Construction method of composite functional planar magnetic coupling current sensor

Abstract

The invention discloses a construction method of a composite function type planar magnetic coupling current sensor, which comprises the following steps: constructing a circuit structure of the composite function type planar magnetic coupling current sensor, including a resonance compensation integral circuit and a buffer circuit; on the basis of the constructed power loop equivalent circuit and the structural parameters of the planar coil, obtaining circuit parameters to be solved in the buffer circuit to obtain a final buffer circuit; constructing a transfer function according to the structural parameters of the resistance voltage divider based on the resonance compensation integral circuit and the buffer circuit; constructing a parameter selection rule of a resonance compensation integral circuit, determining circuit parameters capable of compensating a resonance peak in the resonance signal acquired by the buffer circuit based on the transfer function, and acquiring a final resonance compensation integral circuit; and connecting the final buffer circuit and the final resonance compensation integral circuit through a resistance voltage divider to obtain the composite function type planar magnetic coupling current sensor. The problems that a traditional current sensor is single in function, switch oscillation suppression and switch current measurement generally depend on independent solutions, system complexity is increased, and layout standard requirements are strict are solved.

Description

Technical Field

[0001] The present invention relates to the technical fields of high-frequency switch oscillation suppression, switch current detection, current sensors and power electronics, and in particular to a method for constructing a composite functional planar magnetic coupling current sensor. Background Art

[0002] With the continuous advancement of power semiconductor technology, the switching speed of power switching devices has been significantly improved to meet the demand for higher efficiency and power density in power electronic converters. While faster switching speeds improve converter performance, they also bring numerous technical challenges. Specifically, increased switching speeds can induce severe switching oscillations, which not only result in additional power loss but also increase electromagnetic interference, adversely affecting the overall stability and reliability of the system. Furthermore, accurately measuring switching currents at the nanosecond level places higher technical demands and challenges on the performance and responsiveness of current sensors.

[0003] Various methods have been investigated to mitigate the adverse effects of switching oscillations, including optimizing circuit layout, employing active drivers, and introducing snubber circuits. Among these approaches, snubber circuits offer a relatively simple and low-cost solution. Compared to directly integrating snubber circuits into the power circuit, snubber circuits based on magnetic coupling reduce the risk of short circuits. However, due to the weak magnetic coupling, existing magnetic coupling snubber circuits struggle to achieve optimal suppression in high-frequency switching applications.

[0004] Existing switch current measurement methods can be broadly categorized as direct or indirect, depending on the measurement method. Direct measurement methods are simple in structure, with the most common method being the coaxial shunt. However, shunts are large, failing to meet the "small size" requirement. They are also costly and lack isolation, limiting their practical application. Rogowski coil current sensors are the most commonly used indirect measurement method. These sensors consist of an air-core coil and operate based on the Faraday principle of electromagnetic induction. When the conductor being measured passes through the coil, the current flowing through it generates an induced electromotive force, which reflects the measured current. Due to their use of an air-core coil, Rogowski coil current sensors inherently offer advantages such as high bandwidth and low intrusiveness. Traditional Rogowski coils typically increase the number of turns to increase mutual inductance, but this also increases the coil's parasitic parameters, reducing the sensor's bandwidth. Consequently, for traditional Rogowski coils, there is a clear conflict between high sensitivity and high bandwidth.

[0005] In summary, current traditional current sensors have a single function. Their switch oscillation suppression and switch current measurement usually rely on independent solutions, which leads to increased system complexity and strict layout standards. Summary of the Invention

[0006] The present invention provides a method for constructing a composite functional planar magnetic coupling current sensor to overcome the above technical problems.

[0007] In order to achieve the above object, the technical solution of the present invention is:

[0008] A method for constructing a composite functional planar magnetic coupling current sensor specifically comprises the following steps:

[0009] S1: Construction of the circuit structure of a composite functional planar magnetically coupled current sensor;

[0010] The circuit structure includes a resonant compensation integration circuit containing circuit parameters to be solved and a buffer circuit formed by a planar coil and a passive RC network;

[0011] The buffer circuit is used to suppress the switching oscillation during impedance coupling of the planar coil and obtain the resonant signal;

[0012] The resonant compensation integration circuit is used to compensate for the resonant signal output by the buffer circuit and integrate the output resonant signal to reconstruct the switching current signal;

[0013] S2: Based on the constructed power loop equivalent circuit and the structural parameters of the planar coil, the circuit parameters to be solved in the snubber circuit are obtained to obtain the final snubber circuit;

[0014] S3: constructing a transfer function based on the resonant compensation integrator circuit and the buffer circuit according to preset structural parameters of a resistor divider, wherein the resistor divider is defined to be located between the buffer circuit and the resonant compensation integrator circuit;

[0015] S4: Constructing parameter selection rules for the resonant compensation integration circuit, and confirming circuit parameters that can compensate for the resonant peak in the resonant signal obtained by the buffer circuit based on the transfer function, thereby obtaining a final resonant compensation integration circuit;

[0016] Then, the final buffer circuit and the final resonant compensation integration circuit are connected through a resistor divider to obtain a composite functional planar magnetic coupling current sensor.

