CN110967560A - Insulation detection circuit, insulation detection method and battery management system - Google Patents

Insulation detection circuit, insulation detection method and battery management system Download PDF

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Publication number
CN110967560A
CN110967560A CN201910156503.0A CN201910156503A CN110967560A CN 110967560 A CN110967560 A CN 110967560A CN 201910156503 A CN201910156503 A CN 201910156503A CN 110967560 A CN110967560 A CN 110967560A
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China
Prior art keywords
voltage
resistance value
module
battery pack
tested
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CN201910156503.0A
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Inventor
李盟
但志敏
张伟
侯贻真
孙卫平
李前邓
刘昌鑑
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Contemporary Amperex Technology Co Ltd
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Contemporary Amperex Technology Co Ltd
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Priority to CN201910156503.0A priority Critical patent/CN110967560A/en
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/16Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
    • G01R27/18Measuring resistance to earth, i.e. line to ground
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01RMEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/36Arrangements for testing, measuring or monitoring the electrical condition of accumulators or electric batteries, e.g. capacity or state of charge [SoC]
    • G01R31/3644Constructional arrangements

Abstract

The invention discloses an insulation detection circuit, a detection method and a battery management system, wherein the insulation detection circuit comprises: the device comprises a first switch module, a first voltage division module, a second voltage division module, an isolation module, a third voltage division module, a signal generator and a processor; the first switch module, the first voltage division module and the second voltage division module are arranged between the anode of the battery pack to be tested and a reference voltage end in series; the isolation module, the third voltage division module and the signal generator are arranged between the anode of the battery pack to be tested and the reference voltage end in series. By adopting the embodiment of the invention, the insulation resistance value of the anode high-voltage circuit at the side of the battery pack to be tested relative to the reference voltage end and the insulation resistance value of the cathode high-voltage circuit at the side of the battery pack to be tested relative to the reference voltage end can be separately detected, so that the independent alarm of high-voltage positive ground pressure reduction and high-voltage negative ground pressure can be realized, and the risk of false alarm can be avoided.

Description

Insulation detection circuit, insulation detection method and battery management system
Technical Field
The invention relates to the technical field of batteries, in particular to an insulation detection circuit, an insulation detection method and a battery management system.
Background
The battery pack is responsible for providing electric energy for a motor of the electric automobile and is connected with a load through the positive pole switch module and the negative pole switch module respectively. Since the safety of the high voltage electricity of the battery pack, which is one of the key components of the electric vehicle, is the primary consideration of the power battery system, it is important to detect the insulation performance of the electric vehicle as an essential part of the design, that is, to detect and issue an early warning of an insulation abnormality in advance.
At present, insulation detection is mainly performed on a battery pack based on an alternating current injection method or a voltage division method, but the alternating current injection method or the voltage division method can only detect parallel connection values of insulation resistance values of a whole vehicle high-voltage positive low-voltage ground and a high-voltage negative low-voltage ground, when the insulation resistance value of the whole vehicle high-voltage positive low-voltage ground is lower and the insulation resistance value of the high-voltage negative low-voltage ground is lower at the same time, the insulation resistance values of the high-voltage positive low-voltage ground and the high-voltage negative low-voltage ground are possibly greater than an alarm threshold value, but the parallel connection values of the high-voltage positive.
Disclosure of Invention
The embodiment of the invention provides an insulation detection circuit, a detection method and a battery management system, which can independently detect the insulation resistance value of a positive electrode high-voltage circuit at the side of a battery pack to be detected relative to a reference voltage end and the insulation resistance value of a negative electrode high-voltage circuit at the side of the battery pack to be detected relative to the reference voltage end, so that the independent alarm of high-voltage positive ground pressure and low-voltage negative ground can be realized, and the risk of false alarm is avoided.
In a first aspect, an embodiment of the present invention provides an insulation detection circuit, where the insulation detection circuit includes: the device comprises a first switch module, a first voltage division module, a second voltage division module, an isolation module, a third voltage division module, a signal generator and a processor; wherein the content of the first and second substances,
the first switch module, the first voltage division module and the second voltage division module are arranged between the anode of the battery pack to be tested and the reference voltage end in series;
the isolation module, the third voltage division module and the signal generator are arranged between the anode of the battery pack to be tested and the reference voltage end in series;
a first sampling point is arranged between the first voltage division module and the second voltage division module, a second sampling point is arranged between the isolation module and the third voltage division module, and a third sampling point is arranged between the third voltage division module and the signal generator;
the first sampling point is configured to provide a first sampling signal, the second sampling point is configured to provide a second sampling signal, and the third sampling point is configured to provide a third sampling signal;
the processor is configured to calculate an insulation resistance value of the positive electrode high-voltage circuit on the side where the battery pack to be tested is located relative to the reference voltage end and an insulation resistance value of the negative electrode high-voltage circuit on the side where the battery pack to be tested is located relative to the reference voltage end according to the first sampling signal, the second sampling signal and the third sampling signal.
