A core loss measurement system and method based on switched oscillation

Abstract

The application relates to a kind of core loss measurement systems and methods based on switch oscillation, the system includes: adjustable DC power supply: parallel in the two ends of DC capacitor, for charging DC capacitor;DC capacitor: provide energy for core loss test;To-be-measured magnetic element: parallel in the two ends of DC capacitor;Frequency modulation capacitor: parallel in the two ends of to-be-measured magnetic element, for adjusting the target frequency of core loss test;Switch: first switch is installed between DC capacitor and adjustable DC power supply, for controlling DC capacitor charging;Second switch is installed between DC capacitor and to-be-measured magnetic element, for exciting high-frequency oscillation;Signal acquisition module: measure the current flowing through to-be-measured magnetic element and the voltage across frequency modulation capacitor;Core loss calculation module: to the inductance current, capacitor voltage obtained by measurement are calculated and handled, obtain core loss data and draw core loss density curve.Compared with prior art, the application has the advantages of high precision, simple and efficient.

Description

Technical Field

[0001] This invention relates to the field of magnetic core loss measurement technology, and in particular to a magnetic core loss measurement system and method based on switching oscillation. Background Technology

[0002] The trend towards miniaturization and high-frequency development of power electronic power converters has placed higher demands on the power density and efficiency of power devices. The core loss of magnetic components is an important part of the power converter loss. Therefore, accurate measurement of core loss is of great significance for the design and operation of power converter systems.

[0003] Existing methods for measuring magnetic core loss can be broadly categorized into two types: thermal methods and electrical methods. The basic idea of ​​thermal methods is to obtain the loss by measuring the temperature change caused by core loss within a hot chamber. Electrical methods typically employ a two-winding method, calculating core loss by measuring the voltage and current of the magnetic element under a sinusoidal voltage injection condition. To improve accuracy, the two-winding method often adds an external tuning capacitor to measure core loss under resonant conditions.

[0004] Comparing existing core loss measurement techniques reveals that: the thermal method offers high accuracy but requires a high-performance thermal chamber, is complex to operate, and has a long measurement time; the dual-winding method is simple to implement, but core loss measurement errors can occur due to phase differences in voltage and electrical measurements. Especially for high-frequency cores, measurement errors caused by phase differences are often significant. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-precision, simple and efficient magnetic core loss measurement system and method based on switching oscillation.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] According to a first aspect of the present invention, a core loss measurement system based on switching oscillation is provided, the system comprising:

[0008] Adjustable DC power supply: connected in parallel across the DC capacitor to charge the DC capacitor;

[0009] DC capacitor: Provides energy for core loss testing;

[0010] The magnetic component under test is connected in parallel across the DC capacitor.

[0011] Frequency modulation capacitor: Connected in parallel across the magnetic component under test, used to adjust the target frequency for core loss testing;

[0012] Switch: a first switch K1 is installed between the direct current capacitor and the adjustable direct current power supply, for controlling the charging of the direct current capacitor; a second switch K2 is installed between the direct current capacitor and the magnetic element to be measured, for exciting high-frequency oscillation;

[0013] Signal acquisition module: using a current probe to measure the current i flowing through the magnetic element to be measured L , and using a voltage probe to measure the voltage u across the frequency-modulated capacitor C ;

[0014] Magnetic core loss calculation module: calculating and processing the measured inductance current and capacitor voltage to obtain magnetic core loss data and draw a magnetic core loss density curve.

[0015] Preferably, the frequency-modulated capacitor is a low-loss frequency-modulated capacitor.

[0016] Preferably, the magnetic element to be measured is an inductor or a transformer.

[0017] Preferably, the magnetic core loss density curve is a curve of the relationship between the magnetic core loss density and the magnetic flux density amplitude, wherein the magnetic core loss density is the magnetic core loss per unit volume.

[0018] According to a second aspect of the present application, a method using the above-mentioned magnetic core loss measurement system based on switch oscillation is provided, which comprises the following steps:

[0019] Step S1, charging of the direct current capacitor: the first switch K1 is closed, the second switch K2 is opened, and the adjustable direct current power supply is adjusted to charge the direct current capacitor to U0;

[0020] Step S2, charging of the magnetic element to be measured: after the first switch K1 is opened, the second switch K2 is closed, and after t0, the second switch K2 is turned off;

[0021] Step S3, oscillation test: measuring the current i flowing through the magnetic element to be measured L and the voltage u across the frequency-modulated capacitor C ;

[0022] Step S4, data processing: calculating the magnetic core loss density and drawing a curve.

