CN212111618U - Capacitance polarity reverse connection detection device and system - Google Patents
Capacitance polarity reverse connection detection device and system Download PDFInfo
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- CN212111618U CN212111618U CN201922488890.6U CN201922488890U CN212111618U CN 212111618 U CN212111618 U CN 212111618U CN 201922488890 U CN201922488890 U CN 201922488890U CN 212111618 U CN212111618 U CN 212111618U
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Abstract
The utility model provides an electric capacity polarity reversal detection device and system, this electric capacity polarity reversal detection device includes: the voltage detection module is used for respectively detecting the branch voltage at two ends of each series branch in the frequency converter; the current detection module is used for detecting the loop current output by the test power supply; the voltage comparison module is used for sending a first detection result signal for indicating that electrolytic capacitors with reversed polarities exist in each series branch when the branch voltage of at least one series branch exceeds a voltage threshold value according to the branch voltage detected by the voltage detection module; and the current comparison module is used for sending out a second detection result signal for indicating that the electrolytic capacitors with reversed polarities exist in each series branch when the branch voltage of any series branch does not exceed the voltage threshold and the loop current is greater than the current threshold. The scheme can accurately detect the electrolytic capacitor with reversed polarity.
Description
Technical Field
The utility model relates to an electrical engineering technical field especially relates to electric capacity polarity reversal detection device and system.
Background
An inverter is widely used in the field of motor control, and an electrolytic capacitor is provided on the dc bus side of the inverter in order to enable the inverter to output a stable dc power. The connection relation between the electrolytic capacitor and the direct current bus of the frequency converter is as follows: the plurality of electrolytic capacitors are connected in parallel to form a series branch, and the plurality of series branches are connected in series to form a loop and connected with a direct current bus of the frequency converter.
In order to ensure that the frequency converter after leaving the factory can be normally used, various functions and hardware structures of the frequency converter need to be detected before leaving the factory, which includes detecting whether an electrolytic capacitor with reversed polarity exists on the direct current bus side of the frequency converter, because the electricity storage capacity of the electrolytic capacitor is related to the direction of current passing through the electrolytic capacitor, if the polarity of the electrolytic capacitor is reversed, the voltage balance of each series branch circuit can be influenced, and the electrolytic capacitor can be damaged in serious cases.
At present, when detecting whether the polarity of an electrolytic capacitor on the direct current bus side of a frequency converter is reversely connected, the voltage of each series branch is detected respectively, and when the voltage of one series branch exceeds a set voltage threshold, it is determined that the electrolytic capacitor with the reverse polarity exists in the series branch.
Aiming at the existing method for detecting the polarity reversal of the capacitor, when the electrolytic capacitors with the polarity reversal do not exist in each series branch mutually connected in series at the direct current bus side of the frequency converter, each series branch has similar voltage division capability, each series branch equally divides the input voltage applied on the direct current bus, and when the electrolytic capacitors with the polarity reversal exist in each series branch, each series branch still has similar voltage division capability, each series branch still equally divides the input voltage applied on the direct current bus, namely when the electrolytic capacitors with the polarity reversal exist in each series branch and when the electrolytic capacitors with the polarity reversal do not exist in each series branch, the voltages of each series branch are the same, so that the condition of leakage connection can occur, and the electrolytic capacitors with the polarity reversal cannot be accurately detected.
SUMMERY OF THE UTILITY MODEL
In view of this, the utility model provides a reverse detection device of electric capacity polarity and system can accurately detect out the electrolytic capacitor that polarity reversed.
In a first aspect, an embodiment of the present invention provides an electric capacity polarity reversal detection device, include:
the voltage detection module is used for respectively detecting branch circuit voltages at two ends of each series branch circuit in the frequency converter, wherein each series branch circuit comprises at least two electrolytic capacitors which are connected in parallel, and at least two series branch circuits are sequentially connected in series and then are connected with two poles of the test power supply;
a current detection module for detecting the loop current output by the test power supply;
a voltage comparison module, configured to send a first detection result signal indicating that an electrolytic capacitor with a reversed polarity exists in each of the series branches when the branch voltage of at least one of the series branches exceeds a voltage threshold according to the branch voltage detected by the voltage detection module;
and the current comparison module is used for sending a second detection result signal for indicating that electrolytic capacitors with reversed polarities exist in each series branch when the branch voltage of any series branch does not exceed the voltage threshold and the loop current is greater than the current threshold according to the branch voltage detected by the voltage detection module and the loop current detected by the current detection module.