[0017] Furthermore, the snubber circuit formed by the planar coil and the passive RC network constructed in S1 includes the planar coil and the passive RC network;

[0018] And the passive RC network includes the passive resistor R snb With passive capacitor C snb ;

[0019] The passive resistance R snb One end of the passive resistor R snb The other end of the passive capacitor C snbOne end of the passive capacitor C snb The other end of the planar coil is connected to the other end of the wiring.

[0020] Furthermore, the S2 specifically includes the following steps:

[0021] S21: Given power loop constraints:

[0022] That is, the positive and negative busbars of the power circuit are set to a single-turn ring structure;

[0023] The single-turn annular structure is used to generate a magnetic field in the central circular area surrounded by it when powered;

[0024] At the same time, the planar coil in the buffer circuit is arranged in the central circular area to achieve magnetic coupling between the single-turn ring structure and the planar coil;

[0025] S22: Based on the power loop constraints of S21, construct a power loop equivalent circuit with a buffer circuit, which includes a circuit power supply, a parasitic inductance L based on a single-turn ring structure equivalent setting loop , parasitic resistance R loop , output capacitor C oss , Planar coil self-inductance L snb , passive resistance R snb And the passive capacitor C snb ;

[0026] And the positive terminal of the circuit power supply and the parasitic inductance L loop One end is connected to the parasitic inductance L loop The other end of the parasitic resistance R loop One end is connected to the parasitic resistance R loop The other end of the output capacitor C oss One end of the output capacitor C oss The other end is connected to the negative terminal of the circuit power supply;

[0027] Planar coil self-inductance L snb One end of the passive resistor R snb One end of the passive resistor R snb The other end of the passive capacitor C snb One end of the passive capacitor C snb The other end of the planar coil self-inductance L snb The other end of the connection;

[0028] And the self-inductance L of the planar coil snb With parasitic inductance L loop The magnetic coupling connection forms a mutual inductance M, which in turn obtains an equivalent circuit of a power loop with a buffer circuit;

[0029] S23: Obtaining a total equivalent impedance based on a power loop equivalent circuit with a snubber circuit;

[0030] S24: Based on the total equivalent impedance, construct the passive capacitor C in the buffer circuit snb The parameter selection rules of the passive resistor R snb The parameter selection rules are used to confirm the circuit parameters to be solved in the buffer circuit and then obtain the final buffer circuit.

[0031] Furthermore, the formula for obtaining the total equivalent impedance in S23 is:

[0032]

[0033] Where: Z total (s) represents the total equivalent impedance; Z loop Represents the power loop impedance; Z snubber represents the impedance of the snubber circuit; M represents the mutual inductance between the equivalent power loop circuit and the equivalent snubber circuit; μ0 represents the vacuum magnetic permeability; R represents the inner radius of the ring busbar; n represents the number of turns of the planar coil; r out represents the outer radius of the planar coil; r in represents the inner radius of the planar coil; w and s represent the line width and line spacing of the planar coil respectively; L snb represents the self-inductance of a planar coil with n turns; Φ i,j It represents the magnetic flux generated by the i-th concentric loop in the area enclosed by the j-th turn of the planar coil; R i represents the inner radius of the annular busbar of the i-th concentric loop; N represents the number of concentric loops into which the power loop is divided; r j represents the outer radius of the j-th turn of the planar coil; p r Indicates the filling rate; r avg Indicates the intermediate parameter; i loop represents the current of the power circuit; b represents the line width of the concentric circuit; B w Indicates the width of a single-turn ring structure.

[0034] Furthermore, the passive capacitor C in the buffer circuit in S24 snb The expression of the parameter selection rule is: L loop C oss =L snb C snb ;

[0035] The passive resistance R snb The expression of the parameter selection rule is:

[0036]

[0037] Where: ω represents the angular frequency and ω=2πfr , f r Represents the resonant signal of the power circuit.

[0038] Furthermore, the resonant compensation integration circuit constructed in S1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first inductor L1, a first capacitor C1, a second capacitor C2 and an operational amplifier;

[0039] One end of the first resistor R1 is connected to one end of the second resistor R2 and the positive input terminal of the operational amplifier, the other end of the second resistor R2 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to one end of the third resistor R3;

[0040] The other end of the third resistor R3 is connected to the negative input end of the operational amplifier, one end of the second capacitor C2 and one end of the fourth resistor R4. The output end of the operational amplifier is connected to the other end of the second capacitor C2 and the other end of the fourth resistor R4.