In one possible implementation of the first aspect, the first switching module includes a first switching device, the first voltage divider module includes a first resistive network, the second voltage divider module includes a second resistive network, and the first sampling point is located between the first resistive network and the second resistive network.
In one possible implementation of the first aspect, the isolation module comprises a first capacitor, the third voltage division module comprises a third resistor network, the second sampling point is located between the first capacitor and the third resistor network, and the third sampling point is located between the third resistor network and the signal generator.
In one possible implementation of the first aspect, the insulation detection circuit further comprises a first voltage follower and a second voltage follower; the first input end of the first voltage follower is connected with the second sampling point, the second input end of the first voltage follower is connected with the output end of the first voltage follower, and the output end of the first voltage follower is also connected with the processor; the first input end of the second voltage follower is connected with the third sampling point, the second input end of the second voltage follower is connected with the output end of the second voltage follower, and the output end of the second voltage follower is further connected with the processor.
In one possible implementation of the first aspect, the insulation detection circuit further includes: the device comprises a first filtering module, a second filtering module and a third filtering module; the first end of the first filtering module is connected with the first sampling point, and the second end of the first filtering module is connected with the processor; the first end of the second filtering module is connected with the second sampling point, and the second end of the second filtering module is connected with the first input end of the first voltage follower; the first end of the third filtering module is connected with the third sampling point, and the second end of the third filtering module is connected with the first input end of the second voltage follower.
In one possible implementation of the first aspect, the insulation detection circuit further comprises a first voltage follower and a second voltage follower; the first input end of the first voltage follower is connected with the second sampling point, the second input end of the first voltage follower is connected with the output end of the first voltage follower, and the output end of the first voltage follower is also connected with the processor; the first input end of the second voltage follower is connected with the third sampling point, the second input end of the second voltage follower is connected with the output end of the second voltage follower, and the output end of the second voltage follower is further connected with the processor.
In a second aspect, embodiments of the present invention provide a battery management system, which includes the insulation detection circuit as described above.
In a third aspect, an embodiment of the present invention provides a detection method for an insulation detection circuit, where the detection method is used for the insulation detection circuit, and the detection method includes:
controlling an anode switch module positioned between an anode of the battery pack to be tested and a load to be switched off, a cathode switch module positioned between a cathode of the battery pack to be tested and the load to be switched off and a first switch module to be switched on, and obtaining a first sampling signal from a first sampling point;
controlling the anode switch module to be disconnected, the cathode switch module to be disconnected and the first switch module to be disconnected, obtaining a second sampling signal from a second sampling point and obtaining a third sampling signal from a third sampling point;
and calculating the insulation resistance value of the positive high-voltage circuit at the side of the battery pack to be tested relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit at the side of the battery pack to be tested relative to the reference voltage end according to the first sampling signal, the second sampling signal and the third sampling signal.
In a possible implementation manner of the second aspect, calculating an insulation resistance value of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and an insulation resistance value of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end according to the first sampling signal, the second sampling signal, and the third sampling signal includes: obtaining a first parallel resistance value according to the second sampling signal and the third sampling signal, wherein the first parallel resistance value is the parallel resistance value of the insulation resistance value of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end; and obtaining the insulation resistance value of the positive high-voltage circuit at the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit at the side where the battery pack to be tested is located relative to the reference voltage end according to the first sampling signal and the first parallel resistance value.
In one possible implementation of the second aspect, controlling the positive switch module to be turned off, the negative switch module to be turned off, the first switch module to be turned off, obtaining the second sampling signal from the second sampling point, and obtaining the third sampling signal from the third sampling point includes: controlling the positive switch module to be closed, the negative switch module to be closed, and the first switch module to be opened, obtaining a fourth sampling signal from the second sampling point, and obtaining a fifth sampling signal from the third sampling point; obtaining a second parallel resistance value according to the fourth sampling signal and the fifth sampling signal, wherein the second parallel resistance value is the insulation resistance value of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end, the insulation resistance value of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end, and the parallel resistance value of the insulation resistance values of the three-phase end of the whole vehicle; judging whether the second parallel resistance value is smaller than a first alarm threshold value or not; and if the second parallel resistance value is smaller than the first alarm threshold value, the anode switch module is controlled to be switched off, the cathode switch module is controlled to be switched off, the first switch module is controlled to be switched off, a second sampling signal is obtained from a second sampling point, and a third sampling signal is obtained from a third sampling point.
In one possible implementation of the second aspect, after obtaining the second sampled signal from the second sampled point and obtaining the third sampled signal from the third sampled point, the detection method further includes: obtaining a first parallel resistance value according to the second sampling signal and the third sampling signal, wherein the first parallel resistance value is the parallel resistance value of the insulation resistance value of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end; obtaining a third parallel resistance value according to the first parallel resistance value and the second parallel resistance value, wherein the third parallel resistance value is the parallel resistance value of the insulation resistance value of the whole vehicle three-phase end; if the third parallel resistance value is smaller than the second alarm threshold value, determining that the insulation resistance value of the three-phase end of the side where the load is located fails; and if the third parallel resistance value is larger than the second alarm threshold value, determining that the insulation resistance value of the side where the battery pack to be tested is located fails.
