A method of detection

Abstract

The embodiment of the application provides a detection device and a detection method, and belongs to the technical field of batteries. The detection device is used for detecting a passive equalization circuit. The detection device comprises a plurality of detection units connected in series. The detection unit comprises a conversion assembly, a voltage follower, a detector and an isolated power supply. The conversion assembly is used for converting a received voltage value into a corresponding voltage. The input end of the voltage follower is electrically connected with the output end of the conversion assembly. The detector is electrically connected with the output end of the voltage follower, and the detector detects the voltage and current output by the voltage follower. The isolated power supply is electrically connected with the conversion assembly and the voltage follower respectively, and the isolated power supply supplies power to the conversion assembly and the voltage follower respectively. The output end of the voltage follower of one of the two detection units connected in series is electrically connected with the common end of the isolated power supply of the other detection unit. The detection device and the detection method of the embodiment of the application can adapt the detection device to the detection requirements of different output voltages.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of battery, in particular to a detection device and a detection method. BACKGROUND

[0002] After the electric vehicle is used for a period of time, due to the differences between the single batteries, the battery wear degrees are inconsistent, and the battery capacity differences will gradually increase, resulting in the gradual reduction of the electric vehicle mileage. The battery management system can use a passive equalization circuit to balance the differences between the single batteries. In the related art, the detection device for detecting the passive equalization circuit of the battery management system is inconvenient to use. SUMMARY

[0003] Therefore, the embodiments of the present application aim to provide a detection device and a detection method, so that the detection device can conveniently detect the passive equalization circuit.

[0004] To achieve the above-mentioned purpose, a first aspect of the embodiments of the present application provides a detection device for detecting a passive equalization circuit of a battery management system, the detection device comprising a plurality of detection units, the plurality of detection units being connected in series, and each detection unit comprising:

[0005] a conversion assembly configured to convert a received voltage value into a corresponding voltage;

[0006] a voltage follower, an input end of the voltage follower being electrically connected to an output end of the conversion assembly;

[0007] a detector, an output end of the voltage follower being electrically connected to the detector, and the detector being configured to detect the voltage and the current output by the voltage follower;

[0008] an isolation power supply, the isolation power supply being electrically connected to the conversion assembly and the voltage follower respectively, and the isolation power supply being configured to supply power to the conversion assembly and the voltage follower respectively;

[0009] In the two detection units connected in series, the output end of the voltage follower of one of the detection units is electrically connected to a common end of the isolation power supply of the other detection unit.

[0010] In an embodiment, the conversion assembly comprises:

[0011] a first controller configured to receive a voltage value, the isolation power supply being electrically connected to the first controller to supply power to the first controller;

[0012] a digital-to-analog converter, an input end of the digital-to-analog converter being electrically connected to an output end of the first controller, and an output end of the digital-to-analog converter being electrically connected to an input end of the voltage follower, the digital-to-analog converter being configured to convert the voltage value received by the first controller into a corresponding voltage.

[0013] In one embodiment, the input terminals of all the isolated power supplies are electrically connected.

[0014] In one embodiment, the voltage follower is an emitter follower.

[0015] Embodiments of the present application provide a detection method, applied to a detection assembly, the detection assembly comprising a battery management system and any one of the detection devices described above, the detection device and a passive equalization circuit of the battery management system being electrically connected, the detection method comprising:

[0016] closing an equalization switch of the battery management system in a test phase;

[0017] when the value of the first voltage is not equal to the voltage value received by the conversion component in the test phase, determining that the detection device has a first voltage output failure, the voltage value received by the conversion component in the test phase being a test voltage value, the first voltage being a voltage measured by the detector under a first condition, the first condition being that the equalization switch is closed and the voltage value received by the conversion component is the test voltage value;

[0018] determining a first current according to the maximum output current of the voltage follower;

[0019] when the difference between the second current and the third current is greater than or equal to the first current, determining that the passive equalization circuit fails, the second current being a current measured by the detector under the first condition, the third current being a current measured by the detector under a second condition, the second condition being that the equalization switch is open, the voltage value received by the conversion component is the test voltage value, and the working loop of the battery management system is not short-circuited;

[0020] when the passive equalization circuit fails or the detection device has the first voltage output failure, ending the detection.

