CN111060812A - Detection circuit and detection method - Google Patents

Detection circuit and detection method Download PDF

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Publication number
CN111060812A
CN111060812A CN202010189391.1A CN202010189391A CN111060812A CN 111060812 A CN111060812 A CN 111060812A CN 202010189391 A CN202010189391 A CN 202010189391A CN 111060812 A CN111060812 A CN 111060812A
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voltage signal
resistance
resistor
switch module
detection value
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CN111060812B (en
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李盟
侯贻真
刘昌鑑
叶伏明
颜利丹
但志敏
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Jiangsu Contemporary Amperex Technology Ltd
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Jiangsu Contemporary Amperex Technology Ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/28—Testing of electronic circuits, e.g. by signal tracer
    • G01R31/282—Testing of electronic circuits specially adapted for particular applications not provided for elsewhere
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36—Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/389—Measuring internal impedance, internal conductance or related variables

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  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Testing Of Short-Circuits, Discontinuities, Leakage, Or Incorrect Line Connections (AREA)

Abstract

The embodiment of the invention relates to the technical field of circuits, and discloses a detection circuit and a detection method. A detection circuit, comprising: the device comprises a controller, a battery pack, a first switch module, a second switch module, a DCLink capacitor and a detection module; the controller controls the signal generator to output an alternating voltage signal and respectively collects a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor; the controller is further configured to obtain an outside resistance detection value according to at least the first voltage signal and the second voltage signal, where the outside resistance detection value is a parallel connection value of an outside insulation resistance of the second end of the first switch module and an outside insulation resistance of the second end of the second switch module. According to the invention, the outer side insulation performance of the first switch module and the second switch module can be estimated in advance before the first switch module and the second switch module are not closed, so that the first switch module and the second switch module are prevented from being closed when the outer side insulation performance fails.

Description

Detection circuit and detection method
Technical Field
The embodiment of the invention relates to the technical field of circuits, in particular to a detection circuit and a detection method.
Background
With the development of battery technology, the electric automobile replacing fuel automobile has become the development trend of automobile industry. The power battery pack is a key part of the electric automobile, two sides of a relay of the electric automobile are respectively grounded, and the insulating property of the electric automobile can be detected when the relay is closed, so that the safety of high voltage electricity is ensured.
The inventor finds that at least the following problems exist in the prior art: when the outside insulation resistance of the relay of the electric automobile is detected, all relays or unilateral relays need to be closed first, and the risk of electric shock of a human body exists.
Disclosure of Invention
The purpose of the embodiments of the present invention is to provide a detection circuit and a detection method, which can estimate the outside insulation performance of a first switch module and a second switch module in advance before the first switch module and the second switch module are not closed, so as to avoid closing the first switch module and the second switch module when the outside insulation performance fails, and reduce the risk of electric shock during high-voltage power-on as much as possible; meanwhile, the fault of the detection circuit can be conveniently found in time, and the short circuit of the battery pack is avoided.
To solve the above technical problem, an embodiment of the present invention provides a detection circuit, including: the device comprises a controller, a battery pack, a first switch module, a second switch module, a DCLink capacitor and a detection module; two ends of the battery pack are respectively connected to the first end of the first switch module and the first end of the second switch module, and the second end of the first switch module is connected to the second end of the second switch module through a DCLink capacitor; the first end of the detection module is connected to the reference potential end, and the second end of the detection module is connected to the second end of the second switch module; the detection module comprises a signal generator, a first resistor and a first capacitor, wherein the first end of the signal generator forms the first end of the detection module, the second end of the signal generator is connected to the first end of the first resistor, the second end of the first resistor is connected to the first end of the first capacitor, and the second end of the first capacitor forms the second end of the detection module; the controller is connected with the signal generator; the controller is used for controlling the signal generator to output an alternating voltage signal; the controller is used for respectively acquiring a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor; the controller is further configured to obtain an outside resistance detection value according to at least the first voltage signal and the second voltage signal, where the outside resistance detection value is a parallel connection value of an outside insulation resistance of the second end of the first switch module and an outside insulation resistance of the second end of the second switch module.
The embodiment of the invention also provides a detection method which is applied to a controller of a detection circuit, wherein the detection circuit further comprises a battery pack, a first switch module, a second switch module, a DCLink capacitor and a detection module, and the detection module comprises a signal generator, a first resistor and a first capacitor; the method comprises the following steps: the control signal generator outputs an alternating voltage signal; respectively collecting a first voltage signal of a first end of a first resistor and a second voltage signal of a second end of the first resistor; and obtaining an outer resistance detection value according to at least the first voltage signal and the second voltage signal, wherein the outer resistance detection value is a parallel connection value of an outer insulation resistance of the second end of the first switch module and an outer insulation resistance of the second end of the second switch module.
Compared with the prior art, the controller can control the signal generator to output an alternating voltage signal, collect a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor, obtain a parallel value of an outer insulation resistor of the second end of the first switch module and an outer insulation resistor of the second end of the second switch module according to the first voltage signal and the second voltage signal, record the parallel value as an outer resistor detection value and the outer resistor detection value, and can represent outer insulation performance of the first switch module and the second switch module; namely, before the first switch module and the second switch module are not closed, the outer side insulation performance of the first switch module and the second switch module can be estimated in advance, the first switch module and the second switch module are prevented from being closed when the outer side insulation performance fails, and the electric shock risk of high-voltage electrification is reduced as much as possible; meanwhile, the fault of the detection circuit can be conveniently found in time, and the short circuit of the battery pack is avoided.
In addition, the detection circuit also comprises a plurality of sampling branches, each sampling branch at least comprises a third switch module and a second resistor which are connected with each other, and the plurality of sampling branches comprise a first sampling branch and a second sampling branch; the second end of the detection module is connected to the second end of the second switch module through a first sampling branch, the first end of the first switch module is connected to the joint of the detection module and the first sampling branch, and the second end of the first switch module is also connected to the first end of the second switch module through a second sampling branch; the controller is specifically used for controlling the third switch modules in the sampling branches to be in a closed state and respectively collecting a first voltage signal and a second voltage signal; the controller is specifically used for obtaining an outer resistance detection value at least according to the first voltage signal, the second voltage signal and the resistance value of the second resistor; the controller is further used for controlling the third switch modules in the sampling branches to be in an off state, and respectively collecting a third voltage signal of the first end of the first resistor and a fourth voltage signal of the second end of the first resistor; the controller is further configured to obtain an inner-side resistance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side resistance detection value is a parallel connection value of an inner-side insulation resistance of the first end of the first switch module and an inner-side insulation resistance of the first end of the second switch module. In this embodiment, the inside resistance detection value and the outside resistance detection value of the first switch module and the second switch module can be detected simultaneously, so that the insulation performance of the first switch module and the second switch module can be judged more accurately.
