WO2020177636A1 - 绝缘检测电路、方法以及电池管理系统 - Google Patents

绝缘检测电路、方法以及电池管理系统 Download PDF

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WO2020177636A1
WO2020177636A1 PCT/CN2020/077261 CN2020077261W WO2020177636A1 WO 2020177636 A1 WO2020177636 A1 WO 2020177636A1 CN 2020077261 W CN2020077261 W CN 2020077261W WO 2020177636 A1 WO2020177636 A1 WO 2020177636A1
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sampling
module
signal
circuit
frequency
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PCT/CN2020/077261
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English (en)
French (fr)
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但志敏
李盟
张伟
侯贻真
孙卫平
刘昌鑑
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宁德时代新能源科技股份有限公司
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
    • G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
    • G01R27/16—Measuring impedance of element or network through which a current is passing from another source, e.g. cable, power line
    • G01R27/18—Measuring resistance to earth, i.e. line to ground
    • 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]
    • G01R31/3644—Constructional arrangements

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  • This application relates to the field of new energy technologies, and in particular to an insulation detection circuit, method, and battery management system.
  • Electric vehicles instead of fuel vehicles have become a trend in the development of the automotive industry.
  • the power battery pack is one of the key components of electric vehicles, and the safety of its high-voltage power must be one of the primary considerations of the power battery system. Therefore, the inspection of the insulation performance of electric vehicles is an essential part.
  • the current method of detecting insulation resistance is low-frequency injection.
  • the low-frequency injection method requires a jumper isolation module between the high-voltage side and the low-voltage side, and a sampling module must be connected between the isolation module and the injected signal.
  • the insulation resistance of the vehicle can be calculated by parameters such as the amplitude of the injected signal, the frequency of the injected signal, the amplitude of the signal between the isolation module and the sampling module, and the capacitance of the capacitor module between the power battery to be tested and the power ground.
  • the capacitance value of the capacitor module between the power battery to be tested and the power ground is too large or the frequency of the injected signal is too high, the capacitive reactance of the capacitor module will be small.
  • the capacitive reactance of the capacitor module is too small, the accuracy of the insulation resistance value detection will be reduced.
  • the embodiments of the application provide an insulation detection circuit, an insulation detection method, and a battery management system, which can adjust the frequency of the injection signal based on the capacitance value of the capacitor module between the power battery to be tested and the power ground, and improve the capacitive reactance value of the capacitor module. Furthermore, the accuracy of the insulation resistance value detection is improved.
  • an insulation detection circuit including:
  • the first isolation module is respectively connected to the positive electrode of the power battery to be tested and one end of the sampling module;
  • Sampling module the other end of the sampling module is connected to one end of the signal generating module;
  • Signal generation module the other end of the signal generation module is connected to the power ground, used to provide injection signals to the power battery under test;
  • the processing module is used to determine the capacitance value of the capacitance module between the power battery to be tested and the power ground according to the first sampling signal collected from one end of the sampling module and the second sampling signal collected from one end of the signal generating module, and based on The capacitance value adjusts the frequency of the injected signal;
  • the processing module is also used to, after adjusting the frequency of the injected signal, obtain the to-be-injected signal according to the third sampling signal collected from one end of the sampling module, the fourth sampling signal collected from one end of the signal generation module, and the adjusted frequency of the injected signal. Measure the insulation resistance value of the power battery.
  • the processing module is specifically configured to reduce the frequency of the injected signal if the capacitance value is greater than the first preset threshold.
  • the processing module is specifically configured to increase the frequency of the injection signal if the capacitance value is less than the second preset threshold.
  • the processing module is specifically configured to obtain the first phase shift of the first sampling signal relative to the second sampling signal, and according to the first voltage amplitude of the first sampling signal and the second voltage amplitude of the second sampling signal Value, the first phase shift, and the frequency of the injected signal before adjustment to obtain the capacitance value.
  • the processing module is specifically configured to obtain the second phase shift of the third sampling signal relative to the fourth sampling signal, and according to the third voltage amplitude of the third sampling signal and the fourth voltage amplitude of the fourth sampling signal Value, the second phase shift, and the frequency of the injected signal after adjustment to obtain the insulation resistance value.
  • the circuit further includes:
  • the first end of the first sampling circuit is connected to one end of the sampling module, and the second end of the first sampling circuit is connected to the processing module.
  • the first sampling circuit is used to collect the first sampling signal from one end of the sampling module and The third sample signal.
  • the circuit further includes:
  • the first filter module is respectively connected to one end of the sampling module and the second isolation module;
  • the second isolation module is connected to the first sampling circuit, and the second isolation module is used to isolate the interference of the first sampling circuit on the first sampling signal and the third sampling signal.
  • the second isolation module includes:
  • the first input terminal of the first voltage follower is connected with the first filter module, and the output terminal of the first voltage follower is respectively connected with the second input terminal of the first voltage follower and the first sampling circuit.
  • the circuit further includes:
  • the second sampling circuit the first end of the second sampling circuit is connected to one end of the signal generation module, the second end of the second sampling circuit is connected to the processing module, and the second sampling circuit is used to collect the second sample from one end of the signal generation module Signal and the fourth sampled signal.
  • the circuit further includes:
  • the second filter module is respectively connected to one end of the signal generation module and the third isolation module;
  • the third isolation module is connected to the second sampling circuit, and the third isolation module is used to isolate the interference of the second sampling circuit on the second sampling signal and the fourth sampling signal.
  • the third isolation module includes:
  • a second voltage follower the first input terminal of the second voltage follower is connected with the second filter module, and the output terminal of the second voltage follower is respectively connected with the second input terminal of the second voltage follower and the second sampling circuit.
  • a battery management system including the insulation detection circuit as provided in the embodiments of the present application.
  • an insulation detection method is provided, which is applied to the insulation detection circuit provided in the embodiments of the present application, and the method includes:
  • the insulation resistance value of the power battery to be tested is obtained.
  • adjusting the frequency of the injected signal based on the capacitance value includes:
  • the frequency of the injected signal is reduced.
  • adjusting the frequency of the injected signal based on the capacitance value includes:
  • the frequency of the injected signal is increased.
  • the capacitance value of the capacitance module between the power battery to be tested and the power ground is determined, including :
  • the capacitance value is obtained according to the first voltage amplitude of the first sampling signal, the second voltage amplitude of the second sampling signal, the first phase shift, and the frequency of the injection signal before adjustment.
  • the frequency of the injected signal is adjusted to reduce the influence of the capacitive reactance value of the capacitor module on the detection of the insulation resistance value, thereby improving the detection of the insulation resistance value Accuracy.
  • FIG. 1 is a schematic structural diagram of an insulation detection circuit provided by the first embodiment of the application
  • FIG. 2 is a schematic structural diagram of an insulation detection circuit provided by a second embodiment of this application.
  • Figure 3 is an equivalent circuit diagram corresponding to Figure 2;
  • FIG. 4 is a schematic structural diagram of an insulation detection circuit provided by a third embodiment of the present application.
