitance of a circular wire;

[0034] Figure 5It is a differential schematic diagram of the analytical model of the capacitance between turns of a circular wire;

[0035] Figure 6 Schematic diagram of the adjacent pattern of the arrangement of the turns of a circular wire, where (a), (b), and (c) are adjacent patterns when the winding coils are closely arranged, and (d), (e), and (f) are adjacent patterns when the winding coils are spaced apart;

[0036] Figure 7 It is a schematic diagram of the analytical model of the inter-turn capacitance of flat wire;

[0037] Figure 8 It is a schematic diagram of uneven distribution of windings;

[0038] Fig. 9 It is a schematic diagram of the ideal uniform distribution of circular lines;

[0039] Fig.10 This is a schematic diagram of the ideal uniform distribution of flat wires;

[0040] Fig.11 It is a schematic diagram of the definition of disorder of circular line;

[0041] Fig.12 It is a schematic diagram of the definition of disorder of flat wire;

[0042] Fig.13 It is a schematic diagram of winding distribution when the disorder degree is different;

[0043] Fig.14 It is a schematic diagram of possible positions of windings with uneven distribution of round wires;

[0044] Fig.15 It is a schematic diagram of possible positions of unevenly distributed windings of flat wires;

[0045] Fig.16 is the probability distribution histogram of parasitic capacitance values ​​of large samples and small samples;

[0046] Fig.17 It is the distribution probability histogram of all the distributed parasitic capacitance values ​​of the winding. DETAILED DESCRIPTION

[0047] The present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods.

[0048] The present invention provides a method for calculating the parasitic capacitance of the winding of an electromagnetic conversion equipment taking into account the influence of the uneven arrangement of the coils. The flow chart is as follows: Figure 1 As shown, the steps include:

[0049] Step 1, establishing an analytical model of multi-layer winding parasitic capacitance considering the turn-to-turn distance;

[0050] like Figure 2The figure shows a cross-sectional diagram of a round wire multilayer winding under an ideal distribution.

[0051] like Figure 3 The figure shows a cross-sectional diagram of a flat wire multilayer winding under ideal distribution. The distributed capacitance is divided into two categories: inter-turn capacitance and inter-layer capacitance. The capacitance formed between adjacent conductor turns in the same layer is the inter-turn capacitance, and the capacitance formed between adjacent conductor turns in the same position in each layer is the inter-layer capacitance. The iron core and the enameled wire are isolated by insulating paper.

[0052] Step 2, according to the analytical model of multi-layer winding parasitic capacitance, derive the analytical expressions of inter-turn capacitance and inter-layer capacitance, and obtain the calculation formula of the total parasitic capacitance of the winding;

[0053] like Figure 4 The figure shows the schematic diagram of the analytical model of the inter-turn capacitance of a circular wire. tt An air gap capacitor C ttg and two insulating layer capacitors C ttc Composition; D c D is the diameter of the copper core inside the conductor. o is the outer diameter of the wire, and θ is the integral angle. The inter-turn parasitic capacitance C is derived by analytical method. tt .

[0054] like Figure 5 As shown in the figure, since the cross section of the winding wire is circular, the capacitance solution path changes with θ. With θ as the unit, the inter-turn capacitance is solved by calculus. The differential of the conductor circular path, r is the radius of the conductor circular path. The air gap capacitance C ttg The differential expression of is:

[0055]

[0056] Where ε0 is the dielectric constant of vacuum, l t is the circumference of the conductor loop, D o is the outer diameter of the wire; x(θ) is the air gap path length;

[0057] The air gap path length x(θ) is:

[0058] x(θ)=D o (1-cosθ)+d tt (2)

[0059] Where D o is the outer diameter of the wire, d tt is the turn-to-turn distance;

[0060] Insulation layer capacitance C ttc The differential expression of is:

[0061]

[0062] In the formula, ε r is the relative dielectric constant of the wire insulation layer, ε0 is the vacuum dielectric constant, l t is the circumference of the conductor loop, D o is the outer diameter of the wire, D c is the diameter of the copper core inside the conductor;

[0063] Therefore, the equivalent inter-turn capacitance differential is obtained:

[0064]

[0065] Integrating equation (4) yields the turn-to-turn capacitance C tt , let the integration angle be from θ1 to θ2.

[0066] Therefore, considering d tt The inter-turn capacitance C of the i-th layer winding tti for:

[0067]

[0068] In the formula, ε r is the relative dielectric constant of the wire insulation layer, ε0 is the vacuum dielectric constant, d tt is the distance between adjacent turns of conductor, and the conductor D c D is the diameter of the copper core inside the conductor. o is the outer diameter of the wire, θ is the integral angle, l ti is the circumference of the i-th winding.