In addition, the detection circuit further includes: a plurality of Y capacitors; the first end of the first switch module and the first end of the second switch module are respectively connected to a reference potential end through different Y capacitors; the controller is specifically configured to obtain an inner-side resistance detection value and an inner-side capacitance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side capacitance detection value is a parallel value of a Y capacitor connected to the first end of the first switch module and a Y capacitor connected to the first end of the second switch module; the controller is used for obtaining an outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor. In this embodiment, the detection circuit including the Y capacitor can simultaneously detect the inner resistance detection value and the outer resistance detection value of the first switch module and the second switch module.
In addition, the controller is specifically configured to obtain an outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal, and the resistance value of the second resistor. In this embodiment, a specific implementation manner of obtaining the detected value of the outer resistance according to at least the first voltage signal and the second voltage signal is provided.
In addition, the controller is used for calculating the outer resistance detection value according to the first voltage signal, the second voltage signal and the resistance value of the second resistor when the inner resistance detection value is judged to be matched with the preset resistance threshold value and the inner capacitance detection value is judged to be matched with the preset capacitance threshold value; the controller is used for calculating the outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal and the second voltage signal when the inner resistance detection value is judged not to be matched with the preset resistance threshold value and/or the inner capacitance detection value is judged not to be matched with the preset capacitance threshold value. The embodiment provides a specific implementation mode for obtaining the outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
In addition, the controller is used for calculating the outer resistance detection value according to the first voltage signal, the second voltage signal and the resistance value of the second resistor when the inner resistance detection value is judged to be matched with the preset resistance threshold value; the controller is used for calculating the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor when the inner resistance detection value is judged not to be matched with the preset resistance threshold value. The embodiment provides a specific implementation mode for obtaining the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
In addition, the detection circuit also comprises a plurality of sampling circuits connected with the controller, and the plurality of sampling circuits comprise a first sampling circuit and a second sampling circuit; the controller is specifically used for collecting a first voltage signal of a first end of the first resistor through the first sampling circuit and collecting a second voltage signal of a second end of the first resistor through the second sampling circuit. This embodiment provides a specific implementation of collecting a first voltage signal and a second voltage signal.
In addition, each sampling circuit comprises a third resistor, a second capacitor, a voltage follower and a sampling unit; the controller is connected with the sampling unit of the sampling circuit; the first end of the third resistor is the input end of the sampling circuit, and the second end of the third resistor is connected to the reference potential end through the second capacitor; the first input end of the voltage follower is connected to the junction of the third resistor and the second capacitor, the second input end of the voltage follower is connected to the output end of the voltage follower, the output end of the voltage follower is further connected to one end of the sampling unit, and the other end of the sampling unit is connected to the controller. This embodiment provides a specific structure of a sampling circuit.
In addition, the detection circuit also comprises a plurality of sampling branches, each sampling branch at least comprises a third switch module and a second resistor which are connected with each other, and the plurality of sampling branches comprise a first sampling branch and a second sampling branch; the method further comprises the following steps: controlling a third switch module in each sampling branch circuit to be in an off state, and respectively collecting a third voltage signal of the first end of the first resistor and a fourth voltage signal of the second end of the first resistor; obtaining an inner resistance detection value according to the third voltage signal and the fourth voltage signal, wherein the inner resistance detection value is a parallel connection value of an inner insulation resistance of the first end of the first switch module and an inner insulation resistance of the first end of the second switch module; gather the first voltage signal of the first end of first resistance and the second voltage signal of the second end of first resistance respectively, specifically be: controlling a third switch module in each sampling branch to be in a closed state, and respectively collecting a first voltage signal and a second voltage signal; obtaining an outside resistance detection value at least according to the first voltage signal and the second voltage signal, specifically: and obtaining an outer resistance detection value at least according to the first voltage signal, the second voltage signal and the resistance value of the second resistor.
In addition, the detection circuit further includes: a plurality of Y capacitors; according to the third voltage signal and the fourth voltage signal, an inner side resistance detection value is obtained, and the method specifically comprises the following steps: obtaining an inner resistance detection value and an inner capacitance detection value according to the third voltage signal and the fourth voltage signal, wherein the inner capacitance detection value is a parallel value of a Y capacitor connected to the first end of the first switch module and a Y capacitor connected to the first end of the second switch module; obtaining an outside resistance detection value at least according to the first voltage signal and the second voltage signal, specifically: and obtaining an outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
In addition, an outside resistance detection value is obtained at least according to the first voltage signal, the second voltage signal and the resistance value of the second resistor, and specifically: and obtaining an outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
In addition, according to inboard resistance detection value, inboard electric capacity detection value, first voltage signal, second voltage signal and the resistance of second resistance, obtain outside resistance detection value, include: when the inner resistance detection value is judged to be matched with the preset resistance threshold value and the inner capacitance detection value is judged to be matched with the preset capacitance threshold value, calculating the outer resistance detection value according to the first voltage signal, the second voltage signal and the resistance value of the second resistor; and when the inner resistance detection value is judged not to be matched with the preset resistance threshold value and/or the inner capacitance detection value is judged not to be matched with the preset capacitance threshold value, calculating the outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal and the second voltage signal.
In addition, obtaining the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal, and the resistance value of the second resistor includes: when the inner resistance detection value is judged to be matched with the preset resistance threshold value, calculating the outer resistance detection value according to the first voltage signal, the second voltage signal and the resistance value of the second resistor; and when the inner resistance detection value is judged not to be matched with the preset resistance threshold value, calculating the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
Drawings
One or more embodiments are illustrated by way of example in the accompanying drawings, which correspond to the figures in which like reference numerals refer to similar elements and which are not to scale unless otherwise specified.
FIG. 1 is a block schematic diagram of a detection circuit according to a first embodiment of the present invention;
FIG. 2 is a circuit diagram of a detection circuit according to a first embodiment of the present invention;
FIG. 3 is a circuit diagram of a sampling circuit in a detection circuit according to a first embodiment of the present invention;
fig. 4 is an equivalent circuit diagram of a detection circuit according to the first embodiment of the present invention;
FIG. 5 is a circuit diagram of a detection circuit according to a second embodiment of the present invention;
fig. 6 is an equivalent circuit diagram for detecting the detection value of the inner side resistance of the detection circuit according to the second embodiment of the present invention;
fig. 7 is an equivalent circuit diagram for detecting the detection value of the outer resistance of the detection circuit according to the second embodiment of the present invention;
fig. 8 is an equivalent circuit diagram of the circuit diagram shown in fig. 7 according to the second embodiment of the present invention;
FIG. 9 is a circuit diagram of a detection circuit according to a third embodiment of the present invention;
fig. 10 is an equivalent circuit diagram for detecting the detection value of the inner side resistance of the detection circuit according to the third embodiment of the present invention;
fig. 11 is an equivalent circuit diagram for detecting the detection value of the outer resistance of the detection circuit according to the third embodiment of the present invention;
fig. 12 is an equivalent circuit diagram of the circuit diagram shown in fig. 11 according to the third embodiment of the present invention;
FIG. 13 is a detailed flowchart of a detection method according to a fourth embodiment of the present invention;
fig. 14 is a detailed flowchart of a detection method according to a fifth embodiment of the present invention;
fig. 15 is a detailed flowchart of a detection method according to a sixth embodiment of the present invention.