  • Fig. 5 is a schematic structural diagram of an insulation detection circuit provided by a fourth embodiment of the present application.
  • FIG. 6 is a schematic flowchart of an insulation detection method provided by some embodiments of the present application.
  • the power battery in the embodiments of the present application may be a lithium ion battery, a lithium metal battery, a lead-acid battery, a nickel barrier battery, a nickel hydrogen battery, a lithium sulfur battery, a lithium air battery, or a sodium ion battery.
  • the power battery can also be a single battery cell, or a battery module or a battery pack, which is not limited here.
  • the embodiment of the present application provides an insulation detection circuit and a detection method thereof. Based on the capacitance value of the capacitor module between the power battery to be tested and the power ground, the frequency of the injection signal is adjusted to increase the capacitance value of the capacitor module. When the capacitive reactance value of the capacitor module becomes larger, the influence of the capacitive reactance value of the capacitive module on the calculation of the insulation resistance value can be reduced to improve the accuracy of the insulation resistance value detection.
  • the insulation detection circuit includes:
  • the first isolation module G1 is respectively connected to the positive electrode of the power battery to be tested and one end of the sampling module H.
  • Sampling module H the other end of the sampling module H is connected to one end of the signal generating module S.
  • the signal generating module S the other end of the signal generating module S is connected to the power ground, and is used to provide an injection signal to the power battery under test.
  • the processing module P is used to determine the capacitance value of the capacitor module between the power battery to be tested and the power ground according to the first sampling signal collected from one end of the sampling module H and the second sampling signal collected from one end of the signal generating module S , And adjust the frequency of the injected signal based on the capacitance value.
  • the processing module P is also used to adjust the frequency of the injected signal according to the third sampling signal collected from one end of the sampling module H, the fourth sampling signal collected from one end of the signal generating module S, and the adjusted frequency of the injected signal, Obtain the insulation resistance value of the power battery to be tested.
  • Fig. 1 also shows the positive capacitance CP, the negative capacitance CN, the positive insulation resistance RP, and the negative insulation resistance RN of the power battery to be tested.
  • the positive capacitance CP is the equivalent capacitance of the positive electrode of the power battery under test relative to low-voltage ground
  • the negative capacitance CN is the equivalent capacitance of the negative power battery under test relative to low-voltage ground
  • the positive insulation resistance RP is the power battery under test.
  • the negative insulation resistance RN is the insulation resistance of the negative pole of the power battery under test relative to the low-voltage ground.
  • the capacitor module includes a positive capacitor CP and a negative capacitor CN.
  • Y capacitors are capacitors connected between the power line and the ground, and generally appear in pairs. Therefore, the positive capacitor CP and the negative capacitor CN can also be referred to as Y capacitors.
  • the first isolation module G1 includes an isolation capacitor C1.
  • the sampling module H includes a sampling resistor R1. Among them, one end of the isolation capacitor C1 is connected to the positive electrode of the power battery under test, and the other end of the isolation capacitor C1 is connected to one end of the sampling resistor R1. The other end of the sampling resistor R1 is connected to one end of the signal generating module S. The other end of the signal generating module S is connected to the power ground.
  • the isolation capacitor C1 can isolate the high-voltage and low-voltage sampling signals on the side of the power battery to be tested, avoiding the interference of high-voltage to low-voltage, and improving the stability of insulation detection.
  • the signal generation module S may be a direct digital synthesis (DDS) waveform generator.
  • DDS direct digital synthesis
  • the frequency stability and accuracy of the signal sent by the DDS waveform generator can reach the same level as the reference frequency, and fine frequency adjustment can be performed in a wide frequency range.
  • the signal source designed by this method can work in the modulation state, can adjust the output level, and can also output various waveforms, such as sine wave, triangle wave and square wave.
  • the DDS waveform generator When the insulation detection circuit is powered on, the DDS waveform generator generates a signal with frequency f 0 to the insulation detection circuit. Since the internal resistance of the power battery to be tested is very small, the DC power supply can be equivalent to a short circuit, that is, Figure 2 can be equivalent to Figure 3.
  • the equivalent insulation resistance value Rnp is smaller than RN and RP, so the insulation resistance value Rnp can be used as a measure of insulation performance.
  • ZCnp is the capacitive reactance of the Y capacitor, that is, the capacitive reactance corresponding to Cnp.
  • w1 is the angular frequency of the injection signal output by the signal generation module S
  • w1 2 ⁇ f 0
  • j is the symbol of the imaginary part.
  • ⁇ 1 is the first sampling signal collected by the processing module P from one end of the sampling resistor R1, which is relative to the second sampling signal collected by the processing module P from the end of the signal generating module S
  • u 1 is the first voltage amplitude of the first sampling signal collected from one end of the sampling resistor R1, that is, the voltage amplitude of the first sampling signal between the isolation capacitor C1 and the sampling resistor R1
  • U is the slave signal generating module
  • the second voltage amplitude of the second sampling signal collected at one end of S, the first sampling signal and the second sampling signal are signals of the same frequency.
  • the first phase shift of the first sampling signal relative to the second sampling signal can be calculated by using a known phase shift algorithm between signals of the same frequency, which will not be repeated here.
  • the processing module P calculates the capacitance value of the capacitance module according to the first voltage amplitude u1 of the first sampling signal, the second voltage amplitude U of the second sampling signal, the first phase shift ⁇ 1, and the frequency f 0 of the injection signal before adjustment. Among them, through the simultaneous formula (6) and formula (7), the calculation expression of the capacitance value of the capacitor module is as follows:
  • the insulation resistance value Rnp can be expressed by the following expression:
  • the amplitude ratio is the ratio between the voltage amplitude of the signal output by the signal generating module S and the voltage amplitude of the signal collected from one end of the sampling resistor R1.
  • the processing module P first calculates the capacitance value of the Y capacitor, and judges the magnitude of the capacitance value of the Y capacitor.
  • the processing module obtains the capacitance value of the Y capacitor, it is determined whether the capacitance value Cnp of the Y capacitor is greater than the preset capacitance threshold value Cnp1. If the capacitance value Cnp of the Y capacitor is greater than the preset capacitance threshold Cnp1, the frequency of the injected signal is reduced to increase the capacitance value of the Y capacitance, thereby reducing the influence of the capacitance value of the Y capacitance on the parallel impedance Z of Cnp and Rnp, In order to improve the detection accuracy of the insulation resistance value.
  • the processing module P can control the DDS waveform generator to reduce the frequency of the injection signal output by the DDS waveform generator.
  • the frequency of the injection signal output by the DDS waveform controller is f 1 , that is, f 1 ⁇ f 0 .
  • the processing module P acquisition fourth sampling signal of the third sampling signal and a signal between the sampling resistor R1 and capacitor C1 of the module isolation S output.
