An inductance and parasitic parameter integrated measurement system and method

Abstract

The application discloses an inductance and parasitic parameter integrated measurement system and method. The driving circuit, the signal conditioning circuit and the display screen in the system are connected with the control unit, the output end of the second operational amplifier is connected with the control unit, the inverting input end of the second operational amplifier is connected with the output end of the first operational amplifier and one end of the sampling resistor, the gate of the field effect switch tube is connected with the driving circuit, the source of the field effect switch tube is connected with the inverting input end of the first operational amplifier and the other end of the sampling resistor, the drain of the field effect switch tube is connected with the signal conditioning circuit and the measured inductance, the signal conditioning circuit is further connected with the measured inductance, and the power module supplies power for the system. The inductance measurement calculation and the parasitic capacitance and resistance measurement calculation are naturally separated, so that the main parameter (inductance value) and the parasitic parameter (parasitic capacitance and resistance) of the measured inductance can be accurately obtained through one measurement, and the measurement efficiency is greatly improved.

Description

Technical Field

[0001] This invention relates to the field of electronic measurement technology, and more specifically, to an integrated measurement system and method for inductance and parasitic parameters. Background Technology

[0002] In fields such as switching power supplies, inductors and transformers are key energy conversion components. In practical applications, inductors and transformers are not ideal components. Besides their inherent inductive parameters, the parasitic capacitance and resistance of their windings also determine the circuit's efficiency, noise, and other characteristics. Therefore, accurate and rapid measurement of both the inductive and parasitic parameters of inductor or transformer windings is crucial for component manufacturing, circuit design, production quality control, and fault diagnosis. Currently, the measurement of inductor parameters generally relies on impedance analyzers or LCR meters. However, existing measurement techniques and methods have significant limitations: First, while conventional instruments can accurately measure the equivalent impedance or L and Q values ​​at specific frequencies, they cannot directly and simultaneously calculate all the parameters constituting its electrical behavior. Engineers need to perform multiple measurements at different frequency points and estimate parasitic capacitance and loss resistance by manually calculating or curve fitting using complex formulas based on the changing trends of the impedance curve. This process is cumbersome and prone to human error. Secondly, in order to gain a comprehensive understanding of the inductor parameters, users must frequently switch modes, scan frequencies, and process subsequent data. The entire process has a low degree of automation and low measurement efficiency, making it difficult to meet the needs of rapid and batch inspection in industrial production.

[0003] Therefore, there is an urgent need in the field for a measurement scheme that can automatically, synchronously and accurately extract complete equivalent circuit model parameters, including ideal inductance, parasitic capacitance and loss resistance, through a single rapid measurement operation, in order to overcome the technical bottlenecks of low measurement efficiency, incomplete model and cumbersome operation in the prior art. Summary of the Invention

[0004] The purpose of this invention is to provide an integrated measurement system and method for inductance and parasitic parameters, so as to overcome the defects of the prior art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: An integrated measurement system for inductance and parasitic parameters includes a power supply module, a control unit, a drive circuit, a field-effect transistor, a sampling resistor, a first operational amplifier, a second operational amplifier, a signal conditioning circuit, and a display screen. The driving circuit, signal conditioning circuit, and display screen are all connected to the control unit. The output terminal of the second operational amplifier is connected to the control unit. The inverting input terminal of the second operational amplifier is connected to the output terminal of the first operational amplifier and one end of the sampling resistor. The gate of the field-effect transistor is connected to the driving circuit. The source of the field-effect transistor is connected to the inverting input terminal of the first operational amplifier and the other end of the sampling resistor. The drain of the field-effect transistor is connected to the signal conditioning circuit and the inductor under test. The signal conditioning circuit is also connected to the inductor under test. The power supply module supplies power to the system.

[0006] Furthermore, it also includes a capacitor connected to the power module, with the other end of the capacitor grounded.

[0007] Furthermore, it also includes a first resistor connected between the output terminal and the inverting input terminal of the second operational amplifier, and a second resistor connected between the inverting input terminal of the second operational amplifier and the output terminal of the first operational amplifier.