Detailed Description
In order to make the objects, technical solutions and advantages of the embodiments of the present invention more apparent, embodiments of the present invention will be described in detail below with reference to the accompanying drawings. However, it will be appreciated by those of ordinary skill in the art that numerous technical details are set forth in order to provide a better understanding of the present application in various embodiments of the present invention. However, the technical solution claimed in the present application can be implemented without these technical details and various changes and modifications based on the following embodiments.
A first embodiment of the present invention relates to a detection circuit applied to an electric vehicle, the detection circuit including: referring to fig. 1 and fig. 2, a controller 1, a battery pack 2, a first switch module 3, a second switch module 4, a DC Link capacitor Cx, and a detection module 5; the controller 1 is connected to the detection module 5, and in addition, the controller 1 is generally connected to the first switch module 3 and the second switch module 4. In this embodiment and the following embodiments, the first switch module 3 is taken as the main positive relay S1, and the second switch module 4 is taken as the main negative relay S2 for illustration. The controller can be a battery management system of the electric automobile; in the figure, the main positive relay S1 and the main negative relay S2 are schematically represented by switch symbols.
Two ends of the battery pack 2 are respectively connected to a first end of the first switch module 3 and a first end of the second switch module 4, a second end of the first switch module 3 is connected to a second end of the second switch module 4 through a DCLink capacitor Cx, namely, a positive electrode of the battery pack 2 is connected to a first end of the main positive relay S1, a negative electrode of the battery pack 2 is connected to a first end of the main negative relay S2, and a second end of the main positive relay S1 is connected to a second end of the main negative relay S2 through the DCLink capacitor Cx; a first end of the detection module 5 is connected to the reference potential end G, and a second end of the detection module 5 is connected to a second end of the second switch module 4 (main negative relay S2); in addition, both ends of the main positive relay S1 and both ends of the main negative relay S2 are connected to a reference potential terminal G, which may be a ground terminal of the electric vehicle; the first end of the main positive relay S1 and the first end of the main negative relay S2 are inside the relays, and the second end of the main positive relay S1 and the second end of the main negative relay S2 are outside the relays.
The detection module 5 comprises a signal generator (Direct Digital Synthesis, DDS for short), a first resistor R1, and a first capacitor C1, wherein a first end of the signal generator DDS forms a first end of the detection module 5, a second end of the signal generator DDS is connected to a first end of the first resistor R1, a second end of the first resistor R1 is connected to a first end of the first capacitor C1, and a second end of the first capacitor C1 forms a second end of the detection module 5; the controller 1 is connected to a signal generator DDS.
When the electric automobile is electrified at low voltage, the controller 1 enters a working state, the control signal generator DDS outputs an alternating voltage signal, and a first voltage signal of a first end of the first resistor R1 and a second voltage signal of a second end of the first resistor R1 are respectively collected; specifically, after the signal generator DDS outputs the ac voltage signal, the controller 1 collects a first voltage signal of a first end (i.e., a point a in fig. 2) of the first resistor R1 with respect to a reference potential end G (i.e., the reference potential end G connected to the signal generator DDS in fig. 2), where the first voltage signal is the ac voltage signal, and collects a second voltage signal of a second end (i.e., a point B in fig. 2) of the first resistor R1 with respect to the reference potential end G (i.e., the reference potential end G connected to the signal generator DDS in fig. 2).
In one example, the detection circuit further includes a plurality of sampling circuits 6 connected to the controller 1, the plurality of sampling circuits 6 including a first sampling circuit 61, a second sampling circuit 62; the controller 1 may be configured to collect a first voltage signal at a first end of the first resistor R1 through the first sampling circuit 61, and collect a second voltage signal at a second end of the first resistor R1 through the second sampling circuit 62. Specifically, the input terminal of the first sampling circuit 61 is connected to the point B for collecting a first voltage signal of the first terminal of the first resistor R1 with respect to the reference potential terminal G, and the input terminal of the second sampling circuit 62 is connected to the point a for collecting a second voltage signal of the second terminal of the first resistor R1 with respect to the reference potential terminal G. In the present embodiment, referring to fig. 3, each sampling circuit includes an RC filter (not shown), a voltage follower 601, and a sampling unit 602; the RC filter comprises a third resistor R3 and a second capacitor C2, wherein a first end of the third resistor R3 is an input end of the sampling circuit 6, and a second end of the third resistor R3 is connected to a reference potential end G through the second capacitor C2; the first input end of the voltage follower 601 is connected to the connection point of the third resistor R3 and the second capacitor C2, the second input end of the voltage follower 601 is connected to the output end of the voltage follower 601, the output end of the voltage follower 601 is further connected to one end of the sampling unit 602, and the other end of the sampling unit 602 is connected to the controller 1. It should be noted that, in this embodiment, fig. 2 schematically illustrates the first sampling circuit 61 and the second sampling circuit 62, and the first sampling circuit 61 and the second sampling circuit 62 are not illustrated in the following drawings, but do not represent that the first sampling circuit 61 and the second sampling circuit 62 are not included in the detection circuit.
The controller 1 is further configured to obtain an outside resistance detection value based on at least the first voltage signal and the second voltage signal, where the outside resistance detection value is a parallel connection value of an outside insulation resistance of the second end of the main positive relay S1 and an outside insulation resistance of the second end of the main negative relay S2. In this embodiment and the following embodiments, the insulation resistances of the main positive relay S1 and the main negative relay S2 inside and outside, that is, the insulation resistances of the main positive relay S1 and the main negative relay S2 on the side close to the battery pack 2 and on the side close to the capacitor Cx are schematically drawn in the figures, and specifically include: insulation resistance R of the inner side of main positive relay S1 to reference potential terminal GP1With main negative relay S2Insulation resistance R of side-to-side reference potential terminal GN1Insulation resistance R of the outer side of the main positive relay S1 to the reference potential terminal GP2Insulation resistance R from the outside of main negative relay S2 to reference potential terminal GN2(ii) a Insulation resistance RP1、RN1、RP2、RN2Are schematically drawn virtual resistors.
The following description will be given taking a sine wave signal with a low frequency as an example of the ac voltage signal generated by the signal generator DDS.