In the embodiment of the invention, an isolation module, a third voltage division module and a signal generator are arranged between the anode of the battery pack to be tested of the insulation detection circuit and a reference voltage end in series, and a first switch module, a first voltage division module and a second voltage division module are arranged in series. The processor can detect and obtain the insulation resistance value of the positive high-voltage circuit at the side of the battery pack to be detected relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit at the side of the battery pack to be detected relative to the reference voltage end, thereby realizing the independent alarm of high-voltage positive ground pressure and low-voltage negative ground pressure, and avoiding the occurrence of the risk of false alarm.
Different from the alternating current injection method in the prior art, because the insulation detection circuit in the embodiment of the invention is additionally provided with the first switch module, the first voltage division module and the second voltage division module, on the basis of obtaining the parallel resistance value of the insulation resistance value of the anode high-voltage circuit at the side where the battery pack to be detected is located relative to the reference voltage end and the insulation resistance value of the cathode high-voltage circuit at the side where the battery pack to be detected is located relative to the reference voltage end, the insulation resistance value of the anode high-voltage circuit at the side where the battery pack to be detected is located relative to the reference voltage end and the insulation resistance value of the cathode high-voltage circuit at the side where the battery pack to be detected is located relative to the reference voltage end can.
Drawings
The present invention will be better understood from the following description of specific embodiments thereof taken in conjunction with the accompanying drawings, in which like or similar reference characters designate like or similar features.
Fig. 1 is a schematic structural diagram of an insulation detection circuit according to an embodiment of the present invention;
fig. 2 is a schematic structural diagram of an insulation detection circuit according to another embodiment of the present invention;
fig. 3 is a schematic flow chart of a detection method of the insulation detection circuit according to an embodiment of the present invention;
fig. 4 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module is turned off, the negative switch module is turned off, and the first switch module is turned on according to the embodiment of the present invention;
fig. 5 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module is turned off, the negative switch module is turned off, and the first switch module is turned off according to the embodiment of the present invention;
fig. 6 is a schematic flowchart of a detection method of an insulation detection circuit according to another embodiment of the present invention;
fig. 7 is an equivalent circuit diagram of an insulation detection circuit corresponding to fig. 5;
fig. 8 is a schematic flowchart of a detection method of an insulation detection circuit according to another embodiment of the present invention;
fig. 9 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module is closed, the negative switch module is closed, and the first switch module is opened according to the embodiment of the present invention;
fig. 10 is a flowchart illustrating a detection method of an insulation detection circuit according to still another embodiment of the present invention.
Detailed Description
Features and exemplary embodiments of various aspects of the present invention will be described in detail below. In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of the present invention.
The embodiment of the invention provides an insulation detection circuit, a detection method and a battery management system, and by adopting the technical scheme in the embodiment of the invention, the insulation resistance value of a positive electrode high-voltage circuit at the side where a battery pack to be detected is located relative to a reference voltage end (namely, the insulation resistance value of a high voltage positive low-voltage ground) and the insulation resistance value of a negative electrode high-voltage circuit at the side where the battery pack to be detected is located relative to the reference voltage end (namely, the insulation resistance value of a high voltage negative low-voltage ground) can be detected separately, so that the independent alarm of the high voltage positive ground voltage low and the high voltage negative low-voltage ground is realized, and the.
It should be noted that the battery pack to be tested in the embodiment of the present invention may be a lithium ion battery, a lithium metal battery, a lead-acid battery, a nickel-metal-sealed battery, a nickel-metal hydride battery, a lithium sulfur battery, a lithium air battery, or a sodium ion battery, which is not limited herein. In terms of scale, the battery pack to be tested may also be a single battery cell, or may also be a battery module or a battery pack, which is not limited herein.
Fig. 1 is a schematic structural diagram of an insulation detection circuit according to an embodiment of the present invention. As shown in fig. 1, the insulation detection circuit includes: a first switch module K1, a first voltage division module F1, a second voltage division module F2, an isolation module C1, a third voltage division module F3, a signal generator Y1, and a processor P1.
The first switch module K1, the first voltage division module F1 and the second voltage division module F2 are arranged between the anode of the battery pack to be tested and the reference voltage end GND in series. The order of the first switch module K1, the first voltage division module F1 and the second voltage division module F2 is adjustable, and a first sampling point S1 is disposed between the first voltage division module F1 and the second voltage division module F2, and the first sampling point S1 is configured to provide a first sampling signal.
