CN-122017363-A - Capacitance measuring circuit and measuring method of micro-method electrolytic capacitor of sound box main board

CN122017363ACN 122017363 ACN122017363 ACN 122017363ACN-122017363-A

Abstract

The invention discloses and provides a capacitance measuring circuit and a capacitance measuring method for a micro-farad electrolytic capacitor of a sound box main board, which have the advantages of simple structure, low cost, wide applicability and high measuring efficiency. The invention comprises a programmable direct current power supply module, a relay, a current sampling resistor, an operational amplifier for instruments, an ADC voltage acquisition module and a main control module, wherein the programmable direct current power supply module is connected with the relay, the relay is connected with the current sampling resistor, the current sampling resistor is connected with the anode of a micro-farad electrolytic capacitor of a sound box main board, the programmable direct current power supply module is connected with the micro-farad electrolytic capacitor of the sound box main board, the operational amplifier for instruments is connected with two ends of the current sampling resistor, the operational amplifier for instruments is connected with the ADC voltage acquisition module, and the main control module is respectively connected with the ADC voltage acquisition module, the programmable direct current power supply module and the control end of the relay. The current change data of the charging process is obtained by using a sampling resistor, and an electronic load module is not needed. The invention is applied to the technical field of capacitance measurement of electrolytic capacitors.

Inventors

SU JUNHUA
XU BOWEN
ZHANG SHUYING

Assignees

珠海市运泰利自动化设备有限公司

Dates

Publication Date: 20260512
Application Date: 20260121

Claims (5)

1. A capacitance measuring circuit of a micro-method electrolytic capacitor of a sound box main board is characterized by comprising a programmable direct current power supply module (DC), a relay (S), a current sampling resistor (R), an operational amplifier (U) for an instrument, an ADC voltage acquisition module (ADC) and a master control Module (MCU), wherein the positive electrode of the programmable direct current power supply module (DC) is connected with the input end of the relay (S), the output end of the relay (S) is connected with one end of the current sampling resistor (R), the other end of the current sampling resistor (R) is connected with the positive electrode of the micro-method electrolytic capacitor (C) of the sound box main board, the negative electrode of the programmable direct current power supply module (DC) is connected with the negative electrode of the micro-method electrolytic capacitor (C) of the sound box main board, the two input ends of the operational amplifier (U) for the instrument are respectively connected with the two ends of the current sampling resistor (R), and the output end of the operational amplifier (U) for the instrument is connected with the master control end of the ADC voltage acquisition module (ADC), and the DC voltage acquisition module (ADC) for the instrument is respectively connected with the master control Module (MCU).
2. The circuit for measuring capacitance of micro-scale electrolytic capacitor of sound box main board according to claim 1, wherein the model of the operational amplifier (U) for the instrument is AD 8233 ARMZ.
3. The capacitance measuring circuit of the micro-scale electrolytic capacitor of the sound box main board of claim 1, wherein the main control Module (MCU) controls the programmable direct current power supply module (DC) through SPI and I2C buses, and the main control Module (MCU) controls the ADC voltage acquisition module (ADC) through the SPI buses, so that supply control of a power supply and acquisition of voltage data corresponding to charging current are realized.
4. The circuit for measuring capacitance of micro-farad electrolytic capacitor of sound box main board according to claim 1, wherein said main control Module (MCU) controls said relay (S) through GPIO.
5. A measuring method of capacitance measuring circuit of micro-scale electrolytic capacitor of sound box main board is characterized in that when programmable DC power supply module (DC) supplies power to micro-scale electrolytic capacitor (C) of sound box main board, voltage drop is generated on current sampling resistor (R) when current sampling resistor (R) is passed, voltage drop of resistor is collected by operational amplifier (U) for instrument, and single-ended voltage signal is transferred to ADC voltage collecting module (ADC) for data collection, and the method comprises the following steps: a. the main control Module (MCU) controls the relay (S) to be closed, and a loop is opened; b. A main control Module (MCU) controls an ADC voltage acquisition module (ADC) to start a data acquisition function, and the acquisition time is 2 seconds; c. a main control Module (MCU) controls the programmable power supply module to output 5V voltage, and at the moment, the micro-farad electrolytic capacitor (C) of the sound box main board starts to be charged; d. After the acquisition time is up, the relay (S) is disconnected, and the power supply voltage is closed; e. according to the collected voltage data of the sampling current, any two points (t 1, V1), (t 2, V2) in the current falling process are selected, and the data of the two points are substituted into a capacitance solving formula, namely C=|(t1-t2) /R*[ln(V1/V2)]|。