[0041] Furthermore, the S3 specifically includes the following steps:

[0042] S31: setting a resistor voltage divider between the buffer circuit and the resonant compensation integration circuit;

[0043] The resistor divider includes a first voltage dividing resistor R s1 With the second voltage divider resistor R s2 ;

[0044] And the first voltage divider resistor R s1 One end of the buffer circuit is connected to the passive resistor R snb The other end of the first voltage divider resistor R s1 The other end of is connected to the other end of the first resistor R1 in the resonant compensation integration circuit;

[0045] The second voltage divider resistor R s2 One end of the buffer circuit is connected to the passive capacitor C snb The other end of the second voltage divider resistor R s2 The other end of is connected to the other end of the first capacitor C1 in the resonant compensation integration circuit;

[0046] S32: constructing a transfer function based on the resonant compensation integration circuit and the buffer circuit according to preset structural parameters of the resistor divider;

[0047] And the expression of the transfer function is

[0048]

[0049] Where: represents the transfer function of the buffer circuit; V snub (s) represents the passive capacitance C snb The voltage value at both ends; i loop (s) represents the current value of the power circuit; Represents the transfer function of the resonant compensation integrator circuit; V out (s) represents the voltage between the output terminal of the operational amplifier and one end of the third resistor R3; G Sen (s) represents the transfer function of the current sensor.

[0050] Furthermore, the parameter selection rule of the resonant compensation integration circuit constructed in S4 is expressed as follows:

[0051]

[0052] Where: f act1 Indicates the upper limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; f act2 It represents the lower limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; ζ represents the damping ratio of the resonance peak at the resonant signal; R s Represents the first voltage divider resistor R s1 With the second voltage divider resistor R s2 The resistance and.

[0053] Beneficial effects: The present invention provides a method for constructing a composite functional planar magnetic coupling current sensor, by integrating the switch oscillation suppression function and the high-frequency switch current measurement function into a sensor circuit, that is, constructing a circuit structure of a composite functional planar magnetic coupling current sensor; the present invention designs a power circuit equivalent circuit, that is, through the optimized design of the power circuit combined with the planar coil, significantly enhances the magnetic coupling between the power circuit and the sensor, significantly improves the oscillation suppression effect of the magnetic coupling buffer circuit and the sensitivity of the current sensor, and then optimizes the design of the buffer circuit parameters to maximize the system impedance; a resonant compensation integrator, that is, a resonant compensation integrator circuit is used to compensate for the resonant signal output by the buffer circuit to broaden the bandwidth of the sensor to reconstruct the switching current signal. The present invention solves the problem that the current switch oscillation suppression and switch current measurement usually rely on independent solutions, resulting in increased system complexity and strict layout requirements, by designing a current sensor with the dual functions of oscillation suppression and accurate current measurement. Through the functional reuse of planar magnetic components, the design difficulty of the system can be significantly simplified, while maintaining excellent performance in both oscillation suppression and current detection. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following is a brief introduction to the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0055] Figure 1 This is a flow chart of a method for constructing a composite functional planar magnetically coupled current sensor according to the present invention;

[0056] Figure 2 1 is an overall structural diagram of the composite functional planar magnetically coupled current sensor in this embodiment;

[0057] Figure 3 Schematic diagram of the equivalent circuit of the power loop with a buffer circuit in this embodiment;

[0058] Figure 4 In this embodiment, Z loop (S),Z total Bode plot of (S);

[0059] Figure 5 Flowchart of the buffer circuit design method in this embodiment;

[0060] Figure 6 In this embodiment, Z total (S) Impedance simulation diagram at the resonant signal;

[0061] Figure 7 is a frequency characteristic curve diagram of the current sensor in this embodiment;

[0062] Figure 8 This is a diagram of experimental results without using the constructed current sensor in this embodiment;

[0063] Figure 9 FIG is a diagram showing the experimental results of the current sensor constructed in this embodiment;

[0064] Figure 10 A comparison chart of the current sensor constructed in this embodiment and a commercial probe curve;

[0065] Figure 11 1 is a spectrum comparison diagram of the experimental results without using the constructed current sensor and with using the current sensor in this embodiment. DETAILED DESCRIPTION

[0066] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0067] This embodiment provides a method for constructing a composite functional planar magnetic coupling current sensor, such as Figure 1 As shown, the overall structure of the composite functional planar magnetic coupling current sensor proposed in this embodiment is shown in FIG. Figure 2 As shown, the sensor circuit consists of two parts: Part A, a buffer circuit formed by a planar coil and a passive RC network; Part B, a resistor divider and a resonant compensation integrator, namely a resonant compensation integrator circuit. Part A is responsible for coupling the impedance of the secondary side of the planar coil to the primary side to suppress switching oscillations; Part B is responsible for extracting the voltage across the capacitor of the buffer circuit to reconstruct the switching current signal. In this embodiment, the design process of the composite functional planar magnetic coupling current sensor is divided into: first, determining the structural parameters of the planar coil; then calculating the parameters of the passive RC network, namely the passive resistor R snb With passive capacitor C snb ; Then, the parameters of the resistor divider and the resonant compensation integrator are determined. In summary, the design scheme will be divided into four parts: including power circuit design and planar coil parameter calculation method, buffer circuit parameter selection, resonant compensation integrator circuit design and parameter selection, and experimental verification;

[0068] The specific steps include:

[0069] S1: Construction of the circuit structure of a composite functional planar magnetically coupled current sensor;

[0070] The circuit structure includes a resonant compensation integration circuit containing circuit parameters to be solved and a buffer circuit formed by a planar coil and a passive RC network;