The isolation module C1, the third voltage division module F3 and the signal generator Y1 are arranged between the anode of the battery pack to be tested and the reference voltage end GND in series. A second sampling point S2 is disposed between the isolation module C1 and the third voltage dividing module F3, and the second sampling point S2 is configured to provide a second sampling signal; a third sampling point S3 is disposed between the third voltage dividing module F3 and the signal generator Y1, and the third sampling point S3 is configured to provide a third sampling signal.
The processor P1 is configured to calculate an insulation resistance value RP of the positive electrode high-voltage circuit on the side where the battery pack to be tested is located with respect to the reference voltage terminal GND and an insulation resistance value RN of the negative electrode high-voltage circuit on the side where the battery pack to be tested is located with respect to the reference voltage terminal GND according to the first sampling signal, the second sampling signal and the third sampling signal. Here, the processor P1 may be a processor P1 dedicated to the insulation detection circuit, or may be a processor P1 shared with other circuits.
Fig. 1 also shows CP, CN, Q1-Q6, Ru, Rv, and Rw, where CP and CN are equivalent capacitors between the positive electrode and the negative electrode of the battery pack to be tested and the casing thereof, Q1-Q6 are full-bridge power units capable of converting the dc voltage of the battery pack to be tested into a three-phase voltage required by a load (such as a motor), Ru, Rv, and Rw are equivalent insulation resistance values between a three-phase branch and the vehicle body of the entire vehicle, and Cx is an X capacitor.
Fig. 1 also shows an anode switch module K + and a cathode switch module K-, which can be understood as switch devices located between the battery pack to be tested and the load circuit, such as a relay and an Insulated Gate Bipolar Transistor IGBT (IGBT), and the on/off states of the anode switch module K + and the cathode switch module K-can be controlled by a processor P1 or other control devices, which is not limited herein.
Fig. 1 also shows a reference voltage terminal GND, and the actual voltages of the reference voltage terminal GND and the reference voltage terminal GND can be set according to the working scene and requirements of the insulation detection circuit, and in one example, the reference voltage terminal GND can be a shell of the battery pack.
Illustratively, the signal generator Y1 may be a Direct Digital Synthesizer (DDS) for generating an ac source signal with stable and adjustable frequency and smaller output voltage amplitude, and after injecting the ac source signal into the detection loop, collects an amplitude signal of the signal source voltage (collected from the second sampling point S2) and an amplitude signal between the isolation module C1 and the third voltage division module F3 (collected from the third sampling point S3).
In the embodiment of the invention, not only the isolation module C1, the third voltage division module F3 and the signal generator Y1 are arranged in series between the positive electrode of the battery pack to be tested of the insulation detection circuit and the reference voltage end GND, but also the first switch module K1, the first voltage division module F1 and the second voltage division module F2 are arranged in series. The first sampling point S1 is arranged between the first voltage division module F1 and the second voltage division module F2, the second sampling point S2 is arranged between the isolation module C1 and the third voltage division module F3, the third sampling point S3 is arranged between the third voltage division module F3 and the signal generator Y1, and the processor P1 can detect and obtain the insulation resistance value RP of the positive electrode high-voltage circuit on the side where the battery pack to be tested is relative to the reference voltage end GND and the insulation resistance value RN of the negative electrode high-voltage circuit on the side where the battery pack to be tested is located relative to the reference voltage end GND according to the first sampling signal provided by the first sampling point S1, the second sampling signal provided by the second sampling point S2 and the third sampling signal provided by the third sampling point S3, so that the independent alarm of high-voltage positive electrode high-voltage circuit and the low-voltage ground is realized, and the risk of false alarm is.
Different from the ac injection method in the prior art, because the insulation detection circuit in the embodiment of the present invention is additionally provided with the first switch module K1, the first voltage division module F1, and the second voltage division module F2, on the basis of obtaining the parallel resistance value RP// RN of the insulation resistance value RN of the positive electrode high-voltage circuit on the side where the battery pack to be tested is located with respect to the reference voltage end GND and the insulation resistance value RP of the negative electrode high-voltage circuit on the side where the battery pack to be tested is located with respect to the reference voltage end GND through detection, the insulation resistance value RP of the positive electrode high-voltage circuit on the side where the battery pack to be tested is located with respect to the reference voltage end GND and the insulation resistance value RN of the negative electrode high-voltage circuit on the side where the battery pack to be tested is located.
Fig. 2 is a schematic structural diagram of an insulation detection circuit according to another embodiment of the present invention, and as shown in fig. 2, the first switch module K1, the first voltage division module F1, the second voltage division module F2, the isolation module C1, and the third voltage division module F3 may be composed of components, and specific structures of the first switch module K1, the first voltage division module F1, the second voltage division module F2, the isolation module C1, and the third voltage division module F3 will be described below by way of example.
In one example, the first switching module K1 includes a first switching device, the first voltage divider module F1 includes a first resistor network R1, the second voltage divider module F2 includes a second resistor network R2, and the first sampling point S1 is located between the first resistor network R1 and the second resistor network R2.