[0021] In one embodiment, the absolute value of the difference between the maximum output current of the voltage follower and the third current is a reference current, the first current is greater than or equal to the difference between the reference current and a tolerance current, and the first current is less than or equal to the sum of the reference current and the tolerance current.

[0022] In one embodiment, the detection method further comprises:

[0023] when the value of the voltage measured by the detector under the third condition is not equal to the test voltage value, determining that the detection device has a second voltage output failure;

[0024] determining that the power management system has an overcurrent fault when the current measured by the detector corresponding to the third condition is greater than or equal to a third battery, the third condition being that the balancing switch corresponding to the equalization switch is open and the voltage value received by the conversion assembly corresponding to the test voltage value;

[0025] stopping the detection when the power management system has an overcurrent fault or the detection device has a second voltage output fault.

[0026] In an embodiment, before the conversion assembly receives the test voltage value in the test phase, the detection method further comprises:

[0027] determining that the detection device has a self-calibration voltage fault when the voltage value measured by the detector corresponding to the fourth condition is not equal to a default voltage value, the default voltage value being the voltage value received by the conversion assembly in the self-calibration phase, and the fourth condition being that the voltage value received by the conversion assembly corresponding to the default voltage value;

[0028] stopping the detection when the detection device has a self-calibration fault.

[0029] In an embodiment, before the conversion assembly receives the default voltage value in the self-calibration phase, the detection method further comprises:

[0030] performing a power-on self-test on the detection device in the self-test phase;

[0031] stopping the detection when the detection device has a self-test fault.

[0032] In an embodiment, closing the balancing switch of the battery management system in the test phase comprises: sequentially closing one of all the balancing switches in the test phase.

[0033] The detection device of the embodiment of the application, the isolation power supply is used to isolate the internal power supply of each detection unit from the external power supply, a common terminal serving as a reference potential can be formed in each detection unit, and the common terminals of each detection unit are independent, and the potentials of the common terminals of different detection units can be different, so that the detection units can be connected in series. Each detection unit is used to simulate a single battery of a battery electric vehicle, and the detection units are connected in series to simulate a series connection of single batteries of a battery electric vehicle. In each detection unit, the isolation power supply and the voltage follower can output a voltage corresponding to the voltage value received by the conversion assembly. The output voltage of the voltage follower changes according to the change of the voltage value received by the conversion assembly, and the output voltage of the voltage follower can be adjusted according to actual needs, so that the detection device can detect the passive equalization circuit with a required voltage, and the detection device can adapt to the detection requirements of different output voltages. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 A structure diagram of a detection device according to an embodiment of the present application;

[0035] Figure 2 A circuit wiring diagram of an isolation power supply, a digital-to-analog converter, a voltage follower and a detector according to an embodiment of the present application;

[0036] Figure 3 A flowchart of a detection method according to an embodiment of the present application, in which the balancing switch is closed in the test phase;

[0037] Figure 4 A flowchart of a detection method according to an embodiment of the present application, in which one of all the balancing switches is closed in the test phase in turn;

[0038] Figure 5 A flowchart of a detection method according to an embodiment of the present application, in which the balancing switch is disconnected in the test phase;

[0039] Figure 6 A self-calibration flowchart of a detection method according to an embodiment of the present application;

[0040] Figure 7 A self-detection flowchart of a detection method according to an embodiment of the present application;

[0041] Figure 8 A flowchart of a detection method according to an embodiment of the present application, which shows the whole process from powering on the detection device to ending the detection.