[0071] The buffer circuit is used to suppress the switching oscillation during impedance coupling of the planar coil and obtain the resonant signal;

[0072] Specifically, the constructed buffer circuit includes a planar coil and a passive RC network; and the passive RC network includes a passive resistor R snb With passive capacitor C snb The passive resistor R snb One end of the passive resistor R snb The other end of the passive capacitor C snb One end of the passive capacitor C snbThe other end of is connected to the other end of the wire in the planar coil;

[0073] The resonant compensation integration circuit is used to compensate for the resonant signal output by the buffer circuit and integrate the output resonant signal to reconstruct the switching current signal;

[0074] Specifically, the constructed resonant compensation integration circuit includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first inductor L1, a first capacitor C1, a second capacitor C2, and an operational amplifier; one end of the first resistor R1 is connected to one end of the second resistor R2 and the positive input terminal of the operational amplifier, the other end of the second resistor R2 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to one end of the third resistor R3; the other end of the third resistor R3 is connected to the negative input terminal of the operational amplifier, one end of the second capacitor C2, and one end of the fourth resistor R4, and the output end of the operational amplifier is connected to the other end of the second capacitor C2 and the other end of the fourth resistor R4;

[0075] S2: Based on the constructed power loop equivalent circuit and the structural parameters of the planar coil, the circuit parameters to be solved in the snubber circuit are obtained to obtain the final snubber circuit. Specifically, the following steps are included:

[0076] S21: Given power loop constraints:

[0077] That is, the positive and negative busbars of the power circuit are set to a single-turn ring structure;

[0078] The single-turn annular structure is used to generate a strong magnetic field in the central circular area surrounded by it when powered;

[0079] At the same time, the planar coil in the buffer circuit is arranged in the central circular area to achieve magnetic coupling between the single-turn ring structure and the planar coil;

[0080] S22: Based on the power loop constraints of S21, construct a power loop equivalent circuit with a buffer circuit, which includes a circuit power supply, a parasitic inductance L based on a single-turn ring structure equivalent setting loop , parasitic resistance R loop , output capacitor C oss , Planar coil self-inductance L snb , passive resistance R snb And the passive capacitor C snb ;

[0081] And the positive terminal of the circuit power supply and the parasitic inductance L loop One end is connected to the parasitic inductance L loop The other end of the parasitic resistance R loopOne end is connected to the parasitic resistance R loop The other end of the output capacitor C oss One end of the output capacitor C oss The other end is connected to the negative terminal of the circuit power supply;

[0082] Planar coil self-inductance L snb One end of the passive resistor R snb One end of the passive resistor R snb The other end of the passive capacitor C snb One end of the passive capacitor C snb The other end of the planar coil self-inductance L snb The other end of the connection;

[0083] And the self-inductance L of the planar coil snb With parasitic inductance L loop The magnetic coupling connection forms a mutual inductance M, which in turn obtains an equivalent circuit of a power loop with a buffer circuit;

[0084] The current sensor proposed in this embodiment senses the magnetic field generated by the power circuit through a planar coil, thereby suppressing switching oscillation and detecting current signals. Figure 3 The equivalent circuit of the power loop including the snubber circuit is shown. loop With R loop Respectively represent the parasitic inductance and parasitic resistance of the power circuit, C oss represents the output capacitance of SiC MOSFET, while for the snubber circuit, L snb Represents the self-inductance of the planar coil, R snb with C snb are the resistance and capacitance of the snubber circuit respectively;

[0085] S23: Obtaining a total equivalent impedance based on a power loop equivalent circuit with a snubber circuit;

[0086] In this embodiment, the mutual inductance M between the power circuit and the planar coil represents the magnetic coupling strength between the two. A larger mutual inductance helps to enhance the suppression effect of high-frequency oscillation and improve the sensitivity of the current sensor. Figure 3 As shown, in order to improve the magnetic coupling strength between the planar coil and the power circuit, the positive and negative busbars of the power circuit are flexibly designed as a single-turn ring structure with a width of B. w This design can enhance the magnetic field strength in the central circular area surrounded by the ring structure, and placing the planar coil in this area can achieve magnetic coupling with the positive and negative busbars at the same time. According to Faraday's law of electromagnetic induction, the calculation formula for mutual inductance is as follows:

[0087]

[0088] Where: iloop Indicates the current of the power circuit; Φ indicates i loop To accurately calculate the mutual inductance, the width of the ring busbar B must be considered. w Impact on mutual inductance calculation; such as Figure 3 As shown, in this embodiment, the ring bus is hypothetically divided into concentric loops with a line width of b. When b is small enough, the influence of the conductor width on the mutual inductance calculation can be ignored. Therefore, the total mutual inductance M can be obtained by summing the mutual inductance between each concentric loop and the planar coil. The formula is:

[0089]

