A high-frequency magnetic element winding ac resistance measurement correction method

Abstract

The application discloses a high-frequency magnetic element winding AC resistance measurement correction method, comprising the following steps: measuring the leakage impedance of a measured winding; measuring and obtaining the frequency characteristic curve of the total leakage impedance of the measured winding and an auxiliary winding; fitting the characteristic parameters in the total leakage impedance of the measured winding and the auxiliary winding according to the frequency characteristic curve; calculating the error coefficient according to the characteristic parameters; and calculating the AC resistance of the measured winding according to the leakage impedance of the measured winding and the error coefficient. The method can effectively improve the measurement precision and the measurement frequency range of the AC resistance of the winding of the high-power high-frequency magnetic element, and reduce the influence of the coupling capacitance between the auxiliary winding and the measured winding on the measurement precision.

Description

TECHNICAL FIELD

[0001] The application relates to a high-frequency magnetic element winding AC resistance measurement correction method and belongs to the field of parameter measurement of transformers, inductors and other magnetic elements. BACKGROUND

[0002] Increasing the working frequency of transformers, inductors and other magnetic elements is a main means for greatly reducing the volume and mass of the magnetic elements, and provides the possibility of improving system power density and reducing system cost. In the design of high-power high-frequency magnetic elements, adopting a Litz wire winding is an effective method for reducing the loss of the high-frequency winding. The complex structure of the Litz wire winding makes it very difficult to calculate the winding AC resistance, and therefore, it is of great significance to study a reliable winding loss measurement method.

[0003] In order to reduce the influence of the induced voltage in the magnetic element on the measurement precision of the winding AC resistance, setting an auxiliary winding in the magnetic element to introduce an additional measurement node is an effective method for improving the measurement precision. The coupling degree between the auxiliary winding and the measured winding determines the measurable winding resistance value range and the frequency range, however, the coupling capacitance between the auxiliary winding and the measured winding limits the improvement of the measurement frequency, and the capacitive current injected into the auxiliary winding through the coupling capacitance at a high frequency will result in the decrease of the AC resistance measurement precision. At present, the winding AC resistance measurement method based on the auxiliary winding is affected by the coupling capacitance, and cannot accurately measure the winding AC resistance at a high frequency. SUMMARY

[0004] The technical problem to be solved by the application is to provide a high-frequency magnetic element winding AC resistance measurement correction method, which can effectively improve the measurement precision and the measurement frequency range of the winding AC resistance of a high-power high-frequency magnetic element, and reduce the influence of the coupling capacitance between the auxiliary winding and the measured winding on the measurement precision.

[0005] The application adopts the following technical solution to solve the above technical problem:

[0006] A high-frequency magnetic element winding AC resistance measurement correction method, in which an auxiliary winding is set in a high-frequency magnetic element, the influence of the coupling capacitance between the auxiliary winding and the measured winding is considered, and the AC resistance value of the measured winding is corrected; the method comprises the following steps:

[0007] Step 1, measuring the leakage impedance of the measured winding;

[0008] Step 2, measuring and obtaining the frequency characteristic curve of the total leakage impedance of the measured winding and the auxiliary winding;

[0009] Step 3, fitting the characteristic parameters in the total leakage impedance of the measured winding and the auxiliary winding according to the frequency characteristic curve of step 2;

[0010] Step 4, calculating the error coefficient according to the characteristic parameters.

[0011] Step 5, calculating the AC resistance of the measured winding according to the measured leakage impedance of the winding and the error coefficient.

[0012] As a preferred scheme of the present application, in step 1, the leakage impedance of the measured winding is measured by the impedance measuring instrument, and the low potential interface of the current excitation branch and the reference ground interface of the voltage measurement of the impedance measuring instrument are connected to the same end of the measured winding, the voltage measurement point interface of the impedance measuring instrument is connected to one end of the auxiliary winding, the other ends of the measured winding and the auxiliary winding are short-circuited to each other and connected to the high potential interface of the current excitation branch of the impedance measuring instrument, and the same end of the measured winding and the auxiliary winding which are short-circuited to each other is the same end.

[0013] As a preferred scheme of the present application, the expression of the leakage impedance of the measured winding in step 1 is:

[0014] Z AW = K c (r1+jωl1)

[0015] wherein Z AW is the leakage impedance of the measured winding, K c is the error coefficient, c is the equivalent coupling capacitance between the measured winding and the auxiliary winding, r1 and r2 are respectively the AC resistance of the measured winding and the auxiliary winding, l1 and l2 are respectively the leakage inductance of the measured winding and the auxiliary winding, ω is the measurement frequency, ω r , and ξ are characteristic parameters, and j is the imaginary unit.

[0016] As a preferred scheme of the present application, the expression of the total leakage impedance of the measured winding and the auxiliary winding is:

[0017]

[0018] wherein Z Aa is the total leakage impedance of the measured winding and the auxiliary winding, c is the equivalent coupling capacitance between the measured winding and the auxiliary winding, ω is the measurement frequency, ω r , and ξ are characteristic parameters, and j is the imaginary unit.