  • the processing module P obtains the second phase shift ⁇ 2 of the third sampling signal relative to the fourth sampling signal. Then, the insulation resistance value is calculated according to the third voltage amplitude u2 of the third sampling signal, the fourth voltage amplitude U of the fourth sampling signal, the second phase shift ⁇ 2, and the frequency f 1 of the adjusted injection signal. It is assumed here that the signal amplitude output by the signal generation module S does not change, so the fourth voltage amplitude of the fourth sampling signal is equal to the second voltage amplitude of the second sampling signal, that is, both are U.
  • the insulation resistance value can be calculated using the following expression:
  • w2 2 ⁇ f 1 .
  • the processing module P can directly calculate the insulation resistance value according to formula (9).
  • the processing module P may also determine whether the capacitance value Cnp of the Y capacitor is less than the preset capacitance threshold value Cnp2. If the capacitance value Cnp of the Y capacitor is less than the preset capacitance threshold value Cnp2, the frequency of the injected signal can be increased. Wherein, the preset capacitance threshold Cnp2 is less than the preset capacitance threshold Cnp1. By increasing the frequency of the injected signal to reduce the period of the injected signal, the update time of the insulation resistance can be shortened.
  • the processing module P controls the DDS waveform generator so that the frequency of the injection signal output by the DDS waveform controller is f 2 , where f 2 >f 0 .
  • the processing module P can be based on the voltage signal between the sampling resistor R1 and the isolation capacitor C1 and the voltage signal output by the signal generation module S and the frequency f 2 Calculating the insulation resistance value will not be repeated here.
  • the processing module P can directly calculate the insulation resistance value according to formula (9).
  • the processing module P may directly collect the first sampling signal or the third sampling signal from one end of the sampling resistor R1, and directly collect the second sampling signal or the fourth sampling signal from one end of the signal generating module S , It can also be collected by a dedicated sampling circuit.
  • the insulation detection circuit further includes a first sampling circuit D1 and a second sampling circuit D2.
  • the first end of the first sampling circuit D1 is connected to one end of the sampling resistor R1, and the second end of the first sampling circuit D1 is connected to the processing module P.
  • the first sampling circuit D1 is used to collect the voltage signal between the sampling resistor R1 and the isolation capacitor C1 from one end of the sampling resistor R1, such as the first sampling signal or the third sampling signal.
  • the first end of the second sampling circuit D2 is connected to one end of the signal generating module S, the second end of the second sampling circuit D2 is connected to the processing module P, and the second sampling circuit D2 is used to collect DDS signals from one end of the signal generating module S
  • the voltage signal generated by the generator such as the second sampling signal or the fourth sampling signal.
  • the processing module P may be a Microcontroller Unit (MCU), which is used to receive the first sampling signal from the first sampling circuit, receive the second sampling signal from the second sampling circuit, and obtain the first sampling signal relative to the second sampling circuit.
  • MCU Microcontroller Unit
  • the first phase shift of the sampled signal, and the capacitance value of the Y capacitor is obtained according to the first voltage amplitude of the first sampled signal, the second voltage amplitude of the second sampled signal, the first phase shift and the frequency of the injected signal before adjustment .
  • the processing module P may also receive the third sampling signal from the first sampling circuit, receive the fourth sampling signal from the second sampling circuit, obtain the second phase shift of the third sampling signal with respect to the fourth sampling signal, and then according to the third sampling signal The third voltage amplitude of the fourth sampling signal, the second phase shift, and the frequency of the injected signal after adjustment to obtain the insulation resistance value.
  • the insulation detection circuit further includes: a first filter module B1, a second isolation module G2, a second filter module B2, and a third isolation module G3.
  • the first filter module B1 is respectively connected to one end of the sampling module H and the second isolation module G2.
  • the second isolation module G2 is connected to the first sampling circuit D1.
  • the second isolation module G2 is used to isolate the interference of the first sampling circuit D1 to the signal between the first isolation module G1 and the sampling module H.
  • the first filter module B1 filters the signal between the first isolation module G1 and the sampling module H, can suppress noise and prevent interference, and improve the sampling accuracy of the signal between the first isolation module G1 and the sampling module H , Thereby improving the detection accuracy of the insulation resistance value.
  • the second filter module B2 is respectively connected to one end of the signal generating module S and the third isolation module G3.
  • the third isolation module G3 is connected to the second sampling circuit D2, and the third isolation module G3 is used to isolate the interference of the second sampling circuit D2 to the signal sent by the DDS waveform generator.
  • the second filter module B2 filters the signal sent by the DDS waveform generator, can suppress noise and prevent interference, improve the sampling accuracy of the signal sent by the DDS waveform generator, and thereby improve the detection accuracy of the insulation resistance value.
  • FIG. 5 shows a schematic structural diagram of a capacitance calibration circuit in still other embodiments of the present application.
  • Fig. 5 shows specific structures of the first filter module B1, the second isolation module G2, the second filter module B2, and the third isolation module G3.
  • the first filter module B1 includes a resistor R2 and a capacitor C2.
  • the second isolation module G2 includes a first voltage follower A1.
  • one end of the resistor R2 is connected to one end of the sampling resistor R1, and the other end of the resistor R2 is respectively connected to one end of the capacitor C2 and the first input end of the first voltage follower A1.
  • the other end of the capacitor C2 is connected to the power ground.
  • the second input terminal of the first voltage follower A1 is connected to the output terminal of the first voltage follower A1, and the output terminal of the first voltage follower A1 is connected to the first sampling circuit D1.
  • the second filter module B2 includes a resistor R3 and a capacitor C3.
  • the third isolation module G3 includes a second voltage follower A2.
  • one end of the resistor R3 is connected to the DDS waveform generator, and the other end of the resistor R3 is respectively connected to one end of the capacitor C3 and the first input end of the second voltage follower A2.
  • the other end of the capacitor C3 is connected to the power ground.
  • the second input terminal of the second voltage follower A2 is connected to the output terminal of the second voltage follower A2, and the output terminal of the second voltage follower A2 is connected to the second sampling circuit D2.
  • both the first sampling circuit D1 and the second sampling circuit D2 may include a resistor divider and an MCU. Because the sine wave voltage output by the DDS waveform generator is relatively high, it exceeds the sampling range of the MCU in the first sampling circuit and the MCU in the second sampling circuit. Therefore, it is necessary to divide the voltage signal between the sampling resistor R1 and the isolation capacitor C1 through a resistor divider before sampling. Since the insulation resistance value is generally relatively large, the direct use of resistor divider will cause shunting, making the sampling of the voltage signal between the sampling resistor R1 and the isolation capacitor C1 inaccurate, so adding a voltage follower can increase the input impedance and prevent the first sampling The influence of circuit D1 on the sampled signal. In addition, the voltage follower can also play a role in further filtering.
  • the function of the second voltage follower A2 is similar to that of the first voltage follower A1, and will not be repeated here.
  • An embodiment of the present application also provides a battery management system, which includes the above insulation detection circuit.
