High-voltage acquisition self-checking circuit, battery management system and vehicle

Abstract

The utility model provides a high-voltage acquisition self-checking circuit, a battery management system and a vehicle. The circuit comprises a battery pack cut-off sub-circuit, a low-voltage source access sub-circuit and a comparison detection sub-circuit, the battery pack cut-off sub-circuit is respectively connected with the battery pack and the high-voltage acquisition loop, the low-voltage source access sub-circuit is respectively connected with the low-voltage power supply and the high-voltage acquisition loop, and the comparison detection sub-circuit is connected with a sampling resistor in the high-voltage acquisition loop; in a high-voltage acquisition abnormal state, the battery pack cut-off sub-circuit disconnects the battery pack from the high-voltage acquisition loop according to the received first group of control signals; the low-voltage source access sub-circuit accesses a low-voltage power supply to the high-voltage acquisition loop according to the received second group of control signals; the comparison detection sub-circuit compares the voltage value of the sampling resistor with a voltage upper limit value and a voltage lower limit value and then outputs a self-check level signal used for representing a self-check result. According to the scheme, the self-checking function of a high-voltage acquisition link is realized, and the reliability is higher.

Description

Technical Field

[0001] The utility model relates to the technical field of battery management, in particular to a high-voltage acquisition self-checking circuit, a battery management system and a vehicle. Background Art

[0002] During the charging and discharging process of the battery pack, the normality of the high-voltage circuit will directly affect the safety of the entire charging and discharging process. Therefore, the high-voltage monitoring of the battery pack is particularly important.

[0003] In the related art, the high-voltage monitoring of the battery pack is usually realized by using a high-voltage acquisition circuit. Specifically, the relatively large voltage output by the battery pack can be changed into a smaller voltage by means of resistor voltage division. By obtaining the voltage value divided by the sampling resistor and through certain conversion processing, the high-voltage acquisition of the battery pack is realized.

[0004] In practical applications, the abnormal high-voltage acquisition during the high-voltage acquisition process is usually caused by various reasons. For example, the voltage-dividing resistor, the sampling resistor or the acquisition chip fails, or the voltage of the battery pack rises due to abnormal load. However, the traditional high-voltage acquisition circuit can only detect the state of abnormal high-voltage sampling, but cannot determine the specific cause, resulting in the imperfect function and low reliability of the high-voltage acquisition link, thereby affecting the normal operation of the vehicle. Summary of the Utility Model

[0005] The utility model provides a high-voltage acquisition self-checking circuit, a battery management system and a vehicle to solve the defects that the traditional high-voltage acquisition circuit has imperfect function and low reliability.

[0006] On the one hand, the utility model provides a high-voltage acquisition self-checking circuit, which is applied to the high-voltage acquisition circuit of the battery pack. The circuit includes: a battery pack cut-off sub-circuit, a low-voltage source access sub-circuit and a comparison and detection sub-circuit;

[0007] The battery pack cut-off sub-circuit is respectively connected to the battery pack and the high-voltage acquisition circuit, the low-voltage source access sub-circuit is respectively connected to the low-voltage power supply and the high-voltage acquisition circuit, and the comparison and detection sub-circuit is connected to the sampling resistor in the high-voltage acquisition circuit;

[0008] In the state of abnormal high-voltage acquisition, the battery pack cut-off sub-circuit disconnects the battery pack from the high-voltage acquisition circuit according to the received first group of control signals; the low-voltage source access sub-circuit accesses the low-voltage power supply to the high-voltage acquisition circuit according to the received second group of control signals; after the comparison and detection sub-circuit compares the voltage value of the sampling resistor with the voltage upper limit value and the voltage lower limit value respectively, it outputs a self-check level signal for characterizing the self-check result.

[0009] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the battery pack cut-off sub-circuit includes: a first opto-coupler switch, a second opto-coupler switch, and a third opto-coupler switch;

[0010] The first opto-coupler switch is respectively connected to the positive electrode of the battery pack and the first end of the high-voltage acquisition circuit. The second opto-coupler switch is respectively connected to the negative electrode of the battery pack and the second end of the high-voltage acquisition circuit. The third opto-coupler switch is connected in the high-voltage acquisition circuit.

