Device, method and system for measuring equivalent series inductance of DC support capacitor

Abstract

The present invention discloses a device for measuring the equivalent series inductance of a DC link capacitor, comprising: a power supply, a DC link capacitor, a first high-voltage switch, a second high-voltage switch, a voltage measuring device, and a current recorder. Also disclosed is a method and system for measuring the equivalent series inductance of a DC link capacitor, the method comprising: charging the DC link capacitor using a power supply until a first preset voltage threshold is reached; discharging the DC link capacitor to a second preset voltage threshold, and simultaneously measuring the discharge voltage and discharge current of the DC link capacitor using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data; and determining the equivalent series inductance of the DC link capacitor based on the discharge voltage data and discharge current data. The present invention can solve the current problem of being unable to accurately test and measure the equivalent series inductance of a DC link capacitor, and can accurately and efficiently determine the equivalent series inductance.

Description

Technical Field

[0001] The present invention relates to the field of power detection technology, and more particularly to a device, method and system for measuring the equivalent series inductance of a DC support capacitor. Background Art

[0002] With the increasing emphasis on environmental protection, renewable energy sources such as wind and photovoltaic power are becoming increasingly important in national energy development strategies. To meet the needs of renewable energy development and provide high-quality, stable electricity, the development of flexible DC transmission technology is imperative. With advantages such as harmonic suppression, reduced reactive power compensation capacity, and no commutation failure, flexible DC transmission technology represents a new development trend in power transmission and distribution technology.

[0003] DC support capacitors, also known as DC-link capacitors, are used in flexible DC transmission systems primarily to absorb the high-amplitude pulsating current drawn from the inverter to the DC-link, preventing the high-amplitude pulsating voltage generated across the DC-link impedance. This keeps the inverter's power supply voltage fluctuation within an acceptable range. They also prevent voltage overshoots and transient overvoltages from the DC-link from affecting the inverter. In recent years, high-voltage self-healing capacitors using metallized film have gained widespread adoption in DC-link applications due to their superior electrical performance.

[0004] The DC support capacitor is composed of a capacitor core, a shell, a sleeve, a copper foil lead, an insulating potting compound (such as polyurethane) and other accessories. The capacitor core is composed of a number of components, and the component is the core unit of the capacitor. The capacitor element is made of a metallized polypropylene film of a certain thickness and number of layers wound around a polycarbonate insulating core rod, and the metallized film is formed by attaching a nanometer-thick metal electrode to a dielectric film by vacuum evaporation. The gold spraying process is used at the end of the component to realize the lead-out of the capacitor electrode, such as Figure 1 As shown, multiple capacitor elements are connected in series or in parallel by welding copper foil leads to form the entire capacitor core.

[0005] The main difference between DC support capacitors and conventional full-film capacitors is that their electrodes are very thin, and the thin metallized electrodes give them self-healing properties. High-voltage self-healing capacitors use organic thin films as energy storage media. Since the film inevitably has defects or impurities during the production process, the dielectric strength of these areas is lower than that of the surrounding areas. These areas are called electrical weak points. As the external applied voltage increases, the film at the electrical weak point will first break down, forming a short circuit point. Other intact components connected in parallel with the faulty component and the energy stored in the faulty component itself will discharge through the breakdown point, forming a discharge channel. Since the electrodes of high-voltage self-healing capacitors are very thin, the short-circuit breakdown current causes local high temperatures, causing the thin metal layer at the breakdown point to evaporate rapidly, diffuse outward, and restore the insulation. Therefore, local breakdown will not affect the entire capacitor. This process is called "self-healing". Figure 2 As shown in the figure, after successful self-healing, the capacitor can continue to operate reliably. The self-healing characteristics of high-voltage self-healing capacitors largely prevent capacitor failure caused by a single weak point, significantly extending the service life of the capacitor.