Alternatively,
the voltage detection module comprises at least two voltage detectors, each voltage detector is connected with one series branch, and different voltage detectors are connected with different series branches;
for each series branch, one voltage detector connected with the series branch is mutually connected in parallel with each electrolytic capacitor in the series branch;
and the voltage detector is used for transmitting the detected branch voltage to the voltage comparison module.
Alternatively,
the voltage comparison module comprises: the voltage detection circuit comprises a voltage lower threshold output power supply, a voltage upper threshold output power supply and at least two voltage comparators;
each voltage comparator is connected with one voltage detector, and different voltage comparators are connected with different voltage detectors;
the voltage lower threshold output power supply is used for respectively transmitting the lower limit voltage of the voltage threshold to each voltage comparator;
the voltage upper threshold output power supply is used for respectively transmitting the upper limit voltage of the voltage threshold to each voltage comparator;
the voltage comparator is configured to obtain the branch voltage from the connected voltage detector, and send the first detection result signal when whether the obtained branch voltage is less than the lower limit voltage or greater than the upper limit voltage.
Alternatively,
the voltage comparator is further configured to send a first reverse connection positioning signal after it is determined that the acquired branch voltage is greater than the lower limit voltage and less than the upper limit voltage, where the first reverse connection positioning signal is used to indicate that the electrolytic capacitor with a reverse polarity exists in the series branch connected to the same voltage detector as the voltage comparator.
Alternatively,
the current detection module comprises a current detector;
the current detector is connected to a main loop between the test power supply and each series branch;
the current detector is used for detecting the loop current output by the test power supply to each series branch on the main loop and transmitting the loop current to the current comparison module.
Alternatively,
the current comparison module comprises: a current threshold output power supply and a current comparator;
the current threshold output power supply is used for supplying the threshold current to the current comparator;
the current comparator is configured to obtain the loop current from the current detector, and send the second detection result signal when the loop current is greater than the threshold current.
Alternatively,
the current comparator is further configured to send out a second reverse connection positioning signal when it is determined that the loop current is greater than the threshold current, where the second reverse connection positioning signal is used to indicate that the electrolytic capacitors with reversed polarities exist in each of the series branches.
Alternatively,
each series branch comprises at least one balance resistor connected with each electrolytic capacitor in parallel, so that each series branch has the same equivalent resistance.
In a second aspect, the embodiment of the present invention further provides a reverse connection detection system for capacitance polarity, including: a frequency converter to be subjected to capacitance polarity reversal detection, a test power supply and a capacitance polarity reversal detection device provided in the first aspect or any possible implementation manner of the first aspect;
at least two series branches are connected in series on the direct current bus side of the frequency converter, and each series branch comprises at least two electrolytic capacitors which are connected in parallel;
and two poles of the test power supply are connected with two ends of each series branch after being connected in series.
Alternatively,
the output voltage of the test power supply is 200V.
According to the technical scheme, the voltage threshold and the current threshold are set according to the output voltage of the test power supply and the balance current of each series branch in advance, when the electrolytic capacitors with reversed polarities do not exist in each series branch, the branch voltage of each series branch does not exceed the set voltage threshold, and the loop current flowing through each series branch does not exceed the current threshold. When detecting whether electrolytic capacitors with reversed polarities exist, the voltage detection module respectively detects branch voltage of each series branch, the current detection module detects loop current output by the test power supply, when the branch voltage of at least one series branch exceeds a voltage threshold, the voltage comparison module can determine that the electrolytic capacitors with reversed polarities exist in at least one series branch and send out a first detection result signal for indicating that the electrolytic capacitors with reversed polarities exist, when the branch voltage of all the series branches does not exceed the voltage threshold, the voltage comparison module can not determine whether the electrolytic capacitors with reversed polarities exist according to the branch voltage, the current comparison module further judges whether the loop current exceeds a current threshold, if the loop current exceeds the current threshold, the electrolytic capacitors with reversed polarities exist in each series branch can be determined, and a second detection result signal for indicating that the electrolytic capacitors with reversed polarities exist is correspondingly sent out, if the loop current does not exceed the current threshold, it can be determined that there is no electrolytic capacitor in each series branch with a reverse polarity. Therefore, the voltage comparison module and the current comparison module can detect the electrolytic capacitors with reversed polarities according to the branch currents of the series branches and the loop current of the loop formed by the series branches, and whether the electrolytic capacitors with reversed polarities exist in part of the series branches or all the series branches can be accurately detected, so that the accuracy of detecting the electrolytic capacitors with reversed polarities can be improved.