[0042] Legend: host computer 100; detection device 200; detection unit 201; battery management system 300; second controller 301; balancing switch 302; balancing resistor 303; external power supply 400; conversion assembly 1; first controller 11; digital-to-analog converter 12; voltage follower 2; detector 3; isolation power supply 4; common terminal 41. DETAILED DESCRIPTION

[0043] It should be noted that the embodiments in the present application and the technical features in the embodiments can be combined with each other without conflict, and the detailed description in the specific embodiments should be understood as the explanation and description of the purpose of the present application, and should not be regarded as improper limitation of the present application.

[0044] In the related art, the detection device for detecting the passive balancing circuit of the battery management system is powered by a battery pack, and the voltage directly output by the battery pack cannot be basically adjusted, which is difficult to adapt to the detection requirements of different output voltages, and thus is not changed.

[0045] In view of this, the present application provides a detection assembly, please refer to Figure 1The detection assembly comprises the battery management system 300 and the detection device 200, and the passive equalization circuit of the battery management system 300 is electrically connected with the detection device 200.

[0046] The detection device 200 of the embodiment of the application is used for detecting the passive equalization circuit of the battery management system 300.

[0047] The battery management system 300 of the embodiment of the application, please refer to Figure 1 The battery management system 300 comprises a second controller 301 and passive equalization circuits electrically connected with the second controller 301, the number of the passive equalization circuits is multiple, each passive equalization circuit comprises an equalization switch 302 and an equalization resistor 303 connected with each other in series, each equalization switch 302 is used for controlling the corresponding passive equalization circuit to be closed or opened. The second controller 301 is used for controlling the equalization switch 302 to be closed or opened.

[0048] It should be noted that multiple means more than two and includes two.

[0049] In an embodiment, please refer to Figure 1 The detection assembly further comprises a host computer 100, the host computer 100 is electrically connected with the second controller 301, the second controller 301 closes and / or opens the corresponding equalization switch 302 according to the received switch instruction, and the switch instruction is sent through the host computer 100.

[0050] In an embodiment, the battery management system 300 further comprises multiple working loops (not shown in the figure), each working loop is connected with the corresponding passive equalization loop in parallel.

[0051] The detection device 200 of the embodiment of the application, please refer to Figure 1 The detection device 200 comprises multiple detection units 201, and the multiple detection units 201 are connected in series.

[0052] In an embodiment, please refer to Figure 1 And Figure 2The detection unit 201 comprises a conversion assembly 1, a voltage follower 2, a detector 3 and an isolated power supply 4. The conversion assembly 1 is used to convert the received voltage value into a corresponding voltage. The input end of the voltage follower 2 is electrically connected with the output end of the conversion assembly 1. The detector 3 is electrically connected with the output end of the voltage follower 2, and the detector 3 is used to detect the voltage and current output by the voltage follower 2. The isolated power supply 4 is electrically connected with the conversion assembly 1 and the voltage follower 2 respectively, and the isolated power supply 4 is used to supply power to the conversion assembly 1 and the voltage follower 2 respectively. In two adjacent detection units 201 in series, the output end of the voltage follower 2 of one detection unit 201 is electrically connected with the common end 41 of the isolated power supply 4 of the other detection unit 201. In this structure, the isolated power supply 4 is used to isolate the internal power supply of each detection unit 201 from the external power supply 400, and the common end 41 can be formed as a reference potential in each detection unit 201, and the common end 41 of each detection unit 201 is independent, and the potentials of the common ends 41 of different detection units 201 can be different, so that the detection units 201 can be connected in series, and each detection unit 201 is used to simulate a single battery of a battery car, and the detection units 201 are connected in series to simulate a series connection of single batteries of a battery car. In each detection unit 201, the isolated power supply 4 and the voltage follower 2 can output a voltage corresponding to the voltage value received by the conversion assembly 1, and the voltage output by the voltage follower 2 changes according to the change of the voltage value received by the conversion assembly 1, and the output voltage of the voltage follower 2 can be adjusted according to actual needs, so that the detection device 200 can detect the passive equalization circuit with the required voltage, and the detection device 200 can adapt to the detection needs of different output voltages.