[0006] In DC link capacitor design, equivalent series inductance (ESI) is a critical technical specification, closely related to the capacitor element's structure, material composition, and component layout. Minimum ESI is crucial for the excellent performance of high-voltage self-healing capacitors. Because the ESI of DC link capacitors is extremely small, direct measurement is difficult. Therefore, current DC link capacitor testing typically uses a resonant sweep frequency meter to measure the ESI. However, errors caused by instrument wiring cannot be verified during testing, which can lead to deviations between the ESI and the true value. Summary of the Invention

[0007] The present invention provides a device, method and system for measuring the equivalent series inductance of a DC support capacitor, so as to solve the problem of how to measure the equivalent series inductance of a DC support capacitor.

[0008] In order to solve the above problem, according to one aspect of the present invention, a device for measuring the equivalent series inductance of a DC link capacitor is provided, characterized in that the device comprises: a power supply, a DC link capacitor, a first high-voltage switch, a second high-voltage switch, a voltage measuring device, and a current recorder; wherein,

[0009] The positive electrode of the power supply is connected to one end of the first high-voltage switch, the other end of the first high-voltage switch is respectively connected to the positive electrode of the DC link capacitor and one end of the second high-voltage switch, and the other end of the DC link capacitor is respectively connected to the other end of the second high-voltage switch and the negative electrode of the voltage; the current recorder is connected in series in a loop including the DC link capacitor and the second high-voltage switch, and the voltage measuring device is connected in parallel to both ends of the DC link capacitor;

[0010] The power supply is used to apply voltage to the DC support capacitor to charge the DC support capacitor;

[0011] The voltage measuring device is used to measure the discharge voltage and obtain discharge voltage data when the DC support capacitor is discharged;

[0012] The current recorder is used to measure the discharge current and obtain discharge current data when the DC support capacitor is discharged.

[0013] Preferably, the power supply is a DC charging power supply.

[0014] According to another aspect of the present invention, a method for measuring the equivalent series inductance of a DC link capacitor is provided, the method comprising:

[0015] Using a power supply to charge the DC support capacitor until a first preset voltage threshold is reached;

[0016] The DC support capacitor is discharged to a second preset voltage threshold, and a discharge voltage and a discharge current of the DC support capacitor are measured using a voltage measuring device and a current tester respectively to obtain discharge voltage data and discharge current data;

[0017] The equivalent series inductance of the DC link capacitor is determined according to the discharge voltage data and the discharge current data.

[0018] Preferably, the method further comprises:

[0019] Before charging the DC support capacitor, the first high-voltage switch is controlled to be in a combined state and the second high-voltage switch is controlled to be in a disconnected state, and after charging is completed, the first high-voltage switch is controlled to be in a disconnected state.

[0020] Preferably, the method further comprises:

[0021] Before the DC support capacitor is discharged, the first high-voltage switch is controlled to be in an open state and the second high-voltage switch is controlled to be in a closed state.

[0022] Preferably, determining the equivalent series inductance of the DC link capacitor according to the discharge voltage and the discharge current includes:

[0023] measuring a current waveform of the discharge current and a voltage waveform of the discharge voltage;

[0024] An equivalent series inductance of the DC link capacitor is determined based on the current waveform and the voltage waveform.

[0025] Preferably, determining the equivalent series inductance of the DC link capacitor based on the current waveform and the voltage waveform includes:

[0026] Based on the current waveform, obtaining an oscillation period, a first peak value, and a second peak value of the current;

[0027] Based on the voltage waveform, obtaining a charging voltage and a discharging start voltage;

[0028] Calculating a total voltage of the DC link capacitor based on the oscillation period, the first peak value, and the second peak value;

[0029] An equivalent series inductance of the DC link capacitor is calculated based on the total voltage, the charging voltage, and the discharge start voltage.

[0030] Preferably, based on the oscillation period, the first peak value and the second peak value, the total voltage of the DC link capacitor is calculated according to the following formula:

[0031]

[0032] Wherein, L is the total voltage; T is the oscillation period, I1 is the first peak value, and I2 is the second peak value.

[0033] Preferably, based on the total voltage, the charging voltage and the discharge start voltage, the equivalent series inductance of the DC link capacitor is calculated according to the following formula:

[0034]

[0035] Wherein, Ls is the equivalent series inductance of the DC support capacitor; U1 and U2 are the charging voltage and the discharge starting voltage respectively obtained according to the discharge voltage data.