Drawings
Fig. 1 is a schematic diagram of a device for detecting reverse connection of capacitance polarity according to an embodiment of the present invention;
fig. 2 is a schematic diagram of another device for detecting reverse polarity of capacitance according to an embodiment of the present invention;
fig. 3 is a schematic diagram of a system for detecting reverse polarity connection of capacitors according to an embodiment of the present invention;
fig. 4 is a schematic diagram of another system for detecting reverse polarity of capacitance according to an embodiment of the present invention;
fig. 5 is a schematic diagram of another device for detecting reverse polarity of a capacitor according to an embodiment of the present invention;
fig. 6 is a schematic diagram of another capacitor polarity reversal detection apparatus according to an embodiment of the present invention;
fig. 7 is a schematic diagram of another capacitance polarity reversal detection system according to an embodiment of the present invention.
List of reference numerals:
10: the voltage detection module 20: the current detection module 30: voltage comparison module
40: the current comparison module 50: the frequency converter 60: test power supply
100: capacitance polarity reversal detection device 101: the voltage detector 301: output power supply with lower voltage threshold
302: upper voltage threshold output power supply 303: voltage comparator E1: test power supply
K1: switch C11: electrolytic capacitor C1 n: electrolytic capacitor
C21: electrolytic capacitor C2 n: electrolytic capacitor C31: electrolytic capacitor
C3 n: electrolytic capacitor R1: balance resistance R2: balance resistance
R3: balance resistance VM 1: voltage detector VM 2: voltage detector
VM 3: voltage detector AM 1: the current detector 401: current threshold output power supply
402: current comparator 501: series branch
Detailed Description
As described above, the dc bus side of the frequency converter is provided with a plurality of series branches connected in series, each series branch includes a plurality of electrolytic capacitors connected in parallel, when it is determined whether there is an electrolytic capacitor with a reversed polarity in each series branch by detecting the branch voltage of each series branch, when there is an electrolytic capacitor with a reversed polarity in each series branch, the divided voltage of each series branch is the same as that of each series branch when there is no electrolytic capacitor with a reversed polarity, and therefore, a correct detection result cannot be obtained when there is an electrolytic capacitor with a reversed polarity in each series branch according to the branch voltage of each series branch, and thus, an electrolytic capacitor with a reversed polarity cannot be accurately detected.
In the embodiment of the utility model, when detecting whether the electrolytic capacitor with reversed polarity exists at the direct current bus side of the frequency converter, the voltage detection module detects the branch voltage of each series branch respectively, the current detection module detects the loop current of each series branch, the voltage comparison module can determine the condition that the polarity of the electrolytic capacitor with reversed polarity exists in part of the series branches according to the branch voltage of each series branch, the current comparison module can determine the condition that all the series branches have electrolytic capacitors with reversed polarities according to the branch voltage and the loop current of each series branch, therefore, whether the electrolytic capacitors with the reversed polarities exist in part of the series branches or all the series branches can be accurately determined, and the accuracy of detecting whether the electrolytic capacitors with the reversed polarities exist can be improved.
The following describes in detail a capacitance polarity reversal detection device and system provided by embodiments of the present invention with reference to the accompanying drawings.
As shown in fig. 1, an embodiment of the present invention provides a device 100 for detecting reverse connection of capacitance polarity, which may include:
a voltage detection module 10, configured to detect a branch voltage at two ends of each series branch 501 in the frequency converter 50, respectively, where each series branch 501 includes at least two electrolytic capacitors connected in parallel, and at least two series branches 501 are connected in series in sequence and then connected to two poles of the test power supply 60;
a current detection module 20 for detecting the loop current output by the test power supply 60;
a voltage comparison module 30, configured to send a first detection result signal indicating that there is an electrolytic capacitor with reversed polarity in each series branch 501 when the branch voltage of at least one series branch 501 exceeds a voltage threshold according to the branch voltage detected by the voltage detection module 10;
and a current comparison module 40, configured to send a second detection result signal indicating that an electrolytic capacitor with a reversed polarity exists in each series branch 501 according to the branch voltage detected by the voltage detection module 10 and the loop current detected by the current detection module 20, when the branch voltage of any series branch 501 does not exceed the voltage threshold and the loop current is greater than the current threshold.