The first switch device may be a relay, an IGBT, a Metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET), or the like, and an on-off state of the first switch device may be controlled by the processor P1 or other control devices, which is not limited herein.
The first resistor network R1 and the second resistor network R2 have a voltage division function, the positions of the first switch device and the first resistor network R1 and the second resistor network R2 are adjustable, and the variation range of the first sampling signal obtained from the first sampling point S1 can be adjusted by adjusting the resistance values of the first resistor network R1 and the second resistor network R2. In specific implementation, the first switch device can be controlled to be closed, the positive switch module K + can be controlled to be opened, and the negative switch module K-can be controlled to be opened, so that the first sampling signal can be obtained from the first sampling point S1.
In one example, the isolation module C1 includes a first capacitor, the third voltage division module F3 includes a third resistor network R3, the second sampling point S2 is located between the first capacitor and the third resistor network R3, and the third sampling point S3 is located between the third resistor network R3 and the signal generator Y1.
The third resistor network R3 has a voltage dividing function, and the variation range of the second sampling signal and the third sampling signal obtained from the second sampling point S2 can be adjusted by adjusting the resistance of the third resistor network R3. In specific implementation, the first switch device can be controlled to be opened, the positive switch module K + can be closed, and the negative switch module K-can be closed, so that the second sampling signal can be obtained from the second sampling point S2, and the third sampling signal can be obtained from the third sampling point S3.
In an example, as shown in fig. 2, the insulation detection circuit further includes a first voltage follower G1 and a second voltage follower G2. A first input end of the first voltage follower G1 is connected to the second sampling point S2, a second input end of the first voltage follower G1 is connected to an output end of the first voltage follower G1, and an output end of the first voltage follower G1 is further connected to the processor P1; the first input end of the second voltage follower G2 is connected to the third sampling point S3, the second input end of the second voltage follower G2 is connected to the output end of the second voltage follower G2, and the output end of the second voltage follower G2 is further connected to the processor P1.
The voltage follower that shows in fig. 2 comprises operational amplifier, because sine wave voltage is than higher, has surpassed processor P1's sampling range, consequently need carry out partial pressure with voltage signal and resample, and insulation resistance value is generally great, and directly adopts resistance partial pressure can lead to shunting for sampling is inaccurate, adopts the voltage follower can increase input impedance, improves the sampling precision, can also play the filtering simultaneously.
The insulation detection circuit shown in fig. 2 further includes a first filtering module, a second filtering module, and a third filtering module, which are used for filtering out high-frequency interference caused by high-frequency switching of an inverter during driving of the electric vehicle, and the high-frequency interference may cause relatively high-voltage fluctuation between the isolation capacitor and the sampling resistor, and exceed the range of the sampling unit.
The first end of the first filtering module is connected with the first sampling point S1, and the second end of the first filtering module is connected with the processor P1; the first end of the second filtering module is connected with the second sampling point S2, and the second end of the second filtering module is connected with the first input end of the first voltage follower G1; the first end of the third filtering module is connected to the third sampling point S3, and the second end of the third filtering module is connected to the first input end of the second voltage follower G2.
It should be noted that, a specific implementation form of the first filtering module, the second filtering module, and the third filtering module shown in fig. 2 is an RC filtering circuit, and it is understood that a person skilled in the art may also select a filtering circuit with another structure, which is not limited herein.
The following exemplifies a detection method of the insulation detection circuit in the embodiment of the present invention.
Fig. 3 is a schematic flow chart of a detection method of the insulation detection circuit according to an embodiment of the present invention. As shown in fig. 3, the detection method includes steps 301 to 303.
In step 301, the positive switch module K + is controlled to be opened, the negative switch module K-is controlled to be opened, and the first switch module K1 is controlled to be closed. Referring to fig. 4, fig. 4 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module K + is open, the negative switch module K-is open, and the first switch module K1 is closed according to the embodiment of the present invention, and at this time, the first sampling signal U1 is obtained from the first sampling point S1.
In step 302, the positive switch module K + is turned off, the negative switch module K-is turned off, and the first switch module K1 is turned off. Referring to fig. 5, fig. 5 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module K + is turned off, the negative switch module K-is turned off, and the first switch module K1 is turned off according to the embodiment of the present invention, at this time, the second sampling signal U2 is obtained from the second sampling point S2, and the third sampling signal U3 is obtained from the third sampling point S3.
In step 303, an insulation resistance value RP of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end GND and an insulation resistance value RN of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end GND are calculated according to the first sampling signal U1, the second sampling signal U2 and the third sampling signal U3.
Fig. 6 is a schematic flow chart of a detection method of an insulation detection circuit according to another embodiment of the present invention. Fig. 6 differs from fig. 3 in that step 303 in fig. 3 can be detailed as step 3031 and step 3032 in fig. 6.