  • FIG. 6 is a schematic flowchart of an insulation detection method provided by some embodiments of the application, which is used in the insulation detection circuit shown in FIGS. 1 to 5.
  • the insulation detection method provided by the embodiment of the application includes the following steps:
  • S610 Determine the capacitance value of the capacitor module between the power battery to be tested and the power ground according to the first sampling signal collected from one end of the sampling module H and the second sampling signal collected from one end of the signal generating module S.
  • step S610 first obtain the first phase shift of the first sampling signal relative to the second sampling signal. Then, the capacitance value is obtained according to the first voltage amplitude of the first sampling signal, the second voltage amplitude of the second sampling signal, the first phase shift, and the frequency of the injected signal before adjustment.
  • the specific calculation method of the capacitance value of the capacitor module can refer to formula (1) to formula (8), which will not be repeated here.
  • step S620 if the capacitance value is greater than the first preset threshold, the frequency of the injected signal is reduced to increase the capacitive reactance value of the capacitance module, thereby improving the accuracy of insulation detection.
  • the frequency of the injected signal is increased to increase the detection speed of the insulation resistance value.
  • step S630 first obtain the second phase shift of the third sampling signal relative to the fourth sampling signal. Then, the insulation resistance value is obtained according to the third voltage amplitude of the third sampling signal, the fourth voltage amplitude of the fourth sampling signal, the second phase shift, and the frequency of the adjusted injection signal.
  • the specific calculation method of the insulation resistance value can refer to formula (9) and formula (10), which will not be repeated here.
  • the frequency of the injected signal is reduced to increase the capacitance value of the capacitance module, thereby reducing the capacitance value of the capacitance module to the parallel impedance of Cnp and Rnp Z influence to improve the accuracy of insulation detection.
  • the frequency of the injected signal can be increased to reduce the update time of the insulation resistance value.
  • the frequency of the injected signal can be adjusted according to different application scenarios, that is, the frequency of the injected signal can be determined for different vehicle models and for different vehicle Y capacitors, thereby ensuring the insulation resistance Value accuracy eliminates the problem of low insulation resistance caused by the entire vehicle Y capacitor.
  • the insulation detection circuit and detection method provided in the embodiments of the present application also improve the safety performance of the entire vehicle. At the same time, by adjusting the frequency of the injected signal, the stability of the entire vehicle can be improved, and the insulation error caused by the accuracy of the insulation resistance measurement can be eliminated. Report and other issues.