[0069] Calculation of interlayer capacitance considering interlayer distance, C ll The structure of C tt The same, so its calculation formula is the same as the turn-to-turn capacitance C tt It can be seen from the calculation formula that the calculated value of the capacitance is related to the value of the integral angle θ, and the integral angle is related to the distribution of the round wire winding coil.

[0070] like Figure 6 As shown in the figure, it is a schematic diagram of the adjacency mode of the turn arrangement of circular wire; there are six adjacency modes for the turn arrangement, such as Figure 6 As shown in (a)-(f) of the figure, the variables of the six modes are the values ​​of the integral angle θ. It can be found that when the distance d changes, it is equivalent to changing the values ​​of θ1 and θ2 in formula (5). Therefore, when calculating the total parasitic capacitance of the winding, only the integral angle of the adjacent winding needs to be considered.

[0071] like Figure 7 The figure shows the schematic diagram of the analytical model of the inter-turn capacitance of a flat wire (i.e., the cross section of the wire is rectangular); among them, the inter-turn capacitance C′ tt By an air gap capacitor C' ttgand two insulating layer capacitances C′ ttc Composition; d is the internal copper core width of the conductor, D′ is the outer layer width of the conductor, and the inter-turn parasitic capacitance C is derived by analytical method. tt , the specific calculation process includes:

[0072] Air gap capacitance C' ttg The expression is:

[0073]

[0074] Where ε0 is the dielectric constant of vacuum, l t is the circumference of the conductor loop, D′ is the outer width of the conductor, d tt is the distance between turns of the conductor;

[0075] Insulation layer capacitance C′ ttc The expression is:

[0076]

[0077] In the formula, ε r is the relative dielectric constant of the wire insulation layer, l t is the circumference of the conductor loop path, d is the width of the copper core inside the conductor, and h is the width of the conductor insulation layer;

[0078] Therefore, the equivalent inter-turn capacitance expression is obtained:

[0079]

[0080] Calculation of interlayer capacitance considering interlayer distance, C ll The structure of C tt The same, so its calculation formula is the same as the turn-to-turn capacitance C tt Consistent.

[0081] Total parasitic capacitance of winding C p It can be obtained by the node voltage method or the energy method. Taking the energy method as an example, the energy method assumes that the voltage of the winding coil increases linearly from the first turn to the last turn. The voltage difference between adjacent turns is considered to be constant within a specific turn. Assuming that a voltage V is applied to the two terminals of the winding, the expressions for the voltage V(k) of the kth turn and the total electrical energy E stored between the turns are as follows:

[0082]

[0083] C ij Calculated from the inter-turn capacitance and inter-layer capacitance.

[0084] The total parasitic capacitance of the winding is C p The calculation formula is:

[0085]

[0086] Among them, i and j are the turn numbers, i is the previous turn, j is the next turn; V ij Represents the voltage between the i-th turn and the j-th turn; n is the total number of turns in the winding.

[0087] Step 3, defining the winding disorder degree, obtaining the possible distribution position of each coil turn in the winding, and obtaining the probability model of the winding coil distribution according to the possible distribution position of each coil turn;

[0088] The ideal winding arrangement is that the k+1th turn and the kth turn are closely arranged. If r is defined as the outer radius of the wire cross section, the distance between the center of the kth turn coil and the center of the k+1th turn coil is exactly 2r, and the coil is ideally distributed at this time.

[0089] In actual situations, the position deviation between the actual rotation axis of the winding spindle and its ideal rotation axis leads to uneven distribution of the coils of the winding.

[0090] like Figure 8 The figure shows the uneven distribution of windings. Due to the unequal distance between turns, each turn of the coil is not evenly distributed. This is usually caused by the winding operator or the winding machine's winding spindle error. The winding spindle error mainly refers to the spindle rotation error, which is the position deviation between the actual spindle rotation axis and its ideal rotation axis.

[0091] like Fig. 9 As shown in the figure, it is a schematic diagram of the ideal uniform distribution of circular wire. The distance between the center of each turn of the coil and the center of the next turn of the coil is exactly 2r, and the coil at this time is ideally evenly distributed; Fig.10 Shown is a schematic diagram of ideal uniform distribution of flat wires.