In step 3031, a first parallel resistance value Rnp is obtained according to the second sampling signal U2 and the third sampling signal U3, where the first parallel resistance value Rnp is a parallel resistance value of an insulation resistance value of the positive electrode high-voltage circuit of the battery pack to be tested with respect to the reference voltage end GND and an insulation resistance value of the negative electrode high-voltage circuit of the battery pack to be tested with respect to the reference voltage end GND.
Referring to fig. 7, fig. 7 is an equivalent circuit diagram of the insulation detection circuit corresponding to fig. 5, Rnp is a resistance value of the positive insulation resistor RP and the negative insulation resistor RN connected in parallel, that is, Rnp is RN// RP, Cnp is a capacitance value of the positive capacitor CP and the negative capacitor CN connected in parallel, that is, Cnp is CN// CP, and the equivalent insulation resistance value Rnp is smaller than RN and RP, and those skilled in the art can refer to related technical data to obtain the first parallel resistance value Rnp according to the amplitudes and phase shifts of the second sampling signal U2 and the third sampling signal U3, which is not described herein again.
In step 3032, according to the first sampling signal U1 and the first parallel resistance value Rnp, the insulation resistance value RP of the positive electrode high-voltage circuit of the battery pack to be tested relative to the reference voltage end GND and the insulation resistance value RN of the negative electrode high-voltage circuit of the battery pack to be tested relative to the reference voltage end GND are obtained.
Specifically, in connection with the equivalent circuit structure in fig. 4, U1 and Rnp may be substituted into formula (1) -formula (3), where formula (1) -formula (3) are derived from kirchhoff's law:
wherein Ubat is the voltage at two ends of the battery pack, and the insulation resistance values of RP and RN can be calculated and obtained in a simultaneous mode (1), (2) and (3).
As described above, by adding the long hanging branch composed of the first resistor network R1, the second resistor network R2 and the first switch module K1, the problem of false insulation alarm of the whole vehicle due to inaccurate sampling of the insulation resistance caused by interference of the whole vehicle can be avoided. During specific implementation, if the measured insulation resistance value of the whole vehicle is too low, the measured insulation resistance value is merged into the first resistor network R1 and the second resistor network R2, then insulation sampling is carried out, and if the calculated insulation resistance value of the whole vehicle is larger than an alarm value, false detection is considered to be generated.
Fig. 8 is a schematic flowchart of a detection method of an insulation detection circuit according to another embodiment of the present invention. Fig. 8 differs from fig. 3 in that step 302 in fig. 3 can be subdivided into steps 3021 to 3024 in fig. 8.
In step 3021, the positive switch module K + is controlled to be closed, the negative switch module K-is controlled to be closed, and the first switch module K1 is controlled to be opened. Referring to fig. 9, fig. 9 is an equivalent circuit diagram of the insulation detection circuit when the positive switch module K + is closed, the negative switch module K-is closed, and the first switch module K1 is opened according to the embodiment of the present invention. At this time, the fourth sampling signal U4 is obtained from the second sampling point S2, and the fifth sampling signal U5 is obtained from the third sampling point S3.
In step 3022, a second parallel resistance value Rnpuwv is obtained according to the fourth sampling signal U4 and the fifth sampling signal U5, where the second parallel resistance value Rnpuwv is a parallel resistance value of the insulation resistance value RP of the positive high-voltage circuit on the side where the battery pack to be tested is located relative to the reference voltage end GND, the insulation resistance value RN of the negative high-voltage circuit on the side where the battery pack to be tested is located relative to the reference voltage end GND, and the insulation resistance values (Ru, Rw, and Rv) of the three-phase end of the entire vehicle. A person skilled in the art can refer to the related art data to obtain the second parallel resistance value Rnpuwv according to the amplitudes and phase shifts of the second sampling signal U2 and the third sampling signal U3, which is not described herein again.
In step 3023, it is determined whether the second parallel resistance value Rnpuwv is less than the first alarm threshold.
In step 3024, if the second parallel resistance Rnpuwv is smaller than the first alarm threshold, the positive switch module K + is controlled to be turned off, the negative switch module K-is controlled to be turned off, and the first switch module K1 is controlled to be turned off, that is, the motor controller is requested to be turned off, so that the equivalent circuit structure shown in fig. 5 is obtained, the second sampling signal U2 is obtained from the second sampling point S2, the third sampling signal U3 is obtained from the third sampling point S3, and Rnp is obtained through calculation.
Fig. 10 is a flowchart illustrating a detection method of an insulation detection circuit according to still another embodiment of the present invention. Fig. 10 is different from fig. 3 in that, after step 302 in fig. 3, the detection method further includes steps 304 to 307 in fig. 10.
In step 304, a first parallel resistance Rnp is obtained according to the second sampled signal U2 and the third sampled signal U3.
In step 305, a third parallel resistance value Ruwv, that is, a parallel resistance value of the insulation resistance values of the three-phase ends of the whole vehicle, is obtained according to the first parallel resistance value Rnp and the second parallel resistance value Rnpuwv.