As is known to those skilled in the art, the DC Link capacitor Cx is an X capacitor connected between the outer side of the main positive relay S1 and the outer side of the main negative relay S2 of the electric vehicle, and has a very large capacitance value, and when the signal generator DDS outputs a low-frequency sine wave signal, the outer side of the main positive relay S1 and the outer side of the main negative relay S2 are equivalent to a short circuit; thus, the detection circuit diagram in fig. 2 may be equivalent to the circuit shown in fig. 4; let the amplitude of the ac voltage signal (i.e. the first voltage signal) output by the signal generator DDS be U1The amplitude of the second voltage signal is U2Based on the circuit principle, the first voltage signal and the second voltage signal are sine wave signals with the same frequency w; expressing the phase shift of the second voltage signal relative to the first voltage signal by θ, the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE001
（1）
wherein Z is1Represents RNP2The total impedance of the first capacitor C1, and the outside resistance detection value RNP2= RN2//RP2The following formula can be obtained:
Figure DEST_PATH_IMAGE002
（2）
the outer resistance detection value R can be calculated by the simultaneous equations (1) and (2)NP2：
Figure DEST_PATH_IMAGE003
。
Compared with the prior art, the controller can control the signal generator to output an alternating voltage signal, collect a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor, obtain a parallel value of an outer insulation resistor of the second end of the first switch module and an outer insulation resistor of the second end of the second switch module according to the first voltage signal and the second voltage signal, record the parallel value as an outer resistance detection value, and the outer resistance detection value can represent outer insulation performance of the first switch module and the second switch module; namely, before the first switch module and the second switch module are not closed, the outer side insulation performance of the first switch module and the second switch module can be estimated in advance, the first switch module and the second switch module are prevented from being closed when the outer side insulation performance fails, and the electric shock risk of high-voltage electrification is reduced as much as possible; meanwhile, the fault of the detection circuit can be conveniently found in time, and the short circuit of the battery pack is avoided.
A second embodiment of the present invention relates to a detection circuit, which is an improvement of the first embodiment, and is mainly improved in that: the detection circuit further comprises a plurality of sampling branches;
in this embodiment, referring to fig. 5, the plurality of sampling branches includes a first sampling branch and a second sampling branch; each sampling circuit at least comprises a third switch module and a second resistor which are connected with each other, and the controller 1 is connected to the control end of the third switch module of each sampling branch circuit and used for controlling the on and off of each third switch module. It should be noted that, in this embodiment and the following embodiments, the first sampling branch includes the switch module S31 and the resistor R21, and the second sampling branch includes the switch module S32 and the resistor R22.
The second end of the first capacitor C1 of the detection module 5 is connected to the second end of the main negative relay S2 through a first sampling branch, the first end of the main positive relay S1 is connected to the connection between the detection module 5 and the first sampling branch, and the second end of the main positive relay S1 is further connected to the first end of the main negative relay S2 through a second sampling branch. In one example, the second terminal of the first capacitor C1 is connected to one terminal of the resistor R21, the other terminal of the resistor R21 is connected to one terminal of the switch module S31, and the other terminal of the switch module S31 is connected to the second terminal of the main negative relay S2; the second terminal of the main positive relay S1 is connected to one terminal of the switch module S32, the switch module S32 is connected to one terminal of the resistor R22, and the other terminal of the resistor R22 is connected to a first terminal of the main negative relay S2.
In this embodiment, the controller 1 is further configured to control the third switch module in each sampling branch to be in an off state, and respectively collect a third voltage signal at the first end of the first resistor R1 and a fourth voltage signal at the second end of the first resistor R1, and obtain an inner-side resistance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side resistance detection value is an inner-side insulation resistor R at the first end of the main positive relay S1P1Inner insulation resistance R with first end of main negative relay S2N1Parallel value of (1), inner side resistance detection value RNP1= RN1//RP1. Note that, the controller 1 of the present embodiment may collect the third voltage signal and the fourth voltage signal by the first sampling circuit 61 and the second sampling circuit 62.
In this embodiment, the controller 1 is configured to control the third switch module in each sampling branch to be in a closed state, collect the first voltage signal and the second voltage signal respectively, and obtain the outer resistance detection value R according to at least the first voltage signal, the second voltage signal, and the resistance value of the second resistorNP2。
Next, how to calculate the inner resistance detection value and the outer resistance detection value of the main positive relay S1 and the main negative relay S2 in this embodiment will be described in detail by taking a sine wave signal with a low frequency as an example of the ac voltage signal generated by the signal generator DDS.
When the electric automobile is electrified at low voltage, the controller 1 enters a working state, the controller 1 controls the signal generator DDS to send out a low-frequency sine wave signal, controls the switch module S31 and the switch module S32 to be in an off state, and then respectively collects a third voltage signal of a first end (point A) of the first resistor R1 and a fourth voltage signal of a second end (point B) of the first resistor R1And the voltage signal can be used for obtaining the inner resistance detection value according to the third voltage signal and the fourth voltage signal. Here, since the internal resistance of the battery pack 2 is very small with respect to the internal insulation resistance of the main positive relay S1 and the main negative relay S2, the battery pack 2 can be considered as a short circuit, and the detection circuit of fig. 5 can be equivalent to the circuit shown in fig. 6; let the amplitude of the ac voltage signal (i.e. the third voltage signal) output by the signal generator DDS be U1The amplitude of the fourth voltage signal is U3Based on the circuit principle, the third voltage signal and the fourth voltage signal are sine wave signals with the same frequency w, the phase shift of the fourth voltage signal relative to the third voltage signal is represented by α, and the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE004
（3）
wherein Z is2Represents RNP1The total impedance of the first capacitor C1, and the inner resistance detection value RNP1= RN1//RP1The following formula can be obtained:
Figure DEST_PATH_IMAGE005
（4）
the inner resistance detection value R can be calculated by the simultaneous equations (3) and (4)NP1。
Then, the controller 1 controls the switch module S31 and the switch module S32 to be in a closed state, and respectively collects a first voltage signal at a first end (point a) of the first resistor R1 and a second voltage signal at a second end (point B) of the first resistor R1, so as to obtain an outside resistor detection value R according to the first voltage signal, the second voltage signal and a resistance value of the second resistorNP2. The DCLink capacitor Cx is an X capacitor connected between the outer side of the main positive relay S1 and the outer side of the main negative relay S2 of the electric vehicle, has a very large capacitance value, and when the signal generator DDS outputs a low-frequency sine wave signal, the outer side of the main positive relay S1 and the outer side of the main negative relay S2 are equivalent to short circuits; thus, the detection circuit diagram in FIG. 5 mayTo be equivalent to the circuit shown in fig. 7; wherein Rx = (R21 + R22)/2.
In one example, the controller 1 obtains an outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor; specifically, the controller 1 first determines whether the inner-side resistance detection value matches a preset resistance threshold value, for example, determines whether an absolute value of a difference between the inner-side resistance detection value and the resistance threshold value is smaller than a preset range, and determines that the inner-side resistance detection value does not match the preset resistance threshold value when the absolute value of the difference between the inner-side resistance detection value and the resistance threshold value is outside the preset range; and when the absolute value of the difference value between the inner side resistance detection value and the resistance threshold value is within a preset range, judging that the inner side resistance detection value is matched with the preset resistance threshold value.