[0053] It can be understood that the potential of the common end 41 of the isolated power supply 4 can be understood as a reference potential in the detection unit 201. When the power output by the isolated power supply 4 is direct current, the common end 41 of the isolated power supply 4 is the negative electrode of the isolated power supply 4, and when the power output by the isolated power supply 4 is alternating current, the common end 41 of the isolated power supply 4 is the zero line of the isolated power supply 4. In each detection unit 201, the voltage corresponding to the voltage of the isolated power supply 4, the voltage loaded on the input end of the voltage follower 2 after conversion by the conversion assembly 1 and the voltage of the output end of the voltage follower 2 are all referenced to the common end 41 of the isolated power supply 4.

[0054] It can be understood that the voltage output by the voltage follower 2 is used to detect the passive equalization circuit, and the battery pack for outputting the required voltage for detection can not be additionally arranged in each detection unit 201, which reduces the charging operation of the operator and is more convenient to use.

[0055] In an embodiment, the operator can input the required voltage value for detection through the host computer 100, and the host computer 100 sends the set voltage value to the conversion assembly 1. The conversion assembly 1 receives the voltage value sent by the host computer 100. The conversion assembly 1 converts the received voltage value sent by the host computer 100 into a corresponding voltage.

[0056] In an embodiment, the detection device 200 further comprises an input device for setting the voltage value, and the operator can input the required voltage value for detection through the input device, and the input device sends the set voltage value to the conversion assembly 1.

[0057] In an embodiment, referring to Figure 1 and Figure 2 , the conversion assembly 1 comprises a first controller 11 and a digital-to-analog converter 12. The first controller 11 is used to receive the voltage value, and the isolation power supply 4 is electrically connected with the first controller 11 to supply power to the first controller 11. The input end of the digital-to-analog converter 12 is electrically connected with the output end of the first controller 11, and the output end of the digital-to-analog converter 12 is electrically connected with the input end of the voltage follower 2. The digital-to-analog converter 12 is used to convert the voltage value received by the first controller 11 into a corresponding voltage. In this structure, the first controller 11 receives the voltage value and issues a corresponding instruction to the digital-to-analog converter 12, which controls the digital-to-analog converter 12 to convert the digital quantity of the voltage value into the analog quantity of the corresponding voltage. Since the output end of the digital-to-analog converter 12 is electrically connected with the input end of the voltage follower 2, the converted analog quantity of the voltage is loaded on the input end of the voltage follower 2, so that the voltage output from the output end of the voltage follower 2 is basically the converted analog quantity of the voltage by the digital-to-analog converter 12. Through the reception of the voltage value by the first controller 11 and the conversion of the voltage value by the digital-to-analog converter 12, the set voltage value can be better converted into the voltage for detecting the passive equalization circuit.

[0058] In an embodiment, the host computer 100 sets the required voltage value for detecting the passive equalization circuit, and the host computer 100 sends the set voltage value to the first controller 11.

[0059] In an embodiment, the input device sets the required voltage value for detecting the passive equalization circuit, and the input device sends the set voltage value to the first controller 11.

[0060] In an embodiment, referring to Figure 1 , the input ends of all isolation power supplies 4 are electrically connected. In this structure, one external power supply 400 can supply power to all isolation power supplies 4 of the detection units 201, and it is not necessary to provide an external power supply 400 for each isolation power supply 4, which simplifies the structure of the detection device 200 and makes the detection device 200 more convenient to use.

[0061] In an embodiment, the external power supply 400 can be an alternating current with a voltage of 220V and a frequency of 50Hz, which is rectified by the rectifier into direct current to supply power to the isolation power supply 4.