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Abstract

一种绝缘检测电路、方法以及电池管理系统。该电路包括：第一隔离模块(G1)，与待测动力电池的正极和采样模块(H)的一端连接；采样模块(H)，其另一端与信号发生模块(S)的一端连接；信号发生模块(S)，其另一端与电源地连接，用于向待测动力电池提供注入信号；处理模块(P)，用于根据从采样模块(H)的一端采集的第一采样信号和从信号发生模块(S)的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值，并基于电容值调整注入信号的频率；处理模块(P)还用于根据从采样模块(H)的一端采集的第三采样信号、从信号发生模块(S)的一端采集的第四采样信号以及调整后的注入信号的频率，得出待测动力电池的绝缘电阻值。提高了绝缘检测的精度。

Description

绝缘检测电路、方法以及电池管理系统
相关申请的交叉引用
本申请要求享有于2019年03月01日提交的名称为“绝缘检测电路、方法以及电池管理系统”的中国专利申请201910155777.8的优先权，该申请的全部内容通过引用并入本文中。
技术领域
本申请涉及新能源技术领域，特别是涉及一种绝缘检测电路、方法以及电池管理系统。
背景技术
电动汽车替代燃油汽车已成为汽车业发展的趋势，电池包的续行里程、使用寿命及使用安全等对电动汽车的使用都显得尤为重要。动力电池包作为电动汽车的关键部件之一，其高压电的安全性必须放在动力电池系统的首要考虑对象之一。因此，对电动汽车绝缘性能的检测是必不可少的一部分。
目前检测绝缘电阻的方法有低频注入法。低频注入法需要在高压侧与低压侧之间跨接隔离模块，隔离模块与注入信号之间需要连接采样模块。通过注入信号的幅值、注入信号的频率、隔离模块和采样模块之间信号的幅值以及待测动力电池和电源地之间的电容模块的电容值等参数可以计算整车的绝缘电阻。
但是，若待测动力电池和电源地之间的电容模块的电容值过大或注入信号的频率过高，均会导致电容模块的容抗较小。而当电容模块的容抗过小时，会降低绝缘电阻值检测的精准性。
发明内容
本申请实施例提供一种绝缘检测电路、绝缘检测方法以及电池管理系统，能够基于待测动力电池和电源地之间的电容模块的电容值调整注入信号的频率，提高电容模块的容抗值，进而提高绝缘电阻值检测的精确性。
根据本申请实施例的一方面，提供一种绝缘检测电路，该电路包括：
第一隔离模块，分别与待测动力电池的正极和采样模块的一端连接；
采样模块，采样模块的另一端与信号发生模块的一端连接；
信号发生模块，信号发生模块的另一端与电源地连接，用于向待测动力电池提供注入信号；
处理模块，用于根据从采样模块的一端采集的第一采样信号和从信号发生模块的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值，并基于电容值调整注入信号的频率；
处理模块还用于在调整注入信号的频率之后，根据从采样模块的一端采集的第三采样信号、从信号发生模块的一端采集的第四采样信号以及调整后的注入信号的频率，得出待测动力电池的绝缘电阻值。
在一个实施例中，处理模块具体用于若电容值大于第一预设阈值，则减小注入信号的频率。
在一个实施例中，处理模块具体用于若电容值小于第二预设阈值，则增大注入信号的频率。
在一个实施例中，处理模块具体用于获取第一采样信号相对于第二采样信号的第一相移，并根据第一采样信号的第一电压幅值、第二采样信号的第二电压幅值、第一相移以及调整前注入信号的频率，得到电容值。
在一个实施例中，处理模块具体用于获取第三采样信号相对于第四采样信号的第二相移，并根据第三采样信号的第三电压幅值、第四采样信号的第四电压幅值、第二相移以及调整后注入信号的频率，得到绝缘电阻值。
在一个实施例中，电路还包括：
第一采样电路，第一采样电路的第一端与采样模块的一端连接，第一采样电路的第二端与处理模块连接，第一采样电路用于从采样模块的一端采集第一采样信号和第三采样信号。
在一个实施例中，电路还包括：
第一滤波模块，分别与采样模块的一端和第二隔离模块连接；
第二隔离模块，与第一采样电路连接，第二隔离模块用于隔离第一采样电路对第一采样信号和第三采样信号的干扰。
在一个实施例中，第二隔离模块包括：
第一电压跟随器，第一电压跟随器的第一输入端与第一滤波模块连接，第一电压跟随器的输出端分别与第一电压跟随器的第二输入端和第一采样电路连接。
在一个实施例中，电路还包括：
第二采样电路，第二采样电路的第一端与信号发生模块的一端连接，第二采样电路的第二端与处理模块连接，第二采样电路用于从信号发生模块的一端采集第二采样信号和第四采样信号。
在一个实施例中，电路还包括：
第二滤波模块，分别与信号发生模块的一端和第三隔离模块连接；
第三隔离模块，与第二采样电路连接，第三隔离模块用于隔离第二采样电路对第二采样信号和第四采样信号的干扰。
在一个实施例中，第三隔离模块包括：
第二电压跟随器，第二电压跟随器的第一输入端与第二滤波模块连接，第二电压跟随器的输出端分别与第二电压跟随器的第二输入端和第二采样电路连接。
根据本申请实施例的另一方面，提供一种电池管理系统，包括如本申请实施例提供的绝缘检测电路。
根据本申请实施例的再一方面，提供一种绝缘检测方法，应用于如本申请实施例提供的绝缘检测电路，方法包括：
根据从采样模块的一端采集的第一采样信号和从信号发生模块的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值；
基于电容值调整注入信号的频率；
根据从采样模块的一端采集的第三采样信号、从信号发生模块的一端采集的第四采样信号以及调整后的注入信号的频率，得出待测动力电池的绝缘电阻值。
在一个实施例中，基于电容值调整注入信号的频率，包括：
若电容值大于第一预设阈值，则减小注入信号的频率。
在一个实施例中，基于电容值调整注入信号的频率，包括：
若电容值小于第二预设阈值，则增大注入信号的频率。
在一个实施例中，根据从采样模块的一端采集的第一采样信号和从信号发生模块的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值，包括：
获取第一采样信号相对于第二采样信号的第一相移；
根据第一采样信号的第一电压幅值、第二采样信号的第二电压幅值、第一相移以及调整前注入信号的频率，得到电容值。
根据本申请实施例，基于待测动力电池和电源地之间的电容模块的电容值，调整注入信号的频率以降低电容模块的容抗值对绝缘电阻值检测的影响，从而提高绝缘电阻值检测的精度。
附图说明
下面将通过参考附图来描述本申请示例性实施例的特征、优点和技术效果。
图1为本申请第一实施例提供的绝缘检测电路的结构示意图；
图2为本申请第二实施例提供的绝缘检测电路的结构示意图；
图3为与图2对应的等效电路图；
图4本申请第三实施例提供的绝缘检测电路的结构示意图；
图5本申请第四实施例提供的绝缘检测电路的结构示意图；
图6本申请一些实施例提供的绝缘检测方法的流程示意图。
具体实施方式
下面结合附图和实施例对本申请的实施方式作进一步详细描述。以下 实施例的详细描述和附图用于示例性地说明本申请的原理，但不能用来限制本申请的范围，即本申请不限于所描述的实施例。
需要说明的是，在本文中，诸如第一和第二等之类的关系术语仅仅用来将一个实体或者操作与另一个实体或操作区分开来，而不一定要求或者暗示这些实体或操作之间存在任何这种实际的关系或者顺序。而且，术语“包括”、“包含”或者其任何其他变体意在涵盖非排他性的包含，从而使得包括一系列要素的过程、方法、物品或者设备不仅包括那些要素，而且还包括没有明确列出的其他要素，或者是还包括为这种过程、方法、物品或者设备所固有的要素。在没有更多限制的情况下，由语句“包括……”限定的要素，并不排除在包括要素的过程、方法、物品或者设备中还存在另外的相同要素。