[0019] As a preferred scheme of the present application, the measurement circuit required for calculating the error coefficient in step 4 is that the low potential interface of the current excitation branch and the reference ground interface of the voltage measurement of the impedance measuring instrument are connected to the same end of the measured winding, the voltage measurement point interface and the high potential interface of the current excitation branch of the impedance measuring instrument are connected to the same end of the auxiliary winding, the other ends of the measured winding and the auxiliary winding are short-circuited to each other, and the same end of the measured winding and the auxiliary winding which are short-circuited to each other is the same end.

[0020] As a preferred scheme of the present application, the measured winding AC resistance in step 5 is the real part of the ratio of the leakage impedance of the measured winding to the error coefficient.

[0021] Compared with the prior art, the present application has the following technical effects:

[0022] 1. The winding AC resistance measurement correction method considers the influence of the coupling capacitance between the auxiliary winding and the measured winding, and improves the winding resistance measurement accuracy.

[0023] 2. The winding AC resistance measurement correction method expands the frequency range of winding resistance measurement. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 is the leakage impedance of the measured winding in the present application AW measurement schematic diagram.

[0025] Figure 2 is the equivalent circuit diagram of the measured winding and the auxiliary winding in the present application.

[0026] Figure 3 is the total leakage impedance of the measured winding and the auxiliary winding in the present application Aa measurement schematic diagram.

[0027] Figure 4 is the frequency characteristic curve of the total leakage impedance of the measured winding and the auxiliary winding in the present application Aa .

[0028] Figure 5 is the flow chart of the winding AC resistance measurement correction method of the high-frequency magnetic element in the present application. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical scheme and advantages of the present application clearer, the present application will be further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application. In addition, the technical features involved in each embodiment of the present application described below can be combined with each other as long as they do not conflict with each other. The implementation of the technical scheme will be further described in detail below in combination with the drawings.

[0030] As Figure 1The diagram illustrates a method for measuring the AC resistance of a winding. This embodiment includes an impedance measuring instrument 3, a winding under test 1, and an auxiliary winding 2. To reduce the impact of the leakage magnetic field between the winding under test 1 and the auxiliary winding 2 on the measurement accuracy and to improve the measurement frequency range, the auxiliary winding 2 should be tightly coupled to the winding under test 1. If the winding under test 1 is a Litz wire winding, a single strand of Litz wire can be selected as the auxiliary winding 2. If the winding under test 1 is a copper foil winding, a thin copper foil tightly fitted to the winding under test 1 can be selected as the auxiliary winding 2. There should be an insulating layer between the copper foil winding under test and the thin copper foil used as the auxiliary winding. The impedance measuring instrument 3 has a four-terminal impedance measurement interface: H CUR (High potential in current excitation branch), H POT (Voltage measurement point), L POT (Voltage measurement reference ground), L CUR (Low potential in the current-excited branch). H CUR Connect the common potential terminals B and H of the tested winding 1 and auxiliary winding 2. POT Connect terminal a of auxiliary winding 2, L POT Connect terminal A of the winding 1 under test, L CUR Connect terminal A of the winding 1 under test.

[0031] like Figure 2 As shown, it gives Figure 1 The equivalent circuit diagram of the tested winding 1 and the auxiliary winding 2 is shown. There is an equivalent coupling capacitance c between the A end of the tested winding 1 and the a end of the auxiliary winding 2. The leakage inductance of the tested winding 1 is l1 and the leakage inductance of the auxiliary winding 2 is l2. The AC resistances of the tested winding 1 and the auxiliary winding 2 at the measurement frequency ω are r1 and r2, respectively.

[0032] according to Figure 2 The equivalent circuit shown. Figure 1 The impedance measured by the impedance measuring instrument 3 is the leakage impedance Z of the winding under test. AW The expression is Z AW =K c (r1+jωl1). Leakage impedance Z of the winding under test. AW The coefficient K in the expression c To and Figure 2 The parameters of the equivalent circuit shown are related and defined as the error coefficient K. c The expression is: in ω is the measurement frequency. Based on the leakage impedance Z of the winding under test... AW The expression for the error coefficient K, if the equivalent coupling capacitance c is not considered, is as follows: c =1, leakage impedance Z of the measured winding AWThe real part of the value is the AC resistance r1 of the measured winding 1. However, in actual measurement systems, the equivalent coupling capacitance c must exist, and when the measurement frequency ω approaches the resonant frequency ω... r At that time, the error coefficient K c The value tends to -j / (2ξ), causing the leakage impedance Z of the measured winding to... AW The real part deviates from the AC resistance r1 of the measured winding 1.