When the controller 1 judges that the inner resistance detection value is not matched with the preset resistance threshold value, the inner resistance detection value R is determinedNP1The first voltage signal, the second voltage signal and the resistance value of the second resistor, and calculating the detection value R of the outer resistorNP2The specific calculation process is as follows:
let the amplitude of the ac voltage signal (i.e. the first voltage signal) output by the signal generator DDS be U1The amplitude of the second voltage signal is U2Based on the circuit principle, the first voltage signal and the second voltage signal are sine wave signals with the same frequency w; expressing the phase shift of the second voltage signal relative to the first voltage signal by θ, the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE006
（5）
wherein Z is3Represents R in parallelNP1And (Rx + R)NP2) And the total impedance of the first capacitor C1, the outer resistance detection value RNP2= RN2//RP2The following formula can be obtained:
Figure DEST_PATH_IMAGE007
（6）
the outer resistance detection value R can be calculated by the simultaneous equations (5) and (6)NP2。
When the controller 1 judges that the inner resistance detection value is matched with the preset resistance threshold value, the outer resistance detection value R is calculated according to the first voltage signal, the second voltage signal and the resistance value of the second resistorNP2The specific calculation process is as follows: due to the inner insulation resistance RNP1Matching a predetermined resistance threshold, i.e. RNP1Sufficiently large, the circuit shown in fig. 7 may be equivalent to the circuit shown in fig. 8, and the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE008
（7）
wherein Z is4Represents RNP2Rx and the total impedance of the first capacitor C1, and the outside resistance detection value RNP2= RN2//RP2The following formula can be obtained:
Figure DEST_PATH_IMAGE009
（8）
the outer resistance detection value R can be calculated by the simultaneous equations (7) and (8)NP2。
Compared with the first embodiment, the present embodiment can detect the inner resistance detection value and the outer resistance detection value of the first switch module and the second switch module simultaneously, so as to determine the insulation performance of the first switch module and the second switch module more accurately.
A third embodiment of the present invention relates to a detection circuit, which is an improvement of the second embodiment, and the main improvements are: the detection circuit further includes a plurality of Y capacitors.
The first terminal of the main positive relay S1 and the first terminal of the main negative relay S2 are connected to a reference potential terminal G through different Y capacitors, respectively; it should be noted that the second terminal of the main positive relay S1 and the second terminal of the main negative relay S2 may also be connected to the reference potential terminal G through different Y capacitors, respectively, and in this embodiment and the following embodiments, the second terminal of the main positive relay S1 and the second terminal of the main negative relay S2 are connected to the reference potential terminal G through different Y capacitors, respectively.
Referring to fig. 9, a first terminal of the main positive relay S1 passes through the Y capacitor CP1Connected to a reference potential terminal G, a second terminal of the main positive relay S1 via a Y capacitor CP2Connected to a reference potential terminal G, a first terminal of a main negative relay S2 is connected through a Y capacitor CN1Connected to a reference potential terminal G, a second terminal of the main negative relay S2 via a Y capacitor CN2Connected to a reference potential terminal G.
The controller 1 is specifically configured to obtain an inner-side resistance detection value and an inner-side capacitance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side capacitance detection value is a Y-capacitor C connected to the first end of the main positive relay S1P1And a Y capacitor C connected with a first end of the main negative relay S2N1Parallel value of (1), inner side capacitance detection value CNP1= CN1//CP1(ii) a And based on the inner resistance detection value RNP1Inner side capacitance detection value CNP1Obtaining the resistance value of the first voltage signal, the second voltage signal and the second resistor to obtain the detection value R of the outer resistorNP2。
Next, how to calculate the insulation resistance of the main positive relay S1 and the main negative relay S2 in this embodiment will be described in detail by taking a sine wave signal with a low frequency as an example of the ac voltage signal emitted by the signal generator DDS.
When the electric automobile is powered on at a low voltage, the controller 1 enters a working state, the controller 1 controls the signal generator DDS to send out a low-frequency sine wave signal, the switch module S31 and the switch module S32 are controlled to be in an off state, then a third voltage signal of a first end (point A) of the first resistor R1 and a fourth voltage signal of a second end (point B) of the first resistor R1 are respectively collected, and then an inner side resistor detection value can be obtained according to the third voltage signal and the fourth voltage signal. However, since the internal resistance of the battery pack 2 is very small with respect to the internal insulation resistance of the main positive relay S1 and the main negative relay S2, the battery pack 2 can be considered as a short circuit, and the detection circuit of fig. 9 can be equivalent to the detection circuit of fig. 9The circuit shown in FIG. 10; let the amplitude of the ac voltage signal (i.e. the third voltage signal) output by the signal generator DDS be U1The amplitude of the fourth voltage signal is U3Based on the circuit principle, the third voltage signal and the fourth voltage signal are sine wave signals with the same frequency w, the phase shift of the fourth voltage signal relative to the third voltage signal is represented by α, and the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE010
（9）
wherein Z is5Represents R in parallelNP1And CNP1And the total impedance of the first capacitor C1, the inner resistance detection value RNP1=RN1//RP1The following formula can be obtained:
Figure DEST_PATH_IMAGE011
（10）
based on equations (9) (10), it is possible to obtain:
Figure DEST_PATH_IMAGE012
（11）
the parallel calculation formula of the resistor and the capacitor can be obtained:
Figure DEST_PATH_IMAGE013
（12）
by simultaneous equations (11) and (12), C can be obtainedNP1、RNP1。
In one example, the controller 1 is configured to detect the value R based on the inner resistanceNP1Inner side capacitance detection value CNP1Obtaining the resistance value of the first voltage signal, the second voltage signal and the second resistor to obtain the detection value R of the outer resistorNP2(ii) a Specifically, the controller 1 first determines whether the inner-side resistance detection value matches a preset resistance threshold value, and whether the inner-side capacitance detection value matches a preset capacitance threshold value; for example, when the inside isWhen the absolute value of the difference value between the inner side resistance detection value and the resistance threshold value is within the preset range, judging that the inner side resistance detection value is matched with the preset resistance threshold value; when the absolute value of the difference value between the inner side capacitance detection value and the capacitance threshold value is out of the preset range, the inner side capacitance detection value is judged to be not matched with the preset capacitance threshold value, and when the absolute value of the difference value between the inner side capacitance detection value and the capacitance threshold value is in the preset range, the inner side capacitance detection value is judged to be matched with the preset capacitance threshold value.
The controller 1 determines the inner resistance detection value RNP1Mismatch with a predetermined resistance threshold, and/or inner capacitance detection value CNP1When the resistance value is not matched with the preset capacitance threshold value, the resistance value R is detected according to the inner side resistanceNP1Inner side capacitance detection value CNP1A first voltage signal and a second voltage signal, calculating an outer resistance detection value RNP2The specific calculation process is as follows:
the DC Link capacitance Cx is an X capacitance connected between the outer side of the main positive relay S1 and the outer side of the main negative relay S2 of the electric vehicle, and has a very large capacitance value, and when the signal generator DDS outputs a low-frequency sine wave signal, the outer side of the main positive relay S1 and the outer side of the main negative relay S2 are equivalent to a short circuit, and therefore, the detection circuit diagram in fig. 9 may be equivalent to a circuit as shown in fig. 11.