[0036] Preferably, the first preset voltage threshold is determined according to the rated voltage of the DC link capacitor; and the second preset voltage threshold is 0.

[0037] According to another aspect of the present invention, a system for measuring the equivalent series inductance of a DC link capacitor is provided, the system comprising:

[0038] a charging unit, configured to charge the DC support capacitor using a power supply until a first preset voltage threshold is reached;

[0039] a discharge unit, configured to discharge the DC support capacitor to a second preset voltage threshold, and simultaneously measure a discharge voltage and a discharge current of the DC support capacitor during discharge using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data;

[0040] An equivalent series inductance determination unit is used to determine the equivalent series inductance of the DC link capacitor according to the discharge voltage data and the discharge current data.

[0041] The present invention provides a device for measuring the equivalent series inductance of a DC support capacitor, comprising: a power supply, a DC support capacitor, a first high-voltage switch, a second high-voltage switch, a voltage measuring device, and a current recorder. The present invention also provides a method and system for measuring the equivalent series inductance of a DC support capacitor, comprising: charging the DC support capacitor using a power supply until a first preset voltage threshold is reached; discharging the DC support capacitor to a second preset voltage threshold, and simultaneously measuring the discharge voltage and discharge current of the DC support capacitor using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data; and determining the equivalent series inductance of the DC support capacitor based on the discharge voltage data and discharge current data. The present invention solves the current problem of being unable to accurately test and measure the equivalent series inductance of a DC support capacitor, and can accurately and efficiently determine the equivalent series inductance. The present invention can be used to verify the design value of the equivalent series inductance of a DC support capacitor, thereby improving and optimizing design parameters and enhancing the operational reliability of the DC support capacitor. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] A more complete understanding of exemplary embodiments of the present invention may be obtained by referring to the following drawings:

[0043] Figure 1 This is a structural diagram of a high-voltage self-healing capacitor element;

[0044] Figure 2 Schematic diagram of self-healing of high-voltage self-healing capacitor;

[0045] Figure 3 Schematic diagram of the structure of a device 300 for measuring the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention;

[0046] Figure 4 Schematic diagram of the measurement of the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention;

[0047] Figure 5Flowchart of a method 500 for measuring the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention;

[0048] Figure 6 FIG. 6 is a schematic structural diagram of a system 600 for measuring the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0049] Exemplary embodiments of the present invention will now be described with reference to the accompanying drawings. However, the present invention may be embodied in many different forms and is not limited to the embodiments described herein. These embodiments are provided to provide a thorough and complete disclosure of the present invention and to fully convey the scope of the present invention to those skilled in the art. The terminology used in the exemplary embodiments shown in the accompanying drawings is not intended to limit the present invention. In the accompanying drawings, identical elements are denoted by the same reference numerals.

[0050] Unless otherwise specified, the terms used herein (including technical terms) have the meanings commonly understood by those skilled in the art. In addition, it is understood that terms defined in commonly used dictionaries should be understood to have the same meanings as those in the context of the relevant fields, and should not be understood as idealized or overly formal meanings.

[0051] As described in the background, equivalent series inductance (ESI) is a crucial technical specification in DC link capacitor design. It's closely related to the capacitor's element structure, material composition, and component layout. Minimum ESI is crucial for high-voltage self-healing capacitors to achieve excellent performance. Because the ESI of DC link capacitors is extremely small, direct measurement is difficult. Therefore, current DC link capacitor testing typically uses a resonant sweep frequency meter to measure the ESI. However, errors caused by instrument wiring cannot be verified during testing, which can lead to deviations between the ESI and the true value.

[0052] To address the above issues, embodiments of the present invention provide a device and method for measuring the equivalent series inductance of a DC link capacitor. This method utilizes a power supply to charge the DC link capacitor until a first preset voltage threshold is reached. The DC link capacitor is then discharged to a second preset voltage threshold. A voltage measuring device and a current tester are then used to simultaneously measure the discharge voltage and current of the DC link capacitor, obtaining discharge voltage and discharge current data. Based on the discharge voltage and discharge current data, the equivalent series inductance of the DC link capacitor is determined. This invention addresses the current difficulty in accurately measuring the equivalent series inductance of a DC link capacitor, enabling accurate and efficient determination of the equivalent series inductance. This solution is described in detail below.