[0062] In an embodiment, the voltage follower 2 is an emitter follower. In this form of structure, the input voltage of the emitter follower is the voltage across the base, the input current of the emitter follower is the current flowing through the base, the output voltage of the emitter follower is the voltage of the emitter, the output current of the emitter follower is the current output by the emitter, and the emitter current of the emitter follower is constrained by the base current and is in a multiple relationship. Even if the output end of the emitter follower is short-circuited, the maximum current output by the emitter will be constrained, and the possibility of further damage to the load of the output end of the emitter follower in the case of a short-circuit fault can be reduced.

[0063] An embodiment of the present application provides a detection method, please refer to Figure 3 The detection method is applied to a detection assembly, the detection assembly includes the battery management system 300 and the detection device 200 of any one of the above embodiments, and the passive equalization circuit of the detection device 200 and the battery management system 300 are electrically connected. The detection method includes the following steps:

[0064] Step S1, closing the equalization switch 302 of the battery management system 300 in the test phase;

[0065] Step S2, when the value of the first voltage is not equal to the voltage value received by the conversion assembly 1 in the test phase, it is determined that the detection device 200 has a first voltage output fault.

[0066] It should be noted that the voltage value received by the conversion assembly 1 in the test phase is a test voltage value, and the first voltage is the voltage measured by the detector 3 under the first condition, and the first condition is that the equalization switch 302 is closed and the voltage value received by the conversion assembly 1 is the test voltage value.

[0067] Exemplarily, the test voltage value can be 3.7V.

[0068] The output voltage of the detection device 200 is detected in the case of closing the equalization switch 302, and by detecting the output voltage of the detection device 200, it can be known whether the detection device 200 has a first voltage output fault.

[0069] In an embodiment, please refer to Figure 3 The detection method further includes the following steps:

[0070] Step S3, determining the first current according to the maximum output current of the corresponding voltage follower 2;

[0071] Step S4, when the difference between the second current and the third current is greater than or equal to the first current, it is determined that the passive equalization circuit has a fault.

[0072] It is to be explained that the second current is the current measured by the detector 3 under the first condition, and the third current is the current measured by the detector 3 under the second condition, the second condition being that the equalization switch 302 is open, the voltage value received by the conversion assembly 1 is the test voltage value, and the working loop of the battery management system 300 is not short-circuited.

[0073] It can be understood that the equalization switch 302 is open, the working loop (not shown in the figure) in parallel with the passive equalization circuit in the battery management system 300 is not open, and the third current is the current flowing through the working loop in parallel with the passive equalization circuit under the second condition. When the equalization switch 302 is closed, the current flowing through the working loop will still flow through the detector 3 as part of the current detected by the detector 3.

[0074] It can be understood that there is no sequence between step S1 and steps S3 and S4.

[0075] It can be understood that there is no sequence between step S2 and steps S3 and S4.

[0076] In an embodiment, the third current can be 10 mA.

[0077] The output current of the detection device 200 is detected when the equalization switch 302 is closed, and whether the passive equalization circuit is faulty can be known by detecting the output current of the detection device 200. For example, when the passive equalization circuit has a short-circuit fault, the second current measured by the detector 3 under the first condition is large, and the difference between the second current and the third current will be greater than or equal to the first current.

[0078] It is to be noted that the voltage follower 2 is one of the operational amplifiers, the maximum output current of the voltage follower 2 represents the driving capability of the voltage follower 2, and the maximum output current of the voltage follower 2 is the current measured when the output end of the voltage follower 2 is short-circuited. For example, the output end of the voltage follower 2 is short-circuited to the common end 41 of the power supply, and the current at the output end of the voltage follower 2 is the maximum output current.

[0079] For example, the maximum output current of the voltage follower 2 is 100 mA.

[0080] It can be understood that when the difference between the second current and the third current is greater than or equal to the first current, it is determined that the passive equalization circuit is faulty, and the passive equalization circuit is short-circuited.

[0081] In an embodiment, referring to Figure 3 , the detection method further comprises:

[0082] Step S5, when the passive equalization circuit fails or the detection device 200 has a first voltage output fault, the detection ends.