[0011] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the battery pack cut-off sub-circuit further includes: a first current-limiting resistor, a second current-limiting resistor, and a third current-limiting resistor;

[0012] The first current-limiting resistor is connected to the first opto-coupler switch. The second current-limiting resistor is connected to the second opto-coupler switch. The third current-limiting resistor is connected to the third opto-coupler switch.

[0013] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the low-voltage source access sub-circuit includes: a first MOS transistor, a second MOS transistor, and a triode;

[0014] The first MOS transistor is respectively connected to the low-voltage power supply and the high-voltage acquisition circuit. The triode is respectively connected to the low-voltage power supply and the first MOS transistor. The second MOS transistor is respectively connected to the high-voltage acquisition circuit and the ground terminal.

[0015] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the low-voltage source access sub-circuit further includes: a fourth current-limiting resistor;

[0016] The fourth current-limiting resistor is respectively connected to the low-voltage power supply and the collector of the triode.

[0017] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the comparison and detection sub-circuit includes: a comparison module and a trigger;

[0018] The comparison module is respectively connected to the sampling resistor and the trigger;

[0019] The comparison module is configured to compare the voltage value of the sampling resistor with the upper voltage limit value and then output a first result signal to the trigger. The comparison module is further configured to compare the voltage value of the sampling resistor with the lower voltage limit value and then output a second result signal to the trigger;

[0020] After receiving the first result signal and the second result signal, the trigger outputs a self-check level signal for characterizing the self-check result according to the level state of the first result signal and the level state of the second result signal.

[0021] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the comparison module includes: a first comparator and a second comparator;

[0022] The inverting input terminal of the first comparator and the non-inverting input terminal of the second comparator are both connected to the sampling resistor. The non-inverting input terminal of the first comparator is connected to the upper voltage limit value, the inverting input terminal of the second comparator is connected to the lower voltage limit value, and the output terminals of the first comparator and the second comparator are both connected to the trigger.

[0023] According to the high-voltage acquisition self-checking circuit provided by the present utility model, the comparison module further includes: a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor, and a fourth voltage-dividing resistor;

[0024] The first ends of the first voltage-dividing resistor and the second voltage-dividing resistor are both connected to the non-inverting input terminal of the first comparator. The second end of the first voltage-dividing resistor is connected to the low-voltage power supply, and the second end of the second voltage-dividing resistor is grounded;

[0025] The first ends of the third voltage-dividing resistor and the fourth voltage-dividing resistor are both connected to the inverting input terminal of the second comparator. The second end of the third voltage-dividing resistor is connected to the low-voltage power supply, and the second end of the fourth voltage-dividing resistor is grounded.

[0026] On the other hand, the present utility model further provides a battery management system, including any one of the above-mentioned high-voltage acquisition self-checking circuits.

[0027] On the other hand, the present utility model further provides a vehicle, including any one of the above-mentioned high-voltage acquisition self-checking circuits or the above-mentioned battery management system.

[0028] For the high-voltage acquisition self-checking circuit, battery management system, and vehicle provided by the present utility model, by setting a battery pack cut-off sub-circuit, a low-voltage source access sub-circuit, and a comparison and detection sub-circuit, in the case of an abnormal high-voltage acquisition state, the battery pack cut-off sub-circuit disconnects the battery pack from the high-voltage acquisition loop according to the received first set of control signals, thereby ensuring circuit safety. The low-voltage source access sub-circuit connects the low-voltage power supply to the high-voltage acquisition loop according to the received second set of control signals. After the comparison and detection sub-circuit compares the voltage value of the sampling resistor with the upper voltage limit value and the lower voltage limit value respectively, it outputs a self-check level signal for characterizing the self-check result. The self-check result can be determined according to the level state of the self-check level signal, so as to accurately know the reason for the abnormal high-voltage acquisition state, realizing the self-check function of the high-voltage acquisition link, with more perfect functions and higher reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] To more clearly illustrate the technical solutions in the present utility model or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present utility model. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0030] Figure 1 is a schematic structural diagram of a high-voltage acquisition circuit in the prior art;

[0031] Figure 2 is a schematic structural diagram of the high-voltage acquisition self-check circuit provided by the embodiment of the present utility model. Detailed implementation manners

[0032] To make the objectives, technical solutions and advantages of the present utility model clearer, the following will clearly and completely describe the technical solutions in the present utility model with reference to the drawings in the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. Based on the embodiments in the present utility model, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the protection scope of the present utility model.