In step 306, if the third parallel resistance value Ruwv is smaller than the second alarm threshold value, it is determined that the insulation resistance value of the three-phase end on the side where the load is located is faulty.
In step 307, if the third parallel resistance value Ruwv is greater than the second alarm threshold value, it is determined that the insulation resistance value of the side where the battery pack to be tested is located has a fault.
As described above, the technical scheme in the embodiment of the present invention is applicable to insulation resistance detection in a power vehicle, and can distinguish which section of the battery pack high-voltage system has a low insulation resistance value to ground, for example, comparing the parallel resistance value of the insulation resistance value of the entire vehicle three-phase end with the alarm threshold value of the insulation resistance value of the entire vehicle, it can be determined whether the insulation resistance value of the ac end of the entire vehicle is abnormal or the dc end is abnormal; when the insulation resistance value of the direct current end is abnormal, the insulation resistance value RP of the positive electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end GND and the insulation resistance value RN of the negative electrode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end GND are respectively compared with the corresponding alarm threshold values, so that whether the high-voltage positive insulation resistance value is abnormal or the high-voltage negative insulation resistance value is abnormal can be distinguished, and the condition that the insulation resistance value is mistakenly reported is avoided.
In addition, the embodiment of the invention can identify the failure of the single-end insulation resistance value, improve the stability of insulation detection, can identify the fault point more quickly by identifying the single-end RP or RN fault, improve the fault troubleshooting efficiency, quickly position the position of the insulation resistance value fault and improve the after-sale maintenance quality.
The embodiment of the invention also provides a battery management system, which comprises the insulation detection circuit, wherein the insulation detection circuit can be an independent circuit structure or a part of the whole circuit structure. For example, the insulation detection circuit in the embodiment of the present invention may be integrated in a battery management system of a battery pack, or may use a part of the entire circuit structure of the battery management system as insulation detection.
It should be clear that the embodiments in this specification are described in a progressive manner, and the same or similar parts in the embodiments are referred to each other, and each embodiment focuses on the differences from the other embodiments. For the device embodiments, reference may be made to the description of the method embodiments in the relevant part. Embodiments of the invention are not limited to the specific steps and structures described above and shown in the drawings. Those skilled in the art may make various changes, modifications and additions to, or change the order between the steps, after appreciating the spirit of the embodiments of the invention. Also, a detailed description of known process techniques is omitted herein for the sake of brevity.
The functional blocks shown in the above-described structural block diagrams may be implemented as hardware, software, firmware, or a combination thereof. When implemented in hardware, it may be, for example, an electronic circuit, an Application Specific Integrated Circuit (ASIC), suitable firmware, plug-in, function card, or the like. When implemented in software, the elements of an embodiment of the invention are the programs or code segments used to perform the required tasks. The program or code segments may be stored in a machine-readable medium or transmitted by a data signal carried in a carrier wave over a transmission medium or a communication link. A "machine-readable medium" may include any medium that can store or transfer information. Examples of a machine-readable medium include electronic circuits, semiconductor memory devices, ROM, flash memory, Erasable ROM (EROM), floppy disks, CD-ROMs, optical disks, hard disks, fiber optic media, Radio Frequency (RF) links, and so forth. The code segments may be downloaded via computer networks such as the internet, intranet, etc.
Embodiments of the present invention may be embodied in other specific forms without departing from its spirit or essential characteristics. For example, the algorithms described in the specific embodiments may be modified without departing from the basic spirit of the embodiments of the present invention. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the embodiments of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

Claims (10)

1. An insulation detection circuit, comprising: the device comprises a first switch module, a first voltage division module, a second voltage division module, an isolation module, a third voltage division module, a signal generator and a processor; wherein the content of the first and second substances,
the first switch module, the first voltage division module and the second voltage division module are arranged between the anode of the battery pack to be tested and a reference voltage end in series;
the isolation module, the third voltage division module and the signal generator are arranged between the anode of the battery pack to be tested and the reference voltage end in series;
a first sampling point is arranged between the first voltage division module and the second voltage division module, a second sampling point is arranged between the isolation module and the third voltage division module, and a third sampling point is arranged between the third voltage division module and the signal generator;
the first sampling point is configured to provide a first sampled signal, the second sampling point is configured to provide a second sampled signal, and the third sampling point is configured to provide a third sampled signal;
the processor is configured to calculate an insulation resistance value of a positive electrode high-voltage circuit of the battery pack to be tested relative to the reference voltage end and an insulation resistance value of a negative electrode high-voltage circuit of the battery pack to be tested relative to the reference voltage end according to the first sampling signal, the second sampling signal and the third sampling signal.
2. The insulation detection circuit of claim 1, wherein the first switching module comprises a first switching device, the first voltage divider module comprises a first resistive network, the second voltage divider module comprises a second resistive network, and the first sampling point is located between the first resistive network and the second resistive network.
