CN-121978415-A - Online capacitance detection circuit and method for energy storage capacitor

CN121978415ACN 121978415 ACN121978415 ACN 121978415ACN-121978415-A

Abstract

The invention relates to the technical field of electronics, in particular to an online capacitance value detection circuit and method of an energy storage capacitor, wherein an undervoltage detection circuit is connected with a charging circuit, the charging circuit is connected with a discharging circuit, the discharging circuit is connected with a voltage follower circuit, the voltage follower circuit is respectively connected with a two-pole equal-proportion voltage dividing circuit and a pulse output circuit, the pulse output circuit is connected with a sampling protection circuit, and the pulse output circuit is connected with the two-pole equal-proportion voltage dividing circuit; the under-voltage detection circuit is respectively connected with the discharge circuit and the pulse generation circuit, and the pulse generation circuit is connected with the sample hold circuit. The invention has the advantages that the detection is automatically started when the power module is powered down or overhauled, the detection is directly finished through the hardware detection circuit, the on-line detection is realized without shutdown or manual intervention, and the detection is realized by adopting an analog circuit (a pulse output circuit, a two-pole same-proportion voltage division circuit, a sample hold circuit and the like).

Inventors

ZHOU MIN
SHI SHIHONG
ZHANG HAITAO
YI RONG
YU QIONG
QIU HAILONG
HAO WEIHAN
WANG JIANWU
LIU CHUNQUAN
LU TING
LIU SHENG
SU CHENG
KONG ZHIDA
GUO JINCHUAN

Assignees

中国能源建设集团广东省电力设计研究院有限公司
荣信汇科电气股份有限公司

Dates

Publication Date: 20260505
Application Date: 20260323

Claims (10)