Let the amplitude of the ac voltage signal (i.e. the first voltage signal) output by the signal generator DDS be U1The amplitude of the second voltage signal is U2Based on the circuit principle, the first voltage signal and the second voltage signal are sine wave signals with the same frequency w; expressing the phase shift of the second voltage signal relative to the first voltage signal by θ, the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE014
（13）
wherein Z is6Represents R in parallelNP1、CNP1、Rx、RNP2、CNP2And the total impedance of the first capacitor C1, the outer resistance detection value RNP2= RN2//RP2The following formula can be obtained:
Figure DEST_PATH_IMAGE015
（14）
based on the equations (13) (14), it can be found that:
Figure DEST_PATH_IMAGE016
（15）
the parallel calculation formula of the resistor and the capacitor can be obtained:
Figure DEST_PATH_IMAGE017
（16）
by simultaneous equations (15) and (16), C can be obtainedNP2、RNP2。
The controller 1 determines the inner resistance detection value RNP1Matched with a preset resistance threshold value and the inner side capacitance detection value CNP1When the resistance value of the outer resistor is matched with the preset capacitance threshold value, the outer resistor detection value R is calculated according to the first voltage signal, the second voltage signal and the resistance value of the second resistorNP2The specific calculation process is as follows: due to the inner insulation resistance RNP1Matched with a preset resistance threshold value and the inner side capacitance detection value CNP1Matching a predetermined capacitance threshold, i.e. RNP1Is large enough, CNP1Sufficiently small, the circuit shown in fig. 11 may be equivalent to the circuit shown in fig. 12, and the following formula can be obtained based on kirchhoff's law:
Figure DEST_PATH_IMAGE018
（17）
wherein Z is7Represents RNP2Rx and the total impedance of the first capacitor C1, and the outside resistance detection value RNP2= RN2//RP2The following formula can be obtained:
Figure DEST_PATH_IMAGE019
（18）
the simultaneous above formulas (17) and (18) can yield:
Figure DEST_PATH_IMAGE020
（19）
the parallel calculation formula of the resistor and the capacitor can be obtained:
Figure DEST_PATH_IMAGE021
（20）
by simultaneous equations (19) and (20), C can be obtainedNP2、RNP2。
In the present embodiment, the detection circuit including the Y capacitor can simultaneously detect the inner resistance detection value and the outer resistance detection value of the first switch block and the second switch block, as compared to the second embodiment.
A fourth embodiment of the present invention provides a detection method applied to a controller of a detection circuit in a first embodiment, please refer to fig. 1 to 4.
Fig. 13 shows a specific flow of the detection method according to the present embodiment.
Step 101, controlling a signal generator to output an alternating voltage signal.
Specifically, when the electric vehicle is powered on at low voltage, the controller 1 (which may be a battery management system) enters an operating state, and the main positive relay S1 and the main negative relay S2 in the electric vehicle are both in an off state, and the controller 1 controls the signal generator DDS to output an alternating voltage signal.
Step 102, respectively collecting a first voltage signal of a first end of a first resistor and a second voltage signal of a second end of the first resistor.
Specifically, after the signal generator DDS outputs the ac voltage signal, the controller 1 collects a first voltage signal of a first end (i.e., a point a in fig. 2) of the first resistor R1 with respect to the reference potential end G, where the first voltage signal is the ac voltage signal, and collects a second voltage signal of a second end (i.e., a point B in fig. 2) of the first resistor R1 with respect to the reference potential end G.
And 103, obtaining an outer resistance detection value at least according to the first voltage signal and the second voltage signal.
Specifically, the controller 1 obtains a parallel connection value of the outer insulation resistance of the second terminal of the main positive relay S1 and the outer insulation resistance of the second terminal of the main negative relay S2 from the first voltage signal and the second voltage signal according to the voltage division principle of the first resistor R1 in the detection circuit.
Since the first embodiment corresponds to the present embodiment, the present embodiment can be implemented in cooperation with the first embodiment. The related technical details mentioned in the first embodiment are still valid in this embodiment, and the technical effects that can be achieved in the first embodiment can also be achieved in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the first embodiment.
Compared with the prior art, the controller can control the signal generator to output an alternating voltage signal, collect a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor, obtain a parallel value of an outer insulation resistor of the second end of the first switch module and an outer insulation resistor of the second end of the second switch module according to the first voltage signal and the second voltage signal, record the parallel value as an outer resistance detection value, and the outer resistance detection value can represent outer insulation performance of the first switch module and the second switch module; namely, before the first switch module and the second switch module are not closed, the outer side insulation performance of the first switch module and the second switch module can be estimated in advance, the first switch module and the second switch module are prevented from being closed when the outer side insulation performance fails, and the electric shock risk of high-voltage electrification is reduced as much as possible; meanwhile, the fault of the detection circuit can be conveniently found in time, and the short circuit of the battery pack is avoided.
A fifth embodiment of the present invention relates to a detection method, and is different from the fourth embodiment mainly in that: the inner resistance detection value and the outer resistance detection value of the first switch module and the second switch module can be detected simultaneously. Referring to fig. 5 to 8, the detection method of the present embodiment is applied to the detection circuit of the second embodiment.
The specific flow of the detection method of the present embodiment is shown in fig. 14.
Step 201, controlling the third switch module in each sampling branch to be in an off state, and respectively collecting a third voltage signal at the first end of the first resistor and a fourth voltage signal at the second end of the first resistor.
Specifically, when the electric vehicle is powered on at a low voltage, the controller 1 enters a working state, the controller 1 controls the signal generator DDS to send out a low-frequency sine wave signal, controls the switch module S31 and the switch module S32 to be in an off state, and then collects a third voltage signal at the first end (point a) of the first resistor R1 and a fourth voltage signal at the second end (point B) of the first resistor R1 respectively.
Step 202, obtaining an inner resistance detection value according to the third voltage signal and the fourth voltage signal.
Specifically, the controller 1 obtains the inner insulation resistance R of the first end of the main positive relay S1 from the third voltage signal and the fourth voltage signalP1Inner insulation resistance R with first end of main negative relay S2N1The parallel value of (a) is the inner side resistance detection value.
Step 203, controlling the third switch module in each sampling branch to be in a closed state, and respectively collecting the first voltage signal and the second voltage signal.
Specifically, the controller 1 is configured to control the third switch modules in all the sampling branches to be in a closed state, and collect the first voltage signal and the second voltage signal respectively.
Step 204, obtaining an outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor, and including the following substeps:
in sub-step 2041, when it is determined that the inner resistance detection value matches the preset resistance threshold value, the outer resistance detection value is calculated according to the first voltage signal, the second voltage signal, and the resistance value of the second resistor.