[0053] Figure 3 FIG. 3 is a schematic structural diagram of a device 300 for measuring the equivalent series inductance of a DC support capacitor according to an embodiment of the present invention. Figure 3 As shown, an embodiment of the present invention provides a device 300 for measuring the equivalent series inductance of a DC link capacitor, comprising: a power supply 301, a DC link capacitor 302, a first high-voltage switch 303, a second high-voltage switch 304, a voltage measuring device 305, and a current recorder 306. The positive electrode of the power supply is connected to one end of the first high-voltage switch, the other end of the first high-voltage switch is respectively connected to the positive electrode of the DC link capacitor and one end of the second high-voltage switch, and the other end of the DC link capacitor is respectively connected to the other end of the second high-voltage switch and the negative electrode of the voltage; the current recorder is connected in parallel to a loop including the DC link capacitor and the second high-voltage switch, and the voltage measuring device is connected in parallel to both ends of the DC link capacitor.

[0054] Preferably, the power supply 301 is used to apply voltage to the DC support capacitor to charge the DC support capacitor.

[0055] Preferably, the power supply 301 is a DC charging power supply.

[0056] Preferably, the voltage measuring device 305 is used to measure the discharge voltage and obtain discharge voltage data when the DC support capacitor is discharging.

[0057] Preferably, the current recorder 306 is used to measure the discharge current and obtain discharge current data when the DC support capacitor is discharging.

[0058] The solution of the present invention is: using a power supply to apply a certain voltage to the DC link capacitor to charge it, and then causing the tested DC link capacitor to discharge through a gap as short as possible between the terminals. By measuring the waveforms of the discharge voltage and current and performing calculations, the equivalent series inductance of the DC link capacitor can be obtained.

[0059] In an embodiment of the present invention, a DC charging power supply applies voltage to the DC link capacitor to charge the DC link capacitor, and then discharges the DC link capacitor. During discharge, a voltage measuring device is used to measure the discharge voltage and obtain discharge voltage data, while a current recorder is used to measure the discharge current and obtain discharge current data. Prior to charging the DC link capacitor, the first high-voltage switch is controlled to be in a combined state and the second high-voltage switch is controlled to be in a disconnected state. After charging is complete, the first high-voltage switch is controlled to be in a disconnected state. Prior to discharging the DC link capacitor, the first high-voltage switch is controlled to be in a disconnected state and the second high-voltage switch is controlled to be in a closed state.

[0060] In the embodiments of the present invention, the discharge gap of the DC link capacitor is minimized to reduce the external loop inductance to the same order of magnitude as the capacitor's equivalent series inductance. The resistance of the entire discharge loop is minimized to ensure underdamped discharge and a resonant oscillating discharge current waveform. The voltage measurement equipment must be sufficiently accurate to detect any sudden voltage drop at the start of discharge.

[0061] Figure 4 FIG. 1 is a schematic diagram showing the principle of measuring the equivalent series inductance of a DC support capacitor according to an embodiment of the present invention. Figure 4 As shown, the measurement device includes: a DC charging power supply 1, a DC link capacitor 2, a first high-voltage switch 3, a second high-voltage switch 4, a voltage measuring device 5, and a current recorder 6. To ensure that the discharge of the DC link capacitor 2 can generate an oscillating waveform, the gap of the second high-voltage switch 4 should be as small as possible to reduce external resistance.

[0062] The specific test process is as follows: S1, close the first high-voltage switch 3, open the second high-voltage switch 4, and use the DC charging power supply 1 to charge the DC support capacitor 2 until the voltage across the DC support capacitor reaches 0.1 ～ The charging is completed when the voltage reaches 1 times the rated voltage, and the first high-voltage switch 3 is disconnected after the charging is completed; S2, the first high-voltage switch 3 is disconnected, the second high-voltage switch 4 is closed, and the DC link capacitor 2 is discharged through the test circuit until the voltage on the DC link capacitor 2 drops to 0. At the same time, during the discharge process, the discharge voltage u(t) and the discharge current i1(t) waveforms are recorded respectively by the voltage measuring device 5 and the current recorder 6; S3, the equivalent series capacitance is determined according to the waveforms of the discharge voltage u(t) and the current i1(t).