[0083] In this way, the detection stops when a corresponding fault exists, which can better protect the detection device 200 and the battery management system 300 and reduce the possibility of further damage to the detection device 200 and the battery management system 300.

[0084] In an embodiment, the absolute value of the difference between the maximum output current of the voltage follower 2 and the third current is a reference current, the first current is greater than or equal to the difference between the reference current and a tolerance current, and the first current is less than or equal to the sum of the reference current and the tolerance current. In this way, the absolute value of the difference between the second current and the third current is approximately the current flowing through the passive equalization circuit, and the absolute value of the difference between the maximum output current of the voltage follower 2 and the third current reflects the maximum current flowing through the passive equalization circuit, which can more accurately reflect the current situation of the passive equalization circuit and provide a more accurate basis for the fault judgment of the passive equalization circuit. Considering the measurement error, the range of the first current is limited by the tolerance current, which reduces the influence of the measurement error on the fault judgment.

[0085] For example, the maximum output current of the voltage follower 2 is 100 mA, the third current is 10 mA, and the tolerance current is 10 mA. The first current is greater than or equal to [(100 mA-10 mA)-10 mA], and the first current is less than or equal to [(100 mA-10 mA)+10 mA].

[0086] For example, the maximum output current of the voltage follower 2 is 100 mA, the third current is 10 mA, and the tolerance current is 5 mA. The first current is greater than or equal to [(100 mA-10 mA)-5 mA], and the first current is less than or equal to [(100 mA-10 mA)+5 mA].

[0087] In an embodiment, referring to Figure 5 , the detection method further comprises:

[0088] Step S6, when the value corresponding to the voltage measured by the detector 3 under the third condition is not equal to the test voltage value, it is determined that the detection device 200 has a second voltage output fault;

[0089] Step S7, when the current corresponding to the detector 3 measured under the third condition is greater than or equal to the third current, it is determined that the power management system has a current overload fault.

[0090] It should be noted that the third condition is that the equalization switch 302 is open and the voltage value received by the conversion assembly 1 is the test voltage value.

[0091] It should be noted that the power management system has a current overlarge fault, and a working loop in parallel with the passive balancing circuit in the power management system is short-circuited.

[0092] Exemplarily, the third current is 10 mA, and when the current measured by the corresponding detector 3 under the third condition is greater than or equal to 10 mA, the power management system has a current overlarge fault.

[0093] The detection of the current and the voltage under the conditions that the balancing switch 302 is closed and opened respectively can better identify specific faults.

[0094] It can be understood that there is no sequence between the step S6 and the step S7.

[0095] In an embodiment, referring to Figure 5 , the detection method further comprises:

[0096] The step S8, when the power management system has a current overlarge fault or the detection device 200 has a second voltage output fault, the detection is ended. In this way, the detection is stopped when there is a corresponding fault, which can better protect the detection device 200 and the battery management system 300, and reduce the possibility of further damage to the detection device 200 and the battery management system 300.

[0097] In an embodiment, referring to Figure 6 , before the conversion assembly 1 receives the test voltage value in the test stage, the detection method further comprises:

[0098] The step S9, when the value of the voltage measured by the corresponding detector 3 under the fourth condition is not equal to the default voltage value, it is determined that the detection device 200 has a self-calibration voltage fault.

[0099] It should be explained that the default voltage value is the voltage value received by the conversion assembly 1 in the self-calibration stage, and the fourth condition is that the voltage value received by the conversion assembly 1 is the default voltage value.

[0100] The conversion assembly 1 can perform self-calibration of the voltage to calibrate the voltage loaded to the input end of the voltage follower 2 to the received voltage value, and when the value of the voltage at the output end of the voltage follower 2 is not equal to the received voltage value, the conversion assembly 1 has a self-calibration fault.

[0101] The conversion assembly 1 performs self-calibration of the voltage through the digital-to-analog converter 12.