In the embodiment of the present invention, a voltage threshold and a current threshold are provided in advance according to the output voltage of the test power supply 60 and the balance current of each series branch 501, and when there is no electrolytic capacitor with reversed polarity in each series branch 501, the branch voltage of each series branch 501 does not exceed the set voltage threshold, and the loop current flowing through each series branch 501 does not exceed the current threshold. When detecting whether electrolytic capacitors with reversed polarities exist, the voltage detection module 10 detects branch voltages of each series branch 501 respectively, the current detection module 20 detects loop currents output by the test power supply 60, when the branch voltage of at least one series branch 501 exceeds a voltage threshold, the voltage comparison module 30 can determine that an electrolytic capacitor with reversed polarities exists in at least one series branch 501, sends a first detection result signal for indicating that an electrolytic capacitor with reversed polarities exists, when the branch voltages of all series branches 501 do not exceed the voltage threshold, the voltage comparison module 30 cannot determine whether an electrolytic capacitor with reversed polarities exists according to the branch voltages, the current comparison module 40 further determines whether the loop currents exceed a current threshold, and if the loop currents exceed the current threshold, it can determine that an electrolytic capacitor with reversed polarities exists in each series branch 501, a second detection result signal is correspondingly emitted for indicating the presence of a polarity-reversed electrolytic capacitor, and if the loop current does not exceed the current threshold, it can be determined that no polarity-reversed electrolytic capacitor is present in each series branch 501. Therefore, the voltage comparison module and the current comparison module can detect the electrolytic capacitors with reversed polarities according to the branch currents of the serial branches 501 and the loop current of the loop formed by the serial branches 501, and can accurately detect whether the electrolytic capacitors with reversed polarities exist in part of the serial branches 501 or all the serial branches 501, so that the accuracy of detecting the electrolytic capacitors with reversed polarities can be improved.
The embodiment of the present invention provides an embodiment, aiming at any one series branch 501, since the reverse leakage current of the electrolytic capacitor is significantly greater than the normal leakage current, when there is one or more polarity reversal electrolytic capacitors in this series branch 501, the partial pressure of this series branch 501 can be reduced, and the partial pressure is the branch voltage of this series branch 501, and then can determine whether there is polarity reversal electrolytic capacitor in this series branch 501 according to whether the branch voltage of this series branch 501 is less than the voltage threshold.
In the embodiment of the present invention, when there is no electrolytic capacitor with reversed polarity in each series branch 501, each series branch 501 has equivalent resistance approximately equal to each other, and each series branch 501 has branch voltage approximately equal to each other. Since the reverse leakage current of the electrolytic capacitor is significantly greater than the normal leakage current, when an electrolytic capacitor with reversed polarity exists in one of the series branches 501, the equivalent resistance of the series branch 501 may decrease to a lower level, and the influence of the number of electrolytic capacitors with reversed polarity in the same series branch 501 on the equivalent resistance of the series branch 501 is smaller, so that when an electrolytic capacitor with reversed polarity exists in each series branch 501, the equivalent resistance of each series branch 501 is still substantially equal, and each series branch 501 still has an approximate branch voltage. In summary, when the electrolytic capacitors with reversed polarities exist in all the serial branches 501, it is impossible to detect whether the electrolytic capacitors with reversed polarities exist in each serial branch 501 according to the branch voltage of each serial branch 501.
In the embodiment of the present invention, since the reverse leakage current of the electrolytic capacitor is significantly greater than the normal leakage current, when there is an electrolytic capacitor with reversed polarity in one series branch 501, the equivalent resistance of the series branch 501 will decrease to a lower level. If electrolytic capacitors with reversed polarities exist in all the series branches 501, the equivalent resistance of each series branch 501 is decreased, and on the premise that the test power supply 60 outputs a constant voltage, the loop current of a loop formed by the test power supply 60 and each series branch 501 is increased, so that when the branch voltage of each series branch 501 does not exceed the voltage threshold and the loop current exceeds the current threshold, the current comparison module 40 can determine that each series branch 501 includes an electrolytic capacitor with a reversed polarity according to the loop current detected by the current detection module 20, that is, can determine that an electrolytic capacitor with a reversed polarity exists in each series branch 501.
Alternatively, on the basis of the apparatus 100 for detecting reverse polarity connection of capacitors shown in fig. 1, as shown in fig. 2, the voltage detection module 10 may include a plurality of voltage detectors 101, each voltage detector 101 is connected to one serial branch 501, and different voltage detectors 101 are connected to different serial branches 501. Specifically, for each series branch 501, the voltage detector 101 connected to the series branch 501 is connected in parallel with each electrolytic capacitor in the series branch 501, and the voltage detector 101 connected to the series branch 501 is configured to detect a branch voltage at two ends of the series branch 501 and send the detected branch voltage to the voltage comparison module 30.