[0092] like Fig.11 As shown in the figure, it is a schematic diagram of the definition of circular wire disorder. Among them, disorder is the maximum distance between the center of the kth turn coil and the center of the (k+1)th turn coil, denoted as D1. The distance between the center of the kth turn coil and the center of the (k+1)th turn coil can be any value between 2r and D1. If it is assumed that the error is uniformly distributed, the probability of the (k+1)th turn coil appearing at all positions in the interval (2r, D1) is equal. By defining the disorder of the winding, the arrangement of the uneven winding can be determined, that is, each turn is evenly placed within the distance (2r, D1) from the previous turn.

[0093] like Fig.12The figure shows the definition of the disorder of the flat wire; the disorder is the maximum distance between the center of the kth turn coil and the center of the (k+1)th turn coil, denoted as D2. The distance between the center of the kth turn coil and the center of the (k+1)th turn coil can be any value between 2r and D2. If the error is assumed to be uniformly distributed, the probability of the k+1th turn coil appearing at all positions in the interval (2r, D) is equal. By defining the disorder of the winding D2, the arrangement of the uneven winding can be determined, that is, each turn is evenly placed within the distance (2r, D2) from the previous turn.

[0094] like Fig.13 As shown in the figure, it is a schematic diagram of winding distribution when the winding disorder degree takes different values; when the winding disorder degree takes different values ​​D, the unevenness of the winding is also different. The larger the value of D, the more obvious the uneven distribution of the winding; if the first turn of the winding is placed at the specified position, then there are m2 positions for the second turn in D, and m positions for the kth turn. k The number of possible positions of the next turn in D is m. i The product of the number of winding distributions increases with the number of turns n and the possible positions m i In fact, the possible position m of the next turn i The value of can be arbitrary, so the number of all winding distributions approaches infinity.

[0095] like Fig.14 The figure shows the possible positions of the unevenly distributed winding of the round wire; among them, the number of possible positions of the next turn is m i =3, so the total distribution of n turns of winding is 3 n The next possible position m i The number of all winding distributions is reduced by limiting them to certain values, with the goal of reducing the number of permutations with a similar distribution to the original one.

[0096] like Fig.15 The figure shows the possible positions of the unevenly distributed windings of the flat wire; the feasibility of this method is tested using the KS theorem. This is a test method to test whether the distribution of the original data sample is the same as the original data. It can be used to compare a sample with a specific probability distribution, and can also determine the distribution similarity of two samples. The specific proof is as follows:

[0097] like Fig.16 As shown in the figure, it is the probability distribution histogram of parasitic capacitance values ​​of large samples and small samples. Taking a 10-turn single-layer winding as an example, assuming that the position of the first turn is fixed, the possible position of the next turn is m i =4, so there are 4 winding distributions 9The parasitic capacitance values ​​calculated from all winding distributions are plotted as a histogram (as a large sample). Then the possible position m of the next turn is plotted. i =2, that is, there are 2 winding distributions 9 The distribution histogram of parasitic capacitance values ​​for all winding distributions when the sample is taken as a small sample. The KS test shows that this sample has a similar distribution to the smaller sample obtained by this method.

[0098] Step 4, calculating all possible parasitic capacitance values ​​of the winding according to the winding distribution probability model described in step 3;

[0099] According to the distribution of the winding, determine the adjacency pattern between adjacent turns and the corresponding integral angle when calculating the distributed capacitance. Use the energy method to calculate all possible distributed parasitic capacitance values ​​of the same winding when the winding disorder is D. The specific process is as follows:

[0100] First, place the first turn at the specified position. Set the number of possible positions for the next turn m i The value of Fig.11 A possible position is randomly selected within the possible interval (2r, D1) shown in the figure, and the same operation is performed on other turns. Through the above steps, a distribution of the winding can be obtained; then the parasitic capacitance of the winding distribution is calculated according to the energy method, and the above process is repeated many times to obtain the parasitic capacitance values ​​of all distributions in the winding.

[0101] Step 5: based on the parasitic capacitance calculation result, draw a distribution probability histogram of all possible parasitic capacitance values ​​of the winding when the winding disorder degree is D, where the value with the highest probability of occurrence is the predicted value of the total parasitic capacitance of the winding;

[0102] According to the calculation results, a probability histogram of parasitic capacitance values ​​for all possible distributions of the winding when the winding disorder is D is drawn. In this parasitic capacitance value probability histogram, a larger number belongs to the value with a high probability, which can predict the parasitic capacitance value in the winding during the design process.

[0103] Taking a toroidal excitation winding with 150 turns as an example, the winding disorder degree is D=3r, and the enameled wire is a round wire;

[0104] Specifies the number of possible positions for the next turn m i =3, then there are 3 winding distributions in total 150 kind.