需要说明的是，本申请实施例中的动力电池可以为锂离子电池、锂金属电池、铅酸电池、镍隔电池、镍氢电池、锂硫电池、锂空气电池或者钠离子电池，在此不做限定。从规模而言，动力电池也可以为电芯单体，也可以是电池模组或电池包，在此不做限定。
本申请实施例提供一种绝缘检测电路及其检测方法，基于待测动力电池和电源地之间的电容模块的电容值，调整注入信号的频率以增大电容模块的容抗值。当电容模块的容抗值变大时，可以降低电容模块的容抗值对绝缘阻值计算的影响，以提高绝缘电阻值检测的精度。
下面首先结合附图对本申请实施例提供的绝缘检测电路进行详细说明。如图1所示，绝缘检测电路包括：
第一隔离模块G1，分别与待测动力电池的正极和采样模块H的一端连接。
采样模块H，采样模块H的另一端与信号发生模块S的一端连接。
信号发生模块S，信号发生模块S的另一端与电源地连接，用于向待测动力电池提供注入信号。
处理模块P，用于根据从采样模块H的一端采集的第一采样信号和从信号发生模块S的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值，并基于电容值调整注入信号的频率。
处理模块P还用于在调整注入信号的频率之后，根据从采样模块H的一端采集的第三采样信号、从信号发生模块S的一端采集的第四采样信号以及调整后的注入信号的频率，得出待测动力电池的绝缘电阻值。
图1中还示出了待测动力电池的正极电容CP、负极电容CN、正极绝缘电阻RP和负极绝缘电阻RN。
可以理解地是，正极电容CP为待测动力电池正极相对于低压地的等效电容，负极电容CN为待测动力电池负极相对于低压地的等效电容，正极绝缘电阻RP为待测动力电池正极相对于低压地(即电源地)的绝缘电阻，负极绝缘电阻RN为待测动力电池负极相对于低压地的绝缘电阻。
其中，电容模块包括正极电容CP和负极电容CN。Y电容是分别跨接在电力线和地之间的电容，一般成对出现。因此，正极电容CP和负极电容CN也可以称为Y电容。
参见图2，在一些示例中，第一隔离模块G1包括隔离电容C1。采样模块H包括采样电阻R1。其中，隔离电容C1的一端与待测动力电池的正极连接，隔离电容C1的另一端与采样电阻R1的一端连接。采样电阻R1的另一端与信号发生模块S的一端连接。信号发生模块S的另一端与电源地连接。
在该实施例中，隔离电容C1能够将待测动力电池侧的高压和低压采样信号隔离开来，避免了高压对低压的干扰，提高了绝缘检测的稳定性。
在一些实施例中，信号发生模块S可以为直接数字频率合成(Direct Digital Synthesis，DDS)波形发生器。DDS波形发生器发出的信号的频率稳定度和准确度能够达到与基准频率相同的水平，并且可以在很宽的频率范围内进行精细的频率调节。采用这种方法设计的信号源可工作于调制状态，可以对输出电平进行调节，也可以输出各种波形，比如，正弦波、三角波和方波等波形。
当绝缘检测电路上电后，DDS波形发生器产生频率为f 0的信号至绝缘检测电路。由于待测动力电池的内阻很小，因此可以将直流电源等效成短路，即可以将图2等效成图3。图3中，Rnp为正极绝缘电阻RP和负极绝缘电阻RN并联后的阻值，即Rnp＝RP//RN，Cnp为正极电容CP和负极 电容CN并联后的容值，即Cnp＝CN//CP，等效后的绝缘阻值Rnp相对于RN和RP而言更小，因此可以将绝缘电阻值Rnp作为衡量绝缘性能的标准。
为了降低电容模块的电容值过大对绝缘阻值检测的影响，在进行绝缘电阻值的计算之前，需要先计算电容模块的电容值，并判断电容模块的电容值对绝缘电阻值的检测是否有影响。
下面结合图3对本申请实施例中电容模块的电容值的计算过程进行介绍。
假设Cnp和Rnp的等效阻抗为Z，根据串并联公式可以得到Z的表达式：
Figure PCTCN2020077261-appb-000001
其中，ZCnp为Y电容的容抗，即Cnp对应的容抗。若基于基尔霍夫定律，以及电阻和电容的并联公式，可得出Z的向量形式：
Figure PCTCN2020077261-appb-000002
其中，w1为信号发生模块S输出的注入信号的角频率，w1＝2πf 0，j为虚部符号。
假设Z1为Cnp、Rnp以及隔离电容C1的等效阻抗，θ1为处理模块P从采样电阻R1的一端采集的第一采样信号，相对于处理模块P从信号发生模块S一端采集的第二采样信号的第一相移，则基于基尔霍夫定律可得出如下表达式：
Figure PCTCN2020077261-appb-000003
其中，u 1为从采样电阻R1的一端采集的第一采样信号的第一电压幅值，即隔离电容C1与采样电阻R1之间的第一采样信号的电压幅值，U为从信号发生模块S的一端采集的第二采样信号的第二电压幅值，第一采样信号和第二采样信号是同频率的信号。其中，第一采样信号相对于第二采样信号的第一相移可以利用已知的同频信号之间的相移算法进行计算，在此不再赘述。
其中，Z1与Z之间的关系可以利用如下的表达式进行表示：
Figure PCTCN2020077261-appb-000004
由公式(3)和公式(4)联立，可以利用下面的表达式表示Z：
Figure PCTCN2020077261-appb-000005
联合公式(2)和公式(5)，由实部等于实部可以得出以下等式：
Figure PCTCN2020077261-appb-000006
联合公式(2)和公式(5)，由虚部等于虚部可以得出以下等式：
Figure PCTCN2020077261-appb-000007
处理模块P根据第一采样信号的第一电压幅值u1、第二采样信号的第二电压幅值U、第一相移θ1以及调整前注入信号的频率f 0，计算电容模块的电容值。其中，通过联立公式(6)和公式(7)，电容模块的电容值的计算表达式如下：
Figure PCTCN2020077261-appb-000008
在本申请的实施例中，若不考虑隔离电容C1的电容值对绝缘检测精确度的影响，联立公式(2)和公式(5)，将Cnp作为已知量，即可计算得出Rnp。其中，绝缘电阻值Rnp可以利用下面的表达式进行表示：
Figure PCTCN2020077261-appb-000009
但是，若Y电容的电容值Cnp过大，则Y电容的容抗较小，即会导致Cnp和Rnp的并联阻抗Z较小。在此种情况下，即使Rnp增大，Cnp和Rnp的并联阻抗Z主要还是受Cnp的影响，Z的取值仍然较小。
也就是说，若Y电容的容抗值较小，Cnp和Rnp的并联阻抗Z受Rnp的影响很小，这将会导致一个较宽的绝缘电阻值范围只对应一个较窄范围 的幅值比。其中，幅值比为信号发生模块S输出的信号的电压幅值与从采样电阻R1的一端采集的信号的电压幅值之间的比值。
根据公式(2)和公式(5)可以得知，绝缘电阻值Rnp的计算与信号发生模块S输出的信号的电压幅值以及从采样电阻R1和隔离电容C1之间采集的信号的电压幅值有关。对于一个固定的绝缘电阻值范围，若该绝缘电阻值范围对应的幅值比范围越大，则绝缘电阻值Rnp的检测精度越高。
因此，若Y电容的电容值过大，则会降低Y电容的容抗，从而降低绝缘检测的精度。为了提高绝缘电阻值的检测精度，处理模块P先计算Y电容的电容值，并对Y电容的电容值的大小进行判断。
作为一个示例，当处理模块获取Y电容的电容值之后，判断Y电容的电容值Cnp是否大于预设电容阈值Cnp1。如果Y电容的电容值Cnp大于预设电容阈值Cnp1，则降低注入信号的频率，以增大Y电容的容抗值，从而降低Y电容的容抗值对Cnp和Rnp的并联阻抗Z的影响，以提高绝缘电阻值的检测精度。