The embodiment of the utility model provides an in, because voltage detection module 10 is used for detecting the branch voltage of each series branch 501, and each series branch 501 is relatively independent, voltage detection module 10 is including a plurality of voltage detection ware 101 for this reason, different series branch 501 is connected to different voltage detection ware 101, and then different voltage detection ware 101 are used for detecting the branch voltage of different series branch 501, thereby can accurately detect out the branch voltage of each series branch 501, and then guarantee according to the accuracy of branch voltage detection polarity reversal's electrolytic capacitor.
In the embodiment of the present invention, according to the difference of the number of the serial branches 501 included in the frequency converter, the voltage detecting module 10 includes the voltage detectors 101 with different numbers. The following description is made separately for a frequency converter comprising two series branches 501 and for a frequency converter comprising three series branches 501.
As shown in fig. 3, in the 400V system, a first series branch and a second series branch are connected to a dc bus side of the frequency converter, the first series branch includes electrolytic capacitors C11 to C1n and a balancing resistor R1 connected in parallel, the second series branch includes electrolytic capacitors C21 to C2n and a balancing resistor R2 connected in parallel, and the first series branch and the second series branch are connected in series and then connected to two poles of a test power supply 60E 1. The voltage detection module 10 includes a voltage detector VM1 and a voltage detector VM2, the voltage detector VM1 is connected in parallel with each electrolytic capacitor in the first series branch, the voltage detector VM2 is connected in parallel with each electrolytic capacitor in the second series branch, the voltage detector VM1 is used for detecting the branch voltage of the first series branch, and the voltage detector VM2 is used for detecting the branch voltage of the second series branch.
As shown in fig. 4, in the 690V system, a second series branch and a third series branch are connected to a dc bus side of the frequency converter, the first series branch includes electrolytic capacitors C11 to C1n and a balance resistor R1 which are connected in parallel, the second series branch includes electrolytic capacitors C21 to C2n and a balance resistor R2 which are connected in parallel, the third series branch includes electrolytic capacitors C31 to C3n and a balance resistor R3 which are connected in parallel, and the first series branch, the second series branch and the third series branch are connected in series and then connected to two poles of a test power supply 60E 1. The voltage detection module 10 includes a voltage detector VM1, a voltage detector VM2, and a voltage detector VM3, the voltage detector VM1 is connected in parallel with each electrolytic capacitor in the first series branch, the voltage detector VM2 is connected in parallel with each electrolytic capacitor in the second series branch, the voltage detector VM3 is connected in parallel with each electrolytic capacitor in the third series branch, the voltage detector VM1 is configured to detect a branch voltage of the first series branch, the voltage detector VM2 is configured to detect a branch voltage of the second series branch, and the voltage detector VM3 is configured to detect a branch voltage of the third series branch.
In fig. 3 and 4, the power supply E1 is the test power supply 60, and when the test of the presence of the electrolytic capacitor with reversed polarity in the frequency converter 50 is started, the switch K1 is closed, the voltage detectors start to detect the branch voltage of the corresponding series branch 501, and the current detectors start to detect the loop current.
In the embodiment of the present invention, the voltage detector may be various voltmeters, multimeters, etc. having a voltage value output function.
Optionally, on the basis of the detection apparatus 100 with reversed polarity of the capacitor shown in fig. 2, as shown in fig. 5, the voltage comparison module 30 includes: a lower voltage threshold output power supply 301, an upper voltage threshold output power supply 302 and at least two voltage comparators 303;
each voltage comparator 303 is connected to one voltage detector 101, and different voltage comparators 303 are connected to different voltage detectors 101;
a lower-limit voltage threshold output power supply 301 for supplying a lower-limit voltage of a voltage threshold to each of the voltage comparators 303, respectively;
an upper voltage threshold output power supply 302 for supplying an upper voltage of a voltage threshold to each of the voltage comparators 303, respectively;
the voltage comparator 303 is configured to obtain a branch voltage from the connected voltage detector 101, and send a first detection result signal when the obtained branch voltage is smaller than a lower limit voltage or larger than an upper limit voltage.
In the embodiment of the present invention, because the output voltage of the test power supply 60 remains unchanged, when the branch voltage of the partial series branch 101 is reduced, the branch voltage of the other partial series branch 101 is increased, the normal fluctuation and the voltage detection error of the voltage are considered, it can be determined that a voltage interval range is used as the voltage threshold, the lower limit of the voltage threshold is provided to the voltage comparator 303 by the voltage lower limit threshold output power 301, the upper limit of the voltage threshold is provided to the voltage comparator 303 by the voltage upper limit threshold output power 302, and then the voltage comparator 303 can determine whether the received branch voltage is located the voltage threshold range, and then determine whether there is the electrolytic capacitor with reversed polarity in the corresponding series branch 101, and send out the first detection result signal after determining the electrolytic capacitor with reversed polarity.