[0008] The present invention also provides a measurement method based on the above-described integrated inductance and parasitic parameter measurement system, comprising the following steps: S1. Turn on the power module, the control unit enters the working state and queries and reads the touch keys on the touch screen; S2. Connect the inductor to be measured to the inductance measurement terminal; S3. Press the test start button, and the control unit reads the level change of the test start bit and enters the test control program; S4. The control unit outputs an excitation pulse wave to the drive circuit. After being amplified by the drive circuit, it drives the gate of the field-effect switch. The sampling resistor converts the current change into a voltage change and sends it to the ADC1 of the control unit for analog-to-digital conversion. The inductance value of the inductor under test is calculated according to the inductance calculation formula. S5. When the falling edge of the excitation pulse wave arrives, the field-effect switch is turned off. The flyback voltage waveform generated by the inductor under test is processed by the signal conditioning circuit and then sent to the ADC2 of the control unit for analog-to-digital conversion to obtain the voltage amplitude and period data of the overshoot and oscillation waveform. The values ​​of parasitic capacitance and resistance are calculated based on the series equivalent model of the inductor and the principle of series resonance.

[0009] Compared with the prior art, the advantages of the present invention are: the measurement system of the present invention naturally separates the inductance measurement calculation from the parasitic capacitance and resistance measurement calculation, so that the main parameters (inductance value) and parasitic parameters (parasitic capacitance and resistance) of the inductor under test can be accurately obtained in a single measurement, thereby greatly improving the measurement efficiency. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0011] Figure 1 This is a circuit diagram of the integrated inductance and parasitic parameter measurement system of the present invention; Figure 2 This is a schematic diagram of the parasitic parameter characteristics in this invention; Figure 3 This is a schematic diagram of the resonant circuit formed during flyback in this invention and its impedance characteristics; Figure 4 This is a schematic diagram of the waveforms of the inductance measurement system in this invention when the switch is turned on and the inductor is charged. Figure 5 This is a schematic diagram of the voltage waveform of the inductor flyback overshoot oscillation when the switch is turned off in the inductance measurement system of this invention; Figure 6 This is a flowchart of the integrated measurement method for inductance and parasitic parameters in this invention. Detailed Implementation

[0012] The preferred embodiments of the present invention will now be described in detail with reference to the accompanying drawings, so that the advantages and features of the present invention can be more easily understood by those skilled in the art, thereby providing a clearer and more explicit definition of the scope of protection of the present invention.

[0013] See Figure 1 As shown, this embodiment discloses an integrated measurement system for inductance and parasitic parameters, including a power supply module 110, a control unit 120, a drive circuit 124, a field-effect transistor 141, a sampling resistor 142, a first operational amplifier 143, a second operational amplifier 144, a signal conditioning circuit 125, and a display screen 130; the drive circuit 124, the signal conditioning circuit 125, and the display screen 130 are all connected to the control unit 120, and the output terminal of the second operational amplifier 144 is connected to the control unit 120. The inverting input of the operational amplifier 144 is connected to the output of the first operational amplifier 143 and one end of the sampling resistor 142. The gate of the field-effect transistor 141 is connected to the driving circuit 124. The source of the field-effect transistor 141 is connected to the inverting input of the first operational amplifier 143 and the other end of the sampling resistor 142. The drain of the field-effect transistor 141 is connected to the signal conditioning circuit 125 and the inductor under test 202. The signal conditioning circuit 125 is also connected to the inductor under test 202. The power supply module 110 supplies power to the system.

[0014] In this embodiment, in addition to supplying power to the various circuits of the test system, the power module 110 also outputs a DC voltage. The excitation pulse wave is applied to the terminals of the inductor 202 under test. The control unit 120 realizes functions such as excitation pulse wave output, ADC acquisition, peripheral communication interface (connected to touch screen, LCD display, etc.), data calculation and processing; the drive circuit 124 receives the excitation pulse wave output by the control unit 120, amplifies it and drives the field-effect switch 141; the field-effect switch 141 is the main working element in the main circuit of the inductor 202 under test, realizing the on and off control of the main circuit of the inductor; the sampling resistor 142 is used to sample the current of the main circuit of the inductor; the first operational amplifier 143 realizes the level clamping of the source of the field-effect switch 141; the second operational amplifier 144 realizes the voltage inversion amplification of the current sampling voltage; the LCD touch screen 130 is used to input operation information, such as start test, save data, read back data, etc., and also to display the parameter information of the inductor under test and the equipment working status information.

[0015] This embodiment also includes a capacitor 111 connected to the power module 110, with the other end of the capacitor 111 grounded.

[0016] This embodiment also includes a first resistor 146 connected between the output terminal and the inverting input terminal of the second operational amplifier 144, and a second resistor 145 connected between the inverting input terminal of the second operational amplifier 144 and the output terminal of the first operational amplifier 143.