[0033] In order to correct the error coefficient K c The resulting AC resistance measurement error requires obtaining the coefficient K at the measurement frequency ω. c The actual value. Figure 3 The calculation error coefficient K is given. c Required measurement circuitry. Figure 3 In the middle, the impedance measuring instrument 3's L CUR and L POT The impedance measuring instrument 3 connects to terminal A of the winding under test 1, and to terminal H of the winding under test 1. POT and H CUR The a-end of the auxiliary winding 2 is connected to the b-end of the winding 1 under test, and the b-end of the auxiliary winding 2 is connected to the b-end of the winding 1 under test. Figure 3 The impedance measured by the impedance measuring instrument 3 is the total leakage impedance Z of the tested winding and the auxiliary winding. Aa Its expression is

[0034] The total leakage impedance Z of the tested winding and the auxiliary winding Aa The expression contains three unknown parameters: c, ω r ξ, this unknown parameter can be obtained through the total leakage impedance Z. Aa The frequency response curve was obtained by fitting. Figure 4 In a certain embodiment, the total leakage impedance Z Aa The frequency response curve is measured, and ω can be obtained by fitting this curve. r The actual values ​​of ξ.

[0035] according to Figure 4 Curve fitting yields ω r And the actual value of ξ, the coefficient K can be calculated. c The actual value of the measured winding leakage impedance Z is then... AW With error coefficient K c The real part of the ratio is the actual value of the AC resistance of the measured winding 1.

[0036] Based on the above specific implementation steps Figure 5 The present invention provides the following steps for measuring the AC resistance of the winding: measuring the leakage impedance Z of the winding under test. AW The total leakage impedance Z of the tested winding and the auxiliary winding was measured. Aa The frequency response curve; based on the total leakage impedance Z of the tested winding and the auxiliary winding. AaThe total leakage impedance Z was obtained by fitting the frequency response curve. Aa The characteristic parameter ω r and ξ; based on the characteristic parameter ω r The error coefficient K is calculated from the fitted value of ξ. c ; Calculate the AC resistance of the winding being tested.

[0037] The above embodiments are merely illustrative of the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solutions based on the technical concept proposed in this invention shall fall within the scope of protection of this invention.

Claims

1. A method for measuring and correcting the AC resistance of a high-frequency magnetic component winding, comprising setting an auxiliary winding in the high-frequency magnetic component, and considering the influence of the coupling capacitance between the auxiliary winding and the winding under test to correct the AC resistance value of the winding under test; characterized in that, The method includes the following steps: Step 1: Measure the leakage impedance of the winding under test; The expression for the leakage impedance of the measured winding is: With AW =K c (r1+jωl1) Among them, Z AW K represents the leakage impedance of the winding under test. c The error coefficient, c is the equivalent coupling capacitance between the measured winding and the auxiliary winding, r1 and r2 are the AC resistances of the measured winding and the auxiliary winding, respectively, l1 and l2 are the leakage inductances of the measured winding and the auxiliary winding, respectively, and ω is the measurement frequency. r ξ are characteristic parameters, and j is the imaginary unit; Step 2: Measure and obtain the frequency characteristic curve of the total leakage impedance of the tested winding and the auxiliary winding; The expression for the total leakage impedance of the measured winding and the auxiliary winding is: Among them, Z Aa The total leakage impedance of the tested winding and the auxiliary winding; Step 3: Based on the frequency characteristic curve fitting in Step 2, obtain the characteristic parameters in the total leakage impedance of the tested winding and the auxiliary winding. Step 4: Calculate the error coefficient based on the characteristic parameters; Step 5: Calculate the AC resistance of the winding under test based on the leakage impedance and error coefficient of the winding under test.

2. The method for measuring and correcting the AC resistance of a high-frequency magnetic element winding according to claim 1, characterized in that, In step 1, the leakage impedance of the winding under test is measured by an impedance measuring instrument. The low-potential interface of the current excitation branch and the voltage measurement reference ground interface of the impedance measuring instrument are connected to the same end of the winding under test. The voltage measurement point interface of the impedance measuring instrument is connected to one end of the auxiliary winding. The other ends of the winding under test and the auxiliary winding are shorted to each other and connected to the high-potential interface of the current excitation branch of the impedance measuring instrument. The ends of the winding under test and the auxiliary winding that are shorted to each other are the same-name ends.

3. The method for measuring and correcting the AC resistance of high-frequency magnetic component windings according to claim 1, characterized in that, The measurement circuit required for calculating the error coefficient in step 4 is as follows: the low-potential interface of the current excitation branch and the voltage measurement reference ground interface of the impedance measuring instrument are connected to the same end of the winding under test; the voltage measurement point interface and the high-potential interface of the current excitation branch of the impedance measuring instrument are connected to the same end of the auxiliary winding; the other ends of the winding under test and the auxiliary winding are short-circuited to each other; and the ends of the winding under test and the auxiliary winding that are short-circuited to each other are the same-name ends.

4. The method for measuring and correcting the AC resistance of a high-frequency magnetic element winding according to claim 1, characterized in that, The AC resistance of the winding under test mentioned in step 5 is the real part of the ratio of the leakage impedance of the winding under test to the error coefficient.

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