In the embodiment of the present invention, the voltage threshold can be specifically determined according to the output voltage of the test power supply 60 and the equivalent resistance of each series branch. For example, the voltage threshold may be determined to be (-3% V, 3% V), where V is used to characterize the output voltage of the test power supply 60.
Alternatively, on the basis of the apparatus 100 for detecting polarity reversal of capacitance shown in fig. 5, when one voltage comparator 303 determines that the acquired branch voltage is smaller than the lower limit voltage or larger than the upper limit voltage, the voltage comparator 303 may further send out a first reversal positioning signal, where the first reversal positioning signal is used to indicate that there is an electrolytic capacitor with polarity reversal in the series branch 501 connected to the same voltage detector 101 as the voltage comparator 303.
The embodiment of the utility model provides an in, when voltage comparator 303 confirms that the branch circuit voltage that detects rather than the voltage detector 101 that is connected is less than lower limit voltage or is greater than upper limit voltage, this voltage comparator 303 can send first transposition locating signal, and then the user can confirm to have the electrolytic capacitor that polarity joins conversely in the series branch 501 corresponding with this voltage comparator 303 according to first transposition locating signal, thereby realize the location of the electrolytic capacitor that polarity joins conversely, make the user can more conveniently seek the electrolytic capacitor that polarity joins conversely, and then handle the electrolytic capacitor that polarity joins conversely.
It should be noted that the voltage comparator 303 may be implemented by a voltage comparison logic circuit, for example, the branch voltage may be compared with the upper limit voltage and the lower limit voltage by a logic device such as a MOS transistor or a triode, and then the first detection result signal and the first reverse connection positioning signal are sent by turning on or off the corresponding pin.
Alternatively, on the basis of the apparatus 100 for detecting reverse polarity connection of capacitors shown in fig. 1, the current detecting module 20 may include a current detector connected to the main circuit between the test power supply 60 and each series branch 501, and the current detector is configured to detect a loop current output by the test power supply 60 to each series branch 501 on the main circuit, and transmit the detected loop current to the current comparing module 40.
In the embodiment of the present invention, because electrolytic capacitor's reverse leakage current is obviously greater than normal leakage current, when there is the electrolytic capacitor that polarity joins conversely in each series branch 501, each series branch 501's equivalent resistance sum reduces, the loop current increase of closed circuit that constitutes after each series branch 501 is connected with test power supply 60, consequently, can calculate the current threshold according to test power supply 60's output voltage and each series branch 501's equivalent resistance, and utilize the current detector who sets up between test power supply 60 and series branch 501 to detect the loop current, and then current ratio module 40 can confirm whether there is the electrolytic capacitor that polarity joins conversely in each series branch according to loop current and current threshold.
In the embodiment of the present invention, the current threshold may be determined in advance according to the output voltage of the test power supply 60 and the equivalent resistance of each series branch 501, for example, the current threshold may be set
Where V is used to characterize the output voltage of the test power supply 60 and R is used to characterize the equivalent resistance of each series branch.
In the embodiment of the present invention, the current detector may be various ammeters, multimeters, or the like having a current value output function.
Alternatively, on the basis that the current detection module 20 includes a current detector, as shown in fig. 6, the current comparison module 40 includes: a current threshold output power source 401 and a current comparator 402;
a current threshold output power supply 401 for supplying a threshold current to the current comparator 402;
and a current comparator 402 for obtaining the loop current from the current detector and generating a second detection result signal when the loop current is greater than the threshold current.
In the embodiment of the present invention, because the reverse leakage current of the electrolytic capacitor is obviously greater than the normal leakage current, when the electrolytic capacitor with reversed polarity exists in each series branch 501, the sum of the equivalent resistance of each series branch 501 is reduced, the loop current of the closed loop formed after each series branch 501 is connected to the test power supply 60 is increased, therefore, after the current comparator 402 determines that the loop current detected by the current detector is greater than the current threshold, the electrolytic capacitor with reversed polarity exists in at least one series branch 501 can be determined in each series branch 501, and the second detection result signal is correspondingly sent.
In the embodiment of the present invention, the current threshold output power source 401 may be configured by a power source, a power source set or a circuit of the function output stabilization current.