[0102] In an embodiment, referring to Figure 6 , before the conversion assembly 1 receives the test voltage value in the test stage, the detection method further comprises:

[0103] Step S10, when the detection device 200 has a self-calibration fault, end the detection. In this way, stop the detection when there is a corresponding fault, which can better protect the detection device 200 and the battery management system 300, and reduce the possibility of further damage to the detection device 200 and the battery management system 300.

[0104] In an embodiment, referring to Figure 7 , before the detection device 200 receives the default voltage value in the self-calibration phase, the detection method further comprises:

[0105] Step S11, power-on self-test of the detection device 200 in the self-test phase;

[0106] Step S12, when the detection device 200 has a self-test fault, end the detection.

[0107] Before calibration, the detection device 200 performs self-test to ensure that the hardware and software of the detection device 200 are running normally.

[0108] In an embodiment, referring to Figure 4 , the equalization switch 302 of the battery management system 300 is closed in the test phase, including:

[0109] Step S13, in the test phase, sequentially close one of the equalization switches 302.

[0110] In this way, each time one of the equalization switches 302 is closed, one of the passive equalization circuits is detected, which reduces the influence of other passive equalization circuits on the passive equalization circuit, and can more accurately identify the faults of each passive equalization circuit.

[0111] The specific detection process of the detection device 200 is illustrated by the following embodiment. Before the host computer 100 does not control any one of the equalization switches 302 to be closed, all the equalization switches 302 are open, and the equalization switches 302 are in a state that has not been closed. When the equalization switch 302 is closed and then opened, the equalization switch 302 is in a state that has been closed.

[0112] Referring to Figure 8 , the detection method comprises:

[0113] Step S201, power on the detection device 200;

[0114] Step 202, determine whether the detection device 200 has a self-test fault, if yes, execute step S203, if no, execute step S204;

[0115] Step S203, determine that the detection device 200 has a self-test fault, and execute step S219;

[0116] Step S204, sending the default voltage value to the first controller 11 through the host computer 100;

[0117] Step S205, judging whether the value of the voltage detected by the detector 3 is equal to the default voltage value, if yes, executing step S207, if not, executing step S206;

[0118] Step S206, determining that the self-calibration of the detection device 200 fails, and executing step S219;

[0119] Step S207, sending the test voltage value to the first controller 11 through the host computer 100;

[0120] Step S208, judging whether the value of the voltage detected by the detector 3 is equal to the test voltage value, if yes, executing step S210, if not, executing step S209;

[0121] Step S209, determining that the detection device 200 has a second voltage fault, and executing step S219;

[0122] Step S210, judging whether the current detected by the detector 3 is greater than or equal to the third current, if yes, executing step S211, if not, executing step S212;

[0123] Step S211, determining that the power management system has an excessive current fault, and executing step S219;

[0124] Step S212, closing one of the equalization switches 302 that has not been closed yet through the host computer 100;

[0125] Step S213, judging whether the voltage detected by the detector 3 is equal to the test voltage value, if yes, executing step S215, if not, executing step S214;

[0126] Step S214, determining that the detection device 200 has a first voltage output fault, and executing step S219;

[0127] Step S215, judging whether the difference between the current detected by the detector 3 and the third current is greater than or equal to the first current, if yes, executing step S216, if not, executing step S217;

[0128] Step S216, determining that the passive equalization circuit corresponding to the closed equalization switch 302 has a fault, and executing step S219;

[0129] Step S217, judging whether all the equalization switches 302 have been closed, if yes, executing step S218, if not, executing step S212;

[0130] Step S218, determining that the detection is successful;

[0131] Step S219, end the detection.

[0132] The various embodiments / implementation provided in the present application can be combined with each other without producing contradictions, if possible.