[0063] Figure 5 FIG. 5 is a flow chart of a method 500 for measuring the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention. Figure 5 As shown, the method 500 for measuring the equivalent series inductance of a DC link capacitor provided in an embodiment of the present invention includes:

[0064] Step 501: Using a power supply to charge a DC link capacitor until a first preset voltage threshold is reached;

[0065] Preferably, the method further comprises:

[0066] Before charging the DC support capacitor, the first high-voltage switch is controlled to be in a combined state and the second high-voltage switch is controlled to be in a disconnected state, and after charging is completed, the first high-voltage switch is controlled to be in a disconnected state.

[0067] In step 502 , the DC link capacitor is discharged to a second preset voltage threshold, and a discharge voltage and a discharge current of the DC link capacitor are measured using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data.

[0068] Preferably, the method further comprises:

[0069] Before the DC support capacitor is discharged, the first high-voltage switch is controlled to be in an open state and the second high-voltage switch is controlled to be in a closed state.

[0070] Preferably, the first preset voltage threshold is determined according to the rated voltage of the DC link capacitor; and the second preset voltage threshold is 0.

[0071] Step 503: Determine the equivalent series inductance of the DC link capacitor according to the discharge voltage data and the discharge current data.

[0072] Preferably, determining the equivalent series inductance of the DC link capacitor according to the discharge voltage and the discharge current includes:

[0073] measuring a current waveform of the discharge current and a voltage waveform of the discharge voltage;

[0074] An equivalent series inductance of the DC link capacitor is determined based on the current waveform and the voltage waveform.

[0075] Preferably, determining the equivalent series inductance of the DC link capacitor based on the current waveform and the voltage waveform includes:

[0076] Based on the current waveform, obtaining an oscillation period, a first peak value, and a second peak value of the current;

[0077] Based on the voltage waveform, obtaining a charging voltage and a discharging start voltage;

[0078] Calculating a total voltage of the DC link capacitor based on the oscillation period, the first peak value, and the second peak value;

[0079] An equivalent series inductance of the DC link capacitor is calculated based on the total voltage, the charging voltage, and the discharge start voltage.

[0080] Preferably, based on the oscillation period, the first peak value and the second peak value, the total voltage of the DC link capacitor is calculated according to the following formula:

[0081]

[0082] Wherein, L is the total voltage; T is the oscillation period, I1 is the first peak value, and I2 is the second peak value.

[0083] Preferably, based on the total voltage, the charging voltage and the discharge start voltage, the equivalent series inductance of the DC link capacitor is calculated according to the following formula:

[0084]

[0085] Wherein, Ls is the equivalent series inductance of the DC support capacitor; U1 and U2 are the charging voltage and the discharge starting voltage respectively obtained according to the discharge voltage data.

[0086] In an embodiment of the present invention, the device 300 for measuring the equivalent series inductance of a DC support capacitor as described above is used to record the discharge voltage u(t) and current i1(t) waveforms through a voltage tester 5 and a current recorder 6 during the discharge process, which will not be described in detail here.

[0087] After obtaining the discharge voltage and discharge current, the oscillation period T, the first peak value I1, and the second peak value I2 of the current can be obtained from the waveform of the discharge current. From this, the total voltage L of the discharge circuit can be obtained as

[0088]

[0089] From the sudden drop in the discharge voltage waveform at the start of discharge, we can obtain the charging voltage U1 and the discharge start voltage U2. Therefore, the equivalent series inductance Ls of the DC link capacitor is:

[0090]

[0091] Wherein, Ls is the equivalent series inductance of the DC support capacitor; L is the total voltage; U1 and U2 are the charging voltage and discharge start voltage respectively obtained according to the discharge voltage data; T, I1 and I2 are the discharge period, first peak value and second peak value respectively obtained according to the discharge current signal.

[0092] The equivalent series inductance of the DC link capacitor 2 can be obtained by the above method.