处理模块P可以控制DDS波形发生器，以使DDS波形发生器输出的注入信号的频率降低。例如，DDS波形控制器输出的注入信号的频率为f 1，即f 1<f 0。当DDS波形发生器输出的信号频率降低为f 1之后，处理模块P采集采样电阻R1和隔离电容C1之间的第三采样信号以及信号发生模块S输出的第四采样信号。
处理模块P获取第三采样信号相对于第四采样信号的第二相移θ2。然后根据第三采样信号的第三电压幅值u2、第四采样信号的第四电压幅值U、第二相移θ2以及调整后注入信号的频率f 1，计算绝缘电阻值。此处假设信号发生模块S输出的信号幅值不发生变化，因此第四采样信号的第四电压幅值与第二采样信号的第二电压幅值相等，即均为U。绝缘电阻值可以利用下面的表达式进行计算：
Figure PCTCN2020077261-appb-000010
其中，w2＝2πf 1。通过降低注入信号的频率以增大Y电容的容抗，从而提高绝缘电阻值的检测精度。
若Y电容的电容值Cnp小于等于预设阈值Cnp1，则代表Y电容的电容值Cnp对绝缘电阻值的检测影响不大。则处理模块P可以直接根据公式(9)计算绝缘电阻值。
在本申请的另一些实施例中，为了降低绝缘阻值的更新时间，即提高绝缘阻值的更新速度，处理模块P还可以判断Y电容的电容值Cnp是否小于预设电容阈值Cnp2。若Y电容的电容值Cnp小于预设电容阈值Cnp2，则可以增加注入信号的频率。其中，预设电容阈值Cnp2小于预设电容阈值Cnp1。通过增加注入信号的频率以降低注入信号的周期，从而可以缩短绝缘阻值的更新时间。
作为一个示例，若Y电容的电容值Cnp小于预设电容阈值Cnp2，则处理模块P控制DDS波形发生器，以使DDS波形控制器输出的注入信号的频率为f 2，其中f 2>f 0。类似地，当DDS波形发生器输出的信号频率增加为f 2之后，处理模块P根据采样电阻R1和隔离电容C1之间的电压信号以及信号发生模块S输出的电压信号以及频率f 2，即可以计算绝缘电阻值，在此不再赘述。
若Y电容的电容值Cnp大于等于预设电容阈值Cnp2且小于等于预设电容阈值Cnp1，则处理模块P可以直接根据公式(9)计算绝缘电阻值。
在本申请的一些实施例中，处理模块P可以直接从采样电阻R1的一端采集第一采样信号或第三采样信号，以及直接从信号发生模块S的一端采集第二采样信号或第四采样信号，也可以通过专用的采样电路采集。
参见图4，绝缘检测电路还包括第一采样电路D1和第二采样电路D2。
在一些实施例中，第一采样电路D1的第一端与采样电阻R1的一端连接，第一采样电路D1的第二端与处理模块P连接。第一采样电路D1用于从采样电阻R1的一端采集采样电阻R1和隔离电容C1之间的电压信号，例如第一采样信号或第三采样信号。
第二采样电路D2的第一端与信号发生模块S的一端连接，第二采样电路D2的第二端与处理模块P连接，第二采样电路D2用于从信号发生模 块S的一端采集DDS信号发生器产生的电压信号，例如第二采样信号或第四采样信号。
其中，处理模块P可以为微控制单元(Microcontroller Unit，MCU)，用于从第一采样电路接收第一采样信号，从第二采样电路接收第二采样信号，获取第一采样信号相对于第二采样信号的第一相移，并根据第一采样信号的第一电压幅值、第二采样信号的第二电压幅值、第一相移以及调整前注入信号的频率，得到Y电容的电容值。
处理模块P还可以从第一采样电路接收第三采样信号，从第二采样电路接收第四采样信号，获取第三采样信号相对于第四采样信号的第二相移，并根据第三采样信号的第三电压幅值、第四采样信号的第四电压幅值、第二相移以及调整后注入信号的频率，得到绝缘电阻值。
参见图4，在本申请的一些实施例中，绝缘检测电路还包括：第一滤波模块B1、第二隔离模块G2、第二滤波模块B2和第三隔离模块G3。
其中，第一滤波模块B1分别与采样模块H的一端和第二隔离模块G2连接。第二隔离模块G2，与第一采样电路D1连接。第二隔离模块G2用于隔离第一采样电路D1对第一隔离模块G1和采样模块H之间信号的干扰。
其中，第一滤波模块B1对第一隔离模块G1和采样模块H之间的信号进行滤波，能够抑制噪声和防止干扰，提高了对第一隔离模块G1和采样模块H之间的信号的采样精度，进而提高绝缘电阻值的检测精度。
其中，第二滤波模块B2分别与信号发生模块S的一端和第三隔离模块G3连接。第三隔离模块G3，与第二采样电路D2连接，第三隔离模块G3用于隔离第二采样电路D2对DDS波形发生器发出的信号的干扰。
其中，第二滤波模块B2对DDS波形发生器发出的信号进行滤波，能够抑制噪声和防止干扰，提高了对DDS波形发生器发出的信号的采样精度，进而提高绝缘电阻值的检测精度。
图5示出本申请再一些实施例中电容校准电路的结构示意图。图5示出第一滤波模块B1、第二隔离模块G2、第二滤波模块B2和第三隔离模块G3的具体结构。
参见图5，在一些示例中，第一滤波模块B1包括电阻R2和电容C2。第二隔离模块G2包括第一电压跟随器A1。
其中，电阻R2的一端与采样电阻R1的一端连接，电阻R2的另一端分别与电容C2的一端和第一电压跟随器A1的第一输入端连接。电容C2的另一端与电源地连接。
第一电压跟随器A1的第二输入端与第一电压跟随器A1的输出端连接，第一电压跟随器A1的输出端与第一采样电路D1连接。
参见图5，在一些示例中，第二滤波模块B2包括电阻R3和电容C3。第三隔离模块G3包括第二电压跟随器A2。
其中，电阻R3的一端与DDS波形发生器连接，电阻R3的另一端分别与电容C3的一端和第二电压跟随器A2的第一输入端连接。电容C3的另一端与电源地连接。
第二电压跟随器A2的第二输入端与第二电压跟随器A2的输出端连接，第二电压跟随器A2的输出端与第二采样电路D2连接。
其中，第一采样电路D1和第二采样电路D2均可以包括电阻分压器和MCU。由于DDS波形发生器输出的正弦波电压比较高，超过了第一采样电路中MCU和第二采样电路中MCU的采样范围。因此需要将采样电阻R1与隔离电容C1之间的电压信号通过电阻分压器分压后再进行采样。由于绝缘电阻值一般比较大，直接采用电阻分压会导致分流，使得对采样电阻R1与隔离电容C1之间的电压信号采样不准，因此加入电压跟随器可以增大输入阻抗，防止第一采样电路D1对采样信号的影响。并且，电压跟随器还可以起到进一步滤波的作用。
第二电压跟随器A2的作用与第一电压跟随器A1相类似，在此不再赘述。
本申请实施例还提供一种电池管理系统，该电池管理系统包括如上的绝缘检测电路。
图6为本申请一些实施例提供的绝缘检测方法的流程示意图，用于如图1-图5的绝缘检测电路。本申请实施例提供的绝缘检测方法包括以下步骤：
S610，根据从采样模块H的一端采集的第一采样信号和从信号发生模块S的一端采集的第二采样信号，确定待测动力电池和电源地之间的电容模块的电容值。
S620，基于电容值调整注入信号的频率。
S630，根据从采样模块H的一端采集的第三采样信号、从信号发生模块S的一端采集的第四采样信号以及调整后的注入信号的频率，得出待测动力电池的绝缘电阻值。
在本申请的一些实施例中，在步骤S610中，首先获取第一采样信号相对于第二采样信号的第一相移。然后根据第一采样信号的第一电压幅值、第二采样信号的第二电压幅值、第一相移以及调整前注入信号的频率，得到电容值。
其中，电容模块的电容值的具体计算方法可参照公式(1)至公式(8)，在此不再赘述。
在步骤S620中，若电容值大于第一预设阈值，则减小注入信号的频率，以提高电容模块的容抗值，从而提高绝缘检测的精度。
在一些实施例中，若电容值小于第二预设阈值，则增大注入信号的频率，以提高绝缘电阻值的检测速度。