[0133] The above only is the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A detection method, characterized in that, The device is applied to a testing assembly, which includes a battery management system and a testing device. The testing device is electrically connected to the passive balancing circuit of the battery management system. The testing device is used to test the passive balancing circuit of the battery management system. The testing device includes multiple testing units connected in series. Each testing unit includes: A conversion component is used to convert the received voltage value into a corresponding voltage. A voltage follower, wherein the input terminal of the voltage follower is electrically connected to the output terminal of the conversion component; A detector is electrically connected to the output terminal of the voltage follower, and the detector is used to detect the voltage and current output by the voltage follower; An isolated power supply is electrically connected to both the conversion component and the voltage follower, and the isolated power supply is used to supply power to both the conversion component and the voltage follower. In two adjacent detection units connected in series, the output terminal of the voltage follower of one detection unit is electrically connected to the common terminal of the isolation power supply of the other detection unit; The detection method includes: During the testing phase, the equalization switch of the battery management system is closed; When the value of the first voltage is not equal to the voltage value received by the conversion component during the test phase, it is determined that the detection device has a first voltage output fault. The voltage value received by the conversion component during the test phase is the test voltage value. The first voltage is the voltage measured by the detector under the first condition. The first condition is that the equalization switch is closed and the voltage value received by the conversion component is the test voltage value. The first current is determined based on the maximum output current of the corresponding voltage follower; When the difference between the second current and the third current is greater than or equal to the first current, the passive equalization circuit is determined to be faulty. The second current is the current measured by the detector under the first condition, and the third current is the current measured by the detector under the second condition. The second condition is that the equalization switch is open, the voltage received by the conversion component is the test voltage value, and the working circuit of the battery management system is not short-circuited. The detection ends when the passive equalization circuit fails or the detection device has a first voltage output failure.

2. The detection method according to claim 1, characterized in that, The conversion component includes: A first controller is used to receive voltage values, and the isolated power supply is electrically connected to the first controller to supply power to the first controller; A digital-to-analog converter (DAC) is provided, wherein the input terminal of the DAC is electrically connected to the output terminal of the first controller, and the output terminal of the DAC is electrically connected to the input terminal of the voltage follower. The DAC is used to convert the voltage value received by the first controller into a corresponding voltage.

3. The detection method according to claim 1 or 2, characterized in that, All of the aforementioned isolated power supplies are electrically connected to their input terminals.

4. The detection method according to claim 1 or 2, characterized in that, The voltage follower is an emitter follower.

5. The detection method according to claim 1, characterized in that, The absolute value of the difference between the maximum output current of the voltage follower and the third current is the reference current. The first current is greater than or equal to the difference between the reference current and the tolerance current, and the first current is less than or equal to the sum of the reference current and the tolerance current.

6. The detection method according to claim 1, characterized in that, The detection method further includes: If the voltage value measured by the detector under the third condition is not equal to the test voltage value, it is determined that the detection device has a second voltage output fault. When the current measured by the detector under the third condition is greater than or equal to the third current, it is determined that there is an excessive current fault in the power management system. The third condition is that the equalization switch is open and the voltage received by the conversion component is the test voltage value. The detection ends when the power management system has an excessive current fault or the detection device has a second voltage output fault.

7. The detection method according to claim 6, characterized in that, Before receiving the test voltage value using the conversion component during the testing phase, the detection method further includes: When the voltage value measured by the detector under the fourth condition is not equal to the default voltage value, it is determined that the detection device has a self-calibration voltage fault. The default voltage value is the voltage value received by the conversion component during the self-calibration phase, and the fourth condition is the voltage value received by the conversion component as the default voltage value. The detection process ends when the detection device experiences a self-calibration failure.

8. The detection method according to claim 7, characterized in that, Before receiving the default voltage value during the self-calibration phase using the conversion component, the detection method further includes: During the self-test phase, the detection device undergoes a power-on self-test. If the detection device has a self-test fault, the detection ends.

9. The detection method according to any one of claims 1 to 8, characterized in that, Closing the equalization switch of the battery management system during the testing phase includes: sequentially closing one of the equalization switches among all the equalization switches during the testing phase.

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