[0023] Preferably, the step S4 is specifically:

[0024] Selecting two adjacent periods to calculate a point on the magnetic core loss density curve;

[0025] Selecting a plurality of points on the magnetic core loss density curve in sequence according to time, and fitting to obtain the magnetic core loss density curve.

[0026] Preferably, according to the voltage current oscillation waveform, the magnetic core loss density corresponding to the i-th point in the magnetic core loss density curve and the magnetic flux density calculation formula is:

[0027]

[0028]

[0029] Wherein U peak_i , U peak_i+1 are the i-th and i+1-th peak values in the voltage oscillation; I peak_i , I peak_i+1 are the values of the current oscillation envelope corresponding to the time of U peak_i and U peak_i+1 ; V is the magnetic core volume; N is the number of turns of the magnetic element to be measured; A is the cross-sectional area of the magnetic core to be measured; ω is the oscillation angular frequency; P core_loss_i is the magnetic core loss density of the i-th point in the magnetic core loss density curve.

[0030] According to a third aspect of the present application, an electronic device is provided, comprising a memory and a processor, the memory having a computer program stored thereon, and the processor implementing any of the methods when executing the program.

[0031] According to a fourth aspect of the present application, a computer readable storage medium is provided, having a computer program stored thereon, and the program being executed by a processor to implement any of the methods.

[0032] Compared with the prior art, the present application has the following advantages:

[0033] 1) High precision: the commonly used double winding method in current engineering cannot eliminate the magnetic core loss measurement error caused by the difference between voltage and current measurement (such as the difference in probe delay time) ; especially in the high frequency band, the influence of the difference between voltage and current measurement is great; the present application calculates the magnetic core loss by measuring the voltage and current peak values, and there is no measurement difference problem;

[0034] 2) Simple and efficient: the measurement circuit structure is simple, no high-end expensive equipment is needed, and multiple points on the magnetic core loss density curve can be obtained at one time. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 is a schematic diagram of a magnetic core loss measurement system structure;

[0036] Figure 2 is a flowchart of a magnetic core loss measurement method;

[0037] Figure 3 is a schematic diagram of oscillation voltage and current waveforms;

[0038] Figure 4For double-winding method system diagram;

[0039] Figure 5 For test results under 300 kHz;

[0040] Figure 6 For test results under 200 kHz. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work should fall within the protection scope of the present application.

[0042] EMBODIMENT

[0043] The present embodiment gives a magnetic core loss measurement system based on switching oscillation, as shown in the figure, the system comprises: Figure 1

[0044] Adjustable DC power supply: connected in parallel across the DC capacitor, used to charge the DC capacitor.

[0045] DC capacitor: provides energy for the magnetic core loss test; in the actual system, a large-capacity electrolytic capacitor can be used.

[0046] The magnetic element to be tested: connected in parallel across the DC capacitor; in the actual system, the magnetic element to be tested can be an inductor or a transformer, connected in parallel across the DC capacitor.

[0047] Frequency adjustment capacitor: connected in parallel across the magnetic element to be tested, used to adjust the target frequency of the magnetic core loss test; in the actual system, the frequency adjustment capacitor is selected from a capacitor with a small equivalent series resistance, such as a thin-film capacitor, a ceramic capacitor, a mica capacitor, and a low-loss frequency adjustment capacitor.

[0048] Switch: the first switch K1 is installed between the DC capacitor and the adjustable DC power supply, used to control the charging of the DC capacitor; the second switch K2 is installed between the DC capacitor and the magnetic element to be tested, used to excite high-frequency oscillation;

[0049] Signal acquisition module: uses a current probe to measure the current i flowing through the magnetic element to be tested L , and uses a voltage probe to measure the voltage u across the frequency adjustment capacitor C ;

[0050] ​Core loss calculation module: This module processes the measured inductor current and capacitor voltage to obtain core loss data and plot the core loss density curve. The core loss density curve represents the relationship between core loss density and magnetic flux density, where core loss density is the core loss per unit volume.

[0051] Next, a method for measuring core loss using the aforementioned switching oscillation-based magnetic core loss measurement system is presented, such as... Figure 2 As shown, the method includes the following steps:

[0052] Step S1: DC capacitor charging: Close the first switch K1 and open the second switch K2. Adjust the adjustable DC power supply to charge the DC capacitor to U0.