在步骤S630中，首先获取第三采样信号相对于第四采样信号的第二相移。然后根据第三采样信号的第三电压幅值、第四采样信号的第四电压幅值、第二相移以及调整后注入信号的频率，得到绝缘电阻值。绝缘电阻值的具体计算方法可参照公式(9)和公式(10)，在此不再赘述。
本申请实施例提供的绝缘检测方法，在电容模块的电容值较大的时候，降低注入信号的频率以提高电容模块的容抗值，从而降低电容模块的容抗值对Cnp和Rnp的并联阻抗Z的影响，以提高绝缘检测的精度。并且，在电容模块的电容值较小时，可以提高注入信号的频率，以降低绝缘电阻值的更新时间。
通过本申请实施例提供的绝缘检测方法，可以根据不同的应用场景调整注入信号的频率，即可以针对于不同的车型，针对不同的整车Y电容来 决定注入信号的频率选择，从而保证绝缘阻值精度消除由于整车Y电容引起的绝缘阻值偏低的问题。
并且，本申请实施例提供的绝缘检测电路和检测方法，还提高了整车的安全性能，同时，通过调整注入信号频率还可以提高整车的稳定性，消除因绝缘阻值测量精度导致绝缘误报等问题。
需要明确的是，本说明书中的各个实施例均采用递进的方式描述，各个实施例之间相同或相似的部分互相参见即可，每个实施例重点说明的都是与其他实施例的不同之处。对于绝缘检测方法的实施例而言，相关之处可以参见绝缘检测电路的说明部分。本申请并不局限于上文所描述并在图中示出的特定步骤和结构。本领域的技术人员可以在领会本申请的精神之后，作出各种改变、修改和添加，或者改变步骤之间的顺序。并且，为了简明起见，这里省略对已知方法技术的详细描述。
虽然已经参考优选实施例对本申请进行了描述，但在不脱离本申请的范围的情况下，可以对其进行各种改进并且可以用等效物替换其中的部件。尤其是，只要不存在结构冲突，各个实施例中所提到的各项技术特征均可以任意方式组合起来。本申请并不局限于文中公开的特定实施例，而是包括落入权利要求的范围内的所有技术方案。

Claims (16)

  1. 一种绝缘检测电路，其中，所述电路包括：
    第一隔离模块，分别与待测动力电池的正极和采样模块的一端连接；
    所述采样模块，所述采样模块的另一端与信号发生模块的一端连接；
    所述信号发生模块，所述信号发生模块的另一端与电源地连接，用于向所述待测动力电池提供注入信号；
    处理模块，用于根据从所述采样模块的一端采集的第一采样信号和从所述信号发生模块的一端采集的第二采样信号，确定所述待测动力电池和所述电源地之间的电容模块的电容值，并基于所述电容值调整所述注入信号的频率；
    所述处理模块还用于在调整所述注入信号的频率之后，根据从所述采样模块的一端采集的第三采样信号、从所述信号发生模块的一端采集的第四采样信号以及调整后的所述注入信号的频率，得出所述待测动力电池的绝缘电阻值。
  2. 根据权利要求1所述的电路，其中，所述处理模块具体用于若所述电容值大于第一预设阈值，则减小所述注入信号的频率。
  3. 根据权利要求1所述的电路，其中，所述处理模块具体用于若所述电容值小于第二预设阈值，则增大所述注入信号的频率。
  4. 根据权利要求1所述的电路，其中，所述处理模块具体用于获取所述第一采样信号相对于所述第二采样信号的第一相移，并根据所述第一采样信号的第一电压幅值、所述第二采样信号的第二电压幅值、所述第一相移以及调整前所述注入信号的频率，得到所述电容值。
  5. 根据权利要求1所述的电路，其中，所述处理模块具体用于获取所述第三采样信号相对于所述第四采样信号的第二相移，并根据所述第三采样信号的第三电压幅值、所述第四采样信号的第四电压幅值、所述第二相移以及调整后所述注入信号的频率，得到所述绝缘电阻值。
  6. 根据权利要求1所述的电路，其中，所述电路还包括：
    第一采样电路，所述第一采样电路的第一端与所述采样模块的一端连接，所述第一采样电路的第二端与所述处理模块连接，所述第一采样电路用于从所述采样模块的一端采集所述第一采样信号和所述第三采样信号。
  7. 根据权利要求6所述的电路，其中，所述电路还包括：
    第一滤波模块，分别与所述采样模块的一端和第二隔离模块连接；
    所述第二隔离模块，与所述第一采样电路连接，所述第二隔离模块用于隔离所述第一采样电路对所述第一采样信号和所述第三采样信号的干扰。
  8. 根据权利要求7所述的电路，其中，所述第二隔离模块包括：
    第一电压跟随器，所述第一电压跟随器的第一输入端与所述第一滤波模块连接，所述第一电压跟随器的输出端分别与所述第一电压跟随器的第二输入端和所述第一采样电路连接。
  9. 根据权利要求1所述的电路，其中，所述电路还包括：
    第二采样电路，所述第二采样电路的第一端与所述信号发生模块的一端连接，所述第二采样电路的第二端与所述处理模块连接，所述第二采样电路用于从所述信号发生模块的一端采集所述第二采样信号和所述第四采样信号。
  10. 根据权利要求9所述的电路，其中，所述电路还包括：
    第二滤波模块，分别与所述信号发生模块的一端和第三隔离模块连接；
    所述第三隔离模块，与所述第二采样电路连接，所述第三隔离模块用于隔离所述第二采样电路对所述第二采样信号和所述第四采样信号的干扰。
  11. 根据权利要求10所述的电路，其中，所述第三隔离模块包括：
    第二电压跟随器，所述第二电压跟随器的第一输入端与所述第二滤波模块连接，所述第二电压跟随器的输出端分别与所述第二电压跟随器的第二输入端和所述第二采样电路连接。
  12. 一种电池管理系统，其中，包括如权利要求1-11任意一项所述的绝缘检测电路。
  13. 一种绝缘检测方法，应用于如权利要求1-11任意一项所述的绝缘检测电路，其中，所述方法包括：
    根据从所述采样模块的一端采集的第一采样信号和从所述信号发生模块的一端采集的第二采样信号，确定所述待测动力电池和所述电源地之间的电容模块的电容值；
    基于所述电容值调整所述注入信号的频率；
    根据从所述采样模块的一端采集的第三采样信号、从所述信号发生模块的一端采集的第四采样信号以及调整后的所述注入信号的频率，得出所述待测动力电池的绝缘电阻值。
  14. 根据权利要求13所述的方法，其中，所述基于所述电容值调整所述注入信号的频率，包括：
    若所述电容值大于第一预设阈值，则减小所述注入信号的频率。
  15. 根据权利要求13所述的方法，其中，所述基于所述电容值调整所述注入信号的频率，包括：
    若所述电容值小于第二预设阈值，则增大所述注入信号的频率。
  16. 根据权利要求13所述的方法，其中，所述根据从所述采样模块的一端采集的第一采样信号和从所述信号发生模块的一端采集的第二采样信号，确定所述待测动力电池和所述电源地之间的电容模块的电容值，包括：
    获取所述第一采样信号相对于所述第二采样信号的第一相移；
    根据所述第一采样信号的第一电压幅值、所述第二采样信号的第二电压幅值、所述第一相移以及调整前所述注入信号的频率，得到所述电容值。
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CN107991625A (zh) * 2017-11-29 2018-05-04 四川长虹电器股份有限公司 动力蓄电池系统绝缘电阻检测电路与检测方法
CN108333492A (zh) * 2018-02-01 2018-07-27 宁德时代新能源科技股份有限公司 绝缘检测电路及方法、电池管理系统
CN108445397A (zh) * 2018-02-01 2018-08-24 宁德时代新能源科技股份有限公司 绝缘检测电路的参数选取方法和装置、存储介质

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