[0090] Where: M represents the magnetic coupling strength between the equivalent power loop circuit and the equivalent snubber circuit; μ0 represents the vacuum magnetic permeability; R represents the inner radius of the ring busbar; n represents the number of turns of the planar coil; r out represents the outer radius of the planar coil; r in Indicates the inner radius of the planar coil; w and s represent the line width and line spacing of the planar coil respectively; Φ i,j It represents the magnetic flux generated by the i-th concentric loop in the area enclosed by the j-th turn of the planar coil; R i represents the inner radius of the annular busbar of the i-th concentric loop; N represents the number of concentric loops into which the power loop is divided; r j represents the outer radius of the j-th turn of the planar coil; b represents the line width of the concentric loop; B w Represents the width of a single-turn ring structure. Another important parameter of the planar coil is its self-inductance L snb , and the self-inductance calculation formula of the n-turn planar coil is:

[0091]

[0092] Where: L snb represents the self-inductance of the n-turn planar coil; p r ,r avg They represent the filling rate and the intermediate parameter respectively, and their expressions are:

[0093]

[0094] In this embodiment, the switching oscillation is caused by the output capacitor C oss With parasitic inductance L loop If the resonance between Figure 3 The impedance of the snubber circuit in the system is equivalent to the power circuit, so the total equivalent impedance of the system is Z total (s), whose expression is:

[0095]

[0096] like Figure 4 The figure shows Z loop With Z total (s) impedance characteristic curve, it can be clearly seen that Z snubber Represents the impedance of the buffer circuit; Z loop Represents the power circuit impedance, so the power circuit will have switching oscillation, and the frequency of the switching oscillation is equal to L loop with C oss The resonance signal f r , this embodiment can improve the impedance of the system at the resonant signal by introducing a buffer circuit, thereby effectively suppressing the switching oscillation;

[0097] S24: Based on the total equivalent impedance, construct the passive capacitor C in the buffer circuit snb The parameter selection rules of the passive resistor R snb Parameter selection rules are used to confirm the circuit parameters to be solved in the buffer circuit and then obtain the final buffer circuit;

[0098] Specifically, for the buffer circuit in this embodiment, the mutual inductance M and the self-inductance L snb , resistor R snb With capacitor C snb The selection of R will directly affect the suppression effect of the snubber circuit on the switching oscillation. Therefore, this section first explains the principle of the snubber circuit suppressing oscillation from the perspective of impedance, and then explains the R with the goal of achieving the best impedance improvement effect. snb with C snb The selection principle is finally used to select the ones that meet the design requirements (r min ≤r out ≤r max , n min ≤n≤n max ) to select the plane coil parameters and obtain the corresponding R snb with C snb , in order to select a set of buffer circuit parameters (R snb ,C snb );

[0099] In order to achieve the above purpose, the embodiment needs to keep the resonant signal of the buffer circuit consistent with the power loop, so the passive capacitor C in the buffer circuit snb The parameter selection rules should meet the following conditions:

[0100] L loop C oss =L snb C snb (8)

[0101] Next, we will explore R snb The impact on the impedance at the resonant signal, such as Figure 4 Shows different R snb To Z total (s), and it can be known that as R snb The resistance decreases, Z total (s) at the resonance signal f r The impedance at the point increases, however, when R snb If the resistance is too small, it will r Two additional resonance peaks are introduced on both sides, which will lead to poor oscillation suppression effect; therefore, R needs to be selected carefully. snb To avoid the above phenomenon, Figure 4 The phase-frequency characteristic curve can be observed, regardless of R snb What value should be chosen, Z total The phase-frequency curve of (s) will be at a fixed point P r Intersect at snb The resistance value increases, Z total The slope of the phase-frequency curve of (s) changes from negative to positive near the resonant signal. total (s) The impedance at the resonance point decreases accordingly; therefore, in order to maximize the impedance at the resonance signal while avoiding the introduction of additional resonance peaks, R snb The selection of passive resistor R snb Parameter selection rules:

[0102]

[0103] Where: ω represents the angular frequency and ω=2πf r , f r Represents the resonant signal of the power circuit; ∠ represents the phase angle of the resonant signal;

[0104] In the actual buffer circuit design of this embodiment, it is first necessary to determine the outer radius r of the planar coil. out and the number of coil turns n, because they determine the mutual inductance M and self-inductance L of the snubber circuit snb ; Then, according to formulas (7)-(9), we can further derive C snb ,R snb ,Z total (s); such as Figure 5 As shown, by using the enumeration method to scan r out ,n, to obtain the parameters of the buffer circuit and Z under different planar coil structure parameters total (s) at the resonance signal f r The specific process is as follows:

[0105] S001: First, initialize the parameters randomly;

[0106] The randomly initialized parameters include the power circuit parameters R, B w ,b,L loop ,C oss ,R loop ; Planar coil parameters r out ,n,w,s; the maximum outer diameter r of the planar coil max and minimum outer diameter r min , maximum number of turns n max and the minimum number of turns n min ; n = n min , r out =r min ;

[0107] S002: Judge r out ≤r max Is it true? If so, execute S003; otherwise, end the loop;

[0108] S003: Judgment n≤n max Is it true? If so, execute S004; otherwise, set n=n min And execute S006;