[0093] The method of the present invention applies a certain voltage to the capacitor through a power supply to charge it, then discharges the tested DC support capacitor through a gap as short as possible between the terminals. By measuring the waveforms of the discharge voltage and current, the equivalent series inductance of the DC support capacitor can be obtained. This solves the current problem of being unable to accurately test and measure the equivalent series inductance of the DC support capacitor, and can accurately and efficiently determine the equivalent series inductance. The present invention can be used to verify the design value of the equivalent series inductance of the DC support capacitor, so as to improve and optimize the design parameters and enhance the operational reliability of the DC support capacitor.

[0094] Figure 6 FIG. 6 is a schematic structural diagram of a system 600 for measuring the equivalent series inductance of a DC link capacitor according to an embodiment of the present invention. Figure 6 As shown, a system 600 for measuring the equivalent series inductance of a DC link capacitor provided in an embodiment of the present invention includes: a charging unit 601 , a discharging unit 602 and an equivalent series inductance determining unit 603 .

[0095] Preferably, the charging unit 601 is used to charge the DC support capacitor using a power supply until a first preset voltage threshold is reached;

[0096] Preferably, the system further comprises:

[0097] The setting unit is configured to: before charging the DC support capacitor, control the first high-voltage switch to be in a combined state and the second high-voltage switch to be in a disconnected state, and control the first high-voltage switch to be in a disconnected state after charging is completed.

[0098] Preferably, the discharge unit 602 is used to discharge the DC support capacitor to a second preset voltage threshold, and simultaneously measure the discharge voltage and discharge current of the DC support capacitor during discharge using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data.

[0099] Preferably, the system further comprises:

[0100] The setting unit is configured to control the first high-voltage switch to be in an open state and the second high-voltage switch to be in a closed state before the DC support capacitor is discharged.

[0101] Preferably, the equivalent series inductance determining unit 603 is configured to determine the equivalent series inductance of the DC link capacitor according to the discharge voltage data and the discharge current data.

[0102] Preferably, the equivalent series inductance determining unit 603 determines the equivalent series inductance of the DC link capacitor according to the discharge voltage and the discharge current, including:

[0103]

[0104]

[0105] Wherein, Ls is the equivalent series inductance of the DC support capacitor; L is the total voltage; U1 and U2 are the charging voltage and discharge start voltage respectively obtained according to the discharge voltage data; T, I1 and I2 are the discharge period, first peak value and second peak value respectively obtained according to the discharge current signal.

[0106] Preferably, the first preset voltage threshold is determined according to the rated voltage of the DC link capacitor; and the second preset voltage threshold is 0.

[0107] The measurement system 600 for the equivalent series inductance of a DC link capacitor according to the embodiment of the present invention corresponds to the measurement system 500 for the equivalent series inductance of a DC link capacitor according to another embodiment of the present invention, and will not be described in detail herein.

[0108] The invention has been described above with reference to a few embodiments. However, it is readily apparent to a person skilled in the art that other embodiments than the ones disclosed above are equally within the scope of the invention, as defined by the appended patent claims.

[0109] Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to "a / the [means, component, etc.]" are to be interpreted openly as referring to at least one instance of the means, component, etc., unless explicitly stated otherwise. The steps of any method disclosed herein do not necessarily need to be performed in the exact order disclosed, unless explicitly stated otherwise.

[0110] Those skilled in the art will appreciate that the embodiments of the present application can be provided as methods, systems, or computer program products. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment in combination with software and hardware. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to magnetic disk storage, CD-ROM, optical storage, etc.) that contain computer-usable program code.

[0111] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to produce a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the steps in the process. Figure 1 a process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0112] These computer program instructions may also be stored in a computer readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 a process or multiple processes and / or boxes Figure 1 The function specified in one or more boxes.

[0113] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operational steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing the instructions executed on the computer or other programmable device for implementing the process. Figure 1 a process or multiple processes and / or boxes Figure 1 The steps for the function specified in one or more boxes.