1. The online capacitance detection circuit of the energy storage capacitor is characterized by comprising a charging circuit, a discharging circuit, a voltage following circuit, an undervoltage detection circuit, a pulse generation circuit, a two-pole equal-proportion voltage dividing circuit, a sampling and holding circuit and a pulse output circuit, wherein the input end of the undervoltage detection circuit is connected with the input end of the charging circuit, the output end of the charging circuit is connected with the input end of the discharging circuit, the output end of the discharging circuit is connected with the input end of the voltage following circuit, the output end of the voltage following circuit is respectively connected with the input end I of the two-pole equal-proportion voltage dividing circuit and the input end I of the pulse output circuit, the output end of the pulse output circuit is connected with a sampling protection circuit, and the input end II of the pulse output circuit is connected with the output end II of the two-pole equal-proportion voltage dividing circuit; The input end I of the two-pole equal-proportion voltage dividing circuit and the input end II of the two-pole equal-proportion voltage dividing circuit are connected with the sampling protection circuit, and the output end I of the two-pole equal-proportion voltage dividing circuit is connected with the sampling protection circuit; the output end of the undervoltage detection circuit is respectively connected with the output end I of the discharge circuit and the input end of the pulse generation circuit, and the output end of the pulse generation circuit is connected with the sample hold circuit.
2. The on-line capacitance detection circuit of the energy storage capacitor according to claim 1, wherein the two-pole equal-proportion voltage dividing circuit comprises a first voltage dividing circuit and a second voltage dividing circuit, the input end of the first voltage dividing circuit is respectively connected with the output end of the voltage follower circuit, the input end of the pulse output circuit and the sampling protection circuit, the output end of the first voltage dividing circuit is connected with the sampling protection circuit, the input end of the second voltage dividing circuit is connected with the sampling protection circuit, and the output end of the second voltage dividing circuit is connected with the input end of the pulse output circuit.
3. The on-line capacitance detection circuit of the energy storage capacitor according to claim 2, wherein the first voltage dividing circuit comprises a resistor R7, a resistor R8 and an operational amplifier chip IC4, the resistor R7 and the resistor R8 are connected in series, a connection point between the resistor R7 and the resistor R8 is connected with an in-phase input end of the operational amplifier chip IC4, the other end of the resistor R7 is connected with an input end of the first voltage dividing circuit, the input end of the first voltage dividing circuit is also connected with the sample and hold circuit, the other end of the resistor R8 is grounded, and an output end of the operational amplifier chip IC4 is connected with an output end of the first voltage dividing circuit; The voltage dividing circuit II comprises a resistor R9, a resistor R10 and an operational amplifier chip IC5, the resistor R9 and the resistor R10 are connected in series, a connection point between the resistor R9 and the resistor R10 is connected with the output end of the voltage dividing circuit II, the in-phase input end of the operational amplifier chip IC5 is connected with the input end of the voltage dividing circuit II, the other end of the resistor R9 is connected with the output end of the operational amplifier chip IC5, and the other end of the resistor R10 is grounded.
4. The online capacitance detection circuit of an energy storage capacitor according to claim 1, wherein the pulse output circuit comprises a resistor R11, a capacitor C4, an exclusive or gate chip IC7, a comparison chip IC6, the resistor R11 and the capacitor C4 are connected in series, a negative input end of the comparison chip IC6 is connected with an input end first of the pulse output circuit, a positive input end of the comparison chip IC6 is connected with an input end second of the pulse output circuit, an output end of the comparison chip IC6 is connected with a first input end of the exclusive or gate chip IC7, a connection point of the resistor R11 and the capacitor C4 is connected with a second input end of the exclusive or gate chip IC7, the other end of the resistor R11 is connected with a first input end of the exclusive or gate chip IC7, the other end of the capacitor C4 is grounded, and an output end of the exclusive or gate chip IC7 is connected with an output end of the pulse output circuit.
5. The on-line capacitance detection circuit of an energy storage capacitor according to claim 1, wherein the sample hold circuit comprises a comparison chip IC8, a sample hold capacitor C3 and a photoelectric isolation switch Q2, wherein an output end I of the photoelectric isolation switch Q2 is connected with an output end of a voltage dividing circuit I, an output end II of the photoelectric isolation switch Q2 is respectively connected with a negative input end of the comparison chip IC8, one end of the sample hold capacitor C3 and an input end of the voltage dividing circuit II, and a cathode of a light emitting diode of the photoelectric isolation switch Q2 and the other end of the sample hold capacitor C3 are grounded; The anode of the light-emitting diode of the photoelectric isolating switch Q2 is connected with the cathode of the diode D2, and the anode of the diode D2 is connected with the output end of the pulse generating circuit; The positive input end of the comparison chip IC8 is connected with the input end of the voltage dividing circuit I, and the output end of the comparison chip IC8 is used for being connected with a counter or an MCU chip.
6. The on-line capacitance detection circuit of an energy storage capacitor according to claim 1, wherein the voltage follower circuit comprises an operational amplifier chip IC1, the non-inverting input end of the operational amplifier chip IC1 is connected with the input end of the voltage follower circuit, and the output end of the operational amplifier chip IC1 is connected with the output end of the voltage follower circuit; The discharging circuit comprises a photoelectric isolating switch Q1, a resistor R2 and a resistor R3, wherein the resistor R2 and the resistor R3 are connected in series, the other end of the resistor R2 is connected with the first output end of the photoelectric isolating switch Q1, the second output end of the photoelectric isolating switch Q1 is connected with the input end of the discharging circuit, the cathode of a light emitting diode of the photoelectric isolating switch Q1 and the other end of the resistor R3 are grounded, the anode of the light emitting diode of the photoelectric isolating switch Q1 is connected with the first output end of the discharging circuit, and the connection point between the resistor R2 and the resistor R3 is connected with the second output end of the discharging circuit; the charging circuit comprises a voltage source DC1, an anti-reverse diode D1, a charging resistor R1 and an energy storage capacitor C1 which are connected in series, one end of the energy storage capacitor C1 is connected with the output end of the charging circuit, the other end of the voltage source DC1 and the other end of the energy storage capacitor C1 are grounded, and the junction between the anode of the anti-reverse diode D1 and the voltage source DC1 is connected with the input end of the charging circuit.
7. The on-line capacitance detection circuit of an energy storage capacitor according to claim 1, wherein the under-voltage detection circuit comprises a sampling resistor R4, a sampling resistor R5 and a comparison chip IC2, the sampling resistor R4 and the sampling resistor R5 are connected in series, a connection point between the sampling resistor R4 and the sampling resistor R5 is connected with a reverse input end of the comparison chip IC2, a forward input end of the comparison chip IC2 is connected with a reference voltage source vref, the other end of the sampling resistor R4 is connected with an input end of the under-voltage detection circuit, the other end of the sampling resistor R5 is grounded, and an output end of the comparison chip IC2 is connected with an output end of the under-voltage detection circuit; The pulse generation circuit comprises a resistor R6, a filter capacitor C2 and an exclusive-OR gate chip IC3, wherein the resistor R6 and the filter capacitor C2 are connected in series, the other end of the resistor R6 is connected with the input end of the pulse generation circuit, the other end of the resistor R6 is also connected with the first input end of the exclusive-OR gate chip IC3, the connection point of the resistor R6 and the filter capacitor C2 is connected with the second input end of the exclusive-OR gate chip IC3, the filter capacitor C2 is grounded, and the output end of the exclusive-OR gate chip IC3 is connected with the output end of the pulse generation circuit.
8. An online capacitance detection method of an energy storage capacitor for implementing a circuit according to any one of claims 1 to 7, wherein the energy storage capacitor C1 is a detection object, and the voltage source DC1 participates in online capacitance detection of the energy storage capacitor C1, and is used as a start input signal of a detection circuit, and specifically includes: detecting an undervoltage state of the voltage source DC1 through an undervoltage detection circuit; When an under-voltage state is detected, the discharging circuit is controlled to discharge the energy storage capacitor C1; outputting a voltage signal of the energy storage capacitor C1 through a voltage follower circuit; the voltage proportional value of the energy storage capacitor C1 is respectively output through the first voltage dividing circuit and the first voltage dividing circuit; Under the control of the narrow pulse output by the pulse generating circuit, the sampling and holding circuit stores the output voltage proportion value of the storage chip IC 1; The sampling hold circuit compares the output voltage of the operational amplifier chip IC1 with the voltage of the sampling hold capacitor C3 and outputs a square wave signal, and the square wave signal period reflects the capacitance value of the energy storage capacitor C1; and the cyclic detection of the capacitance value of the energy storage capacitor C1 is realized through a pulse output circuit.
9. The method for detecting the online capacitance of the storage capacitor according to claim 8, wherein the undervoltage state of the voltage source DC1 is detected by the undervoltage detection circuit, and the comparison chip IC2 outputs a high level when the divided voltage values of the sampling resistor R4 and the sampling resistor R5 are lower than the reference voltage source Vref.
10. The method for detecting the online capacitance of the energy storage capacitor according to claim 8, wherein the pulse generating circuit outputs a narrow pulse through the filter resistor R6, the filter capacitor C2 and the exclusive or gate chip IC3, and the photo-isolation switch Q2 is turned on when short, so that the sample-hold capacitor C3 stores the output voltage ratio value of the operational amplifier chip IC1 at the moment.