[0033] This embodiment relates to the field of battery management and can be specifically applied to the high-voltage acquisition circuit in the high-voltage monitoring link of the battery pack. Currently, the mainstream high-voltage acquisition circuit generally uses the method of resistor voltage division to change the relatively large voltage output by the battery pack into a relatively small voltage, and then through the acquisition chip inside the BMS, the analog quantity is converted into a digital quantity, and then through the internal formula, it is converted into the original high-voltage value.

[0034] Figure 1 Exemplarily shows the basic structure of the high-voltage acquisition circuit. The high-voltage acquisition circuit includes a voltage-dividing resistor R1, a sampling resistor R2, and an acquisition chip U0. The voltage-dividing resistor R1 and the sampling resistor R2 are connected in series, and the series branch is connected in parallel with both ends of the positive and negative electrodes of the battery pack PACK. On the connection line between the battery pack PACK and the motor M or other loads, there are also a main positive contactor K z , a main negative contactor K f and a pre-charge circuit formed by the series connection of a pre-charge contactor K y and a pre-charge resistor R y .

[0035] In practical applications, when a high-voltage acquisition abnormal state is detected through the high-voltage acquisition circuit, it may be caused by any one of various reasons. These various reasons can generally be divided into the following two situations:

[0036] One situation is that the voltage-dividing resistor, sampling resistor, or acquisition chip in the high-voltage acquisition circuit fails. For example, if the resistance value of the sampling resistor has a positive offset (i.e., increases), the corresponding voltage-dividing value of the sampling resistor will increase accordingly, and the original high-voltage value calculated according to the internal formula of the BMS will also increase accordingly. When it increases to a certain extent, the high-voltage value will exceed the fault limit. Taking a 400V battery platform as an example, if the sampling resistor is too large, the calculated total voltage will be greater than 400V, and an overvoltage fault will be reported, making the vehicle unable to start.

[0037] Another situation is that the motor or other loads malfunction, causing abnormal charging back to the high-voltage circuit, which in turn causes the voltage of the battery pack to rise. Different from the previous situation, this voltage increase actually occurs, rather than being misreported due to the failure of some components in the high-voltage sampling circuit.

[0038] However, since the traditional high-voltage acquisition circuit cannot distinguish the above two situations, it is impossible to make corresponding judgments based on the two different situations. But the corresponding fault levels in the above two situations are completely different. For the fault caused by misreporting due to the failure of some components in the high-voltage acquisition circuit, its fault level is relatively low, while for the fault that actually occurs due to abnormal load causing the voltage of the battery pack to rise, the level is relatively high. Since the above two faults cannot be distinguished, it is necessary to uniformly execute according to the highest fault level, resulting in the vehicle being unable to start normally at the user end.

[0039] It is not difficult to find that the traditional high-voltage acquisition link has problems of imperfect functions and low reliability.

[0040] Accordingly, this embodiment provides a solution to the above technical problems. The following will describe the detailed solutions of the high-voltage acquisition self-checking circuit, battery management system, and vehicle provided by the embodiments of the present invention in combination with Figure 2 Describe the detailed solutions of the high-voltage acquisition self-checking circuit, battery management system, and vehicle provided by the embodiments of the present invention.

[0041] Figure 2 It is a schematic structural diagram of the high-voltage acquisition self-checking circuit provided by this embodiment.

[0042] As Figure 2 shown, the high-voltage acquisition self-checking circuit provided by the embodiments of the present invention can be applied to the high-voltage acquisition circuit of the battery pack. The circuit specifically includes: a battery pack cut-off sub-circuit 110, a low-voltage source access sub-circuit 120, and a comparison detection sub-circuit 130.

[0043] The battery pack cut-off sub-circuit 110 is respectively connected to the battery pack PACK and the high-voltage acquisition circuit. The low-voltage source access sub-circuit 120 is respectively connected to the low-voltage power supply and the high-voltage acquisition circuit. The comparison detection sub-circuit 130 is connected to the sampling resistor R2 in the high-voltage acquisition circuit.

[0044] In the abnormal state of high-voltage acquisition, the battery pack disconnection sub-circuit 110 disconnects the battery pack PACK from the high-voltage acquisition circuit according to the received first set of control signals; the low-voltage source access sub-circuit 120 accesses the low-voltage power supply to the high-voltage acquisition circuit according to the received second set of control signals; after the comparison detection sub-circuit 130 compares the voltage value of the sampling resistor R2 with the upper voltage limit value and the lower voltage limit value respectively, it outputs a self-check level signal for characterizing the self-check result.