And a substep 2042 of calculating the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor when the inner resistance detection value is judged not to match the preset resistance threshold value.
Specifically, the controller 1 obtains an outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor; specifically, the controller 1 first determines whether the inner-side resistance detection value matches a preset resistance threshold value, for example, determines whether an absolute value of a difference between the inner-side resistance detection value and the resistance threshold value is smaller than a preset range, and determines that the inner-side resistance detection value does not match the preset resistance threshold value when the absolute value of the difference between the inner-side resistance detection value and the resistance threshold value is outside the preset range; and when the absolute value of the difference value between the inner side resistance detection value and the resistance threshold value is within a preset range, judging that the inner side resistance detection value is matched with the preset resistance threshold value.
When the controller 1 judges that the inner resistance detection value is not matched with the preset resistance threshold value, the inner resistance detection value R is determinedNP1The first voltage signal, the second voltage signal and the resistance value of the second resistor, and calculating the detection value R of the outer resistorNP2。
When the controller 1 judges that the inner resistance detection value is matched with the preset resistance threshold value, the outer resistance detection value R is calculated according to the first voltage signal, the second voltage signal and the resistance value of the second resistorNP2。
Since the second embodiment corresponds to the present embodiment, the present embodiment can be implemented in cooperation with the second embodiment. The related technical details mentioned in the second embodiment are still valid in this embodiment, and the technical effects that can be achieved in the second embodiment can also be achieved in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the second embodiment.
Compared with the fourth embodiment, the present embodiment can detect the inner resistance detection value and the outer resistance detection value of the first switch module and the second switch module simultaneously, so as to determine the insulation performance of the first switch module and the second switch module more accurately.
A sixth embodiment of the present invention relates to a detection method, and is mainly different from the fifth embodiment in that: for a detection circuit comprising a Y capacitor, the inner resistance detection value and the outer resistance detection value of the first switch module and the second switch module can be detected simultaneously. Referring to fig. 9 to 12, the detection method of the present embodiment is applied to the detection circuit of the third embodiment.
The specific flow of the detection method of the present embodiment is shown in fig. 15.
Step 301, controlling the third switch module in each sampling branch to be in an off state, and respectively collecting a third voltage signal at the first end of the first resistor and a fourth voltage signal at the second end of the first resistor.
Specifically, when the electric vehicle is powered on at a low voltage, the controller 1 enters a working state, the controller 1 controls the signal generator DDS to send out a low-frequency sine wave signal, controls the switch module S31 and the switch module S32 to be in an off state, and then collects a third voltage signal at the first end (point a) of the first resistor R1 and a fourth voltage signal at the second end (point B) of the first resistor R1 respectively.
Step 302, an inner resistance detection value and an inner capacitance detection value are obtained according to the third voltage signal and the fourth voltage signal.
Specifically, the controller 1 obtains an inner resistance detection value and an inner capacitance detection value, which is the Y-capacitor C connected to the first end of the main positive relay S1, from the third voltage signal and the fourth voltage signalP1And a Y capacitor C connected with a first end of the main negative relay S2N1Parallel value of (1), inner side capacitance detection value CNP1= CN1//CP1。
Step 303, controlling the third switch module in each sampling branch to be in a closed state, and respectively collecting the first voltage signal and the second voltage signal.
Specifically, the controller 1 is configured to control the third switch module in each sampling branch to be in a closed state, and collect the first voltage signal and the second voltage signal respectively.
Step 304, obtaining an outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor, and comprising the following substeps:
in sub-step 3041, when it is determined that the inner-side resistance detection value matches the preset resistance threshold and the inner-side capacitance detection value matches the preset capacitance threshold, the outer-side resistance detection value is calculated according to the first voltage signal, the second voltage signal, and the resistance of the second resistor.
In sub-step 3042, when it is determined that the inner resistance detection value does not match the preset resistance threshold and/or the inner capacitance detection value does not match the preset capacitance threshold, the outer resistance detection value is calculated according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal and the second voltage signal.
Specifically, the controller 1 is configured to detect the value R based on the inner resistanceNP1Inner side capacitance detection value CNP1Obtaining the resistance value of the first voltage signal, the second voltage signal and the second resistor to obtain the detection value R of the outer resistorNP2(ii) a Specifically, the controller 1 first determines whether the inner-side resistance detection value matches a preset resistance threshold value, and whether the inner-side capacitance detection value matches a preset capacitance threshold value; for example, when the absolute value of the difference between the inner-side resistance detection value and the resistance threshold value is outside a preset range, it is determined that the inner-side resistance detection value does not match the preset resistance threshold value, and when the absolute value of the difference between the inner-side resistance detection value and the resistance threshold value is within the preset range, it is determined that the inner-side resistance detection value matches the preset resistance threshold value; when the absolute value of the difference value between the inner side capacitance detection value and the capacitance threshold value is out of the preset range, the inner side capacitance detection value is judged not to be matched with the preset capacitance threshold value, and when the absolute value of the difference value between the inner side capacitance detection value and the capacitance threshold value is in the preset range, the inner side capacitance detection value is judgedThe measured value is matched to a predetermined capacitance threshold.
The controller 1 determines the inner resistance detection value RNP1Mismatch with a predetermined resistance threshold, and/or inner capacitance detection value CNP1When the resistance value is not matched with the preset capacitance threshold value, the resistance value R is detected according to the inner side resistanceNP1Inner side capacitance detection value CNP1A first voltage signal and a second voltage signal, calculating an outer resistance detection value RNP2。
The controller 1 determines the inner resistance detection value RNP1Matched with a preset resistance threshold value and the inner side capacitance detection value CNP1When the resistance value of the outer resistor is matched with the preset capacitance threshold value, the outer resistor detection value R is calculated according to the first voltage signal, the second voltage signal and the resistance value of the second resistorNP2。
Since the third embodiment corresponds to the present embodiment, the present embodiment can be implemented in cooperation with the third embodiment. The related technical details mentioned in the third embodiment are still valid in this embodiment, and the technical effects that can be achieved in the third embodiment can also be achieved in this embodiment, and are not described herein again in order to reduce repetition. Accordingly, the related-art details mentioned in the present embodiment can also be applied to the third embodiment.
In the present embodiment, the detection circuit including the Y capacitor can simultaneously detect the inner resistance detection value and the outer resistance detection value of the first switch block and the second switch block, as compared with the fifth embodiment.
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.