Description

Online capacitance detection circuit and method for energy storage capacitor Technical Field The invention relates to the technical field of electronics, in particular to an on-line capacitance detection circuit and method for an energy storage capacitor. Background Storage capacitors play an extremely important role in modern power electronics. The primary function of the storage capacitor is to store electrical energy and release it quickly when needed to meet the instantaneous power demands of the device. For example, in a bypass trigger plate, an energy storage capacitor is used to provide enough energy for triggering the thyristor, ensuring that the bypass switch can be closed quickly and reliably. Although the storage capacitor has a key role in the power electronics system, its lifetime is generally shorter than that of other semiconductor devices such as thyristors and freewheeling diodes. The capacity of the energy storage capacitor gradually decreases with the increase of the service time, which affects the energy storage capacity and the energy release efficiency. When the capacitance of the energy storage capacitor is reduced to a certain degree, the bypass switch can not be normally closed, and then the normal operation of the whole power system is affected. Therefore, monitoring the capacitance of the storage capacitor is needed. However, during normal operation of the bypass trigger plate, the voltage of the storage capacitor is in a stable state, and capacitance detection is difficult. The existing detection mode generally needs to finish the capacity value detection in the power failure process of the bypass trigger plate when the power module is powered down for maintenance, and report the detection result to the controller. The detection method is time-consuming and labor-consuming, the health state of the capacitor cannot be monitored in real time, and high requirements of a modern power electronic system on reliability and efficiency are difficult to meet. Disclosure of Invention The invention aims to provide an on-line capacitance detection circuit and method for an energy storage capacitor, wherein the detection circuit for the capacitance of the energy storage capacitor C1 is adopted, so that the width of a signal output by the detection circuit is in direct proportion to the capacitance of the energy storage capacitor C1, the detection of the capacitance of the energy storage capacitor C1 can be realized, and the problems that the traditional capacitance detection method cannot be on-line, depends on software and the like are solved. In order to achieve the above purpose, the present invention is realized by the following technical scheme: The on-line capacitance detection circuit comprises a charging circuit, a discharging circuit, a voltage follower circuit, an undervoltage detection circuit, a pulse generation circuit, a two-pole equal-proportion voltage dividing circuit, a sampling and holding circuit and a pulse output circuit, wherein the input end of the undervoltage detection circuit is connected with the input end of the charging circuit, the output end of the charging circuit is connected with the input end of the discharging circuit, the output end of the discharging circuit is connected with the input end of the voltage follower circuit, the output end of the voltage follower circuit is respectively connected with the input end I of the two-pole equal-proportion voltage dividing circuit and the input end I of the pulse output circuit, the output end of the pulse output circuit is connected with a sampling protection circuit, and the input end II of the pulse output circuit is connected with the output end II of the two-pole equal-proportion voltage dividing circuit; The input end I of the two-pole equal-proportion voltage dividing circuit and the input end II of the two-pole equal-proportion voltage dividing circuit are connected with the sampling protection circuit, and the output end I of the two-pole equal-proportion voltage dividing circuit is connected with the sampling protection circuit; the output end of the undervoltage detection circuit is respectively connected with the output end I of the discharge circuit and the input end of the pulse generation circuit, and the output end of the pulse generation circuit is connected with the sample hold circuit. The two-pole equal-proportion voltage dividing circuit comprises a first voltage dividing circuit and a second voltage dividing circuit, wherein the input end of the first voltage dividing circuit is connected with the output end of the voltage follower circuit, the input end of the first pulse output circuit and the sampling protection circuit respectively, the output end of the first voltage dividing circuit is connected with the sampling protection circuit, the input end of the second voltage dividing circuit is connected with the sampling protection circuit, and the output end of the second voltage dividing cir