Description

Capacitance measuring circuit and measuring method of micro-method electrolytic capacitor of sound box main board Technical Field The invention relates to a capacitance measuring circuit and a capacitance measuring method of an electrolytic capacitor, in particular to a capacitance measuring circuit and a capacitance measuring method of a micro-scale electrolytic capacitor of a sound box main board. Background The intelligent sound box equipment is more and more popular, various functions are more and more complete, and the intelligent sound box equipment plays an increasingly important role in daily work, life and entertainment of people. Some large electrolytic capacitors, usually in the micro-method level, can be selectively placed in part of the main boards of the loudspeaker box equipment, and are usually placed on the main power supply rail of the main boards of the loudspeaker box, the work of the power amplifier chip needs a stable direct current power supply, the electrolytic capacitors play a role in filtering and stabilizing voltage, and meanwhile, high-frequency clutter in the power supply is filtered, so that the clutter is prevented from interfering the work of the power amplifier chip and other circuits, and the situations such as bottom noise, current noise and the like are prevented. In order to enable the intelligent sound box equipment to be used normally, electrolytic capacitors in the intelligent sound box equipment are required to be detected, and whether the electrolytic capacitors are normal or not is mainly detected at present. One of the existing test schemes for electrolytic capacitors is to charge the capacitor with a direct current power supply, disconnect the power supply after the charging is completed, use an electronic load module to perform constant current discharge on the capacitor, use a multimeter to measure voltage data at two ends of the capacitor, and calculate the capacitance through the obtained voltage data and constant current. The electronic load module has higher cost, complex system, needs to be configured with a discharge mode (such as constant current), parameters (current value and stop condition) and trigger logic, and also needs to calibrate current precision and verify response speed, ensures synchronization with a universal meter, greatly prolongs test preparation time and has lower test efficiency. Disclosure of Invention The invention aims to solve the technical problem of overcoming the defects of the prior art and providing a capacitance measuring circuit and a capacitance measuring method for a micro-farad electrolytic capacitor of a sound box main board, which have the advantages of simple structure, low cost, wide applicability and high measuring efficiency. The capacitance measuring circuit of the micro-farad electrolytic capacitor of the sound box main board comprises a programmable direct current power supply module DC, a relay S, a current sampling resistor R, an operational amplifier U, ADC voltage acquisition module ADC and a main control module MCU, wherein the positive electrode of the programmable direct current power supply module DC is connected with the input end of the relay S, the output end of the relay S is connected with one end of the current sampling resistor R, the other end of the current sampling resistor R is connected with the positive electrode of the micro-farad electrolytic capacitor C of the sound box main board, the negative electrode of the programmable direct current power supply module DC is connected with the negative electrode of the micro-farad electrolytic capacitor C of the sound box main board, the two input ends of the operational amplifier U are respectively connected with the two ends of the current sampling resistor R, the output end of the operational amplifier U is connected with the input end of the ADC voltage acquisition module, and the main control module MCU is respectively connected with the ADC voltage acquisition module ADC, the programmable direct current power supply module DC and the control end of the relay S. Further, the model of the operational amplifier U for the instrument is AD 8233 ARMZ. Further, the main control module MCU controls the programmable direct current power supply module DC through SPI and I2C buses, and the main control module MCU controls the ADC voltage acquisition module ADC through the SPI buses, so that supply control of a power supply and acquisition of voltage data corresponding to charging current are realized. Further, the main control module MCU controls the relay S through GPIO. The measuring method of the capacitance measuring circuit of the micro-farad electrolytic capacitor of the sound box main board comprises the following steps that when a programmable direct current power supply module DC supplies power to a micro-farad electrolytic capacitor C of the sound box main board, voltage drop is generated on a current sampling resistor R when the voltage drop