[0105] Determine the distribution of the windings through simulation. Place the first turn at the specified position, and for the next turn, randomly select a possible position in the possible interval (2r, D). Do the same for the other turns. Through the above steps, a winding distribution can be obtained. The parasitic capacitance of the winding distribution is calculated according to the energy method. Repeat the above process many times to obtain the parasitic capacitance values ​​of all distributions in the winding.

[0106] The parasitic capacitance values ​​obtained under all distribution conditions are plotted as a histogram, such as Fig.17 As shown in the figure, the value with the highest probability of occurrence is the predicted value of the parasitic capacitance of the winding. Therefore, the parasitic capacitance of the winding is 106pF.

[0107] In this embodiment, for a toroidal winding with 150 turns, the winding disorder degree is D=3r, and the predicted value is 106pF. The parasitic capacitance value at the first resonant frequency measured by an impedance analyzer is 107.23pF. The predicted value is very close to the measured value.

Claims

1. A method for calculating the parasitic capacitance of a winding of an electromagnetic conversion device, characterized in that: The steps include: S1, establish an analytical model of multi-layer winding parasitic capacitance considering the turn-to-turn distance, and divide the distributed capacitance into turn-to-turn capacitance and layer-to-layer capacitance; S2, define the winding disorder, obtain the possible distribution position of each turn of the coil in the winding, and derive the analytical expressions of the inter-turn capacitance and inter-layer capacitance related to the winding disorder; S3, according to the parasitic capacitance analytical model of multi-layer windings, the calculation formula of the total parasitic capacitance of the windings is obtained; S4, and derive a probability model of the winding coil distribution according to the possible distribution position of each turn of the coil; and calculate all possible distribution values ​​of the winding parasitic capacitance according to the probability model of the winding coil distribution; S5, based on the calculation result of the winding parasitic capacitance, draw a distribution probability histogram of all possible parasitic capacitance values ​​of the winding when the winding disorder degree is D, where the value with the highest probability of occurrence is the predicted value of the total parasitic capacitance of the winding.

2. The method for calculating the parasitic capacitance of the winding of the electromagnetic conversion equipment according to claim 1, characterized in that: The capacitance formed between adjacent conductor turns in the same layer is the inter-turn capacitance; the capacitance formed between adjacent conductor turns in the same position in each layer is the inter-layer capacitance.

3. The method for calculating the parasitic capacitance of the winding of the electromagnetic conversion equipment according to claim 1, characterized in that: In step S2, when the cross section of the winding conductor is circular, the turn-to-turn capacitance C of the i-th winding layer is tti The expression is: In the formula, ε r is the relative dielectric constant of the wire insulation layer, ε0 is the vacuum dielectric constant, d tt D is the distance between adjacent turns of conductors. c D is the diameter of the copper core inside the conductor. o is the outer diameter of the wire; θ is the integral angle, the integral angle is from θ1 to θ2; l ti is the circumference of the i-th winding; When the cross section of the winding conductor is rectangular, the inter-turn capacitance C′ of the i-th winding layer is tti The expression is: Among them, d is the internal copper core width of the conductor, D′ is the outer layer width of the conductor, and d tt is the distance between turns of the conductor; h is the width of the insulation layer of the conductor.

4. The method for calculating the parasitic capacitance of the winding of the electromagnetic conversion equipment according to claim 1, characterized in that: The winding disorder degree is the maximum distance between the center of the kth coil and the center of the k+1th coil, denoted as D. The distance between the center of the kth coil and the center of the k+1th coil is any value between 2r and D, where r is the radius of the circular wire or half the width of the flat wire. Assuming that the error is uniformly distributed, the probability of the k+1th coil appearing at all positions in the interval (2r, D) is equal. If the first turn of the winding is placed at a given position, then there are m2 positions for the second turn within D, and m positions for the kth turn. k positions; let the number of possible positions of the next turn in D be m i , then the distribution of all n-turn windings is m i n .

5. The method for calculating the parasitic capacitance of the winding of the electromagnetic conversion equipment according to claim 1, characterized in that: In step S4, the implementation steps of calculating all possible parasitic capacitance values ​​of the winding are as follows: S41, place the first turn at the specified position and set the number of possible positions m for the next turn i The same operation is performed on the other turns to obtain a winding distribution; S42, determining the adjacency mode between adjacent turns and the corresponding integral angle according to the distribution of the winding; S43, when the disorder degree is D, all possible distributed parasitic capacitance values ​​of the same winding are calculated according to the energy method; S44, repeating steps S41 to S43 to obtain parasitic capacitance values ​​in all distribution situations in the winding.

Images