[0045] It can be understood that since the series branch formed by the voltage-dividing resistor R1 and the sampling resistor R2 in the high-voltage acquisition circuit is connected to both ends of the battery pack PACK, in this embodiment, both the battery pack disconnection sub-circuit 110 and the low-voltage source access sub-circuit 120 have a certain connection relationship with the voltage-dividing resistor R1 and the sampling resistor R2, so as to be connected to the high-voltage acquisition circuit.

[0046] In one embodiment, referring to Figure 2 , the battery pack disconnection sub-circuit 110 specifically includes: a first opto-coupler switch Q1, a second opto-coupler switch Q4, and a third opto-coupler switch Q5.

[0047] The first opto-coupler switch Q1 is respectively connected to the positive electrode of the battery pack PACK and the first end of the high-voltage acquisition circuit, the second opto-coupler switch Q4 is respectively connected to the negative electrode of the battery pack PACK and the second end of the high-voltage acquisition circuit, and the third opto-coupler switch Q5 is connected in the high-voltage acquisition circuit.

[0048] As Figure 2 shown, the first opto-coupler switch Q1 is specifically connected to the voltage-dividing resistor R1, the third opto-coupler switch Q5 is connected in series on the series branch of the voltage-dividing resistor R1 and the sampling resistor R2 and is connected to the sampling resistor R2, and the second opto-coupler switch Q4 is connected to the third opto-coupler switch Q5.

[0049] In practical applications, after the main control chip in the battery management system detects the abnormal state of high-voltage acquisition, it will send a first set of control signals to the battery pack disconnection sub-circuit 110. The first set of control signals includes a first sub-signal INPUT1 sent to the first opto-coupler switch Q1, a second sub-signal INPUT3 sent to the second opto-coupler switch Q4, and a third sub-signal INPUT4 sent to the third opto-coupler switch Q5.

[0050] The above three sub-signals are all level signals and have the same level state. For example, the main control chip can send the first sub-signal INPUT1, the second sub-signal INPUT3, and the third sub-signal INPUT4, all of which are in the low-level state, to the three opto-coupler switches to control the three opto-coupler switches to be all disconnected, so as to cut off the connection path between the battery pack PACK and the high-voltage acquisition circuit.

[0051] In one embodiment, referring to Figure 2, the battery pack cut-off sub-circuit 110 may further include: a first current-limiting resistor R3, a second current-limiting resistor R9, and a third current-limiting resistor R10.

[0052] The first current-limiting resistor R3 is connected to the first opto-coupler switch Q1, the second current-limiting resistor R9 is connected to the second opto-coupler switch Q4, and the third current-limiting resistor R10 is connected to the third opto-coupler switch Q5.

[0053] In this embodiment, by correspondingly providing a current-limiting resistor for each opto-coupler switch, each sub-signal can be input into its corresponding opto-coupler switch after passing through the current-limiting resistor, and the circuit works more stably and safely.

[0054] In one embodiment, referring to Figure 2 , the low-voltage source access sub-circuit 120 specifically includes: a first MOS transistor Q2, a second MOS transistor Q6, and a triode Q3.

[0055] The first MOS transistor Q2 is respectively connected to the low-voltage power supply and the high-voltage acquisition circuit, the triode Q3 is respectively connected to the low-voltage power supply and the first MOS transistor Q2, and the second MOS transistor Q6 is respectively connected to the high-voltage acquisition circuit and the ground terminal.

[0056] In this embodiment, the first MOS transistor Q2 is specifically a PMOS transistor, the second MOS transistor Q6 is specifically an NMOS transistor, the triode Q3 is specifically an NPN-type triode, the first MOS transistor Q2 is specifically connected to the voltage-dividing resistor R1 in the high-voltage acquisition circuit, and the second MOS transistor Q6 is specifically connected to the sampling resistor R2 in the high-voltage acquisition circuit.

[0057] In practical applications, after the main control chip in the battery management system detects an abnormal high-voltage acquisition state, it will send a second set of control signals to the low-voltage source access sub-circuit 120. The second set of control signals specifically includes a fourth sub-signal INPUT2 sent to the triode Q3 and a fifth sub-signal INPUT5 sent to the second MOS transistor Q6.