Claims (10)

1. A detection circuit, comprising: the device comprises a controller, a battery pack, a first switch module, a second switch module, a DCLink capacitor and a detection module;
two ends of the battery pack are respectively connected to a first end of the first switch module and a first end of the second switch module, and a second end of the first switch module is connected to a second end of the second switch module through the DCLink capacitor; the first end of the detection module is connected to a reference potential end, and the second end of the detection module is connected to the second end of the second switch module;
the detection module comprises a signal generator, a first resistor and a first capacitor, wherein a first end of the signal generator forms a first end of the detection module, a second end of the signal generator is connected to a first end of the first resistor, a second end of the first resistor is connected to a first end of the first capacitor, and a second end of the first capacitor forms a second end of the detection module; the controller is connected to the signal generator;
the controller is used for controlling the signal generator to output an alternating voltage signal;
the controller is used for respectively acquiring a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor;
the controller is further configured to obtain an outer resistance detection value at least according to the first voltage signal and the second voltage signal, where the outer resistance detection value is a parallel connection value of an outer insulation resistance of the second end of the first switch module and an outer insulation resistance of the second end of the second switch module.
2. The detection circuit according to claim 1, further comprising a plurality of sampling branches, each of the sampling branches comprising at least a third switching module and a second resistor connected to each other, the plurality of sampling branches comprising a first sampling branch and a second sampling branch;
the second end of the detection module is connected to the second end of the second switch module through the first sampling branch, the first end of the first switch module is connected to the connection position of the detection module and the first sampling branch, and the second end of the first switch module is also connected to the first end of the second switch module through the second sampling branch;
the controller is specifically configured to control the third switch module in each sampling branch to be in a closed state, and collect the first voltage signal and the second voltage signal respectively;
the controller is specifically configured to obtain the outer resistance detection value at least according to the first voltage signal, the second voltage signal, and the resistance value of the second resistor;
the controller is further configured to control the third switch modules in the sampling branches to be in an off state, and respectively collect a third voltage signal at the first end of the first resistor and a fourth voltage signal at the second end of the first resistor;
the controller is further configured to obtain an inner-side resistance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side resistance detection value is a parallel connection value of an inner-side insulation resistance of the first end of the first switch module and an inner-side insulation resistance of the first end of the second switch module.
3. The detection circuit of claim 2, further comprising: a plurality of Y capacitors; the first end of the first switch module and the first end of the second switch module are respectively connected to the reference potential end through different Y capacitors;
the controller is specifically configured to obtain the inner-side resistance detection value and an inner-side capacitance detection value according to the third voltage signal and the fourth voltage signal, where the inner-side capacitance detection value is a parallel connection value of the Y capacitor connected to the first end of the first switch module and the Y capacitor connected to the first end of the second switch module;
the controller is used for obtaining the outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor.
4. The detection circuit according to claim 2, wherein the controller is specifically configured to obtain the outer resistance detection value based on the inner resistance detection value, the first voltage signal, the second voltage signal, and the resistance value of the second resistor.
5. The detection circuit of claim 3, wherein the controller is configured to calculate the outer resistance detection value according to the first voltage signal, the second voltage signal, and the resistance value of the second resistor when it is determined that the inner resistance detection value matches a preset resistance threshold value and the inner capacitance detection value matches a preset capacitance threshold value;
the controller is configured to calculate the outer resistance detection value according to the inner resistance detection value, the inner capacitance detection value, the first voltage signal, and the second voltage signal when it is determined that the inner resistance detection value is not matched with a preset resistance threshold value and/or the inner capacitance detection value is not matched with a preset capacitance threshold value.
6. The detection circuit according to claim 4, wherein the controller is configured to calculate the outer resistance detection value based on the first voltage signal, the second voltage signal, and the resistance value of the second resistor when determining that the inner resistance detection value matches a preset resistance threshold value;
the controller is used for calculating the outer resistance detection value according to the inner resistance detection value, the first voltage signal, the second voltage signal and the resistance value of the second resistor when the inner resistance detection value is judged not to be matched with a preset resistance threshold value.
7. The detection circuit of claim 3, further comprising a plurality of sampling circuits connected to the controller, the plurality of sampling circuits comprising a first sampling circuit, a second sampling circuit;
the controller is specifically configured to acquire, by the first sampling circuit, a first voltage signal at a first end of the first resistor, and acquire, by the second sampling circuit, a second voltage signal at a second end of the first resistor.
8. The detection circuit of claim 7, wherein each of the sampling circuits comprises a third resistor, a second capacitor, a voltage follower, and a sampling unit; the controller is connected to the sampling unit of the sampling circuit;
the first end of the third resistor is the input end of the sampling circuit, and the second end of the third resistor is connected to the reference potential end through the second capacitor; the first input end of the voltage follower is connected with the junction of the third resistor and the second capacitor, the second input end of the voltage follower is connected with the output end of the voltage follower, the output end of the voltage follower is further connected with one end of the sampling unit, and the other end of the sampling unit is connected with the controller.
9. The detection method is characterized by being applied to a controller of a detection circuit, wherein the detection circuit further comprises a battery pack, a first switch module, a second switch module, a DCLink capacitor and a detection module, and the detection module comprises a signal generator, a first resistor and a first capacitor; the method comprises the following steps:
controlling the signal generator to output an alternating voltage signal;
respectively acquiring a first voltage signal of a first end of the first resistor and a second voltage signal of a second end of the first resistor;
and obtaining an outer resistance detection value according to at least the first voltage signal and the second voltage signal, wherein the outer resistance detection value is a parallel connection value of an outer insulation resistance of the second end of the first switch module and an outer insulation resistance of the second end of the second switch module.
10. The detection method according to claim 9, wherein the detection circuit further comprises a plurality of sampling branches, each of the sampling branches comprising at least a third switching module and a second resistor connected to each other, the plurality of sampling branches comprising a first sampling branch and a second sampling branch; the method further comprises the following steps:
controlling the third switch module in each sampling branch circuit to be in an off state, and respectively collecting a third voltage signal of the first end of the first resistor and a fourth voltage signal of the second end of the first resistor;
obtaining an inner resistance detection value according to the third voltage signal and the fourth voltage signal, wherein the inner resistance detection value is a parallel connection value of an inner insulation resistance of the first end of the first switch module and an inner insulation resistance of the first end of the second switch module;
the method comprises the following steps of respectively collecting a first voltage signal of a first end of a first resistor and a second voltage signal of a second end of the first resistor, and specifically:
controlling the third switch module in each sampling branch circuit to be in a closed state, and respectively collecting the first voltage signal and the second voltage signal;
the obtaining of the outside resistance detection value at least according to the first voltage signal and the second voltage signal specifically includes:
and obtaining the detection value of the outer resistor at least according to the first voltage signal, the second voltage signal and the resistance value of the second resistor.
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WO2008016179A1 (en) * 2006-08-04 2008-02-07 Toyota Jidosha Kabushiki Kaisha Insulation resistance determining system, insulation resistance determining apparatus and insulation resistance determining method
US20090108850A1 (en) * 2007-10-01 2009-04-30 Tomohiro Yamagami Insulation resistance decrease detector for industrial vehicle
CN103076497A (en) * 2012-12-18 2013-05-01 江苏常隆客车有限公司 Insulation detection method based on low frequency impulse signal injection
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