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Thin-film capacitor ESL extraction method based on switching transient frequency information

A film capacitor and frequency information technology, applied in the direction of instruments, measuring electricity, measuring electrical variables, etc., can solve the problems of difficult to measure ESL, high cost, high peak value, etc., achieve simple and convenient measurement and data processing process, and avoid potential safety hazards , the effect of low current level

Active Publication Date: 2021-03-02
ZHEJIANG UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The patent with the publication number CN108646098A is based on the ESL measurement method in the standard JB / T8168-1999, and proposes an experimental method for detecting the internal ESL of the self-healing metallized film capacitor; this measurement method has certain shortcomings and limitations: ( 1) The oscillating current is excited by the body of the film capacitor, and the peak value of the discharge current is as high as kA. The test conditions are relatively dangerous, and it is difficult to measure the ESL of the film capacitor at the end of the life cycle; (2) It is difficult to completely eliminate the additional inductance of the measurement circuit. Short-circuit experiments avoid errors, and the additional stray inductance introduced by the short-circuit connectors used is still difficult to determine; (3) The test equipment includes high-range current transformers and capacitor discharge circuits, resulting in relatively bulky test platforms and relatively high costs

Method used

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  • Thin-film capacitor ESL extraction method based on switching transient frequency information
  • Thin-film capacitor ESL extraction method based on switching transient frequency information
  • Thin-film capacitor ESL extraction method based on switching transient frequency information

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Embodiment 1

[0022] Embodiment 1: a kind of thin film capacitor ESL extraction method based on switching transient frequency information, carry out according to the following steps:

[0023] a. Build a silicon carbide MOSFET double pulse test platform; figure 1 As shown, the silicon carbide MOSFET double-pulse test platform includes a capacitor to be tested, a stacked busbar, a silicon carbide Schottky barrier diode and a silicon carbide MOSFET in series in sequence, and the two ends of the silicon carbide Schottky barrier diode are connected in parallel. Load inductance, the capacitor under test is expressed as C t , the silicon carbide Schottky barrier diode is denoted as D, the silicon carbide MOSFET is denoted as S, and the load capacitance is denoted as L load ; Wherein, the capacitor to be tested is used as the bus capacitance of the silicon carbide MOSFET double-pulse test platform, embedded in the laminated busbar with known parasitic parameters; the geometric structure of the lam...

Embodiment 2

[0033] Embodiment 2: On the basis of embodiment 1, as a specific embodiment, two metallized film capacitors, old and new, are selected as capacitors to be tested, wherein the new film capacitor is represented as C tN with L ESLN The equivalent series model of the old film capacitor is denoted as C tO with L ESLO equivalent series model.

[0034] Taking the turn-off transient voltage of SiC MOSFET in the double-pulse test platform as an example, when the new film capacitor is used as the bus capacitance, the turn-off voltage waveform of SiC MOSFET is recorded as V ds1 , when the old film capacitor is used as the bus capacitor, the turn-off voltage waveform is recorded as V ds2 ;V ds1 waveform like figure 2 As shown, V ds2 waveform like Figure 4 shown.

[0035] According to the measured turn-off voltage waveform, respectively for V ds1 and V ds2 Do a fast Fourier transform. V ds1 The spectrogram of image 3 As shown, V ds2 The frequency graph of Figure 5 shown....

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Abstract

The invention discloses a thin-film capacitor ESL extraction method based on switching transient frequency information. The method comprises the following steps: a, building a silicon carbide MOSFET double-pulse test platform, wherein the capacitor to be tested serves as a bus capacitor of the silicon carbide MOSFET double-pulse test platform and is embedded into a laminated busbar with known parasitic parameters; b, measuring the voltage waveform of the silicon carbide MOSFET in a switching-on or switching-off transient state, and extracting the voltage under-damping oscillation frequency excited by a loop between the capacitor to be measured and the parasitic capacitor of the laminated busbar by using Fourier transform; and c, calculating the internal ESL of the capacitor to be measuredaccording to the measured voltage under-damping oscillation frequency. The silicon carbide MOSFET double-pulse test platform built in the invention has the advantages of low cost and miniaturization,avoids large-current oscillation of the capacitor body in the extraction process of the ESL, does not need an additional short-circuit test, and has relatively high test safety.

Description

technical field [0001] The invention relates to the technical field of power electronics testing, in particular to a film capacitor ESL extraction method based on switching transient frequency information. Background technique [0002] Compared with electrolytic capacitors, metallized film capacitors have a longer service life and higher reliability in long-term operation. As DC bus support capacitors, they are widely used in large-capacity power electronic devices such as flexible DC transmission and traffic traction systems. Limited by the production process, the equivalent series inductance (ESL) inside the film capacitor cannot be ignored. As one of the main components of the stray inductance of the capacitor-power device commutation circuit, it increases the switching transient voltage of the power device. Overshoot and loss restrict the design margin of the converter; in addition, the internal ESL of the film capacitor increases the resonance risk of the stray inductan...

Claims

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Application Information

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IPC IPC(8): G01R27/26G01R31/00G01R23/16
CPCG01R23/16G01R27/26G01R31/00
Inventor 胡斯登王明阳梁梓鹏何湘宁
Owner ZHEJIANG UNIV
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