CN218331929U - Capacitor ESL measuring circuit - Google Patents

Abstract

The utility model discloses a capacitor ESL measuring circuit, which is used for measuring a capacitor to be measured and comprises a controller (1), an isolation transformer (3), a double-pulse circuit board (4) and a direct current source (2) connected with a power supply; the direct current source (2) is connected with a discharge resistor (5), a capacitor to be tested (6) and a universal meter (7) in parallel through a circuit, a first switch (8) is arranged on a connecting circuit of the direct current source (2) and the capacitor to be tested (6), and a second switch (9) is arranged on a connecting circuit of the capacitor to be tested (6) and the discharge resistor (5); the isolation transformer (3) is connected with an oscilloscope (10), the oscilloscope (10) is connected with a half-bridge circuit board (11), and the half-bridge circuit board (11) is respectively connected with the capacitor (6) to be tested and the double-pulse circuit board (4); the utility model discloses can effectively improve the measuring frequency of condenser inductance, have simultaneously and influenced little and the high characteristics of measuring accuracy by the voltage.

Description

A Capacitor ESL Measurement Circuit

technical field

The utility model relates to the field of measurement technology, in particular to a capacitor ESL measurement circuit.

Background technique

At present, the extraction methods of capacitor ESL (full name Equivalent Series Inductance, that is, equivalent series inductance) can be mainly divided into two types: short-circuit discharge method and frequency sweep of impedance analyzer. The short-circuit discharge method is difficult to eliminate the stray inductance in the test circuit, resulting in high ESL measurement results, and the oscillation frequency during the test process is low, which is an order of magnitude different from the high-frequency characteristics corresponding to the switching action of the device in the actual operating condition of the capacitor , the reference significance of the measurement results is low. At present, the solution to the above problems is to use a high-sampling rate oscilloscope or a high-precision impedance analyzer, but the high-sampling rate oscilloscope equipment has high requirements for the operating environment, and is limited by the bandwidth of the current probe and the synchronization between multiple groups of voltage and current probes; However, when a high-precision impedance analyzer performs a frequency sweep test on a capacitor, the angle, tightness, and calibration of the impedance analyzer's measurement fixture will greatly interfere with the measurement results, so the accuracy of the measurement results is not ideal.

Utility model content

The purpose of the utility model is to provide a capacitor ESL measurement circuit. The utility model can effectively increase the measurement frequency of the capacitor inductance, and has the characteristics of little voltage influence and high measurement accuracy.

The technical scheme of the utility model: a capacitor ESL measurement circuit, used to measure the capacitor to be tested, the circuit includes a controller, an isolation transformer, a double pulse circuit board and a DC source connected to the power supply; the DC source is connected in parallel through the circuit A discharge resistor, a capacitor to be tested and a multimeter are provided, a first switch is provided on the connection circuit between the DC source and the capacitor to be tested, and a second switch is provided on the connection circuit between the capacitor to be tested and the discharge resistor; the isolation transformer is connected to an oscilloscope, The oscilloscope is connected with a half-bridge circuit board, and the half-bridge circuit board is respectively connected with the capacitor to be tested and the double-pulse circuit board; the controller is connected with the oscilloscope, the DC source and the double-pulse circuit board.

In the above-mentioned capacitor ESL measurement circuit, a connection plate connected to the capacitor to be tested and the half-bridge circuit board is provided between them.

In the aforementioned capacitor ESL measurement circuit, the half-bridge circuit board is connected to the double-pulse circuit board via a cable.

In the aforementioned capacitor ESL measurement circuit, the controller is connected to the DC source and the double-pulse circuit board through a serial port line.

In the aforementioned capacitor ESL measurement circuit, the controller is connected to the oscilloscope via a network cable.

In the aforementioned capacitor ESL measurement circuit, the first switch and the second switch are air switches.

Compared with the prior art, the utility model has the following beneficial effects:

1. The utility model includes a controller, an isolation transformer, a double-pulse circuit board and a DC source connected to a power supply; the DC source is connected in parallel with a discharge resistor, a capacitor to be tested and a multimeter through a circuit, and the connection between the DC source and the capacitor to be tested is The circuit is provided with a first switch, and the connection circuit between the capacitor to be tested and the discharge resistor is provided with a second switch; the isolation transformer is connected to an oscilloscope, and the oscilloscope is connected to a half-bridge circuit board, and the half-bridge circuit board is connected to the capacitor to be tested and the discharge resistor respectively. The double-pulse circuit board is connected; the controller is connected with the oscilloscope, the DC source and the double-pulse circuit board; the first switch is closed, the DC source is turned on to charge the capacitor to be tested, and after charging is completed, the first switch is disconnected and the DC source is turned off. The controller makes the double-pulse circuit board output double-pulse signal, and the double-pulse signal reaches the half-bridge circuit board to realize level conversion, and then excites the capacitor under test and the half-bridge circuit board to generate high-frequency oscillation, and the oscilloscope captures the frequency information in the above process, etc. data and obtain the stray inductance of the capacitor to be tested; the utility model can greatly increase the measurement frequency of the inductance of the capacitor to be tested through high-frequency oscillation, and the oscillation frequency is less affected by the voltage and has good consistency. The bandwidth of the current probe and the synchronization between multiple sets of voltage and current probes reduce the number of variables involved in the calculation, thereby greatly improving the measurement accuracy and efficiency.