Alternatively, on the basis of the apparatus 100 for detecting polarity reversal of capacitance shown in fig. 6, after the current comparator 402 determines that the loop current is greater than the threshold current, the current comparator 402 may further output a second reversal locating signal, where the second reversal locating signal is used to indicate that there is an electrolytic capacitance with polarity reversal in each series branch 501.
The embodiment of the utility model provides an in, after the branch road voltage that module 30 confirms not to have series branch road 501 exceeds the voltage threshold value at voltage ratio, if the current comparator 402 among the module 40 of current ratio confirms that loop current is greater than the current threshold value, then explain the obvious decline that each series branch road 501's equivalent resistance produced, and then current comparator 402 can confirm that all there is the electrolytic capacitor that polarity joins conversely in each series branch road 501, realize the electrolytic capacitor polarity location to polarity joins conversely in the converter, and then the user can more conveniently seek the electrolytic capacitor that polarity joins conversely, and carry out repairing process to the electrolytic capacitor that polarity joins conversely.
Optionally, as shown in fig. 3 and 4, each series branch 501 includes at least one balancing resistor connected in parallel with each electrolytic capacitor, so that each series branch has the same equivalent resistance.
The embodiment of the utility model provides an in, because there may be the performance difference between the different electrolytic capacitor, different electrolytic capacitor may have different equivalent resistance promptly, through parallelly connected balanced resistance in each series branch 501, can make different series branch 501 have the same equivalent resistance, and then balanced each partial pressure of establishing ties branch 501, avoid each series branch 501 because the partial pressure is unbalanced and lead to the condition emergence that electrolytic capacitor damaged, guaranteed the security of converter.
As shown in fig. 7, an embodiment of the present invention provides a capacitance electrode reverse connection detection system, including: a frequency converter 50 to be tested for capacitance polarity reversal, a test power supply 60 and a capacitance polarity reversal testing device 100 provided by any of the above embodiments;
at least two series branches 501 are connected in series on the direct current bus side of the frequency converter 50, and each series branch 501 comprises at least two electrolytic capacitors which are connected in parallel;
the two poles of the test power supply 60 are connected to the two ends of each series branch 501 after being connected in series.
Alternatively, the output voltage of the test power supply 60 may be 200V based on the capacitive electrode reversal detection system shown in fig. 7.
When the output voltage of the test power supply 60 is small, the measurement resolution of the branch voltage and the loop current is low, and the branch voltage of each series branch 501 changes slowly, so that the condition of polarity reversal of the electrolytic capacitor cannot be detected, and when the output voltage of the test power supply 60 is large, the frequency converter 60 to be detected may be damaged due to failure, so that the test power supply 60 with the output voltage of 200V can be selected to perform polarity reversal detection of the capacitor, and the test accuracy and the test safety are guaranteed.
It should be noted that not all steps and modules in the above flows and system structure diagrams are necessary, and some steps or modules may be omitted according to actual needs. The execution order of the steps is not fixed and can be adjusted as required. The system structure described in the above embodiments may be a physical structure or a logical structure, that is, some modules may be implemented by the same physical entity, or some modules may be implemented by a plurality of physical entities, or some components in a plurality of independent devices may be implemented together.
In the above embodiments, the hardware unit may be implemented mechanically or electrically. For example, a hardware element may comprise permanently dedicated circuitry or logic (such as a dedicated processor, FPGA or ASIC) to perform the corresponding operations. The hardware elements may also comprise programmable logic or circuitry, such as a general purpose processor or other programmable processor, that may be temporarily configured by software to perform the corresponding operations. The specific implementation (mechanical, or dedicated permanent, or temporarily set) may be determined based on cost and time considerations.
The present invention has been shown and described in detail with reference to the drawings and the preferred embodiments, however, the present invention is not limited to the disclosed embodiments, and those skilled in the art can understand that the code auditing means in the above different embodiments can be combined to obtain more embodiments of the present invention, and these embodiments are also within the scope of the present invention.