[0058] Both the above-mentioned fourth sub-signal INPUT2 and fifth sub-signal INPUT5 are level signals, and the level states are opposite. For example, after the main control chip detects an abnormal high-voltage acquisition state, it can send a fourth sub-signal INPUT2 in a low-level state to control the triode Q3 to turn off, and at the same time, the first MOS transistor Q2 is turned on, and a fifth sub-signal INPUT5 in a high-level state is sent to control the second MOS transistor Q6 to turn on. In this way, the current will sequentially pass through the low-voltage power supply, the voltage-dividing resistor R1, the sampling resistor R2, the second MOS transistor Q6 to the ground terminal, thereby connecting the low-voltage power supply to the high-voltage acquisition circuit. In practical applications, the low-voltage power supply can use a 12V DC power supply.

[0059] In one embodiment, referring to Figure 2, the low-voltage source access sub-circuit 120 may further include: a fourth current-limiting resistor R4;

[0060] The fourth current-limiting resistor R4 is respectively connected to the low-voltage power supply and the collector of the triode Q3.

[0061] In this embodiment, the fourth current-limiting resistor R4 is in series with the triode Q3, and one end of the series branch formed by the two is connected to the low-voltage power supply, and the other end is connected to the first MOS transistor Q2.

[0062] In one embodiment, the comparison and detection sub-circuit 130 specifically includes: a comparison module and a flip-flop U3.

[0063] The comparison module is respectively connected to the sampling resistor R2 and the flip-flop U3.

[0064] The comparison module is configured to compare the voltage value of the sampling resistor R2 with the upper voltage limit value and then output a first result signal to the flip-flop U3. The comparison module is further configured to compare the voltage value of the sampling resistor R2 with the lower voltage limit value and then output a second result signal to the flip-flop U3.

[0065] After receiving the first result signal and the second result signal, the flip-flop U3 outputs a self-check level signal for characterizing the self-check result according to the level states of the first result signal and the second result signal.

[0066] It can be understood that both the first result signal and the second result signal output by the comparison module are level signals, and the level states of the two level signals are specifically determined according to the comparison result of the comparison link, and can be the same or different.

[0067] The flip-flop U3 is mainly configured to output a self-check level signal according to the level states of the first result signal and the second result signal respectively according to a preset operation logic. In this embodiment, the self-check level signal includes two parts: a first output sub-signal OUTPUT1 and a second output sub-signal OUTPUT2. According to the level states of the first output sub-signal OUTPUT1 and the second output sub-signal OUTPUT2, the self-check result can be directly determined.

[0068] In one embodiment, referring to Figure 2 , the comparison module specifically includes a first comparator U1 and a second comparator U2.

[0069] The inverting input terminal of the first comparator U1 and the non-inverting input terminal of the second comparator U2 are both connected to the sampling resistor R2. The non-inverting input terminal of the first comparator U1 is connected to the upper voltage limit value, and the inverting input terminal of the second comparator U2 is connected to the lower voltage limit value. The output terminals of the first comparator U1 and the second comparator U2 are both connected to the flip-flop U3.

[0070] In this embodiment, the first comparator U1 is mainly used to compare the voltage value of the sampling resistor R2 with the upper voltage limit value, and the second comparator U2 is mainly used to compare the voltage value of the sampling resistor R2 with the lower voltage limit value. Both the first comparator U1 and the second comparator U2 satisfy:

[0071] When the input voltage at the non-inverting input terminal is greater than the input voltage at the inverting input terminal, a result signal in a high-level state is output. Conversely, when the input voltage at the non-inverting input terminal is less than the input voltage at the inverting input terminal, a result signal in a low-level state is output.

[0072] In one embodiment, referring to Figure 2 , the comparison module may further include: a first voltage-dividing resistor R5, a second voltage-dividing resistor R6, a third voltage-dividing resistor R7, and a fourth voltage-dividing resistor R8.

[0073] The first end of the first voltage-dividing resistor R5 and the first end of the second voltage-dividing resistor R6 are both connected to the non-inverting input terminal of the first comparator U1. The second end of the first voltage-dividing resistor R5 is connected to the low-voltage power supply, and the second end of the second voltage-dividing resistor R6 is grounded.

[0074] The first end of the third voltage-dividing resistor R7 and the first end of the fourth voltage-dividing resistor R8 are both connected to the inverting input terminal of the second comparator U2. The second end of the third voltage-dividing resistor R7 is connected to the low-voltage power supply, and the second end of the fourth voltage-dividing resistor R8 is grounded.