[0109] S004: Obtain buffer circuit parameters M, L according to formulas (1)-(9) snb ,C snb ,R snb ,Z total (s), and store the results;

[0110] S005: Execute n=n+1 and return to step S003;

[0111] S006: Execute r out =r out +Δr, and return to step S002; where Δr represents r out the increment;

[0112] The specific results are as shown in Table 1, and Z total (s) The impedance at the resonant signal is as follows Figure 6 As shown, from Figure 6 It can be concluded that, compared with increasing the number of turns, increasing the outer diameter r of the planar coil out It is more effective to improve the impedance at the resonant signal; at the same r out Increasing the number of turns n will increase the mutual inductance M and improve the sensitivity of the sensor, but it will also increase the difficulty of designing the sensor circuit. Therefore, after weighing the expert experience, r was finally selected. out =15mm, n=8 coil parameters for subsequent sensor design, and then when the outer radius r of the planar coil out After the number of turns n is determined, the M and L of the snubber circuit can be obtained.snb To determine C snb ,R snb ;

[0113] Table 1. Power circuit and planar coil parameters

[0114] parameter value <![CDATA[B w ]]> 4mm b 35μm R 16mm <![CDATA[L loop ]]> 400nH <![CDATA[C oss ]]> 375pF <![CDATA[R loop ]]> 0.45Ω w 0.125mm s 0.125mm <![CDATA[r min ,r max ]]> 6mm, 15mm <![CDATA[n min ,n max ]]> 1，20

[0115] S3: Based on the resonant compensation integrator circuit and the buffer circuit, a transfer function is constructed according to the structural parameters of a preset resistor divider, wherein the resistor divider is defined to be located between the buffer circuit and the resonant compensation integrator circuit, specifically comprising the following steps:

[0116] S31: setting a resistor voltage divider between the buffer circuit and the resonant compensation integration circuit;

[0117] The resistor divider includes a first voltage dividing resistor R s1 With the second voltage divider resistor R s2 ;

[0118] And the first voltage divider resistor R s1 One end of the buffer circuit is connected to the passive resistor R snb The other end of the first voltage divider resistor R s1 The other end of is connected to the other end of the first resistor R1 in the resonant compensation integration circuit;

[0119] The second voltage divider resistor R s2 One end of the buffer circuit is connected to the passive capacitor C snb The other end of the second voltage divider resistor R s2 The other end of is connected to the other end of the first capacitor C1 in the resonant compensation integration circuit;

[0120] In this embodiment, after completing the buffer circuit design, the next step is to design the corresponding resistor voltage divider circuit and resonant compensation integration circuit, such as Figure 2 As shown, to ensure that the input voltage of the operational amplifier remains within its safe operating range, a resistor consisting of R is inserted between the resonant compensation integrator and the buffer. s1 and R s2 In order to minimize the impact of the voltage divider circuit on the oscillation suppression function of the buffer circuit, it is necessary to select a relatively high resistance value R based on expert experience. s1 and R s2 Its unit is kΩ;

[0121] S32: constructing a transfer function based on the resonant compensation integration circuit and the buffer circuit according to preset structural parameters of the resistor divider;

[0122] And the expression of the transfer function is

[0123]

[0124] Where: represents the transfer function of the buffer circuit; V snub (s) represents the passive capacitance C snb The voltage value at both ends; i loop (s) represents the current value of the power circuit; Represents the transfer function of the resonant compensation integrator circuit; V out (s) represents the voltage between the output terminal of the operational amplifier and one end of the third resistor R3; G Sen (s) represents the transfer function of the current sensor.

[0125] According to formulas (10) and (11), the frequency characteristic curve of the current sensor can be obtained as follows: Figure 7 As shown, due to L snb with C snb Resonance occurs between the two circuits, causing the frequency characteristic curve of the A part circuit to be at the resonance signal f r A clear resonance peak appears at the part, which will significantly reduce the measurement bandwidth of the current sensor. To overcome this limitation and ensure accurate measurement of high-speed switching current, this embodiment uses a resonance compensation integrator in part B to compensate for the resonance peak of part A to expand the bandwidth of the sensor. Figure 7 Part B shown in the figure introduces a notch link at the resonant signal, effectively suppressing the resonant peak of part A; therefore, the transfer function of the current sensor G Sen (s) It can show stable gain over a wider frequency range, thereby improving the accuracy of the sensor in measuring the switching current waveform;

[0126] S4: Constructing parameter selection rules for the resonant compensation integration circuit, and confirming circuit parameters that can compensate for the resonant peak in the resonant signal obtained by the buffer circuit based on the transfer function, thereby obtaining a final resonant compensation integration circuit;

[0127] Specifically, the parameter selection rule of the constructed resonant compensation integration circuit is expressed as follows:

[0128]

[0129] Where: f act1 Indicates the upper limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; f act2 It represents the lower limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; ζ represents the damping ratio of the resonance peak at the resonant signal; R s Represents the first voltage divider resistor R s1 With the second voltage divider resistor R s2 The resistance value and, in this embodiment, the parameters of the resonant compensation integrator can be selected by formulas (12) and (13);

[0130] Then, the final buffer circuit and the final resonant compensation integration circuit are connected through a resistor divider to obtain a composite functional planar magnetic coupling current sensor.