Claims (10)
1. Capacitance polarity reversal detection device (100), characterized by, includes:
the voltage detection module (10) is used for respectively detecting branch circuit voltages at two ends of each series branch circuit (501) in the frequency converter (50), wherein each series branch circuit (501) comprises at least two electrolytic capacitors which are mutually connected in parallel, and at least two series branch circuits (501) are sequentially connected in series and then are connected with two poles of the test power supply (60);
a current sensing module (20) for sensing a loop current output by said test power supply (60);
a voltage comparison module (30) for sending a first detection result signal indicating that there is an electrolytic capacitor with reversed polarity in each of the series branches (501) when the branch voltage of at least one of the series branches (501) exceeds a voltage threshold according to the branch voltage detected by the voltage detection module (10);
and the current comparison module (40) is used for sending a second detection result signal for indicating that electrolytic capacitors with reversed polarities exist in each series branch (501) when the branch voltage of any series branch (501) does not exceed the voltage threshold and the loop current is greater than the current threshold according to the branch voltage detected by the voltage detection module (10) and the loop current detected by the current detection module (20).
2. The apparatus of claim 1,
the voltage detection module (10) comprises at least two voltage detectors (101), each voltage detector (101) is connected with one series branch (501), and different voltage detectors (101) are connected with different series branches (501);
for each series branch (501), one voltage detector (101) connected with the series branch (501) is connected with each electrolytic capacitor in the series branch (501) in parallel;
the voltage detector (101) is used for transmitting the detected branch voltage to a voltage comparison module (30).
3. The apparatus of claim 2, wherein the voltage comparison module (30) comprises: a lower voltage threshold output power supply (301), an upper voltage threshold output power supply (302) and at least two voltage comparators (303);
each of the voltage comparators (303) is connected to one of the voltage detectors (101), and different ones of the voltage comparators (303) are connected to different ones of the voltage detectors (101);
the voltage lower limit threshold output power supply (301) is used for respectively supplying the lower limit voltage of the voltage threshold to each voltage comparator (303);
the voltage upper threshold output power supply (302) is used for respectively supplying the upper limit voltage of the voltage threshold to each voltage comparator (303);
the voltage comparator (303) is configured to obtain the branch voltage from the connected voltage detector (101), and send the first detection result signal when whether the obtained branch voltage is smaller than the lower limit voltage or larger than the upper limit voltage.
4. The apparatus of claim 3,
the voltage comparator (303) is further configured to send out a first reverse connection positioning signal after determining that the acquired branch voltage is greater than the lower limit voltage and less than the upper limit voltage, where the first reverse connection positioning signal is used to indicate that the electrolytic capacitor with a reverse polarity exists in the series branch (501) connected to the same voltage detector (101) as the voltage comparator (303).
5. The apparatus of claim 1,
the current detection module (20) comprises a current detector;
the current detector is connected to a main loop between the test power supply (60) and each of the series branches (501);
the current detector is configured to detect the loop current output by the test power supply (60) to each of the series branches (501) on the main loop, and transmit the loop current to the current comparison module (40).
6. The apparatus of claim 5, wherein the current comparison module (40) comprises: a current threshold output power source (401) and a current comparator (402);
the current threshold output power supply (401) for delivering a threshold current to the current comparator (402);
the current comparator (402) is configured to obtain the loop current from the current detector, and to issue the second detection result signal when the loop current is greater than the threshold current.
7. The apparatus of claim 6,
the current comparator (402) is further configured to issue a second reverse connection positioning signal when it is determined that the loop current is greater than the threshold current, wherein the second reverse connection positioning signal is used to indicate that the electrolytic capacitors with reversed polarities exist in each of the series branches (501).
8. The device according to any one of claims 1 to 7,
each series branch (501) comprises at least one balance resistor connected with each electrolytic capacitor in parallel, so that each series branch (501) has the same equivalent resistance.
9. Capacitance polarity reversal detecting system, its characterized in that includes: a frequency converter (50) to be tested for reverse capacitive polarity, a test power supply (60) and a reverse capacitive polarity detection device (100) according to any one of claims 1 to 8;
at least two series branches (501) are connected in series on the direct current bus side of the frequency converter (50), and each series branch (501) comprises at least two electrolytic capacitors which are connected in parallel;
two poles of the test power supply (60) are connected with two ends of each series branch (501) after being connected in series.
10. The system of claim 9,
the output voltage of the test power supply (60) is 200V.
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| CN113933593A (en) * | 2021-10-27 | 2022-01-14 | 江苏上上电缆集团有限公司 | Large-section cable conductor alternating current equivalent resistance test system and method based on current comparator |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| CN113933593A (en) * | 2021-10-27 | 2022-01-14 | 江苏上上电缆集团有限公司 | Large-section cable conductor alternating current equivalent resistance test system and method based on current comparator |
| CN113933593B (en) * | 2021-10-27 | 2023-08-22 | 江苏上上电缆集团有限公司 | Current comparator-based large-section cable conductor alternating-current equivalent resistance test system and method |
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