[0075] In this embodiment, the resistance values of the four voltage-dividing resistors can be specifically set according to the values of the upper voltage limit value and the lower voltage limit value.

[0076] Next, in combination with Figure 2 the working principle of the high-voltage acquisition self-checking circuit provided in this embodiment will be described:

[0077] When the high-voltage acquisition state is normal, the main control chip outputs a first sub-signal INPUT1, a second sub-signal INPUT3, a third sub-signal INPUT4, and a fourth sub-signal INPUT2 in a high-level state. The first opto-coupler switch Q1, the second opto-coupler switch Q4, and the third opto-coupler switch Q5 are normally closed, and the triode Q3 is turned on. At this time, the low-voltage power supply is not connected to the circuit, and the high-voltage acquisition circuit can work normally.

[0078] When a high-voltage acquisition abnormal state occurs, the main control chip outputs a first sub-signal INPUT1, a second sub-signal INPUT3, and a third sub-signal INPUT4 in a low-level state. The first opto-coupler switch Q1, the second opto-coupler switch Q4, and the third opto-coupler switch Q5 are all turned off, which is equivalent to disconnecting the high-voltage circuit where the battery pack is located from the high-voltage acquisition circuit.

[0079] Meanwhile, the main control chip sends the fourth sub-signal INPUT2 in the low-level state to the triode Q3, and the triode Q3 is turned off. Since the first MOS transistor Q2 is a PMOS transistor, when the gate-source voltage is less than a certain value, the first MOS transistor Q2 is closed, thereby introducing the 12V low-voltage power supply into the high-voltage acquisition circuit. At the same time, the main control chip sends the fifth sub-signal INPUT5 in the high-level state to the second MOS transistor Q6. Since the second MOS transistor Q6 is an NMOS transistor, when the gate-source voltage is greater than a certain value, the second MOS transistor Q6 is closed, thereby grounding the negative pole of the 12V low-voltage power supply.

[0080] At this time, the high-voltage acquisition circuit consists of a low-voltage power supply, a voltage-dividing resistor R1, and a sampling resistor R2. Then, the input voltages obtained at the inverting input terminal of the first comparator U1 and the non-inverting input terminal of the second comparator U2 are both: U 低压电源 ×[R2 / (R1 + R2)]. Assuming that the accuracies of both the voltage-dividing resistor R1 and the sampling resistor R2 are 1%, then when the resistance value of the sampling resistor R2 is the largest and the resistance value of the voltage-dividing resistor R1 is the smallest, the voltage division value of the sampling resistor R2 is the largest; conversely, when the resistance value of the sampling resistor R2 is the smallest and the resistance value of the voltage-dividing resistor R1 is the largest, the voltage division value of the sampling resistor R2 is the smallest.

[0081] Therefore, the upper limit value of the voltage of the sampling resistor R2 is specifically:

[0082] Umax = U 低压电源 ×[(1.01×R2) / (0.99×R1 + 1.01×R2)] (1)

[0083] The upper limit value of the voltage of the sampling resistor R2 is specifically:

[0084] Umin = U 低压电源 ×[(0.99×R2) / (1.01×R1 + 0.99×R2)] (2)

[0085] Assuming that the resistance value of the voltage-dividing resistor R1 is 6000KΩ and the resistance value of the sampling resistor R2 is 43KΩ, then the upper limit value of the voltage Umax = 0.0874V and the lower limit value of the voltage Umin = 0.0837V can be calculated.

[0086] According to the upper limit value and the lower limit value of the voltage, the voltage division ratios of the first voltage-dividing resistor R5, the second voltage-dividing resistor R6, the third voltage-dividing resistor R7, and the fourth voltage-dividing resistor R8 can be obtained. Furthermore, the resistance values of the four voltage-dividing resistors can be determined. Still taking the above example, the resistance values of the four voltage-dividing resistors are respectively R5 = R7 = 10000KΩ, R6 = 874Ω, and R8 = 837Ω.