[0114] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific implementation methods of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A device for measuring the equivalent series inductance of a DC link capacitor, characterized in that: The device includes: a power supply, a DC support capacitor, a first high-voltage switch, a second high-voltage switch, a voltage measuring device and a current recorder; wherein, The positive electrode of the power supply is connected to one end of the first high-voltage switch, the other end of the first high-voltage switch is respectively connected to the positive electrode of the DC link capacitor and one end of the second high-voltage switch, and the other end of the DC link capacitor is respectively connected to the other end of the second high-voltage switch and the negative electrode of the power supply; the current recorder is connected in series in a loop including the DC link capacitor and the second high-voltage switch, and the voltage measuring device is connected in parallel to both ends of the DC link capacitor; The power supply is used to apply voltage to the DC support capacitor to charge the DC support capacitor; The voltage measuring device is used to measure the discharge voltage and obtain discharge voltage data when the DC support capacitor is discharged; The current recorder is used to measure the discharge current and obtain discharge current data when the DC support capacitor is discharged.

2. The device according to claim 1, characterized in that The power supply is a DC charging power supply.

3. A method for measuring the equivalent series inductance of a DC link capacitor, characterized in that: The device for measuring the equivalent series inductance of a DC link capacitor according to claim 1, wherein the method comprises: Using a power supply to charge the DC support capacitor until a first preset voltage threshold is reached; The DC support capacitor is discharged to a second preset voltage threshold, and a discharge voltage and a discharge current of the DC support capacitor are measured using a voltage measuring device and a current tester respectively to obtain discharge voltage data and discharge current data; The equivalent series inductance of the DC link capacitor is determined according to the discharge voltage data and the discharge current data.

4. The method according to claim 3, characterized in that The method further comprises: Before charging the DC support capacitor, the first high-voltage switch is controlled to be in a combined state and the second high-voltage switch is controlled to be in a disconnected state, and after charging is completed, the first high-voltage switch is controlled to be in a disconnected state.

5. The method according to claim 3, characterized in that The method further comprises: Before the DC support capacitor is discharged, the first high-voltage switch is controlled to be in an open state and the second high-voltage switch is controlled to be in a closed state.

6. The method according to claim 3, characterized in that The determining of the equivalent series inductance of the DC link capacitor according to the discharge voltage and the discharge current includes: measuring a current waveform of the discharge current and a voltage waveform of the discharge voltage; An equivalent series inductance of the DC link capacitor is determined based on the current waveform and the voltage waveform.

7. The method according to claim 6, characterized in that Determining the equivalent series inductance of the DC link capacitor based on the current waveform and the voltage waveform includes: Based on the current waveform, obtaining an oscillation period, a first peak value, and a second peak value of the current; Based on the voltage waveform, obtaining a charging voltage and a discharging start voltage; Calculating a total inductance of the DC link capacitor based on the oscillation period, the first peak value, and the second peak value; An equivalent series inductance of the DC link capacitor is calculated based on the total inductance, the charging voltage, and the discharge start voltage.

8. The method according to claim 7, characterized in that Based on the oscillation period, the first peak value, and the second peak value, the total inductance of the DC link capacitor is calculated according to the following formula: Wherein, L is the total inductance; T is the oscillation period, I1 is the first peak value, I2 is the second peak value; and C is the capacitance value of the DC support capacitor.

9. The method according to claim 7, characterized in that Based on the total inductance, the charging voltage, and the discharge start voltage, the equivalent series inductance of the DC link capacitor is calculated according to the following formula: Wherein, Ls is the equivalent series inductance of the DC support capacitor; U1 and U2 are the charging voltage and the discharge starting voltage respectively obtained according to the discharge voltage data; and L is the total inductance.

10. The method according to claim 3, characterized in that The first preset voltage threshold is determined according to the rated voltage of the DC link capacitor; the second preset voltage threshold is 0.

11. A system for measuring the equivalent series inductance of a DC link capacitor, characterized in that: The system comprises: a charging unit, configured to charge the DC support capacitor using a power supply until a first preset voltage threshold is reached; a discharge unit, configured to discharge the DC support capacitor to a second preset voltage threshold, and simultaneously measure a discharge voltage and a discharge current of the DC support capacitor during discharge using a voltage measuring device and a current tester, respectively, to obtain discharge voltage data and discharge current data; An equivalent series inductance determination unit is used to determine the equivalent series inductance of the DC link capacitor according to the discharge voltage data and the discharge current data.

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