3. The insulation detection circuit of claim 1, wherein the isolation module comprises a first capacitor, the third voltage division module comprises a third resistor network, the second sampling point is located between the first capacitor and the third resistor network, and the third sampling point is located between the third resistor network and the signal generator.
4. The insulation detection circuit according to claim 1, further comprising a first voltage follower and a second voltage follower; wherein the content of the first and second substances,
the first input end of the first voltage follower is connected with the second sampling point, the second input end of the first voltage follower is connected with the output end of the first voltage follower, and the output end of the first voltage follower is also connected with the processor;
and the first input end of the second voltage follower is connected with the third sampling point, the second input end of the second voltage follower is connected with the output end of the second voltage follower, and the output end of the second voltage follower is also connected with the processor.
5. The insulation detection circuit of claim 4, further comprising: the device comprises a first filtering module, a second filtering module and a third filtering module; wherein the content of the first and second substances,
the first end of the first filtering module is connected with the first sampling point, and the second end of the first filtering module is connected with the processor;
the first end of the second filtering module is connected with the second sampling point, and the second end of the second filtering module is connected with the first input end of the first voltage follower;
the first end of the third filtering module is connected with the third sampling point, and the second end of the third filtering module is connected with the first input end of the second voltage follower.
6. A battery management system comprising the insulation detection circuit according to any one of claims 1 to 5.
7. An insulation detection circuit detection method, for use in an insulation detection circuit as claimed in any one of claims 1 to 5, the method comprising:
controlling an anode switch module positioned between the anode of the battery pack to be tested and the load to be switched off, a cathode switch module positioned between the cathode of the battery pack to be tested and the load to be switched off and a first switch module to be switched on, and obtaining a first sampling signal from the first sampling point;
controlling the positive switch module to be switched off, the negative switch module to be switched off and the first switch module to be switched off, obtaining a second sampling signal from the second sampling point and obtaining a third sampling signal from the third sampling point;
and calculating the insulation resistance value of the anode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the cathode high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end according to the first sampling signal, the second sampling signal and the third sampling signal.
8. The method according to claim 7, wherein calculating the insulation resistance value of the positive high-voltage circuit on the side of the battery pack to be tested relative to the reference voltage terminal and the insulation resistance value of the negative high-voltage circuit on the side of the battery pack to be tested relative to the reference voltage terminal according to the first sampling signal, the second sampling signal and the third sampling signal comprises:
obtaining a first parallel resistance value according to the second sampling signal and the third sampling signal, wherein the first parallel resistance value is the parallel resistance value of the insulation resistance value of the positive high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end;
and obtaining the insulation resistance value of the positive high-voltage circuit at the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit at the side where the battery pack to be tested is located relative to the reference voltage end according to the first sampling signal and the first parallel resistance value.
9. The method of claim 7, wherein said controlling said positive switch module to be open, said negative switch module to be open, said first switch module to be open, obtaining a second sampled signal from said second sampling point, and obtaining a third sampled signal from said third sampling point comprises:
controlling the positive switch module to be closed, the negative switch module to be closed, the first switch module to be opened, obtaining a fourth sampling signal from the second sampling point, and obtaining a fifth sampling signal from the third sampling point;
obtaining a second parallel resistance value according to the fourth sampling signal and the fifth sampling signal, wherein the second parallel resistance value is the parallel resistance value of the insulation resistance value of the positive high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end, the insulation resistance value of the negative high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end, and the insulation resistance value of the whole vehicle three-phase end;
judging whether the second parallel resistance value is smaller than a first alarm threshold value;
and if the second parallel resistance value is smaller than the first alarm threshold value, the anode switch module is controlled to be switched off, the cathode switch module is controlled to be switched off, the first switch module is controlled to be switched off, a second sampling signal is obtained from the second sampling point, and a third sampling signal is obtained from the third sampling point.
10. The method of claim 7, wherein after obtaining the second sampled signal from the second sampled point and the third sampled signal from the third sampled point, the method further comprises:
obtaining a first parallel resistance value according to the second sampling signal and the third sampling signal, wherein the first parallel resistance value is the parallel resistance value of the insulation resistance value of the positive high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end and the insulation resistance value of the negative high-voltage circuit of the side where the battery pack to be tested is located relative to the reference voltage end;
obtaining a third parallel resistance value according to the first parallel resistance value and the second parallel resistance value, wherein the third parallel resistance value is the parallel resistance value of the insulation resistance value of the whole vehicle three-phase end;
if the third parallel resistance value is smaller than a second alarm threshold value, determining that the insulation resistance value of the three-phase end of the side where the load is located fails;
and if the third parallel resistance value is larger than the second alarm threshold value, determining that the insulation resistance value of the side where the battery pack to be tested is located fails.
CN201910156503.0A 2019-03-01 2019-03-01 Insulation detection circuit, insulation detection method and battery management system Pending CN110967560A (en)

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