[0087] Since the main failure mode of the resistor is open circuit, when considering the abnormal situation where the sampling resistor or the voltage-dividing resistor is open-circuited or the impedance increases, the working process of the high-voltage acquisition self-checking circuit is as follows:

[0088] When the voltage-dividing resistor R1 increases, the voltage division of the sampling resistor R2 becomes smaller and will be less than the upper voltage limit value and the lower voltage limit value. Then, the input voltages of the non-inverting input terminals of the first comparator U1 and the second comparator U2 are both less than the input voltages of the inverting input terminals. Both the first comparator U1 and the second comparator U2 output result signals in a low-level state, that is, both the first result signal and the second result signal are low-level signals.

[0089] When the voltage-dividing resistor R2 decreases, the voltage division of the sampling resistor R2 becomes larger and will be greater than the upper voltage limit value and the lower voltage limit value. Then, the input voltages of the non-inverting input terminals of the first comparator U1 and the second comparator U2 are both greater than the input voltages of the inverting input terminals. Both the first comparator U1 and the second comparator U2 output result signals in a high-level state, that is, both the first result signal and the second result signal are high-level signals.

[0090] If both the voltage-dividing resistor R1 and the sampling resistor R2 are normal, the voltage division value of the sampling resistor R2 is between the upper voltage limit value and the lower voltage limit value. Then, the input voltage of the non-inverting input terminal of the first comparator U1 is less than the input voltage of the inverting input terminal, and the first comparator U1 outputs a first result signal in a low-level state. While the input voltage of the non-inverting input terminal of the second comparator U2 is greater than the input voltage of the inverting input terminal, and the second comparator U2 outputs a second result signal in a high-level state. Therefore, the following result correspondence table can be obtained:

[0091] Table 1 Comparison Table of the Signal Level States of the Comparator Output Results

[0092]

[0093] The flip-flop U3 is connected to the control terminal. When the signal level states of the result signals output by the two comparators are the same, it can be determined that the high-voltage acquisition loop fails. The first output sub-signal OUTPUT1 is a high-level signal, and when both the first result signal and the second result signal are high-level signals, the second output sub-signal OUTPUT2 is a high-level signal.

[0094] When the signal level states of the result signals output by the two comparators are different, both the first output sub-signal OUTPUT1 and the second output sub-signal OUTPUT2 output by the flip-flop U3 are low-level signals. Therefore, the following result correspondence table can be obtained:

[0095] Table 2 Comparison Table of the Signal Level States of the Self-Checking Level Signals Output by the Flip-Flop

[0096]

[0097]

[0098] According to Table 2 above, when the first output sub-signal OUTPUT1 output by the trigger U3 is in a high-level state, it can be determined that a false alarm fault is caused by the failure of the high-voltage acquisition circuit. At this time, the low-level fault mode can be entered for processing.

[0099] When the first output sub-signal OUTPUT1 output by the trigger U3 is in a low-level state, it can be determined that a real fault has occurred. At this time, the high-level fault mode can be entered for processing.

[0100] In addition, according to the level state of the second output sub-signal OUTPUT2 output by the trigger U3, the failure position of the high-voltage acquisition circuit can be further determined. Specifically, if the second output sub-signal OUTPUT2 is in a low-level state, it can be determined that the voltage-dividing resistor has failed; if the second output sub-signal OUTPUT2 is in a high-level state, it can be determined that the sampling resistor has failed.

[0101] It can be seen that the high-voltage acquisition self-checking circuit provided in this embodiment can, after an abnormal high-voltage acquisition state occurs, timely cut off the connection between the battery pack and the high-voltage acquisition circuit through the battery pack cut-off sub-circuit to ensure the safe operation of the circuit. At the same time, it can also introduce a low-voltage power supply into the high-voltage acquisition circuit through the low-voltage source access sub-circuit, and detect the fault position through the comparison and detection sub-circuit, making the function of the high-voltage acquisition link more perfect, and further improving the reliability of the high-voltage monitoring link.

[0102] In addition, the present invention also provides a battery management system, including the high-voltage acquisition self-checking circuit provided in each of the above embodiments.

[0103] Furthermore, the present invention also provides a vehicle, including the high-voltage acquisition self-checking circuit provided in each of the above embodiments or the above battery management system.

[0104] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of each embodiment of the present invention.