[0017] See Figure 2 The figure shows a schematic diagram of the parasitic parameter characteristics of the transformer winding. The inductance of the 201 winding of the transformer under test can be equivalent to an inductance L (202), a parasitic resistance R (203), and a parasitic capacitance C (204).

[0018] See Figure 3 The figure shows a schematic diagram of the resonant circuit and its impedance characteristics formed when the transformer winding operates in flyback mode. From Figure 3 As can be seen, in the flyback mode, the inductor (201) can be equivalently represented by the series connection of inductor L (202), parasitic resistance R (202), and parasitic capacitance C (203). The impedance-frequency characteristic curve of this equivalent circuit is shown in Figure 204. Figure 3 As shown in b. Figure 3 In b, f0 is the resonant frequency.

[0019] See Figure 4 In the figure u L i is the voltage applied across the inductor. L U is the current in the inductor. Rs For resistors The voltage on the power supply. When the rising edge of the excitation pulse arrives, the gate level of the field-effect switch 141 jumps from low to high, the field-effect switch 141 turns on, and the power supply voltage V... D2 The entire current is applied across the inductor 202 under test, causing the current in the inductor 202 to increase linearly. The current sampling resistor... After the current change is converted into a voltage change by the second operational amplifier 144, it is amplified by inversion and sent to the ADC1 (121) of the control unit 120 for analog-to-digital conversion. When the falling edge of the excitation pulse wave arrives, the gate level of the field-effect switch 141 jumps from high level to low level, and the field-effect switch 141 is turned off. Let the pulse width of the excitation pulse wave be... Current sampling resistor The voltage on (142) is According to Faraday's law of electromagnetic induction, the formula for calculating inductance can be expressed as:

[0020] Control unit 120 according to Substituting the data after analog-to-digital conversion into the calculation, we obtain the main parameter of the inductor 202 under test: the inductance value.

[0021] Because the first operational amplifier 143 clamps the source level of the field-effect switch 141 to ground, the power supply voltage V D2 The entire voltage is applied across the inductor 202 under test, meaning the voltage applied across the inductor 202 is precisely known; on the other hand, because of the current sampling resistor... (142) It is not connected in series in the circuit from the inductor 202 under test to ground, therefore the current sampling resistor (142) It has no effect on the voltage drop across the inductor 202 being measured, thus allowing the current sampling resistor to be used. The value of (142) should be appropriately increased. For these two reasons, the measurement accuracy of the inductor 202 under test can be greatly improved.

[0022] See Figure 5 As shown, when the falling edge of the excitation pulse wave arrives, the gate level of the field-effect switch 141 jumps from high level to low level, the field-effect switch 141 is turned off, and the current path of the inductor under test 202 through the field-effect switch 141 is suddenly interrupted. As a result, the inductor under test 202 generates a flyback voltage through the signal conditioning circuit 125, and its waveform is characterized by overshoot and oscillation. Figure 5 The waveform diagram of flyback voltage oscillation is shown below. Figure 5As can be seen, the flyback voltage exhibits a periodic oscillation waveform after overshoot, with one oscillation period occurring between two adjacent peaks, as shown in the figure between peaks 401b and 401c. Furthermore, the oscillation amplitude gradually decreases exponentially according to the decay time constant. The flyback oscillation voltage is processed by the signal conditioning circuit 125 and sent to the control unit ADC2 for analog-to-digital conversion, obtaining data such as the voltage amplitude, frequency, and decay time of the overshoot and oscillation waveforms. Based on the inductance value calculated in the previous step, and according to the resonance principle of inductance, its parasitic capacitance, and resistance, the formula for calculating the parasitic capacitance can be expressed as:

[0023] The parasitic resistance can be obtained from the ring-down time formula.

[0024] Because the measurement system naturally separates the inductance measurement calculation from the parasitic capacitance and resistance measurement calculation, it can accurately determine the main parameters (inductance value) and parasitic parameters (parasitic capacitance and resistance) of the inductor in a single measurement. This significantly improves measurement efficiency compared to traditional measurement methods.