[0053] Step S2, Charging the magnetic component under test: After disconnecting the first switch K1, close the second switch K2, wait for t0, and then turn off the second switch K2;

[0054] Step S3, Oscillation Test: Measure the current i flowing through the magnetic component under test. L With the voltage u across the frequency modulation capacitor C ;

[0055] Step S4, Data Processing: Calculate the core loss density and plot the curve, specifically:

[0056] according to Figure 2 The measurement steps, and the schematic diagram of the voltage and current waveforms that generate high-frequency oscillations after the second switch K2 is turned off are shown below. Figure 3 As shown. Select two adjacent cycles and calculate a point on the core loss density curve;

[0057] By sequentially selecting two adjacent periods in time, points on multiple core loss density curves are obtained, and the core loss density curve is obtained by fitting.

[0058] Based on the voltage and current oscillation waveforms, the formulas for calculating the core loss density and flux density amplitudes corresponding to the i-th point in the core loss density curve are as follows:

[0059]

[0060]

[0061] U peak_i U peak_i+1 These are the i-th and i+1-th peak values ​​in the voltage oscillation, respectively; I peak_i I peak_i+1 U peak_i with U peak_i+1 The value of the current oscillation envelope at time t; V is the core volume; N is the number of turns of the magnetic element under test; A is the cross-sectional area of ​​the core under test; ω is the oscillation angular frequency; Pcore_loss_i is the core loss density of the i-th point in the core loss density curve.

[0062] The main parameters of the system in this embodiment are shown in Table 1 below, and the magnetic element to be measured is an inductor element. The frequency modulation capacitance values are set to 1940 PF and 4620 PF respectively. According to the steps of the application, the current probe and the voltage probe are used to obtain the oscillation current and voltage signals with oscillation frequencies of 300 kHz and 200 kHz respectively; and then the results obtained according to the formulas (1) and (2) are used to draw the core loss density curve. Figure 2

[0063] Table 1 Test system parameters

[0064]

[0065] Double-winding method: The system diagram of the double-winding method is shown in Figure 2, which is composed of a signal generator, a power amplifier, a magnetic element to be measured, a tuning capacitor, a signal acquisition module and a calculation module. The signal generator frequencies are set to 300 kHz and 200 kHz respectively, and the amplitudes are set to V j1 and V j2 , and the waveforms are sine waves. The tuning capacitor values are set to 1940 PF and 4620 PF respectively. The inductor current and the power amplifier output voltage are measured. The core loss density and the corresponding magnetic flux density amplitude are obtained by the voltage and current data, and a point on the core loss density curve is obtained. By changing the signal generator output voltage amplitude, different points can be obtained. The test results are shown in Figures 3 and 4. Figure 4 Figure 5 Figure 6

[0066] The electronic device of the application includes a central processing unit (CPU) which can perform various appropriate actions and processes according to computer program instructions stored in a read-only memory (ROM) or loaded into a random access memory (RAM) from a storage unit. In the RAM, various programs and data required for device operation can also be stored. The CPU, the ROM and the RAM are connected to each other through a bus. An input / output (I / O) interface is also connected to the bus.

[0067] A plurality of components in the device are connected to the I / O interface, including: an input unit such as a keyboard, a mouse, etc.; an output unit such as various types of displays, a loudspeaker, etc.; a storage unit such as a magnetic disk, an optical disk, etc.; and a communication unit such as a network card, a modem, a wireless communication transceiver, etc. The communication unit allows the device to exchange information / data with other devices through a computer network such as the Internet and / or various telecommunication networks.

[0068] ​​​​The processing units perform the various methods and processes described above, such as methods S1-S4. For example, in some embodiments, methods S1-S4 can be implemented as a computer software program tangibly embodied in a machine readable medium, such as a storage unit. In some embodiments, portions or all of the computer program can be loaded and / or installed onto the device via the ROM and / or the communication unit. When the computer program is loaded onto the RAM and executed by the CPU, one or more of the steps of methods S1-S4 described above can be performed. Alternatively, in other embodiments, the CPU can be configured to perform methods S1-S4 by any other suitable means, such as by way of firmware.

[0069] The functionality described above in this document can be performed, at least in part, by one or more hardware logic components. For example, and without limitation, illustrative types of hardware logic components that can be used include Field-programmable Gate Arrays (FPGAs), Application-specific Integrated Circuits (ASICs), Application-specific Standard Products (ASSPs), System-on-a-chip systems (SOCs), Complex Programmable Logic Devices (CPLDs), etc.