Claims

1. A high voltage acquisition self-test circuit, characterized in that: A high voltage acquisition circuit applied to a battery pack, the circuit comprising: a battery pack cut-off subcircuit, a low voltage source access subcircuit and a comparison detection subcircuit; The battery pack cut-off subcircuit is connected to the battery pack and the high-voltage acquisition circuit respectively, the low-voltage source access subcircuit is connected to the low-voltage power supply and the high-voltage acquisition circuit respectively, and the comparison detection subcircuit is connected to the sampling resistor in the high-voltage acquisition circuit; In the abnormal state of high-voltage acquisition, the battery pack cut-off subcircuit disconnects the battery pack from the high-voltage acquisition circuit according to the first group of control signals received; the low-voltage source connection subcircuit connects the low-voltage power supply to the high-voltage acquisition circuit according to the second group of control signals received; the comparison detection subcircuit compares the voltage value of the sampling resistor with the voltage upper limit value and the voltage lower limit value respectively, and outputs a self-test level signal used to characterize the self-test result.

2. The high voltage acquisition self-test circuit according to claim 1, characterized in that: The battery pack cut-off subcircuit includes: a first optocoupler switch, a second optocoupler switch and a third optocoupler switch; The first optocoupler switch is respectively connected to the positive electrode of the battery pack and the first end of the high-voltage collection loop, the second optocoupler switch is respectively connected to the negative electrode of the battery pack and the second end of the high-voltage collection loop, and the third optocoupler switch is connected to the high-voltage collection loop.

3. The high voltage acquisition self-test circuit according to claim 2, characterized in that: The battery pack cut-off subcircuit further includes: a first current limiting resistor, a second current limiting resistor and a third current limiting resistor; The first current limiting resistor is connected to the first optocoupler switch, the second current limiting resistor is connected to the second optocoupler switch, and the third current limiting resistor is connected to the third optocoupler switch.

4. The high voltage acquisition self-test circuit according to claim 1, characterized in that: The low voltage source access sub-circuit comprises: a first MOS tube, a second MOS tube and a triode; The first MOS tube is connected to the low voltage power supply and the high voltage collection loop respectively, the triode is connected to the low voltage power supply and the first MOS tube respectively, and the second MOS tube is connected to the high voltage collection loop and the ground end respectively.

5. The high voltage acquisition self-test circuit according to claim 4, characterized in that: The low voltage source access sub-circuit further includes: a fourth current limiting resistor; The fourth current limiting resistor is connected to the low-voltage power supply and the collector of the transistor respectively.

6. The high voltage acquisition self-test circuit according to claim 1, characterized in that: The comparison detection subcircuit comprises: a comparison module and a trigger; The comparison module is connected to the sampling resistor and the trigger respectively; The comparison module is used to compare the voltage value of the sampling resistor with the voltage upper limit value, and then output a first result signal to the trigger; the comparison module is also used to compare the voltage value of the sampling resistor with the voltage lower limit value, and then output a second result signal to the trigger; After receiving the first result signal and the second result signal, the trigger outputs a self-test level signal for representing the self-test result according to the level state of the first result signal and the level state of the second result signal.

7. The high voltage acquisition self-test circuit according to claim 6, characterized in that: The comparison module includes: a first comparator and a second comparator; The inverting input terminal of the first comparator and the non-inverting input terminal of the second comparator are both connected to the sampling resistor, the non-inverting input terminal of the first comparator is connected to the voltage upper limit value, the inverting input terminal of the second comparator is connected to the voltage lower limit value, and the output terminal of the first comparator and the output terminal of the second comparator are both connected to the trigger.

8. The high voltage acquisition self-test circuit according to claim 7, characterized in that: The comparison module further includes: a first voltage-dividing resistor, a second voltage-dividing resistor, a third voltage-dividing resistor and a fourth voltage-dividing resistor; The first end of the first voltage-dividing resistor and the first end of the second voltage-dividing resistor are both connected to the non-inverting input terminal of the first comparator, the second end of the first voltage-dividing resistor is connected to the low-voltage power supply, and the second end of the second voltage-dividing resistor is grounded; The first end of the third voltage-dividing resistor and the first end of the fourth voltage-dividing resistor are both connected to the inverting input terminal of the second comparator, the second end of the third voltage-dividing resistor is connected to the low-voltage power supply, and the second end of the fourth voltage-dividing resistor is grounded.

9. A battery management system, characterized in that: It comprises the high voltage acquisition self-test circuit as claimed in any one of claims 1 to 8.

10. A vehicle, characterized in that: It comprises the high voltage acquisition self-test circuit as described in any one of claims 1 to 8 or the battery management system as described in claim 9.

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