[0025] See Figure 6 As shown, the present invention also provides a measurement method based on the above-described integrated inductance and parasitic parameter measurement system, comprising the following steps: Step S1: Turn on the power module 110. The control unit 120 enters the working state and queries and reads the touch keys on the touch screen. The touch keys on the LCD touch screen 130 interface include the "Test" key, "Stop" key, "Save" key, "Read Back" key, etc. Step S2: Connect the inductor to be measured to the inductance measurement input terminal; Step S3: Press the test button on the touch screen. The control unit 120 reads the level change of the test start bit and enters the test control program. Step S4: The control unit 120 outputs an excitation pulse wave to the drive circuit 124. After being amplified by the drive circuit 124, the drive circuit 124 drives the gate of the field effect switch 141. The sampling resistor 142 converts the current change into a voltage change and sends it to the ADC1 of the control unit 120 for analog-to-digital conversion. The inductance value of the inductor under test is calculated according to the inductance calculation formula. Step S5: When the falling edge of the excitation pulse wave arrives, the field-effect switch 141 is turned off. The flyback voltage waveform generated by the inductor under test 202 is processed by the signal conditioning circuit 125 and then sent to the ADC2 of the control unit 120 for analog-to-digital conversion to obtain the voltage amplitude and period data of the overshoot and oscillation waveform. The values ​​of parasitic capacitance and resistance are calculated based on the series equivalent model of the inductor and the principle of series resonance.

[0026] Unlike traditional methods for measuring inductance parameters (inductance value, parasitic capacitance, and parasitic resistance), the measurement system of this invention naturally separates the inductance measurement calculation from the parasitic capacitance and resistance measurement calculation. This allows for the accurate determination of the main parameters (inductance value) and parasitic parameters (parasitic capacitance and resistance) of the inductor under test in a single measurement, thereby greatly improving the measurement efficiency.

[0027] Although embodiments of the present invention have been described in conjunction with the accompanying drawings, the patent owner may make various modifications or alterations within the scope of the appended claims, as long as they do not exceed the protection scope described in the claims of the present invention, they shall be within the protection scope of the present invention.

Claims

1. An integrated measurement system for inductance and parasitic parameters, characterized in that, It includes a power module (110), a control unit (120), a drive circuit (124), a field-effect transistor (141), a sampling resistor (142), a first operational amplifier (143), a second operational amplifier (144), a signal conditioning circuit (125), and a display screen (130). The driving circuit (124), signal conditioning circuit (125), and display screen (130) are all connected to the control unit (120). The output terminal of the second operational amplifier (144) is connected to the control unit (120). The inverting input terminal of the second operational amplifier (144) is connected to the output terminal of the first operational amplifier (143) and one end of the sampling resistor (142). The gate of the field-effect switch (141) is connected to the driving circuit (124). The source of the field-effect switch (141) is connected to the inverting input terminal of the first operational amplifier (143) and the other end of the sampling resistor (142). The drain of the field-effect switch (141) is connected to the signal conditioning circuit (125) and the inductor under test (202). The signal conditioning circuit (125) is also connected to the inductor under test (202). The power supply module (110) supplies power to the system.

2. The integrated measurement system for inductance and parasitic parameters according to claim 1, characterized in that, It also includes a capacitor (111) connected to the power module (110), with the other end of the capacitor (111) grounded.

3. The integrated measurement system for inductance and parasitic parameters according to claim 1, characterized in that, It also includes a first resistor (146) connected between the output terminal and the inverting input terminal of the second operational amplifier (144) and a second resistor (145) connected between the inverting input terminal of the second operational amplifier (144) and the output terminal of the first operational amplifier (143).

4. A measurement method for an integrated inductance and parasitic parameter measurement system according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Power module (110) is turned on, control unit (120) enters working state and queries and reads the touch keys of the display screen; S2. Connect the inductor to be measured to the inductance measurement terminal; S3. Press the test start button on the display screen. The control unit (120) reads the level change of the test start bit and enters the test control program. S4. The control unit (120) outputs an excitation pulse wave to the drive circuit (124). After being amplified by the drive circuit (124), the drive circuit (124) drives the gate of the field effect switch (141). The sampling resistor (142) converts the current change into a voltage change and sends it to the ADC1 of the control unit (120) for analog-to-digital conversion. The inductance value of the inductor under test is calculated according to the inductance calculation formula. S5. When the falling edge of the excitation pulse wave arrives, the field effect switch (141) is turned off. The flyback voltage waveform generated by the inductor under test (202) is processed by the signal conditioning circuit (125) and sent to the ADC2 of the control unit (120) for analog-to-digital conversion to obtain the voltage amplitude and period data of the overshoot and oscillation waveform. The values ​​of parasitic capacitance and resistance are calculated according to the series equivalent model of the inductor and the principle of series resonance.

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