[0070] Program code for carrying out the methods of the present application can be written in any combination of one or more programming languages. This program code can be provided to a processor or controller of a general purpose computer, special purpose computer, or other programmable data processing apparatus to produce a machine, such that the program code, when executed by the processor or controller, causes the machine to perform the functions / acts specified in the flowcharts and / or block diagrams. The program code can be executed entirely on a machine, partially on a machine, partially on a machine and partially on a remote machine or entirely on a remote machine or server.

[0071] In the context of the present application, a machine-readable medium can be a tangible medium that can contain or store program for use by or in connection with an instruction execution system, apparatus, or device. The machine-readable medium can be a machine-readable signal medium or a machine-readable storage medium. Machine-readable storage media can include, without limitation, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination of the foregoing. More specific examples of machine-readable storage media can include one or more lines of a system, a portable computer diskette, a hard disk, a random access memory (RAM), a read-only memory (ROM), an erasable programmable read-only memory (EPROM or Flash memory), an optical fiber, a portable compact disc read-only memory (CD-ROM), an optical storage device, a magnetic storage device, or any suitable combination of the foregoing.

[0072] The above merely illustrates the specific embodiments of the present application, but the protection scope of the present application is not limited thereto, and any skilled person in the art can easily think of various equivalent modifications or replacements within the technical range disclosed by the present application, and these modifications or replacements shall be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A method of employing a magnetic core loss measurement system based on switched oscillation, characterized by, The system comprises: An adjustable DC power supply connected in parallel across the DC capacitor for charging the DC capacitor; A DC capacitor for providing energy for the magnetic core loss test; A magnetic element under test connected in parallel across the DC capacitor; A frequency-adjusting capacitor connected in parallel across the magnetic element under test for adjusting the target frequency of the magnetic core loss test; A switch, the first switch K1 being installed between the DC capacitor and the adjustable DC power supply for controlling the charging of the DC capacitor, and the second switch K2 being installed between the DC capacitor and the magnetic element under test for exciting high-frequency oscillation; Signal acquisition module: use current probe to measure the current through the magnetic element to be measured i L , using a voltage probe to measure the voltage across the frequency modulation capacitor u C ; A magnetic core loss calculation module for calculating and processing the measured inductance current and capacitor voltage to obtain the magnetic core loss data and draw the magnetic core loss density curve; The method comprises the following steps: Step S1, DC capacitor charging: the first switch K1 is closed, the second switch K2 is opened, and the adjustable DC power source charges the DC capacitor to U 0; Step S2, charging the magnetic element under test: after the first switch K1 is opened, the second switch K2 is closed, and after t0, the second switch K2 is turned off; Step S3, oscillation test: measuring the current flowing through the magnetic element under test i L with the frequency-modulated voltage across the capacitor u C ; Step S4, data processing: calculating the magnetic core loss density and drawing the curve; According to the voltage and current oscillation waveform, the formula for calculating the magnetic core loss density and the magnetic flux density amplitude corresponding to the point in the magnetic core loss density curve is: i ​ （1） （2） wherein U peak_i , U peak_i+1 are the values of the current oscillation envelope at the moments i and i +1 peak value respectively in the voltage oscillation; I peak_i , I peak_i+1 are the values of the current oscillation envelope at the moments U peak_i and U peak_i+1 respectively; V is the magnetic core volume; N is the number of turns of the magnetic element to be measured; A is the cross-sectional area of the magnetic core to be measured; is the oscillation angular frequency; P core_loss_i is the magnetic core loss density at the point i of the magnetic core loss density curve.

2. The method of claim 1, wherein, The frequency-adjusting capacitor is a low-loss frequency-adjusting capacitor.

3. The method of claim 1, wherein, The magnetic element under test is an inductor or a transformer.

4. The method of claim 1, wherein, The magnetic core loss density curve is the curve of the magnetic core loss density versus the magnetic flux density amplitude, wherein the magnetic core loss density is the magnetic core loss per unit volume.

5. The method of claim 1, wherein, The step S4 is specifically: Selecting two adjacent periods to calculate a point on the magnetic core loss density curve; Selecting points on the magnetic core loss density curve in sequence according to time to fit the magnetic core loss density curve. 6.An electronic device comprising a memory and a processor, the memory having stored thereon a computer program, characterized in that, The processor executes the program to implement the method of any one of claims 1-5.

7. A computer readable storage medium having stored thereon a computer program, characterized in that, The program is executed by the processor to implement the method of any one of claims 1-5.

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