2. There is a connection plate connected between the capacitor to be tested and the half-bridge circuit board of the utility model, and the capacitor to be tested can be directly set on the connection plate to connect it with the half-bridge circuit board without manual operation. Line connection, effectively improving the convenience of use.

3. The first switch and the second switch of the utility model are air switches, which can protect the short circuit, severe overload and undervoltage of the circuit or electrical equipment, and effectively improve the reliability during use.

Description of drawings

Fig. 1 is the structural representation of the utility model.

The marks in the drawings are: 1-controller; 2-DC source; 3-isolation transformer; 4-double pulse circuit board; 5-discharge resistor; 6-capacitor to be tested; 7-multimeter; 8-first switch; 9-second switch; 10-oscilloscope; 11-half-bridge circuit board; 12-connection board.

detailed description

The utility model will be further described below in conjunction with the accompanying drawings and embodiments, but it is not used as a basis for limiting the utility model.

Embodiment: a kind of capacitor ESL measuring circuit, is used for measuring the capacitor under test, as shown in accompanying drawing 1, this circuit comprises controller 1, isolation transformer 3, double pulse circuit board 4 and the DC source 2 that is connected with power supply; The DC source 2 is connected with a discharge resistor 5, a capacitor to be tested 6 and a multimeter 7 in parallel through a circuit. The multimeter is used to monitor whether there is voltage at both ends of the capacitor to be tested. The connection circuit between the DC source 2 and the capacitor to be tested 6 is provided with a first A switch 8, a second switch 9 is provided on the connection circuit between the capacitor to be tested 6 and the discharge resistor 5; the isolation transformer 3 is connected with an oscilloscope 10, the oscilloscope 10 is connected with a half-bridge circuit board 11, and the isolation transformer 3 is electrically connected with the oscilloscope, The two channels of the oscilloscope are connected to the half-bridge circuit board through the sampling probe. The sampling probe obtains the voltage waveform to extract the frequency information of high-frequency oscillation. There is an ARM control board on the circuit board, which can send out double pulses with a low level of 0V and a high level of 3.3V. The level is pulled down to -4V, and the high level is pulled up to 15V, so that it can drive the SiC MOSFET on the half-bridge circuit board; switch action, thereby exciting the circuit to generate high-frequency oscillation; the controller 1 is connected with the oscilloscope 10, the DC source 2 and the double pulse circuit board 4; connected connection board 12; the half-bridge circuit board 11 is connected to the double pulse circuit board 4 through a cable; the controller 1 is connected to the DC source 2 and the double pulse circuit board 4 through a serial line; the controller 1 is connected to the double pulse circuit board 4 through The network cable is connected to the oscilloscope 10; the first switch 8 and the second switch 9 are air switches.

Working principle: Set the capacitor to be tested on the connection board with screws, close the first switch, turn on the DC source to charge the capacitor to be tested, disconnect the first switch and turn off the DC source after charging, and make the double pulse circuit board output through the controller Double pulse signal, after the double pulse signal reaches the half-bridge circuit board, it realizes level conversion, and then excites the capacitor under test and the half-bridge circuit board to generate high-frequency oscillation. The oscilloscope captures the frequency information and other data in the above process and obtains the noise of the capacitor under test For loose inductance, close the second switch to discharge the capacitor to be measured after the measurement is completed, and open the second switch after the discharge is completed.

Claims (6)

1. a capacitor ESL measuring circuit is used to measure the capacitor to be measured, and it is characterized in that: the circuit includes a controller (1), an isolation transformer (3), a double pulse circuit board (4) and a direct current source ( 2); the DC source (2) is connected in parallel with a discharge resistor (5), a capacitor under test (6) and a multimeter (7), and the DC source (2) and the capacitor under test (6) are connected on the circuit. There is a first switch (8), a second switch (9) is arranged on the connection circuit between the capacitor to be tested (6) and the discharge resistor (5); the isolation transformer (3) is connected with an oscilloscope (10), and the oscilloscope (10 ) is connected with a half-bridge circuit board (11), and the half-bridge circuit board (11) is connected with the capacitor to be tested (6) and the double pulse circuit board (4) respectively; the controller (1) is connected with the oscilloscope (10), the DC The source (2) is connected to the dual pulse circuit board (4). 2. The capacitor ESL measuring circuit according to claim 1, characterized in that: a connecting plate (12) connected to the capacitor (6) and the half-bridge circuit board (11) is provided between the capacitor to be measured (6) and the half-bridge circuit board (11). 3. The capacitor ESL measurement circuit according to claim 1, characterized in that: the half-bridge circuit board (11) is connected to the double-pulse circuit board (4) via a cable. 4. The capacitor ESL measurement circuit according to claim 1, characterized in that: the controller (1) is connected to the DC source (2) and the double-pulse circuit board (4) via a serial line. 5. The capacitor ESL measurement circuit according to claim 1, characterized in that: the controller (1) is connected to the oscilloscope (10) via a network cable. 6. The capacitor ESL measurement circuit according to claim 1, characterized in that: the first switch (8) and the second switch (9) are air switches.

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