[0131] Experimental verification:

[0132] This embodiment uses a dual-pulse test circuit to further verify the feasibility and dual functions of the constructed composite functional planar magnetic coupling current sensor; in this experiment, f is set to act1 is 30kHz; set f act2 The key parameters of the sensor are calculated based on formulas (12) and (13) and are shown in Table 2.

[0133] Table 2. Key parameters of current sensors

[0134] parameter value parameter value M 230nH <![CDATA[R2]]> 32Ω <![CDATA[L snb ]]> 3.67μH <![CDATA[R3]]> 120Ω <![CDATA[R snb ]]> 55Ω <![CDATA[R4]]> 100kΩ <![CDATA[R s1 ]]> 7kΩ <![CDATA[C1]]> 81pF <![CDATA[R s2 ]]> 3kΩ <![CDATA[C2]]> 2.2nF <![CDATA[R1]]> 1.17kΩ <![CDATA[L1]]> 1.8μH

[0135] According to formulas (10) and (11), the sensitivity of the current sensor is 0.255V / A. Figure 8 The double pulse experimental results without the proposed current sensor are shown. gs represents the gate-source voltage; i loop Represents the loop current measured by a commercial current probe; V ds represents the drain-source voltage of SiC MOSFET. During the switching process of the current sensor, it can be observed that the current and voltage of SiC MOSFET have severe oscillations. In contrast, Figure 9 The experimental results using the proposed current sensor are shown. out Represents the output voltage of the current sensor, which is Figure 8 By comparing the switching current and voltage waveforms in the example, it is found that both voltage and current oscillations are well suppressed after using the current sensor. Therefore, the buffering function is well verified. In addition, the switching current waveform measured by the proposed current sensor is overlapped with the waveform measured by a commercial current probe to verify the current sensor's ability to measure high-frequency current. Figure 10 It can be seen that the current waveforms measured by the two are almost overlapping, and the high-frequency switching current is accurately measured. Figure 11 The spectrum of the experimental waveforms without and with the current sensor is shown. When the proposed current sensor is used, V ds with i loop The spectrum peak of is reduced by about 10dB, such as Figure 11As shown, by comparing the spectrum of the current sensor output voltage with the spectrum of the commercial current probe, it can be seen that the spectra of the two are basically consistent. In summary, it can be seen that the experimental results fully confirm that the composite functional planar magnetic coupling current sensor constructed in this embodiment has the dual functions of oscillation suppression and accurate current measurement.

[0136] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for constructing a composite functional planar magnetic coupling current sensor, characterized in that: The specific steps include: S1: Construction of the circuit structure of a composite functional planar magnetically coupled current sensor; The circuit structure includes a resonant compensation integration circuit containing circuit parameters to be solved and a buffer circuit formed by a planar coil and a passive RC network; The buffer circuit is used to suppress the switching oscillation during impedance coupling of the planar coil and obtain the resonant signal; The resonant compensation integration circuit is used to compensate for the resonant signal output by the buffer circuit and integrate the output resonant signal to reconstruct the switching current signal; S2: Based on the constructed power loop equivalent circuit and the structural parameters of the planar coil, the circuit parameters to be solved in the snubber circuit are obtained to obtain the final snubber circuit; S3: constructing a transfer function based on the resonant compensation integrator circuit and the buffer circuit according to preset structural parameters of a resistor divider, wherein the resistor divider is defined to be located between the buffer circuit and the resonant compensation integrator circuit; S4: Constructing parameter selection rules for the resonant compensation integration circuit, and confirming circuit parameters that can compensate for the resonant peak in the resonant signal obtained by the buffer circuit based on the transfer function, thereby obtaining a final resonant compensation integration circuit; Then, the final buffer circuit and the final resonant compensation integration circuit are connected through a resistor divider to obtain a composite functional planar magnetic coupling current sensor.

2. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 1, characterized in that: The snubber circuit formed by the planar coil and the passive RC network constructed in S1 includes a planar coil and a passive RC network; And the passive RC network includes the passive resistor R snb With passive capacitor C snb ; The passive resistance R snb One end of the passive resistor R snb The other end of the passive capacitor C snb One end of the passive capacitor C snb The other end of the planar coil is connected to the other end of the wiring.

3. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 2, characterized in that: The S2 specifically includes the following steps: S21: Given power loop constraints: That is, the positive and negative busbars of the power circuit are set to a single-turn ring structure; The single-turn annular structure is used to generate a magnetic field in the central circular area surrounded by it when powered; At the same time, the planar coil in the buffer circuit is arranged in the central circular area to achieve magnetic coupling between the single-turn ring structure and the planar coil; S22: Based on the power loop constraints of S21, construct a power loop equivalent circuit with a buffer circuit, which includes a circuit power supply, a parasitic inductance L based on a single-turn ring structure equivalent setting loop , parasitic resistance R loop , output capacitor C oss , Planar coil self-inductance L snb , passive resistance R snb And the passive capacitor C snb ; And the positive terminal of the circuit power supply and the parasitic inductance L loop One end is connected to the parasitic inductance L loop The other end of the parasitic resistance R loop One end is connected to the parasitic resistance R loop The other end of the output capacitor C oss One end of the output capacitor C oss The other end is connected to the negative terminal of the circuit power supply; Planar coil self-inductance L snb One end of the passive resistor R snb One end of the passive resistor R snb The other end of the passive capacitor C snb One end of the passive capacitor C snb The other end of the planar coil self-inductance L snb The other end of the connection; And the self-inductance L of the planar coil snb With parasitic inductance L loop The magnetic coupling connection forms a mutual inductance M, which in turn obtains an equivalent circuit of a power loop with a buffer circuit; S23: Obtaining a total equivalent impedance based on a power loop equivalent circuit with a snubber circuit; S24: Based on the total equivalent impedance, construct the passive capacitor C in the buffer circuit snb The parameter selection rules of the passive resistor R snb The parameter selection rules are used to confirm the circuit parameters to be solved in the buffer circuit and then obtain the final buffer circuit.

4. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 3, characterized in that: The formula for obtaining the total equivalent impedance described in S23 is: Where: Z total (s) represents the total equivalent impedance; Z loop Represents the power loop impedance; Z snubber represents the impedance of the snubber circuit; M represents the mutual inductance between the equivalent power loop circuit and the equivalent snubber circuit; μ0 represents the vacuum magnetic permeability; R represents the inner radius of the ring busbar; n represents the number of turns of the planar coil; r out represents the outer radius of the planar coil; r in represents the inner radius of the planar coil; w and s represent the line width and line spacing of the planar coil respectively; L snb represents the self-inductance of a planar coil with n turns; Φ i,j It represents the magnetic flux generated by the i-th concentric loop in the area enclosed by the j-th turn of the planar coil; R i represents the inner radius of the annular busbar of the i-th concentric loop; N represents the number of concentric loops into which the power loop is divided; r j represents the outer radius of the j-th turn of the planar coil; p r Indicates the filling rate; r avg Indicates the intermediate parameter; i loop represents the current of the power circuit; b represents the line width of the concentric circuit; B w Indicates the width of a single-turn ring structure.

5. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 4, characterized in that: The passive capacitor C in the buffer circuit described in S24 snb The expression of the parameter selection rule is: L loop C oss =L snb C snb ; The passive resistance R snb The expression of the parameter selection rule is: Where: ω represents the angular frequency and ω=2πf r , f r Represents the resonant signal of the power circuit.

6. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 5, characterized in that: The resonant compensation integration circuit constructed in S1 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first inductor L1, a first capacitor C1, a second capacitor C2 and an operational amplifier; One end of the first resistor R1 is connected to one end of the second resistor R2 and the positive input terminal of the operational amplifier, the other end of the second resistor R2 is connected to one end of the first inductor L1, the other end of the first inductor L1 is connected to one end of the first capacitor C1, and the other end of the first capacitor C1 is connected to one end of the third resistor R3; The other end of the third resistor R3 is connected to the negative input end of the operational amplifier, one end of the second capacitor C2 and one end of the fourth resistor R4. The output end of the operational amplifier is connected to the other end of the second capacitor C2 and the other end of the fourth resistor R4.

7. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 6, characterized in that: The S3 specifically includes the following steps: S31: setting a resistor voltage divider between the buffer circuit and the resonant compensation integration circuit; The resistor divider includes a first voltage dividing resistor R s1 With the second voltage divider resistor R s2 ; And the first voltage divider resistor R s1 One end of the buffer circuit is connected to the passive resistor R snb The other end of the first voltage divider resistor R s1 The other end of is connected to the other end of the first resistor R1 in the resonant compensation integration circuit; The second voltage divider resistor R s2 One end of the buffer circuit is connected to the passive capacitor C snb The other end of the second voltage divider resistor R s2 The other end of is connected to the other end of the first capacitor C1 in the resonant compensation integration circuit; S32: constructing a transfer function based on the resonant compensation integration circuit and the buffer circuit according to preset structural parameters of the resistor divider; And the expression of the transfer function is Where: represents the transfer function of the buffer circuit; V snub (s) represents the passive capacitance C snb The voltage value at both ends; i loop (s) represents the current value of the power circuit; Represents the transfer function of the resonant compensation integrator circuit; V out (s) represents the voltage between the output terminal of the operational amplifier and one end of the third resistor R3; G Sen (s) represents the transfer function of the current sensor.

8. The method for constructing a composite functional planar magnetic coupling current sensor according to claim 7, characterized in that: The expression of the parameter selection rule of the resonant compensation integration circuit constructed in S4 is: Where: f act1 Indicates the upper limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; f act2 It represents the lower limit of the integration frequency of the active integrator, i.e. the resonant compensation integration circuit; ζ represents the damping ratio of the resonance peak at the resonant signal; R s Represents the first voltage divider resistor R s1 With the second voltage divider resistor R s2 The resistance and.

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